# The concept of flapping flight will eventually succeed!

### Help Support Homebuilt Aircraft & Kit Plane Forum:

#### DennisK

##### Active Member
I don’t understand why proponents of flapping wing flight can base their opinion on this notion that nature knows what it’s doing while simultaneously ignoring that in broad terms the larger the winged flying creature, the less it flaps to stay aloft. A fruit fly flaps like crazy, an albatross hardly ever flaps, and a quetzelcoatlus may not have flapped at all. I don’t know the reason for that trend; perhaps it’s energy management, or structural limitations, or something to do with Reynolds Numbers, or likely a bit of each.
I think power to weight ratio is the main issue, though I'm not sure exactly what biological factors limit it. There are two allometric bird scaling equations derived from measurements of real birds: wingspan = mass^0.4 and power = 60*mass^0.667. The higher wing loading makes sense because speed tends to increase with size. The lower power to weight ratio is probably why large birds are less inclined to flap. So we just need more power, which is entirely plausible to achieve. For example the equation predicts 1.3kW for 100kg, which does seem likely to struggle. But if we instead plug in a large bird weight like 10kg, the predicted power is 279W, and scaling linearly to 100kg gives 2.79kW. That seems more likely to work, and still much lower than a propeller. Even if you start with 5kg like a big Canada goose, you get 175W*20=3.5kW, which is still good.

Please clarify the instructions. Do you remove the feathers? If so then when and how? Can they be recycled into a flying machine with flapping wings? Are plans available?
Yep, a couple holes drilled through the shaft and they could be used the same as my fiberglass/carbon feathers. It's on my list of things to try if I have aerodynamic trouble once everything else is working. Though I probably wouldn't ever fly it since they wouldn't be replaceable if broken.

#### Dan Thomas

##### Well-Known Member
I don’t understand why proponents of flapping wing flight can base their opinion on this notion that nature knows what it’s doing while simultaneously ignoring that in broad terms the larger the winged flying creature, the less it flaps to stay aloft. A fruit fly flaps like crazy, an albatross hardly ever flaps, and a quetzelcoatlus may not have flapped at all. I don’t know the reason for that trend; perhaps it’s energy management, or structural limitations, or something to do with Reynolds Numbers, or likely a bit of each.
Animals and people walk, but I don't see vehicles walking, unless we count the robotic dogs or the huge excavators for which tracks aren't strong enough. A walking car would be highly impractical, with all the mechanism needed to work four legs and maintain balance, instead of four simple wheels. Rough ride, too. The developers of early vehicles modified carriages with internal combustion engines or steam engines. They didn't make mechanical horses.

1950...

#### Dan Thomas

##### Well-Known Member
So show a video of it actually travelling by walking or trotting or running. Don't think you'll find any. A fine invention for the time, but if it can't stay upright it's useless. Not rideable at all.

This is what it takes: a $40-million computerized machine that makes a real horse look graceful and powerful by comparison: #### J.L. Frusha ##### Well-Known Member So show a video of it actually travelling by walking or trotting or running. Don't think you'll find any. A fine invention for the time, but if it can't stay upright it's useless. Not rideable at all. This is what it takes: a$40-million computerized machine that makes a real horse look graceful and powerful by comparison:

Most weren't designed to ride, but to pull carts and wagons.

If you design an airplane, don't expect it to swim, unless it's designed to be a submarine, too.

Hell, you're splitting hairs and all you have is high-dollar fails to show?

Last edited:

#### Dan Thomas

##### Well-Known Member
I've seen that. It's a horse with wheels that roll. A statue on casters. That's not walking. That's not splitting hairs, either. It's a fact.

The only artificial horses that actually walk are those $40 million things, and they aren't going to replace automobiles, which was my point in the first place. Mimicking nature isn't always the best way. As a pilot for 47 years, I can't see that flapping wings are going to achieve anything practical. Many attempts so far, and nothing has come of it. They certainly won't get you an affordable flying machine that can go places. There's an awful lot of talk, and little action on so many ideas here. I know of guys that have talked for decades about their ideas and what they're going to build, and now they're old (or dead) and they never flew anything. Most never even built anything. Life is short. It shouldn't be wasted on previously-tried ideas that didn't work then, and that require so much more time and money than a simple homebuilt to make them work now. #### OrVNstabilize ##### Active Member The only artificial horses that actually walk are those$40 million things, and they aren't going to replace automobiles, which was my point in the first place. Mimicking nature isn't always the best way. As a pilot for 47 years, I can't see that flapping wings are going to achieve anything practical. Many attempts so far, and nothing has come of it. They certainly won't get you an affordable flying machine that can go places.
While I agree with your assessment of robotic horses as an example of mimicking nature not always being the best way or working out, I wouldn't go as far as to paint flapping wings with the same brush. Although at face value it seems to make total sense logically leading some to suggest that if birds could have evolved propellers then they'd be much better off. But we are talking about a ground based mode of transport and another that is air based here they operate on totally different set of rules, variables, and physics(with certain aspects that seem to be total opposites of one another). You only need to look at the many failed attempts at making a car that could also fly to understand the differences. Flapping wings doesn't need to replace anything, it just has to be able to fly. Nobody even has a clue how flapping wings actually work or to properly build one so I wouldn't even call them attempts.

Sure you could say this is all just wasted effort if you look at it selfishly but where would we be today if it weren't for those few individuals who never built or flew anything and sacrificed themselves to pave the way forward? It is on their shoulders that you were able to enjoy flying for 47 years and similarly for a few many others here as well I assume. However flying is still out of reach for the vast majority of people so if one could help in some regard by making it more accessible to more people then it wouldn't be wasted?

Last edited: