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Old 04-14-2005, 01:09 PM   #1
Like a bird
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Human powered wing design.

Hi everyone, I have been building a human powered device for a couple of weeks now and I have everything done . But I am still looking fr the best and most efficient wing design for a human powered ornithopter. I have built a couple of wing prototypes of my own design and they both worked to a point. Both broke under the force of arm power, and my finished design is leg powered, which are 4-5 times stronger than my arms. So you see my problem, right now I am in the testing phase so my wings are only half of what they will be in the finish device. If anyone has any wing designs they would like to pass around for opinons please feel free to do so,. The goal here is to find and efficient design to go with. I will post pics of what I have done so far.

Thankyou.

Last edited by Like a bird; 07-06-2005 at 12:19 PM.
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Old 04-14-2005, 04:09 PM   #2
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Light weight.

Ok I have just caculated my manned ornithopter's weight and it is better than I expected. Both wings come in at a weight of 20 lbs and the V-tail set up comes in at 5 lbs. The drive mechanics and frame come in around 10 lbs with 5 lbs mics. So a total of 40 lbs, I can lift that with one hand. I have yet to see a human powered ornithopter as light as that even though we have the material technology to do it. The materials that I used were seamless drawn aluminum tubing and wood for the wings, tail and frame. Now will it fly ? Good question, so far I am still testing a small version of it but I have achieved forward motion on arm powered trust alone.

Last edited by Like a bird; 04-14-2005 at 04:11 PM. Reason: grama
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Old 04-14-2005, 04:58 PM   #3
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Sorry I don't have any ideas to help with the wings at this time, however, I am eager to see pictures of this thing. Good luck.

jason
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Old 04-15-2005, 12:05 AM   #4
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Thanks alot "wingnut" as you can see my wing building is not all that. But my drive mechanics are the real jem, I think that I have to patent that before I place pics of it on the forum. But I will place drawings of my design goals or prototypes.
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Old 04-28-2005, 12:30 AM   #5
Kinkade
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Hey, the reply button actually works in THIS forum..how refreshing!

I'm just wondering....are you expecting to actually build something that flies?

In my opinion a human powered ornithopter is possible, but most likely only if powered by an olympic gymnast like Kurt Thomas in his hey day or someone like that. Someone whose upper body strength to weight ratio is incredible and enough to hold a long iron cross on the rings.
The pilot would need incredible upper body strength unless the machine utilized leg power. Better yet, a parapleigic olympic gymnast would be even better because who needs to haul around leg weight.

Even with such a pilot you would need a state of the art wing design and carbon fiber construction, and a really big hill with a good headwind.

Sean
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Old 07-05-2005, 01:45 PM   #6
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You are right Sean, so right. I tested my invention using leg power, even though I was proffessional athlete in three sports as of 2001. I could only manage 4 - 5 beats per second thats with better designed wings. I could only keep that up for a few minutes, so it was back to the drawing board.
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Old 07-05-2005, 05:09 PM   #7
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Just a little question for you, assuming that you will try to fly this machine, how big is that wing going to be when it's... fully grown? Be aware that to lift the weight of your own body plus the weight of a machine, you will need a minimum of about 25 square metres (or about 230 square feet) of total wing surface flapping at a high frequency...!

I've been researching manned (and man-powered, for that matter) ornithopters for a short while now, and I've found that it would be pretty hard to build a man powered ornithopter that is both stong and light enoung to really fly.

Don't get me wrong, I'm not trying to bring you down, I'm just interested.

I must say that I am looking forward to seeing pics of your design...

Good luck on building (and possibly on flying!).
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Old 07-06-2005, 09:58 AM   #8
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Hey aren't we getting hung up on flapping rates when it is power output and endurance that counts? The optimum rate will vary from fast for takeoff at max. power, to slow in cruise for max energy output over the whole flight. Just like a battery, you get max power transfer when the load impedance equals internal resistance (in this case intra-muscular friction) , but that wastes half of your energy. A slow push is much more efficient.

A thesis by Harrison at the University of NSW in about 1970 found that a rowing action using practically all the muscles in the body gave about 10% better power and energy yield than pedalling with legs alone. Cyclists claim that they too use every muscle but unless they swing from side to side out of the seat, as for a sprint, the arm and torso muscles are used for bracing only and generate little power.

So I reckon that an ornithopter should be powered by a combined arm, leg and torso action like rowing but not necessarily in a seated position. I favour a face-down arm and leg pushing action for the downstroke, like a weightlifting clean-and-jerk. As in rowing, the fastest rate will be about 1/second. Clearly it is most efficient to couple this motion directly to the wing stroke rather than through a rotating mechanism to make the wings flap at a different rate than the rowing.

We know from propellor powered HPA's that we need about 300W for level flight. Thus we need to deliver about 300 joules per stroke, or 30 kg wt. force over one metre. If we work in push-pull we can bring that down to 15 kg force or probably split it 20kg force on the downstroke and 10kg force on the upstroke. That sets the design parameters for flapping amplitude, leverage and Cl range of the wing and the stiffness of the preload spring. The hand and feet levers must also be desigend to apply control inputs.

It will be real hard work to sustain that effort over a decent flight, so we better make sure that we have minimum weight, large span, slow cruise speed, high L/D airfoil and smooth body fairing to minimise drag. Every aspect of the design affects every other and all must be optimised through repeated iterations. Meanwhile exercise like hell.

Last edited by mscott; 07-06-2005 at 10:12 AM. Reason: clarification
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Old 07-06-2005, 11:10 AM   #9
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Well as far as the wing design I suck at it, but getting much better it in a hurry. Like they say knowledge is key and I am learn at a frantic pace. As far as the mechanics go, that's my thing. I've designed and built a prototype that allows me to shrink that needed much needed square footage to a minimum. Think Otto Lilienthal he had many successful glides of over 800 feet with a heavy 190 sq/ft of wing surface. Now that was back in 1896 and even he didn't need 230 sq/ft of wing surface. Now fast forward to too days world where people hang glide for miles at a time using only 144 sq/ft of surface. And that is without any powered assist, if you add in a motor to that equation your wing area pretty much shrinks where I am at. Yes I haave given up on the human powered version of my project, in exchange for a motor so as to decrease my wing span. I have sucessfully invented and built a drive system that will allow me to reduce my wing area to very little indeed. And as far as flapp frequency, wow. But some one other than myself will have to build the wings for me but I do have a design for those as well.
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Old 07-06-2005, 11:33 AM   #10
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You are on the right track MSCOTT, but the thing that turned me back to motor powered flight is the fact that with human powered flight the wing span has to be large and the performance too low. My reason for wanting to fly is to do so more like a bird than like a giant man thing. So when the idea on how to make a motor power flapping device came to me late one night, I built it. And it works perfectly, I just need wings.
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