Aircraft Aerodynamic Parameters¶

This file contains the parameters of the aerodynamics model.

The aerodynamics model assumes that the aircraft aerodynamic response can be modeled as the some of a number of airfoils. This method allows for various common modelling approaches such as:

• Fusing the aircraft aerodynamics into one lift, drag and moment airfoil model, ie separate wing surfaces are not modeled and calculated separately. This is not uncommon to the aircraft identification bibliography
• Specifying different airfoils for the main wing and the stabilizer, each with its own aerodynamics model and location on the airframe relative to the Center of Gravity. Their contributions are summed up to provide the overall response of the aircraft.

nWings: The total number of airfoils that the aircraft contains.

CGOffset: The location of the center of lift in terms of the center of gravity, in X/Y/Z body frame coordinates. Negative X means that the CoL is behind the CoG. Positive Y means that the CoL is to the right of the CoG. Negative Z means that the CoL is above the CoG.

mountOrientation: The rotation Roll-Pitch-Yaw (in this sequence) rotation angles which rotate the airfoil from the Body Frame to its actual Airfoil Frame fixture. If the whole aircraft is modelled as a single airfoil, this should be [0.0,0.0,0.0]

chanGimbal: The input channel which controls the airfoil gimbal. Set to -1 for no gimballing action.

gimbalAxis: Selects the axis of the Airfoil Frame around which the gimbal rotation is applied. Available options are: 0 - x-axis, the axis collinear with the wing chord and towards the front 1 - y-axis, the axis collinear with the wing span and towards the right 2 - z-axis, the remaining, orthogonal axis for a right-handed system, perpendicular to the x-y plane and downwards.

gimbalAngle_max: The maximum throw angle (in radians) that the gimbal is providing when given full input.

There are 3 types of airfoil aerodynamic models available. These are selected with the variable aerodynamicsType:(integer) - 0: Selects an empty aerodynamics model, which has no interactions with the surrounding air. Useful for adding a dummy wing on your aircraft, or modeling a rock falling in the void! - 1: Standard Linear Aerodynamics - model with linear relation to its parameters. This is the most common and classic model found in bibliography, which models the reactions of the air using constant linear coefficients to the aircraft states. - 2: Spline Aero - derivative class from 1, which models the lift and drag coefficients as cubic splines. This is useful if you have extracted the lift and drag curves of your aircraft through experiments or FDM simulation but can’t quite capture it in a simple parametric model. Cubic splines offer you the possibility to import your data in full resolution.

double sigmoid = ( 1+exp(-M*(alpha-alpha0))+exp(M*(alpha+alpha0)) ) / (1+exp(-M*(alpha-alpha0))) / (1+exp(M*(alpha+alpha0)));
double linear = (1.0-sigmoid) * (c_lift_0 + c_lift_a0*alpha); //Lift at small AoA
double flatPlate = sigmoid*(2*copysign(1,alpha)*pow(sin(alpha),2)*cos(alpha)); //Lift beyond stall

double result  = linear+flatPlate;

double c_drag_a = c_drag_p + pow(c_lift_0+c_lift_a0*alpha,2)/(M_PI*oswald*AR);