Re: pterosaur take-off analog

[Erik Boehm <erikboehm07@yahoo.com>]

> they cannot keep themselves up just by flapping once gusted into the air.

Right, if the wind goes from 10 mph to 25, and back down to 10, its not going 
to be able to simply flap and stay up.
But if the wind is blowing 25 mph steady state, and the ptero has a 15 mph 
stall speed, it doesn't need to accelerate once up at all, merely flap enough 
keep itself from decelerating below 15 mph airspeed.

If the wind is highly variable, launching in a gust rather than a lull, is a 
bad idea. 

> They could takeoff in a dead calm, even in today's atmosphere.
JimC

I guess my context didn't make that clear. I already thought they could.
"If they needed wind to takeoff, they would be lunch far too often,"

My point was that what was most important was the "dead-calm" launch,
as I have a hard time imagining them able to survive if they couldn't, and its 
the most technically demanding mode of achieving flight, whereas launching into 
a wind is technically much easier.

I just think it could be so easy they could just spread their wings, maybe from 
a quad position, kind of like when one does a pushup fast enough to clap their 
hands together.
Just a little push with the arms, then quickly spreading them, and maybe they 
could be airborne into a smooth 20 mph wind, and then flap to slowly start 
moving forward (relative to the ground) and gain altitude.

And I still think they *could* just lay on their belly, and with sufficient 
dihedral to get their wings off the ground enough to get airborne. Not to say 
they would actually do it in practice.