🚀 go-pugleaf

>Actually, as someone has already stated, birds do not fly because their
>wings push down. They fly because air flows forward over their wings and
>their wings are shaped such that it has a longer path over the top of the
>wing than the bottom. Therefore, the pressure above the wings is lesser
>and lift is created. Therefore, I'm going to stick my neck out and say
>that when all the birds are flying in the truck or the airplane, their
>weight is at least decreased.
>Shawnee
>
>> The lift for each bird
>> must come from somewhere and the somewhere eventually has to be the bed of
>> the truck.
>>
IF the birds develop a power pack which provides forward thrust OR if they
are gliding OR in a breeze THEN the Bernoulli component of lift may be
relevant to their flight.  The situation which was described did not
specify any of  those conditions.  The birds were taking responsibility for
their own lift through the action of their wings.  The rest follows,
through the chain of logic, that the lift for each bird must come
ultimately from the bed of the truck and through that to the ground.
David Bailey                              !  Faculty of Science &
Technology,
University of Western Sydney, Nepean            !  P.O. Box 10, KINGSWOOD  2747
Phone (047) 360 429  Fax (047) 360 713    !  Australia