Airfoil vs. Flat Wings? Answered
I built a model airplane which is rubber band powered. At first I built the wing of the shape of an airfoil and I can assure you that the shape was perfect. When I tested the plane, it just kept on going and going straight with very high speed but never took off. I guessed that the weight was more. So, after removing the weight it still didn't take off.
I then used just a flat piece of cardboard for the wing with a slight tilt, so that it would deflect the air downward and produce the upward thrust. I then tested the plane, and even though the wing was heavier than the airfoil one and the plane moved on the ground slower than before maybe due to increased drag and weight.....the plane took off just beautifully just after a few seconds of launch!!!
I don't know what was the reason, the airfoil shape was perfect, the surface area of the both wings was same. I guess that flat wings produce more lift.....I doubt that the airfoil produced any lift at all, or maybe they require significantly higher airflow over them than flat tilted wings to produce a fair amount of lift...can you tell me what could be the reason?