Flying bat model (and other ornithopter designs)

Yesterday we learned that bats “row” through the air scooping great gobs of air and thrusting it downward. The bat ornithopter shown here (Fig. 1) actually flies more like a pterosaur.

If you haven’t seen this radio-controlled flying bat model (Fig. 1), I think you’ll find it quite impressive. The wings control the lift and thrust. The hind limbs control direction.

Figure 1. Radio-controlled bat video on YouTube.

Figure 1. Radio-controlled bat video on YouTube. This is a basic ornithopter, like the toy shaped like a bird. The hind limbs tilt one way or the other and this is all that is needed to steer this flapping aircraft. 

Earlier we looked at a YouTube video of an attempt by the Stanford group spending half a million dollars to create a flying pterosaur with a life-life skull, fur and several servos operating various wing movements. Ultimately it failed.

Perhaps they should have started small, like this bat-like ornithopter, which simply flaps and steers — and it flies very well. With this sort of early success, the Stanford pterosaur design could have evolved with small variations in wing shape, at each stage experiencing success at their ultimate goal: flapping flight.

Note the lack of camber in the wings chord. Ornithopters like this create camber while flapping as the air fills both sides of the wing on both the downstroke and upstroke. Each load is dumped posteriorly by the relatively loose trailing edge to create thrust.

Note the hind limbs acting as horizontal stabilizers. They are moveable and extend laterally. This is a configuration first suggested by Jim Cunningham and promoted here.

Bat designer, Kazuhiko Kakuta, has a Facebook page with several other videos showing several other models, including a nice Pteranodon.

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