Human-powered Helicopter Fails to Lift Off

Peter writes "The Human-powered helicopter didn't even get off the ground. A team of University of British Columbia engineering students tried to win the $20,000 US prize offered by the American Helicopter Society. Three metres off the ground and hover for a minute was the challenge. But before the rotors were able to produce enough buoyant force they hit each other. More details: Vancouver Sun."

Comments

Re:Point?

[fireman sam]

The point is that this type of research could lead to more efficient lift mechanisms for conventional aircraft. Allowing longer flights with less fuel requirements.

BTW, the Australian Parlament(sp?) past the free trade agreement, so we now have software patents, yay!

Design vs Implementation

[sczimme]

IANAAerospace Engineer.

From reading their Project Status/Schedule page, it appears their problems may have arisen during the manufacturing stage:

July, 2004

It has been a while since our last update. We have been busy.

COMPOSITE SPAR MANUFACTURE/TESTING

All spars have been cooked including the tapered sections. Assembly of all this is complete for the four wings. Static testing was carried out for the assembled spars. All four eventually passed the test (see Thunderbird Projects - Picture gallery).

WING CONSTRUCTION

All four wings (for the two rotors) have been completed. This includes all wing parts (leading edges, trailing edges, suction side, ...) and assembly (see Thunderbird Projects - Picture gallery).

"Eventually passed the test"? Uh oh.

[There were no updates from December 2001 to July 2004]

December, 2001

COMPOSITE SPAR MANUFACTURE/TESTING

Static testing has been carried out for the CFRP spars. Static tests included both bending and torsion. A large effort was put in manufacturing the tapered mandrel for tapered composite spar production. One tapered spar has been manufactured with disastrous results. The tapered mandrel still requires some work (modifications). Composite spar manufacture continues (including straight sections).

It appears there were construction issues early in the project.

I am certainly not knocking their efforts. However, even the most elegant design can be compromised by sub-optimal manufacturing/implementation resources. I wish them the best in the next iteration.

That should read average human body...

[TamMan2000]

The human body constantly generates an approximate 200 watts

You mean the average human...

Lance Armstrong can sustain power outputs around 600 watts, and several people (most competative amatuer cyclists) are capable of a ~1 minute burst of over 1250 watts.

Re:That should read average human body...

[Overzeetop]

Yes, that's true. In fact, most healty indivduals can generate more than a horsepower (746W) for very short bursts. To prove this to yourself, find a flight of stairs and time yourself running up them:

Your weight in lbs x floor to floor height in feet / seconds to climb / 550 = horsepower

Don't live in the US?
Your mass in kg x 9.82 x floor ht in meters/ seconds to climb = watts

blades not stiff enough?

[mks180]

"the atmospheric conditions caused a dangerous imbalance in the craft's two rotor blades: the bottom blade was producing lift while the top blade wasn't." Sounds to me that what really happened was that they tried to save weight and didn't make the upper blades, which are longer, torsionally stiff enough. This caused a phenomenon similar to aileron reversal: as you produce lift, you produce a nose-down pitching moment which can elastically twist the blades, and may be capable of reversing the direction of lift. If this is what happened, then I can easily see the upper blades flapping down into the lower set of blades.

This aileron reversal effect is actually a fairly hot research topic in the rotorcraft community. People are trying to exploite it by using embeded actuators to control trailing edge flaps to create a pitching moment to twist rotor blades and thereby eliminate the swashplate for primary control.