digital DATCOM forces and moments coefficient Clq or CLq ?

Hello,

I'm currently using DATCOM to create an aerodynamic model of an C172. In the DATCOM doc the CLq is reffered as a pitching derivative coefficient (here, a force). But according to the digital datcom help (link: http://www.mathworks.com/help/aeroblks/digitaldatcomforcesandmoments.html?s_tid=srchtitle) the CLq is the matrix of rolling-moment derivatives due to pitch rate (here, a moment).

What assumptions are made to use the CLq coefficient, which should be on the Fz axis, as a rolling moment coefficient??

In advance, thank you.

Alex

Answer 1

[Akash]

Hi,

I'm assuming you are using MATLAB 2016a or an earlier version and are getting an incorrect aerodynamic coefficient is being read while importing your DATCOM data into Simulink.

This is a known issue with MATLAB 2017a and earlier where the Digital DATCOM Forces and Moments block incorrectly interprets the DATCOM derivative CLQ as Clq (rolling-moment derivative due to pitch rate) instead of CLq (lift force derivative due to pitch rate). This is a link to the External Bug Report : https://in.mathworks.com/support/bugreports/details/1544961

This issue has been fixed in R2017b. If upgrading is not an option, please follow the workaround in the provided link.

Thank you,

Akash