Originally posted by RCadmin
. With an airfoil lift is created because of the different speed at which the air flows over the wing and thus creates lift. Correct me if this is wrong.
Question is with a fully symmetric airfoil wouldn't the air flow over the wing top and bottom exactly the same and thus cause the same forces above and below it? If this was the case how would upward lift be created with a fully symmetrical airfoil?
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The Lift formula is L = CsubL x 1/2 (Vsq. x air mass density x area).
CsubL is Coefficient of Lift or basically Angle-of Attack (AOA).
While lift increases by 50% of the square of the airspeed, it also requires some positive AOA. In any case there must be some outside force to hold a wing in that positive AOA. In conventional aircraft within subsonic convergent airflow that is normally the function of the horizontal stabilizer. Some near imperceptible "up" is applied providing a negative lift of that airfoil (the stab) which then forces the wing into some near imperceptible or more AOA.
AOA is measured between the oncoming airflow versus the wing chord line. Important to notice that a Clark Y (flat bottom airfoil) can produce lift in what appears to be negative AOA -- referencing the bottom of the wing -- as the chordline is actually NOT the bottom but up in the curve of the Leading Edge.
A pilot cannot well control airmass density, other than altitude as Nature determines that. Other than with flaps, etc., a pilot cannot control area as that is a given with his craft. A pilot CAN control AOA of the various lifting surfaces and he can control velocity, the airspeed.
If RCers could actually understand these functions, I predict that 70% of the crashes would not happen.
1. Each surface is an airfoil, and moving/changing that airfoil changes the lift/force arrangements around it. "Lift" is not just a product of only a wing.
2. A certain amount of velocity is required to maintain smooth airflow to produce some desired result. Keep the airspeed up.
3. AOA can be increase to a point that produces turbulent air wherein all force vectors (lift) may well disappear. This point is not a factor of velocity. Yes, you can high speed stall a wing. Done it many times in the 1:1 scale as well as RC.
4. Drag uses the same formula. More speed = more drag and more AOA = more drag. Learn to use the power to maintain glidepaths.
5. Lift is NOT a function of Bank Angle, as the most popular myth in aviation so promotes. Bank angle is a vector function of lift.
If you wish the wing lift function to keep you away from the solid earth, then place the wing to a position to best use the perpendicular function of the lift vector. You may not then need to increase AOA up to the point where it removes itself from the equation. "Stall, Snap, Spin, unintentionally.
Enjoy