Status...

• We built tested and installed a new emergency vent valve to replace the one that got snapped off.


• We finished rewireing the top end of the vehicle.


• We repaired the bent vane mount.


• We modified the motor so we can change catalyst orifice sizes.

We are waiting on several next day parts orders but the tasks for today are:

• Reassemble and calibrate the vane actuators.


• Change the position feedback on the main valve to be more robust and visually verifiable.


• Redo the bottom end wireing


• Buy more Tether (clmbbing rope)


• Replace a damaged battery


• Replace all the battery tie down straps as they were damaged by the peroxide.


• Replace the 1” Peroxide check valve with a 1.5” checkvalve.  (One of the parts we are wating for)

 

 

 

 

Going for it...

We are going to keep trying for at least another week. I’ve confirmed that the main valve had sensor clocking issues.

 

 

Notes and Video

(This post won’t make sense witout the previous one) After reviewing the data I think we have two problems. We have some kind of issue with te Motor and consistant throttlings. It may be as simple as having the magnetic sensor that monitors the throttle valve position be wrong/loose.

The second problem is a heavy weights it vibrates a lot more this is causing problems measuring the GPS velocity, feeding back into the target pitch/roll to hold position loop causing the osscilation you see at increasing amplitudes on the video.

No decision on plans for this year. I need to look carefully at the damage.

Here is the video of the fateful flight. (I found it very difficult to watch) I’m still not sure how a vent on top of the vehicle can spray peroxide everywhere when the tank is less than 1/2 full.

Good news we got data right up the the end of the flight, the remote commanded shutdown of the vehicle works, the tethers and vehicle structure worked as designed , and the peroxide cleaned most of the spilled purple menace off of the pad. (It also damaged the tether ropes enough that they need to be replaced)

Murphy is a skilled and devious opponent

We tried a 90 second Tethered hover today. It did not go well. The vehicle would intially lift off then thrust would decay and it did not have enough lift. This may be a catalyst issue. At the same time we had dynamic stability issues at the heavy weight. We tried 5 times and on the 6^th flight we solved the stability issue and murphy struck.  The vehicle lifted off flew stably and  climbed too high. When we hit the abort it got tangled in the tether and with close to 600lbs of weight it crushed all four actuators on the control vanes then fliped over tearing off the emergency event, showirng everything on the rocket with peroxide. The peroxide melted or damaged almost all of the wireing on the vehicle. All in all its probably a “60 hours of work event.”

We need to depart for the contest in about 21 days. We would have to have zero additional “big events” to have a chance. Its been an emotionally trying day. I’ve been up for 18 hours and I’m going to make a probaly futile effort to get some sleep. I need to make a difficult decison in the next 24 hours.

LLC Schedule

The LLC teams had a conference call Sunday at 11am PST to discuss the 2008 schedule. I asked if I could blog about it and was told that I should wait until close of business Monday.

Its Monday and I have not heard otherwise so here is what I know:

The Xprize team is trying very hard to keep the original October 24/25 date. They are currently planning to hold the event at the Las Cruces airport, the same location as the 2006 event. This involves a change in the pad distances and a whole bunch of new coordination. It will be a real rush to get this done in the next 25 days.

When the event was originally delayed I’d been a tad relieved, now that it is back on for the same date I have a boat load of work to do. I could not sleep last night so I got up at 2:30 and started writing. I wrote up a bunch of items to e-mail my FAA contacts and had several follow up phone conversations with them today. They noted with some amusement and possibly concern that my E-mails to them were at 8:30 PM on the 28^th and 4:04 am on the 29th.

I’ve just finished revising my experimental permit application to reflect:

• The Change in Venue


• The Change in pad distances (50 to 100M)


• The changes in the vehicle (Switch from leg tanks to sphere tank etc..)


• Changes in operational procedures that have matured with the recent testing.


• Changes in the order of things accomplished in flight tests.


• Documentation of verification items completed.

I will publish the revised document when the project is complete this year. (I will also publish all the software schematics, and what detailed design notes I have at the same time.)

Now that the vehicle is flying my son is in the process of taking all the spare parts and building a duplicate. As the Armadilo guys told me don’t get too attached to your vehicle you will eventually loose one. Its a hard thing to face and with the upcomming free to altitude (55m) untethered flight comming up its a bit scary.  However we did not build a mueum peice, we built a flight vehicle and when  it is eventually lost thats part of the game. See the last flying vehicle I designed from scratch:Solar Splinter I’d still be working on that project if the FloMetrics guys had not gotten me hooked on rockets. Thanks Steve and Carl! I still have my rare stash of 20% efficent bare back contact solar cells and will some day do that one again.

Slow motion video

Ben Brockert one the the Masten guys came out to watch.The following is a comment Ben sent to Arocket:

With permission from the Pauls I also took it as an opportunity to

test some of the MSS ground support equipment that I'm responsible

for, in this case the high speed camera.

Flight 1, 1/10th speed: http://www.youtube.com/watch?v=JHHQ18jTKDs

Flight 2, 1/10th speed: http://www.youtube.com/watch?v=mXlyE74SdFY

Flight 3, 1/20th speed: http://www.youtube.com/watch?v=cHeWN2XG1CE

Flight 4, first from ground, 1/10th speed:

http://www.youtube.com/watch?v=9-EgMh9lwc0

Flight 5, off-nominal engine burn (steam?), 1/10th speed:

http://www.youtube.com/watch?v=JEVNicWURJg

Flight 6, 1/10th speed: http://www.youtube.com/watch?v=rM_JLIhZLxg

The Right Stuff: http://www.youtube.com/watch?v=Y-h1S9CUORU

We have 3 HD cameras and high speed capabilities to 1200 frames per second. If anyone wants to test an engine or system in Mojave, we're happy to consult and document.

 

Congratulations SpaceX!

I watched the launch, and  it looked perfect.

Way to Go!

 

 

Video

From the ground

From the ground

We flew 7 times today, the primary changes were the addition of 25Kg of payload and some tuning of the vertical loop constants , both turned out perfect.

Flights 1,2,3  Perfect take off from the stands hover for 5 seconds at 1.5M then land.

Flight 4 Perfect Still attached to tether, but sitting on the ground Take off hover for 5 seconds land on the ground.

Flight 5 attempt on take off from the ground only got the ctalyst valve partially opened. We arn’t sure why,  we should  know more when we review the data. It took off, but could not maintain altitude and settled back on the ground in water rocket mode.  No damage. We reset the valve controller and …

Flight 6 the  third flight  from the ground to hover and back to ground was perfect.

The last flight was a very short flight to from the stands to burn off the remaining peroxide from the last flight. It lasted maybe 4 seconds. Again perfect no damage.

Some of the Masten folks came out to watch and Ben got some really cool slow motion footage of the flights. (Look for him to post it soon)  I’ll review data and post a video or two on Sunday. Right now its been a long hot day , I’m grumpy, sunburned and  don’t feel like editig video. ;-)

We have finally reached the point many rocketry people have dreamed about: Fuel is a significat cost. Our next flight series will include a 90 second hover with payload and the peroxide cost for that flight will be noticiable.

After that we need to do a free flight to 50 meters translate out, translate back and we will have completed the testing series required for our experimental permit.

It gets easier

I’m preparing to go out and test again this weekend. Were planning to test Saturday Morning, were goin out Friday Afternoon. There is a FAR workparty trying to put up some shade and we vouelteered to pick up the steel roofing. We need to pick it up around 3:00 PM Friday in Ontario, CA. This means we leave around noon.

I’m spending this evening getting ready. Its the easiest prep I’ve ever done. The only hardware change is to add 25Kg of Payload to the vehicle in the form on srap on Ankle weights on the tops of the landing gear.  Earlier my Son and I  I flushed the Permangenate system and did a full operational check of the vehicle.

Other than that I’m charging all the batteries

• 2 main flight batteries


• 2 Main flight battery spares.


• 2 IIP Abort batteries


• 1 Emergency Vent Rx battery


• 1 Emergency Vent TX battery


• 1 Controller TX battery


• Primary Lap top


• Spare Laptop Battery


• Spare Lap top


• 2 Video Cameras


• 2 Extra Vido Camera Batteries.

16 Total.

The only other physcial preperation is to copy some new anaylisys software to the Laptops and make sure the backup laptop gets updated with all the new software thats on the primary. It looks like the toal prep time will be less than 4 hours! WOOO HA!

If I’m going to fly under my flight waiver (longer than 15 seconds) I need to “clear” the uninvolved from the area. Since I’m going to be working on takeoff and landings this weekend the flights are all going to be under 15 seconds, under amateur rules. This is probably one of the better opertunities to come see the vehicle.

We test out near Cantil CA. If you want to send me an E-mail (you’ll have to answer my spam filter) with contact info I’ll give you a call Friday to discuss how to get there. I’ll be packing up by 11am so later than that and I won’t get back to you. My email is Paul at Romeo Alpha Sierra Delta Oscar Charlie dot Charlie Oscar Mike.

Thanks

When I started this project I wanted to show that significant things could be accomplished by a very small team. With our recent successful flights we have in some ways reached that first goal. We are going to keep striving to compete at the NGLLC, but it also seems like a fitting time to acknowledge some success and explicitly  thank some people:

My son Paul. It has been a privilege to spend the last 18 months working so closely with my son. He has done most of the non-electronic physical fabrication. He has also been invaluable is a huge number of logistics issues like making sure we have a crane, propellant, catalyst etc…. The project would not be remotely possible without him. When I was his age I spent two years working on a race boat project with my Father, I know it is not always easy.

My Wife Mariellen.  My Wife has been 100% supportive of me and my insane project. She has helped me keep an even keel during the inevitable ups and downs. She has been completly selfless as my Son and I have been absorbed by the project. Without her assistance none of  our progress  to date would be possible.

Charles Pooley of Microlaunchers. Charles has spent many many long days and nights at the FAR site providing us a helping hand. He has offered countless small suggestions. he is an invaluable resource into the history and methods of rocketry at all levels. He has always been available to help and has been an invaluable member of the team.

Beyond these three there are dozens and dozens who have helped, in no particular order, Steve and Carl of Flometrics, Bob our welder, Tom and the rest of my coworkers at Netburner, Kevin, Mark and Ted of FAR, John Newman,  John Carmack and the whole Armadillo team, David Weinshenker ,Mike Carden of XL space systems, Mike Kelly, Wynn  and Nick on my FAA team, and many many more.

Bonus videos

Fairly good attempt at a 5 Second flight with a Landing….

Diizzy footage from on board during the “Plus” flight.  I cut the start a bit too tight and missed takeoff…

 

Code Test....

Given the following snippit of C code we are attempting to add damping or differential correction to the pitch stability. The values gain and DiffPitchRoll are constant doubles used to adjust the various gains.  This chunk of code runs 75 times a second and er.Pitch is the IMU raw pitch output. Given we want rate damping what should the sign of the differential correction be ?

/*****************Code Snippit *******************/

 static double pitch_prev;  
 double cur_pitch=PitchConvert(er.Pitch);
 double pitch_err=Target_Pitch-cur_pitch; 
 double pitch_change=(cur_pitch-pitch_prev); 

 Elevator_Correction_Cmd=(-((pitch_err)*gain))?(pitch_change*(double)DiffPitchRoll);

 pitch_prev=cur_pitch;

/*****************End Snippit *******************/

 

What should the Red ? Be?

If you choose ‘-‘ goto this video: Minus Video

If you choose ‘+’ goto this video: Plus Video

(We have a tethered burn time waiver inplace.)

The vehicle was undamaged in both videos above,  We need to work on the altitude control a little bit more and we did eventually tangle the ropes around the the GPS antenna mast 3 flights after the “Plus” video and broke it off….all in all a good day.

 

 

 

Testing again...

We plan on testing Sunday Morning. As A side note the contest has been delyayed at least a month. I have mixed feelings,  I really need the month, but I was also looking forward to being doen.From a fairness standpoint this is really unfair to armadillo.

 

 

 

 

Schedule...

I got up at 6:30 am on Tueasday. I went to work and did a few hours of “Support”. I spent the balance of the day double checking everything on the rocket. We left the house at 8:30 PM headed for  FAR.  While filling the truck with gas  I noticed something on the vehicle was rubbing that should not be rubbing back to the house realign the main valve and leave at 9:15PM arrive on site a 1:00 am. Sun comes up at ~6:30 finish unpacking and setting up the vehicle. First thethered flight attempt at 9:00 am. The first attempt is a no launch as we had made some adjustments to the “Throttle controls “  and we had a sign wrong on the vertical acceleration. Played with software for an hour tried again. Between 10:am and 6:00 PM we did 8 or 9 short less than 10 second flights. We were trying to squeze in one more flight before dark, alas the data reduction from the previous flight pushed us past dark. We packed up in the dark and left the site at 8:30PM We drove to Mojave had dinner and then drove home. Arrived home at 1:15 AM. I slept the first half of the drive and drove the 2^nd half. I’m now wide awake (and hence everyone gets an update) Many thanks to Charles Pooley and Kevin Baxter for their help today.

Good news and several problems:

Good news: We had almost no  hardware or electronic issues, we had 8 or 9 flights with ZERO damage. We got data from all but one flight and good video from two or three angles for each flight.

Problems:

1)The motor is really inconsistant. I think there are issues with the catalyst. We had clogging issues with the aluminum plumbing, we now are all 100% stainless, but the catalyst still has issues, we are going to flush the system and see if anything is clogged. My guess is that one of the checkvalves or orfices is clogged.

2)The Helicopter manuvers differently than the rocket. When you tip the helicopter to the left, the helicopter moves immediatly to the left, when you tip the rocket to the left, the vectored thrust act of tipping actually moves you to the right. The helicopter also has a  LOT more damping than the rocket does. I think we need to add an explict pitch/roll rate loop to the code.

3)The Rocket is really sensitive to the horizontal CG we need to balance better.

4)Minor: A Black plastic pelican case (Holding the telmetry radio) gets WAAAY to hot in the Mojave sun. IT needs to be shaded or it  starts getting flakey. When we found this problem it was TOO hot to touch.

 

Testing again...

We are headed out to test on Wedensday.

I’ll update when we return.

 

 

Video

The Video is up on you tube.

I’ve also posted a higher quality version myself.

Please download and view rather then veiw online as the keeps me under my bandwidth limits.

 

Paul

Test Results

We did one tethered test this weekend.We intended to do a 10 to 14 sec stable hover at 2 meters in altitude. It seems like the throttle gains were a little bit aggressive as the vehicle was very lightly loaded with fuel. It jumped up to 3m  and started to swerve  in pitch .as the throttle over compensated and interacted badly with the pitch loop. To protect the vehicle I had set aggressive abort limits (20deg in pitch and roll) It hit the abort limits and shut down. The vehicle coasted up to 4m then began to fall  while slowly continuing to roll in pitch. When the tethers came taught at the bottom the vehicle was almost inverted. I had used PVC tether covers like Armadillo does, but I had not secured them in position on the vehicle. they slid up the tether ropes and formed a loop that caught around the peroxide vent valve and the primary flight control battery. When the lines snapped taught it removed both the vent valve and battery.

The Tethers absorbed the shock and prevented the vehicle from contacting anything other than the tethers. Other than the vent valve and battery mount the vehicle is undamaged. In reviewing the video the I am very pleased with dynamics of the tether system.  I inspected the tether mounts on the vehicle and saw no signs of damage or distress from a fairly severe usage.

As soon as I saw the vehicle abort I reached for the command abort RC transmitter to depressurize the vehicle. The removal of the main peroxide vent started the de pressurization, but that vent is VERY small, so when I activated  the emergency vent one heard a distinct POP and  large woosh. Lasting less than a second.

The 900Mhz primary telemetry channel is used for both data status download and command upload. To insure reliable command upload I've reduced the data coming down from the vehicle. The largest part of this data is the IMU data and the control loop responses.  I record 100% of all vehicle parameters at full rate on board   on a 2Gbyte micro SD flash card on the vehicle.  this recording process has between an 1 and 2 second delay. As the tether loop removed the vehicle battery we lost the last 2 seconds of the 2.5 second flight.

Anomalies and corrective actions:

Emergency Vent:

The emergency vent uses off the shelf COTS RC equipment. the servo arm and linkage controlling the vent used to be plastic.  It looks like chemical and weather exposure made the linkage brittle and we broke it when preparing the vehicle for flight. We repaired it in the field with some safety wire. (Its in tension to operate the vent) and it operated  correctly as indicated above. We are going to replace this with a proper  all metal linkage before we fly again. The present wire linkage will actuate  100% reliably, but it might also allow it to activate without being commanded.

The Tether ropes:

The dynamic 9.5Kn climbing rope worked very well. The PVC pipe covers did not work correctly.We have already modified these to extend them and retain them on the vehicle end to prevent rope loops.

Pressurization Quick disconnect:

The dual pressurization quick disconnects were actuated twice, the first time only one of the two disconnected. After de-pressurizing the vehicle and trying again both actuated.  As the vehicle was up on blow out stands we could not pull on the end of the hose as we could if the vehicle was on the ground. So in a "real" flight its likely that  we could have recovered from this failure.  The disconnects were designed to be rugged as they will fall to the pavement after every actuation. The one that failed to deploy  had been "Adjusted" by prior test impacts.

Control laws:

We have already modified the throttle control loop to change the behavior and we intend to try again on Wednesday.

Hardware:

We repaired the valve and attempted to re-fly on Sunday, but  we had intermittent computer hardware issues and choose to return to San Diego to evaluate.  We evaluated this on Sunday night and it looks like an epoxy blob we used to pot the wires coming off the PCB lifted a an IC lead.  The cause and effect is unclear here as another lead of this IC (Not under the epoxy blob),could be displaced with a probe and appeared not to be  soldered. We are in the process of swapping out the primary carrier board that holds the peripherals for the flight control computer. We will get that assembled today and I will probe every single IC lead solder joint under the microscope before installing it in the vehicle.

 

I will try to post the vido in the next 24 hours.

First Tether Flight

We had our first tether flight today. Not perfect, but ok. it was stable for the first two seconds or so, but then we had some throttle osscilation shutting off thrust completly and hitting the tilt abort limit. I'm still reviewing data to learn the order of events. The Tether system worked as designed with only a very minor damage to some vent plumbing on the top of the rocket. (Caught on tether rope, the PCV tether covers ALA armadillo were not long enough.) Plan to review data and video this evening and try again on Sunday. Posting from the Mojave Best Western so no video or pictures yet. It flew, and its still flyable.

Paul

Preperations...

Just finished the Vane direction test. I have the vehicle hanging from a hook in the garage roof. It can be easily tipped or twisted. Its high enough that you can lie on the floor under it and observe the vane movement. For this we assume that the GPS has no fix and thus  the IMU is setup to try and hold a constant roll, pitch and yaw of 0. I exaggerate the gains and tip/twist the vehicle and observe that the vanes move the correct direction to counter act the roll pitch or yaw. It was working perfectly then it would suddenly pitch over and act strange.

After several trips through the code I realized that the GPS was getting a fix and it was trying to navigate to the next way point. Very surprising because the garage roof is where I store all my thing sheet metal so I would have bet there was zero chance of a GPS fix. In any case it looks like it is still a go for a Friday departure and a Saturday test.

Fear

If all goes well we will do a tethered hover this weekend. We have worked on this for close to two years. This weekends test comes with a good bit of fear, not physical fear, but emotional fear, its hard to work on a complicated project for this long and not have a million small doubts. 

One could always wish for another 6 months to test everything 9 ways from sunday, but eventually you have to give it a try. The helicopter is almost exactly  flying the hover test profile we want to fly. I’m a little concerned that we don’t know the exact gains for the throttle valve so I’m going to do a test of the helicopter where the software attempts to learn the helicopters collective gains in real time in flight. I’ll use this on the vehicle. (Update Thursday mornings helicopter gain test worked as planned)

North to the prize.....

The problem with the new software is a heading issue. The vehicle is supposed to stay pointing north, it wanders as much as 30 degrees. This causes a cross coupling between the E-W Roll and N/S pitch corrections. I still have not figured out why the new software won’t properly hold a precise heading, but I added the full heading coordinate transform to the main flight control loop and it works! On to the next problem….

 

 

 

Software Woes

A long time ago( a year ago) we had a software design.

We created a code structure for this software that matched this design, and then it branched.

One branch turned into vehicle control software optimized to run static rocket tests and gather data.

The other branch learned to fly the helicopter.

Over time the two branches grew and mutated until they were not really recognizable as twins.

The vehicle branch controls all the rocket actuators and  logs data while running static tests.

The helicopter branch hovers the helicopter in place and successfully moves it to a selected 3D waypoint.

The vehicle branch gains such things as differential GPS and a flash file system to record data.

The helicopter branch gains things like status LED’s and remotely programable modes selectable via the RC transmitter.

About a Month ago as the physical vehicle reaches completion we started working to merge what is common in the two branches in preperation for hovering the vehicle.

We split out the parts that are defferent between the two vehicles into vehicle specific modules and merged the parts that are common.

This merge took about two weeks and the merged software passes all the ground tests we can throw at it.

The merged software almost flies the helicopter, it is just a tiny bit unstable. The helicopter holds position sort of and if its not disturbed almost flies, disturb it and it goes into ever increasing wobbles….

So we added the ability to tweak the control system gains in flight and flew the helicopter, we reverted the GPS to WAAS mode and flew the helicopter, we played with gains and flew the helicopter, we stuck the tail roter in the dirt, we fixed the tail roter, we flew the helicopter, we stuck the tail roter in the dirt we replaced the tail roter gear box, we adjusted gains , we flew the helicopter, we adjusted gains, we stuck the tail roter in the dirt we replaced the tail roter belt, we flew the helicopter, we had a dumb thumbs moment while trying to check the blade tracking in manual mode, and we replaced the gear, the training poles, the main roter blades, the tail boom, the landing gear, and the tailroter ie rebuilt the helicopter, and we adjusted the gains, and our hair turned grayer, and we swore at the helicopter.

We went back to the source control, checked out the last version of the Helicopter before the attempted merge, we reverted the the GPS to WAAS mode, and we flew the helicopter. It flies perfect…..arghhhhhhhh!

So we know its not the GPS, not the IMU, not the servos, not the helicopter mechanics, or any thing else it’s the software and as far as I can tell the control laws and delays are identical, just rearranged into different files.

Test Results soon...

The Static test went off well. I still need to reduce data, but visually and audably it had good decomposition. The only technical faults were a problem with the auxilary data recorder (did not like the 200M Ethernet cable had to add a hub) and my brand new 2 month old video camera was DOA. So I recorded no video, but Charles Pooley got a good still shot from inside the block house. Thanks for all the good luck wishes.

This picture was partial throttle, we throttle the Peroxide, but the Permangenate runs at full tilt for the entire run so at low throttle we get an excess “Purple” haze. We Arrived about 7:30pm. We got the vehicle on the tower, strapped down and  were all ready to load propellants at 8:30pm. So we spent the night watching the glorious stars in an absolutly perfect evening, 75 degs and a light brreeze. We got up  loaded propellants and fireed at about 7:30 am. We were cleaned up and drving away by 9:00 am.

 

Once more into the desert....

It’s 2:30 PM, we leave for the FAR site in about 10 minutes. We hope to do another static test at daybreak Sunday. Wish us luck.

 

Paul

More Random Thoughts

The contest is in 60 days. Based on what we filed for our FAA application we need to do the following tests:

1. Full Vehicle Static test (Already done well enough to satisy the FAA, but not well enough to satisfy us)


2. Tethered Stable Hover Test


3. UnTethered Stable over Test


4. NG-LLC Simulation up/down translation test


5. 90 Second Hover Duration Test (could be combined with #4)

the location we test is a voulenteer effort, we can only really test on the weekend, we have te following days until the event: 

• Aug 30–31


• Sep 6–7


• Sep 13,14


• Sep 20,21.


• Sep 27,28


• Oct 4,5


• Oct 11,12


• Oct 18,19

We have to buy the event insurance at lease 30 days before the event. ($30K to $50K)So we have 4 weekends before the insurance trigger The Aug 30,31 weekend will be spent retrying our static test, provided I can resolve my issuse before then.

Some thougts on the problems. We have three problems:

Our Permangenate flow is not what it should be. We designed this system to just turn on the permangenate and let it flow at 4% of full thrust for the duration of the flight. This is done via a blow down system with the permangenate stored in the  the legs. In our last test the legs depresurized before the end of the run. It was quite clear that we have a leak in the presurization side of the system. It could be Sliding O-ring Seals on the Legs, Leak in the plumbing, leak in the vent valve.

Our Throttle valve seems to have to poor of control for the peroxide flow, at 20% open we have full flow. So we sill need to reduce the size of our main valve. I’m going to try and accomplish fixing both of these this week.

We have big osscilations in the chamber pressure. We are goin to add some baffels, possibly reduce te size of the chamber slightly.

 

 

Static Test today....

We did a static test today. Ilearned several things:

• Our new software is working.


• Our new auxillary highspeed data collection  is working.


• We got really good data.


• We have a chamber pressure osscilation.


• We still have catalyst plumbing problems.


• We probably need finer control over the throttle valve, maybe the next smaller size butterfly.

I’ll post some of the data in the next few days.

The Shoe makers children have no shoes.

The Software guy’s rocket has no software. I’ve made my living doing embedded control software for about 25 years. I am the software architect for my company Netburner. NetBurner does not do much end use software, we put together devlopment environments that others use to build products. Somewhere in the world there are around a  million embedded devices running my/our NetBurner RTOS and TCP code. Things like:

• Slot machines


• Traffic Lights


• Cow Milking Machines


• Machine tools


• Test Instruments


• Smart Home Theater controllers.


• Self Checkout systems.


• 3D Laser Log scanners.


• Atomic Time Standards.


• UAV’s


• UWV’s


• Buses


• Custom Cars


• Custom Boats


• I’m not 100% sure but from the problem description a customers is running a “peep show controller.”


• etc… etc…

The Hardware is 100% complete on the rocket. I’ve unit tested all the comm links and subsystems. I was hoping to be ready for a final fullup static test with ALL of the flight ready software in place this weekend. Alas I have a bug, the worst possible kind a “hangs up and goes silent bug”. I’ve worked on it all day, and its kicked my butt. On Sunday I’ll modify the watchdog hardware to trigger a non maskable interrupt rather than a reset. Then the NMI routine can give me a little info about where its hung up when the watchdog goes off. Arghhhh!

 

 

 

 

 

80 Days.

We have 80 days. I just re did my to do list. A PDF of My Todo list.

Time to panic.

Reality is we are only going to have the 90 second vehicle ready.

Most approproate team theme song: Up all night by the boomtown rats.

Most apropriate team saying: “Sleep is a no credit elective.”

Good news/bad news… Bad news the Team sponsorship I was working on fell through, the good news is my primary business has been having a good year and money to finish and compete will not be an issue.

 

 

Spacex and Hardware is hard.

This weekend I spent Saturday afternoon glued to my computer watching the drama that is a spacex launch. The Launch once again proves that hardware is hard.

When he started SpaceX Elon had never managed a company that builds hardware. Elon is a really really smart guy and he will  learn to build hardware, it just won’t be as quick or as superior to dinospace as the original power point slides said it would be .  I visited spacex about two years ago. The Staff was very young, a lot of fresh out of college  enthusiastic kids. It was probably the brightest group of pure brain power I’ve ever encountered.   Elon created a vision that was bright enough to attract 100’s of the best and brightest to actually get their hands dirty and build real hardware. They choose spacex and not web 2.0 or  wall street.  SpaceX now has 500 + employees and as these bright young minds learn to build real hardware they will become an invaluable national asset.  I hope they can get up and try again and again, it may take another 5 years until the organization learns what really matters and what doesn’t. Just don’t give up, I for one will enjoy watching them succeed.  If I could give them one piece of advice it would be to  remember to play a little bit along the way. The spacex director of propulsion Tom Muller not only used to work on rockets professionally, he built rockets as a hobby. Tom used to build and fly small liquid propellant rockets out at the RRS. This lesson should not be lost , things one builds with ones own hands teach valuable lessons that are not to be found in any text book.

This was also a sad week for another Software guy builds hardware story. Vern Raburn was Microsoft employee #18, he was very successful at Microsoft. 10 or so years ago he started Eclipse aviation and set out to turn general aviation on its head. He planned to build thousands of light jets sell them for less than 1M and change transportation as we know it. It did not turn out to be as quick or as superior as the original power point slides said it would be. When Vern started there were no very light jets, today there is the Citation Mustang, The Eclipse 500, and soon to be offerings from Diamond, Embrair, Piper, Cirius and others. Vern changed general aviation, he just won’t be running eclipse any longer, he was recently replaced as eclipse CEO.

Hardware is hard is a lesson I’ve been learning for a long time. My very first full time job out of college was for an 8a set aside minority owned business. The  company had been quite successful doing paper research reports.  The president of the company kept seeing RFQ’s go by his desk to build hardware he thought “we can do this”. The company went from 0 to 40M in sales in 4 years, it went from 40M to zero in 12 months. It imploded when all the hardware jobs had huge cost overruns.  

You can see the same scenario repeat itself over and over.. John Carmack started Armadillo 8 or so years ago. The armadillo team has learned to build low cost robust hardware, but its taken years, they had to re learn lessons that every hardware builder must learn.

My final thoughts:

• Build and fly more, simulate less.


• In simulation plumbing never leaks.


• In simulation things never catch fire.


• Simulated parts never have defects.


• Simulated parts always meet their data sheet specifications.


• In simulation your are never told that  we are out of the letter ‘a’ more ‘a’s will not be available for 6 weeks. best to brush up on your other vowels.

Safety Software.

If you read my Experimental permit application ….

a)You won’t have insomnia and

b) you will realize that there is a 100% seperate safety computer box.

That safety box has not been necessary to test things up til now.  Now it is becoming the limiting item to be ready to hover. It receives commands from the flight computer, data from the GPS , data from the RC receiver and sends status to the main computer and commands to the catalyst valve.

 

Since this code needs to both be very reliable and well reviewed I’m taking my time on it. At this point the following is complete:

• Drivers for all the hardware interfaces.


• Parser for the GPS messages (as well as a no message received time out mechanisum)


• Method for storing waypoints and  managing their validity.


• Command parser interface between the Main flight computer and the IIP computer.(Last years version did not have this communications, but this years relies on the II computer to turn the cat valve on and off so the main flight computer needs to tell it when it wants in open/closed)


• Valve driver.


• Battery monitor.

Still to be completeed :

•  Actual IIP code as outlined in the experimental permit application.


• Test Harness code to run on the PC.

 

. After that is complete I need to hook it to a test harness and excercise it. The test harness will look like:

So I have to write a simulator that runs on the PC and flies the veichle around and out of the “box” its supposed to stay in and test what  the IIP computers response is. that will be a significat portion of me weekend. (We also hope to go out to the desert and test again this weekend.)

Very Strange...

I posted this graph a few weeks ago:

The very strange thing is that the chamber pressure is 500+ PSI where the feed pressure is 250 or so. I believed I had a data collection anomoly. I do not. I just finished testing the pressure transducer and checking out the wireing and it is all correct. The calibration of the ggraph is also correct.

The mechanical schematic of my motor is:

So the only possible conclusion is that I have a resonant pulse jet with the check valves. I’m going to run it again with a lot higher pressure and higher time resolution pressure transducer in place.

 

 

 

 

 

 

A Simple little thing..

We are running the main tank pressure on the vehicle at very close to the absolute minimum spcified by the FAA experimental vehicle strucural guidlines. Our design pressure has a safety factor of two, but our test pressure has a SF of 1.25.

What does this mean? It means that no human should be within the blast radius while it is presurized. This implies a remote actuated quick disconnect.

A simple thing in concept a whole afternoon in acutality. The Quick disconnect needs to be reliable, and rugged. Each time its actuated its going to fall from several feet into the dirt or onto concrete.

Here is the result:

Two Aluminum arms are hose clamped to the barrel of a normal penumatic quick discconnect. These arms are fastend to the nut at the front end of an aircylinder (Mcmaster carr 6498K171) The plunger of the air cylinder threads into the back side of a brass plug that has been taped to match the aircylinder rod end thread. The brass plug pushes on the brass Tee and the aluminum arms pull the QD free. It works really well and is almost insdstructable.

 Here is the totally bogus video tour.

Telemetry, Software, GPS, and progress.

Sorry for the long delay in the blog posts, all is going well its just been a busy summer.

I’ve been doing embedded hardware/software development for a very long time. (More than 20 years) One of the things I’ve learned is that you NEVER ever ignore a glitch. Even a harmless glitch. If you don’t exactly understand why its weird, find out. I’ve had a long running glitch in the Helicopter systems telemetry. Since this is the same exact software base I’m going to use on the rocket I needed to hunt it down before I was willing to risk the rocket vehicle.

In our last outing to the desert we packed up to go home around sunset. In the haste to get going I set something very heavy on the telemetry suitcase and by the time we were off the dirt road it was crushed. It looked like a sturdy aluminum box, alas that was only an illusion. So since my last update I’ve rebuilt the telemetry ground station in a ,much sturdier Rugged Pelican case.

In the process of rebuilding that I’ve also been working to hunt down the telemetry glitches and to add a Differential GPS correction to the system by having a differential reference GPS receiver in the telemetry suitcase.

All of these pieces don’t seem like much but these sort of details all take time. So I have this all worked out. The Netburner/Coldfire cpu in the telemetry box automatically initialized the differential GPS receiver and starts sending these corrections over the telemetry link, while the helicopter send telemetry back to the telemetry box through the same link.

Getting all these pieces to talk and coexist without ANY glitches has taken me close to three weeks. Some of the problems on the way were Bad GPS antenna cable, misunderstanding the GPS manual on how to set up differential, dead Maxstream telemetry radio, incompatible Firmware revisions in the Radios, and feature creep in the helicopter where we were trying to send more data that the link could handle. I also took the 4th of July off to relax. I also spent some time cleaning up the helicopter code base as to make the rocket and helicopter more similar from a software standpoint.

I offered to write up the code for the helicopter project for a magazine and it looks like that will turn into a several article project. Probably only one of which will get submitted before the contest in October.

We hope to go out to the desert this weekend and finish welding the Tether Crane, we’ll probably go out Friday afternoon and spend the evening/ night welding as working in the day time is insane. (its supposed to be 103 Friday)

The news from the FAA is all good so far, our review is underway with only minor clarifications needed.

Lastly I’ve been talking to a company that might provide some sponsorship, its an almost ideal fit and I have high hopes. Sponsorship is not absolutely needed, but it would also be nice to extract some value from the “Unreasonable” effort.

Paperwork as Promiosed

My FAA application has been declared Complete Enough. You may read it here:http://www.rasdoc.com/FAApermit/Public_Permit90_2008.pdf

The really hard core can compare and contrast with last years here:

http://www.rasdoc.com/FAApermit/PermitSubmission.pdf

I’ve given up on my Video camera, last tyime I moved it away from the action and had it zoom in, it still cut off part way through the test. I’ve ordered a new HD camera from Amazon that uses all solid state storage. I have high hopes it will be better. Please note that in the last section of the video we were sweeping the throttle valve from 0 to 100% trying to map chamber pressure.  Video is Here

I reviewed my Data and I found two problems….

1)Only one of the three legs is properly feeding catalyst. This explains the early shutdowns.

2)The chamber pressure transducer calibration is wrong, as this is a 4:20ma transducer, and the zero is in the right place I don’t know what is wrong. I’ll have to do a pressure sweep.

Uncaled Data below:

 

FAA App is complete enough...

I’m back from my trade show in Fl, I hope to catch up on my Unreasonable data this week and publish results from last weeks test. I’ll also be posting my FAA application as it has beed deemed complete enough.

 

 

Got home at 2:25 am

It was a 22 hour day. We went out to the desert and poured concrete for 6 hours then began rocket testing. We poured the anchors of our tether testing trapeesze, and helped finish the flame trench on the FAR large vertical test stand.

We did a short 15 second or so test fireing, at full throttle. We ran out of permangnate before we ran out of Peroxide. Other than a tie down problem during setup that was the only issue.

We then helped someone else setup a test (can’t talk about it).

After their test we tested our vehicle for longer duration, it was supposed to be a minute, but again we ran out of permangnate early, we need to adjust the permangenate flow down.

We tested throttling and vane actuation, everything worked it was a very positive test. I have video of the first test, the camera shutoff during the second test. I have had zero time to review anything as I have a plane to catch in 2 hours and I will be doing non-rocket business stuff until next week.

I’ll post data a video when I return.

Its:445

I’ts 4:45 am I have the its to early pukeing feeling. We are going to the desert to test. The vehicle is 100% physically complete. Every bracket, valve, cable, screw, nut and bolt. I still have some software to do, but the physical part is done. If this were more than a static test we would probably not meet the crew rest rules.

I’v finished the revised application and submitted it. I expect it to be declared complete enough.

I’m out of town all next week, I’ll try to post results before I leave.

 

 

Paperwork Update...

The reason I could not origionally  publish this years application was because the location information was under NDA/uncertain. Now that Xprize has formally announced its not under NDA.

In the interim I received a letter from the FAA asking for some paperwork changes.

So now that the venue is now public the document needs revision. I hope to resubmit the application this week. When it is declared complete enough I will publish it like I did last year.

 

 

 

Something different....prizes

I’m sorry I have not provided much input in the last two weeks I’ve been working on a bunch of related issues, but not making much direct hardware progress.

I’ve seen much on-line discussion of the Google Lunar X prize. Its a cool prize and significant purse, but I think it pales in comparision to the briliance of the origional X-prize.

I think a good prize should have several charactoristics:

1. It should seem like its possible to win a bunch of $. A prize that costs 15M to win 20M is not a prize. There were a lot of people that thought they could win the origional X prize for less than 2M, they were wrong, but it appeared at first blush like it was possible.


2. When the winner is successful it should create a market. The origional Xprize kick started a rush to do suborbital tourisum.


3. The rules should be very simple, the core concept should be a paragraph or less.

I think the world really needs a low cost access to orbit prize. The primary barrier to becoming a spacefaring civilization is the cost to orbit. The traditional players have no incentive to really change this.

Pauls Ideal Orbital prize:

• 10M for the first group to orbit a reusable vehicle.


• Must orbit at least 4 times above 100 km.


• Must return intact.


• Must repeat within one month.

Reusable means:

• All stages are recovered and reused.


• No more than 10% of the inert stage mass may be replaced.


• The replacement/refurbishment does not cost more than 100K per flight.

Possible Modifications:

• Change the amount to 25M and require it carry a single person. For the first of the two flights the person could be simulated. (IE record accelerations temps, pressures etc.. prove person could survive.)


• Remove the reuseablity requirement and substitute a low cost requirement. IE a fullt accounted cost to build and launch the 2^nd flight for less than $200K.

Enough pontificating for one day. Those of you who have followed my blog for a long time will know we lost our 15yr old dog in October. Last Friday we acquired a 3 month old puppy from the Hellen Woodward anmial shelter. I’ve spent the weekend playing with the puppy, I only built one rocket part all  weekend.

Paperwork and other projects....

We tried to do a full up static test on the vehicle last Sunday and again on Tuesday. We had some valve electronics problems that were traced to a screw rubbing in a bad place and a dead, possibly overvotaged, servo motor. This last weekend we worked on the logistics issues at FAR and will continue to do so for at least two days this week.

Since my 90 second vehicle and notional and 180 second vehicle are less than identical we need to submit two seperate experimental permit applications. 90% of the 2^nd application will be cut and paste, but we still need to submit two. I finished the 90 second application  and e-mailed and fed-xed it to the FAA. If anyone read last years application this one will look stuningly familiar. I will make the aapplication public at some point in the future. If I released it now I’d be violating at least one NDA. 

I must give special thants to my friend Carl at Flometrics that spent part of his weekend doing CFD work to help me get a Cd number for the vehicle and the containment calculations. If you need a fluid or flow engineers please call them. They do a lot of really cool stuff. I’ll post some of the cool CFD pictures in the next few days.

We have been working at this full tilt for almost 18 months straight and I’m getting a bit tired. Spending a full day in the Mojave at over 100F really takes it out of you. 

A Glimpse of scary little details...

I have not reduced the data from last weekends first static fire, but I know that we had a main valve calibration problem. Tonight I brought up the flight computer to work on the main valve calibration and I got prodigious quantities of magic smoke. (All electronics runs on magic smoke, if you let the magic smoke out it stops working.) This is scary on a number of levels. If the main flight computer dies in flight the vehicle is lost, so I start asking did I make a design error, did I have an assembly error? What caused the system to let out the smoke?  So I remove the computer from the vehicle and take it into my office/lab in the house and hook it up to the current limited power supply…. no smoke. The magic smoke happened inside a closed case so everything in the case smells so no clues there.

One by one I test the sub systems… Main CPU, OK,Vane control OK, GPS OK, IMU interface OK, Telemetry Radio OK, Servo drivers OK Pressure sensor power error not OK. So I examine the little sealed DC to DC converter component that provides this power and it is failed shorted with smoke /char marks under it. The good news is that this failure would not have caused a crash, a loss of  pressure transducer data, but not a crash.

This little power supply adds to the head room for the two wire pressure transducers. I use 2 wire 4 to 20ma transducers because of the reduced wiring, from the three wire transducers. The transducers need 10V minimum, since I run the into a resistor that makes 0–>5V from 0 to 20ma I need a 15V supply. I’d been running 11.1V to the Big tonegowa servos so I added a 5V isolated DC to DC to bring the voltage up to 16.1V. In past setups I’d added one very small sensor battery,  but this time I though I’d remove one more service item. The sad part is that this is not really necessary anymore. This time around the Vane Actuators need ~18V  so I already have a voltage rail, 18V that could drive these. The smoking power supply has been voted off the project.

I wired a sacrificial 1/8W carbon 20 ohm resistor between the sensor circuit and the 18V supply so I’m now good to go. If any of the transducers wiring gets melted and shorts to ground the 20 Ohm carbon resistor will act as a  fuse. Protecting the flight critical power rails.

We also learned another lesson tonight. With LOX you can be 100% sure its gone two days later, not so with peroxide. We ran the vehicle until there was noting but nitrogen coming out of the motor. Apparently this is not enough. When my son  removed the main valve it dumped peroxide on his jeans.  No harm done, but it was exciting for a second when he leaps up removes his pants and runs out of the garage heading for the garden hose… on the way by saying “make sure we there's no fire”  Fortunately none of the many fire extinguishers were necessary.  a few teaspoons of peroxide  makes for some excitement but in this case not much else.

This does say that our run tank and main valve is clean and properly passivated.

Starting the paperwork...

We do not yet have an offical contest date for the 2008 NG-LLC. If they hold it around the end of October like they did the prior two years we are rapidly comming up to the FAA experimental permit submission deadline. So for the time being I’ve switched from aluminum to documents as my development mediium of choice. I feel this will be a lot easier this time around as I’ve already been involved with the FAA permit process.

For fun a cool picture….the business end of the vehicle taken from the flame trench of the test stand….

And one taken from inside the block house by Charles Pooley of the partial throttle test….(the wind was really blowing…)

Tease Picture...

Its light….

A tiny bit of hardware...

The vehicle is 99% complete. The only part missing is the IIP shutdown safety system. The IIP shutdown safety system calculates the instantaneous impact point (IIP) and shuts the vehicle down if the vehicle leaves the assigned flight hazard box.  The vehicle has been transported out to FAR for a static test in the near future so I don’t have a complete vehicle picture. I do have a couple of detail hardware pictures…

The electronics box lid off and lid on….

The box mounts on the side of the sphere at an angle and the GPS antenna mounts on the box so it is the highest thing on the vehicle.

Lastly a short video of the jet vanes moving.

Quick update...

Having Dad here for two weeks has slowed progress, but not stopped it.Last weekend I managed to fabricate the cwenteral control box and it is now wired. The vehicle is now basically complete. We will do a full vehicle tied down static test some time in the next week or so. This should allow us to gather some vibration data on how the IMU and GPS react to rocket vibration. After that we should start testing within the month. Its getting perilously close to the hot season out in Mojave so time is getting short.

We also need to restart the FAA paperwork process so we can do some free flights.

 

Level of commitment...Budget and Life.

Level of commitment.

A Number of people have commented on how fast things are going together. I think this reflects on the number of hours we are putting in on the project. I worked 8am to 2am Saturday and  10am to 10:30 pm Sunday.  Monday I did a full day of work at NetBurner Then spent the evening organizing some of the electronics planning connectors etc.. I went to bed at the early hour of 10:30pm. Today I got up at 6:30 am and went into work to spend 2 hours building our control PCB’s under the surface mount microscope. I then worked till 1pm and took 1/2 day off to spend some time with my wife. (More on why later in the post) Then I worked from 7:00 pm to 11:30 making servo mounts. I will do it all again Wednesday. I’m a bit tired, but it feels good. For all of you who read the blog and are not working on some dream or project, turn off the TV and do it. It will feel better than anything you have ever done.

Budget

Last year we had some cash  set aside for the project, we used most of what was set aside. This year we are funding the project directly out of current income. Last year cost almost never figured into the project. If we needed a part or a tool we had it next day.This year we are much more cost aware. Things like building the SMT board myself instead of sending them to our prototype house to have them build them at $500 a pop.  Ordering the raw PCB’s with 5 day lead rather than 2 day etc…. Now in my primary day job we send a lot (more than a million $) of work to the PCB assembly house and I could call them up and say its a personal project and they would probably assemble them for free, but that is not how I do business. All business needs to be mutually beneficial and nobody makes money giving freebies. We have no budget issue with building two of this vehicle. The second vehicle we will lighten to the maximum extent possible. Based on our design info that may be enough to do the 180 second flight on 90% peroxide. It may not. If it is not we may seek sponsorship for the 180 second vehicle development. If anyone would like to associate their corporate image with our project please feel free to contact me.(  Paul At Romeo Alpha Sierra, Delta Oscar Charlie dot COM  Here to decode )

 

Life

I would not be remotely as capable as I am if was not for my father. He taught me to build things, work on things and not to be afraid of hard work.  He was a career Coast Guard Pilot and retired to start a bush airline in Alaska when I was 12. He earned the Air Medal twice for daring rescues and in 20+ years in aviation in the harshest weather in the world never had a Fatality under his command. If you’ve seen the Discovery channel shows about crab fishing in Alaska, that is where dad flew for the Coast Guard. He did two tours of duty in Kodiak and one in Annette Island. Unlike todays Coast guard where pilots fly either Helicopter or Aircraft he flew both the large flying boats  and the helicopter. When my dad was stationed in the lower 48 he designed built and raced small outboard hydro-planes. He called his boats Flying splinters, hence the name for the vehicles in this project “Burning splinter”. In any case my dad is 78 and loosing contact with reality. He is to the point where he can not live alone and needs assistance with daily living. My step mother is going on a business trip and vacation to Paris for 14 days and we are taking care of my dad while she is gone. We have done this for shorter periods before, but two weeks is going to be a challenge. That is why I took the afternoon off to go hang out with my wife, for the next two weeks we will get very little personal space. I also expect that progress on the project will slow, but not stop. My dad likes to sit in the garage and watch us work. We are getting used to being asked what it is we are building…every 60 seconds like clock work.  

Four Vanes done

Started at 10:00 am finished up at 10:15 pm. I made two new vane blanks on the Lathe, and played with feeds and speeds on the mill. Then I milled 4 good vanes. It takes about 1.5 hours each just for milling them down to thickness. Anything faster than that and they bend.

 

In anycase I have four good vanes and one actuator mount. Two of them were loose enough to press onto the bearings. Two required the freezer and heat gun approach.

Monday night I should finish the four actuator mounts and get it all put together. (I still hate stainless).

I hate Stainless...

Some notes on how I design things. Some people make detailed 3D cad models of their complete vehicle. I do some dimensioned drawings, but I don’t make them a complete detailed cad model. The drawing below was my layout for the Jet Vanes.

This drawing was done in Rhino to scale. but as a flat 2d drawing. When the vane mount got welded to the exit cone if was about 0.1875 too far down. This caused me to redo my vane bearing mounts and redo the jet vanes as the bearing is now 0.2” farther from the exit cone. 

Once I have a scale drawing of the parts I make a simple dimensioned drawing I can take out to the shop or use to generate CNC code for the lathe. I don’t have a good lathe CAM program so all the Lathe CNC code is generated by hand or by writing a program to generate the CAM file. The CAM generation on the mill is automated from the drawing.

This is the drawing for my new corrected vane. I got up this morning and went to two places, IMS to get more 316 stainless shaft to make vanes out of, and to Marshals Industrial hardware to get some more carbide end mills to cut the stainless. So after working from 8 am to 1:30 am I have the following:

The three parts on th left are not yet destroyed. All the parts on the right are toast in various ways. The four that look relatively complete are done to the original drawing and are now the wrong dimension. Some of the bad ones have the wrong bearing dimension (They are loose on the bearing), I had a problem in my hand crafted lathe code where I made 4 exact errors…. The other two are the result of milling problems, the new carbide bits I got today just aren’t lasting. MY last set that I ordered from MSC would do two vanes before they were dull, the ones I picked up today last for 1/2 of a vane.  So since I went through all my carbide tooling I though I’d try a big 3/4 TAIN coated HSS end mill, real slow…. The one in the middle left with the notch is the result of that experiment. The bit cut just fine … for awhile then it suddenly welded it self to the work piece and when I based the mill to recover it bent the vane. The three parts on the left are done with the lathe work (sort of) and now need milled. The one on the bottom left that looks like it was gnawed by a rabid squirrel is the result of trying to part off the  vane and having the parting tool die. I really should not be parting solid stainless on my Lathe its just not rigid enough, but I don’t have the shop space for the proper tool, a metal cutting horizontal band saw. I even tried the Armstrong method, I bought the highest quality hacksaw blades I could find at home depot and after two strokes the stainless removes all the teeth. 

 

Lastly the lathe makes miles of razor sharp stainless turnings, They get tangled with everything and cut you if you just look at them crooked.

 

 As a general rule I don’t wear gloves near machine tools, its a good way to loose your hand. So in the last 24 hours I’ve bled from 5 of my 10 fingers.

The vanes are bieng used in a hot oxygen stream so I need the maximum oxidation resistance, otherwise I’d use 303 stainless a lot easier to machine. Did I say I hate Stainless?  Hopefully today will go better…

 

 

Plumbing complete

The vehicle plumbing is complete. I should have the Jet vanes finished Saturday. That leaves wiring. We weighed the vehicle as is and its  96 lbs . We have less than 5 more pounds to add (not including payload) and we should be a full 25% under our target weight. We can meet our 90 second hover with an average achieved ISP of 79 seconds.

Without payload running 90% peroxide we should be able to hover for 160 seconds.

Feeling Blue

Best of Days Passed Hydro

Minimum Structural Hydro 1.2  1.2x 300 = 360 PSI, we went past 360. Design burst is more than 600 design SF 2.0 we can now start some actual testing, the vehicle will never be presurized with humans in the safety hazard zone. We will build a second vehicle with better weld prep and hydro that to a higher pressure.  for now we can do a lot of testing with tank pressure < 240 PSI.

Update...

Congratulations to Cal State Long beach/Garvey Space, (The team members overlap a lot so I’m not sure which group was the lead, the rocket I saw pictures of had decal for both) I heard  they successfully flew a Lox Methane rocket this weekend.   (I think this is the first ever) This adds to that groups firsts:

• First Flown composite Lox Tank.


• First flown aerospike


• First flown Lox Methane.

 

For Unreasonable Rocket we think we were able to repair the tank. We will do a new Hydro test on Monday night or Tuesday. We re-welded the entire seam with a lot more heat. In any case I’ve been investigating new tank concepts and I’ve found a tank concept that will be stunningly light for peroxide. We may work on this for the 180 second vehicle. 

I finished machining my first Jet vane and shaft out of billet stainless (I hate machining stainless) I’m going to try to finish a couple more tonight. The Lathe work is done on all four ,the mill work still needs done on three of them.

I hunted down the cause of my helicopter crash and resolved that. I had a gain constant off by a factor of 2 when switching from position hold mode to position  and altitude hold mode. I flew it again and it flies nicely, but the tail rotor started acting really flaky. It would drift all over the place and not hold heading. Something is wrong, but all my field diagnostics gave me no info. I’m a bit stumped. I’m tempted to give the computer direct tail rotor control and remove the tail rotor gyro using only the IMU for tail rotor control. Just Like Jack did a while ago…

Best of Times woorst of times..

Tonight we went from vehicle ready to wire…

To almost passing hydro test… For our operating pressure of 300 PSI the FAA minimum is 360 PSI, the sphere has a design burst of > 600 PSI, we got to some where between 350 and 370  we wanted 375 to 400. (We will never presurize in the presence of humans.)

Its clear we did not get enough penitration, the weld only went ~half way through the base metal. Very discouraging.

Quick Update...

The Landing Gear main legs are done after the first attempt did not work, the orings leaked and the retaining ring was not strong enough. We will get the gear brace mounts welded up on Tuesday, it shoul dbe sitting on it’s gear by mid week. We had hoped for a full vehicle static fire on Saturday, its looking unlikely.

Crashed the helicopter again, only very minor copter damage, but destroyed on of the expensifve LiPo battries. Went into a weird pitch and roll osscilation.  Probably need to do some gain tuning. broke one blade and destronyed the battery, otherwise undamaged.

Sphere vehicle rough rendering

There are a bunch of details missing such as braces for the motor,electronics boxes, jet vanes vents etc…. but it’s aproximatly right.

Autonomous Hover Video

Not produced to the best quality, but it shows the helicopter hovering,

both in manual altitude and full altitude hold modes..

 

Autonmous Hover

I just finished flying out an entire Trex battery pack in 3 axis autonomous position hold hover. (Altitude was still manual) I set the reference position landed, moved the helicopter and it returned to the commanded position from 10 yards away with displacements both north and east of target. Hover never seemed to deviate by more than 1.5m from center. At one point the hold position moved about 1m in a pronounced step, I have not analized the telemetry yet, but I assume this was a change in the GPS sats tracked. This was done with the Hemisphere GPS in 20Hz update mode, but without the differential corrections. I will attempt to acquire video to bring with me to space access. I’ll post telmetry details later tonight.  

More Pictures....

The whole assembly is upside down.

From Top of picture to bottom…. Motor (not yet welded together) Big stainless check valve, main valve, tank(100% welded) plastic bucket. We will provide some pictures of the tanks in process as our welder Bob took some pictures, but I don’t have them yet.

Detail shot of the gear mount. (Upside down) 

Detail shot of the Tank Top…

 

So far the tank is about 5% over the “Spread sheet” target weight and the motor is 50% under the spread sheet SWAG, In total all parts we can weigh are comming in under the target weight.

The motor exit cone needs to be shortened a bit and the main chamber will shrink as we have a really parinoid L*. We are missing one small fitting for the Catalyist injector fittings or the whole motor would get welded together today. The local indusrtial hardware store is usually open on Saturday, but they closed for Easter.

Data Results

We went back out and reran the test after the purple nighmare.

Here is the pressure data from the decomposition test. Note that the chamber pressure dropped off more than the feed presure did this makes me think the excess permangnate at startup had a positive effect and we would benifit from from some kind of screen in the chamber to hold the reactant products longer. Note how the feed pressure drops off rapidly when the peroxide runs out.

 

Here is the data with thermocouple voltage data added. One channel did not work at all and the data is very puzzeling. TC1 (not shown) is at the exit with TC2,TC3,TC4 getting closer to the Injector end. Either I have my wireing notes wrong (possible) or I don’t understand the data.Why would the thermocouple in the middle be lower than the one on the ends?I have not calibrated the thermocouple data, its displaying scaled RAW A/D counts. From the noise its clear I need to work on my TC amplifer some more.

Here is the video from the test series

 

 

The Purple Menace strikes back.

A quick update, we’ll post videos and more info in a couple of days. We went out to FAR to work on the site and run a quick repeat of our decompoisition test. When we ran it a flxible stainless line from the  permangenate tank to the motor failed at the fitting spraying permangenate everywhere. We had gotten a bit lazy and did not remove the tools generator etc.. from the vicinity of the test stand. SO everything involved with the test is covered in fine purple goo. We only used 1 liter of permangenate ,but 1 liter covers a truely amazing amount of area. The leak was at about 300 PSI so we covered  everything in a 35 foot radius with purple goo.  I can’t find the reference, but somewhere I’ve seen a dilution ratio of 10000:1 specified for making the purple go away.I can personally vouch for that number. I can also vouch for the warning one of the Arocket chemists gave me that vitamin C solution is exothermic with concentrated permangenate. A Vitamin C and  soaked shop rag used to wipe down  permangnate splash will end up smoking.

Progress...

This morning I had a conference call with the FAA to talk about getting started again.  With the rapid progress we are making on the simple vehicle there is a very real possibility that the ability to get a burn time waiver will become a limiting issue. So I need to go back into paperwork mode, the most fun part of the project!

Based on some feedback from John Carmack and some personal experiences trying to get Large fittings to seal we are switching to sanitary fittings for all of our large plumbing. We have always wanted to use a butterfly valve for better throttleing and less hysteresis, this is hard to do with lox as no seal material is soft at Lox temps. With peroxide its a bit easier, we found a 1 inch butterfly valve with built in sanitary connections and hydro tested it to 500 PSI. It held fine and operated correctly. Its nominal commercial rating is 150PSI, we are going to run it to 300 PSI. My son designed and machined a two peice aluminum housing to hold the valve and connect one of our servos to it.

Its a fast 1” valve.

 

How come we spend so much time on valves? Here is the dual igniter valve we made last year…

 

This weekend we are going out to FAR to rerun the L* test with sodium permangenate. We are also going to do a bunch of site improvement work, trenching, running power and data wires and boring the big hole to put the foundatiuon in for our tether crane.

 

Stunning Rocket news: at 8:10 PM everything is packed and I might get a full nights sleep before a test!

Helicopter Tanks and Shuttle

HelicopterI’ve got the helicopter flying in attitude hold more, but I have not yet turned on the postion hold software. I want to review the data from an atitude hold flight before turning on the position hold. So I went out and flew the helicopter again today. Data records fine at home, it records fine according to the lights on the recording unit, alas when I get home and look at the SD card no data. Arghhhhh….

Tanks We did a lot of prep work on the tanks today, we figured out what brackets, fittings etc… need to be welded on. I also machined some Aluminum sanitary fittings for the main propellant line. My  mcMaster sanitary parts arrive on Monday so I’ll see how well I did with the aluminum ones on Monday. One of the hemispheres has a stress crack that goes all the way through. I hope this is not an omen for the whole set of 6. I think I can probably stop drill the cracks, grind them out and weld patches over them, but its less than ideal. We’ll save that hemisphere for last.

Shuttle One of my long term really want do to items is to watch a shuttle launch. I’ve seen it land 3 times (including the very first time), I’ve never seen it launch. Tuesdays launch will be a night time launch and should be quite spectacular. I came real close to hopping on southwest and flying out to florida to see the launch. I would have cost me $800 two days of works work and at least one day of Unreaosnable work and in the end I decided that I really want the time to work on Unreasonable. We are so close to having every thing come together for the new 90 second vehicle. So I’ll try to be less impulsive and plan ahead to go see the next launch.

Parts

The new 1” (or possibly 3/4”) valve mechanics.

The baffels for the new tanks… they still need to be trimed, fitted and welded.

Parts for the potential off the shelf monoprop chamber only welding required… (Will probably up the base tube size for a shorter chamber.)

 

Data and Plans

Based on a lot of discussion with the chemists on Arocket its clear that the potasium catalyst was about 1/7th as active as the sodium catalyst I’d designed for. So we need to rerun the test when we get our sodium permangenate. We have it on order from two different sources. I finally reduced the data from my test and I got zero thermocouple data. I need to work on that. We hope to rerun the test on the 14^th.

Here is that data I did get.

Several things to note. first off my pressure regulator is not healthy. Its hitting the correct final pressure, but it is not happy doing so. Second according to the CV calcs I did the 1/2 inch valve should have about 10 PSI drop at full flow, it clealry had 150 PSI of drop. This could be because chamber pressure did not come up due to incomplete decomposition, but in that case I would have expected a larger injector drop due to too high of flow. Toward this end I spent the last two nights fabricating a fast 1” ball valve controller, I’m waiting for one more McMaster part and I’ll test it Thursday night. 

We are currently fleshing out the details of our 90 second test vehicle. We made baffles and parts for welding the tanks together. I’ll provide pictures when the tank starts going together. The last parts should be back from the Water Jet Cutters Friday. We are going to use AN fittings for all the plumbing smaller than 3/4 and probably sanitary fittings for the larger plumbing.  We have one area where the two Pauls do not yet agree, we can’t decide if we are going to use attitude thrustors or jet vanes. For the monoprop the jetvanes are clearly a win, but our longer term plans include making the vehicle a bi/tri prop by adding fuel to the peroxide and getting more performance. The bi/triprop  is a bit warm for jetvanes. It probably means we need to use some kind of exotic refrectory metal or ceramic. The bi/tri prop is the  current path to the 180 second prize.

For the Monoprop the safety system will be easy, we will add one small normally closed  valve to the liquid catalyst. As you can see in the video the thrust stops abruptly when the catalyst is all gone. (You can also see this in the chamber pressure trace above)  The bi/tri prop is more problematic as one might expect the biprop to keep going even if you turn off the catalyst.  If all goes well we expect a compete monoprop vehicle in about 6 weeks. We have all the long lead parts in hand. The current design is really really simple

I’ve glossed over a whole bunch of work… cat pack research, small thrustor chambers, learning about peroxide chemistry,high temperature ball bearings,  big servos, off the shelf source  thrust chambers, work on the helicopter, etc.. etc…

I’ll present the details of the 90 second monoprop vehicle design at Space Access. We will be at Space Access for all three days.If you are a space fanatic, and enjoy hanging out with three sigma nerds you can’t beat space access. 

Testing new Blogtools

To date I’ve been doing all my blogging with the blogger online tool. It is really limited, today I’m trying a desktop blogging tool. I’m hoping it will make things a little easier.

This picture was taken by Ben Brockert, one of the Masten guys that came out to watch the test. As he says ("Where's Waldo" bonus: find Paul's foot) Also notice the wind swept hair and the flapping tee shirt. It was REALLLY blowing.

Here is the You tube video embedded in the blog. The tool I’m trying is blogjet.

The Purple Menace

Saturday we went out to FAR and ran a test to determine Peroxide decomposition L* for a liquid catalyst. We were unable to get Sodium Permanganate for this test so we ran it with Potassium Permanganate. This results in about 1/4 the amount of effective catalyst. The end result is that we did not get full decomposition. The peroxide was still cloudy at the end of the tube. We did however fully check out a new test stand and data collection. All the parts worked correctly. A lot of people have told us that Permanganate makes an insane purple mess. Part of this test was to determine if we could handle this "mess". Thanks to a suggestion on Arrocket we mixed up a saturated solution of Vitamin C powder and that cuts the purple menace, making cleanup a non event.In the test setup we had insufficient permanganate so 100% of it was reacted in the engine leaving the engine perfectly clean. The only purple goo was from filling the cat tank.

The Last time I was out at FAR it was really pleasant. Nice lite breeze, moderate temperatures in the liow 70's and generally jerust a pleasant environment. So I convinced my desert hating wife to come with me this time. This must have angered the mojave deity as the wind was blowing so hard it felt like you were being sandblasted. The wind was blowing so hard that 2.5 GAL distilled water jugs 2/3 full were blowing over. It actually complicated the peroxide handeling, as we were in a blowing catalyst blizzard. It also made the personal protective gear hard, as the wind would blow a full face shield off in an instant. Also when you get peroxide on you it stings/burns, the blowing sand/rocks/boulders also sting. We were forever walking up to each other and saying any white spots on my face? The answer was always no, so we had no peroxide issues, but the sand was really unpleasant. There was a discussion of what was worse the wind or the 125degree heat we've seen on the site. Most preferred the heat, then John, who lives near FAR, said why do you think you would not have both? That pretty much ended the what if discussions involving mojave weather.


I've posted a a quick youtube video of the test. As a side note this test went from a concept to a test including assembling a test stand, fabricating a test motor and custom thermocouple electronics in 7 or 8 days.