Greenfinger said...
How come aircraft can fly inverted ? (upside down)
Why do paper airplanes fly ? (no airfoil)
Angle of attack ?
The aircraft that fly inverted eg Extra 300's and so on have a SYMMETRICAL Airfoil which allows them to generate the same amount of lift as they normally would when they are inverted.
How do they fly at all if they have have equal or no lift on either side of the wing i hear you say?
well thats where angle of attack comes into it, angle of attack is the angle between the wings chord ( line between wing Leading edge or LE and the trailing edge or TE ) and the relative airflow. when you get a positive angle the airfoil generates lift.
when they are flying dead level they dont produce much lift and rely allot on there very powerful engines.
the optimum angle of attack for efficient flying is approximately 4 degrees but it depends on the airfoil type. Most airfoils stall at about 16 degrees. they stall because the boundary layer can no longer "stick" to the wings surface and it breaks away thus laminar flow is no longer there and no lift is generated.
The power to weight ratio of a stunt plane is significantly great then that of a cessna 152 or something like that.
which leads us to why can those stunt planes fly on there side for a while...
Well its because of those 600hp engines up the front there, its called flying on Knife Edge, its mostly the engines thrust holding up the plane but a little of the lift comes from the side area of the Fuselage generating a little lift.
2 years and an A+ in aeronautics at school and 3 years of flying RC aircraft helped answer these questions.
I hope it helps!
) it is all about a net turning of the gas (air flow) and conservation of energy. The airfoil shape (and Bernoulli's principles) has only a little to do with lift and probably more to do with effeciency and aerodynamics on planes. Although I suspect the foil shape has more influence at lower air speeds - ie sails and kites.
