At 11:33 AM 11/14/2002 -0800, Randall Clague wrote:
On Thu, 14 Nov 2002 02:27:00 -0800, Pierce Nichols <[EMAIL PROTECTED]> wrote:>just for Spike, I can cut the length down to 12'. It also looks like I'm >going to have to go with a form that uses fly-away rail buttons of some >kind -- I just can't seem to get the shoe idea to work within a decent mass >and dollar budget. How big would these rail buttons be? If we're talking about delrin buttons of a size that can't hurt someone even falling at terminal velocity, then fly-aways are OK. Not preferred, but OK.
They will probably be a bit larger, but on the same order of magnitude. One of the popular solutions among the HPR crowd is a flexible band wrapped around the rocket and a lug that looks like the two halves of a hinge. On the rail, the two halves are held together by the rail; when the rocket clears the rail, the band straightens out and drops away. The surface area to weight ratio is so large that it tumbles harmlessly. In any case, I'm not too worried about falling rail lugs -- we have everyone under overhead protection anyway and they aren't going to go far.
Adjust it manually fairly simply *and* safely *and* quickly and easily.
Of course. A crank & ball screw arrangement would be ideal, but more expensive. I was also thinking of cables with turnbuckles for adjustment, and a come-along for erection.
Yes we do. Weathercocking == high horizontal velocity == damaged parachute.
Then we should also look into ways to alleviate snatch forces at deployment. Like getting Dave W and your brother the rigger together. High horizontal deployment speeds do *NOT* necessarily mean damaged parachutes. If NASA can safely deploy parachutes at supersonic speeds, then we can figure out how to do it at middling subsonic speeds.
We can't have it both ways. If we don't want to risk shredding the parachute, and we don't the thing to land a long way off, then we can't launch in the kind of wind we've been launching in. I'm in favor of compensating for the wind and four wheeling across the desert for recovery.
I'm not thrilled about driving cross country over the desert, due to the environmental consequences. The tracks I left in April were still clearly visible, even after six months and the rains in the preceding days. There are also the fence lines that might have to be crossed -- when we get to one, the recovery shifts to foot.
Another alternative, which we're going to have to do for Spike so we might as well test it in KISS, is dual deployment.
Dual deployment actually has much less of a problem with high speed deployment than standard deployment, since you can make the drogue a great deal heavier and sturdier than you can make the main chute.
-p
Mars or Bust!
www.marssociety.com
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