Re: pteros have lift-off

[David Peters <davidpeters@att.net>]

Just so I understand, What is the number for the CG height at rest?  
And the number for the CG height above THAT number is 3.34 meters for  
Q northropi based on an isometrically scaled up Q sp? Is there a  
multiplier you use for determining height of apogee based on resting  
CG height?

> >  Do you start at the zero point measuring acetabulum or glenoid  
> > height? And how many of these height units does your favorite  
> > pterosaur have to achieve in the first leap?
>
> I use the cg, but glenoid works as a marker, too.  For a 200kg  
> Quetz northropi launching at 30 degrees from the horizontal, I get  
> a cg elevation (or glenoid elevation) of 3.34 meters from the  
> resting line (i.e. its a somewhat larger number taken from the  
> beginning of the unload).  Impressive, but hardly supernatural.   
> And more than enough for clearance on the downstroke.
>
> > How fast do your calculations say a few particular pteros can run  
> > before they get to the femur breaking point?
>
> Running speed to break point relationships are rather tricky,  
> actually, but ballpark 6-7 m/s for a big azhdarchid, perhaps,  
> assuming it could even run bipedally at all.  Nyctosaurus comes in  
> very wimpy, of course; probably under 4 m/s.  But to be honest,  
> I've mostly worried about bipedal leaping ability, because that's  
> much more telling than running speed for several reasons (see below).

I can see your interest in the last hop after a running take-off. Or  
a bipedal hop vs. a quad hop. Absolutely.

If pteros ran at the speed of living lizards capable of bipedal  
locomotion, that would be a paltry 2.5 to 4 m/s or 5.7 to 8.8 miles/ 
hour. I looked through your paper and did not see a specific estimate  
for minimum flight speed. Is there a number we can compare?

David Peters
davidpeters@att.net