Hi I recently upgraded to P3Dv4. I have not set up a yoke/joystick yet, and reverted to my old habit of steering via keyboard commands. When I taxi, I generally stay right down the middle, but when I line up on a runway and press TOGA, the aircraft drifts off the side of the runway. I dont know if this is a PMDG normal issue, a P3D issue or operator error, but hope someone might have some insight that could keep me from taking on the part time job of mowing the grass with those beautiful landing gear....

First two things I'd check are your engine instruments and flight control indications to see if either the engines are producing different levels of thrust or you have a control surface not centered.

Thank you Kevin, I will give that a try this afternoon.

Weather settings? If you're using live weather then it would strange if pulls the same everytime, though.

Be sure you are derating the takeoff power of those beasts out on the wings if you are anything less than MTOW.  There is an excess of thrust available for single engine operations, which means there is too much thrust most of the time.  Use flex and derate.

14 minutes ago, downscc said:

Be sure you are derating the takeoff power of those beasts out on the wings if you are anything less than MTOW.  There is an excess of thrust available for single engine operations, which means there is too much thrust most of the time.  Use flex and derate.

Single-engine operations in a 747??  Yikes!

 

22 minutes ago, w6kd said:

Single-engine operations in a 747??  Yikes!

 

This is a 777 topic Bob.

6 minutes ago, downscc said:

This is a 777 topic Bob.

Oops.  Had three different windows open...  :-)

 

6 hours ago, Captain Kevin said:

First two things I'd check are your engine instruments and flight control indications to see if either the engines are producing different levels of thrust or you have a control surface not centered.

Ok Kevin, I tested your theory, I opened up the panel which shows control surface position, and everything there was right down the middle. I also kept an eye on the engines and they were also symmetrical. I am going to see if there is another culprit here,  and that being P3D keyboard sensitivity regarding ailerons. I think this might be playing a role due to the fact that when I first opted to use the keyboard for taxi, there was excess movement when wanting to turn slightly, but when I  adjusted those sliders, I got some relief.

I will post if that solves it for the benefit of the 5 other enthusiasts who still rely on the keyboard for such purposes.

Thank you again tho for the good advice, it was a very good approach.

Rob

 

One other thing to try...turn down the P-factor effects in the realism settings. 

I've not tinkered with it in P3D, as I am not one of those lucky five keyboard commandos, but as I recall, in previous MSFS versions, P-Factor actually results in a horribly unrealistic amount of yaw on a turbine aircraft in the sim.

Cheers

 

 

It is the crosswing acting on the rudder of the aircraft. It is not noticable during taxi. But during takeoff, it requires quicker action. Same as in real life.

Update.

I placed the 777 on the active runway at Eglin with no data  input into FMC. I set flaps 15 on short range fuel amount, applied full throttle, and in this case, the aircraft followed the centerline down the runway. It did not drift to the right or left.

Any last thoughts on this behavior?

10 hours ago, Bob Marton said:

Update.

I placed the 777 on the active runway at Eglin with no data  input into FMC. I set flaps 15 on short range fuel amount, applied full throttle, and in this case, the aircraft followed the centerline down the runway. It did not drift to the right or left.

Any last thoughts on this behavior?

Different airport that before? Different weather settings? As suggested above, have you ruled out crosswinds catching the rudder?

You placed it in the runway so it is correctly lined up. If you taxi onto the runway, especially using keyboard control, it might look lined up but a small heading error could send you off the runway edge during the takeoff roll. 

Andreh, winds calm. I tried it on a different airport, and then went back to the original airport where first noted, LatinVFR KMIA. Same outcome, no drift when just applying throttle compared to drift after FMC programmed.

Kevin, I will take your suggestion into consideration, the weird part is that it doesnt drift if I did not program the FMC.

I appreciate all of your recommendations, there must be a solution right under my fingertips, i guess im in for some trials.