Well, that didn't work out very well
Chatted this up at the sport range a bit Friday, got a few tips. Tried a couple test flights in a big clunky sport model that I thought would have a similar flight profile to the pretty nice looking/detailed contest model I'd built, based upon a mediocre boilerplate flight that didn't get high enough to trigger launch detect in an altimeter. First test--low and slow (I'm talking 50 foot apogee), but no deploy. I figured it wasn't triggering the 2g/half second launch detect on the timer, though I'd think it's hard to do that while clearing the rod. Put same model up on twice the impulse, and the charge fired but not enough to blow open the BT-80 tube. No big deal--I'd use more powder and switch to slightly more powerful motors for the contest model.
Contest model turned out to boogie off the pad, getting up to 300 feet or so very quickly. Came crashing down, no deply, model destroyed. Post mortem observations and assessment:
1) Model certainly exceeded 2g for more than half a second. No doubt whatsoever. The g-switch could have been faked out, though. I mounted it somewhat loosely in a BT-50 stuffer tube (padding for and aft to prevent damage). Still, if the switch slid back I can see how the G-switch could have been faked out. Shouldn't have been much of an impact, though--there's a solid bulkhead that would have prevented a slide of more than an inch.
2) Inside of body tube where the charge was appears to be clean--no signs of burning, smoke, etc.
3) plug-in connector for xmas bulb charge shows signs of charring
4) Crash site--didn't see the heat shrink tubing holding the charge laying around, but didn't have time to look too closely. Definitely no longer on the bulb base, and it was on there pretty good.
In terms of figuring out what went wrong/what to do differently, I'm really stewing over not knowing what happened.
- timer slid around, loosened wire/faked out G-switch (need to mount on board)
- xmas bulb failed (timer beeped continuity check OK)
- Powder slipped out of sleeve (unlikely since sleeve no longer attached)
I think I'm going to build another copy of the model, but this time will design in the electronics rather than slide a timer in as an afterthought. Definitely mount on a board which ends in a bulkhead, with timer aft and feeding charge through a hole in the bulkhead to the forward-mounted chute. This is opposite of what I did the first time.