erik wrote in Fri Aug 04, 2017 6:23 pm:I'm not a big fan of messing with the numbers just because they feel right.
Any change that the center of gravity is too far to the tail for instance?
<function name="aero/moment/Pitch_alpha">
<description>Pitch moment due to alpha</description>
<product>
[...]
<independentVar lookup="row">aero/Re</independentVar>
<tableData> <!-- Du Y -->
1668183 -2.0327
3707224 -1.3432
just inventing numbers is never good;
dany93 wrote in Fri Aug 04, 2017 11:08 pm:Don't you feel that "Messing" is rather strong?
The numbers I propose are neither invented nor "taken out from the hat".
I've already written several times that I do not like cheating with the numbers either.
But in this case the FDM has a problem and I'm looking to find where it can be.
How did you have these numbers? Yongliang Du Thesis? Do you know how to calculate them?
About the center of gravity, its location is rather relative to the AERORP. At first view, I would not change this.
Also, I have observed that the CG location for different loads remains inside the books limits. Which makes me think that the empty CG location is right.
erik wrote in Sat Aug 05, 2017 9:08 am:......but I'm not really sure we already know what the problem exactly is.
.....But after that it is always good to see if you fixed the problem or just covered it up.
The resulting moment is a combination of alpha and elevator deflection
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