Aerovelo's Human-Powered Helicopter Wins $250,000 Sikorsky Prize

First time accepted submitter oritonic1 writes "Since 1980, several teams have tried (and failed) to build a human-powered helicopter that could win the elusive $250,000 Sikorsky prize. But a Canadian start-up, Aerovelo, has finally taken the crown with Atlas, a human-powered craft that managed to stay at least 10 feet in the air, for 60 seconds, within a 30'x30' area."

Re:Ground effect

[rotorbudd]

With the speed those rotors are turning, I don't think there'd be much in the way of ground effects generated.

Just an old helicopter mechanic tho, not an aeronautical engineer So I might be completely wrong..

Re:Thrust

[ShanghaiBill]

So my question is, would it be feasible to generate this same level of thrust in a smaller area using the same amount of power?

No. The amount of thrust goes up linearly with the velocity of the airflow, but the amount of energy required to move that air goes up as the square of the velocity. So for the fixed amount of energy that a human can produce, you will get more thrust by it pushing down a large mass of air at a low velocity than a smaller amount of air at a high velocity.

Re:Ground effect

[ace37]

With the speed those rotors are turning, I don't think there'd be much in the way of ground effects generated.

Just an old helicopter mechanic tho, not an aeronautical engineer So I might be completely wrong..

Typically about 1.5 rotor diameters are where it stops helping a traditional helicopeter. In this case, at 10 feet up with a 30 foot diameter, the slow rotor speed notwithstanding it will make a significant contribution. The air below the rotors can't freely move downward until the momentum of the wind dissipates; this energy creates lift.

Ben Berry from Gamera was actually a previous coworker before he went to work on their HPV project.

Source: Aero engineer, rules of thumb there are from asking around at Sikorsky years ago. Also, I don't like how they say this at all, but it at least says the ground effect is significant:

Three years ago, as Staruk and his UMD team began building their first iteration of Gamera, they quickly encountered the boundaries of current aerodynamic understanding. To rise off the ground, human-powered helicopters are helped by a phenomenon called ground effect, in which wings close to the surface of the earth experience a sharp reduction in drag. It's very helpful in getting off the ground but difficult to model. "Ground effect is a very complex phenomenon; there are all sorts of vortices," Chopra says. "You can only validate experimentally. There isn't much theory."

http://www.popularmechanics.com/technology/aviation/diy-flying/two-teams-one-dream-the-human-powered-helicopter-15354870-2 [popularmechanics.com]

Re:Ground effect

[ace37]

I forgot to mention the most important part -- the majority of the flight is done very low:

Power required is shown for rotor height of 60 cm (2 ft) above the ground. The 60-second duration flights will be flown as close to the ground as possible to increase ground effect advantages.

http://www.agrc.umd.edu/gamera/gamera2/gamera2-rotor-blades.html [umd.edu]

Re:Intent of the Prize Criteria?

[Rudisaurus]

The AHS publication of the Sikorsky prize regulations, Flight Requirements 4.4.3 [vtol.org], states that "a reference point on the non-rotating part of the machine will be established as a means whereby the observers can judge that the machine stayed within the confines of the 10-meter square", thereby clearly indicating that one point on the machine must remain within a 10 m x 10 m square, not the entire machine.