Board index FlightGear Support Flying

probable F-14 fdm issue  Topic is solved

Controlling your aircraft, using the autopilot etc.

probable F-14 fdm issue

Postby Solid » Fri Oct 12, 2018 7:55 am

Hi everybody,

i like to fly the F-14 in flightgear. When I updated the last version of the F-14 via QT-launcher (FGFS 2018.2.2), I observed a strange behaviour in flying the model.

When airborne the aircraft started strongly pitching forward. I had always to work against that, even with speeds above 400 kias. The former versions of the f-14 didn´t show that behaviour, they were stable at higher speeds and had only a gentle pitch down at lower speeds.
At first I checked if the joystick is aligned properly, but no issues where found. I tried the F-15, it showed a good flight behaviour, no issues.
Then I tried to uninstall the actual version, but the uninstall button in the qt-launcher does not work. So I deleted the files of the f-14 in "*\Users\User\AppData\Roaming\flightgear.org\aircraft-data" and "*\Users\User\Documents\FlightGear\Aircraft\org.flightgear.fgaddon\Aircraft" and copied an older version (1.3.1) of the f-14 in folder *\Programs\FlightGear 2018.2.2\data\Aircraft".
The older version did work well, no issues.
I reinstalled the new version of the f-14, the issue returned, same behaviour as mentioned above. So I assume a probable problem in the actual fdm of the f-14. :cry:
Does anybody experience similar problems with the actual version of the f-14?

cheers,
Solid
Solid
 
Posts: 39
Joined: Tue Nov 25, 2014 8:25 pm
Location: Niedersachsen, Germany
Callsign: Solid
Version: 2018.2.2
OS: Win 10

Re: probable F-14 fdm issue

Postby it0uchpods » Fri Oct 12, 2018 1:59 pm

You may need to trim the aircraft. This behavior is normal. Pitch trim exists specifically to counteract this :)



Kind Regards,
Josh
it0uchpods/WTF411

FGFS Aircraft Developer
Lead Programmer at it0uchpods Design Group
Download High Quality Aircraft from it0uchpods Hangar
User avatar
it0uchpods
 
Posts: 3567
Joined: Tue Oct 06, 2015 12:51 pm
Version: 2018.2.1
OS: Windows 10 x64

Re: probable F-14 fdm issue

Postby Solid » Sat Oct 13, 2018 11:55 am

Thank you for your quick reply, Josh!

I tried to work against the pitch with trim. It worked on higher trim values at higher speed, but not on the lower speed band. Even the autopilot couldn´t manage to hold the altitude; the aircraft always continued to descent. I wouldn´t have post this as an issue, if the behaviour of the actual model isn´t that much different as that of the previous one. I´m not convinced that the issue discribed is desired by the developer.

Kind regards,
Achim
Solid
 
Posts: 39
Joined: Tue Nov 25, 2014 8:25 pm
Location: Niedersachsen, Germany
Callsign: Solid
Version: 2018.2.2
OS: Win 10

Re: probable F-14 fdm issue  

Postby Richard » Sun Oct 14, 2018 7:10 pm

Solid wrote in Fri Oct 12, 2018 7:55 am:Hi everybody,

i like to fly the F-14 in flightgear. When I updated the last version of the F-14 via QT-launcher (FGFS 2018.2.2), I observed a strange behaviour in flying the model.

When airborne the aircraft started strongly pitching forward. I had always to work against that, even with speeds above 400 kias. The former versions of the f-14 didn´t show that behaviour, they were stable at higher speeds and had only a gentle pitch down at lower speeds.


Firstly thanks for flying this model.

Secondly, yes there was a fault that I'd recently introduced in the aerodynamic model that was fixed yesterday (2018-10-13) in FGAddon (so update from the launcher).

The problem was a badly defined table for pitch moment due to flaps, which in effect because of the bad definition was applying pitching moment for flap deployment even when the flaps were not deployed.
Richard
 
Posts: 618
Joined: Sun Nov 02, 2014 10:17 pm
Version: Git
OS: Win10

Re: probable F-14 fdm issue

Postby Solid » Mon Oct 15, 2018 9:13 am

@Richard:

Thanks a lot for your fast response and your immediate work on the aerodynamic model. I made a testflight ( ;-) ) today in the early morning and the issue seems to be solved .
Furthermore I´d like to thank you very much for giving the flightgear community such formidable aircraft to fly with. I love flying the F-14 (did I mention that earlier?) :-D ...

Kind Regards,
Achim
Solid
 
Posts: 39
Joined: Tue Nov 25, 2014 8:25 pm
Location: Niedersachsen, Germany
Callsign: Solid
Version: 2018.2.2
OS: Win 10


Return to Flying

Who is online

Users browsing this forum: No registered users and 4 guests