Re: flocking

["Norton, Patrick" <Patrick.Norton@state.me.us>]

Jim C. wrote:

>Reduced mass with a constant wingspan results in reduced induced drag   
for a given airspeed, and consequently reduced power required (and muscle   
mass
required) for any given airspeed. This is a well-known, well documented
aspect of long-distance bird migration.<

I agree, reduced mass translates into reduced power requirement for any   
given airspeed.  But I lost you when you said that airspeed would "tend   
to increase" under those conditions.  Airspeed would increase _if_ the   
bird maintained a constant power output as its mass decreased (which   
could occur during the time it was metabolizing fat for energy).  But at   
some point after muscle begins to be metabolized, there is simply not   
enough muscle left to maintain that power output.  At that point, power   
output would decline and airspeed would decrease--or at best stop   
increasing.

>During those last four hours, his average airspeed was considerably   
faster than the best instantaneous speed he was capable of achieving at   
his greater mass upon start of the flight.<

But certainly there were an enormous number of variables that could   
explain that performance which could not possibly have been controlled   
during that event.