How's your physics knowledge?

[Ed W]

...'cause I need someone to 'splain this to me!  I think the left-hand fan is pushing just enough to overcome drag and the right hand one provides lift.  The paper airplane settles into the 'sweet spot' in between.  But that's as far as my reasoning goes.

[RecycleMichael]

I believe your assessment is correct.

The right fan provides the Bernoulli effect...Derived by Daniel Bernoulli (see Bernoulli family), the principle explains the lift of an airplane in motion. As the speed of the plane increases, air flows faster over the curved top of the wing than underneath. The upward pressure exerted by the air under the wing is thus greater than the pressure exerted downward above the wing, resulting in a net upward force, or lift.  - from answers.com

The left fan provides push and air flow at a force that equalizes the pressure exerted downward on the wing. 

[waterboy]

I'm surprised that the turbulence caused by the two air streams meeting would allow the plane to sit still at all.

[TheArtist]

Kewl