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Bob Marton

Take off roll issue

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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....


Robert Marton

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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.

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Captain Kevin

nGsKmfi.jpg

Air Kevin 124 heavy, wind calm, runway 4 left, cleared for take-off.

Live streams of my flights here.

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


 

 

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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.


Dan Downs KCRP

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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!

 

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Bob Scott | AVSIM Forums Administrator | AVSIM Board of Directors
ATP Gulfstream II-III-IV-V

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22 minutes ago, w6kd said:

Single-engine operations in a 747??  Yikes!

 

This is a 777 topic Bob.


Dan Downs KCRP

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6 minutes ago, downscc said:

This is a 777 topic Bob.

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

 


Bob Scott | AVSIM Forums Administrator | AVSIM Board of Directors
ATP Gulfstream II-III-IV-V

System: i9-10900K @ 5.2GHz on custom water loop, ASUS Maximus XII Hero, 32GB GSkill 3600MHz CAS15, EVGA RTX3090 XC3 Ultra
Samsung 55" JS8500 4K TV@30Hz,
3x NVME 2x SATA Samsung SSD, EVGA 1KW PSU, 1.2Gbps internet
SoundBlaster XFi Titanium, TOSLINK to Yamaha RX-V467 HT Rcvr, Polk/Klipsch 6" bookshelf spkrs, Polk 12" subwoofer, 12.9" iPad Pro
PFC yoke/throttle quad/pedals with custom Hall sensors, Coolermaster HAF932 case, Stream Deck XL button box

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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

 


Robert Marton

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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

 

 


Bob Scott | AVSIM Forums Administrator | AVSIM Board of Directors
ATP Gulfstream II-III-IV-V

System: i9-10900K @ 5.2GHz on custom water loop, ASUS Maximus XII Hero, 32GB GSkill 3600MHz CAS15, EVGA RTX3090 XC3 Ultra
Samsung 55" JS8500 4K TV@30Hz,
3x NVME 2x SATA Samsung SSD, EVGA 1KW PSU, 1.2Gbps internet
SoundBlaster XFi Titanium, TOSLINK to Yamaha RX-V467 HT Rcvr, Polk/Klipsch 6" bookshelf spkrs, Polk 12" subwoofer, 12.9" iPad Pro
PFC yoke/throttle quad/pedals with custom Hall sensors, Coolermaster HAF932 case, Stream Deck XL button box

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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.


Xander Koote

All round aviation geek

1st Officer Boeing 777

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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?


Robert Marton

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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?


 

 

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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. 


ki9cAAb.jpg

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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.


Robert Marton

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