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The Swallowtail Challenge. Answered

Apparently, swallowtail butterflies have posed a bit of a puzzle to the sort of chap that studies that sort of thing.

Butterflies actually have two pairs of wings - fore and aft, if you like.  Most butterflies have these pairs separated, to allow greater control over their flight, but swallowtail wings overlap, effectively becoming a single wing.

They are stuck with a simple up-and-down flap.  The puzzle was; where does the control come from.

It is hard to measure the forces acting on and in a live butterfly, so the researchers built a model - a small version of the hobbyists rubber-powered ornithopter, the same size and weight of a real swallowtail.

They cast replica wings from fluorocarbons and polyurethane, and set it off in front of slow-motion video cameras.

The conclusion?

The unique shape of the wing provides automatic control - the combination of flexibility of the wing and the rigidity of the veins provide a passive control and stability.

The point?

Why am I posting this here?  As a challenge: the swallowtail ornithopter was (except for the wings), very basic - wire frame and a rubber band.

How small could such an aircraft go?

How tiny could you, dear reader, build a working ornithopter?


Institute of Physics article.
(Free registration required to read it in full, if you are quick)


Discussions

Here is what I made

IM003058.JPGIM003059.JPG

Oh, my goodness! Does it actually fly?

It has a jerky motion but it can fly for about 3 to 5 feet if I wind it up to the maximum limit. That coin is a quarter for the comparison.

And can you feature the comment?

Looks like the same layout as royalestel's design, which is the same layout as the Make Weekend Project. The stick out the front of the butterfly appears to just be holding the wings still for a photo.

Translation: the instructions are already there, just make them little and make cool cutout butterfly wings.

Having watched the video a few times I believe the stick out front is there to adjust the center of gravity.

There are two separate challenges:
  • Engineering the mechanism to be small, yet able to overcome friction (the swallowtail model had a very jerky motion).
  • The wings themselves - the team above cast their wings in photo-etched moulds

The jerkyness seems part of the design, to account for the reversal of the wing movement. The band unwinds half a turn each time the wing reverses, then stops while the wind goes through half a cycle.

BTW, thanks, I needed 30 examples of biomimicry for a HW assignment, this became number 28

 I'm going to try my hand at that!

 Although I only have thick paper I will still try!

(But now that I think about it that might be a problem later on...)

 And I am almost done, I am going to get my camera soon

(Slightly relevant sudden thought: we've had a paper aeroplane contest - why don't we have a flying-model contest?)

Is this an Instructable sort of challenge, or do you just want a video? (Although I won't be able to make one anyways..)

If you do enough to make a video, you've done enough to make a full Instructable!

It's tiny! That's an amazing feat of epic. :D

Epic is what we do best - that's why I laid out the challenge.

First is homework. Then the black and white challenge. Then the usb contest. Then the shop-a-mini challenge. Then I'll see if I can do it. :D

 That is quite a challenge. Perhaps the title should reflect it a little?

 I want to have go.. quite alot involved me thinks.