Building a semi human powered flying device

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I think Jarno is going to seriously need to reconsider the weight of his device. Using the number of 28 m^2 for the wing surface area...if you covered both sides of the wing with 6 mil plastic sheeting as the skin, the sheeting alone would weigh approximately 7.8 kg or 17.2 pounds...fully half of your design weight of 15 kg.
 
MacGyver1968 said:
Naww....I'm a lot better looking, and Phlog is a lot smarter. :)

Jarno came to this board asking for opinions of his "design"....Phlog and I are doing just that. We are trying to point out that he is majorly underestimating many factors of this design, including weight, complexity of design, power requirements, availability of technology, and the physical limitations of the human body.
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Maybe he has and maybe I can't spell, but I'll tell you a story if only to get my post count up.

I worked for many years in R&D. My boss would often come to me with question, how can we do this that or the other. I learned early on that what he wanted from me were ideas as to how and what the relative cost would be. What he did not want from me was, it can't be done. He would decide if he thought the cost was justified.

Jarno and I have looked at the possibilities and concluded that the goal is reasonable. We have not presented all the evidence here as yet. He and I may not agree on all of the details, we only met a couple of days ago and we haven't shared all of our ideas.

From the response so far, it seems Y'all are content to sit back and tell us, it can't be done with no further thought. You quibble about rough numbers and call us puppets and say we 'look stupid'. Frankly I wonder if either of you have any credentials to base your arguments from authority on.

Do either of you fly? Anything? Do you know anything about the large flying creatures of the past, the pterosaurs and teratorns? Are you current on the latest prosthetic devices and electromyograpic control systems? Are you experts in carbon fiber composite construction techniques?
 
MacGyver1968 said:
Back on topic...

I think Jarno is going to seriously need to reconsider the weight of his device. Using the number of 28 m^2 for the wing surface area...if you covered both sides of the wing with 6 mil plastic sheeting as the skin, the sheeting alone would weigh approximately 7.8 kg or 17.2 pounds...fully half of your design weight of 15 kg.
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You are assuming a lot about materials and construction when nothing has been set in stone.
 
phlogistician said:
Cool, show us the video you undoubtedly took of yourself running with a 28m^2 wing weighing 20kg strapped to your back then please.
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Now why would I need to do that? The Internet is full of videos of hang gliding, go and find them. I can refer you to friends who do it for a living if you like and you can try it yourself. Check out Clark's site at hangglidetennessee.com

Note, I didn't say anything about running on flat ground with no wind. That would be silly.
 
Daedelus said:
Maybe he has and maybe I can't spell, but I'll tell you a story if only to get my post count up.

I worked for many years in R&D. My boss would often come to me with question, how can we do this that or the other. I learned early on that what he wanted from me were ideas as to how and what the relative cost would be. What he did not want from me was, it can't be done. He would decide if he thought the cost was justified.

Jarno and I have looked at the possibilities and concluded that the goal is reasonable. We have not presented all the evidence here as yet. He and I may not agree on all of the details, we only met a couple of days ago and we haven't shared all of our ideas.

From the response so far, it seems Y'all are content to sit back and tell us, it can't be done with no further thought. You quibble about rough numbers and call us puppets and say we 'look stupid'. Frankly I wonder if either of you have any credentials to base your arguments from authority on.

Do either of you fly? Anything? Do you know anything about the large flying creatures of the past, the pterosaurs and teratorns? Are you current on the latest prosthetic devices and electromyograpic control systems? Are you experts in carbon fiber composite construction techniques?
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No one here said it can't be done...nor has anyone called you stupid. You are putting words in our mouths. Jarno asked for our opinions and we gave them. If you don't like them..then go elsewhere.

I too have worked in R&D...and I'm not going to blow sunshine up someone's ass if I see major problems in the feasibility of their design. I'm going to point them out...so the design can be improved...or scraped if the hurtles are too great to overcome.
 
Daedelus said:
You are assuming a lot about materials and construction when nothing has been set in stone.
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I can only comment on what limited data we have been given. Jarno said he wanted to keep the weight to around 15kg....and estimated the wing surface to be 28m2....that's all we have to go on. I was just trying to point out that plastic sheeting...something that is lightweight and readily available... to be used as a skin for the wing would eat up half of his weight requirement...and that maybe he need to reconsider his weight requirements.

Edit: You said you were into hang gliding? Just curious..what material is used for the "skin" of the hang glider...and how much does it weigh just by itself? Although I used the example of plastic sheeting for the wing's skin...I don't think it would hold up to the forces involved in flapping...maybe hang glider material could be used.
 
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Stupid and dishonest were words used. Also accusations of sock puppetry alright? If we can get past the name calling well and good.

Yes, you have limited data and yes some of the critiques are warranted. 15kg does seem unrealistic even to me. My first hang glider in 1973 weighed that much and it had a 3:1 glide but it did soar in ridge lift and once flew from that same site in the Dreaming Awake video. Most modern solo gliders weigh around 70 pounds (sorry for the English conversion), with another twenty or so in equipment.

The sail of a hang glider has been Dacron for it's non stretch quality, but there are lots of composites of Mylar for additional stability and finish.

I'm not aware of what Jarno plans to use in his design for a wing covering. Personally I like the idea of fabricating feathers out of carbon fiber composite. Primaries would be some 8 feet long. And no, I haven't calculated the weight of an individual feather.

I am making a leap in thinking that if nature can build a feather, we can build one even lighter and stronger. If nature can build a frame of hollow bones, we can build Carbon fiber bones on foam cores that are lighter and stronger. If nature can build a power actuator, a muscle, well we already have them both lighter and stronger. If nature can build a nervous system that can control all that, we can use our computers and our own brains to fly our creation.

It's a leap, but a reasonable one, just like the one I take and have taken thousands of times off the ramp at Henson's Gap, TN.
 
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Mod note: I’m enjoying this robust discussion; hopefully others are as well. In order to aid that potential enjoyment I’ve removed some off-topic posts, such as arguments over sockpuppetry. Any accusations of such can be reported to me via the Report Post button or via PM. Try to keep it civil everyone. ;) Thanks.
 
Daedelus said:
Stupid and dishonest were words used.
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Yes they were, when a selective quote was made, excluding the dimensions of what I said could not be made, and later, when you were referring to a smaller surface area, not the one I was critiquing.

If you want to focus on the smaller wing area, fine, but just be clear about it.
 
I believe what you guys are talking about is actually called an Ornithopter. Last year the University of Toronto created one that used a bicycle like construction to "flap" the wings. It had a 32m (105') wingspan and weighed 93lbs. It was constructed of carbon fiber, balsa and foam. It needed to be towed by a car to get off the ground and then only remained in flight for 20 secs. As the wings did not articulate (as a birds) they relied on the flexing of the span and their shape to provide some lift.
I don't believe we currently have a power supply light enough or motors for that matter to do what you're talking about here. Unless of course you can find someone the size of an infant with the strength/endurance of an Olympian.
 
phlogistician said:
So you intend to hang from a flapping structure? Sorry, I had thought this rig was attached to the pilot, but now you are saying he just hangs from it?
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I don't know where you get that. Yes pilots hang from a hang glider (hence the name, right?). But a hang glider is simply a data point that demonstrates what can be done with some Dacron and Aluminum tubing.

The machine being suggested is quite different in form and function.
 
phlogistician said:
Yes they were, when a selective quote was made, excluding the dimensions of what I said could not be made, and later, when you were referring to a smaller surface area, not the one I was critiquing.

If you want to focus on the smaller wing area, fine, but just be clear about it.
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And if you can make your points without the ad hominems, it will be greatly appreciated. You were critiquing a size wing that was a starting point in a string of calculations leading to the smaller more reasonable size.
 
Ellis said:
I believe what you guys are talking about is actually called an Ornithopter.
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Some of us are talking about ornithopters. Unfortunately that name has been applied to any number of machines that have wings that go up and down. IMHO, taking a perfectly good airplane and flapping the wings is silly and inefficient.

What has been proposed at the start point of this discussion is a return to first principles, bird like flight. No one can point to the Snowbird and call it more than vaguely bird like. What we are talking about is using the structure of an actual bird as the prototype and model for a machine. And yes we realize it's been done before, but until now, no one has had the technology and materials to succeed. We believe the time is now for such an endeavor.
 
Daedelus said:
The machine being suggested is quite different in form and function.
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Which is what I was actually getting at, I was being facetious.

If your machine is different to a hang glider, making analogies to hang gliding is not relevant.
 
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Daedelus said:
And if you can make your points without the ad hominems, it will be greatly appreciated. You were critiquing a size wing that was a starting point in a string of calculations leading to the smaller more reasonable size.
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The ridiculous wing size gave a reasonable running speed. The calculations then went the other way, with a rather unlikely running speed.
 
Ellis said:
I believe what you guys are talking about is actually called an Ornithopter. Last year the University of Toronto created one that used a bicycle like construction to "flap" the wings. It had a 32m (105') wingspan and weighed 93lbs. It was constructed of carbon fiber, balsa and foam. It needed to be towed by a car to get off the ground and then only remained in flight for 20 secs. As the wings did not articulate (as a birds) they relied on the flexing of the span and their shape to provide some lift.
I don't believe we currently have a power supply light enough or motors for that matter to do what you're talking about here. Unless of course you can find someone the size of an infant with the strength/endurance of an Olympian.
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It was very elegant in it's first flight:

http://www.youtube.com/watch?v=0E77j1imdhQ

The only problem...it was only able to achieve 16 wing flaps before the pilot was completely exhausted....and that was using his legs.

Jarno's design utilizes arm strength instead...which has even less power. It why I suggested ditching the human powered aspect of the design all together and go pure mechanical.
 
Daedelus said:
No one can point to the Snowbird and call it more than vaguely bird like.
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Well, no, given that birds don't weigh nearly a hundred pounds, or need towing by a car to get them airborne.

But that is what current technology can achieve. You want to remove the tow start, the bicycle wheel, and lessen the weight by more than half?
 
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