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Aeronautical Engineering/Squirrel Tail Propulsion ?

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Question
Hello Mr. Janus,

Please view the slow motion video below.  

The slow motion video (Squirrel Tail Propulsion) was taken in my backyard. Please note the comment by Steve Harris, mammal expert.
  "Your footage, however, does seem to show the animal accelerating in mid-air, though we donít know the rate of acceleration or what it is gaining in distance."          
  
http://www.discoverwildlife.com/blog/qa-squirrel-tail-propulsion
http://www.youtube.com/watch?v=qCxHENrcjIM

My question to you is this:

Is there any way to analyze the slow motion video to determine if the squirrel is, in fact, "accelerating in mid-air".  

Thank you very much for your time.  

Bill Earl

Answer
Well not exactly in my area of expertise, but I did watch the video and will offer my opinion...
I believe that aerodynamically there is very very little the squirrel can gain from the movement of his tail...  that said, it looks to me like the squirrel is using his tail and the law of conservation of angular momentum to make a final adjustment for his landing....  this is much the same thing as a cat (you know the old saying that a cat will always land on his feet)...  well they use their tail motion to orient their body (in observation of conservation of angular momentum)...  flip your tail one way, your body flips (rotates) the other way...

I believe that is all that the squirrel is doing here..  Very little aerodynamic force could be generated by the tail of a squirrel (even though it's quite fluffy and has a fairly large planform area)....

Thanx,
mj

Aeronautical Engineering

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Mark Janus

Expertise

I can answer questions about aerodynamics (high speed and low speed), internal fluid flow, computational methods (CFD, some design, etc.)

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25+ Aerospace Engineering, University Professor

Organizations
Mississippi State University AIAA SIAM

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AIAA SIAM

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PhD Aerospace Engineering

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