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MD11 not behaving properly

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MD11 not behaving properly

Postby Flight876 » Sat Feb 25, 2017 12:07 pm

Hey guys
When I tried taking off in the MD11 today, I noticed that the aircraft really doesn't want to stay on the runway it sometimes moved off to left, and sometimes the plane would move off to the right of the runway, and when I attempt to lift the nose up, the aircraft doesn't even get off the ground. and sometimes the aircraft get's off the ground, but get's extremely unstablized, to the point where the plane would either banks off to the right or the left and just crash into the ground. What should I try doing in order to get the MD11 to behave properly whilst on takeoff and in mid flight?
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Re: MD11 not behaving properly

Postby Johan G » Sat Feb 25, 2017 1:18 pm

I see that you have been here a while so I apologize if I am a bit basic. Also, I rarely, if ever, fly airliners.

Flight876 wrote in Sat Feb 25, 2017 12:07 pm:[...] the aircraft really doesn't want to stay on the runway it sometimes moved off to left, and sometimes the plane would move off to the right of the runway [...]

What controls do you have (in essence keyboard, mouse, joystick etc.)?

It seems like you had a bit of "wathervaning", in essence that a crosswind was pushing your vertical stabilizer away, turning your nose into the wind.

If you are not using autocoordination it might help a bit to try roll into the wind with the ailerons early in the takeoff roll (but remember to gradly neutralize during the rollout so they are neutral before takeoff ;) ).

Flight876 wrote in Sat Feb 25, 2017 12:07 pm:[...] when I attempt to lift the nose up, the aircraft doesn't even get off the ground. and sometimes the aircraft get's off the ground, but get's extremely unstablized, to the point where the plane would either banks off to the right or the left and just crash into the ground.

Did you look up the stall (Vs) or rotation airspeed (V2) for your takeoff weight and configuration (in essence flap settings).

Weight, configuration and density altitude* can change the stall and rotation airspeeds a lot.

From the lateral instability it seems you are very close to or actually are stalling. Also remember that pitch primarily affects airspeed and throttle primarily affects altitude. ;)

* Probably not that important in this case, density altitude (DA) is dependent on pressure altitude and temperature. Hot air have less density and will give less lift. This is particularly important when departing from high altitude airports on hot afternoons. I have collected some videos explaining DA here.
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Re: MD11 not behaving properly

Postby tikibar » Sat Feb 25, 2017 7:20 pm

Sounds like you're taking off in a crosswind and rotating too early and/or don't have the flaps set correctly. Flaps should be 15, and Vr at MTOW is around 175 kias, or about 160 if you're carrying less weight.
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Re: MD11 not behaving properly

Postby Flight876 » Sun Feb 26, 2017 1:15 am

Johan G wrote in Sat Feb 25, 2017 1:18 pm:I see that you have been here a while so I apologize if I am a bit basic. Also, I rarely, if ever, fly airliners.

Flight876 wrote in Sat Feb 25, 2017 12:07 pm:[...] the aircraft really doesn't want to stay on the runway it sometimes moved off to left, and sometimes the plane would move off to the right of the runway [...]

What controls do you have (in essence keyboard, mouse, joystick etc.)?

It seems like you had a bit of "wathervaning", in essence that a crosswind was pushing your vertical stabilizer away, turning your nose into the wind.

If you are not using autocoordination it might help a bit to try roll into the wind with the ailerons early in the takeoff roll (but remember to gradly neutralize during the rollout so they are neutral before takeoff ;) ).

Flight876 wrote in Sat Feb 25, 2017 12:07 pm:[...] when I attempt to lift the nose up, the aircraft doesn't even get off the ground. and sometimes the aircraft get's off the ground, but get's extremely unstablized, to the point where the plane would either bank off to the right or the left and just crash into the ground.

Did you look up the stall (Vs) or rotation airspeed (V2) for your takeoff weight and configuration (in essence flap settings).

Weight, configuration and density altitude* can change the stall and rotation airspeeds a lot.

From the lateral instability it seems you are very close to or actually are stalling. Also remember that pitch primarily affects airspeed and throttle primarily affects altitude. ;)

* Probably not that important in this case, density altitude (DA) is dependent on pressure altitude and temperature. Hot air have less density and will give less lift. This is particularly important when departing from high altitude airports on hot afternoons. I have collected some videos explaining DA here.

I have a Attack 3 joystick I use it to fly the plane(Like lifting the nose, etc, you get what I mean) and there's also a throttle control on the joystick, and I use the keyboard for basic function, like setting the flaps and starting the aircraft up.
And also, which position on the flaps is position 15? Can't seem to figure that out
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Re: MD11 not behaving properly

Postby tikibar » Sun Feb 26, 2017 3:31 am

2 clicks on the ] key.
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