Re: Hone and Benton 2007 (their second paper)

[Tim Williams <twilliams_alpha@hotmail.com>]

Michael Habib wrote:

> Being in a tree actually makes launching quite easy, since the animal can 
> use a gravity-assisted >launch.  Essentially, an arboreal pterosaur could 
> simply drop off the tree and then start flapping.  It would hit flight 
> speed quite rapidly using gravity-assisted launch, so the animal need not 
> fall very far.

If I was a pterosaur, and I was dropping out of the tree as a means of 
achieving flight speed - would I open my wings during this 'drop', or would 
I keep them closed?  I was thinking that by keeping the wings folded, I 
would achieve flight speed sooner, since open wings would only create drag 
during the brief descent.  But if my wings are already open during the 
'drop', then they are already positioned for the downstroke.

> Arboreal birds use gravity assisted launches, as do cliff-dwellers like 
> tropicbirds.  Arboreal birds do not require gravity assistance, while 
> tropicbirds (and frigatebirds) often do.

Can you expand on this a bit?

> However, in both cases, the vertical descent prior to reaching cruising 
> speed is quite short.  You can see it if you look for it, however.  Like 
> arboreal birds, a tree-dwelling pterosaur would not require a gravity 
> assisted launch, but it saves energy if you happen to be at a high point 
> already.

So in this situation too, would pterosaur wings be open or closed during the 
vertical descent, prior to reaching cruising speed?

> I hope that helps; definitely an excellent question.

It does; thanks for an excellent answer.

Cheers

Tim

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