1st winner of the Sikorsky human-powered copter competition

[Lagmonster]

According to CBC (and the video is cool as hell), someone finally took home the prize in Sikorsky's Human_Powered Helicopter competition, by designing something that looks like it could only ever be piloted indoors, with no breeze, and people with wires guiding its direction.

But it is still a cool engineering feat.

http://www.cbc.ca/news/technology/story ... prize.html

[Sea Skimmer]

Looks like it could only be piloted in doors? Of course! Its not a joke that for more then a decade man very well educated people though the requirements to win were so demanding as to be physically impossible. Its an amazing accomplishment that it was finally done. Just making a human powered helicopter isn't so hard, but as the article says prize required hovering in a fixed 10x10m area of space for a set amount of time, and every previous design that could fly was not stable enough to do so.

[Simon_Jester]

Helicopters are inherently pretty unstable; as wags have put it, "God did not mean for them to fly." There's a reason that real helicopters use a tail rotor, when airplanes don't need any such thing. And once a helicopter starts to tip over, the force that's holding it up in the air also starts to tip over, which strikes me as a recipe for a positive feedback loop.

[GrandMasterTerwynn]

Helicopters are inherently pretty unstable; as wags have put it, "God did not mean for them to fly." There's a reason that real helicopters use a tail rotor, when airplanes don't need any such thing. And once a helicopter starts to tip over, the force that's holding it up in the air also starts to tip over, which strikes me as a recipe for a positive feedback loop.

Which is why this particular human-powered helicopter is a gigantic quadcopter made from toothpicks. Having four main rotors spread out increases stability by putting the lifting forces out at the ends of those long arms (the people holding on to its tethers certainly helps too.)

[Simon_Jester]

Yes- I was just sketching out the general nature of the problem, and why a human-powered airplane (or any airplane) is much easier than a human-powered helicopter (or any helicopter).

Airplanes, with a handful of exceptions in the fighter jet class, are intrinsically stable. If you start with the controls at a neutral or nearly neutral setting, and you take your hands off the controls, they will tend to fly in a straight line without crashing, at least for a good long while.

Helicopters are not like that, at least not in general.

[cosmicalstorm]

Awesome. As a child reading sci-fi I loved the part in Rendezvouz With Rama where one of the members on the mission flies his Dragonfly through the center of the vessel.

[Cykeisme]

Assuming we had access to magitech materials that were super light and super strong, would a counter-rotating dual rotor system (one rotor on top of the other) to cancel out rotational momentum possibly work?

I'm assuming in 33 years someone must have considered it, but the transmission required for such a setup would end up too complex and heavy to work on a human-powered machine, I'd imagine.

[Sea Skimmer]

In principle the idea shape without going to these span loading designs should actually be twin intermeshing rotors, as that's by far the most stable possible configuration for helo rotors. However it won't really work for a human power machine running at low RPMs because the blades would end up so long they might strike the ground if we could make them at all. Great for logging and SAR helicopters though; low speed has kept it from ever being used for much else.

I doubt a contrarotating transmission would be any more heavy then gearing to four different rotors, this is an issue in real helicopter but that's mainly because of the weight of the complex control system, not the mere power gearing. The issue here seems to instead just be getting enough blade area. Magitech might make that go away, I dunno. You might still have issues with the oscillations introduced by such an unbalanced power such as human locomotion simply requiring multiple rotor hubs to dampen out.