Consider the possibility of using two rotating cylinders to replace the conventional wings on an airplane for lift. consider an airplane flying at 150 km/hr through the standard atmosphere at 2,000 m. each "wing cylinder" has a 1.0-m radius. the surface velocity of each cylinder is 20 km/hr. find the length ℓ of each wing to develop a total lift of 40 kn. assume potential flow and neglect end effects.

27.35m

Explanation:

We need first to consider the expression for the lift force, at which is,

Where

= Lift force

= density of air

= vortex strength

However the vortex strength is given by the equation,

Where,

a= 1m, radios of cylinder

, the velocity of cylinder surface.

In the U.S Standard Atmosphere Table, the density of Air to 2000m is

Substituting in first equation we have,

Solving for l, we have,

Therefore the required length of wing cylinder is 27.35m

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg

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