I would like to know where the -1.2004 comes from. I assume the -1.8 is taken from multiple current FG aircraft implementations?
Not really. That was my guess by trial and possibly error (shame ) or rather an estimated adjustment, although not blindly.
I see -1.12 (C172P), -1.16 (Seneca II), -1.8 (DR400), -2 (Tecnam P92 echo). I'm wondering if the C172P would not have the same problem (Cmalpha = -1.8 while it is at -0.65 for Cessna 182
Not really
although not blindly
Thorsten wrote in Sun Aug 13, 2017 7:34 pm:Sorry, what is the issue that's currently bugging you?
Thorsten wrote in Sun Aug 13, 2017 7:34 pm: Do you want to know the relation between moments and forces? I thought you know that.
wkitty42 wrote in Sat Aug 12, 2017 10:00 pm:F10->File->Quit is a good and proper exit as is using ESC to get to the exit dialog and selecting the [OK] button... i, and i'm guessing others, understood your using the 'X' comment to mean the 'X' in the top right corner where the maximize and minimize buttons are when running in non-fullscreen mode...
you should try it... it is beautiful without those frames and their decorations... easy to do via SHIFT-F10 IIRC... it toggles fullscreen mode on and off... i use ALT-TAB to switch to other tasks on the same desktop and can also switch to one of eight other desktops but that's something my OS provides as long as CTRL-F1-8 aren't eaten by something else
it0uchpods wrote in Sun Aug 13, 2017 10:25 pm:True -- but that takes so long and I am extremely impatient
it0uchpods wrote in Sun Aug 13, 2017 10:25 pm:Then why doesn't FG do something like MSWord has where when you close, he asks for confirm, and shutdown properly in this way...??
it0uchpods wrote in Sun Aug 13, 2017 10:25 pm:Ehh. Full screen Flight Sim never appealed to me. I quite like this thing at the bottom of my screen:
Force = qbarpsf x S0 x dCL/dalpha x alpha
moment = qbarpsf x S0 x dCL/dalpha x alpha x arm0
moment = [qbarpsf x Sw x cbarw] x [S0/Sw] x dCL/dalpha x alpha x [arm0/cbarw]
is the common set of quantities for the FDM calculation,qbarpsf x Sw x cbarw x alpha
moment = [qbarpsf x Sw x cbarw] x alpha x factor
factor = [S0/Sw] x [arm0/cbarw] x dCL/dalpha
<function name="aero/moment/Pitch_alpha">
<description>Pitch moment due to alpha</description>
<product>
<property>aero/qbar-psf</property>
<property>metrics/Sw-sqft</property>
<property>metrics/cbarw-ft</property>
<property>aero/alpha-rad</property>
<!-- possible comments -->
<value>-1.30</value> <!-- dany, quick calculation -->
</product>
</function>
<function name="aero/moment/Pitch_elevator">
<description>Pitch moment due to elevator</description>
<product>
<property>aero/function/qbar-induced-psf</property>
<property>metrics/Sw-sqft</property>
<property>metrics/cbarw-ft</property>
<property>fcs/elevator-pos-rad</property>
<!-- possible comment-->
<value>-1.08</value> <!-- dany, quick calculation -->
</product>
</function>
The flight model uses dummy engines and prop so as to add no forces and as such this is purely a glide and aerodynamics test...
So you’ll need to start at 10000ft and 50kts and you’ll see that without touching any of the controls the plane is really quite stable. It doesn’t go off into a spiral dive.... so far so good.
After a while it’ll settle down and you can see the LIFT2DRAG value of 14.7 in the /fdm/jsbsim/aero/forces directory of the properties.
At this point you’re using the original elevator deflection code... and you can see the force and moment values in the relevant properties folders.
If you change the property /fdm/jsbsim/aero/elevator_test to a value of 1... you will be using my elevator deflection code..
You will see no difference with no elevator deflection.
Lift_elevator_test
Pitch_elevator_test
Are the values that are now being used and you can compare these with the originals
Lift_elevator
Pitch_elevator
<switch>
<default value="aero/moment/Pitch_elevator"/>
<test value="aero/h-stab/moment-lbsft">
aero/elevator_test EQ 1
</test>
<output>aero/moment/Pitch_elevator_test</output>
</switch>
<function name="aero/moment/PITCH">
<sum>
<property>aero/moment/Pitch_propwash</property>
<property>aero/moment/Pitch_alpha</property>
<property>aero/moment/Pitch_elevator_test</property>
<property>aero/moment/Pitch_damp</property>
<property>aero/moment/Pitch_alphadot</property>
<property>aero/moment/Cmdf</property>
</sum>
</function>
dany93 wrote in Wed Aug 16, 2017 6:40 pm:Hi Wayne, Simon.
I did Simon's tests.
Your display of calculated values in the properties are very convenient.
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