The concept of flapping flight will eventually succeed!

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jedi

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A little guidance might be helpful.

The following statements are assumed facts to be accepted by all responders.

Flapping UAV (Unmanned Aerial Vehicles - AKA models) have already flown successfully.

A few man carrying ornithopters have flown. They have had limited performance and were not a commercial success.

The aerodynamics and mechanics of flapping flight are areas that need to be understood and demonstrated if manned flapping flight performance is to be improved.
 

Sraight'nlevel

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I think nature does give us very good information, but human innovation cannot be dismissed.
 

jedi

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I think nature does give us very good information, but human innovation cannot be dismissed.
I would like to add "I think nature does give us very good information" and examples.

We can not discuss flapping flight in detail without investigation into various modes of operation.

Humming birds have a hover mode and a high speed mode of operation. What are the differing principles of flight, if any, that operate in each mode?

Humming birds are very small and light and difficult to observe in detail. These same modes are observed in some larger birds to a lesser degree. How does the scale factor enter into their operation?

Sparrows and some other small birds have a fly/fall flight path. What are the dynamics behind that?

Larger birds (pelicans and storks for example) have a flap and glide flight path. What flight dynamics are behind that characteristic? Is there more to it than just soaring and gliding?

My favorite. What is going on aerodynamically when ducks make that steep powered descent into a small pond surrounded by tall trees?

Plus many more to add to the list.
 

OrVNstabilize

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The aerodynamics and mechanics of flapping flight are areas that need to be understood and demonstrated if manned flapping flight performance is to be improved.
This. it wont matter what state of the art or futuristic motor/engine/actuator, power source, materials etc. you invent but without the knowledge and understanding of the mechanisms responsible for lift and thrust generation then flapping flight will not succeed.
 
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henryk

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My favorite. What is going on aerodynamically when ducks make that steep powered descent into a small pond surrounded by tall trees?
=I was made this with the classic hang glider=

stepped descent=sharp AoA increasing/>
short normal glide...many times and soft landing.
 

Dan Thomas

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My favorite. What is going on aerodynamically when ducks make that steep powered descent into a small pond surrounded by tall trees?
High angle of attack, draggy, and lots of dihedral to reduce effective wing area and span. Airplanes use the first two techniques and a bit of the third for steep approaches. Flaps increase angle of incidence and therefore AoA and therefore drag.

When I was instructing, we used the Citabrias and a Champ before those for taildragger training. The 7ECA and the old 7EC had no flaps, so you either slipped (which reduces effective wing span and present the fuselage side to increase drag) or you just slowed the airplane down. Sometimes if we were high on approach I would get the student to pull the nose up some until the speed fell somewhat, increasing the AOA, and the glidepath steepened enormously. One could end up short of the runway doing that, and we could control the glidepath by lifting or dropping the nose to vary the airspeed alone. Sadly, such stuff is absent from most training syllabi, and so we get pilots trying to fix a high approach by diving at the runway, making everything much worse. You get more speed, often flattening the glidepath as the speed increases to or above best L/D speed, and at the surface all that speed has to be dissipated in low-drag ground effect, and accidents happen all the time due to this. Porpoising and busted nosegears. Wheelbarrowing off the runway. Running off the end of the runway. Blown tires from braking when the wing still has way too much speed and lift.

The birds had it all figured out long ago, but humans have to keep figuring it out over and over again. The hard way. Dumb. The solid relationship between AoA and airspeed has gone right over the heads of most pilots.
 

jedi

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Paul McCready built a half size Pterodactyl under contract. He probably has data archived somewhere.
Did the Paul McCready Pterodactyl flap for propulsion? Did it have a BSLD and adequate yaw control with no vertical stabilizer? I know it had some control issues but do not recall all the issues and how they were solved, if in fact they were solved.

Are there any technical papers on this project?
 

BBerson

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I think it was towed to altitude and may not have been capable or designed for climb. It was made for a movie.
It had two .40 Astroflight electric motors. I did some quick searching but no technical paper found.
 

REVAN

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A lot of people are interested in electric/battery powered aircraft, but the range is always an issue. IMO: the solution to the electric powered aircraft range issue is to use flapping wings. Electric motors work well in power-bursts of short duration. An electric motor that can produce 10 Hp. continuously, can generally produce 20 Hp in short bursts on a 50% duty cycle with the same thermal loading. The only real difference is going to be in the ESC needing the ability to deliver higher current.

I think an effective flapping wing design can likely fly on about half the power compared to a more conventional propeller driven design. So the batteries powering an electric ornithopter will only weigh half as much and the motors will weigh about 1/4 as much as compared to an electric propeller driven aircraft. That all adds up to the real possibility of an effective electric aircraft.

I've heard many people claim over and over that electric man carrying aircraft will not be viable until the energy density of lithium batteries doubles from what can be done with today's technology. Alternatively, half the aircraft's energy requirements with flapping wings and you are already there.
 

bifft

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My favorite. What is going on aerodynamically when ducks make that steep powered descent into a small pond surrounded by tall trees?
If you look at a landing duck the wings are cupped for a high camber airfoil, the webbed feet are spread out as airbrakes, tail also spread for max area. And they are at a high angle of attack as noted above. Usually flap a bit to break the descent just prior to touch down.


Bird style flapping efficiency may require bird style highly variable wing geometry.
 

jedi

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If you look at a landing duck the wings are cupped for a high camber airfoil, the webbed feet are spread out as airbrakes, tail also spread for max area. And they are at a high angle of attack as noted above. Usually flap a bit to break the descent just prior to touch down.


Bird style flapping efficiency may require bird style highly variable wing geometry.
Notice the feathers picking up on the top of the wing indicating a reverse flow over the top of the wing. This is where Whitold Kasper claimed that a lift coefficient of 25 was possible. This is not the same dynamics as an aircraft slow, steep, slipping approach with full flaps or a hang glider in parachute vertical descent.

Henryk touts the high lift coefficient for a vertical descent of the Cascade Ultralight but that is without active flapping. Add the proper flapping to the equations and the force coefficient probably doubles or triples.

It is difficult to explain the aerodynamics but is this really more complicated than adding a turbine engine and blown flaps to get a 120 knot carrier approach speed for an arrested landing. Don't forget, it includes the folding mechanism as a light weight bonus.

Great photo! How bout a caption? Did I flair to high? or - I got this made! My favorite - What you looking at? You think I can't pull this accuracy landing off. Two more flaps and I'm in.
 

henryk

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half the aircraft's energy requirements with flapping wings and you are already there.
=more,then one order !
(1900 N/HP thrust force...)

=simple drive-pneumatic.


=8:17= Vinzenz Chalupsky big ornithopter !

 
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Insects use hydraulics to move their wings, and bird muscle cells move in a linear motion, so bundles of wee hydraulic cylinders could mimic muscles. Coming up with a lightweight hydraulic system could be a challenge, but with Graphene, it’s technically feasible.
 

Brünner

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Insects use hydraulics to move their wings, and bird muscle cells move in a linear motion, so bundles of wee hydraulic cylinders could mimic muscles. Coming up with a lightweight hydraulic system could be a challenge, but with Graphene, it’s technically feasible.
But weight is a non-issue for them. At birds size, it is a big issue.
 
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