Gentlemen,

This same brainteaser has often been mentioned to full-scale student and licensed pilots. Even though it is ultimately a physical laws question and answer, RC and full-scale pilots often appreciate the physics behind the answer as can be seen by the size of this thread. In the aviation example it goes like this:

Consider a 747 (but any aircraft will do) loaded to its maximum payload weight in birds. Later when the airplane is in cruise flight all the birds take to flight inside the aircraft at the same time. Will the aircraft now be lighter and suddenly accelerate and climb because all the birds are in the air in the cabin?

As many here have pointed out similarly, the answer is that the aircraft's weight is unchanged, such as the weight of the jar with the flies is, (and therefore the pilots will not have to wrestle an out of trim aircraft whenever any number of the birds decide to fly around in the cabin).


See my new post in the aerodynamics forum for a new twist on this, titled "another brain bender"