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Table of Contents
Propeller
A propeller rotates around a spinning driveshaft which acts a torque onto the propeller. In the Aerofly FS 2 there are two kinds of propellers: the propeller
class implements a propeller behavior in a rotating reference frame, attached to a rotating PropellerBody (rigidbody) whilst an aeropropeller
uses a stationary Body and rotates itself. In all default Aerofly FS 2 aircraft only the propeller
class is used.
Attributes
Body and EngineRotationSpeed
A propeller
object will use the velocity of its Body
(rigidbody) and the EngineRotationSpeed
from the driveshaft and calculate a thrust value from that and a torque value to create that amount of thrust. It then adds that force and torque onto the Body
which will accelerate/decelerate the body and speed it up or slow it down over time.
R0, X0, Y0, Z0
The position of the propeller hub is defined by the R0
position vector.
X0
is the local forward,Y0
is the local left,Z0
is the local upwards direction.
In the example of the Extra 330 LX below the propeller is slightly angled to the right (side thrust).
Airfoil
The same airfoil class is used for the aerowing and the propeller class. Using the properties of the AirfoilPropeller
it is possible to fine-adjust the torque and thrust produced by the propeller. A typical propeller airfoil is designed for a lift coefficient of about 0.5
.
Radius
The Radius
of the propeller class is the physical radius of the actuator disk in meters. When converting from inches to meters simply multiply the radius in inches by 0.0254 m/inch
. The radius of the propeller is of course half the diameter, which is usually given in the specifications.
Radius = 0.5 * Diameter
Pitch
The pitch of a propeller is roughly the blade angle at 75% of the radius. The pitch is the distance in meters that the propeller corkscrews through the air in one full rotation (geometrically). If a propeller pitch is given in inches multiply that figure by 0.0254 m/inch
to convert it to the meter length unit used here.
With a given blade angle (alpha) and a radius ® the blade pitch is calculated to:
Pitch = 2 * pi * r * tan(alpha)
PitchControl
The name is self-descriptive here. A input can be given to change the pitch of a propeller. That way a constant speed propeller can be controlled by a governor, reversed into beta or reverse thrust or feathered.
AspectRatio
The AspectRatio
of a propeller
is a factor that can be used to influence the rotationspeed - velocity relation ship. Physically it describes the ratio of the blade radius and the mean chord length of a blade.
Example Code
Simple Fixed Propeller
<[string8][object][propeller] <[string8][Name][Propeller]> <[string8][Body][PropellerBody]> <[string8][EngineRotationSpeed][DriveShaft.GetRotationSpeed]> <[string8][DamageOnCrash] [Engine.Damage]> <[tmvector3d][R0][0.0 0.0 0.0]> <[uint32][NumberBlades][2]> <[float64][Radius] [1.00]> <[float64][Pitch] [1.50]> <[string8][PitchControl][0.32]> <[float64][AspectRatio] [7.00]> <[float64][CutOut] [0.20]> <[float64][LateralDragCoefficient] [0.005]> <[float64][LateralForceCoefficient][1.000]> <[float64][TorqueReduction][0.0]> >
Extra 330 LX - Constant Speed Propeller
<[string8][object][propeller] <[string8][Name][Propeller]> <[string8][Body][PropellerBody]> <[string8][Airfoil][AirfoilPropeller]> <[string8][EngineRotationSpeed][DriveShaft.GetRotationSpeed]> <[string8][DamageOnCrash] [Engine.Damage]> <[tmvector3d][R0][1.9004 -0.0037 0.0064]> <[tmvector3d][X0][0.990279 -0.069798 0.000000]> <[tmvector3d][Y0][0.069798 0.990279 -0.000000]> <[tmvector3d][Z0][0.000000 0.000000 1.000000]> <[uint32][NumberBlades][3]> <[float64][Radius] [0.99]> <[float64][Pitch] [1.80]> <[string8][PitchControl][Governor.Output]> <[float64][AspectRatio] [9.00]> <[float64][CutOut] [0.20]> <[float64][LateralDragCoefficient] [0.005]> <[float64][LateralForceCoefficient][1.000]> <[float64][TorqueReduction][0.0]> >