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Old Mar 26, 2014, 08:34 PM
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Joined Dec 2013
43 Posts
Foldable Wings

This thread explores wing fold.

Fold is defined as a retraction of the wing laterally along the horizontal plane and occurs perpendicular to the flap axis.

Fold is present in all vertebrate natural models. http://arthropter.blogspot.com/

Why aren't we doing this?

Examples of man-made wings that fold?

What are the benefits of fold?

What are the costs of fold?

When is the wing folded?

-wing retracted for upstroke
-wing extended for downstroke
-gliding (no flap) extended and retracted for control

Examples of biological wings that fold:

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Last edited by pteronaut; Mar 26, 2014 at 08:44 PM.
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Old Oct 21, 2014, 07:32 AM
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Joined Oct 2014
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im as well thinking about the folding possibilities

making the wingarea as small as possible one upstroke to save energy is one point

another point is the form of the vortex if you look at this paper http://www.google.de/url?sa=t&rct=j&...,d.bGQ&cad=rja

you will see that there is a relation between the flapping and the vortex shape


Examples of man-made wings that fold? there are some examples ...

http://eutytoalba.deviantart.com/art...IDEO-377858529 (maybe just fun, but interesting)

SMA morphing wing 01 (0 min 23 sec)

this one is maybe interesting, because some bats (esp. fast flight) and many birds do this kind of folding motion during fast flight.

there are some more examples like telescopic contractible wing


i as well observed that birds and bats (
Bats in Slow Motion 1 (0 min 37 sec)
) strech during downstroke and pull the wing up but letting the wing tip showing down and at the the transition between upstroke and downstroke they fold or spin/twist the wing due to less drag i suppose during this movement they dont want to get slow down...

in my oppinion an interesting technical realization would be to roll the wing partially up and out before downstroke or to pivot the whole wing back and forward

problem is the technical solution for this problem, it is not as simple as the existing ornithopter flapping mechanism and 4bar linkage gears (sorry for step on someones toes ...)
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Old Oct 21, 2014, 12:29 PM
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Joined Aug 2014
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Pterosaur wing folding doesn't comply with what is called out in arthropter blogspot. Also, they can't hyperextend their ankles into the position shown.. Ankles will only extend to about 165 degrees.
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Last edited by JimC3; Oct 21, 2014 at 06:08 PM.
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