aircraft:tmd:airfoil
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aircraft:tmd:airfoil [2017/03/02 11:03] – jh | aircraft:tmd:airfoil [2019/07/07 10:35] – [CmAlphaBase] jh | ||
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=== Other Aerodynamic classes === | === Other Aerodynamic classes === | ||
- | [[aerowing]], | + | [[aerowing]], |
===== Angle of attack ===== | ===== Angle of attack ===== | ||
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The attached range is the range of the angle of attack at which the airflow is simulated as attached to the airfoil. It reaches from '' | The attached range is the range of the angle of attack at which the airflow is simulated as attached to the airfoil. It reaches from '' | ||
- | === AttachedCenter === | + | ==== AttachedCenter |
The attached center creates an asymmetric attached center. Using an attribute grater than zero will offset the stall angle towards a greater angle of attack. | The attached center creates an asymmetric attached center. Using an attribute grater than zero will offset the stall angle towards a greater angle of attack. | ||
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{{ Airfoil_Ranges2.png? | {{ Airfoil_Ranges2.png? | ||
- | === ClAlpha === | + | ==== ClAlpha |
The lift coefficient Cl and momentum coefficient Cm increase linear with alpha in the Range of '' | The lift coefficient Cl and momentum coefficient Cm increase linear with alpha in the Range of '' | ||
The gradient of the lift coefficient in respect to alpha is '' | The gradient of the lift coefficient in respect to alpha is '' | ||
- | > Leave it at '' | + | > Leave it at '' |
{{ Airfoil_AttachedRange_ClAlpha.png? | {{ Airfoil_AttachedRange_ClAlpha.png? | ||
- | === Cl0 === | + | ==== Cl0 ==== |
The '' | The '' | ||
> This attribute directly reflects the attitude in which an aircraft flies at high speed (low AOA). It also requires a larger down force from the horizontal stabilizer which increases the drag. It greatly affects the glide ratio. | > This attribute directly reflects the attitude in which an aircraft flies at high speed (low AOA). It also requires a larger down force from the horizontal stabilizer which increases the drag. It greatly affects the glide ratio. | ||
- | > '' | + | > '' |
{{ Airfoil_AttachedRange_Cl0.png? | {{ Airfoil_AttachedRange_Cl0.png? | ||
- | === CmAlpha === | + | ==== CmAlpha |
The gradient of the momentum coefficient Cm is zero for symmetrical airfoils, positive for most typical airfoils that show movement of center of pressure (unstable) and negative for most airfoils with an s-bend (stable), used for flying wings. The '' | The gradient of the momentum coefficient Cm is zero for symmetrical airfoils, positive for most typical airfoils that show movement of center of pressure (unstable) and negative for most airfoils with an s-bend (stable), used for flying wings. The '' | ||
> The '' | > The '' | ||
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{{ Airfoil_AttachedRange_CmAlpha.png? | {{ Airfoil_AttachedRange_CmAlpha.png? | ||
- | === Cm0 === | + | ==== Cm0 ==== |
'' | '' | ||
> With given geometry, incidence and fixed elevator position the '' | > With given geometry, incidence and fixed elevator position the '' | ||
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{{ Airfoil_AttachedRange_Cm0.png? | {{ Airfoil_AttachedRange_Cm0.png? | ||
- | === Cd0 === | + | ==== Cd0 ==== |
'' | '' | ||
> This attribute determines the drag at high speed (low AOA). It effects the glide ratio. | > This attribute determines the drag at high speed (low AOA). It effects the glide ratio. | ||
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> Values can get as low as '' | > Values can get as low as '' | ||
- | === CdAlpha === | + | ==== CdAlpha |
The drag an airfoil produces due to the effective front area and the beginning of the airflow detachment is modeled with the '' | The drag an airfoil produces due to the effective front area and the beginning of the airflow detachment is modeled with the '' | ||
- | > Leave the '' | + | > Leave the '' |
- | === Cd0Base === | + | ==== Cd0Base |
The '' | The '' | ||
=== Resulting total drag === | === Resulting total drag === | ||
- | The total drag produced by an airfoil in the attached range is calculated with a level 2 polynomial function. | + | The total drag produced by an airfoil in the attached range is calculated with a polynomial function |
{{ Airfoil_AttachedRange_CdAlpha.png? | {{ Airfoil_AttachedRange_CdAlpha.png? | ||
- | ==== Flaps ==== | + | ==== AttachedCenterFlap |
- | === AttachedCenterFlap | + | |
The '' | The '' | ||
> Leave it at '' | > Leave it at '' | ||
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> Set a value that is lower to increase the effect of reversed ailerons near stall. | > Set a value that is lower to increase the effect of reversed ailerons near stall. | ||
- | === ClFlap === | + | ==== ClFlap |
'' | '' | ||
> '' | > '' | ||
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{{ Airfoil_AttachedRange_ClFlap.png? | {{ Airfoil_AttachedRange_ClFlap.png? | ||
- | === CmFlap === | + | ==== CmFlap |
'' | '' | ||
> Some aircraft need tremendous amount of negative '' | > Some aircraft need tremendous amount of negative '' | ||
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{{ Airfoil_AttachedRange_CmFlap.png? | {{ Airfoil_AttachedRange_CmFlap.png? | ||
- | === CdFlap === | + | ==== CdFlap |
'' | '' | ||
> Real life flaps always create additional drag when deflected. '' | > Real life flaps always create additional drag when deflected. '' | ||
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> | > | ||
- | <div id = " | ||
==== Table of flap coefficients ==== | ==== Table of flap coefficients ==== | ||
- | > These are just examples | + | Recommended values for the Aerofly |
- | ^ Type of flap ^ ClFlap | + | ^ Type of flap ^ ClFlap |
- | | Plain flap | + | | Plain flap |
- | | Split flap | + | | Split flap |
- | | Slotted flap | 0.8 ... 2.0 | + | | Slotted flap | 2.7 | 0.06 |
- | | Fowler flap | 1.4 ... 3.0 | 0.14 ... 0.3 | -0.73 | + | | Fowler flap | 2.7 ... 3.4 | 0.2 |
- | </ | + | |
- | ==== StallRange and beyond | + | ==== ClAlphaBase |
- | + | ||
- | === ClAlphaBase | + | |
The lift coefficient can be approximated with a sinus function with the wave length of '' | The lift coefficient can be approximated with a sinus function with the wave length of '' | ||
'' | '' | ||
> Decrease this value to get a greater wing drop in a stall and during spins. Lower values increase the dynamics of accelerated stalls and maneuvers. Also decrease CdAlphaBase. | > Decrease this value to get a greater wing drop in a stall and during spins. Lower values increase the dynamics of accelerated stalls and maneuvers. Also decrease CdAlphaBase. | ||
- | === CmAlphaBase === | + | ==== CmAlphaBase |
Follows the same principle as the ClAlphaBase attribute. Usually this value is negative and the airfoil creates a pitch down force when the angle of attack increases beyond the stall angle (stable). The aircraft will pitch down on its own and accelerate again. A positive value is destabilizing. | Follows the same principle as the ClAlphaBase attribute. Usually this value is negative and the airfoil creates a pitch down force when the angle of attack increases beyond the stall angle (stable). The aircraft will pitch down on its own and accelerate again. A positive value is destabilizing. | ||
'' | '' | ||
+ | |||
+ | > The lower the value of '' | ||
{{ Airfoil_Stall_ClAlphaBase.png? | {{ Airfoil_Stall_ClAlphaBase.png? | ||
- | === ClFlapBase === | + | ==== ClFlapBase |
The '' | The '' | ||
> Use the value to regulate the control surface authority in stall or at a high deflection angle. This increases the roll rate for aerobatic airplanes. (See '' | > Use the value to regulate the control surface authority in stall or at a high deflection angle. This increases the roll rate for aerobatic airplanes. (See '' | ||
- | === CdAlphaBase === | + | ==== CdAlphaBase |
The drag coefficient can be approximated with a sin^2 (sinus squared) function that repeats every '' | The drag coefficient can be approximated with a sin^2 (sinus squared) function that repeats every '' | ||
> Decrease the '' | > Decrease the '' | ||
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==== Minimal ==== | ==== Minimal ==== | ||
This will fall back to default values for all attributes. | This will fall back to default values for all attributes. | ||
- | < | + | < |
- | | + | ></ |
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==== All ===== | ==== All ===== | ||
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- | <[string8][Name][AirfoilTip]> | + | < |
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- | < | + | ></ |
- | ></ | + | |
aircraft/tmd/airfoil.txt · Last modified: 2020/09/28 22:44 by jh