rict
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- Oct 21, 2004
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I'm trying to design a min dia 29mm rocket for the altitude record for our local club, and I was trying to choose a streamer/small chute for recovery (I'm in the design stage). This rocket will have both an altimeter for recording apogee and firing the apogee charge, and a radio tracker transmitter.
For a safe recovery of this size/weight, RockSim calls for an 12-16" dia chute. While I've had success with chute ejection at this size, I've also had chutes that either never ejected, or ejected correctly but didn't open properly (from being compacted in the body tube). I was thinking about a standard streamer, but then I thought about this:
What about an ejection charge that fires at apogee, splits the rocket into two halves that each have about equal weight and drag, connected by very long (maybe 12 ft.) shock cord that is actually a 1" wide ribbon? Now the two parts of my rocket are falling about level horizontally with whatever amount of drag that creates, with 144 sq inches of ribbon connecting them also creating drag. Compare this with 113 sq inches of surface for the 12" chute...
I've done no drogue, dual deployment recovery with my larger rockets (4 inch dia and larger) before, and I've seen these rockets falling fairly slow (for their weight) in this configuration before reaching the main deployment altitude with just regular kevlar shock cord connecting the two halves. This would just be taking this to an extreme in "designing" the shock cord for maximum drag.
I'd have to find a "ribbon" of some kind of material that is strong enough, wide enough, and thin enough for this to work. Anyone done this?
Ric T.
For a safe recovery of this size/weight, RockSim calls for an 12-16" dia chute. While I've had success with chute ejection at this size, I've also had chutes that either never ejected, or ejected correctly but didn't open properly (from being compacted in the body tube). I was thinking about a standard streamer, but then I thought about this:
What about an ejection charge that fires at apogee, splits the rocket into two halves that each have about equal weight and drag, connected by very long (maybe 12 ft.) shock cord that is actually a 1" wide ribbon? Now the two parts of my rocket are falling about level horizontally with whatever amount of drag that creates, with 144 sq inches of ribbon connecting them also creating drag. Compare this with 113 sq inches of surface for the 12" chute...
I've done no drogue, dual deployment recovery with my larger rockets (4 inch dia and larger) before, and I've seen these rockets falling fairly slow (for their weight) in this configuration before reaching the main deployment altitude with just regular kevlar shock cord connecting the two halves. This would just be taking this to an extreme in "designing" the shock cord for maximum drag.
I'd have to find a "ribbon" of some kind of material that is strong enough, wide enough, and thin enough for this to work. Anyone done this?
Ric T.