>Heavily. Clumsily. Slowly. Oh dear :(
>
>However, when I tried to visualise this, a Thought
>occured. A normal bat flaps its wings so fast you
>can't see them. So how slow is "slow"? I tried
>visualising it, I tried flapping in time, I reckoned
>say two seconds from top of stroke to bottom of stroke
>is "slow". That's four seconds for each complete
>stroke.
>
>We've looked at various sizes for the Bat. Let's be
>conservative and say its wings are each 300m long:
>total wingspan a bit over 600m
>
>I seem to remember the flap angle is quite big: the
>wings don't quite meet above and below, but they come
>pretty close to it. Again, let's be conservative and
>say each flap covers 1/3 of the possible angle, not
>the full 1/2.
>
>In each 2 sec up to down, the wing tip covers around
>620m. Average speed of 310m/sec. That's *average* - it
>has to stop at each end and reverse direction.
>
>The speed of sound is 340m/sec. At this scaled down
>and slowed down size, you're getting sonic booms off
>the wingtips with every flap. Yes, I know, physics and
>Glorantha do not mix, but does this give some idea of
>what we mean by "slow"?
I don't have the formulae to work out the figures but on that basis you are also shifting an enormous amount of air, quite enough to blow trees and buildings over. If its wings are beating anything like that fast its progress is going to be marked by a swathe of devastation at least a km. wide and the caravan of bat support staff is going to be some distance behind to avoid being blown away.
I'd go for a flap taking several minutes in normal flight which will still cause a fair wind. It would seem incredibly slow to an observer at a reasonable distance but the wingtip is still travelling at about a metre per second.
-- Donald Oddy http://www.grove.demon.co.uk/
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