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Why does my airplane runs off the track when taking off?

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Why does my airplane runs off the track when taking off?

Postby Zequinha » Wed Mar 22, 2017 1:47 pm

Hi folks,

I am puzzled as to why every single aiplane I choose (Piper J-3 Cub, Carreidas 160, etc...) instead of following a straight line while taking off, it starts to exhibit weird motion, turning left or right and falling off the track before I get the chance of lifting off the ground. I know it is not a problem of the joystick because this weird behaviour also happens when i use only the keyboard.

FlighGear 2017.1.1, even though this problem also happened to me with previous versions.

Any ideas why this is happening?
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Re: Why does my airplane runs off the track when taking off?

Postby FlugHund » Wed Mar 22, 2017 2:07 pm

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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Wed Mar 22, 2017 2:36 pm

Awesome! Thanks for the info!

Now, in the case of jet aircraft, e.g. carreidas, could the crosswinds explain the deviation from the track? If so, how do I counteract this, as turning right/left won't actually do anything!
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Re: Why does my airplane runs off the track when taking off?

Postby Johan G » Wed Mar 22, 2017 3:46 pm

It depends a bit on what controls you are using, but in general crosswinds can be easier to handle if you have separate a separate rudder axis (either using a twist joystick or rudder pedals), but with "some" training people have been able to use other means as well.

I have collected some good video lessons on real life crosswind technique in these two forum posts in the topic Interesting videos:


Note that while these techniques are demonstrated with GA* aircraft, they pretty much apply to all sizes of aircraft.

* GA = General Aviation, loosely meaning smaller propeller aircraft owned by flight clubs/schools or individuals.

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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Wed Mar 22, 2017 4:38 pm

Thanks once again for all the info.

I will try to set up a separate control for the rudder!
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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Mon Mar 27, 2017 12:52 pm

Indeed controling the rudder makes a big difference! :)
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Re: Why does my airplane runs off the track when taking off?

Postby Clive2670 » Mon Mar 27, 2017 5:17 pm

A good joystick to maybe consider buying is the Thrustmaster HOTAS X see this link for info: http://www.thrustmaster.com/products/tflight-hotas-x The joystick has a twist axis for controlling the rudder and numerous programmable buttons. The twist function makes a very useful function for controlling "your" plane during crosswind landings and take-offs. Shop around though (Ebay, Amazon, ETC) as prices vary a lot! In my view this is a really versatile joystick that is fully programmable to cover virtually all the main things in the cockpit right from the cessna through to fighter jets and upto the 747! I use it daily in the 777-200LR, A lot easier than the keyboard when you have to be doing several actions at the same time during take-off or landing. Hope this is of help to you?
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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Wed Mar 29, 2017 9:19 pm

Thanks Clive2670! I also have a thrustmaster joystick but a more basic one: http://www.thrustmaster.com/products/usb-joystick

It's not ideal to control the rudder, I think. But I will try and see if I can program any of the top buttons to move the rudder!
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Re: Why does my airplane runs off the track when taking off?

Postby Johan G » Thu Mar 30, 2017 6:11 pm

There are some rudder keys on the keyboard, though not all that intuitive to some. IIRC the keys corresponding to the control stick, rudder pedals and toe brakes interprets a quicker press as a smaller deflection change and a longer press as a larger deflection change. In any case you could have a look in $FG_ROOT/keyboard.xml for inspiration, where $FG_ROOT is the data directory in your FlightGear installation. There is a lot of Nasal code embedded in and also included into that configuration file. See also $FG_ROOT/Nasal/controls.nas to see some of the included Nasal functions.

tl;dr: Control input can be extremely flexible in FlightGear. :wink:
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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Thu Aug 03, 2017 8:27 am

Thanks guys,

But I realised I don't need this degree of realism and I want to turn off wind/crosswind effects or propeller torque for the propeller airplanes. I want to be able to take off aligned with the track out-of-the-box. How can I turn these effects off?
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Re: Why does my airplane runs off the track when taking off?

Postby legoboyvdlp » Thu Aug 03, 2017 10:08 am

We don't really have an option to do that, as it is assumed that the user is willing to fly with this degree of realism. It is built-in to the simulator, as far as I know.
Is there a specific problem that causes you to be unable to use the rudder?
Many thanks,
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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Thu Aug 03, 2017 11:11 am

oh, no specific problem at all. It is just a matter of personal preference. I use FG as a game rather than a realistic simulator so for me, it would be great if I could adjust the realism settings of the simulation, from a gamers perspective.
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Re: Why does my airplane runs off the track when taking off?

Postby wkitty42 » Thu Aug 03, 2017 2:05 pm

then you might want to look at a flying game instead of a simulator like flightgear...

remember, you can play games in a simulator but a simulator is not a game ;)
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Re: Why does my airplane runs off the track when taking off?

Postby Zequinha » Mon Aug 07, 2017 9:43 am

wkitty42 wrote in Thu Aug 03, 2017 2:05 pm:then you might want to look at a flying game instead of a simulator like flightgear...

remember, you can play games in a simulator but a simulator is not a game ;)


Simulators in general should allow for different degrees of complexity and realism so the researcher can debbug and analyze the results of the simulation.

Having said this, I personally think it would be a valuable option. At least to compare the trajectory of the plane with crosswinds to that obtained in their absence, thus evaluating their effect.
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Re: Why does my airplane runs off the track when taking off?

Postby Thorsten » Mon Aug 07, 2017 11:09 am

Having said this, I personally think it would be a valuable option.


Then I suggest you get coding, because personally I think my time is wasted dumbing down the simulation I've worked hard to make realistic, and I've heard similar statements from other core developers.
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