This bug popped up a couple of weeks ago on my FSX system and I can't pin down the cause. I use a Saitek Pro Flight Yoke, TQ, and rudder pedals. Also have a Saitek stick for some planes, which I can use to experiment and eliminate problems with the yoke/pedals. I use FSUIPC4 to calibrate everything. I have specified more than adequate null zones at the center of aileron, rudder, and elevator controls, applied filters, and disabled transient spikes. While accelerating the Cessna 172SP for takeoff (weather is nil, no wind), a little right rudder is needed to counteract the left yaw present in a single piston engine plane such as the C172 or Maule Orion. Is it necessary to maintain some right rudder during the climb (700 FPM) to cruise? I'm a simmer and don't know if this is necessary in the "real" world. Once in the air I release right rudder pressure and the plane starts banking very slowly to the left. If I keep hands off it eventually stabilizes at approx 15* bank, and would keep making large circles forever. If I flip on only the AP master switch the wings level off. Flip AP master off and the bank begins again. Strange, eh? Once I'm at cruise and have throttled back to 2,300 RPM the bank doesn't happen! I can take my hands (and feet) off the controls and fly straight and level. I used to fly with Autorudder active and never noticed this tendency. But I'm ready for more realism so have deactivated Autorudder. Now I'm dealing with this undesired left bank. I tried Autorudder again and the bank goes away. Does anybody have a clue for me? The fact that it only banks left leads me to suspect that I need to keep right rudder pressure until cruise altitude.Thanks, MH

That's why small aircraft have trim tabs on the rudder and one of the ailerons, so you can fly "hands off" under you usual cruise ower setting. Somewhat larger aircraft (as in twins) often have explicit aileron and rudder trims, in addition to the elevator trim. See a hardware module from Go-Flight with all three trims ()plus gear and flap switches) here. If you don't want to go the hardware route, you could re-center your aileron and rudder axes via FSUIPC, or also assign aileron and rudder trim to keys. Cheers, - jahman.

check the fuel in the left and right tank. That can also be a reason for the left bank.(more fuel in the left tank) Furthermore FSX exaggerates lateral imbalance which means that if you put only the pilot in the seat in the loadout screen without a copilot, this can cause a noticable imbalance as well.

Could be the ailerons. That left yaw is due to the prop wash. Can you recaliberate your sticks ?

It can also be due to the realism settings being set full right as that accentuates any prop torque (which will be left or right depending on the rotation of the propeller), or any control for that matter.The other thing to remember is that FSX likes to see all axes have the sensitivity set full right and the null zone set full left initially and you can then tweak these according to your personal preferences.RegardsPeterH

It's a gyroscopic effect created by the torque of the propeller. The propeller rotates clockwise, and following Newton's law "For every action, there is an equal and opposite reaction," rotational force is generated in the counterclockwise direction. This counterclockwise rotational force manifests itself in a roll to the left. The strength of the force will vary with your power settings, i.e. at higher power settings the force will be stronger, and at lower power settings it will be weaker. The roll you describe is occurring because of your increased realism settings. It's a factor real world single engine piston pilots deal with every time they fly. It can be dealt with by trimming the aircraft before flight, but the pilot will still be required to use manual control inputs to counter this force as the power is varied. Hope this helps.

Strange, eh? Once I'm at cruise and have throttled back to 2,300 RPM the bank doesn't happen! I can take my hands (and feet) off the controls and fly straight and level.

... Climb trim is going to be different from cruise trim. - that's why you don't have the effect once you've levelled off. FSX is working properly!

Yes, in my C152 there is no rudder trim, only a manually adjustable tab on the rudder section itself. Its not that great....roll correction usually required at higher power settings regardless.

Is it necessary to maintain some right rudder during the climb (700 FPM) to cruise?

That's what I was taught :) And I got a stern warning when I didn't.On that first turn to cross wind take care to keep the ball centered.Or you'll get a second stern warning ;)

check the fuel in the left and right tank. That can also be a reason for the left bank.(more fuel in the left tank)Furthermore FSX exaggerates lateral imbalance which means that if you put only the pilot in the seat in the loadout screen without a copilot, this can cause a noticable imbalance as well.

I would check this first. The 172 has cross feed as the default fuel setting so it's probably not a fuel imbalance, but as mentioned if you have a pilot in the left seat as the only load then your aircraft will bank to the left (something I've never encountered in a real aircraft but a definite annoyance in FSX).

I just discovered (as jahman said) that there are manual rudder and aileron trim tabs, and I would give that a try except - I have finally discovered what seems to be the key (and which several of you have pointed out). While climbing at full power with TO elevator trim, the left bank happens (I understand the propeller torque effect). Once I level off and center elevator trim, the drift is gone, even if I continue at full throttle - stays straight and level. So I suspect that changing either the manual rudder or aileron trim would prevent me from hands off flying once I'm at cruise. Both tanks have same amount of fuel and it doesn't seem to matter if I'm alone or have a passenger in the right seat. I've recalibrated too many times to count and nothing has improved. I just disconnected my Saitek yoke, TQ, and pedals, and plugged in my Saitek AV8R stick. No change, so... apparently not a hardware problem. And re: peterhayes' reply, since I'm using FSUIPC to control all axes, there are no realism sliders that I'm aware of that could cause a problem. Have I misunderstood something? So my conclusion, based on all the responses is that I can expect the left roll while climbing at full throttle and TO trim, but need to counteract it the same way I counteract it during takeoff roll - a little right rudder. If I continue that until cruise, I'll be fine. Only one further question - probably directly related to FSX and not evident in real-world flying. During the climb, while banking left, if I activate AP (Z keyboard key) but without HDG, ALT, NAV, or APP activated, the ailerons operate - in response to the AP button - just enough to level the wings. If I deactivate AP, the left bank resumes. It doesn't make sense to me that the AP button on its own would change the position of any control surface. Is that an FSX anomaly or would that happen in the real world too? Thanks for all the suggestions folks,MH('67 390 Mustang Fastback 4-speed, would rather have a 428 Cobra - just to hear the sound)

>Once I level off and center elevator trim, the drift is gone, even if I continue at full throttle - stays straight and level Torque, p-effect etc.. are most noticable at low speed and if you are climbing/descending. Planes are normaly rigged to fly straight and level at cruise speed and attitude.Any trim input increases drag and it's cruise where you want the least amount of drag of course.A few prop planes have the whole vertical stabilizer mounted at an offset angle and/or use an asymmetrical wingsection to achieve a zero trim cruise condition. >It doesn't make sense to me that the AP button on its own would change the position of any control surface Engaging the AP without any other mode in many planes engages the basic attitude functions of pitch and bank hold. The AP does of change the position of the flight controls to maintain the present pitch and bank angle.

Thank you bstolle. Your reply gave me some information I already knew about, but contained further very helpful comments and details that I didn't know about. Thanks again for your very clear and complete reply. MH

Hey how about the prop wash ?

I have _exactly_ the same problem, and it was driving me nuts. Besides takeoff, this was mostly noticeable when approaching a runway. I performed an ILS approach and turned off the AP 200 feet AGL, the 172 was perfectly lined up, but then it started banking left, and I had to turn slightly right and apply some pressure on the right pedal (Have Saitek Pedals) to counter the effect. This only occurs if the auto-rudder is off, and the realism settings sliders are currently set to the middle exactly. So what's the most optimal way to resolve that while not sacrificing the realism settings?