tag:blogger.com,1999:blog-369137682024-03-19T01:47:06.153-07:00Unreasonable RocketReasonable people adapt themselves to the world.
Unreasonable people attempt to adapt the world to themselves.
All progress, therefore, depends on unreasonable people.
- George Bernard Shaw.Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.comBlogger427125tag:blogger.com,1999:blog-36913768.post-33894394309238397492022-10-03T12:03:00.002-07:002022-10-03T12:03:30.237-07:00Solar Plane continued...<p> A solar plane with multiple rows on the wings will have differnt illumination on each row and on each wing. The last plane had 3 rows x 2 wings. So 6 total channels of power point tracking.<br /><br />I think the new design is going to be slightly smaller with two rows. The 12 or 13 cells in series will have a max output voltage of ~7.5V. So my system battery/bus voltage will need to be above that.<br />I'm thinking 6S LiIon.<br /><br />So I wanted to simulate the power circuitry of the solar mppt system.<br />I used the LTC Spice and built a singe solar cell model:<br /><br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEh7RdpFT5m9ySSnfyiQWYh5fd-_aUWmMHp8g_soeAZEv7EWyEDTAb-ZjTvwj66tJuo5rRNH6iMQu8uwnUWiG6rhFlnpP6g9P4eQ5klMuR2r6LLSFtGcUMdrfs4qcUurpMBN9jWPbk4JgTYPedfsR07VZM3V61QcuN9gyr14q18d_lLrCrrLU6M" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="325" data-original-width="1343" height="77" src="https://blogger.googleusercontent.com/img/a/AVvXsEh7RdpFT5m9ySSnfyiQWYh5fd-_aUWmMHp8g_soeAZEv7EWyEDTAb-ZjTvwj66tJuo5rRNH6iMQu8uwnUWiG6rhFlnpP6g9P4eQ5klMuR2r6LLSFtGcUMdrfs4qcUurpMBN9jWPbk4JgTYPedfsR07VZM3V61QcuN9gyr14q18d_lLrCrrLU6M" width="320" /></a></div><br />I then combined 10 of these to be a 10 cell array....<br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEj7p6r1ajelUQ4x-nl1VZxYx4FowgW_pX5yLyQ-wVx5hm6ZBE6Xd5Mlg69XyxjWtnAOynEWmNdIfZ2gP1hpTA4QCSwE6qEX6mWQwMm41zvDxNI2S2lTWMxrTjoA33RNrf7ZVxYPWBNl3ZuCULrny8CP0eALeXdQlGJUAHvm4BK5Va9JfyOvKhE" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="807" data-original-width="2040" height="127" src="https://blogger.googleusercontent.com/img/a/AVvXsEj7p6r1ajelUQ4x-nl1VZxYx4FowgW_pX5yLyQ-wVx5hm6ZBE6Xd5Mlg69XyxjWtnAOynEWmNdIfZ2gP1hpTA4QCSwE6qEX6mWQwMm41zvDxNI2S2lTWMxrTjoA33RNrf7ZVxYPWBNl3ZuCULrny8CP0eALeXdQlGJUAHvm4BK5Va9JfyOvKhE" width="320" /></a><br /><br /></div>Then I used the LTC7804 test jig as the basis for a full up simulation.<br /><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEiVJRGPsmTBXAEj5pTCUc53eb941Ktp57dfxbK1CMqDXOQIbcd8_xjuil_G1qKmumOX8FfyDPxhUuEoMBaFJg7dljXUR3Uhm9RWoMO0Zbd7Z7J_0qwsurlluxCdvg6h4FPH0zPgr2aVc6kAa6zGdWydvsrMLtLqXsF2cVNydK2YZrAMz6z8e2M" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="1485" data-original-width="3257" height="146" src="https://blogger.googleusercontent.com/img/a/AVvXsEiVJRGPsmTBXAEj5pTCUc53eb941Ktp57dfxbK1CMqDXOQIbcd8_xjuil_G1qKmumOX8FfyDPxhUuEoMBaFJg7dljXUR3Uhm9RWoMO0Zbd7Z7J_0qwsurlluxCdvg6h4FPH0zPgr2aVc6kAa6zGdWydvsrMLtLqXsF2cVNydK2YZrAMz6z8e2M" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div>So instead of regulating the output voltage it now regulates the input voltage.<br />The op amp on the left side inverts, amplifies and offsets the cell array voltage and adapts it to the LTC7804 1.2V reference.<br /><br />The two voltage sources on the left side Vtargmppt and Voffset will be combined into a low power precision DAC from whatever microcontroller I choose to drive this mess. (One could thevenize the resistance and voltages to form a single source, but since no significant current should flow into the<br />+ node of the op amp the resistance probably does not really matter.<br />Basic power path is decided, now to make a couple more decisions and prototype in the real world with a set of real cells.<br /><br />For deciding the MPPT tracking point there are several choices:<br />Random path search.<br />Percentage of Voc (what I chose last time)<br />Table of V vs Cell temp.<br /><br />I'll play with all three modes... I'm hoping the cell temp vs V works well.<br />The data sheet says Vmppt is 5.8V at 25C and is -1.84 mv/deg C.<br /><br />On the airframe front I've also been playing with basic aircraft layout using<br />XFLR5 to design the airframe. While a solar wing really wants to be rectangular the<br />improvement in minimum sink with an additional tapered panel is so large that its probably worth doing even if it has no solar cells. (Winglets have same effect, but shadow top side cells so that does not work.) <br /><br />I really need to get a good target weight I'm comfortable with so I can have a target design and then determine gram/watt sort of sensitivities to make proper power/weight trades.<br />an example trade would be to add cells to the tailboom. Hard to balance as all the weight is aft and <br />so will likely need added wt forward. The weight and drag acts 24 hrs a day. Added power is only useful for 12hrs and then requires added battery wt to use the excess power overnight.<br /><br />Adding panels in the taper tips are at differnt angle/solar incidence than the main wing cells.<br />So they need their own mppt tracker. does it make sense to add a tracker for 15W of cell<br />running at 1.5 to 2 V so efficiency will be poor. With the LTC7408 it has synchronous reftification so that should help at low voltages. (Inductor will be smaller as well).<br /><br />Speaking of inductors I've gotten proper aluminum magnet wire quoted at $2.20/ft and 1Kft minimum order. So I've 3d printed some air core toroid forms and wound un insulated aluminum craft wire on these...made some light inductors.... <br /><br />Trades/Trades/optimizations as far as the eye can see... More later.<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><p></p>Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com29tag:blogger.com,1999:blog-36913768.post-31188409082599557692022-09-17T11:11:00.000-07:002022-09-17T11:11:58.360-07:00Solar powered planes.<p><br /> In 2004 I built a solar powered RC plane.<br />You can see pictures and read about it sees some pictures and relive its sad end here: <a href="http://www.rasdoc.com/splinter/solar2004.htm">Old web page from 2004</a><br /><br />I'm going to try this project again.</p><p>In the 18 years since this flew a number of things have improved:</p><p></p><ul style="text-align: left;"><li>Microscopic autopilots for RC planes are COTS. (mRo <5gm etc) I no longer have to build my own.</li><li>Long range RC control and telemetry links are COTS (Crossfire, ELRS, Dragonlink)<br />I no longer have to build my own.</li><li>The solar cells have improved. The new SunPower C60 cells are 6.5 gm 3.5W 22% efficient and Flexible. The A-300 cells I used 18 yrs ago were:12 gm, 3W 20% efficient, and pretty rigid.</li></ul><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQZm2TpmhoypA3pWF6HX6JJXMtkiOLlKlItydUU8ObhTr4NYWbNmbGy-vO3_jUgh74N12bYQDsTaiJTrL-8xqsIznrM4og3ywSS7lHwGXkKH3iUeksv2vPW2wXV6SAzWKZK5JmzR6-w0r0vYOLtSaP915bIjOhS1nXMQnAvwElEWn3VNA8KIA/s4080/PXL_20220917_164830453.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="3072" data-original-width="4080" height="241" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiQZm2TpmhoypA3pWF6HX6JJXMtkiOLlKlItydUU8ObhTr4NYWbNmbGy-vO3_jUgh74N12bYQDsTaiJTrL-8xqsIznrM4og3ywSS7lHwGXkKH3iUeksv2vPW2wXV6SAzWKZK5JmzR6-w0r0vYOLtSaP915bIjOhS1nXMQnAvwElEWn3VNA8KIA/s320/PXL_20220917_164830453.jpg" width="320" /></a><br />Old cell left, new cell right</div><br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgb3msBo8PYAOj9W8TPX5WTxiZp-i1yo3wzk4_SWF13bXCo8z6Hc2BeVTvLCwsP9gR24C4PE5cut2cgUS8KbPJH47pwcV-hgxTKRWfmqXlu-kURjF7EV_paCLl4q4NuL8zUTExZjFxDzCe6YVv9yxSLWl4FAW5cEVftz7P3bnwCHDX6m0y6dFo/s4080/PXL_20220917_164846185.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="4080" data-original-width="3072" height="320" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgb3msBo8PYAOj9W8TPX5WTxiZp-i1yo3wzk4_SWF13bXCo8z6Hc2BeVTvLCwsP9gR24C4PE5cut2cgUS8KbPJH47pwcV-hgxTKRWfmqXlu-kURjF7EV_paCLl4q4NuL8zUTExZjFxDzCe6YVv9yxSLWl4FAW5cEVftz7P3bnwCHDX6m0y6dFo/s320/PXL_20220917_164846185.jpg" width="241" /></a></div><div class="separator" style="clear: both; text-align: center;">The new cells are pretty flexible.</div><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><div>On the old plane I had 3 rows of solar cells on each wing. Each row was wired in series to make about 6.5 volts. I then built a 6 channel MPPT (see: <a href="https://en.wikipedia.org/wiki/Maximum_power_point_tracking">wiki MPPT</a>)<br /><br />The schematic for one channel of my MPPT:<br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEjFxaD9-sNJXiAsjeGL-icFEjFFh5zy-pJWwsgjF9REG7cTkz6lyB2vhoOS61mXrdRvhNHuVwCOC0wqKD3Hynumt4MZUTaxqsBzYeDJkke4nAp5-ftvGjpSnJ0rz4o5QlJcakzIPcN8QUC_00QSJOqgVZ72lmGy-lrLOkzqkzQ-4KauEMUDtHg" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="1273" data-original-width="2177" height="187" src="https://blogger.googleusercontent.com/img/a/AVvXsEjFxaD9-sNJXiAsjeGL-icFEjFFh5zy-pJWwsgjF9REG7cTkz6lyB2vhoOS61mXrdRvhNHuVwCOC0wqKD3Hynumt4MZUTaxqsBzYeDJkke4nAp5-ftvGjpSnJ0rz4o5QlJcakzIPcN8QUC_00QSJOqgVZ72lmGy-lrLOkzqkzQ-4KauEMUDtHg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div>The full 6 channel unit:<br /><br /><br /></div><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSGbaemMcgQ-Nyr_US-I-vdako72otgCyYx-ikMOFnsefecR7tfL7GGjNzVZN0ttWE1g6cfBW5RrwqecgyWkCJzF97Gu-K74DQMfqp-xMVkQh59zt_nc56DJvWWRtoCSP9Kk1UCvLH7dsX2JiTosXXuX_10QEF5DlbLoRzDIxzQcb3y-LOgzc/s3072/MPPT6Ch.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="2048" data-original-width="3072" height="213" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjSGbaemMcgQ-Nyr_US-I-vdako72otgCyYx-ikMOFnsefecR7tfL7GGjNzVZN0ttWE1g6cfBW5RrwqecgyWkCJzF97Gu-K74DQMfqp-xMVkQh59zt_nc56DJvWWRtoCSP9Kk1UCvLH7dsX2JiTosXXuX_10QEF5DlbLoRzDIxzQcb3y-LOgzc/s320/MPPT6Ch.jpg" width="320" /></a><br /><br /><br /></div><br /><p></p><p>This MPPT is setup as a boost converter so the system bus or battery voltage must be above the voltage of the solar string. It also allows solar strings of varying size to feed a common bus. IE I can have a 4 cell panel on the tail, a 4 cell panel on the wing tips and a 2x 10 cell panels on each main wing.<br /><br />There are lots and lots of interesting tradeoffs in this space.<br />At minimum power the wing drag is primarily induced drag. One reduces induced drag by making the wing have a very high aspect ratio and an elliptical lift distribution.<br /><br />If you want the absolute minimum power you want a really high lift airfoil like:<br />S1210:<br /></p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgAVBTGNhEZeku0AaxrJFoiNFq61hWwi9W9WT13h80GBkTWtHAsL33RvG25REc4BnXMcxjMd3jgvWGtEvbubOCA6V07egrBXWIOV0-CocHkr_8bgUMJrpoyXknDGZAktMXh2jbfTfnCqFf54n5eZw5oRqBTuRqonlemm3cmmXs2j5uCKXfEiVk" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="499" data-original-width="2417" height="66" src="https://blogger.googleusercontent.com/img/a/AVvXsEgAVBTGNhEZeku0AaxrJFoiNFq61hWwi9W9WT13h80GBkTWtHAsL33RvG25REc4BnXMcxjMd3jgvWGtEvbubOCA6V07egrBXWIOV0-CocHkr_8bgUMJrpoyXknDGZAktMXh2jbfTfnCqFf54n5eZw5oRqBTuRqonlemm3cmmXs2j5uCKXfEiVk" width="320" /></a><br />Selig S1210</div><br />Yet look how thin the trailing edge is and how hard that would be to build lightly.<br />Heavily under cambered airfoils also have really high pitching moments.<br />(Meaning the airfoil wants to pitch forward and this must be resisted.)<br />Put this airfoil on a really long high aspect ratio wing and its not unheard of for the wing tip to fail in a downward direction... (The airfoil tip tries to twist forward twisting the wing, enough that the wing tip on light structure is now lifting down and bad things ensue.)<br /><br />One could choose an airfoil designed for flying wings (now or very low pitching moment) like <br />MH60:<br /><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/a/AVvXsEgHimtjdgYAKnlrR2cYscfzNCib-UIqks5N-HIwx3pMjmsqOj-Hq2ixBNawu3Wb3KqpmLOkH9LMEW1lnBlcJA8fXiH4Iv8JqPafh7opkFPZGvd7zZNyE4KDtvhYSRryrS7iprrGtlHU09gUgnS9KLVZKZj34_wQaIt6BJfD7FR9nOAiXXLJzSs" style="margin-left: 1em; margin-right: 1em;"><img alt="" data-original-height="393" data-original-width="2337" height="54" src="https://blogger.googleusercontent.com/img/a/AVvXsEgHimtjdgYAKnlrR2cYscfzNCib-UIqks5N-HIwx3pMjmsqOj-Hq2ixBNawu3Wb3KqpmLOkH9LMEW1lnBlcJA8fXiH4Iv8JqPafh7opkFPZGvd7zZNyE4KDtvhYSRryrS7iprrGtlHU09gUgnS9KLVZKZj34_wQaIt6BJfD7FR9nOAiXXLJzSs" width="320" /></a></div><br />Much easier to build a very light structure with this trailing edge and the torsional rigidity of the wing will matter a lot less.<br /><br /><br />The minimum power airfoil (assuming an infinite wing) is where Cl^3/2/Cd is maximum.<br />For the 1210 : 109 For the MH60 its : 68....<br /><br />So the minimum sink is roughly proportional to weight ^ 1/2 Min power is thus weight ^(3/2)<br />So for a 1000gm airplane you could add a couple hundred extra grams and be even.<br /><br />So if one wanted to fly over night.... using the potential energy of the aircraft as a battery sink rate is only effected by wt ^1/2 where if you wanted to fly all night at constant altitude via battery then assuming the battery is 30 to 50% of the mass (reasonable assumption) then each extra gram of structure is bad by an additional requirement for more battery.<br /><br />Like I said a really complex trade space...<br /><br /><br />Looking at the professional Aerospace for hints/clues is not really helpful...<br />Helios was a flying wing, that failed due to complex aerodynamic, structural, and turbulence interactions. See Report <a href="https://www.nasa.gov/centers/dryden/news/ResearchUpdate/Helios/Previews/index.html">here</a><br /><br />The Solar impulse and <a href="https://en.wikipedia.org/wiki/Airbus_Zephyr">Airbus Zypher</a> both chose a more traditional aircraft platform.<p></p><p><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /></p><div class="separator" style="clear: both; text-align: center;"><br /></div><br /><br /><br /><br /><br /><br /><br /><p></p><p><br /><br /></p>Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com9tag:blogger.com,1999:blog-36913768.post-87838448383506851692019-02-22T15:03:00.000-08:002019-02-22T15:10:45.566-08:00Creating new things in the real world, Musk, Tesla Spacex etc....I'm a space geek, much of my social interaction is with other space geeks.<br />
A lot of these people worship what Spacex and Elon have accomplished.<br />
<br />
At the same time I've been more and more convinced that Tesla is going to fail.<br />
This causes some significant personal cognitive dissonance.<br />
<br />
The following is my attempt to work this out ...<br />
<br />
Making a new thing is hard. You will fail, over and over again, you will fail.<br />
Edison tried thousands of light bulb filaments before he found one that worked.<br />
<br />
One of the really cool things about spacex is that they let you see them fail.<br />
The blooper reel of landing attempts is outstanding.<br />
Attempting to do something new and hard will have failures.<br />
Trying something new in engineering or in business will have failures.<br />
<br />
Because of Spacex:<br />
<ul>
<li>We now know that first stage reuse can make sense.</li>
<li>We now know that the iterate fast model of engineering works for at least some of the aerospace world.</li>
<li>Supersonic retro propulsion works.</li>
<li>You can (given the right engineering team ) built rockets for a tiny fraction of what the big aerospace primes charge.</li>
</ul>
All of this is new information in the world due to Spacex efforts.<br />
Everything above this line is engineering....<br />
<br />
We still don't really know that the Spacex way will work in a business sense.<br />
Recent layoffs and recent failed funding raise make this more questionable than it was 12 months ago. (Its clear that the business case for the large aerospace primes, does not work absent billions in direct government subsidies)<br />
<br />
From an engineering stand point Spacex has been somewhat innovative....<br />
SpaceX have either surpassed or are approaching 50% of the total world wide launches.<br />
In my opinion (if ancillary things like tesla don't take it out) Spacex will survive long term and the world will be a better place because of that. (see my earlier <a href="https://unreasonablerocket.blogspot.com/2009/08/why-space-matters.html">dialog on why space matters</a>).<br />
<br />
The space business has been run for a long time by cost plus contractors working for governments.<br />
This is not a place where innovation thrives.<br />
<br />
The Car business on the other had has been a brutally competitive market with microscopic margins fought over by efficient international behemoths. Its a hard brutal world.<br />
<br />
Tesla managed to crack open that market and with the S and X, they delivered a well received high end quality product that changed the perception of the world. Now every one of those behemoths is planning an EV. Just having a shot at this is a huge achievement...<br />
<br />
Some how the engineer Elon that allows us to see spacex failures, has been unable to admit to the world that their are also business failures. By any unbiased measure Solar City was weeks from failing when Tesla bought it. This burdens Tesla with a millstone that makes the difficult task of breaking into the brutally competitive car market even harder.<br />
<br />
Watching the Engineer Elon do magic things at spacex I greatly admire what he/they have accomplished. Watching the Business Man Elon commit what looks very much like Fraud to save a failing business I do not admire. Business ethics matter and used to matter to Elon (see his several year old tweet about debts and personal responsibility for Solar City Debits) <br />
<br />
Some how the pressure to not have the business fail has pushed pushed Elon to do things that cross the ethical line in a way that has caused me to loose my respect for Business Man Elon...<br />
<br />
The Big ones : <br />
<ul>
<li>Solar City Purchase and fraudulent Solar roof presentation.</li>
<li>Model 3 production guarantees on the eve of big Tesla Bond Raise.</li>
<li>Screwing over his devoted customer base with the crappy quality M3 and things like not refunding deposits.</li>
<li>The $420 Funding secured Tweet and subsequent response.</li>
<li>The flipping the Bird at the SEC taunting tweets.</li>
<li>The recent guidance on Tesla that just does not pass the smell test.</li>
<li>The Fraudulent Guarantees in the Buffalo Solar city Factory morass.</li>
<li>Treatment of personnel (At both Spacex and Tesla) You can only run in start up panic mode for so long before it destroys people. I have many space friends that have left Spacex because of the relentless pressure.</li>
</ul>
<div>
It is my opinion that Tesla is very close to failing and will fail in the next 24 months.</div>
<div>
It is my hope that this does not destroy Spacex. Elon has generated significant personal liabilities in his Tesla dealings, and if Tesla fails the only real Asset Elons owns is spacex. Spacex will be a very different and less dynamic place when its owned by plaintive s lawyers rather than Elon.<br />
<br />
I find the whole affair sad. I wish Elon had stuck to Spacex and just focused there.<br />
<br />
I know that some of my followers that see the Spacex brilliance and subscribe toe the "Saint Elon can do anything" view will rush in to defend Tesla.<br />
I don't want to rehash that argument here. lets us just agree to disagree and we will know who is correct in 18 months or so.</div>
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com331tag:blogger.com,1999:blog-36913768.post-20322736500880205112018-12-22T17:14:00.003-08:002018-12-22T17:14:50.479-08:00Low Low Low cost liquid thrust chambers...<br />
<div class="MsoNormal">
The very premise of what I’m trying to do is low cost as a
primary design goal.<br />
One has to question ALL of ones assumptions… <br />
I personally fired the first ever 3D printed Regenerativly cooled liquid rocket
engine.<br />
ever fired in the world (2009) <br />
I’ve done a lot of work in that space. The 3D aluminum costs are coming down….<br />
Its cool high tech and in many ways awesome. Its also the single most expensive
hardware component on my rocket by a factor of 3. For the long term business
case to work I need to get the single 6” 24 foot tube cost ready to fly under $2K.<span style="mso-spacerun: yes;"> </span>A die cast aluminum inner with a saddle
jacket outer made from injection molded saddle and thin wall extruded aluminum
outer is a rocket motor with a cost of under $200.00<span style="mso-spacerun: yes;"> </span><span style="mso-spacerun: yes;"> </span>So for
the next generation of motors I’m going to abandon the 3D printed motors…<br />
The first rocket motor I designed my self, and the 2nd liquid rocket motor I ever fired was saddle jacket, and this generation will be as well. <a href="https://www.youtube.com/watch?v=GryfvPoRN5Q">(113 Sec Fireing) </a><br /><br /> I’ll use machined aluminum done on my CNC lathe /mill as a stand in for di-cast
aluminum. And the Saddle will either be machined aluminum or possibly machined polyethylene
as a stand in for injection molded. </div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br />
<br /><br style="mso-special-character: line-break;" />
<!--[if !supportLineBreakNewLine]--><br style="mso-special-character: line-break;" />
<!--[endif]--><o:p></o:p></div>
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com76tag:blogger.com,1999:blog-36913768.post-4106627171224845262018-12-15T06:47:00.000-08:002018-12-15T06:47:51.299-08:00Fusion360 cad beg...I'm tryingto convert from Rhino to fusion 360.<br /><br />The following was done in rhino, I'm trying to learn how to do the same in fusion...<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-bE5eu8mwuaQ/XBUH7e_ZTlI/AAAAAAAAP5Y/KSvB2VcR3R0yVepN-HkyNRur4edzi4kSwCLcBGAs/s1600/pic1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1059" data-original-width="688" height="320" src="https://2.bp.blogspot.com/-bE5eu8mwuaQ/XBUH7e_ZTlI/AAAAAAAAP5Y/KSvB2VcR3R0yVepN-HkyNRur4edzi4kSwCLcBGAs/s320/pic1.png" width="207" /></a><br />I can easily draw this in fusion a Extruded cylinder with a hole in it.<a href="https://3.bp.blogspot.com/-ITmfAg34qcA/XBUH75wRt0I/AAAAAAAAP5g/H6O6-1v4K88dvTnngi9vffNS1bwcF4x6ACLcBGAs/s1600/pic2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="944" data-original-width="1600" height="188" src="https://3.bp.blogspot.com/-ITmfAg34qcA/XBUH75wRt0I/AAAAAAAAP5g/H6O6-1v4K88dvTnngi9vffNS1bwcF4x6ACLcBGAs/s320/pic2.png" width="320" /></a><br /><br />I Can also draw my o-ring groove in fusion....</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-va4Ffztdsu4/XBUH8GK0noI/AAAAAAAAP5k/of53SyOxyBs_GOmu8ftoyR4T9XnWrF08gCLcBGAs/s1600/pic3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="876" data-original-width="1193" height="234" src="https://3.bp.blogspot.com/-va4Ffztdsu4/XBUH8GK0noI/AAAAAAAAP5k/of53SyOxyBs_GOmu8ftoyR4T9XnWrF08gCLcBGAs/s320/pic3.png" width="320" /></a><br /><br />In Rhino I next draw two spheres.....(Blue and green)<br /></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-_tsKDXKcUMM/XBUH8WV2sMI/AAAAAAAAP5o/QbAsiRopueo6t87aK91DYS2TVTVt2-3bACLcBGAs/s1600/pic4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1017" data-original-width="961" height="320" src="https://3.bp.blogspot.com/-_tsKDXKcUMM/XBUH8WV2sMI/AAAAAAAAP5o/QbAsiRopueo6t87aK91DYS2TVTVt2-3bACLcBGAs/s320/pic4.png" width="302" /></a><br /><br />Then I generate the line where the spheres intersect the cylinder.<br />(Inner intersection lines have been removed for clarity)<br />(I did this twice and the blue/green colors swapped sorry for the confusion)</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-LvwdiVOnwLA/XBUH7ZyUxXI/AAAAAAAAP5c/1QwjzkjkykomfshZd2M_wi2BAQXiNflJACLcBGAs/s1600/Pic5.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="957" data-original-width="1143" height="267" src="https://3.bp.blogspot.com/-LvwdiVOnwLA/XBUH7ZyUxXI/AAAAAAAAP5c/1QwjzkjkykomfshZd2M_wi2BAQXiNflJACLcBGAs/s320/Pic5.png" width="320" /></a><br />I then use the sweep2 command in Rhino to make a solid from o-ring profile and the two "Rails"<br />This is correctly tangent to the cylinder surface and has the correct o-ring breaks, radis etc...</div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-i7QjSslnW9o/XBUH7coON-I/AAAAAAAAP5U/xMrJE1l5LDctdyOUqFAVj5rws-FoW0OUACLcBGAs/s1600/Pic6.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1082" data-original-width="1418" height="244" src="https://4.bp.blogspot.com/-i7QjSslnW9o/XBUH7coON-I/AAAAAAAAP5U/xMrJE1l5LDctdyOUqFAVj5rws-FoW0OUACLcBGAs/s320/Pic6.png" width="320" /></a><br />Then subtract the solid and I have my o-ring grove.<br /><br />So my fundamental fusion 360 issues....<br />I can't draw the spheres based on points, only dimensions. The lower dimension is easy to derive its the hole radius +the oring offset. The outer sphere is a lot harder as the oring groove sides are not straight and while I can place a point in the appropriate place fusion won't let me draw a sphere to the point. That problem I could work around with some triganometry, but the 2nd problem I can't seem to solve. I need to create a pair of lines to sweep the pattern, these lines need to be the intersection of a sphere and the cylinder. I can't seem to create this geometry no matter how I try.<br /><br />Advice welcome.</div>
<div class="separator" style="clear: both; text-align: center;">
<br /><br /><br /><br /></div>
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com19tag:blogger.com,1999:blog-36913768.post-59884784193310144322018-11-19T12:26:00.000-08:002018-11-21T10:15:47.561-08:000.018" matters...I had a batch of end caps machined for the Carbon tube tank.<br />
This was 4" outer, 0.035 metal liner 0.009 poly bag, and 0.004 gap.<br />
This was all carefully measured and tested, it works well...<br />
<br />
I thought I could reuse these end caps in the 4" 035 wall tube, alas I neglected to account for the bag.<br />
The 0.009 on both sides or 0.0018 in diameter is enough that the caps don't seal correctly.....<br />
Grumble Grumble....<br />
I could line the aluminum tube with the bag and continue....<br />
<br />
<br />
Not a huge deal, but I thought I had enough for 3 sets of flight hardware, now I have zero...<br />
I need to machine new ones...<br />
<br />
So even with the loose fit, I thought I'd assemble the tank and hydro test one.<br />
The end cap retention failed at 420PSI. The cap retaining screws failed in shear.<br />
In hind sight I did not use enough screws, according to the screw stress calculations they should have failed at 390 psi.<br />
<br />
<br />
So all in all its nice to actually be building and assembling hardware again.<br />
<br />
So Mariellen's garden got its first dose of hydro test water, in about 4 years.<br />
<br />
Wednesday morning update...<br />Rebuilt the test tank, used more screws, hydro ed<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-q4VOtoI9rbw/W_WgzCYnqjI/AAAAAAAAPyw/xKME7pRxlWYDfjFq_THo7E_vxbsVJEdMwCKgBGAs/s1600/IMG_20181121_073050.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://1.bp.blogspot.com/-q4VOtoI9rbw/W_WgzCYnqjI/AAAAAAAAPyw/xKME7pRxlWYDfjFq_THo7E_vxbsVJEdMwCKgBGAs/s320/IMG_20181121_073050.jpg" width="240" /></a></div>
to 600 PSI without failure.<br />
<br />
<br />
<br />
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com17tag:blogger.com,1999:blog-36913768.post-11904768651363960152018-11-15T16:04:00.000-08:002018-11-15T16:04:20.364-08:00Fill Drain how to make safe...One way to fill a tank... (and how I've filled every rocket tank to date)<br />Is just put a removable fitting on the top of the tank and pour in the propellant.<br />Its real hard to make a system lighter than just a single AN cap.<br /><br />This has several problems...<br />
<ul>
<li>It does not scale, in a Otrag vehilce you might have 128+ tanks to fill.</li>
<li>On a biprop vehicle, once one of the propellants is loaded loading the other propellant becomes a hazard.</li>
<li>Its very difficult to precisely fill to exact levels.</li>
<li>It does not help you drain after an abort scenario.<br /><br />So I'd like to do remote fill and drain on the vehicle without adding a bunch of weight...<br />Here is one possible scheme that can be done with a single tank penetration.</li>
</ul>
<div>
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-Xlzsq0WmdAE/W-4G_qOopGI/AAAAAAAAPwo/5vifl0qdZEsIT-9nBv28nGsYa7lRv-BMgCEwYBhgL/s1600/FillDrain0.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://2.bp.blogspot.com/-Xlzsq0WmdAE/W-4G_qOopGI/AAAAAAAAPwo/5vifl0qdZEsIT-9nBv28nGsYa7lRv-BMgCEwYBhgL/s640/FillDrain0.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-tpyzJcm2XXs/W-4G_onz0fI/AAAAAAAAPws/yZSh4Nu_k3kboS7puth0_iyeZNEJXco8wCEwYBhgL/s1600/FillDrain1.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://3.bp.blogspot.com/-tpyzJcm2XXs/W-4G_onz0fI/AAAAAAAAPws/yZSh4Nu_k3kboS7puth0_iyeZNEJXco8wCEwYBhgL/s640/FillDrain1.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-pPGHxo23wPM/W-4G_looD_I/AAAAAAAAPww/a1imA2rZPCwVmg9B8yGBE48bL82ZeQX6ACEwYBhgL/s1600/FillDrain3.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://3.bp.blogspot.com/-pPGHxo23wPM/W-4G_looD_I/AAAAAAAAPww/a1imA2rZPCwVmg9B8yGBE48bL82ZeQX6ACEwYBhgL/s640/FillDrain3.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-K1i25-eUg6w/W-4HAmBZkMI/AAAAAAAAPww/j0f6eAKgOyIy6Ygt1uuG4uEVjskbV3ilgCEwYBhgL/s1600/FillDrain4.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://2.bp.blogspot.com/-K1i25-eUg6w/W-4HAmBZkMI/AAAAAAAAPww/j0f6eAKgOyIy6Ygt1uuG4uEVjskbV3ilgCEwYBhgL/s640/FillDrain4.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-patdXBnXtOA/W-4HBHEWzPI/AAAAAAAAPw4/UnR8_F6kxssCXTjNpCgfeG0Qzf5DQB-sQCEwYBhgL/s1600/FillDrain5.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://1.bp.blogspot.com/-patdXBnXtOA/W-4HBHEWzPI/AAAAAAAAPw4/UnR8_F6kxssCXTjNpCgfeG0Qzf5DQB-sQCEwYBhgL/s640/FillDrain5.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-NvEiYFJh1lY/W-4HBnfe8II/AAAAAAAAPw4/55SRcZ3BDaodSNYzoUg5uwID1uEw13U2wCEwYBhgL/s1600/FillDrain6.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://4.bp.blogspot.com/-NvEiYFJh1lY/W-4HBnfe8II/AAAAAAAAPw4/55SRcZ3BDaodSNYzoUg5uwID1uEw13U2wCEwYBhgL/s640/FillDrain6.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-dPAigzcFNKw/W-4HCOmocUI/AAAAAAAAPw0/i5NSK125AvoEf6gIN6E6ddWVWT7l10oNACEwYBhgL/s1600/FillDrain7.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://4.bp.blogspot.com/-dPAigzcFNKw/W-4HCOmocUI/AAAAAAAAPw0/i5NSK125AvoEf6gIN6E6ddWVWT7l10oNACEwYBhgL/s640/FillDrain7.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-YyFhHPVXcYA/W-4HCuNbOpI/AAAAAAAAPw4/PeELQepbwD0O8FgPIMs8IYs7pp5C2JPuwCEwYBhgL/s1600/FillDrain8.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://1.bp.blogspot.com/-YyFhHPVXcYA/W-4HCuNbOpI/AAAAAAAAPw4/PeELQepbwD0O8FgPIMs8IYs7pp5C2JPuwCEwYBhgL/s640/FillDrain8.png" width="494" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-rSS5MfQBLKY/W-4IBKEI6UI/AAAAAAAAPxE/qEzWogzV0d8RHDUN0d3CzSrLmFIie4otQCEwYBhgL/s1600/FillDrain9.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://3.bp.blogspot.com/-rSS5MfQBLKY/W-4IBKEI6UI/AAAAAAAAPxE/qEzWogzV0d8RHDUN0d3CzSrLmFIie4otQCEwYBhgL/s640/FillDrain9.png" width="494" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-sDyIgcmCs6g/W-4IBH3aeSI/AAAAAAAAPxI/F7qeqqMGi5QDHKXU_1cYazoVQySgSwcnwCEwYBhgL/s1600/FillDrain10.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1237" height="640" src="https://4.bp.blogspot.com/-sDyIgcmCs6g/W-4IBH3aeSI/AAAAAAAAPxI/F7qeqqMGi5QDHKXU_1cYazoVQySgSwcnwCEwYBhgL/s640/FillDrain10.png" width="494" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
At the expense of wasign some propellant it ensures the system is filled to a precise level (the level of the bottom of the dip tube, and only requires one tank penetration.<br /><br />It has the added advaltage that if you use the valve RV1 to vent the tank in an in flight abort, it does nto vent the all the propellant, only the pressurization gas.... With Lox its not an issue to dump propellant while in the air, with H2O2 dumping in the air can start a large area brush fire.<br /><br /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div>
<br /></div>
<br />
<br /><br /><br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com24tag:blogger.com,1999:blog-36913768.post-53187493366085704452018-11-13T14:22:00.003-08:002018-11-13T14:22:57.753-08:00Random misc stuff...Lots of little things....<br /><br />It looks like the Fuel in 20Kg lots is about 50% lower cost.<br />If one eventually gets to ton quantities then its down to 18% of the present cost.<br />So all of that is good news....<br /><br />I've been thinking that I was going to have to manufacturer my own quick disconnects.<br />Everything I'd found was either too big, to heavy or to expensive.. (often all three)<br /><br />After a help me beg on Arocket a friend pointed me at some things on E-bay that eventually led me to these...<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-oIIWEfMspDI/W-tM2VIO9QI/AAAAAAAAPvc/-6S7LiSsbDYcD192rHRKD4hPOGsqus-sQCLcBGAs/s1600/QDs.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="852" data-original-width="1029" height="264" src="https://1.bp.blogspot.com/-oIIWEfMspDI/W-tM2VIO9QI/AAAAAAAAPvc/-6S7LiSsbDYcD192rHRKD4hPOGsqus-sQCLcBGAs/s320/QDs.png" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
</div>
<div style="text-align: left;">
They are Aluminum, with viton and stainless internals. Off the shelf and not too expensive. The Really cool part is the rocket side is only 49gm!<br /><br />They are available from multiple places look for FBM3314 and FBM1153. The only way they could possible be better is if they were AN fittings rather than pipe, and availible in multiple sizes. (For all of you that don't do high pressure plumbing, please realize pipe threads are horrible.)<br /><br />In Pauls pantheon of pliumbing....<br /><ul>
<li>Last choice is pipe thread.</li>
<li>AN flare fittings are ok to pretty good. Probably not good enough for directly hazardous materials near people. </li>
<li>Swageloc are good, but both pricey and heavy.</li>
<li>The Big boys use stainless and all orbital welded connections...</li>
</ul>
<div>
That's it for Today....</div>
</div>
<div style="text-align: left;">
<br /></div>
Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com17tag:blogger.com,1999:blog-36913768.post-22739101637682775142018-11-10T14:30:00.001-08:002018-11-11T18:59:16.136-08:00Two chemists walk into a bar, the first one says I'll have H20, the second one says I'll have H2O too... he dies....<br />
<br />
Anyone that has followed my rocketry stuff for awhile knows I like H2O2.<br />
(See comments on H2O2 at the very end of this post)<br />
Both <a href="http://hydrogen-peroxide.us/history-US-Beal-Aerospace/BA-2_stage-2-hot-fire.jpg"> Beal </a>and the <a href="http://www.astronautix.com/b/blackarrow.html">British Black A</a>rrow group did some really cool stuff with H2O2.<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-Mjx1A1UDASg/W-dTrawMcMI/AAAAAAAAPt8/BD_5AU5sETgwDfzLGjdvLN-kLo3aTxJPgCLcBGAs/s1600/EngineCartoonColored.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1237" data-original-width="1600" height="494" src="https://4.bp.blogspot.com/-Mjx1A1UDASg/W-dTrawMcMI/AAAAAAAAPt8/BD_5AU5sETgwDfzLGjdvLN-kLo3aTxJPgCLcBGAs/s640/EngineCartoonColored.png" width="640" /></a></div>
So I've been thinking about engine cycles....<br />
<br />
<br />
<br />
<h2>
<b>A:Regen Cat Pack </b></h2>
is what I have been running for the past few years. H2O2 comes in cools the engine, goes through a CAT pack and then ignites the fuel injected below the cat pack.<br />
This works reasonably well, it has the following drawbacks...<br />
1)CAT pack limits the H2O2 concentration to about 85%.<br />
2)The CAT pack has a lot of pressure drop.<br />
3)Cat Packs wear out or get contaminated.<br />
4)They are some what expensive (Pure or plated silver screens)<br />
<br />
<h2>
B normal chamber with hypergol (or not)fuel.</h2>
<div>
I've been given some evidence of an available decent performance hypergol for H2O2.</div>
<div>
I've not tested it or fired it personally. (Hypergol means fuel and oxidizer light on contact)<br />
Its basically a traditional regen rocket motor. It needs a traditional injector, so not sure if I'll build a <a href="https://en.wikipedia.org/wiki/Pintle_injector">pintile</a>(<a href="https://www.youtube.com/watch?v=y5Nj7Aorjrw">My fireing</a>) , or a shower head <a href="https://www.youtube.com/watch?v=cjQ0yxix4ek">(my fireing)` </a>I've build and fired both with Lox Alcohol before I switched to H2O2.<br />
<br />
This allows one to run to 100% H2O2 and to reduce the pressure drop.</div>
<div>
The primary drawback is the fuel in small quantities from a chemical supplier is about $425 a liter.<br />
The O:F is 4.9 so the fuel for a full Class 2 burn is about $1300 For a full Class 3 burn that is 27K, its starting to hurt.... The H2O2 for the same class 3 burn is $4500 so not totally out of the ballpark..<br />
<br />
There has been an experiment that I've wanted to run for a very long time. I've wanted to try and run a wet, no catpack H2O2 engine. I've always wondered how to get it lit. I think that at some point In testing I'll set up to use the Expensive Hypergol to light the motor, much like TEA/TEB is used in Lox RP engines and see if it continues to run well once the hypergol slug is gone.</div>
<div>
<h2>
C Odd choices....</h2>
<div>
There is some literature in the world talking about H2O2 gas generators with partial pre-decomposition and thermal decomposition of the full flow. This is the schematic of what I Imagine this might look like.... The H2O2 combines with a small amount of the hypergol to get warm, but not enough to "Burn" all the oxidizer....(This could also be part of the H2O2 flow goes through a cat pack to get hot) This then enters into a stack of inconel screens, sort of like a cat pack, but not chemically active, its just a place to warm up and cause thermal decomposition...</div>
<div>
Before thinking about the hypergol I'd planned to run this test with a silver cat pack and 100% peroxide, the silver cat pack would quickly melt and die, but probably not before getting the inconel screens hot enough to do thermal decomposition.... It seems the screens to do decomposition must get to and maintain at least 600C.<br />
<br />
The big drawback to all the thermal decomposition schemes is that hot H2O2 vapor can detonate if it does not decompose.</div>
</div>
<br />
<h2>
Why am I posting all this stuff to the blog...</h2>
<div>
<div>
<h2>
</h2>
<ul>
<li>One of the primary goals for Unreasonable Rocket , from the very beginning is to excite people to try and do cool rocketry things themselves. It does not take NASA levels of $$.</li>
<li>I'm pretty much doing this project by myself in my Garage and at FAR. Last time I did this my Son was helping me, now I'm doing it solo. So using this as a portal to interact with people and maybe inspire people to help with the project is part of the blogging. </li>
<li>Trying to establish a habit of keeping the world up to date, I've set up a Patreon account (I've not turned it on yet) and when I do my first firing in this development cycle and have cool video to share I'm going to turn it on. (If you think I should activate it now say so...)<br /><br />If you want notification of new posts here, I will be announcing them on twitter. I'm @unrocket</li>
</ul>
<div>
<br /></div>
</div>
</div>
<div>
<h2>
*Comments on H2O2 aka hydrogen peroxide.</h2>
The hydrogen peroxide that sits in your medicine cabinet and that you put on your cuts is 3 to 5%. Meaning its 5% H2O2 and 95% water, The H2O2 were talking about here is at least 85%.<br />
<br />
This high strength peroxide decomposes exo-thermally to steam and hot oxygen.<br />
Any concentration above 72% has enough energy to full vaporize the water content and is thus a hazard as it can make lots of hot gas quickly.</div>
<div>
<br />
This decomposition needs some thing to induce it, heat, or a catalyst chemical.<br />
<ul>
<li>Thermal decomposition.</li>
<li>Metal reusable catalysts (silver, platinum)</li>
<li>Consumable Catalysts like the permanganates, etc...</li>
</ul>
With 85% you can run it through a silver catalyst (CAT Pack) for a very long time.<br />
At 90% long term use will melt /degrade silver. Above 90% Silver does not last very long at all as the decomposing H2O2 melts it away, 98,99 or 100% has a more energy and higher performance as a rocket oxidizer.<br />
<br />
<br />
<br />
<br /></div>
Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com32tag:blogger.com,1999:blog-36913768.post-30986039731293337512018-11-09T15:09:00.001-08:002018-11-09T15:09:53.033-08:00Starting with the basics...<br />What is the tank layout?<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-5x5HBl2NMJY/W-YO8L8XsRI/AAAAAAAAPtw/mF-x5ZDcynQ_zdBV4vXVHULEExYtj3NdgCLcBGAs/s1600/TankDiag2.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1237" data-original-width="1600" height="494" src="https://1.bp.blogspot.com/-5x5HBl2NMJY/W-YO8L8XsRI/AAAAAAAAPtw/mF-x5ZDcynQ_zdBV4vXVHULEExYtj3NdgCLcBGAs/s640/TankDiag2.png" width="640" /></a></div>
For control authority you really want the center of gravity (CG) as far forward as possible.<br /><br />So I sketched up the 5 tank layouts shown above...<br />I fully accounted for the weights and moments for all the fittings down tubes, up tubes etc...<br />for the full rocket...I estimated engine and gimbal weights base don stuff I've already fired...<br /><br />I wrote a C++ program where I could instantiate parts, add them to the rocket, then run the tank to depletion and calculate the CG....<br /><br />I modeled #1, #4 and #5 #1 has the farthest forward CG, but was heaviest. If I ballast #4 by adding nose weight until it matches #1 then the CG is farther forward with #4 at the same weight at the extremes of the flight. <br /><br />#1 goes from 152 to 255 cm from the front.<br />#4 ballasted to the same weight goes from 233 to 251 cm.<br />Its much simpler to build and the nose ballast can become more recovery gear bigger batteries, better telemetry etc...<br /><br />As an added benefit #4 is much simpler to build and cleaner aerodynamically with no external feed tubes. I could do #4 with internal feed tubes, but then all the bulkheads become 5 axis machining projects, where for #4 they are all basic lathe parts.<br /><br /><br />I've simulated this rocket 3 ways...<br />My own written from scratch simulator in C/C++.<br />Using RAS Aero II<br />Using OpenRocket...<br /><br /><br />All of the results agree and all say I have enough margin to cross the von-carmen line with a class 2 rocket... It will be interesting to see if I can build it as light as I think I can.<br /><br />That's all for now...<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com17tag:blogger.com,1999:blog-36913768.post-63165288279782745842018-11-02T12:12:00.000-07:002018-11-05T16:08:43.734-08:00All the things.....<br />
A stream of thoughts on the task at hand...<br />
<br />
Starting at the front of the vehicle....<br />
<br />
<br />
I<b>n front of the vehicle, aka airspace...</b><br />
<br />
To start with FAR has a standing waiver for all class 2 rockets to at least 50Kft.<br />
<br />
Once its time to exceed that altitude I strongly suspect that waivers requested from the FAA <br />
with only the required class 2 information will be rejected as this vehicle will have performance capabilities that exceed what was envisioned for class 2. The next launch location after FAR will depend heavily on what the FAA is going to want for a waiver.<br />
Possible locations: Black Rock, Space port in NM, offshore either in the pacific or in the gulf.<br />
<br />
<br />
<b>The nose cone</b><br />
Before I shut down this effort last time, I made some 4" nose cone patterns and John Newman made some molds. So he has all the tooling to make a nice light mixed glass/carbon nose cone for this.<br />
The nose cone has dual requirements, it needs to handle the peak impact temperature and also be radio transparent for GPS and telemetry.<br />
<br />
<b>The primary electronics GNC board.</b><br />
NetBurner is about to release a new module based on the Microchip arm Cortex M7. I will repackage the core electronics from our new module into a GNC/autopilot. Basic features will be:<br />
<ul>
<li>Cortex M7 cpu with hardware floating point.</li>
<li>GPS, will use Ublox until we exceed the ITAR limits.After the ITAR limits become a problem I may switch to the SDR GPS I've test flown, or one of several other GPS solutions I've got working beyond ITAR on the GPS simulator.(I have a LabSat GNSS simulator)</li>
<li>Integrated IMU </li>
<li>Barometer</li>
<li>Pyro drive electronics.</li>
<li>Telemetry Radio (Probably an xbee socket)</li>
<li>LIN communications channel.</li>
<li>CAN communications channel.</li>
<li>I2C communications channel to talk to :Digikey 223-1507-5-ND pressure sensor.</li>
<li>SDIO/SPI interface to SD card interface.</li>
</ul>
<div>
<b>Black Box</b></div>
<div>
A package containing a micro SD card in foam inside some kind of crush resistant vault.<br />
I expect the Telemetry data to be limited and this will be the primary "Product" from the flights.<br />
<br />
<b>Recovery Tracking:</b><br />
The simplistic solution is to add a simple beeper transmitter....<br />
The more complex solution is to use telemetry...(Probably means putting a 2nd tiny GPS on back side of nose cone so it can receive positions on the way down).</div>
<br />
<br />
<b>Camera</b><br />
For flights with recovery I'll use a gopro session.<br />
For flights where recovery is not expected I'll use a 70 cm ATV TX and a atenna with gain on the ground. To simplify things, telemetry may be on the ATV audio channel.<br />
<br />
<br />
<b>Recovery:</b>This vehicle is lighter when depleted that the HPR I tested all the GPS modules on.<br />
For FAR area flights where I'm altitude limited and well withing the atmosphere I'll include the HPR recovery system I've used reliably. This system weighs as much as the rest of the vehicle, so its not a choice for high altitude flights.<br />
<br />
For high altitude flights I'll probably just eject the nose cone at altitude with a simple kevlar strap/streamer to orient the nose cone. Basically no recovery.<br />
<br />
<b>Tanks</b>The notional OTRAG vehicle uses the carbon tanks that John Newman and I developed three years ago. That tanks uses a carbon sleeve with a poly bag liner and machined aluminum oring sealed end caps. This vehicle will use 0.035 wall 6061 T6 4" tube.<br />
I've ordered 24 ft of this tube (arrives on 11/6)<br />
The only thing remaining to decide here is tanks closure. I have two competing concepts....<br />
This will be the very firts hardware I build and hydro test...<br />
In the next month I'm going to make a few 12" long tank sections to evaluate weight and closure...<br />
<br />
Machined domes with oring groves retained by a collar screwed or flush riveted in behind the dome.<br />
<br />
Hydro formed domes welded into the tank ends. This will probably not work as it weakens the underlying material too much, and its very hard to heat treat thin wall tanks.<br />
<br />
Hydro formed domes welded into a collar that slips into the tank end and is itself welded to the tank.<br />
This would involve building a heat sink that clamps on the aluminum tube trying to minimize the heat effected zone. The length of the collar would be whatever is necessary to move the weld beyond the HAZ. On a pressurized tubular tank the lengthwise stress is half the maximum stress in the other direction. So if you can move the HAZ to the point it only effects lengthwise stress its a win.<br />
<br />
<b>Mid Tank Coupler.</b><br />
The mid tank coupler is going to be a some what complicated piece, it will have the roll control nozzles and solenoids built in. It will also structurally join the propellant tanks to the blow down tank on the bottom of the vehicle. The module will have its own local electronics with rate sensor and solenoid drivers. It will communicate with the primary controller on the single LIN backbone.<br />
Its possible that it might also be the fill and drain interface for everything.<br />
<br />
<br />
<b>Main propellant Valves.</b><br />
Three choices here:<br />
OTS aluminum ball valves with external drop off actuators.<br />
This has the possible benefit that one could mount a monprop engine and do hovering stability tests under the fork lift.<br />
<br />
Some version of my Spectra melted string actuators.<br />
<br />
Some version of a pyro valve.<br />
<br />
Pyro or spectra shut off valve.<br />
<br />
<br />
<b>Gimbals and TVC actuators.</b>I have a design for a gimbal with built in fluid channels. This is an intricate little piece 3D printed and post machined. All in all its probably 40 hours of fabrication, each....<br />
Its light, compact and easy to gimbal.<br />
<br />
The alternative is a simple rod end bearing assembly like the LLC vehicle used with flexible hoses. This is easy to fab, but I'm concerned about its impact on the size/wt of the gimbal actuators<br />
and actuator batteries. Pressurized flexible hoses are stiff and require strong actuators.<br />
<br />
For actuators I'm going to use OTS brushless servos.<br />
<br />
<br />
<b>Rear End electronics:</b><br />
Another custom electronics board.<br />
CPU<br />
Two axis rate sensors.<br />
Actuator driver logic. (Probably servo or RS-485)<br />
Pyro drive channels (at least 2)<br />
LIN communication channel.<br />
System simulation will determine if LIN is fast enough to communicate from main GNC to the TVC actuators, it the TVC actuators have local rate sensing. It this is too slow then inter module comm will be upgraded to CAN.<br />
<br />
<b>Thrust Chamber</b><br />
The final thrust chamber here will be smaller and lighter than the 3D printed aluminum chambers I was testing when I stopped rockets 3 years ago. The will otherwise be very similar to the previous efforts. I may build a cat packed based mono prop chamber to allow tethered hover testing of the GNC without risking the vehcile<br />
<b><br /></b>
<b><br /></b>
<b>Rear Fill and Drain</b><br />
The full OTRAG would require rear access fill and drain.<br />
For the single tube test article mid point or top side fill and drain might be advantagous from a getting the weight forward stability stand point.<br />
<b><br /></b>
<b><br /></b>
<b>Batteries</b><br />
The current plan is to have multiple batteries local to each of the the electronics bay, forward/nose cone(GNC And telemetry), mid bay (Roll control) , rear (Main Valves and TVC).<br />
It may prove to be lighter to have a single battery and power distribution, but getting power from the front to the back in an aerodynamically clean way may be more weight than individual batteries.<br />
<br />
<b>Ground support equipment:</b>The necessary transfer tanks, pumps, valves, regulators etc,,,,, to fill drain and pressurize remotely.<br />
<br />
Tracking telemetry antenna.<br />
<br />
Spar buoy to support offshore launches.<br />
<br />
<b>Simulation System.</b>..<br />
I'd planned on using JSB sim when I had other people helping me with things...<br />
I'm currently trying to get that environment running in a way that is useful to me...<br />
BTW Did I ever tell you I hate XML.<br />
<br />
That's enough for one day...<br />
<br />
<br />
A list of random TLA's I might have used...<br />
<br />
CAN -Controller area network, initially developed for automotive communications<br />
GNC - Guidance and navigation control, aka where are we pointing.<br />
HAZ - Heat affected zone, ie a welding term<br />
IMU - Inertial measurement unit<br />
ITAR-International Trade in Arms Regulations aka don't sell ballistic missiles to bad guys.<br />
LIN - Local interconnect Network. A single wire asynchronous communications protocol.<br />
LLC- Lunar lander challenge aka the contest that started Unreasonable Rocket.<br />
OTS- Off the Shelf,ie purchased and unmodified.<br />
SDR- Software defined Radio<br />
TVC- Thrust vector control.<br />
TLA Three letter acronym.<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com12tag:blogger.com,1999:blog-36913768.post-47451266701878945982018-11-01T09:42:00.001-07:002018-11-01T09:42:57.524-07:00Once more unto the breach....<br /><br />I posted this to Arocket and got some questions, so I've modified this text to answer some of the questions and add additional details.<br /><br /><div>
The next unreasonable year...</div>
<div>
<br /></div>
<div>
<span style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">I'm personally at a point where I can take some time off and play with rockets again.</span><div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<i>I don't think I can afford to do my full otrag-lite program, but I can do the next step.</i></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<i><br /></i></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<i>So starting in the January time frame I'm going to be working at least 1./2 time on building a </i></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<i>single tube demonstrator of my otrag-lite concept.</i></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Some changes from the base design:</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Use off the shelf 6061 thin wall 4" al tube for primary tank age rather than the super light carbon tanks I developed. If I get reliable dynamic performance and recovery I might try a carbon tank at the end of the year.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
The rocket is going to be 90% H2O2 with hypergolic fuel.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
I've agreed to not talk about the fuel in return for being able to use it, so don't ask.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Suffice it that I've seen test data that shows it working in a test environment and RPA modeling of the propellant combination shows good isp. Overall propellant density is 1.25. Toxcitiy is more benign than gasoline (what I had been using)</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Vehicle will be blow down.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
For stability reasons the tank-age will be divided in half with pressureant below the propellant tanks.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Every possible means will be made to make it make it light weight.<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
IMHO the most important tool in building a high performance rocket is a precision scale.<br /><br />I'm either going to do externally operated valves or pyro valves still working on that.<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
Vehicle will be at the class 2 limit with really long burn times, lift off thrust to weight on the order of 1.2, with burn times ~180 second`s. actively stabilized and finless.<br /><br />The first version of roll control will be cold gas thrusters between the pressurization tank and the propellant tank. most likely a 3d printed Aluminum assembly. If that uses too much gas, then the next solutions tried would be some really tiny fins at the trailing edge of the vehicle and some "Blades" that deflect into the rocket nozzle.<br /><br />Each area with valves and actuators will have local power and control with the coordination being either a single LIN wire or some form of short range wireless.<br />I believe a single layer of thin copper foil on top of a capton tape for a lin communication channel is probably lightest and lower drag than 3 or four small antennas. My big question here is if the copper tape will stretch as the rocket pressurizes.<br /><br />Telemetry will be through a fiberglass patch on the nose cone.<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
The vehicle should be able to cross the 100 km line.<br /><br />Recovery will be a balute or reinforceed balloon whose sole purpose is to prevent supersonic reentry. I expect the vehicle to be mostly destroyed on each flight. I Might separate the nose cone with camera and data log on its own very small parachute.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
At this point I've secured the long lead items for the project and I'm cleaning up my shop in preparation.<br /><br />In the process of developing the design work based on previous efforts and will probably reopen this blog and start showing designs and hardware around the first of the year.</div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
<br /></div>
<div style="background-color: white; color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: small;">
I'll do the initial testing at FAR until I have issues with their altitude limit. </div>
<div style="background-color: white;">
<span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">Then I will probably be looking to launch offshore.</span><br /><br /><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">My stretch goal is to bring evidence of flown hardware to Space Access this year.</span><span class="HOEnZb"><span style="color: #888888;"><br /><br /><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">CAD/CAM The right tool is probably fusion 360, I tried using it for some projects it about three years ago and it was unusable on a 4K monitor. </span><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">In the last few days I've updated it and it seems much better. My personal tool of choice is Rhino, as I'm really familiar with it , but I'll </span><span style="font-family: Arial, Helvetica, sans-serif; font-size: x-small;">probably</span><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"> to use Fusion 360 as much as possible.</span></span></span></div>
<div style="background-color: white;">
<span class="HOEnZb"><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><br /></span></span></div>
<div style="background-color: white;">
<span class="HOEnZb"><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;"><br /></span><br /><br /><span style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: x-small;">Paul</span></span></div>
</div>
<div>
<span class="HOEnZb"><span style="color: #888888;"><br /></span></span></div>
Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com15tag:blogger.com,1999:blog-36913768.post-28825473419031159692017-10-17T09:36:00.002-07:002017-10-17T10:04:00.630-07:00<div class="MsoNormal">
Paul’s AVC postmortem….<o:p></o:p></div>
<div class="MsoNormal">
In the end it did not go as well as I would have liked. On 6 official attempts I only completed one
lap.<o:p></o:p></div>
<div class="MsoNormal">
I thought I was pretty close to ready; The car was following
complex arced paths well…<br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></div>
<div class="MsoNormal">
<!--[if gte vml 1]><v:shapetype
id="_x0000_t75" coordsize="21600,21600" o:spt="75" o:preferrelative="t"
path="m@4@5l@4@11@9@11@9@5xe" filled="f" stroked="f">
<v:stroke joinstyle="miter"/>
<v:formulas>
<v:f eqn="if lineDrawn pixelLineWidth 0"/>
<v:f eqn="sum @0 1 0"/>
<v:f eqn="sum 0 0 @1"/>
<v:f eqn="prod @2 1 2"/>
<v:f eqn="prod @3 21600 pixelWidth"/>
<v:f eqn="prod @3 21600 pixelHeight"/>
<v:f eqn="sum @0 0 1"/>
<v:f eqn="prod @6 1 2"/>
<v:f eqn="prod @7 21600 pixelWidth"/>
<v:f eqn="sum @8 21600 0"/>
<v:f eqn="prod @7 21600 pixelHeight"/>
<v:f eqn="sum @10 21600 0"/>
</v:formulas>
<v:path o:extrusionok="f" gradientshapeok="t" o:connecttype="rect"/>
<o:lock v:ext="edit" aspectratio="t"/>
</v:shapetype><v:shape id="Picture_x0020_7" o:spid="_x0000_i1026" type="#_x0000_t75"
style='width:278.25pt;height:297pt;visibility:visible;mso-wrap-style:square'>
<v:imagedata src="file:///C:\Users\PAULBR~1\AppData\Local\Temp\msohtmlclip1\01\clip_image001.png"
o:title=""/>
</v:shape><![endif]--><!--[if !vml]--><!--[endif]--><o:p></o:p></div>
<div class="MsoNormal">
This picture is from testing Wednesday The black and pink
arcs are on top of one another.<o:p></o:p></div>
<div class="MsoNormal">
The big change that enabled this precision was to add 200
msec of position prediction to the turn algorithm. IE star turning 200 msec
early (200mse seems to be the command to actual steer servo is in new position
latency)<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-YeF9gpsAwmE/WeYsygjgGzI/AAAAAAAAKws/CMhH86U6AgEARavzaLLpOfx5w6Dy6d78ACLcBGAs/s1600/Path.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="590" data-original-width="618" height="305" src="https://1.bp.blogspot.com/-YeF9gpsAwmE/WeYsygjgGzI/AAAAAAAAKws/CMhH86U6AgEARavzaLLpOfx5w6Dy6d78ACLcBGAs/s320/Path.png" width="320" /></a></div>
As you can see the difference between the black actual path and "pinl desired path is insignificant.<br />
<br />
In addition, with nice straight building walls the laser scanner was correctly
finding the walls and correcting both the horizontal offset and accumulated
heading errors against the walls.<br />
<br />
When I left for Denver on Thursday I had three software bits unfinished….<br />
I’d done testing and analysis on all three, but they were incomplete.<br />
1)Obstacle avoidance.<o:p></o:p></div>
<div class="MsoNormal">
2)Stop at the stop sign/pedestrian.<o:p></o:p></div>
<div class="MsoNormal">
3)Hoop Location.<br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></div>
<div class="MsoNormal">
So Early Friday morning I wrote my barrel avoidance code and got to start testing on the
actual course Thursday…. By 3PM I had my barrel code working the car was going
through the barrel section mostly avoiding the barrels 5/6 times or so….The car
was a bit too large and the barrels were a bit tight so I really needed to go
slow and turn sharply. To make this happen I turned the steering gain way up
for any time the car was in barrel
avoidance mode.<br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></div>
<div class="MsoNormal">
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-kXBerxjmmuI/WeYvIjUS0aI/AAAAAAAAKw4/VjexSIpQJuQqrFYMx0nmC6EJmjCiS471gCLcBGAs/s1600/Path.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="501" data-original-width="577" height="277" src="https://4.bp.blogspot.com/-kXBerxjmmuI/WeYvIjUS0aI/AAAAAAAAKw4/VjexSIpQJuQqrFYMx0nmC6EJmjCiS471gCLcBGAs/s320/Path.png" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<iframe allowfullscreen='allowfullscreen' webkitallowfullscreen='webkitallowfullscreen' mozallowfullscreen='mozallowfullscreen' width='320' height='266' src='https://www.blogger.com/video.g?token=AD6v5dzlh1nIiSwtt8IsydJjBijK4RKH6QLaiRafet1YdJAzGVXLVwb6MG5bmPd6gPOkbvyFdoSWDvxjQg' class='b-hbp-video b-uploaded' frameborder='0'></iframe></div>
Here is a picture and video of the zigzag path through the barrels..<br />
<br />
<br />
I then took some data to figure out how to detect the cross walk the pedestrian
walked on and thus stop at the stop sign. In testing this chunk of code it
worked one time in four or five and I worked on this code until 7:30 pm where I
discovered my error…. I was using a static variable to indicate that I’d
already done the stop and to not do it
again…So the code worked after a clean reset, but not a test restart…<o:p></o:p></div>
<div class="MsoNormal">
Once I fixed that I was reliably stopping at the
pedestrian..<o:p></o:p></div>
<div class="MsoNormal">
I put every thing together and did a full run where
everything worked. Then the course
closed at 8pm and I was done for the day. I had one issue remaining. The start
line was too high it high centered the car, so I had to start behind the start
line and get a running start and jump over the start line.<br />
This basically added 50 to 70” to the path as the wheels spun. I did a hack and added in 70” to the path in
code. I’ll test this in the 2 hours of
testing Saturday morning…<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
<br />
<h3>
Saturday Race Day #1, </h3>
Its cold in Denver and I’m there when
the course opens for practice and rather than use my 70” hack I manually record
a new track path starting 24” behind the start and use that recording to layout a new path.<br />
<br />
I do a test run and the car crashes into the hay bales straight ahead…. And
breacks the 3D printed bracket that held the LIDAR and electronics… I brought spres of every 3D printed object on
the car (6 parts) except the one bracket, because that was not on car #2, that
was metal on car #1.<br />
So with one hour and 15 till race start I’ve got to get the 2<sup>nd</sup> car ready,
it was 100% complete except I had not wired the start switch so I put both cars in the back of the retal
SUV and drive back to the hotel… (about ¼ mi) When I get there I discover the
back gate of the SUV had not closed and neither car was in the car. I went back and found both cars lying in the
road, otherwise undamaged.<br />
<br />
I brought them back to the room and
wired in the start switch on car #2 (I’d planned to do that Saturday afternoon
after day one was done. Rules were I ran one car on Sat, and a different one on
Sunday.<o:p></o:p></div>
<div class="MsoNormal">
I now have 15 min till practice is over and 30 min till my
heat starts and car #2 had not yet been
turned on in Co. I run the test and it
impacts into the same hay bale that broke the previous car. And I remember that my extra 70” hack
was still in place, I remove it and get in one last run it gets tied up in the
barrels, I’m not sure why this is not working….<o:p></o:p></div>
<div class="MsoNormal">
Saturday Heat 1:<br />
I’d planned to spend the morning fine tuning the path to center it up on the
course and perfect it. Alas I spent the morning soldering switches and removing
my 70” hack. <o:p></o:p></div>
<div class="MsoNormal">
Run one it gets a tiny bit hung up in barrels, but otherwise
does the first half of the course, its supposed to go just inside the ramp,
alas the lack of track tuning it hits the ramp/jump and goes off the edge of
the ram, causing it to turn a bit and impact the hay bales on the other side.
End of heat 1.<br />
<br />
<h3>
Saturday Testing between heat 1 and heat 2.</h3>
<o:p></o:p></div>
<div class="MsoNormal">
The car is now acting unreliable. IT runs sometimes, and
other times it just wanders off course in random ways. A couple of times when I try to gain manual
control with the RC receiver it won’t steer….<br />
In trouble shooting this power cycling always seems to fix this… I’m wondering
if I have a hardware problem. Out of 3
or so test runs one works, one is random and one gets hung up in the barrels…<br />
<br />
The main CPU board on the car is a NANO54415, on this car was an old dusty first
rev prototype board that I had used on many projects So I figure there is no harm in swapping the
board.<br />
So I swap CPU boards for the spare in my electronics bag. I reprogram it with
the car code, program in the course and
I’m out of testing time. Time for heat 2….<br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></div>
<div class="MsoNormal">
<h3>
Saturday Heat 2:</h3>
I press the go button it immediately turns right into the wall and dies.<br />
<br />
The system saves a bunch of configurable parameters in flash, one of these is
use the magnetic compass, or just the bare gyro for navigation. I’d found the bare gyro was more repeatable
than the compass, but use compass defaulted to on…. So car turned right into
the wall due to the compass…<o:p></o:p></div>
<div class="MsoNormal">
<br /></div>
<div class="MsoNormal">
Practice between heat 2 and 3 on Saturday…<br />
This went reasonably well, I tuned the path a little bit. <o:p></o:p></div>
<div class="MsoNormal">
Saturday Heat 3:<br />
The car ran pretty much perfectly, it dodged the barrels well, missed the ramp,
caught the hoop and almost stopped at the stop sign. It was supposed to stop within 12” of the
line, it stopped about 18” short, so while it stopped and missed the pedestrian
it it did not get the stop bonus.<br />
<br />
This was the VERY first car to complete the entire cours at this years AVC!<br />
One other car in a later heat also finished the course so only two cars
finished on Saturday.<br />
<br />
So I spend the afternnon bumming some aluminum angle from one of the people
working oon the manned AVC car hack saw off a chunk, drill and tap add some
strategic tye wraps and repair the broken bracket that died earlier this
morning on Car #1.<br />
In general the build and wireing quality of car #1 was better than Car #2 (I
built #2 first) so I was feeling pretty good about Sunday and went out to
dinner with my Wife and my Sister in laws. (One Sister in law flew out with us,
and the other sister in law lives near Denver.).<br />
<br />
<h3>
Sunday Morning..</h3>
I woke up really early Sunday (4am Denver
time) with two things in my mind to accomplish, improve the barrel avoidance to
give the car some more clearance so it does nto drag the sides, and add general
purpose collision avoidance, so that it it some how looses its navigation
position it will steer away from obstacles..<br />
<br />
I code up both these changes The course
opens for testing at 8am, so I put a report screen together on the LIDAR
avoidance and wander around the hallway of the hotel carrying the car and
looking at how it sees and reports obstacles…it works reasonable well…. I take
it out side and try it agains a wall in the parking lot, it works perfectly…
even when command to steer into the wall at a 30 deg angle it will skim along
just avoiding the wall. Its perfect…<br />
<br />
<br />
<h3>
Practice Sunday morning…</h3>
On the first run the new barrel avoidance S/W is perfect. It
doesn’t touch a barrel.<br />
So I take a good manual course survey and set up to fine tune the route…<br />
It starts to act really unreliable… runs some times, doesn’t run others…<br />
<br />
Sunday heat one:<br />
It makes a bad decision on how to go around the very first barrel and gets
wedged between the <br />
barrel and hay bale. In past times this would not have been an issue as it
would push the <br />
barrel aside a little bit and continue.
This run there is so much loose hay on the course that the car just
spins its wheels on the loose hay.<br />
<br />
So while other heats are running on the course I go out in the big empty
parking lot and just run…<o:p></o:p></div>
<div class="MsoNormal">
Something is very wrong its gotten really unreliable…<o:p></o:p></div>
<div class="MsoNormal">
It stops steering in
manual mode even… so I unplug and re-plug the Steering servo and it comes back
to life… for about 30 seconds I do this about three times, and
it comes back to life each time…<br />
Then dies… On the last plug in I plug in the connector off by one pin and put
5V on a 3.3V pin and the CPU power supply dies…<br />
<br />
I rush back to my work table reach into my spare bag pull out a new DEV board…<br />
Oh no the boards on the Car’s have header pins soldered in for the connector,
the spare had just holes, it won’t work…<br />
So I disassemble the CPU dev board from Car #2 and put it on car #1. I take my last spare CPU board from the
useless dev board spare plug it in remount it . I also remove the steering
servo from one car to the other… I’ve got both the steering servo and the dev
board swapped and I have 15Min of testing before the heats start…<br />
<br />
So lets take a break and talk about why I do this… I think its important that a
company eat its own dog food. I’m doing all of this development on a new
NetBurner branch 3.0 it will be our new
multiplatform release, ColdFire, Arm etc… I’m using this new code to find bug
and issues and improve the quality of our new release….this now bites me hard.<br />
<br />
We changed the way that IP configuration and setup works to be all web based
with no special tools. 95% of our testing has been on DHCP based LANS. With a direct cable connection un-configured
the system is supposed to use AutoIP to set up configuration. It has not been
tested recently, and it no longer works…. I can’t talk to the board to download
paths, or set parameters, because it has no IP address….. so I start hacking
the system code to force it to have a
static IP address…<o:p></o:p></div>
<div class="MsoNormal">
(In hind site I could have used the local IPV6 configured
address and solved my problem, but I did not think about that at the time.)
This takes me about 15 minutes to hack in a solution and get the board to boot
with a static IP… (This bug will be fixed before release) Now they are calling my heat I’m out of time…
I program in the path, the config settings and run to the race track. The car
has not even run 1 inch since I swapped the steer servo and the brains… I’m
hoping the servo center is close enough that
the steer PID loop can correct….<br />
<br />
<h3>
Sunday Heat 2:</h3>
The run is almost perfect…<br />
The car goes through the barrels and does not touch anything, it just misses
the hoop by about 3 inches, but it detects the pedestrian, and does an
absolutely perfect stop at the stoip sign, wiatsfor the path to be clear and
continues…<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-QEuh7FLf2so/WeYt_X83WGI/AAAAAAAAKw0/YdUnk0GFjPQUR07_lE8FYoZKzmKRRkIWgCKgBGAs/s1600/IMG_20171015_115755.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1600" data-original-width="1200" height="320" src="https://1.bp.blogspot.com/-QEuh7FLf2so/WeYt_X83WGI/AAAAAAAAKw0/YdUnk0GFjPQUR07_lE8FYoZKzmKRRkIWgCKgBGAs/s320/IMG_20171015_115755.jpg" width="240" /></a></div>
<a href="https://www.blogger.com/blogger.g?blogID=36913768" imageanchor="1" style="clear: right; float: right; margin-bottom: 1em; margin-left: 1em;"></a>It drives all the way around the course to the finish line and stops 3” too
short.<br />
<br />
<br />
<!--[endif]-->
It had been programmed to go about 3 ft past the finish line, alas with all the
hay on the course it got 39” of wheel slip and was 3” short. If it had gone 4”
farther it would have been the hi scoring run of the entire event. This was just crushingly demoralizing…<br />
<br />
Between heat 2 and heat 3. <br />
I extend the stop zone by 8 feet and do a practice run, its perfect…<br />
I turn the speed up 50% and run it again, its perfect….<br />
I park the car and spend the next hour packing up all my stuff into the SUV and
getting ready to go home. I don’t touch the car….<br />
<br />
With everything packed in the SUV, the only thing left to do is run the last
heat and go home. Having not finished the first two heats I’m no longer in the
running to place, I’m half tempted to head out before running the last heat. I
stay.<br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--><o:p></o:p></div>
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;">Sunday Heat 3.<br />
I press the go button the car accelerates hard about 30 ft and then just stops.<br />
When I walk up the speed controller if flashing a red fault light, either it
got to hot (its cool to the touch) or I ran the car battery down to much… (more
likely) my AVC is done.<br />
<br />
Final thoughts:<br />
1)The car was too big for how tight the barrels were. The barrels were much
tighter this AVC than previous AVC;s. I’d chose the chassis to be able to go
insanely fast, I needed rugged more than speed, the lack of ground clearance
and wide stance were both issues. The
Slick tires just don’t work well in straw. The car would be superior on smooth
dry pavement, not so much on the AVC course.<br />
<br />
2)When I turned the steer servo gain way up for the barrels I was driving the
steer servo too hard and it was overheating and shutting down. A normal RC driver
does not continuously drive the servo stop to stop hard, when it barrel following
mode I was doing just that and the servo over temped and died. <br />
Adding in the hyper sensitive obstacle avoidance only made this problem worse…
as the car might change its steering direction mind significantly at 50Hz.<br />
<br />
3)I was not really ready, I should have
had my spares more ready, had a spare for ALL 3D printed parts, had the wireing
done on Car #2. Have tested the barrel mode enough to show the steering servo
flaw etc….<br /></span><br />
<h3>
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;"><span style="font-family: calibri, sans-serif; font-size: 14.6667px;">Conclusion: </span></span></h3>
<br />
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;"><span style="font-family: calibri, sans-serif; font-size: 14.6667px;">Projects with a hard unmoving deadline are painful.</span><br style="font-family: calibri, sans-serif; font-size: 14.6667px;" /></span><br />
<h3>
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;"><span style="font-family: calibri, sans-serif; font-size: 14.6667px;">For general info:</span></span></h3>
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;"><br style="font-family: calibri, sans-serif; font-size: 14.6667px;" /><br style="font-family: calibri, sans-serif; font-size: 14.6667px;" /><br />
</span><br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-Qj3S1lUtAJM/WeY3zJ_VlQI/AAAAAAAAKxI/qB7L7ahoWsYj5gMB-SQfFAdkCsW6lqO0ACLcBGAs/s1600/CarPic.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="1028" data-original-width="1050" height="313" src="https://4.bp.blogspot.com/-Qj3S1lUtAJM/WeY3zJ_VlQI/AAAAAAAAKxI/qB7L7ahoWsYj5gMB-SQfFAdkCsW6lqO0ACLcBGAs/s320/CarPic.png" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-yHj9cqOh6oc/WeY3yyJMpuI/AAAAAAAAKxE/9dCbM8MiGG0Y-GGwAy-TLDl20WDc3TrRACLcBGAs/s1600/IOMap.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="519" data-original-width="743" height="223" src="https://3.bp.blogspot.com/-yHj9cqOh6oc/WeY3yyJMpuI/AAAAAAAAKxE/9dCbM8MiGG0Y-GGwAy-TLDl20WDc3TrRACLcBGAs/s320/IOMap.png" width="320" /></a></div>
<span style="font-family: "calibri" , "sans-serif"; font-size: 11.0pt; line-height: 115%;"><br />
<!--[if !supportLineBreakNewLine]--><br />
<!--[endif]--></span>Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com216tag:blogger.com,1999:blog-36913768.post-78962803687686021452017-08-31T10:55:00.002-07:002017-09-02T09:58:03.254-07:00How to evaluate a Launcher Startup.<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: italic; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">This post started as a </span><a href="https://twitter.com/unrocket/status/903031855892410368" style="text-decoration: none;"><span style="background-color: transparent; color: #4d469c; font-family: "lora"; font-size: 11pt; font-style: italic; font-variant: normal; font-weight: 400; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">7 tweet tweet book</span></a><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: italic; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> . Several people asked me to put it together in a way that can be permanently linked. This is the result.</span></div>
<b id="docs-internal-guid-916ea988-4385-a064-ea3a-e127632841ea" style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I'm assuming there is a valid business case. The business concept with cost estimates and identified customers etc... needs to work before any of this matters. I assume that any business evaluation will include the business fundamentals. I personally believe that a low cost dedicated nanosat launcher makes business sense and I have personally worked on such a business plan. I see a lot of launcher startups being funded so I must assume that others agree the business case might work. </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">What I see looking out at the world is a complete failure in technical evaluation of the various launcher startups. I'm trying to provide a rough guide for technical evaluation of a launcher startup.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To state the obvious, the first goal of any launcher company will be to get payloads into orbit,</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">that is the hard part of the business. Added services, responsiveness, cool features etc... are all irrelevant until you have a vehicle getting to orbit.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So what does it take to get to orbit and how does that differ from getting to space?</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"><img alt="10: Newton's Orbital Cannon - Top 10 Isaac Newton ..." height="300" src="https://lh5.googleusercontent.com/MixN2kUPszaluktb16O-CRJGcH1yN2f4HoGBzyggrs8IZGogqiDoq1_l5ozellxTuK2X3FkbO7zq4xFju0qF4lv9Ppy-P2lscVove4surcD6lE-RHeJY5t-5uypV2tZO0eCC0bHO" style="-webkit-transform: rotate(0.00rad); border: 0.75pt solid #000000; transform: rotate(0.00rad);" width="300" /></span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The official line of space is 100Km or 328K ft. In the scale of the earth a tiny distance. Suborbital vehicles, like Space Ship 1, and Blue Origin's New Shepard are suborbital. They go to space, but they do not go into orbit. This may be useful as a tourist vehicle, and for limited scientific experiments, but its not really relevant if you are trying to build an orbital vehicle. </span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The potential energy necessary to get to space (straight up) is (approximately)</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Pe=m*g*h </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">where m is mass, g is acceleration due to gravity and h is height. So for one kg </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">1*9.81*100,000m = 981,000 nm of energy.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The minimum speed to be in orbit is around 7500 m/sec</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Ke=0.5*m*v^2 </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">so for the same 1 Kg in orbit we add an additional </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">0.5*7500*7500=28,125,000N-m of energy.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> So the total is ~ 29,106,000 NM or 29 times the energy of a suborbital vehicle.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So if a space company says we have gotten to space and we will be in orbit real soon now; realize it's like an airline company offering you a ride from San Francisco to New York City, yet the farthest their plane has ever flown is from SFO to Sacramento. </span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So what does it take to actually get to orbit:</span></div>
<ol style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: decimal; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Mass Fraction (Hard)</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: decimal; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Motor performance (Hard)</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: decimal; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Guidance (Medium Hard and getting easier)</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: decimal; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Regulatory approval (Medium Hard)</span></div>
</li>
</ol>
<b style="font-weight: normal;"><br /></b>
<br />
<h2 dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Mass Fraction.</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Mass fraction is the ratio of propellant mass to empty weight. For example a 2L coke bottle has a mass fraction of about 40. I.e., the bottle full of coke weights 40 times what it weighs empty.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">This is a good mental model for a rocket, the mass ration of the upgraded Falcon 9 is estimated to be 25:1.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Any orbital vehicle using chemical propulsion will look like a big tank.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So when evaluating a potential launcher company you need to ask what is the Mass Fraction of hardware you have on hand and can show me. When evaluating this don't accept paper numbers, insist on knowing what the numbers are for the hardware on hand.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<h2 dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Motor Performance.</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Rocket motors (assuming they work at all) have one major and two minor performance parameters.</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">ISP</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">. It's usually stated in seconds. IE a motor with an ISP of 300 will make 300lb sec of thrust for one lb of propellant.Orbital vehicles have had rocket motors varying in ISP from 220 (shuttle big solids) to 450 (high stress staged combustion Lox/H2 SSME) Lox RP1 motors are in the 300 to 330 range.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Thrust to Weight</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">: What is the ratio of motor weight to motor thrust. If the rocket motor is accounted for in the Mass Fraction of the overall vehicle, this is sort of irrelevant. Its also a bit hard to score as the value varies depending on where you draw the line between the rocket motor and the rest of the vehicle. The Main propellant valves for instance, do they belong to the tank or the Motor?</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: black; font-family: Lora; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Burn Duration</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">: The rocket motor need to last long enough to get you to orbit. This is not really relevant to most liquids, but for small solids, it's really hard to increase this number due to the physics of solid propellant burning and insulation requirements.</span></div>
</li>
</ul>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">I've marked this part of the four fundamentals as Hard. I'd actually score the motor as Medium hard, but getting all the instrumentation and test together to optimize and really know what your motor is really doing pushes this into the hard category. </span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<h2 dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Guidance</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The rocket needs to go where you want it to go. You'll also have to convince the regulatory agencies that you really do have control of where it's going so it won't be a hazard. As computer simulations get better and better getting this part right gets easier. It's really easy to have the simulation right, and have errors in the vehicle where the actuator direction is backwards or the simulation inertia scale is wrong lbs/kg anyone? </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">So, does the rocket company have a plan to verify and reality check the hardware with the simulation without destroying the rocket? I test flew my hovering rockets under a forklift so I could discover guidance errors without destroying the vehicle. The difference between this </span><a href="https://www.youtube.com/watch?v=L-v-F3xnmhU" style="text-decoration: none;"><span style="background-color: transparent; color: #4d469c; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">video</span></a><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> and this </span><a href="https://www.youtube.com/watch?v=ikaxvvFq0Ks" style="text-decoration: none;"><span style="background-color: transparent; color: #4d469c; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">video</span></a><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> is the sign of a single term in the guidance equations.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<h2 dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Regulatory</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">If you're in the U.S. you are going to have to get FAA permission to launch your vehicle.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Where you launch from and how you mitigate risk to the general public are a big part of this process.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">It's not really that hard, it just must be planned for in the development of the vehicle. It's not something you can just "Stick OK" a completed vehicle if you have given zero thought to things like ranges, range safety and EC (expected casualty) The FAA is going to care about what the rocket parts can hit if things do not go to plan. That's why I've always given very little credence to inland spaceports like the one in NM or Odessa as a place for orbital launches. If you launch from NM you're going to stage somewhere over the densely populated parts of Tx. Short of a planet wide emergency, like in Seveneves, it's never going to be allowed.</span></div>
<b style="font-weight: normal;"><br /></b>
<h2 dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Putting it all together with the rocket equation</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The rocket equation </span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Delta V= ln(MI/MF)*ISP*g</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">MI </span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">initial stage mass, ie the weight of everything....including upper stages and propellant</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">MF</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> final stage mass ie the weight of everything minus all the burned propellant.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">ISP</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> the Motor ISP number. (Not really a fixed number improves with altitude)</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt; text-indent: 36pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">g</span><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> 9.81 m/sec acceleration due to gravity.....</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Calculate this Delta V for each stage in the vehicle.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The Mass of the fully fueled stages above the one you are calculating Dv for must be included in both the initial and final weights.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Once you have calculated ALL of the stage Dv and added them up, if the number is > 9000m/sec then you have a chance at getting to orbit. This number will vary somewhat with the vehicle acceleration profile and size. I personally like this paper "</span><a href="https://e-reports-ext.llnl.gov/pdf/321763.pdf" style="text-decoration: none;"><span style="background-color: transparent; color: #1155cc; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: underline; vertical-align: baseline; white-space: pre-wrap;">How Small can a launch vehicle be</span></a><span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">" for evaluating concepts as a first order check.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">If the number is not yet to 9000m/sec and the plan to fix mass fraction and ISP to get to 9000m/sec is not the number one issue for EVERY technical person working on the vehicle, I would be doubtful they will succeed.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<h2 dir="ltr" style="background-color: white; line-height: 1.38; margin-bottom: 0pt; margin-left: -11pt; margin-right: -11pt; margin-top: 0pt; padding: 10.2pt 11.25pt 8.5pt 11.25pt;">
<span style="background-color: transparent; color: #444444; font-family: "arial"; font-size: 10.5pt; font-style: normal; font-variant: normal; font-weight: 700; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The Team</span></h2>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Building a new Rocket is an exercise in creativity. There is not a formula that given inputs generates a rocket. Unless the engineering team shows the ability to design, build, evaluate, and repeat in a creative way, nothing else is going to matter. Building hardware is different than building software, rockets are hardware. When you talk to the CTO/Chief engineer/Chief Wizard without notes can he tell you what his mass fractions, ISP and current achieved weight vs planned weight numbers are?</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">If he can't then who in his organization can? If no one can, then they are not going to succeed.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Walk through the shop and engineering, do you see a scale? Does every engineer building a piece part know what his weight budget is and if he's going to make the weight budget?</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Before XCOR failed, I personally thought about investing in their company several times, every time I got a tour of their facility, I was turned off by the complete lack of weight control. The half finished linx had many parts that look like they belonged on a truck, not a space craft. The complete lack of detailed weight control on all the minor parts spelled failure to me and I never invested for just this reason.</span></div>
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Eventually the team will need to learn operations, and as it grows it will need HR, middle management and all the other parts of a company. But unless it gets the creative engineering part right up front it's going to run out of $$ long before any of these things matter.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To quote from my tweet storm:</span></div>
<ul style="margin-bottom: 0pt; margin-top: 0pt;">
<li dir="ltr" style="background-color: transparent; color: #444444; font-family: Arial; font-size: 10pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Pretty Paint does not matter.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: #444444; font-family: Arial; font-size: 10pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Fancy Building does not matter.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: #444444; font-family: Arial; font-size: 10pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Previous Dinospace experience does not matter. </span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: #444444; font-family: Arial; font-size: 10pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Cool animations of a paper rocket do not matter.</span></div>
</li>
<li dir="ltr" style="background-color: transparent; color: #444444; font-family: Arial; font-size: 10pt; font-style: normal; font-variant: normal; font-weight: 400; list-style-type: disc; text-decoration: none; vertical-align: baseline;"><div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Until they have hardware that can do 9000m/sec DV, operational issues don't matter.</span></div>
</li>
</ul>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: normal; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Why doesn't previous dinospace experience matter? Because other than SpaceX, all of the other launch providers had their creative how do we do the base design done in the 60's and 70's. The creative steely eyed missile men that made that fabulous leap to the moon and beyond are no longer part of the current dinospace environment. It's a very different thing to manage and evolve an existing system than it is to create a new one from scratch.</span></div>
<b style="font-weight: normal;"><br /></b>
<br />
<div dir="ltr" style="line-height: 1.38; margin-bottom: 0pt; margin-top: 10pt;">
<span style="background-color: transparent; color: black; font-family: "lora"; font-size: 11pt; font-style: italic; font-variant: normal; font-weight: 400; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Please feel free to comment on errors or omissions or areas that need clarification in this post. I will try to correct, enhance and improve over the coming few weeks.</span></div>
<br />
<br />
<br />
<br />
<div>
<div>
<br /></div>
<br />
<br />
<br /></div>
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com50tag:blogger.com,1999:blog-36913768.post-66760344864364644172016-06-12T07:15:00.001-07:002016-06-12T07:59:39.102-07:00Slides from Space Access.. 2016Here is a link to my Space Access 2016 slides..<br />
<br />
<a href="https://www.dropbox.com/s/y13kzn5fi6omeen/SA2016.ppt?dl=0">https://www.dropbox.com/s/y13kzn5fi6omeen/SA2016.ppt?dl=0</a><br />
<br />
Some pictures if you don't want to mess with PPT...<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://4.bp.blogspot.com/-85jIehXbZTY/V11tjsufCaI/AAAAAAAAFa8/pevhu1WKnOoAadFisDT3J3Arj7gwaiwxACLcB/s1600/HexAllStage.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="176" src="https://4.bp.blogspot.com/-85jIehXbZTY/V11tjsufCaI/AAAAAAAAFa8/pevhu1WKnOoAadFisDT3J3Arj7gwaiwxACLcB/s320/HexAllStage.png" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://2.bp.blogspot.com/-ApdIrqCJ7EU/V11tl9psKiI/AAAAAAAAFbE/DFHIq6rzKKwPm2g4jS8DPbZDHxXuhTL4gCLcB/s1600/HexSlideStage.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="185" src="https://2.bp.blogspot.com/-ApdIrqCJ7EU/V11tl9psKiI/AAAAAAAAFbE/DFHIq6rzKKwPm2g4jS8DPbZDHxXuhTL4gCLcB/s320/HexSlideStage.png" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-r5mrLE4UWeo/V11t3J-UaEI/AAAAAAAAFbM/39k-ZfInLwwDPniCJQJY42NBvAwpSR4vQCLcB/s1600/MotorFlowVis.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="161" src="https://1.bp.blogspot.com/-r5mrLE4UWeo/V11t3J-UaEI/AAAAAAAAFbM/39k-ZfInLwwDPniCJQJY42NBvAwpSR4vQCLcB/s320/MotorFlowVis.png" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://1.bp.blogspot.com/-G0HmDk-_Vyg/V11uiVy06qI/AAAAAAAAFbY/cor8vZVNKjMJVaLqjKzU1s9tFuQCIxMvgCLcB/s1600/Engine.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://1.bp.blogspot.com/-G0HmDk-_Vyg/V11uiVy06qI/AAAAAAAAFbY/cor8vZVNKjMJVaLqjKzU1s9tFuQCIxMvgCLcB/s320/Engine.jpg" width="320" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-ob-ssAw2oUA/V113uoeWJZI/AAAAAAAAFb4/R07K5yUBrTkOSIrYLPA0UO0jTuPE-Pa-ACLcB/s1600/DSCF0017.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://3.bp.blogspot.com/-ob-ssAw2oUA/V113uoeWJZI/AAAAAAAAFb4/R07K5yUBrTkOSIrYLPA0UO0jTuPE-Pa-ACLcB/s320/DSCF0017.JPG" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://3.bp.blogspot.com/-k8iMf3tZusA/V114w6WjSaI/AAAAAAAAFcE/I_qSO64Oc_0egrAEy3LAH4J9p11QHSPjQCLcB/s1600/DeadMotor.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="https://3.bp.blogspot.com/-k8iMf3tZusA/V114w6WjSaI/AAAAAAAAFcE/I_qSO64Oc_0egrAEy3LAH4J9p11QHSPjQCLcB/s320/DeadMotor.jpg" width="318" /></a></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com55tag:blogger.com,1999:blog-36913768.post-86881027110278793622016-03-10T20:47:00.000-08:002016-03-10T20:47:10.434-08:00An interesting EMC tale..I spent much of the last week doing EMC testing on a new NetBurner module, for FCC and CE qualification. The basic process is you take a unit to the test lab and they do various emissions and immunity tests. This happens with basically every electronic product you ever purchase.<br /><br />This week we had an odd result that is worth of a write up...<br />Most EMC tests start with emissions testing as that is the most often failed part so get that done first.<br />
<br />
One of the tests in the middle is Radiated Immunity...<br />
For normal consumer products they put the unit in an RF field of about 3V per meter and sweep the frequency. This test is done in a 3M RF chamber and in the place we test this is split into 16 parts....<br />
<br />
Front, back,right, left in each of vertical and horizontal polarity with two sweeps one up to 1Ghz and one from 1 Ghz to 2.7Ghz. Your unit is supposed to remain operational during the test...<br />
So for this new unit a Wifi /Ethernet to serial unit we put a loop back cable between the serial connections and do an ethernet ping and tcp over wifi loop back through the serial connection.<br />
We monitor that data goes out and back and is reliable. Running 2.4Ghz wifi we expect some packet loss when they sweep through 2.4Ghz, but the unit should recover.<br />
<br />
<br />
The first 8 tests under 1Ghz were uneventful....<br />
For over 1Ghz they swap out the drive antenna for a wide band horn and different amplifier.<br />
The first 4 tests, left, right x horizontal,vertical all went well.<br />
<br />
Then we started doing the front and back of the unit and the Wifi in the unit started acting flakey. It would loose the wifi connection and nothing I could do would make it come back. This was with the chamber open and the signal turned off. It seemed like physically moving the unit caused it to die.<br />
I got through one more set, the back, leaving just the front of the unit to test and I just could not get it to work ,,,, So I aborted the testing on Tuesday and drove back to the office from the test lab in orange county.<br />
Since moving the unit caused it to die I assumed a bad solder joint.<br />
When I got back to the office I re-flowed the wifi module and and retested wifh while violently shaking the unit. It worked flawlessly...<br />
<br />
So I went back to the lab on Wednesday, EFT, surge, ESD, conducted immunity etc...<br />
Everything worked flawlessly for the next two days. The WIFI was really solid....<br />
<br />
This afternoon we had one test left >1Ghz radiated immunity to the front, horizontal and vertical...<br />
<br />
The unit fired right up and worked flawlessly....<br />
We finished the horizontal test, the drive was off no signal...<br />
The test technician went into the chamber and rotated the drive horn from Horizontal to Vertical...<br />
WIFI died. I rebooted the unit and nothing I did could make wifi work...<br />
So I asked them to turn off their amplifier.... and the wifi came back to life...<br />
(This is with the drive to the AMP turned off) Amp on wifi dead, amp off wifi works....<br />
<br />
We then rotated the drive antenna back to horizontal and turned the amp on...<br />
Wifi worked.... we rotated the feed horn wifi died...<br />
<br />
The strange part is when the tests were actually running IE they were driving RF energy in to the AMP and out the antenna at our unit WIFI worked flawlessly. It only died when the test set was idle.<br /><br />The WIFI antenna on our unit could be rotated to vertical or horizontal, so as long as that antenna was of opposite polarity to the test antenna everything worked....<br />
<br />
What is even stranger is we could be dead and idle and turn on the test IE drive energy and things worked....<br />
<br />
So we did the last test with the WIFI antenna horizontal..<br /><br />The whole time our unit could scan for the WIFI router and recieve fine, when it tried to transmit things died...<br />So what is going on? The only theory I have is that our WIFI signal was coupling into the amplifier and causing some king of feedback, ie like Microphone squeal...<br /><br />The guys running the EMC lab have been doing this for 30 years and they have never seen anything like it... It was a strange Day...<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com8tag:blogger.com,1999:blog-36913768.post-5479768669194473242016-01-11T14:41:00.001-08:002018-11-05T16:09:13.561-08:00Accelerated GPS musings....GPS L1 is at 1575.42 Mhz.<br />
<br />
The normal GPS CA code chip period is 1msec.<br />
<br />
Most GPS systems integrate for one or more whole Chip intervals dump the results and repeat.<br />
<br />
The hardware typically has a numerical controlled oscillator (NCO) that represents the satellite frequency that is integrated over this time.<br />
<br />
So if we integrate a 1575.42 Mhz signal for 1 msec, how far off can our frequency be before our<br />
phase error is 180 degrees at the end of 1 msec? its about 500hz....<br />
(Which is why the tong or FTP search bins for finding the inital GPS are at 250Hz or so.)<br />
<br />
Most tracking implementations have single value of Frequency driving the NCO....<br />
If you want things to work well then your phase error over one period should be less than 45 degrees... (where Tan is linear) so that is a frequency error of about ~125Hz or a Velocity error of<br />
12 m/sec. So for 1 msec of Acceleration that is a 1200 G, so it should be<br />
<br />
<br />
<br />
<br />
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com5tag:blogger.com,1999:blog-36913768.post-35690557883071328212015-12-21T08:46:00.001-08:002015-12-21T08:46:45.273-08:00Flight of 12 19 15Some background on GPS.... this post is chronologically challenged as it flips back and forth)<br />
<br />
I have three approaches to getting the GPS to work.<br />
They are somewhat related.....<br />
<br />
1)Use a Swift navigation PIKSI with custom firmware.<br />
I've flown this unit with stock firmware twice, and with custom firmware once.<br />
Flight 1 Stock firmware, lost lock at ~5 gee, marginal GPS in all cases.<br />
Flight 2 Custom firmware with wide open GPS tracking loops... over did it as the units were tracking sats that were not there.....<br />
Flight 3a) (12/19/15)<br />
Newer version of Stock firmware GPS performance much improved, still lost lock at 6 gee, but recovered at burnout... <br />
flight 3b)Same flight different piksi hooked up to intel compute stick to log RAW signals from the front end.<br />
<br />
2)Use a RTL SDR dongle with GNSS-SDR and write custom firmware..<br />
Thanks to some help from a follower/friend I have this runnign on the ground with my survey grade 35DB trimble antenna, but not with the flight weight antennas, I'm waingin for some low nosie amps to make this work wiht the flight weight antennas.<br />
<br />
<br />
3)Build my own GPS with full IMU tight integration.<br />
This will use the same Maxim GPS front end as Piksi, but with the Zynq CPU.<br />
I have all the prototype pieces in work....<br />
<br />
After action...<br />
<br />
Thursday, Friday and Saturday I had a bad sore throat and cold.<br />
On Thursday I determined that the RTL-SDR was not going to work without the LNA I did not have.<br />
So I switched to trying to record the raw signals from the piksi...<br />
After napping much of the day Friday to get better I finished the Piksi raw record about midnight Friday.<br />
<br />
Saturday I got up at 4:45 rechecked that everything was working, packed all the stuff into the car and drove to the airport. I took off about 7am in the 182 Headed to FAR , I landed on the private dirt road next to FAR at about 8:15.<br />
<br />
Started prepping the HPR for the flight using one of John Newmans ~M experimental motors.<br />
one of the Altimeters failed the deployment charge conductivity test, took me about 2 hours to find the broken wire down inside the avionics module. Launched the rocket at 11:07:26 It went to ~12K ft. The GPS experiments and batteries added a lot of weight to the nose cone and I did not upgrade the main chute retention nylon bolts. So when the drouge deployed at appogee the main also deployed. After driving around in the desert on the quad for an hour gave up looking for the rocket and switched to the airplane.... it took us about 5 min in the 182 to find the rocket. It was 4 miles from launch and withing 25 ft of a paved road. So we landed back at FAR and Ted took me to get the rocket in his jeep. Kind of fun to ride in a really capable off road vehicle... The rocket barely fit in the jeep and on the way back to far we jumped over a rock pile the rocket came loose and broke Ted's window ;-( When people try to budget projects like this and understand costs no one puts things like Jeep windows in the budget.....<br />
<br />
Once back at FAR I took the GPS modules out of the nose cone, I packed up and flew to Oceanside...(OKB) The flying club I'm part of had its Christmas party Saturday afternoon and I had promised I'd give breezy rides, so I left the 182 at OKB and took the Breezy to CRQ... it was too cold and I had no breezy ride takers.... so I took the breezy back to<br />
OKB put it away and flew the 182 back to CRQ unpacked and drove home. I got home about 6 pm and went to bed early. It was a long day... <br />
<br />
Saturday I downloaded the data from the GPS modules. The SBP format file from the first Piksi is here: <a href="https://www.dropbox.com/s/51yaojhfwg6yvic/LOG00041.TXT?dl=0">SBP format Datafile</a> The SBP format is defined here https://github.com/swift-nav/libsbp/blob/master/docs/sbp.pdf<br />
<br />
Decoding that the Piksi with the current stock firmware lost lock at about 6 gee and regained lock at burn out.<br />
<br />
The second piksi was recording raw RF from the front end via the intel compute stick... from time to time it had a FPGA fifo error and the sampler would restart.... inside <a href="https://www.dropbox.com/s/9wp2fgi3nsikip6/raw.zip?dl=0">this zip file</a> are a bunch of raw data files. The file ending in <span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.8px;">110731 has the first 4 seconds of flight. The File 110822 has the balance of the boost phase. </span><br />
<span style="background-color: white; color: #222222; font-family: arial, sans-serif; font-size: 12.8px;"><br /></span>
<span style="background-color: white;"><span style="color: #222222; font-family: arial, sans-serif;"><span style="font-size: 12.8px;">These dat files are supposed to run in the swift nav peregrine software GPS receiver, alas my linux fu is not working and I'm unable to get peregrine working as it looks like swift has moved its library python bindings from a separate </span></span></span><span style="background-color: white;"><span style="color: #222222; font-family: arial, sans-serif;"><span style="font-size: 12.8px;">module into the libswiftnav, alas that integrated version python will not build on my VM....</span></span></span><br />
<span style="background-color: white;"><span style="color: #222222; font-family: arial, sans-serif;"><span style="font-size: 12.8px;">If anyone wants to play with this you can find info on peregrine here:<a href="http://docs.swift-nav.com/peregrine/installation.html"> Peregrine</a></span></span></span><br />
<span style="background-color: white;"><span style="color: #222222; font-family: arial, sans-serif;"><br /></span></span>
<span style="background-color: white;"><span style="color: #222222; font-family: arial, sans-serif;">That's all for now. I'll update when I manage to get some info from the raw data.</span></span>Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com17tag:blogger.com,1999:blog-36913768.post-60294177201620200602015-12-06T21:06:00.000-08:002015-12-06T21:06:15.274-08:00After Action report...So this was a FAR weekend.<br />
I had intended to do three tests, only got one done.<br />
<br />
I fired the 3D printed motor with larger diameter plumbing on the main valve and a turbine flow meter so I can measure C* and ISP.<br />
<br />
Results are mixed....<br />
The test stand I'm using is an amalgamation of an old test stand and a bunch of valves from the silver ball. In short it is a mess. I worked on making it better this week. (largely why I only got one of my tests done) We hydroed the basic structure and tested the relief valve a few weeks ago, and all of that is solid. The new valves and arrangements form the main outlet to the motor are solid.<br />
<br />
The valves for the fuel side and the pressurization system are 100% Silver ball leftovers.<br />
They largely worked two weeks ago when we ran it, this weekend two of the fuel side valves were frozen and the actuators died. I had one spare actuator with me so I replaced the fuel valve actuator and changed the fuel side vent to manual operations.<br />
<br />
The 2nd deficiency of the system is that all the wiring is an unreliable mess. I hope to clean that up repackage the electronics and make it all a solid solution before I use the stand again.<br />
I left the test stand at FAR but brought all the valves and sensors home.<br />
The actuators are all dynamixel RX-64, 18V actuators run off a 5 cell lipo and an ac power supply to keep things topped up. I have a nice 40V 13.8V AC powered supply, thinking about trading the RX-64 for MX-64 that would be happy running at 13.8V. This is a $1K decision, I need to sleep on that.<br />
<br />
<div>
<br /></div>
<div>
My old sureflow pump for loading oxidizer died this year. I bought an air powered diaphram pump from McMaster car to replace it as the model of sureflow pump is not longer made.</div>
<div>
The problem with this pump is that is really pulses, the flow is not smooth so hoses jump around and do unpredictable things. I mounted the pump to a 3 hp roll around aircompressor and added a remote dead man switch activated valve to turn the pump on/off. I also changed the loading procedure form opening the top of the tank to having a separate valve and a hard connection on the bottom for fueling, no ladders involved. These changes mostly worked as designed and I'm happy with them. much less risk drama in oxidizer loading. I need to do something similar for the fuel side and will do so. I still have hope that I can find a good steady electric self priming oxidizer pump..... I've ordered a couple of candidates, we will see how they turn out.</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
The firing ran well about 78 seconds. The CAT pack worked well and I got good data. The feed pressure was up about 20 psi from last time, the chamber pressure was up about 10, not sure where the other 10psi went.... motor ran at about 180 PSI target is 200. On shutdown the fuel feed pressure stayed up witht he fuel valve closed. So I suspect that rebuilding the fuel side of the system in the mojave dust introduced enough material to clog the fuel orfices. I've ordered a small sintered 10 micron fuel filter to add to the system. Well see when I examine the engine this week....</div>
<div>
<br /></div>
<div>
<div>
I forgot to do a final last minute tightness check on all the plumbing. Got distracted by a rocket launch that required everyone under cover and for got to tighten one pressure transducer... sprayed peroxide all over everything...this part was after the main valve so was not part of the pre-fill leak check.</div>
</div>
<div>
<br /></div>
<div>
Then wheil disassembling things I dumped fuel all over the open ox inlet port on the motor.</div>
<div>
So before I run it again it needs to come apart and be properly lcleaned for oxidizer service.</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
Things to do before next test:</div>
<div>
Rebuild and test all the valves and actuators.</div>
<div>
Package the electronics in a more robust manner.</div>
<div>
Add flow meter to the fuel side.</div>
<div>
<br /></div>
<div>
I'll probably run another motor test the first FAR event of January that should be Jan 2nd</div>
<div>
For the Far event on the 19th of December I'm going to try and fly my GPS experiment and test the little TJ-20A turbine as a potential first stage motor. </div>
<div>
<br /></div>
<div>
I'll try and post some of the test data when I have looked at it later this week.</div>
<div>
<br /></div>
<div>
Paul</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com6tag:blogger.com,1999:blog-36913768.post-13963444872297605192015-11-27T16:32:00.001-08:002015-11-27T16:32:57.102-08:00Working on full layout<div class="separator" style="clear: both; text-align: center;">
Looking at various possible layouts for the bottom of the Third Stage.</div>
<div class="separator" style="clear: both; text-align: center;">
(IE the one where weight really matters....)</div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<br /></div>
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-s1I62PzJ9Uo/Vlj17sntnaI/AAAAAAAAFNA/ehyhvYdMFaM/s1600/BottomOfRocket_11_27_3s.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="311" src="http://3.bp.blogspot.com/-s1I62PzJ9Uo/Vlj17sntnaI/AAAAAAAAFNA/ehyhvYdMFaM/s320/BottomOfRocket_11_27_3s.png" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://4.bp.blogspot.com/-wdnbjDFFOJ4/Vlj176f-ZHI/AAAAAAAAFNE/_bDTD3AIaew/s1600/BottomOfRocket_11_27_4c.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="294" src="http://4.bp.blogspot.com/-wdnbjDFFOJ4/Vlj176f-ZHI/AAAAAAAAFNE/_bDTD3AIaew/s320/BottomOfRocket_11_27_4c.png" width="320" /></a></div>
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-m4U7f5YWoAE/Vlj175VAH4I/AAAAAAAAFNI/BtYBwAKbBQQ/s1600/BottomOfRocket_11_27_4sbv.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="320" src="http://3.bp.blogspot.com/-m4U7f5YWoAE/Vlj175VAH4I/AAAAAAAAFNI/BtYBwAKbBQQ/s320/BottomOfRocket_11_27_4sbv.png" width="285" /></a></div>
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com9tag:blogger.com,1999:blog-36913768.post-40835052316266237162015-11-20T14:40:00.000-08:002015-11-20T14:40:40.481-08:00motor design...Here is a quick note about the Motor we are going to fire on Saturday...<br />
<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="http://3.bp.blogspot.com/-8rySbhmSDS4/Vk-gjbprtyI/AAAAAAAAFMI/UFSN6nu3W5c/s1600/MotorFlowVis.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="321" src="http://3.bp.blogspot.com/-8rySbhmSDS4/Vk-gjbprtyI/AAAAAAAAFMI/UFSN6nu3W5c/s640/MotorFlowVis.png" width="640" /></a></div>
<br />
The Grey is the 3D printed motor.<br />
The Light Blue is the part I turned and machined (4 times)<br />
The Gold is the peroxide going down the cooling passages...<br />
The Red is the peroxide coming back up the cooling passages... (The gold and red connect at the right end of this drawing.<br />
The Green is the Catalyst pack that turns the oxidizer from liquid to Steam and hot Oxygen.<br />
The Yellow in the band around the middle and in (two shown) the four fuel injectors that inject fuel just below the cat pack.<br />
<br />
<br />
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com10tag:blogger.com,1999:blog-36913768.post-79568883248578541442015-11-16T15:49:00.000-08:002018-11-05T16:09:13.732-08:00The big chunks...Trying to do a minimalist amateur sputnik....<br />
We need to build a vehicle light enough with a good enough performance to get to orbit.<br />
We need to make sure we can make it go in the desired direction.<br />
We need to involve the regulatory agency so we can do this legally.<br />
<br />
How do these three base requirments break out into bigger tasks...<br />
<br />
0)Conceptual Design...<br />
Done:<br />
Spread sheet and simple performance model says 4" diameter 16" long OTRAG tube rocket can get to orbit.<br />
<br />
<br />
1)High mass ratio Air frame...<br />
Done:<br />
<br />
<ul>
<li>I have tested representative tanks with the required mass ratio.</li>
</ul>
<br />
In process:<br />
<br />
<ul>
<li>I have one full size sample, I still have to test that.</li>
</ul>
To do:<br />
<br />
<ul>
<li>Finish Detail design of Full Airframe.</li>
<li>Static test one full tube with fill drain, gimbal etc...</li>
<li>Build Cluster.</li>
</ul>
<br />
<br />
<br />
2)Motors...<br />
Done:<br />
<br />
<ul>
<li>Designed Motor and had it 3D printed in Aluminum.</li>
</ul>
<br />
In Process:<br />
<br />
<ul>
<li> Finishing hte machined parts to go with the motor, adding cat pack and instrumentaion</li>
<li> Using old Test Stand from 2011</li>
</ul>
<br />
To Do:<br />
<br />
<ul>
<li> Test Motor and refine design, iterate</li>
<li>Design and test high expansion ration version.</li>
</ul>
<div>
3)Good high quality vehicle simulation for performance optimization and HIL testing.</div>
<div>
Done:</div>
<div>
Selected Simulator (JBS Sim) and contracted to have a good initial model built.</div>
<div>
<br /></div>
<div>
In Process:</div>
<div>
Waiting initial model and simulation form person contracted to do the work</div>
<div>
<br /></div>
<div>
To Do:</div>
<div>
Optimize and evolve to full HIL simulator...</div>
<div>
<br /></div>
<div>
4)Build and Code Avionics:</div>
<div>
Done:</div>
<div>
Pick an archetecture (I think 75% confidence) we will use one of the tiny pixhawk clones for avionics.</div>
<div>
<br /></div>
<div>
In Process:</div>
<div>
Find a light weight GPS that will work without co-com limits at high acceleration.</div>
<div>
We have flown Piksi on a HPR twice continue to work on that aspect.</div>
<div>
<br /></div>
<div>
To Do:</div>
<div>
Design the full code set and test in HIL</div>
<div>
<br /></div>
<div>
</div>
<div>
5)Build and test GSE..</div>
<div>
Done:</div>
<div>
Conceptual GSE concept that minimizes weight on the airframe.</div>
<div>
Uses single "Tube" to fill and pressurize remotely.</div>
<div>
<br /></div>
<div>
InProcess:</div>
<div>
ToDo:</div>
<div>
Design airframe QD and ground GSE.</div>
<div>
Test Concepts via static tests...</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
6)Regulatory:</div>
<div>
Done Regulatory concept...</div>
<div>
<ul>
<li>Will do inital testing at FAR up to 50Kft.</li>
<li>Then will do suborbital flights offshore.</li>
<li>When time to go over 200K lb/sec or to orbit:</li>
<li> First stage constrained by physics from hitting anything.</li>
<li> 2,3,4th stages made of low temperature tolerant composites, so incapable of high speed flight in the atmosphere.</li>
</ul>
<div>
In Process:</div>
</div>
<div>
<br /></div>
<div>
To Do:</div>
<div>
Start discussion with FAA for orbital licensing requirements.</div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<div>
<br /></div>
<br />
<br />
<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com3tag:blogger.com,1999:blog-36913768.post-82307671261157115362015-11-14T21:17:00.001-08:002018-11-05T16:09:13.795-08:00Today's progress...Spent the first half of the day cleaning the shop.... I have way too much stuff.<br />
<br />
Then I machined the soft jaws of the three jaw chuck to grip the end of the 3D printed motors...<br />
<br />
Then machinedPaul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com2tag:blogger.com,1999:blog-36913768.post-44710223412684558892015-11-12T18:06:00.000-08:002015-11-13T15:31:10.638-08:00Jet Packs... aerodynamics questions and thoughts....If you follow such things the Jet pack from http://jetpackaviation.com/ was subject to all geek discussion last week. Today I say an article here:http://www.gizmag.com/jetpack-aviation-new-york-flight/40286/<br />
<br />
This describes the controls of the jet pack.....<br />
<br />
Notice that the only video we have seen is of it flying somewhat low over water. This means in the mind of the designer its not safe over anything hard. <br />
<br />
There is pitch and yaw control, but no roll control other than weight shift.<br />
To me this means that the output from the two jet engines must be really closely matched.<br />
Loose either engine to something as simple as an air bubble in a fuel line and your spinning wildly out of control.<br />
<br />
So how would you build a safe useful jet pack? <br />
<br />
Safe:<br />
Minor expected faults won't kill you.<br />
Single engine, sensor or actuator failures wont kill you.<br />
<br />
Useful:<br />
Able to fly at whatever altitude fuel will allow over any surface.<br />
<br />
<br />
In my mind a safe useful jetpack would have the following:<br />
<br />
Flyby wire artificial stability.<br />
Engine out failure recovery from any altitude.<br />
Safe escape from and single engine,sensor battery or actuator failure.<br />
<br />
This implies to me multiple engines with some kind of thrust vector control.<br />
You need enough control authority to maintain stability with one engine out.<br />
You need enough control authority to maintain stability with one actuator or motor in hard over failure.<br />
<br />
You don't have to always land, you can have failure induce a rapid climb to an altitude that ballistic parachute can deploy. (300 ft or so)<br />
<br />
<br />
Rather than two motors I would think at least two per side. This means that if you loose an engine on one side all of the the other engines must have enough control authority to keep thrusting through the center of mass. If the control authority point is above the CG (like their jetpack) then the gimbal on the good side will have to point toward the passengers legs, probably frying them. To me this imples that the jet point of thrust vector control must be below the CG. IE the jets must move down on the human. Then the thrust vector to compensate for rolling (or pitching) moment from a failure on the other side would point away from the pilot. It also implies that each side have enough thrust so that if 1 motor fails it can hold up its side......<br />
<br />
So I see something like 3, 4, or 5 smaller motors per side.<br />
<br />
With 5 motors a side I believe you might be able to control the vehicle with just thrust throttling...<br />
<br />
If you need thrust vectoring then a flap that you can deploy into the exhaust stream that deflects it in the direction of the semi circle away from the pilot. <br />
<br />
In thinking about things one of the scariest failures would be bearing failure where the motor dumps all its built up momentum in the free flying vehicle as its thrust goes away.....<br />
<br />
I just don't see how the Jetpackaviation jet pack we have all recently seen could be made "safe" for flight over hard surfaces.<br />
<br />
Some random observations:<br />
<br />
From their images JB-8 was more of a flying sled. Its real clear that the JB-8 used two TT-100 247lb thrust jets, the same as the sonix jet uses. These are about 50K each.<br />
(See <a href="http://www.pbsvb.com/customer-industries/aerospace/aircraft-engines/tj-100-turbojet-engine">http://www.pbsvb.com/customer-industries/aerospace/aircraft-engines/tj-100-turbojet-engine</a>)<br />
<br />
Its also clear that the JB-9 uses two smaller engines... AMT Nike motors.(24K Euro each) I wonder if the motors counter-rotate, or if they don't how much rolling moment pitch changes make given the gyro coupling.... since the designer and test pilot are both helicopter pilots they will be very familiar with the 90 gyro force motion phase shift....<br />
<div>
<br /></div>
In looking at the middle of their three videos the "Gopro" one that they are using standard box stock RC turbine ECU displays for the engines mounted on the stick grips, these displays are on the tether flight video, but not the NY harbor one... or the promotional jet pack pictures.<br />
<br />
On the tether flight video one can clearly see a large LIPO battery pack connected to the engine ECU under the cover.<br />
<br />
Also in the NY harbor video there looks like an added frame to keep the tether training cable from getting wound around the pilots head....<br />
<br />
Needless to say I want one...<br />
<br />
<br />
P.S. I want to see their blooper reel...<br />
Edited to add info on what motors they are using.<br />
<br />
<br />Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com15tag:blogger.com,1999:blog-36913768.post-3549747835477824592015-07-20T10:05:00.003-07:002015-07-20T10:51:26.533-07:00GPS on several fronts...This week end I flew an open source Piksi GPS on an HPR to see if it could be made to keep<br />
lock at high acceleration without any imu aiding. I modified the tracking constants of the piksi software .(actually used # defined for wide bandwidth tracking already in the latest software)<br />
<br />
It lost lock at boost, got lock again at apogee (strong winds at FAR apogee horizontal V was 204knots!) This pulled the electronics bay out of the vehicle when the drogue deployed at that speed. Fortunately its a sturdy rocket and it survived a no main chute deploy with minor damage.<br />
<br />
There were some issues I think I set the lock detection too too optimistic and it tracked some noise...<br />
I will fly a Piksi again recording the Raw RF some time in early Aug.<br />
(I'm also going to change out the TCXO for one with lower G sensitivity see discussion below)<br />
<br />
<br />
On a 2nd GPS front PSAS flew a software GPS receiver on their rocket on Sunday.<br />
They gathered raw data, but they don't have the full GPS solution working yet.<br />
They posted the following graph<br />
<div class="separator" style="clear: both; text-align: center;">
<a href="https://pbs.twimg.com/media/CKVcMBPW8AAp15g.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="240" src="https://pbs.twimg.com/media/CKVcMBPW8AAp15g.png" width="320" /></a></div>
<br />
It shows doppler shift in the tracked sats.<br />
I actually question that a little bit...<br />
<br />
Doppler is what makes a trains whistle change tone as if goes past.<br />
If you change the velocity with respect to a radio transmitter the frequency will shift.<br />
<br />
There is another effect that can also effect this data... the RF system on a GPS uses a very precise clock (usually a TXCO) in the receiver. That clock may have acceleration sensitivity.<br />
IE the frequency of this oscillator may vary with applied acceleration...<br />
<br />
I'm somewhat suspicious that the graph above shows this more than Doppler shift.<br />
I have not looked up the orbits of the gps sats at the time of flight or the position of PSAS flight, but I'll make some assumptions...<br />
<br />
The GPS sats are scattered randomly about, ie some are almost straight up and some are at the horizon. If the rocket flies straight up one would expect a bigger doppler shift for the sat straight over head and much less shift for the sats at the horizon as their relative velocity changes less.<br />
Also if the rocket turns into the wind and has some horizontal velocity one might even expect a doppler shift in the other direction for the sat you are flying toward/away from.<br />
<br />
However if the frequency shift is due to g effects on the reference clock one would expect all the doppler shifts to move the same direction....<br />
<br />
So it looks like they got a shift of about 1400 hz at 1.5Ghz that would be a velocity of 140 m/sec or so... at 1.5 Ghz. So the magnitude is withing the realm of possibility...<br />
<br />
(The graph also shows an overshoot at the end of the rocket burn this is the acceleration changing direction from the perspective of the GPS receiver.)<br />
<div>
<br /></div>
There are vendors that specifically sell clock oscillators with low G sensitivity...<br />
(http://www.vectron.com/products/g_sensitivity/gsensitivity_index.htm)<br />
<br />
Given their data the PSAS should be able to determine this.<br />
With a full GPS solution derived from the data (they have not done this yet)<br />
They will get position velocity and time....<br />
They also have sample of data precisely clocked out via their reference oscillator...<br />
The difference between the time in the solution and the time via their local clock can<br />
be measured and will give an idea of clock drift.<br />
<br />
They can also calculate the expected doppler between them and the individual sats and see how that compares with the measured doppler any difference is clock error...<br />
<br />
All of these data extractions require they get a full solution running....<br />
<br />
There is a quick and dirty test they can do with just what they have...<br />
<br />
Run their gps sampler system on the ground with a fixed stationary antenna...<br />
<br />
Now take the GPS board and orient it it differently in the 1g gravity field.<br />
6 combinations IE board component side up, component side down, tipped on its end, pointing up, down right left....<br />
<br />
and generate the doppler graph above... if the doppler shifts with orientation of the sampler board then they probably need a more stable clock.<br />
<br />
At bare minimum this test will show them what axis has the lowest clock sensitivity....<br />
<br />
In any case I really applaud what the PSAS guys are doing!Paul Breedhttp://www.blogger.com/profile/11024641086551653462noreply@blogger.com11