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Please Don't Steal My Idea (just kidding... kind of)

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Jersey Devil

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Hey everyone been a while since I've posted because work and school keep me busier than I care to be, but while sitting through classes and thinking of anything BUT what's going on in class I had an idea that I need some help completely figuring out...

What if I built a rocket that looked like your basic body tube, fins, and nosecone, but when it reaches apogee the fins rotate 90 degrees and become helicopter blades??? The only way I could think of doing it would be to have the fin attached to a wooden dowel that ran through a small tube like a launch lug that runs through the BT and has a small weight on the other end that would cause the fin to rotate once the rocket begins to arc over but then you'd need to figure out how to get it to stop in the right position and stay there during descent.

This may be more complicated than it needs to be, but I've built 35 kits and I am working on getting away from the basic BT, nosecone, and fins because it is just waaay to boring. So any thoughts on this matter will be greatly appreciated and I suppose ridicule would be semi-appreciated because every once in a while you need someone to tell you it's impossible to get you working to prove them wrong. Can't wait to hear any input, and thanks in advance!

JD from SJ:cool:
 

JStarStar

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And, something similar at least in configuration to the SpaceShip One X-Prize vehicle. Fin surfaces rotate to maximize drag for reentry/descent.

Art imitates life... ;)


I'd love to find out if one of the Scaled Composites designers at one time in his childhood, built a Gyroc... ;)



And... "more complicated than it needs to be??" :D :D :D Of course, that's why you're doing it!! :D :D
 

wwattles

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Friend here in San Diego did one that sounds like what you're describing, but he completely ejected the motors. They extended about 1/2" from the rear of the rocket, and the fins had a little dowel that stuck out and held the fins in a "launch" position. When the motors ejected, the fins were no longer held in a straight position, and a rubber band pulled them up to a 80-degree position. It wasn't the entire fin, by the way, it was only the last half of them. The front half is what the fins were hinged on, and what they braced against when the rubber bands pulled them up.

WW
 

powderburner

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If you use 'normal' rocket-sized fins, or even large fins, I am afraid they will not slow your rocket very much even if you can think of a pivot/actuation mechanism.

As someone pointed out, there is a similar system built into the old Estes Gyroc design. You ought to look this one up and try building a copy. As big as those fins are, and as light as the Gyroc is in descent mode (empty motor casing gone at ejection), it still comes down pretty fast.

If you look at the helicopter duration designs, they all have high aspect ratio blades (the ratio of span-to-chord is high). They achieve low descent rates but the rotors have to be stored internally or conformally to avoid being torn off during boost. If you want to use long slender fins/rotors in your new design, you will have to store them in a similar fashion for the boost phase.

Sorry to sound so discouraging, but I expect you will either have unacceptably high rate of descent or else your design will drift toward another helicopter?
 
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