Human Powered Helicopter Aims To Break Records 87
An anonymous reader writes "A team of 50 from the University of Maryland has developed a human-powered helicopter, 'The Gamera,' which took two years to complete. The size of the helicopter is one third of a football field. The helicopter is made from light materials such as balsa, mylar, carbon fiber and foam and weighs about 210 pounds. The team aims to have it hover at least 3 meters off the ground."
Misleading summary (Score:4, Informative)
The article summary is quite misleading given that the 210-pound figure includes the weight of the pilot.
Re:How much excess power does vertical flight requ (Score:4, Informative)
...compared to just climbing up a ladder?
What I mean is the human body has easily enough power to raise itself up a vertical ladder or rock face so presumably a huge amount of this power must be lost just moving air around when that power is used inside a human powered helicopter. But how much power is wasted , or to put it another way , how much power put into the system is actually used to raise the mass of the helicopter?
You're mixing mass, power, and impulse all together. impulse = F * delta t = m * delta v
So the force is pushing down with the combined weight of the vehicle for a certain time in order to hover in place, which is equivalent to accelerating a mass (lets say, the vehicle) to a certain velocity. So hovering for 10 minutes takes the same impulse as accelerating (lets say, horizontally) to some absolutely ridiculous velocity. I forget the crossover but, hovering a copter for X minutes is equivalent to pushing a car 0 to 60.
The power level is in the low single digit horsepower for a good athlete for a minute or two. Good luck dissipating even one horsepower for a "long time".
Also note that people climb extremely slowly. Over a long term, best expressed as seconds per foot rather than ft/sec. Classic high school physics problem is having the strongest track athlete try to climb a flight of stairs as quickly as possible, with the horsepower result usually being pretty depressing.
Re:Stored energy (Score:5, Informative)
Easy, fly higher.
Ground effect only happens when you're close to the ground. A rule of thumb is that it's effect is negligble after you reach a height equal to half the wingspan.
So a rotor blade (or wing) of 3m length (6m rotor disc/wingspan), once above 3m in height, would have to be flying out of ground effect.
And yes, ground effect is a big deal - it lowers the amount of lift you actually need by quite a bit. Student pilots find this out on landing when all of a sudden the airplane floats down the runway. Experienced pilots find it when their plane seems to take off, but only bobs above the ground without really gaining altitude.