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Table of Contents
Aerofuselage
Objects from the aerofuselage
class create lift and drag based on their geometry. In knife edge flight the aerofuselage creates the greatest amount of lift compared to all other aerodynamic objects. Like an airfoil the aerofuselage has a lift coefficient, in fact two even. One for the side forces (y-direction) and one for the up/down forces (z-axis). It also has a drag coefficient for each of the axis.
Other Aerodynamic classes
Stations
Like an aerowing an aerofuselage
is divided into at least two sections with a maximum count of 16. Each section (station) has an X, Y and Z position, a height and width and a shape parameter assigned in the appropriate arrays: StationX
, StationY
, StationZ
, StationWidth
, StationHeight
and StationShape
. Each of these array must contain the same number of values. For readability it is recommended to align the sections values to form a grid pattern in the TMD code (example code below). The shape attribute is an approximation of the fuselages shape for a cross section at the given station x position. It can be either round 0
or rectangular 1
. Round shapes will produce other flight behavior than rectangle shapes.
Coefficients
An aerofuselage instance can have up to 6 different coefficients:
- 3 drag coefficients, one for each axis:
Cdx
,Cdy
andCdz
- 2 lift coefficients for y and z
Cly
andClz
- 1 moment coefficient
Cm
Level flight
Cdx
The Cdx
parameter is the drag coefficient in flight direction. When the air only comes from the front this is the only coefficient that shows any influence on the flight behavior of the aircraft. A higher coefficient results in a higher drag produced by the fuselage and therefor reduces the distance the aircraft can glide. A higher value also affects the maximum velocity of the aircraft because the drag increases while the thrust remains the same. The Cdx value must be positive for a realistic physics simulation.
Typical values are between0.3
and0.05
. Gliders have less, aircraft with rougher surfaces tend to have higher values.
Flight in high angle of attack
Clz
The Clz describes the lift of the fuselage created by the increase of the angle of attack. With a larger value the fuselage contributes a significant amount of the total lift of an aircraft.
1.2
is a good value to start with
For aerobatic aircraft: Clz should be set lower than the Cly if the fuselage is taller than wide. Otherwise rolling circles or loops tend to oscillate upwards each time the wings are somewhat level compared to the knife edge attitude where the fuselage creates almost all of the lift.
This value greatly affects the rotation speed of the knife edge spin
Knife Edge flight
Cdy
Cdy
is the drag coefficient of the fuselage for a sideways stream of air (y-axis). The greater the value the more drag the fuselage creates when in a side-slip condition. With a higher value the required thrust or the sink rate increase while in side-slip. Its value must be positive for a realistic physics simulation.