>> I know that the real planes fly because of its curved wings.
>> However, paper airplanes don't have such curved wings.
>> How can it fly? Where does the lifting force come from?
| Well, speaking as someone who sprained his back lifting shuttle
| documentation--everybody knows an airplane flies when the weight
| of its documentation equals or exceeds the weight of the airplane.
| Therefore a paper airplane flies because it's self-documenting.
The Galileo probe, however, was the first spacecraft to be outweighed
by its own *environmental impact report*, according to the people I
talked to at JPL this winter. (The EIR was ~ 1 million pages; it made
me wonder if they'd chopped down enough trees to require a meta-EIR.)