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physics of a flapping bird toy
Calica
Registered User regular
Registered User regular
Remember flapping bird mobiles? These things were all over the place when I was a kid:
https://youtu.be/OU3DA-E_MtE
I've been experiencing a little with making them. My PVC and cardboard prototypes work, technically; but they flap very fast and run out of energy very quickly. Not very pretty. The ones I remember seeing in toy stores as a kid would flap more slowly, and you'd get at least two or three good flaps before they gradually returned to equilibrium.
I assume I can get a given mobile to flap a little longer by minimizing wasted energy, but my real question is: how do I slow down the flapping? Bigger wingspan? Heavier materials?
I got far enough googling to know that "harmonic motion" is what I'm after; and while I'm completely down for revisiting calculus if I have to, it would save me some time if somebody here knows the answer and can explain it in words.
https://youtu.be/OU3DA-E_MtEI've been experiencing a little with making them. My PVC and cardboard prototypes work, technically; but they flap very fast and run out of energy very quickly. Not very pretty. The ones I remember seeing in toy stores as a kid would flap more slowly, and you'd get at least two or three good flaps before they gradually returned to equilibrium.
I assume I can get a given mobile to flap a little longer by minimizing wasted energy, but my real question is: how do I slow down the flapping? Bigger wingspan? Heavier materials?
I got far enough googling to know that "harmonic motion" is what I'm after; and while I'm completely down for revisiting calculus if I have to, it would save me some time if somebody here knows the answer and can explain it in words.
+9
Posts
frequency is 1/2pi * sqrt(k/m)
since time=1/ frequecny
T=2pi* Sqrt(m/k)
also this video,
which is in the related of what you linked, says the same thing at ~1:30
e: Also the mass should be near the wing tips, since you get more of a moment there for a given mass.