DynaSoar
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- Mar 14, 2004
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This rocket isn't swing stable. Several swing tests with C11 through E engines installed show it to be neutral stable at best. If there's software able to model it, I haven't seen it.
It's 16" of 24mm tube with an engine hook, 2" * 1/8" lug, Apogee plastic nose and 4 itty bitty fins. Recovery is a simple kevlar cord glued inside, and a 3 foot mylar streamer, with an elastic loop on the nose for shock absorbtion.
The fins are 1/8" basswood, 1" high by 1.25" wide. But the fins are beveled at 30 degrees on one side on the leading edge, and the other side on the trailing and outer edges.
Flight tests show it to do exactly what the fins dictate -- it spins like mad. White on one side and black on the other, it's a grey blur in flight. It gives good straight flights. They're so straight, and the fins are so small, that there's not even a flutter sound. It just drills itself straight up at at least 10 revs per second. No weathercocking noticed coming off a 4 foot rod.
Not the sort of thing to be test flying at a group launch. Technically it's probably against rules until it's test flown because it can't be shown to be stable should an RSO ask. But this one's tested now, and it's passed fine.
The next version will be identical, except the fins will be only half an inch high. At that point they'll be more a set of vanes than fins. The new model should be at least as stable as this one, if not more so, because there'll be only half as much fin weight at the tail (CG forward), but every bit as much spin.
It's 16" of 24mm tube with an engine hook, 2" * 1/8" lug, Apogee plastic nose and 4 itty bitty fins. Recovery is a simple kevlar cord glued inside, and a 3 foot mylar streamer, with an elastic loop on the nose for shock absorbtion.
The fins are 1/8" basswood, 1" high by 1.25" wide. But the fins are beveled at 30 degrees on one side on the leading edge, and the other side on the trailing and outer edges.
Flight tests show it to do exactly what the fins dictate -- it spins like mad. White on one side and black on the other, it's a grey blur in flight. It gives good straight flights. They're so straight, and the fins are so small, that there's not even a flutter sound. It just drills itself straight up at at least 10 revs per second. No weathercocking noticed coming off a 4 foot rod.
Not the sort of thing to be test flying at a group launch. Technically it's probably against rules until it's test flown because it can't be shown to be stable should an RSO ask. But this one's tested now, and it's passed fine.
The next version will be identical, except the fins will be only half an inch high. At that point they'll be more a set of vanes than fins. The new model should be at least as stable as this one, if not more so, because there'll be only half as much fin weight at the tail (CG forward), but every bit as much spin.