Saturday, March 7, 2009

Launch Report #26

It was 60° F out today, and they snow was all melted - how could I not go fly rockets, especially with Mandachan available for an audience?

First came the WAC-Corporal on a 1/2A3-4T. It boosted straightish but slightly unstable to about 200 feet. The nose cone came off but not the streamer, so it came a bit fast but undamaged. Failure of recovery devices was pretty common today.

Second was the maiden flight of the Nuclear Mosquito on a B6-4. It's a great motor for it, although a C6-5 would of course be better. The chute melted abit (it's still usable, though) and didn't deploy, but there was no damage other than a few grass stains.

Third was the repaired SpaceShipOne on a B6-2, the first time I flew it on less than a C. It flew straight with maybe 4 complete rolls before ejection, but the chute only half deployed and it came down a hair fast. One boom shattered despite the soft ground - it snapped at the aft end of the main wing-fins, then split lengthwise. I repaired it with superglue and wood glue, but unless it gets perfect deployments it'll have one more flight, maybe 2, before it retires. I'll probably use a D21-4 composite motor to give it a nice sendout. Either that, or I gotta start using larger chutes, and we all know how that went....

Fourth was the Astron Invader on the third B6-2 in a row. It looped twice near ground level, then continued upwards to about 200 feet before ejecting. It glided - upsde down - for about 300 linear feet, maybe 15 to 20 seconds. This is a great motor for it - A8-3s and B6-4s have too long of delays, and with C6-3s it's unstable for most of its flight, while with the B6-2 it becomes stable within half a second and flies fairly well.

Next came the Orbital Transport on a C6-3. This is the only motor I'll use with it normally; it boosted high and fast but with a nasty case of pitch-roll coupling, where the period of it spinning matches the period of its back-and-forth wobbling and it spins conically. It stayed in control, though, and ejected just past apogee. The booster's chute failed to deploy, but it landed safely with no damage. The glider glided for at least 400 linear feet in maybe 30 seconds; it flipped, circled, and did a few mild aerobatics in the light wind before flipping over at landing and snapping off the attachment dowel. An easy fix. Despite the pitch-roll coupling, it was a cool flight and 30 seconds is a respectable C glide time, especially with a complex, heavy booster and a glider designed for looks, not glide ratio. I had very good luck with gliders today.

Next came an ungodly monster: Vampire (D12-0) staged to Hi (C6-0) staged to Frankenstein (C6-7). It was designed to go to a half mile high, eject a full load of tracking powder, and sacrifice Frankenstein to the rocket gods forever. However, with the heavy 3-motor combination, a fairly short rocket, and the smallish fins of Vampire, it wasn't quite stable with all 3 stages. It went sideways at about a 25° angle from the horizon. The Vampire dropped off about 250 feet from the pad about 150 feet in the air; the C6-0 igited and it became stable. the Vampire dropped safely to the ground, It was lucky. The stable but awry and falling rocket simply could not maintain its heading under the thrust of the C6; it crashed audibly into a football field (fortunately empty) about 450 feet away from the pad. This is the scene:

A close-up of the impact site. The purple fins of Frankenstein are plastic and slide safely out of their holder; the balsa fins of Hi do not.

The Hi booster was a total loss. The nose cone (found 120 feet away from the impact site), fin unit, shock cord, and fin unit of Frankenstein are intact and will fly again with the same purpose - and bigger fins. The C6-7 did not ignite and will fly again in Frankenstein 2. Due to the hard impact (CATO risk) and the clay cap being partially broken, I won't fly it in anything else.

Finally, I flew the WAC Corporal again on an A3-4T. It was less stable this time; it arced over significantly. The motor was ejected; the nose cone came barely off but the streamer stayed in and it core-sampled. No serious damage; it'll fly again.

So - two sucessful gliders, 3 chute failures, 2 streamer failures, and one epic crash. I'm up to 526.36 Ns (64.5% I), with 111 motors used on 96 flights on 44 different rockets and boosters. 4.74Ns (89.7% B) per motor and 5.48Ns (9.7% C) per flight. I can't believe I'm already 2/3 of the way to a J motor.

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