Foo

inputs:

• flight control position

output:

• pitch moment

The position of flight control surface provide an aerodynamic force on the airplane (upward or downward), resulting in a pitch momentum (all acts as if the airplane rotate around its gravity center), and then a pitch rate. Note that this force varies depending on multiple factors (the angle of attack, the air density, the airspeed,...)

Simple integration law

inputs:

• pitch moment

output:

• pitch

It is just a consequence of classical mechanics rules.

Lift curve

Lift coefficient curve (Photo credit: Wikipedia)

Input are:

• angle of attack \(\alpha\)
• speed \(V_x\)

Output are:

• lift

The more you increase the angle of attack, the more you increase the lift (and the drag). The more you increase the speed, the more you increase the lift (and also a little the drag). Given a speed, the variation of lift depending on the angle of attack is called the lift coefficient curve. Note that it is valid for a certain range of angle of attack. If the angle is too high, the aircraft stall, it the angle is too low, the aircraft fall. In both cases, the aricraft cannot fly correctly.

In normal operation, this angle is in the part of the curve where lift increase whane the angle increase.

load factor

[caption id="" align="alignright" width="350"] Load factor n as a function of its angle of bank θ (Photo credit: Wikipedia)[/caption]

input are:

• lift (\(L\))

the output are

• load factor (\(n\))

both are proportionnal. (\(n=\frac{L}{W}\) where \(W\) represent the weight).

Bar

inputs:

• pitch

output:

• angle of attack \(\alpha\)

This is easy to understand: the pitch is the angle between a frame of reference (usually the Earth and therefore the horizon) and the longitudinal axes of the plane, the angle of attack is the angle between the airflow (trajectory in a frame of reference linked to the air) and the wings chord (more or less parallel to the longitudinal axe of the plane), and b