Manoel Victor
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- Oct 31, 2019
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How to calculate the size of the spin hole?
Typically a spill hole is 10% the diameter or 1% the surface area. This number is tricky, too big and you loose drag, too small and the parachute will be unstable.
Typically a spill hole is 10% the diameter or 1% the surface area. This number is tricky, too big and you loose drag, too small and the parachute will be unstable.
Thanks very much!I've seen chutes with spill holes and considerably higher Cd than chutes with no spill hole at all. Examples are Fruity Chutes Iris (claimed Cd of 2.2) and BAMA Aero-spherical (claimed Cd of 2.0). Compared to Cd of 0.7 to 0.8 of average no spill hole hexagon chute. BAMA Tesla has a huge spill hole, and claimed Cd of 0.99. Fruity Chutes Elliptical claims Cd of 1.5 to 1.6. I'm not an expert, far from it. I know little to nothing about chute design. However, surely, there is much more that affects drag than the size of spill hole.
Above examples are from the two chute designers/manufacturers I bought chutes from in the past. I'm sure there are many more other examples.
P.S.
I know you make very fine chutes too, and I've seen them flown at several of local launches. It's just that I'm not as familiar with your chutes as with the other examples I mentioned.
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