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Re: JSBSim Piper J-3 Cub

Postby wlbragg » Fri Aug 18, 2017 2:30 pm

dany93 wrote in Wed Aug 16, 2017 5:40 pm:3 - @wlbragg: I see that the active Lift_alpha curve in FGAddon is Du Y's one. Is it your choice? It is more comfortable but I'm afraid that it is not realistic. The USA-35B curve should be more appropriate (in the hope that it is correct, several sources agree well enough on it).

Sorry, I've been distracted as of late. I left the table Du Y for now until we hopefully get some input from Erik.

I'll have a look at (1) shortly.
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Re: JSBSim Piper J-3 Cub

Postby erik » Fri Aug 18, 2017 5:05 pm

Oh I thought it was already settled to go with the USA-35B curve.

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Re: JSBSim Piper J-3 Cub

Postby wlbragg » Sat Aug 19, 2017 3:52 am

I thought it was already settled to go with the USA-35B curve.

Good, wanted to make sure you were OK with it.

Done.
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Re: JSBSim Piper J-3 Cub

Postby Bomber » Sat Aug 19, 2017 8:02 am

Guys,

the USA-35B curve is a specific airfoil curve... the Du Y's one is a planes curve which takes into account the airfoil, fuselage and h-stab.

IF you use a specific wing airfoil curve, your equations for lift would have to reflect this and I'd have to redo the elevator lift curve table to take into account the h-stab portion of the tail.

It can be done... but you are getting more and more towards the way I do my flight models... so be careful what you wish for.
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Re: JSBSim Piper J-3 Cub

Postby dany93 » Sat Aug 19, 2017 10:14 am

Interesting, I hadn't thought at this. But it makes the choice still more difficult. And what about the lift from the fuselage if we need it?...
I've been puzzled when watching the attitude (fuselage pitch angle) at high airspeed with USA-35B. Nose down -6 to -7 deg near 100 kts by using aero/alpha-wing-rad (as it should be done) instead of alpha-rad.
Or is it a conception in order to have the lowest drag near 60 kts?
Last edited by dany93 on Sat Aug 19, 2017 10:20 am, edited 1 time in total.
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Re: JSBSim Piper J-3 Cub

Postby Thorsten » Sat Aug 19, 2017 10:20 am

Within 5 minutes spent with google, I learned of the existence of at least three research papers on the J-3 aerodynamics (with fulltext however not accessible outside the university network).

Has anyone tried writing to the authors of these yet?
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Re: JSBSim Piper J-3 Cub

Postby Bomber » Sat Aug 19, 2017 2:50 pm

Please provide links to these papers. I have access.
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Re: JSBSim Piper J-3 Cub

Postby Thorsten » Sat Aug 19, 2017 6:17 pm

To the intranet of a Malaysian university? You surprise me...

Anyway, googling 'piper j-3 aerodynamics ' was all it took...
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Re: JSBSim Piper J-3 Cub

Postby legoboyvdlp » Wed Nov 01, 2017 4:07 pm

Hi there.
I have a bit of an issue. Only the YASIM Cub works --> the rest all say that they can't find the <aero>!
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Re: JSBSim Piper J-3 Cub

Postby wlbragg » Wed Nov 01, 2017 4:23 pm

Hum, I just installed the fgaddon version from the qt-launcher and it worked fine.. I wonder if you don't have some garbled aircraft cache. Can you try to remove the j3cub aircraft cache and see if that clears it up?
In windows I think it is located at something like
c:/Users/%username%/AppData/Roaming/flightgear.org/aircraft-data/J3Cub.xml

If that doesn't work we're going to have to do some investigating as this is a first, no one else has mentioned it so I have a feeling it may be something local to your setup?
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Re: JSBSim Piper J-3 Cub

Postby legoboyvdlp » Wed Nov 01, 2017 4:42 pm

Sure. That's fine!
Should help...
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Re: JSBSim Piper J-3 Cub

Postby wlbragg » Wed Nov 01, 2017 4:49 pm

I found some issues that appear to be unrelated to the error your getting, but may be causing it anyway. I am almost finished cleaning it up and testing. I'll push it to fgaddon shortly.
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Re: JSBSim Piper J-3 Cub

Postby wlbragg » Wed Nov 01, 2017 5:07 pm

OK, I pushed some corrections. This could have potentially caused an error like the one you saw even though it was unrelated to the message you see in the log. It could have been the catalysis.

Please let me know if this fixes it and thank you for bring it to my attention.
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Re: JSBSim Piper J-3 Cub

Postby legoboyvdlp » Wed Nov 01, 2017 5:14 pm

OK, great :)
Will try shortly.
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Re: JSBSim Piper J-3 Cub

Postby legoboyvdlp » Wed Nov 01, 2017 5:37 pm

I did git pull on your GitHub repository.
Code: Select all
input:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Main\options.cxx:2165:aircraft = PA-18
flight:3:G:\Jenkins\workspace\Windows-release\flightgear\src\FDM\JSBSim\JSBSim.cxx:249:  aero does not exist (you may have mis-typed the name).


Also:

Code: Select all
general:4:G:\Jenkins\workspace\Windows-release\install\msvc140-64\include\simgear/props/tiedpropertylist.hxx:59:Failed to tie property /controls[0]/flight[0]/slats[0]
general:4:G:\Jenkins\workspace\Windows-release\install\msvc140-64\include\simgear/props/tiedpropertylist.hxx:59:Failed to tie property /controls[0]/flight[0]/spoilers[0]
general:4:G:\Jenkins\workspace\Windows-release\install\msvc140-64\include\simgear/props/tiedpropertylist.hxx:59:Failed to tie property /controls[0]/flight[0]/speedbrake[0]
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/orientation/side-slip-rad'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/orientation/beta-deg'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/orientation/roll-rate-degps'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/orientation/pitch-rate-degps'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/orientation/yaw-rate-degps'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/accelerations/pilot/x-accel-fps_sec'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/accelerations/pilot/y-accel-fps_sec'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/instrumentation/slip-skid-ball/indicated-slip-skid'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/surface-positions/elevator-pos-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/surface-positions/left-aileron-pos-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/surface-positions/right-aileron-pos-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/surface-positions/rudder-pos-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[0]/steering-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[1]/steering-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[2]/steering-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[0]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[1]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[2]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[19]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[20]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[21]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/gear/gear[22]/compression-norm'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[23]/z-position'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[24]/z-position'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[25]/z-position'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[4]/z-position'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[5]/z-position'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/sim/alarms/stall-warning'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/controls/switches/master-avionics'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/hazards/icing/wing'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[23]/WOW'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[24]/WOW'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/fdm/jsbsim/contact/unit[25]/WOW'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/controls/switches/master-bat'.
systems:3:G:\Jenkins\workspace\Windows-release\flightgear\src\Aircraft\flightrecorder.cxx:266:FlightRecorder: Recording non-existent property '/controls/switches/master-alt'.
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