Wednesday, December 29, 2010

PET third stage COTS tank





Betterbottle makes 5 and 6 gal PET water bottles. I could only find a source for the 5 Gal, so that is what I tested.

Empty 674 gm
MR with water of 29 with peroxide 39!
Burst at 125 PSI.
Long period of plastic deformation at around 100 psi
It burst in the thin center with the ends remaining substantially thicker.
This means one could probably prevent the banana deformation and increase the pressure with a center overwrap.

Tuesday, December 21, 2010

Way out of the box presure system...

Another out there concept... this won't work with the muiulti segment tank of the last wild idea, but will work for a single tank.

In a H2O2 rocket 80% of the propellant volume is H2O2, so you need to pay more attention to the H2O2 side than the fuel side.

Leave a small space at the top of the H2O2 tank. In this space put a solid silver screen/catalyst hung from a thermally compatible string. Unwind the string into the tank letting the silver decompose the H2O2 pressurizing the tank, raise and lower the catalyst to control pressure.

Fuel is pressurized with a bladder from the gas in the main oxidizer tank.

Main propellant valve is a simple burst disk.

Monday, December 20, 2010

Way out of the box...

A 3rd stage made of 3L soda bottles surrounding a 3U Cube sat.
3L soda bottles are good to 100PSI with a Mass ratio of > 40 when used with H2O2.

The "goodness" of normal rocket tanks are usually rated by the PV/mass. The best aerospace composite tanks, like the Scorpius pressurization tanks used by Armadillo in the 180sec super mod can have mass ratios of better than 9 at 2200 PSI working pressure. If you could scale this to a 200 PSI tank then you get a water filled tank mass ratio of >80. The fundamental problem is for the small sizes we are talking about you can never get that low. The tank wall would be paper thin. At small sizes the issues are minimum gage not minimum strength. (Hard to beat a soda bottle 0.25mm thick. )

As soon as you go up in size bigger than minimalist nano sat launcher then properly built aerospace quality tanks are a must.

I also suspect that when fighting minimum gage issues going up in pressure for a tiny launcher can have benefits in motors size, expansion ratio, flow path sizes etc....
A big puzzle with too many knobs.

Here is a link to the specs for high quality aerospace tanks...

Wednesday, December 15, 2010

A salute to the Military etc...

For my U.S. followers remember the Americans that voluntarily offer to pay the ultimate price in defense of this nation. Reguardless of how you view the current conflicts, you can not help but be humbled by the voluntary sacrifce these men and women give in our name.

Give them something, I contribute every year to

Sunday, December 12, 2010

List of significant parts....

In trying to determine the scope of a Nano sat launcher project I generated the following list or physical hardware. There is an equivalent scope of work for Ground support, Software, Logistics, Regulatory issues etc...

  1. Nose cone/aero shell
    1. Aero shell separation system
  2. Nano sat mount
    1. Nano Sat ejection system.

  1. Avionics:
    1. GPS/ MEMS IMU Integrated system
    2. Avionics control
    3. Telemetry system
    4. Battery System

  1. Third Stage
    1. Tanks (assuming tanks are the structure)
    2. Valves and Actuators
    3. Pressurization System
    4. Motor
    5. Motor Thrust transfer structure
    6. TVC Actuators.
    7. Separation mechanism
    8. Fill and Drain Umbilical system.
    9. Roll Control TVC

  1. Second Stage
    1. Third Stage Support Structure
    2. Battery for second stage actuators.
    3. Tanks (assuming tanks are the structure)
    4. Valves and Actuators
    5. Pressurization System
    6. TVC Actuators.
    7. Motor
    8. Motor Thrust transfer structure
    9. Separation mechanism
    10. Fill and Drain Umbilical system.

  1. First Stage
    1. 2nd Stage Support Structure
    2. Battery for first stage actuators.
    3. Tanks (assuming tanks are the structure)
    4. Valves and Actuators
    5. Pressurization System
    6. TVC Actuators.
    7. Motor
    8. Motor Thrust transfer structure
    9. Fill and Drain Umbilical system.
    10. Launch Hold down mechanism

Wednesday, December 08, 2010


Congratulations to spacex.
The scope and scale of what Elon and his troops have accomplished is just breathtaking.
I am in stunned awe.

I raise a toast to a most unreasonable man!

Sunday, December 05, 2010

Testing results... sort of...

We went out to FAR setup the teststand, and the little stainless motor.
The temperature was really cold (45 F) and the cat pack never warmed up. By the time it would have been warm, it was dead, due to contaminated peroxide.

I disassembled the cat pack and dropped the screens in the peroxide dregs from the Jug we loaded from and there was almost no activity.

I then got a jug from a different batch and tried that, no activity.

So I cleaned the screens in 68% nitric acid. I then tried them in both batches of peroxide. Batch #1 killed the screen almost instantly.Batch #2 was reactive, so I let a screen soak in batch #2 after 2 or three minutes the screen was no longer reactive. The only conclusion is that both batches of peroxide were contaminated, batch #2 less so.

As a Final test I took a fresh clean screen and the screen that sat in batch 2 and put both in my beaker of peroxide, there was a big difference in reactivity, something is definitely contaminated. My Peroxide supplier thinks it was phosphate and has redone his proces to remove phosphate.

The end result is that engine tests will have to wait till I can get new peroxide or get my spargeing plant up and running and make my own propellant. The current tall pole in that process is diesel generator problems/waiting for parts.

In the mean time I'm going to work on tank development and some guidance and control electronics.

Tuesday, November 16, 2010

Some thoughts on an orbital launcher.
  • All stages contribute the same DV (Bad assumption)
  • 9500 M/Sec Delta V may not be enough for a really small vehicle.
  • MR is achieved MR per stage including payload.
  • We assume the MR is the same for each stage (again a bad assumption)
This table shows you the minimum ISP performance you need given an achieved MR and a number of stages. For Reference the Blue Ball with no payload and no legs had a MR of between 5 and 6. If my notes are correct the Falcon 1 first stage with no Payload and no 2nd stage has a MR of about 16.

MR is down the left side, number of stages is across the top.

Minimum ISP
Stages 4 3 2 1

2 349.3 465.7 698.6 1397.1
3 220.4 293.8 440.7 881.5
4 174.6 232.9 349.3 698.6
5 150.4 200.6 300.9 601.7
6 135.1 180.2 270.2 540.5
7 124.4 165.9 248.8 497.7
8 116.4 155.2 232.9 465.7
9 110.2 146.9 220.4 440.7
10 105.1 140.2 210.3 420.6
11 101.0 134.6 201.9 403.9
12 97.4 129.9 194.9 389.7
13 94.4 125.9 188.8 377.6
14 91.7 122.3 183.5 366.9
15 89.4 119.2 178.8 357.6
16 87.3 116.4 174.6 349.3
17 85.5 113.9 170.9 341.8
18 83.8 111.7 167.5 335.0
19 82.2 109.6 164.4 328.9
20 80.8 107.8 161.6 323.3
40 65.6 87.5 131.3 262.5

The second chart shows the vehicle gross lift off weight given a 1Kg payload and assuming that the empty stages weigh the same as the payload they are lifting.

GLOW multiplier

4 3 2 1

2 256 64 16 4
3 1,296 216 36 6
4 4,096 512 64 8
5 10,000 1,000 100 10
6 20,736 1,728 144 12
7 38,416 2,744 196 14
8 65,536 4,096 256 16
9 104,976 5,832 324 18
10 160,000 8,000 400 20
11 234,256 10,648 484 22
12 331,776 13,824 576 24
13 456,976 17,576 676 26
14 614,656 21,952 784 28
15 810,000 27,000 900 30
16 1,048,576 32,768 1,024 32
17 1,336,336 39,304 1,156 34
18 1,679,616 46,656 1,296 36
19 2,085,136 54,872 1,444 38
20 2,560,000 64,000 1,600 40
40 40,960,000 512,000 6,400 80

The two bold numbers are about where I think my notional vehicle will land on this chart. This was a 1Kg nanosat with 1Kg of support structure would have a gross liftoff mass of ~2200 lbs, and the engine performance is a relatively easy ISP of 232 (Easy in vacuume, a bit harder on the first stage) Total Vehicle empty wt would be between 500 and 600 lbs.

you can do some really gross things... like a monoprop 4 stage launcher... MR 6 Glow for 1Kg payload is 40000 lbs.

Monday, November 15, 2010

My weekend ......Frustrating

We went out to FAR and set up the test stand.
Everything checked out we put in the fuel (gasoline) and
were preparing to load peroxide. When we opened the cap
there was a black substance stuck to the cap, when we open more fittings
there was an unknown black substance. The tank had been a peroxide tank.
It sat in the garage sealed for 2 years. On Friday we hydroed the tank and say no sign of contamination. The rough drive out to FAR dislodged some kind of black/brown powder from the inside of the tank. The powered looks like Iron rust on close inspection and is very reactive with peroxide. So the test was scrapped. It makes me wonder if something is leaching out of the aluminum after being stored for a long period.

We need to add interior visual inspection to the check list for all stored tanks, even if properly sealed and stored.

We worked on the big generator, burning the stale diesel and replacing with fresh. (Still not running)

On the plus side we did get our primary storage container cleaned up.
(As a result the garage at home is in distress once again)

We tested some of the super chemical compatible K190 resin for peroxide compatibility. It responded almost identically to the easier to get Vipel F010. A slight etching of the surface.

We'll see if we can fabricate a new test stand tank this week, and try again next weekend.

Friday, November 12, 2010

My Weekend....

I just finished hydroing the test stand and setting the pressure relief valve.
I have to hook up two pressure transducers to the electronics and the Stainless motor is ready to test. We will probably go out to FAR sometime Saturday and test the motor, work on our generator, and clean out our container. The clean out the container part probably means we will be out there overnight Saturday night and return some time Sunday.

Wednesday, November 10, 2010

Ways to save the world... and more Rockets

Saving the World
Any long time blog reader reader has already heard my rant about the only way to really spread an American standard of living to the entire population of the world requires that we find new resources, not just recycle our soda cans. I believe that off planet resources will be a significant part of the solution for things like rare earth metals, platinum group metals, expanding humans into the solar system etc.... The other half of this is a cost effective green energy source. I'm still very skeptical about the ability of space based solar power to solve the energy issues here on earth. I think its much more likely that small modular fisssion reactors and hopefully fusion will solve the energy problems.

A few weeks ago I posted about LPP. since that time I have visited their facility. I went through the lab and got to watch several "fusion" shots. They have multiple different ways to detect neutrons and are clearly generating neutrons via D-D fusion. They have obviously spent a fair bit in building their lab, but none of it was wasted in any way. They have good instrumentation and a well setup shielded room, but the rest of the lab space itself could be generously described as spartan. Its obvious that the people working on the project are passionate about what they are doing and believe they have a pretty good shot at making it all work. As a result I've decided to personally invest some $ in their business. If you are an accredited investor give them a call.

Back to Rockets....
I've started in earnest to work on a plan for winning the Nano Sat contest. There was a big meeting to kickoff the contest last week and in my mind the only significant questions left about the contest will be
  • How do they resolve the no government funding rule,
  • Who will be the allied organization.
The overall goal of centennial challenges is to encourage innovation from individuals and companies that are not part of the traditional aerospace environment. The goal of the specific Nanosat prize is to try and kick start a low cost nanosat launcher. At some level the two goals are in conflict. There are many small SBIR sized companies that have received government funding to work in this area, and so excluding government contractors from the contest will limit the pool of people that might succeed, at the same time including people receiving significant government funding really violates the spirit of the centennial challenges.
Personally I would like to see the same no government $ rules that were part of every previous centennial challenge.

On the technical and regulatory side of the house many many questions remain.

This weekend I hope to finally fire my stainless printed motor.
Building more real hardware really requires that I get more details of my notional launcher nailed down.

Friday, November 05, 2010

A personal non rocket tale and warning.

This has NOTHING to do with rockets but I think its important.
For the last two plus years I've felt tired and somewhat depressed.
I just thought I was getting older and though it was normal to feel drained all the time.
Last year while I was driving toward the LLC I was not getting a lot of sleep, largely by choice.

After the LLC I was looking forward to getting my energy back but no matter how much sleep I got, I woke up feeling trashed. I could barely work past 9pm without becoming dangerous and/or unproductive.

A month or so ago My wife went up to Long Beach for 4 days.
On Sunday I slept by myself and Monday I felt terrible. On Monday I drove up to Long Beach and spent the night with her, Tuesday I felt fine. Tuesday night I was home alone and Wednesday I felt terrible. Wednesday night she came home and Thursday I was ok.
I pointed this out to her and she said "when you roll over on your back you snore and I elbow you to make you roll over."

A light goes on My 80 yr old father has Sleep Apnea so I call my Dr and explain the A-B-A-B experiment I had just done. He says he will schedule me for a home sleep study..... 10 days later its tied up in the insurance authorization never never land so I buy myself a recording pulse oximeter and record a nights sleep. I find that my O2 sat goes to less than 80% more than 20 times in a 6 hour recording.

Armed with my data I say dam the insurance and full speed ahead. So I go in and see a sleep doctor that schedules a formal sleep study. The result is that I was having 33+ apneas an hour,
and not just while I was on my back.

When this happens your body senses that something is wrong and sets off all the panic alarms and wakes you up. As a result anytime I got into REM sleep it was short lived and unproductive.
You also get to activate your fight or flight alarm hormones every night. It also explains why I would wake up a 3 am feeling exhausted yet unable to go back to sleep. My body was in panic alarm mode. I was inadvertently running the REM sleep deprivation experiment.

I got a CPAP machine on Wednesday this week. Its only been two days, but I feel 1000% better. I wake up feeling rested, I worked late in the shop last night and got a lot done.

I'm writing this so anyone that snores and is feeling tired will seriously consider getting a sleep study. I did not look forward to sleeping with the Mask and hose etc.. but the change in how

I feel has been so dramatic that I would do it in an instant even if it meant wearing the mask 24/7. So if any of you are feeling tired and run down, not yourself depressed think about a sleep study.

I realize that something once written is on the Internet forever and that this revelation
might cause me some grief in the future while looking for jobs, contracts etc.... but if just one person reads this and it prods them to get checked out it will be well worth it.

As a side note I hope this will mean a lot more progress on the rocket projects!

Monday, October 18, 2010

Weekend update...

The stainless motor and test stand are almost ready to test.
Waiting for some more silver screen to arrive so I can make small cat packs rather than wastefully cut up 6" packs.

I worked on putting some more storage and shelving into the garage.
(My son finally gave up on the fantasy that one might someday park a car in there)

Sunday I went out to FAR and worked on getting generator set up for Propellant processing facility. I've never had a gas motor beat me, alas the universe is telling be I'm not a diesel mechanic. Will try again next time on site.

I will be at the conference on the 29th 30,31st so if your there say hi.

As a science geek I enjoyed the 4 part videos from LPP power they are trying to do fusion on a shoestring and are being very open about the process. A long shot but if something like this works it changes the world..... Part 1

Sunday, October 10, 2010

Composite Compatability tests.

I soaked 8 composite samples in 85% peroxide for about 5 hours at 70F.
Top Row:
  • Epoxy with no fiber
  • Glass fiber in epoxy
  • Kevlar in Epoxy
  • Carbon in Epoxy
Bottom Row: Vipel 010 Chemically resistant vinyl ester
  • Vipel Resin no fiber
  • Glass fiber with vipel
  • Kevlar with Vipel
  • Carbon Fiber with Vipel.
Experimental setup.
I set out 6 polyethylene cups with 300ml of 85% H2O2.
I tied polyester cord to each sample and placed them in the H2O2 solution.
They were placed so 75% of the sample was covered.
The Pure resin and glass fiber samples with the same resin shared a cup.
I put a clear polyethylene bag over each cup.
I periodically observed the samples.
I left them in the sun for ~5 hours.

The bags of 4 of the sample cups were clear, the bags over the two carbon fiber samples has fogged condensation on the inside of the bag. This seems to indicate some H2O2 decomposition.
It was not enough to measure any significant volume change.
None of the samples had shown any significant h2o2 decomposition. They were filled to 300ml +/-10ml and at the end they were all 300ml +/- 10ml.

I then removed the bags off the top of each cup with a long set of tongs.

After the 5 hours I was hesitant to handle the sample or move the containers as I was possible I'd created a hazardous solution. So I could not weight the samples.

After 5 hours the epoxy samples all had a layer of something floating on the top of the H2O2.
The Vipel samples had no visible contamination of the h2O2.

Then one by one for each sample (except the pure resins)
  • I grabbed the loose cord tied to each sample with the tongs, carried them over the the wire fence and hung them on the fence.
  • I then shot the sample with a 243 winchester with 85gr bullets from about 25 ft away. The impact velocity was 900 to 1000 m/sec.
None of the samples showed any sign of detonation or any increase in energy release from the rifle shot. I did not shoot the pure resin as I expected the pure resin would shatter and not provide any additional information.

After determining that none of the samples detonated I then individually dumped each h2O2 container on the dirt. (Mojave dirt is a great decomposition catalyst.) No notable difference in energy or release was noted.

I then removed each sample from the fence and soaked them in water to remove the peroxide.
The samples are shown in the picture above. The Vipel samples showed some surface etching, ie they had an oxide layer on the surface, but showed no significant structural degradation.
The epoxy samples wer reduced to bare fiber. There was almost no structure left.

In the picture both bare resins look discolored, but the Epoxy is bubbled and distored, where the layer on the vipel is just a surface layer its very thin. It almost looks like the oxide layer aluminum gets after a lot of peroxide exposure.

The company that makes the vipel F010 has an even more resistant resin, K190 that is harder to get. The K190 is rated for 50% peroxide at 100F for years of service.
Their chemical compatibility guide

When I'd finished pouring out the peroxide in the 6 cups I had a 100 ml or so left in my transfer cup. So I put a bunch of raw kevlar with no resin in that cup. It had ZERO reaction of any kind, no bubbles, no discoloration, no steam on the bag etc...

Tuesday, October 05, 2010

First test part in the bag

My first tank part attempt is in the vacuum bag and should be curing. Its been 90 minutes since I mixed the resin and its still fluid and not getting warm yet....I hope I converted drops of hardner to grams correctly for the resin mix.

It is a cold evening could just be slow

Having resin that does not go off makes a nightmare.
In any case I doubt the first attempt will be pretty....

Update the resin in the mixing cup got hard, I peeled the vacuum bag blotter felt and peelply and the underlying composite is still tacky. (Its really cold and damp in San Diego today so I'll let it sit another 24hrs.)

Monday, October 04, 2010

Tanks the other hard part

The Rocket Equation has a term that is the rocket motor efficiency and a term that is the mass ratio. In a pressure fed system the biggest component of that mass ratio is the tank.
If I could make a tank identical to a 2L soda bottle only 5 to 10 times bigger that would be almost ideal. I could probably find a mechanism, to join a bunch 2L soda bottles and I may pursue that, but I'm also going to try my hand at composite tanks. Toward that end I made mold forms for a 6" diameter cylindrical test tank mold. I heated it up and waxed it with mold release and setup the vacuum bag etc.. got ready for my first composite test part.

I have something non-rocket to do tonight, but tomorrow I hope to try making my first composite part since the solar plane project.

The first tanks will have glued Mylar liners that are not H2O2 safe, but the flight tanks will have mylar/PET liners with no glue. The jury is still out if the tanks will be seamed via vacuum heat, sonic welding, or RF welding.In addition to the liner I also want the tank to be chemically resistant to the H2O2. I want any liner failures to not be immediately catastrophic.

I'm getting a bunch of samples and setting up to do compatibility testing next weekend out at FAR. I'm testing glass, kevlar and carbon fibers with normal epoxy, vinyl ester and special chemically resistant vinyl ester resins. My gut says that plain E glass with the chem compatible resin will be fine, I'm almost certain that carbon with epoxy won't be. I hope the Kevlar and chem resistant resin also work as the kevlar is a bunch stronger than the glass.

Its a multi part test, start with 30% and work your way up to heated 85 or 90%. Anything past 50% really has to be done remotely. I'm planning to soak samples in PET soda bottle bottoms. sitting in hot water on a hot plate. The sample will have a string and pulley so I can pull the sample out of the solution remotely and shoot it with the 243. I could set up some kind of hammer and anvil test, but I worry that if it goes bang, the hammer becomes a projectile.

I figure I'll get the preliminary screening done this weekend and the samples that pass will get the hotplate test in two weeks.

Tuesday, September 28, 2010

A few ideas and loose ends

This week I learned that the NASA Nanosat prize is funded, (I thought it was a proposal not a funded prize.) So this clearly puts a bulls eye on a project target. This process starts with a notional vehicle and works backwards from the last stage. With a 1Kg payload I think that I can build a three stage launcher with a gross liftoff mass of less than 1000lbs.
To do something on this scale every gram matters. I'm starting to designbthe best 3rd stage I can and works backwards... (If you do a good enough job you only need two stages)

One needs:
Efficent light high expansion motor. Working on small motors via the DMLS project.

Really light tanks.....I've purchased all the large beverage containers I can find and am weighing and pressure testing them. So far the best tank is a 2l soda bottle. 100+PSI and mass ratio of > 40. A single soda bottle is not really enough. Any scheme to group them together is heavier than the bottle. So I'm looking at maybe fabricating my own tanks. The idea H2O2 tank would be mylar lined (mylar is another version of PET like in soda bottles) with chemically compatible resins and kevlar. Normal Epoxy and normal Carbon fiber are not happy with H2O2. All the tanks at this scale are up against minimum gage issues so whatever pressure you get in the tank will be more than really needed. In concept these seem very similar to the H2O2 tanks shown by Richard Speck of Micro-space at the 2007 LLC. I've got most of the materials to try this on the way. The biggest unknown issue is how to build the liner. If I can make the process in patent #3661675work that would be ideal.

Really light valves and actuators... probably all based on brushless model airplane servos. one can get lighter brushed parts, but must trade against the requirement to put them in a pressure box and the smallest brushless ones seem to be a win.

Guidance.... more on that later...

Regulation... This one is hard because the regulatory framework that applies to orbital launches is tailored toward something like a big Atlas. My current concept is to make the 2nd and 3rd stages really light and fluffy. Almost all plastic, including the valves and plumbing. Only the thrust chamber will be non-plastic. The first stage will probably be metal. The concept is to launch off shore so that thrid party safety from the first stage is constrained by physics and the 2nd and 3rd stages are too light to survive reentry. The real trick will be proving that and path taken by the 2nd stage will either burn up or land within the 1st stage constrained by physics zone. IE if it shoots straight back down its not going so fast so it might burn up. If it flies perfectly by the end of its burn then its going to fast to survive reentry. The question is what happens between these two zones. My nominal vehicle meets all of the amateur limits except the no orbit allowed rule. IE less than 200Klb/sec and orbital altitude less than 150km. (Rules say you only need to go around once.) more rambling to follow as I figure things out.

Anyone in SoCal with access to a 14" diameter 20" long vacuum oven that I could use to try the process described in the patent above would be really helpful.

Wednesday, September 22, 2010

More Printed Motor news...

The DMLS machine that is most common is an EOS270. The company that makes these machines has recently started adding some new materials. The new Material I'm most interested is Aluminum for chambers, and maybe Inconel 718 for a possible turbo pump.

I'd gotten some chamber quotes a year or so ago and it was still too expensive. When I had GPI quote my design again this year it was half of what last years quote was and I ordered the part on the spot. (In Stainless) GPI was also very helpful in making geometry suggestions that woul d improve the quality of the resultant part.

After placing this order I thought I'd do some more price research and sent the same file to Morris Tech to quote. The response from Morris was very competitive and its clear that this industry is seeing significant price declines. (Neither vendor knows what the other quoted) I hope its a sustainable trend and not a bloody battle to bankruptcy.

I really don't like beating vendors against each other because any long term relationship needs to be win-win and you can't do that by abusing your vendors. While it might be tempting to beat vendors prices against each other, its not some thing I do.

I also asked both Morris and GPI about the availability of Aluminum.
GPI indicated that they would soon be running Aluminum and Morris indicated that they had already run some Aluminum parts and that in the next few weeks they would be running some more aluminum test parts.

Since I was doing interesting stuff as an individual inventor not a big corporation Morris offered me the chance to add a single part to the Aluminum test run for approximately their direct cost. Its an offer I can't refuse. So I will soon have small DMLS chambers in two materials!

The Aluminum Motor is actually a bit bigger than the stainless motor as it needs to be cooled the whole length with a stainless cat pack support thermally isolated from the cooled aluminum chamber as a sleeve inside.

So if you need DMLS parts there are at least two really awesome DMLS vendors in the U.S.

Saturday, September 18, 2010

Why the motor has horns.

If you look at this post from July. You will see how the finished motor will look. Rather then spend lots of $$ making the simple upper section I only had the lower part printed with DMLS. The upper section where the cat pack will go is fabricated in the normal way from a sanitary fitting. It will and then be welded to the motor bottom.

The horns sticking out the side are the fuel feed. The fuel goes in the curved part and a 8-32 Set screw with a orifice drilled in it goes down the straight section. Then the end of the straight section gets plugged. You can buy predrilled orfices in 8-32 set screws from Mcmaster Car.

Here is a picture of all the bits before welding:

The two small parts are the machined elbows to connect the vertical feed tubes with the Chamber top.

Wednesday, September 15, 2010

Sunday, September 12, 2010

Pressure Fed Upper Stage.

I've been doing some calculations on what an upper stage for the 1Kg Nanosat launcher would look like. One of the interesting twists is that if the motor only has to run in vacuum then it's ISP is almost independent of chamber pressure. So for any small launcher you are going to have minimum gauge problems long before you hit the minimum optimum tank wall thickness. This opens the possibility for tanks with things like 3L soda bottles and PVC valves. It makes me wonder why Space X went with the turbo pump 2nd stage for the F9. a lot of complexity for very little gain? Maybe just because they had one that was approximately the right size.

Wednesday, September 08, 2010

Some progress...

This weekend I worked on cleaning up my Garage.
I cleared the floor, two junk Tables and a cart. Everything I cleaned up now has a place. I still have piles on one bench and one cabinet. When those are done I need to start the task of going through all the storage containers, drawers etc.. and purge stuff I'm never going to use. A little bit more room would be really helpful. All in all I feel a lot better about the garage after putting three full days into it.

My Son and some of his friends went to burning man so just as I start to get a handle on the garage the truck comes back from Burning man filling the garage with dust covered stuff..... they have been working evenings getting it cleaned up so I can't really complain.

I tried to fill the porosity of my printed motor with some solder and I just could not get good penetration. It didn't stick to the stainless even using some fairly aggressive acid flux. As a result I redid my printed motor design for the DMLS process and had it quoted by GPI prototype. Their price was about 4X the Shapeways price, but the part is thinner and needs a lot less welding. (Its also about 2/3 of what I though it would be.) I ordered it Tuesday, so we should get it some time in the next two weeks. The parts on the DMLS "showcase" always look incredible. I asked them to give me the best possible price so please give it to be raw off the machine. It will be interesting to see the raw finish.

Sunday, September 05, 2010

An Orbital Vehicle Part 1

What does it take to build an orbital vehicle?
My interest is in something really small say a nano sat launcher. This is going to require more performance than a larger rocket as air drag has so much more effect. I'll start with John Whiteheads paper. For a LOX Hydrocarbon stage to get to a 200Km orbit he says we need ~9500 m/sec Delta V and for a 1T vehicle. This paper claims this was a simple analysis, and I always like to cross check. From the Falcon 1 Users guide table 2-1 we get the following:

2nd stage:

1200lb empty

8900 lb propellant

400kg (880lb) payload

317s ISP

Using the rocket equation I get 5173 m/sec DV

1st stage:

3000 lb empty

47380 propellant

10980 lb Payload(The 2nd stage)

300 s ISP

Using the rocket equation I get 4353 m/sec DV

Total DV 9526 m/sec

Extrapolating in the "How Small" paper we get about 9250 for a Falcon 1 sized vehicle. So I have a source to give me some target numbers and have independently verified that the numbers are not wildly off. So we need to design a vehicle with 9700 m/sec of Dv to go orbital.

The 180 sec LLC vehicles needed 1765m/sec DV. So orbit is a whole bunch harder. We could use the LLC L1 level of technology and stage 5 times this would weight 750K lbs. Clearly we need to do better. All but the first state will run in vacuum, they don't need to throttle, we don't need landing gear, so we should be able to do a lot better. My initial spread sheet says its quite possible with a three stage H2O2/Hydrocarbon vehicle. To do it in 2 stages would require developing a lightweight pump or making the vehicle really big. I'm going to refine my inital guess and publish it in the next week or so.

Wednesday, September 01, 2010

Keeping a neat Shop...

My review at my first ever "real" engineering job said something like:

"Paul Moves his assigned projects directly to the desired result with exceptional speed and skill leaving a trail of destruction in his wake."

This was a job where we built real prototype hardware controlled by electronics and
some of the earliest embedded computers. (6502 anyone?). I got the Job done but I left a wake of debris behind. Not much has changed. My rocket shop occupies a two car garage and a 8x10' office at my home. I find the continuous mess and inability to find things is probably the biggest frustration in my life.

I intellectually realize that I'm whining about my own personal shortcomings and should just gut it out and clean up my space. In my life I've never achieved that for any period of time measured in units longer than an hour. So I'm asking my readers if anyone has successfully overcome the this particular demon? I'm open to suggestions?

Its really a two part problem

Part One I have way to much stuff crammed in too small a space. So it needs a Major organizational redo. ( I can actually envision someday solving this part of the problem.)

Part Two once everything is organized how does one maintain cleaned up?
The Failure Scenario goes something like: Come home from work, family is going to have dinner in an hour so I go out to garage and start machining a pressure test plug, then dinner is called and I go in and eat... not to return to that project for a few days. This is complicated by the fact that I often have half a dozen partially finished projects in work at one time and I work on the different projects as I'm inspired to do so. This is not a complete failure as I actually do finish a significant percentage of what I start. (It may take 12 calendar months on a project that is only one real week of work)

Some specific questions for comment:

How do you handle partially finished projects in a way that you can efficiently task switch without leaving piles of half done all over the shop?

How do you decide when to throw something out?
Our current rule is if it is not a tool and has not been touched in (Replacement Cost /25) months it goes in the trash. If the value is over $250 it goes in the ebay pile... (The Ebay pile may someday actually make its way onto ebay)

How often do you redo your storage systems.....
How much dynamic range to you leave for expansion?
IE I have a drawer for AN male elbows. When I create the drawer its 25% full, a year later its over full and won't close so it sits on top the pile....

Has anyone ever tried to hire someone to clean up/ maintain their shop?
How did that work? How did you find such a person?
In So Cal one can find lots of low skill labor that will follow directions, but I think I really need someone that knows the difference between a drill bit and a mill bit, a servo and a valve etc...

Do you think it would be possible to hire a Science/Tech interested high school student to work on this without leaving them emotionally scared for life?

Tuesday, August 31, 2010

Getting back to rockets.

I've been working on several different projects. My printed motor looks finished, but when I pressure test it leaks EVERYWHERE so I can try to fill the pores with tin and silver solder being careful not to clog cooling passages or get silver where it shouldn't be, (Silver is catalytic with H2O2) or I can see if I can afford having the part made by the better DMLS process. I just sent out a modified 3D model to have that quoted.

I have my custom GPS front end digitizer done and most of the FPGA work done for fast correlation hardware , but I have not put all the parts together and applied power. I hope to get to that in the next month or so.

I also have a few small electronic projects I committed to do for FAR infrastructure so I need to spend some time on that this month as well.

The potential NASA nanosat launcher prize may change my path, but I'm still thinking the year or so out goal is a reusable vehicle that can go to 100Km and back. It will be much smaller than the Masten and or Armadillo plans. It will also look more rocket like.

Four years ago I bought an 02 Dodge Ram 1500 Crew Cab to drive back and forth to the desert in a reliable comfortable truck. I've since put an additional 110K miles on it and two weeks ago Sunday it tried to kill me by blowing out the rear end and locking up the rear wheels. I spun it pretty hard, got it on two wheels, but did not flip it or hit any thing. I knew I eventually had to replace the truck, I'd just spend 1K getting the truck all ready for the fall rocket season,
new brakes, AC system cleaned up etc...

I have a general rule that I don't let a vehicle strand me more that twice. The dodge already left me stranded about a year ago with a blown water pump, this was its second misdeed. So I went out and bought a year old 09 Super Crew F150 It has 17K miles on it and I got a good deal. This sets the rocket budget back a little bit, but business seems to be recovering and it should not be a big issue much beyond the first of the year.

I'm actually getting excited about working on rockets again and hope to get back to regular progress in the next month or so.

Tuesday, July 13, 2010

NanoSat Centennial Challenge

The cost of getting to orbit is the real barrier to space exploration, settlement, and harnessing of off earth resources. The difficulty of the problem makes it hard for small innovative organizations to have a shot at making a launcher for commercially interesting payloads. Doing a nanosat launcher is not as difficult. The New NanoSat contest looks very good. If I had the resources to offer a significant prize it would look very similar to the NanoSat prize. I'd add some bells and whistles like a bonus for a reusable vehicle and a junior league 100gm category, but all in all it looks almost perfect.

Monday, July 05, 2010

More printed Motor Progress

The printed Motor parts are all here, I have a few things to finish and it will be ready to run.
I made the tubes for the fuel input too short and connecting to them is going to take some creativity. The end cap with o-ring grove, clearance for flow and fingers to push down on the cat pack turned out well:
I've sent out the order to get the catalyst retainers water jet cut.
All the bits and pieces should be here by mid month. If I will decide to brave FAR/Mojave in peak summer is a different question. There is a real possibility it won't get tested till mid to late September. Business continues to go reasonably well, this means that I should be able to ramp up my rocketry projects after the first of the year.

Monday, June 07, 2010

Parts Came in...

The sheet of paper the parts are laying on is 8.5x11"
My Welder Sent me this Picture . He still needs to weld the bottom manifold on,
When I ordered this version I did not order the bottom manifold because I had one. alas I was showing the previous version to people and either I left it at FAR, or someone walked off with it.
I've ordered another bottom manifold ring it will be two weeks or so.

Sunday, June 06, 2010

Some Data

I've now flown the simple instrumented HPR 5 times with data recording.
I've learned some things

Flight 1 at FAR Spark fun IMU, GPS and 6DOF Analog devices ADIS16360
GPS did not work at all, Spark fun was noisy, ADIS16360 worked reasonable well

Flight 2 At FAR, shorted battery cable, only goy Spark Fun IMU data.

Flight 3 at Plaster City (Yesterday) OpenPilot 10Hz GPS and ADIS16400 Analog deivces IMU.
GPS lost lock moments abter ignition (10 G or So) ADIS data all looks good.
On board recorder did not work, only have down link telemetry.

Flight 4 at Plaster City (Yesterday) OpenPilot GPS and ADIS16400 Analog deivces IMU.
GPS kept lock till parachute deployment (where the GPS is now pointing at ground).
Take off was only about 6-7G, while the GPS says it kept lock, the altitude data was wrong and did not follow the flight path, onboard data recording worked correctly. (A few minor drop outs, I think the data recording connector is intermittent)
Flight 5 At plaster City Same setup 10-12G launch, GPS lost lock, ADIS16400 data looks good.
Telemetry log only, on-board recorder did not work.

Things I've learned:
  • The $125 Spark Fun 9DOF IMU does not like rocket vibration, and the accelerometer saturates on the rocket.
  • The $500 ADIS16400 is really pretty good, the data is clean and seems to make sense.
  • The low cost 10Hz GPS's are not happy with high acceleration. (To be expected)
  • The Max stream 900Mhz Xbee seems to be reliable even with grossly sub optimal antennas.

My goal is to develop a low cost system, buying a 5K GPS and 10K IMU are not part of the program. I'm really happy with the analog devices IMU, now to solve the GPS. I have one more
gps to try the new Novatel OemStar, I suspect that it may do better, but it is not available in a form that does not have the COCOM limits. I really do want to develop a vehicle in the next 12 months that will exceed 1K knots and 60K ft at the same time. There is an open GPS project based on the old Novatel SuperStar, alas the super star hardware is not available anymore and the base band chip set used on that receiver is not available. I can buy a Novatel receiver that is unlocked but it would be about 2K. As I've said several times this year, I currently have more rocket time than rocket $, I can continue to do interesting things with my leftover LLC hardware, but it does not match the far end goal. The far end goal is a 100Km 5Kg payload rocket that is reusable and can be reproduced for less than 10K.

In the past few years there have been a number of interesting papers, and even some 100% open projects on building software GPS receivers with just a simple front end. There are also a number of GPS front end chips and module assemblies that will directly feed such a receiver.
In looking at these projects its clear to me that a high dynamic GPS receiver with real time 10Hz updates is still beyond state of the art for realtime software only receivers. I want to do some experiments in this area, so I'm bread boarding a MAX2769 GPS front end chip a small FPGA and a high data rate SD card to record about 60 seconds of GPS front end data. So some time in the next month or so I hope to fly a payload that records GPS front end data and can be post processed with the open source software GPS receivers. If this works I might think about developing a 100% open Tightly integrated GPS/IMU using these peices, with the high rate code and carrier loops in an FPGA. Having the IMU data available at the code and carrier phase tracking level can really help the GPS keep lock. The short version is I'm crazy enough to contemplate building my own GPS receiver as I can't find one that meets both my cost and performance targets.

For anyone that cares the raw data file for flight #2 at plaster city is here:

The GPS data is at 10Hz and unmodified, the ADIS16400 is shown in the $AIMU lines.
The data is raw from the ADIS16400,(look at that data sheet) the order is Ratex, Ratey, Ratez, Acel X, Acel Y, Acel Z, Magx, Magy, Magz, extra. (I recorded one too many fields)

This flight was a lower acceleration flight on a rocket with big fins so it made a fairly sharp turn into the wind and the flight path was more parabola than straight up. The parachute deployment was also fairly late and abrupt. Looking at the Magnetic data it looks like the rocket rolled about 5 revolutions during the boost phase.

Friday, June 04, 2010

Way to go Spacex!!!!!

From the video feed I saw that launch looked perfect.
Way to go spacex!!!!

Good luck to spacex.

I'm eagerly awaiting the spacex web-cast to watch the first F9 flight.
I sincerely hope they have a perfect flight.
It is a new rocket on a first flight so a perfect flight is unlikely.
If they have a problem it will most likely be something they could not test on the ground.
If I were to guess my biggest worries would be:

  • First stage pogo oscillation, the Saturn V had significant issues with this.
  • 2nd Stage ignition in vacuum, the first stage Merlin's have a fair bit of ground side support equipment, so the air start is a differnt beast. (The first hotfire scrub was do to an incorrect valve in GSE) A turbo pumped motor is a complex piece and getting the whole choior singing in tune on the first attempt in vacuum is tricky.

Tuesday, June 01, 2010

BP Oil spill and Space Robots

If you have been a long time reader of this blog you probably have a geeky desire to see all the technical details. I've been watching the BP spill response with morbid fascination.
BP looks like it is being very open with the technical aspects of its response.
just take a look at all the videos on this page, the scale and scope of the operation are mind numbing. If that link does not work as a permalink, just look for the June 1 Videos on the LMRP, or go back and watch all of Kent Wells presentations.

I've been watching the the technical videos, diagrams and briefings for at least the last two weeks. I think this whole thing could be used as a pretty detailed response to those space scientists that say don't send humans, send Robots. With the BP spill we have lots of very sophisticated ROV's ,they have reasonable access to the surface for repair, adjustment and tool change out, a round trip operating delay of ~10 micro seconds and yet the whole process looks painfully hard. Trying to do any serious resource extraction or heavy construction remotely without direct onsite human intervention is currently significantly beyond state of the art. We need Humans on site.

We need humans in space. Go F9-Dragon!

Sunday, May 16, 2010

Three days in the desert.

The Friends of amateur rocketry is the site where we do most of our testing and flying.
It is both a registered non-profit and a largely volunteer organization. In the last year of our LLC I felt we had become more of a user than contributor to the organization. This week FAR had a three day work party and I spent three days on site. All in all we did a bunch of trenching and in the end buried over a mile of Ethernet and power cable. It was three days of very hard physical work with as much time spent using a shovel as any other implement.

A large part of our culture probably doesn't understand why we as a group chose to spend our personal vacation time waist deep in a trench operating a shovel in the hot sun. The Majority of the people on site (self included) could afford to spend vacation time sitting on a tropical beach with a frozen drink, and choose otherwise.

On Saturday we had an active flight waiver so I took a break and did some experimenting. I'm evaluating sensors for high G use in rockets. I modified the Nose cone of the Liberty 2 I built a month or so ago.

You can see the stock nose cone on the bottom and the modified one on top. The electronics bay slides into the aluminum sleeve and screws in around the base with 10 counter sunk #4 flat head screws. The GPS antenna is on top and sticks up just above the metal/plastic transition. I am using this to evaluate IMU, GPS and telemetry components. It has an analog devices ADIS16350 6 DOF imu and a Spark fun 9DOF IMU (I know its really 9 measurements not 9 dof) A low cost 10hz GPS and a 100Mw Xbee-900 telemetry radio with non-optimum antenna. (The antenna is the white wire sticking out of the base) and 2Gb of micro SD data logger. The goal was to launch it and see how the different sensors compared. Alas the GPS worked at home and never got lock in the field so I got one flight with dual IMU data and on the second flight I pinched a wire reassembling and only got data from one IMU.
I'll review and commend on the data collected later. The flights were around 4000 ft with 8 or so G off the pad and the system seemed to have no telemetry glitches. On the ground I used a simple rubber duck antenna. At this point the IMU data is just one hour of raw numbers, but I'll locate the flight in the data stream and reduce it to something useful in the next week or so.

The CTI pro54 solid HPR motors are really easy to use, the flights themselves were pretty uneventful.

When I flew the vehicle at plaster city I bought a tracker/beeper to help find it. I did not purchase a receiver as the club had one. I put the tracker on with a fresh battery when I flew at FAR thinking that if I could not find the rocket I could go find a tracking receiver and come back in the next week to locate it. On the first flight it did not land with the rocket, the deployment was about 4 seconds late and had some speed so I guess I did not tape it on well enough.
So if someone is a real glutton for punishment there might be a tracker at 220.470 (ch 247) beeping away somewhere in the desert south of FAR.

Lastly on the 25th of this month the local San Diego AIAA chapter is having an awards dinner and Unreasonable Rocket's LLC effort is getting an award,that's kind of cool.

Wednesday, May 05, 2010

Catching up....

A bunch of Random thoughts... Business is picking up and if we can manage the many parts shortages I should be able to fill in the LLC $ hole I dug in 2009 and even do some modest development.

Toward that end I've been working on several things.
The four motors shown in the back of the rocket two blog posts ago are meant to be 3D printed with built in cooling passages. I had a plastic version I was showing at Space Access, the Metal version I ordered arrived today and it looks really good until you try to pass fluid through the cooling passages they are all plugged with sintered metal. Its a really pretty $400 paperweight.
I may have to build in a conventional way or change to a more expensive 3D printing process.
I used a supplier that uses the Prometal R1 and would really like to have the work done on a
EOSINT 270 M, but that process is about 5 or 6x as expensive.

Last weekend I went out to the San Diego Tripoli club launch and Joined Tripoli and successfully flew my Level 1 and Level 2 Qualification flights using the poorly painted Liberty 2 I discussed earlier. I'm in the process of building some test hardware to evaluate several lower cost IMU and GPS solutions that I will fly on the Liberty next FAR weekend (the 15th)

I'm working at doing some development work to lower the overall cost of things. One of the areas I'm working on is a lower cost IMU based on MEMs sensors. The Mems Sensors are getting much better and lower cost. The area I'm sort of stuck on is doing the drift bias correction stuff. The guys at have been working on IMU drift correction for aircraft and have generated some really good stuff. I just started a discussion topic over there that I hope will help me make some progress in extending some of this work to highly accelerated rockets. (

Sunday, April 18, 2010


I've written a very simple simulator to try and do some vehicle optimizations.
Using a very simple drag model... I used the data from page 16 of built a table of mach number and Cd and interpolated. (This is actual data from a 5" rocket, were building a 6" rocket so it seems reasonable)

One of the interesting results is this graph:

It shows peak altitude achieved (y axis in meters) piloted against the equivalent peak drag. The peak drag units here are equivalent velocity at sea level in m/sec. The peak is at 50500m and 303m/sec (165Kft and 677mph)

Another interesting result (from a slightly different run) I'm not using any real fancy integrator and the results vs time steps don't change much:

Time StepAlt

So this means for very crude integration steps you get reasonable results, thus allowing one to use the model for optimization seeking. Right now there are a number of limitations, the model assumes that the ISP does not change as the motor is throttled for peak drag limiting etc... so as I add more detail to the model it will be interesting to see what happens.

Sunday, April 11, 2010

Space Access 10

I had a great time at space access. It was strange to be showing a space access regular the plastic model of the 75lb motor I'm having 3D printed in stainless and the CTO of Lockheed interrupts and asks for my business card. The motors is a 50 to 75 pound regen peroxide hydrocarbon biprop. I've ordered one from the 3D printer and I'll show pictures when I get it. This drawing shows 4 of these tucked into a 6" airframe:

For those of you that follow the blog that was actually the only 100% new picture in my entire presentation. I also talked about restarting my composite tank work that I started in 2006 at the very begining of the blog. (Go back and reread the first few months)

The Technical plan going forward is in several steps. Working on a smaller scale I can do 100% of this plan within my current budget.
1)Build a 4 engine gimbaled monoprop that uses irrigation tubing and HPR style recovery. I expect this to take two months to get ready for first flight attempt, this puts it in the middle of summer so first flight might be delayed until september as FAR in summer is miserable.

1a)In parallel test the bi prop motor I'm having printed.

1b)In parallel develop composite polyethylene lined tanks.

1c)Build some small canards for the 6" airframe and see if we can make it glide with tanks empty.

In no particular order do the following:

Trade out the mono prop motors for the bi-prop. (I'll Probably crash the mono-prop so its probably a series of mono-prop then bi-prop.)

Substitute the composite tanks for Irrigation tubing tanks.(or alternatively put one of Steves Flometrics pistonless pumps in instead of the composite airframe.)

Fly the whole assembly to 100K ft

Fly the vehicle to 100K ft twice in one day.

Seems like a simple list its probably two years work.
The first unpleasant step is to clean up my Garage so I can actually work on anything.

Sunday, April 04, 2010

I hate painting...

I have done a bunch of stuff at FAR, but I've never done the traditional HPR rocket thing.
Some of the next steps (glide back, aerodynamic canard controls) will be done a bit easier with that sort of propulsion. So to be able to order/fly traditional HPR stuff I though I ought to get my Tripoli certification so I can just order HPR motors. Toward that end I built a Giant Leap Liberty 4 kit to do the L1 and L2 qual flights. The Local Tripoli club flew Sat and Sun this week, so I was trying to get it ready for Sunday. On Friday it was done, it just needed paint.

Did I remember to say I hate paint? I put a nice coat of high build auto primer on sanded it all off, repeat three times, its looking pretty nice in its gray primer. Then two coats of white base followed by florescent orange about 10pm last night. Then I went to bed, alas this morning it looks like on the those crinkle paint jobs the white was not dry enough and the orange crinkled.

I took my painting embarrassment out to plaster city to do the qual flights only to discover the motor vendor was only on site Saturday. Arghhhh! Oh and did I remember to say I hate paint.

Sunday, March 21, 2010

Blue is dead...

We had a perfect tether flight on Saturday, followed by a bad free flight.
The vehicle started well, but as airspeed built up it started to spin.
It got to about 1Kft then started down. It went unstable probably due to the high rate of spin.
and started to leave the area of the pad and was heading toward the spectator area so I aborted. Both the software driven and RC only vent abort worked.
The vehicle is totaled.

The micro sd flash chip from the vehicle physically looks ok, but gets very warm when power is applied so I've gotten no data from the vehicle.

I had a camera pointed at the bottom of the motor with a good view of the vanes and if I can recover data from the video camera SD card it should provide some information.
The camera was destroyed on impact, the SD card is fine but the camera did not close the video file before impact. So it shows zero length.

Any advice on how to fix this?
My approach:
I've got some utilities for manipulating bare SD sectors that I use for my data logging cards.
Using this I wrote a utility to copy all the sectors off the Cameras SD card into a big file.
So the original card is safe and I won't mess with that.
I then wrote a short utility to copy the exact same sectors contents back onto a equal sized SD card. I'll then run chkdsk on this duplicate SD card.

One rub is that while the SD cards are the same brand and size they report slightly different numbers of physical sectors, will this mess up the FAT table accounting? The card I'm copying to has more sectors than the one off the camera.

The cards is formatted as FAT16 so I can start tracing clusters by hand and reassembling file chains, but its been along time since I did FAT table stuff by hand with a hex editor.
Any recommendations on good tools to do this?

If that does not work,
any other ideas on recovering the video data from the SD card?

Tuesday, March 16, 2010

Getting ready part N..

I've made my cat pack. I've built new tethers, the only thing left on my list is re zero the one vane I had to take apart and do final electronics checkout. In the next day or so I'll modify the software to match what I'm flying in simulation.

I'll probably leave for FAR Friday night and do a tethered flight very early Saturday. I've done a lot of simulations and a flight to the 1200 ft limit of G airspace. (1000 ft to give me some margin) and back to the pad is easily within the most pessimistic performance parameters. So if the tether flight goes without problems I'll make that attempt on Saturday.

Higher than that and I'll need FAA authorization to enter controlled airspace. (Which they are unlikely to grant me until I actually stop being lazy and formally ask for it. )

When I get that I'll try the flight to 11K ft and back to beat DCX. With out some aerodynamic drag on the way down it has ~3% margin. As a result I've ordered a parachute from Fruity Chutes (blue of course) and I will setup to deploy the drogue at apogee and basically fall back to 1200 ft or so before powering up to land. The purpose of the chute is to keep the vehicle upright and limit the speed to 60mph or so. This will either require a very calm day or compensation for winds aloft. I need to mdoel this. I can just use forecast winds, or I have to study the FAA rules to learn what I need to do to release a small balloon to measure the winds right before launch.
(A small Xbee transmitter and GPS cost less than $100 and is very light so I can actually fly a small instrumented balloon.)

Rough calculation says 11K ft to 1K ft at 60mph takes 113 seconds. So a 10mph wind would cause 1600 ft of displacement. I'll need to be very close on the wind calcs to land back on the pad. I might be better off to fly from the lake bed near FAR.

Saturday, March 06, 2010

Working on Blue and....

Last week I fixed the landing gear on the blue ball in preparation for taking it to spaceup last week for show and tell. (You can see a picture of it there on its new gear here:

Last night I worked on building up a new cat pack. I started with the cat pack from silver and added some new disks. The top third of the cat pack was stripped and dead, I'm not sure what is going on. If I'm overheating the cat pack I'd expect the bottom third to be bad, not the top third. This leads me to believe I have some kind of contaminate in the h2o2. The new pack is ready to install.

My prep list looks like:
  • Remove the bottom half of the motor.
  • Grease lube and inspect bearings on the vanes.
  • Install cat pack in motor.
  • Replace seals in all the sanitary fittings. (This is preventive)
  • Reassemble the motor.
  • Replace the GPS antenna cable. (It has a kink at one of the ends.)
  • Inspect the wiring.
  • Build new Tethers.
  • Do a full electronics checkout.
  • Charge all the batteries . (computer, actuators, abort rx, telmetry box, laptop,2x rc transmitters, 3x cameras )
  • Do a tethered flight (on the 20th)
  • Do a free flight to about 1K ft. (maybe on the 20th)
  • Do a higher free flight???
I expect to finish all but the last four this weekend.

I have almost no traditional HPR experience with things like recovery high speed airframes etc... to remidy that I've been contemplating building a really simple H2O2 monoprop out of 4" or 6" aluminum tubing. Something that could go supersonic and reach to 20k ft or so. I'd use conventional dual stage recovery just like the big HPR guys do. This is something I can do with today's budget. Making the same basic vehicle bi-prop would make it capable of 100K ft.

It would probably be three increasing complex projects:
  • Unguided simple blow down mono prop to learn recovery.
  • Fin guided pressurized mono prop.
  • bi prop.
One of the really cool things I saw at spaceup was Ventions LLC small 100lb thermally
decomposed biprop h202 and RP-5 motors. Dr London had some cool video of it fireing on his phone. The motors were interesitng for both the construction and the thermal decomposition.
The were constructed out of stacked photo etched plates diffusion bonded together.

Getting a reliable thermal decomposed h2o2 motor to work would also be a really cool project.

Sunday, February 07, 2010

Watching STS-130

I'm in Florida to watch the STS-130 Launch. I have NASA Guest tickets and the Launch viewing area is next to the Saturn V display at the Cape. The Temps for last nights scrub were a tad below 50F but the wind was blowing and damp. I did not really pack appropriately for these temps, it was really cold. I left the hotel at Midnight and got back to the room at 7:15 am. My internal clock is saying WTF?

Once again I'm stunned by the scale of the Saturn V, the size of the launch vehicle necessary to put 2 men on the moon in one shot is just staggering. I post and tweet my observations of the launch when it happens. The couple sitting behind us on the NASA bus has come out for 9 shuttle launches and has seen 9 scrubs and zero launches. It looks like they will try again Tonight but Tuesday Mornings Forecast is for worse weather so they probably won't even make the attempt.

Friday, January 15, 2010

Non-rocket but fun...

EDN published a short "Tales from the Cube" of mine.
This happened along time ago ~1990

Saturday, January 02, 2010

Notional Next Rocket...

Its still going to be six months or more before I can really start working on this, but its my next notional rocket. It uses the motor valves and actuators from the Silver vehicle in a more aerodynamic shape. The Green tanks are Wellmate WM12 tanks with the air bladders removed, and the blue tank is the WM-6 that was the fuel tank on the silver. With a 16" diameter and 380 liters of light weight 500 PSI tankage it should go to 100K ft +. Its basically 20 ft tall.
The tanks would be joined together with carbon fiber barrels bonded to the tanks.

Bucket List Item....

I've always wanted to watch a shuttle launch.
I saw the very first shuttle land at Edwards, but I've never seen an orbital launch of any kind.

After a little contact fishing I just received a VIP invite to watch STS-130. Thank you Will and Andrew!
This is a night launch so it should be spectacular.