## Help Design a Human-Powered Helicopter

My hopes are dashed (see my post #43) by the following outlandish rule...

http://www.vtol.org/awards/hphregs.html#4.
 4.1.2 The machine shall be a rotary wing configuration capable of vertical takeoff and landing in still air, and at least one member of the crew shall be non-rotating.
Or...I will require a freshly made, newborn volunteer, as light in weight as possible, to function as the fifth crew member, suspended in a non rotating, centrally located bassinette.

After more internet searching than I expected in order to circumvent infant labor laws, I discovered that the "world's smallest midget" is 28 inches tall. With some proportional comparison, this yields a nominal body weight of 18 pounds. Erroring on the conservative side, I expect to obtain the services of a 25 pound dwarf to provide the requisite fifth, non-rotating crew member.

After providing for a crash cage and mechanism to provide non-rotation of the central crew member plus the supporting cables, the central mass should weigh an effective 50 pounds. With four cables tensioned at 200 pounds apiece running to each Condor pilot's center of lift, the fifth pilot should be suspended at an altitude of 1/16th the flight radius below each Condor's lifting surface.

After some back of the envelope considerations, the flight radius of each Condor should be about 400 feet. This implied that the fifth pilot will be suspended 25 feet below the lifting blades.

To meet the requirement:
 4.4.1 The flight requirements shall consist of hovering for one minute while maintaining flight within a 10-meter square. During this time the lowest part of the machine shall exceed momentarily 3 meters above the ground.
the blades will be required to obtain 35 feet of altitude + 3 feet of suspended fifth pilot = 38 feet. This is within some small ground effect for each Condor (wingspan of 100 ft.).

The overall diameter of the Helicopter will be about 900 ft.

 Will each Condor provide the centrifugal force necessary to tension the cables to the 5th crew member? Each Condor will obtain about 25 feet per second, based upon the information from Wikipedia. Using $$v^2 = ar$$ were v =25 feet per second and r = 400 feet The centripital acceleration of each Condor will be 1.6 foot pounds per sec2. The mass of each Condor will be about 32 Kg plus pilot (wikipedia reference, again). After some calculations, each Condor is capable of providing only 10 pounds of radial force to hold up the fifth crew member. This is unacceptable. Ideas anyone?

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 Quote by FredGarvin I'll absolutely dismiss it. The power that can be provided by a good cyclist is somewhere in the area of 300 W. Not only will you be hard pressed to find a very light person that can put out that kind of continuous power, ...
It's not very continuous, but olympic calibre athletes can do work at 600W for 6 minutes. Such an athlete might helo across a hefty lake then, never the channel.

 Quote by mheslep It's not very continuous, but olympic calibre athletes can do work at 600W for 6 minutes. Such an athlete might helo across a hefty lake then, never the channel.
Damn, if they can do 600W for 6 mins thats extremely impressive.

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 Quote by Cyrus Damn, if they can do 600W for 6 mins thats extremely impressive.
To my mind, olympic rowers in these time frames (6 minutes), out perform any other athlete type.
The athletes are frequently tested on ergometers (flywheel machines). The world record a few years ago was 5 min 36 s. over 2000 meters. That's a continuous power output of 590W, i.e. work done on the machine. Over 500M (1m 16s) these guys can exceed 1HP. I've tested at the 2k distance a hundred times in competition and came in, ehem, somewhat lower. The typical top 10 school college rower (male) will rate at about 430W.

BTW, the do-it-yourself helo would have to hold that record holder's 97kg, 2m to get that power:

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 Quote by mheslep It's not very continuous, but olympic calibre athletes can do work at 600W for 6 minutes. Such an athlete might helo across a hefty lake then, never the channel.
Yeah. I wouldn't use that as a data point. Those are definitely outliers from the norm.

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 Quote by FredGarvin Those are definitely outliers from the norm.
So is this idea of a human powered helo.

 Blog Entries: 2 Recognitions: Gold Member Science Advisor The point is that a helicopter like is being proposed needs at least 1hp (745W) to fly (I'm still convinced it would be more, but flying within the ground effect does help). The problem is, every pound kills you, and "successful" designs like the Davinci III only had an available payload of 59kg (130lb) for the pilot. Even powerful professional athletes which are significatly heavier cannot sustain that kind of output for very long.

 Quote by Mech_Engineer The point is that a helicopter like is being proposed needs at least 1hp (745W) to fly (I'm still convinced it would be more, but flying within the ground effect does help).
I just showed you a calculation concerning the power.

 The problem is, every pound kills you, and "successful" designs like the Davinci III only had an available payload of 59kg (130lb) for the pilot. Even powerful professional athletes which are significatly heavier cannot sustain that kind of output for very long.
That's right exactly right, and the power goes with the weight^(3/2).

 Does anyone know how high Allen flew crossing the English channel? My second question would be, what is ground effect as a function of wingspan? Edit: I've been searching for Bryan Allen's estimated power output and weight while crossing the channel and haven't found them.

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Ground effect is essentially any height below one rotor diameter.

 The aircraft was powered using pedals to drive a large two-bladed propeller. Piloted by amateur cyclist Bryan Allen, it completed the 35.8 km (22.2 mi) crossing in 2 hours and 49 minutes, achieving a top speed of 29 km/h (18 mph) and an average altitude of 1.5 metres (5 feet). The empty mass of the structure was only 32 kg (71 lb), although the gross mass for the Channel flight was almost 100 kg (220 lb). To maintain the craft in the air it was designed with very long tapering wings (high aspect ratio), like those of a glider, allowing the flight to be undertaken with a minimum of power. In still air the required power was of the order of 0.4 horsepower (300 W), though even mild turbulence made this figure rise rapidly.

 That's nearly full ground effect. The root of the wing was maybe 10 feet and the tips another 10 feet or so. This compares to a span of 100 feet. I would expect that ground effect is exponential decaying with height. I think I should discover the difference in total ground effect to none. That is "What is the maximum percent gain in lift due to ground effect?"
 Didn't you like my last post Fred? This thread is about a contest with no practical application, isn't it?
 Fred, on a more serious note, the contents of prize state nothing limiting supporting equipment. Ground effect could be sustained throughout the required excursion to 10 feet by ducting the blades with a circular fence. How are you at hovercraft ducted fans?

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