The use of Aerodynamic Forces and Moments from Aerospace Blockset

Hi,

I'm currently working on simulating an aircraft and woulud like to implement friction forces on it. I have a block that calculates the friction coefficients, I've set both the gravity and pressure center to the origin the frame of my aircraft (a simscape multibody object). For the dynamic pressure, i'm using the Dynamic Pressure block from Aerospace Blockset. But, when I try to use the Aerodynamic Forces and Moments block my aircraft behave anormaly (it start spining and get too much speed).

So my question is : How to use the block ? Should my center of pressure not be fixed ?

Thanks for your answer.

[Ashok]

Could you share the relevant (simplified) files to reproduce the issue?

Answer 1

[Ashok]

Hey @ARCHI XXI COULSON,

In real flight, the center of pressure changes with the angle of attack. However, for smaller angles of attack, within the range of [-15, 15] degrees, assuming a constant center of pressure should yield decent results. For instance, in the HL-20 simulation example linked below, the center of pressure is treated as a constant value: 

https://www.mathworks.com/help/releases/R2023b/aeroblks/hl-20-with-flight-instrument-blocks-and-visualization-using-unreal-engine.html

Additionally, the relative positions of the center of gravity and pressure depend on the aircraft and are usually not the same. Properly positioning the center of gravity and pressure should potentially resolve the issue.

I believe this will be of use!