Airfoil Modeling

I created this to return the coefficent of lift of an airfoil based on the angle of attack. This represents a general airfoil. As you can see when you run the code, the coef starts dropping off after 15 aoa and drops off incredibly after 20 aoa (stalling). I'm not sure who's interested in stuff like this but I'm trying to be a bit more public with my code. Yes, I have a tendency to be too secretive with techniques...

I'm not sure if there's a plane out there that can fly above 25 aoa. But I'm sure someone will find a plane that does and post it! :p

Global FoilData:Float[] = [0.0, -1.0, -1.5, -1.0, -0.5, 0.0, 0.5, 1.0, 1.5, 1.0, 0.0]

For Local a:Int = 0 To 50
	Print "AOA="+(a-25)+"  Cl="+GetCoefLift(a-25)
Next

End

Function GetCoefLift:Float(degAOA:Float)
	If degAOA > 25 Then degAOA = 25
	If degAOA < -25 Then degAOA = -25
	Local fbase:Float = (degAOA + 25.0) * 0.2
	Local ibase:Int = fbase
	Return FoilData[ibase] + (FoilData[ibase+1] - FoilData[ibase]) * (fbase - ibase)
End Function

Gah! No one is impressed by this!?! I've clearly shown that I deserve to win a nobel prize for aerodynamic research...

Lol croma, im sure id be really impressed if i knew what you're talking about :P
... Im guessing it has something to do with wings?

ps, wots an aoa?

-edit-

ohh. i get it, angle of attack...

Any plane (jet) with more thrust than weight can fly at any aoa they want :)

Post this in a worklog?!

Yep, and AOA is how many degrees the wing is from being perfectly parallel with the oncoming air. AOA can be positive and negative. Positive is when the wing is angled up and negative when the wing is angled down (assuming the aircraft isn't in inverted flight). For every 1 degree of AOA, the coefficient of lift goes up approximately 0.11 (depending on the NACA airfoil). So at 5 degrees AOA the coef of lift would be about 0.55. That number is plugged into the Lift equation like this.

Lift = 0.5 * CoefLift * Density * Speed * Speed * Area

Where Density is the air density in kg/m^3 depending on your altitude (it's about 1.225 at an altitude of 0). Speed is the aircraft speed which is found by getting the magnitude of the velocity vector. And Area is the area of the wing in square meters.

Lift = 0.5 * 0.55 * 1.225 * 100 * 100 * 30

Which would be a Coef of 0.55, density of 1.225, speed of 100 meters per second squared, and a wing area of 30 square meters. These are the basics though, there's a LOT more involved in modeling aircraft physics.

Wings are usually placed at quarter cord to the center of gravity of the airplane. That means that 25% of the lift generated is pushing the nose of the aircraft down (creating a moment (torque)...a rotational force). The tail pushes in the opposite direction and creates stability.

I thought I would add this.

Most us have been taught that about two thirds of the lift generated by a wing comes from the low pressure above the wing as the air speeds up to travel the longer distance. (Bernoulli)
The latest theory is that lift is actually generated by the stream of air clinginging to the surface of the wing that it passes over. So the lift generated by the top surface of the wing is caused by the curvature of the wing deflecting the air downwards. The mass of the downward moving air provides lift in terms of the equal and opposite reaction of Newtons third law.

Just something of interest.