6/13/11

June Launch Report <-- Boring Title But VERY Interesting Article

No matter what safety precautions you take, at the end of the day getting beaned on the noggin with an Aerotech Sumo coming in ballistic at a couple hundred feet per second is bad for your health. Just saying.

Despite that little incident (the victim is doing well now, but everyone was freaked out of their breeches at the time), the launch was a smashing success! (No pun intended).

First off, there was an M motor with three outboard J's that were going to airstart. The M cato'd.

Then there was a big Hypertek M motor that would fill with nitrous oxide but was having issues with the ignition system. No joy there.

Then there was my L2 certification attempt. We won't even talk about that.

Just kidding, we will. So I passed the test, no sweat. I had studied for it several times before but never got around to taking it for one reason or another. Then I got my rocket ready to fly: Stinger on a J285. I'm so brilliant. I certify L1 on an I285 which is a huge I, and certify L2 on a J285 which is a baby J. That way I can use the same rocket, same casing, same average thrust... It's amazing they even let you do it that way.

But then it came down to launch time. Despite my 4-caliber stability margin, the rocket had issues on the ascent. I'm still analyzing the video to figure out what went wrong, and I'll post it on YouTube later for you all to analyze as well. But something fishy happened. It corkscrewed a little and increased drag so much that what should have been a 5000' flight turned out to be a 1500' flight. Therefore, a 15 second delay for the motor eject was waaaay too long. The main was set to deploy at 500, but I'm not sure which deployed first, the drogue or the main. I guess I will have to look at the video and figure all these things out. But the point is that it was going way too fast when it finally ejected, and the rocket separated and I failed my certification.

Oh well.

There were some other cool things about the launch, like an L1500, and a minimum diameter H399. Mach 1.25 on the H399! But I'm too lazy to cover every launch in great detail, and besides, reading about it just isn't the same thing as actually being there.

I'm going to build a new rocket for July, so stay tuned for some build pics.

3 comments:

R2K said...

Better luck next time! Ive had even worse luck with level 2 (I still don't have it now 11 years after first certifying level 1.)

Test was no problem, and the first flight was great... but on recovery of the first flight the damn nosecone was missing!

Very annoying (but worth it as the flight was sick, 54mm rocket on a J motor really moves.) After getting mad, and modifying the rocket to screw the nosecone in with two huge screws (overkill) I flew it again. Well tried to; the darn CTI motor had a cato and the rocket was gently tossed off the pad. Minor damage, but really this marked the start of a long break from HPR for me, about three years.

DTH Rocket said...

Yeah... my nose cone might have gone missing but at the last minute I remembered it and taped it down. Vent holes might also help, but I don't like to put holes in my rocket if I can help it.

The funny thing about CTI motors. They're so easy to put together but they still fail quite frequently. I like to open up the reload and inspect the grains themselves. After my first experience with these motors I don't want to take any chances.

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