Quote:
Originally Posted by VaSteve
I'm on vacation and someone is flying around in a biplane. Got me thinking. Does the additional wing create additional lift? Even so, Doesn't it interfere with the lift the first wing in creating? I know there's triplanes too... I've never seen one with 4... There has to be a point where the weight outweighs the added benefit. Right?
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You'll need to understand something about fluids first. Lift is simply differential pressure between the upper surface of the wing and the lower surface. Faster moving fluids create lower pressures. If the wings are spaced far enough apart, there is no interference.
A bi-plane and tri-plane allow shorter wings to create lift at the same speed. Mono-planes usually need higher speeds to create enough lift to fly.
For aerobatic planes, the shorter wings allow the plane to rotate about their central axis more quickly. This improves maneuverability. A Fokker tri-plane could rotate and bank more quickly than their counter parts. However, what you loose is stability. Longer wings are more stable than short wings.
Seahawk is correct that a biplanes disadvantage is parasitic drag from the interwing structure. This could be overcome by using monoplane type internal structure and eliminating bracing. The main thing is to understand what you are trying to achieve and design for that. Nothing is for free.