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Thickness


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Thickness

Thickness ratio is the ratio of how THICK the airfoil is at it’s thickest point to it’s CHORD (from leading edge to trailing edge). Typical thickness ratios go from about 0.08 (for a thin, low-drag airfoil) to 0.16 (for a thick, hi-lift airfoil).

 

Drag div mach

This is the Mach number at which compressibility effects become apparent AT ZERO LIFT.0.75 is a good default, supercritical foils should enter a higher number, like perhaps 0.85 or even 0.90.remember this is the Drag Divergence Mach number at ZERO LIFT.X-plane will reduce this number as lift is produced!

 

 

 

Intercept

The lift intercept in the amount og lift the foil puts out at zero degrees angle og attack. .this is the lift when the wing is aimed straight into the wing, and is not pitched up at all, 0 20is a typical value.

 

Slope

The lift slope is the amount of lift the airfoil puts out for each degree angle of attack the wing has on the air. Airfoils almost always have a lift slope of very close to 0.1

 

Lin range

This is the range of angle of attack (from 0 in either direction) that provides a linear increase in lift.

 

Power

Tune this number so the lift curve transitions smoothly into the stall.

 

Maximum

This is maximum coefficient of lift that the airfoil can put out .1.6 is common..

 

Drop

This is an indication of how sharp the stall is... A foil with a sharper stall will lose lift more abruptly when the wing goes to too high an angle of attack. A larger number here will result in a more sudden stall with a sharper drop of the airplane in flight.

 

Power

 

Drop

This is an indication of how much lift is lost after the stall… thick and supercritical airfoils lost little lift, but thin low-drag airfoils lost a lot of lift here.

 

D-min

This is the minimum parasite drag coefficient of the air foil. It probably occurs at an angle of attack close to zero degrees.

 

Min-d cl

This is the coefficient of lift at which the minimum drag coefficient is achieved. Lt is probably close to the lift intercept value you entered above.

 

D alpha=10

This is the parasite drag coefficient of the airfoil at an angle of attack of 10 degrees.

 

Power

This number is theoretically close to 2.0, but you can tune it to fit actual data.

 

Cl location

Some airfoils have a certain angle of attack range where the airflow is laminar, resulting in very low drag. This is the lift coefficient of the laminar flow low-drag bucket, if any.

 

Width

This is how wide the low-drag laminar flow bucker is. in terms of lift coefficient. It is the lift coefficient range across which dragis reduced by laminar flow.

 

Depth

This is how much the coefficient of drag is reduced by laminar flow(if any).

 

Power

This is the power of curvature of the low-drag laminar flow bucket…2.0 might be good guess.

 

Alpha 1

This is the angle of attack at which the airfoil pitching-moment changes…it is almost always the same as the stalling angle of attack, entered below.

 

Alpha 2

…..

 

Cm 1

This is the coefficient of pitching moment at -20 degrees angle of attack. The pitch moment id an indication of how much the airfoil tends to twist up. since airfoils almost always pitch DOWN, this number is almost always negative.

 

Cm 2

This is the coefficient of pitching moment at the pitch-moment change entered above. the pitch moment id an indication of how much the airfoil tends to twist UP. since airfoils almost always pitch DOWN, this number is almost always negative.

 

Cm 3

….

Cm 4

….

Alpha min

This is the negative angle of attack at which the airfoil stalls. The stall is the point at which the airfoil cannot put out any more lift and (usually abruptly) throws in the towel and loses lift.

 

Alpha max

This is the positive angle of attack at which the airfoil stalls. the stall is the point at which the airfoil cannot put out any more lift and (usually abruptly )throws in the towel and loses lift.

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