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HDG autopilot on Cessna 550 Citation II doesn't work

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HDG autopilot on Cessna 550 Citation II doesn't work

Postby simlu » Sat Jul 18, 2020 5:57 pm

Hello,

im very new to this nice hobby. So exuse my question. I downloaded the Cessna 550 aircraft from the menu, did autostart engine and pressed HDG on the autopilot panel. But the aircraft doesn't respond to this (i have set the HDG bearing, autopilot is set to ON, LED indicators are also on). Is there maybe a hidden switch i didnt see or what is the reason why HDG doesn't work, also the ALT doesn't work. Looks like the autopilot isn't active (the device says its active).

thx for help.
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby WoodSTokk » Sat Jul 18, 2020 10:24 pm

If you mean the device bellow the HSI and the first button in the upper row lit, then the AP is OFF!
You can see this by looking at the panel between the seats on the middle console.
There is the AP panel with 3 buttons. 'AP ', 'YD ' and 'LOW BANK'. If the 'AP' button is dark, the AP is off.

Hint: you can activate the AP at 500 AGL and above. If you lower then 500 AGL the AP will disengage automatically!
The AP isn't very good, so please make sure your speed is 180kts or more. If you are slower, the AP can't control the aircraft nicely (it starts to swing).
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby simlu » Sun Jul 19, 2020 9:33 pm

Thanks! the AP button between the seats was off and the LED indicator infront is ON if the autopilot is deactivated :D
Another question: while landing, after touching the ground at about 120 kts, the plane is automatically steering to left. Rudder is set to neutral, throttle 0%. Its hard to stay in a line and not leave the runway. This aircraft has two engines, it should drive straight or do i some mistakes?
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby WoodSTokk » Mon Jul 20, 2020 2:44 am

I have some times also the problem on landing. I think the aircraft is too sensitive on crosswind.
Will investigate it if i have enough spare time.
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby simlu » Mon Jul 20, 2020 3:05 pm

Just found an example video (5y old) of the described behaviour.
https://www.youtube.com/watch?v=Ft-UYlSNo9A

Also while take off the aircraft seems to drift fast.
Beside these things i like this aircraft :)
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby danielHL » Mon Jul 20, 2020 6:44 pm

yeah, the sideways sliding on the runway is due to high sensitivity on crosswind. Please note that the weather dialog is lying to you if you use advanced weather and the scenario "fair weather". There is more than 3 knots wind speed here, usually. If debugging, always check in the property tree under /environment for real wind data.
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Re: HDG autopilot on Cessna 550 Citation II doesn't work

Postby WoodSTokk » Mon Jul 20, 2020 10:18 pm

I think the Citation is beyond the possibilities of YaSim.
YaSim expect the center of gravity at around 25% relative to the MAC.
The Citation is in real nose heavy, therefor the CG is located at 35%-40% relative to the MAC.
For YaSim this is too far aft so the nose wheel loose friction if you pick up speed.
I dont see any property to teach YaSim that this CG is correct for a nose heavy aircraft.
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