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J3 Cub Spins on Takeoff

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J3 Cub Spins on Takeoff

Postby LowFiveJoe » Fri Mar 13, 2020 5:59 pm

Hey All,

All of a sudden the J3 Cub wants to spin (or more accuratley, ground loop) as soon as I release the brakes and crack the throttle. I've flown it previously for numerous hours without this problem. I figured that maybe something got corrupted, so uninstalled/reinstalled 2019.1.1. Still loops. In fact, I can't get it started without "autostart" now. The PA-18 starts just fine, but also ground loops. I can get the PA-18 airborn after spinning wildly in both directions... it takes a while to figure out which direction I'm going once airborn... but the ball swings wildly in either direction. I always recallibrate my pedals and joystick before launching the program, if that helps narrow it down.

Any ideas or help is appreciated.

L5J
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Re: J3 Cub Spins on Takeoff

Postby wlbragg » Fri Mar 13, 2020 10:32 pm

Sorry you're having problems with it. The one in fgaddon shouldn't do that, I think only the one from the development repository on GitHub does it. We changed the back wheel to caster gear. I think there's something wrong in the jsbsim code that causes it to be too loose, so to speak. Either that or we just don't have it adjusted correctly. It's a work in progress.
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Re: J3 Cub Spins on Takeoff

Postby Puffergas » Fri Mar 13, 2020 11:18 pm

Cross wind take offs in aircraft with caster tail wheels can be interesting. Also engine torque. Put the two together and hold on to your hat!
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Re: J3 Cub Spins on Takeoff

Postby Knüppelrührer » Sat Mar 14, 2020 9:08 am

wlbragg,

if it helps to narrow the bug down: All variants (except ski and tricycle) on fgaddon effected running 2019.1.1.
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Re: J3 Cub Spins on Takeoff

Postby LowFiveJoe » Sat Mar 14, 2020 2:52 pm

wlbragg,

It is the fgaddon version. No worries regarding development, I'll keep an eye out for the update. I'm just glad it isn't something I was doing... I'm a plumber when it comes to troubleshooting all things computer. Thanks for the quick replies all.

-Cheers
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Re: J3 Cub Spins on Takeoff

Postby wlbragg » Sat Mar 14, 2020 8:03 pm

I thought I had left fgaddon version alone and change the GitHub version only (added castor wheel). I should probably swap that around if what you say is the case. I think what is in fgaddon needs to be a version that is easier to control.
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Re: J3 Cub Spins on Takeoff

Postby Puffergas » Sat Mar 14, 2020 11:16 pm

I'm a tail dragger fan. If you could point me to where to download, I would give it a spin.
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Re: J3 Cub Spins on Takeoff

Postby LowFiveJoe » Thu Mar 19, 2020 2:35 pm

It's the one in the FGAddon hangar. The DC-3 is a handful as well, but fun to fly.
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Re: J3 Cub Spins on Takeoff

Postby dilbert » Fri Mar 20, 2020 2:38 pm

If the tail wheel was unlocked at some point-castering_-, the FG launcher may now be restarting with it set that way. See if keyboard "l" restores tailwheel locked.
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Re: J3 Cub Spins on Takeoff

Postby Puffergas » Fri Mar 20, 2020 2:52 pm

LowFiveJoe wrote in Thu Mar 19, 2020 2:35 pm:It's the one in the FGAddon hangar. The DC-3 is a handful as well, but fun to fly.


That must be at https://sourceforge.net/p/flightgear/fgaddon/HEAD/tree/, and in the "trunk' folder.

Thanks.
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Re: J3 Cub Spins on Takeoff

Postby Puffergas » Sat Mar 21, 2020 2:01 pm

This version of the J3 crashes FlightGear, so I can not give it a try. I am stuck running an old version of FG so do not worry about FG crashing.
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