Does using wings with different wing loadings work the same as a swing wing, without swinging the wing?

Question

Does using wings with different wing loadings work the same as a swing wing, without swinging the wing?

Was just wondering: we need the maximum co-efficient of lift at slower speeds at takeoff, but a much smaller co-efficient of lift at cruising speed.

For a triplane, wouldn't you want the top wing for flying and the other wings just for takeoff?

In other words:

you could make the top wing, a classic unsymmetrical wing like a NACA2415, set at around 5 deg angle of incidence, where I believe these airfoils are most efficient.

The other wings could be a wing with a high wing loading, like a high speed laminar foil, like the canard of a velocity, set at a incidence of 0 deg during straight and level flight.

In that way, the lower wings provide no lift, but also no induced drag ( drag due to lift) during straight and level flight, just like a classic tail airfoil.

During takeoff, you would have to rotate early prior to takeoff, ( like the Concorde) to get an angle of attack for all wings.

Say all 3 wings are the same size and you size your wings to get an overall wing loading of 7psf, which means you can land slow and short, but during cruise you would only be using 1 wing, so your effective wing loading is a very efficient 21psf. If it's gusty out, you could always land long and fast , using all 3 wings. So this would be like a swing wing, without the complexity of actually swinging the wing.

Is this correct, at least conceptually?

Answer 1

For a triplane, wouldn't you want the top wing for flying and the other wings just for takeoff?

No.

1. Form drag is proportional to dynamic pressure and frontal area. By varying the lift coefficient between the planes you are not doing much to the frontal area, so the form drag is roughly the same.

2. Induced drag is proportional to square of lift and inversely proportional to square of span and dynamic pressure. By generating three times more lift with one of the wings, you are making it produce more than tree times the induced drag.

   It is not all the nine times the basic equation suggests, because the efficiency is still significantly reduced by interference when all the wings are producing lift, but it is still worse, and it is worse whenever the lift is not distributed uniformly (maybe the interference makes a slight increase in the middle wing desired, I am not sure here, but it won't be big difference).

So the configuration is not better than evenly distributed lift in any flight regime.