|MadSci Network: Physics|
Hi Nikos, That's a good question. There is a simple relationship between airfoil lift and air density, which is related to altitude: L = CL ρ V2 A / 2 Where CL is the coefficient of lift, ρ is the air density, V is the airspeed, and A is the area of the airfoil. CL is a dimensionless number that is measured for a given airfoil shape and angle of attack. ρ is a function of altitude, which is explained in detail here. Basically, lift decreases as altitude increases. For this reason, high altitude aircraft must fly faster or use larger wings to generate the same lift as those at lower altitudes. The best discussion of lift distribution I have found is here. Madhu - blog
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