Balls 31 two-stage to 50K attempt

[JEtgen]

"Seeking Clarity" (that's the rocket's name)

Our second day at Balls was consumed with trying a 4 inch to 2 inch 2 stage project that sims to just over 50K ft AGL.

Long story short, Staging is tricky, and we didn't get sustainer ignition.

The booster was built from Wildman FG 4 inch tubing, min diameter, including the Wm 4 -to - 2 transition kit. Motor was a 4 grain 98 (25 inches of propellant) research motor, basically a full "M". Sustainer was a 54mm min diameter FG rocket with 2 soller composites carbon sleeves laid-up on top of the FG for extra strength. Sustainer motor was a Loki L1040.

I designed my own head-end ignition setup using Loki's extended 54mm forward bulkhead.

here's a pic of the booster:



And here's one of the sustainer's tail end with the staging electronics that go on top of the Loki 54-2800 motor and the head-end igniter setup. I just used hi-temp epoxy to replace the smoke grain with the igniter leads glued in. Igniter was an ematch with Quickburst Procast and a pyrodex pellet for good measure. Oh, I did ground test that setup with a research 54 that I built. So I was confident that wasn't too little or too much. Actually tested it at 9000 ft MSL altitude in Colorado just to make sure the thin air wouldn't be an issue. Planned ignition in flight would have been between 10,000 and 13,000, so a close enough test I assumed.



here she is on the pad, with Jim Jarvis and Paul Snow helping and keeping me from doing anything stupid.



And here she goes... Note the fly-away rail guides from additive aerospace are just flying off...



Here she is right after booster burn-out and separation... Big thanks to my friend Joe Dellinger who joined Tripoli just so he could come to Balls and help document Jenni and my projects. He was really good at catching pictures with his camera work. Speed at this point was Mach 1.4, so he really has a good eye to track that thing.




She was programmed for a 10-second coast (8 seconds delay and a couple seconds to come up to pressure), unfortunately the sustainer igniter never fired, despite being well within all the criteria for ignition. We still don't know why. We will have to ask the Altus folks why, but our staging track-record has been so bad with the easy-mega (3/10), that I think we are going to try the BlueRaven next. I like the Telemega a lot and it is my primarly flight computer for recovery and telemetry. But we seem to be "snake-bit" when it comes to staging.

Worse still, the rocketman main chute in the sustainer "disintegrated" (Yeah just totally blew up) on sustainer main deploy and the sustainer came in with no main flat onto the playa and destroyed the nose-cone and cracked the sustainer airframe just above the staging electronics bay. So even though I had a second load for the booster, we weren't able to try again. Not too happy with the rocketman chute! Well, it's gone anyway. The accelerometer data shows only a 20G "spike" on main deploy. I suspect we received a defective chute.

On Sunday, we did fly a "lame" 2 stage (CTI-K600 to CTI J94) in our test 2-stage rocket "Spank the Brat". We basically took all the safeties (other than tilt limit) off the easy-mega, so this flight was a complete success.


The staging program for this small flight was just check motor 1 burnout, tilt <20 degrees, 3 second delay, no other criteria.

For the big attempt above, I set a 2000 ft min altitude and closed the "window" for ignition at 20 seconds. Somehow those criteria locked out the sustainer ignition, even though there was no reason from the data for that to have been the case. Booster came very close to sims and tilt was <10 degrees till >17 seconds (corrected, when I posted last nite I was not looking at the actual data. The data is now in a picture in a reply) into the flight. Oh well. We will try again next year!

 

[manixFan]

It’s great being out at BALLS and watching fellow Texans fly ambitious flights. Makes me realize I need to up my game. You might consider ’Spank the Brat’ lame, but I thought it was great – any successful 2-stage is a great flight in my book.

Thanks for sharing your head-end ignition setup as well, always good to learn more about how successful flights worked.


Tony

 

[cbrarick]

the photo you have of separation shows a lot of tilt - could this have been the problem? Do you have the data from the altimeter, along with the settings?

 

[JEtgen]

Here's the tilt data from the easy mega on board the sustainer. Tilt was less than 10 degrees out to about 18 seconds and under the 25 degree limit that we set until about 27 seconds into flight. The booster motor had a burn time of about 3.5 seconds. The apparent tilt in the picture is partly due to the perspective the cameraman has at that point in flight. Look at how much the rockets are foreshortened...

Here's the setup for the staging...



And here is the height data out to about 20 seconds.



As I had simmed, the 2000 ft height criteria should have been met right about MECO and would correspond to a nominal boost. So then we should see the ignition / activation of Pyro channel A at about 11.5 seconds, right about at 10K AGL, again, exactly as I simmed. But, no pyro channel A event/ indication. Just plain refused to fire. This has happened to us in one guise or another 7/10 attempts. We can find plausible reasons for 2 of those. One was a premature MECO detection which fired a separation charge while main was still running causing the booster to collide with the sustainer (our very first attempt). A more recent attempt this summer at a Tripoli Colorado launch was due to a defective lipo battery (that was brand new) that would not hold voltage above 3.6 volts and there is logic in the Altus products to not fire aux channels if voltage is below something like 3.7 volts. So we knew to religiously check the battery voltage before flight, and even do an extended ground test of any battery that was going to power a critical flight function a couple of days before the flight.

Still a mystery I think...

 

[kjhambrick]

John --

Your tilt data sure looks like you had a smooth, stable boost.

Sorry about the computer glitch.

Next time !

Thanks for posting !!

-- kjh