Reducing turboprop torque effect in flight_model.cfg

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1

Hi,

I am trying to adjust certain flight dynamic effects in aircraft’s flight_model.cfg section [FLIGHT_TUNING], in this case using the Black Square TBM 850.

In particual I want to reduce the in-flight tendency of left banking caused by high propeller torque.

As per the SDK documentation and my very limited flight dynamics knowledge this should be possible through the following settings:

[FLIGHT_TUNING]
gyro_precession_on_roll = 1
gyro_precession_on_yaw = 1
p_factor_on_yaw = 1

However reducing all of the floating values from 1 via 0.2 down to 0.01 does not have any actual effect at all.

Does anyone have an advice if I am overseeing limitations in these values or even looking at wrong items?

Thanks,

Stefan

2

It works on some aircraft but not on others. Its as if some developers can bypass this section of the CFG. Having said that, I can successfully reduce the excessive torque on most aircraft.

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3

@sgaviation Wouldn’t it be easier to simply use rudder trim to counter the left banking tendency, like IRL?

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4

None of these variables are really good for what you want. P Factor is something different then torque forces. And the other two have more to do with general inertia, meaning with fast force changes.
The torque on roll comes from mainly two variables -

“torque_on_roll” - what a surprise^^,
and with the modern prop model enabled also
“prop_mod_moment_scalar_roll” from the engines.cfg

Setting the latter to 0 - should disable any torque on roll you experience.

But the left banking shouldn´t be that high in the TBM850. Do you have the latest Version of the TBM? Or do you have only a slight roll to the left and it just bothers you (which is ok, btw.) Just want to be sure, you are not having bugs.

Kind Regards

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5

torque_on_roll is already adjusted but appears to control the effect on ground only, not in the air. prop_mod_moment_scalar_roll in engines.cfg I will try.

With my fresh installation the aircraft, once airborne without any right aileron input banks left beyond 45° after few seconds. I have no real world experience with turboprpops but for me and my controller setup the effect appears too strong, which is why I am looking for a reduction (…and it relates more to general aircraft twitchiness in MSFS, rather than the Black Square add-on specifically).

Aileron trim as suggested by @PZL104 is a real option of course, however requires adjustment inflight, because upon landing without torque the aircraft would bank right.

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If there is a roll factor, then it rolls and rolls without any input. The question is, how hard do you have to counter steer to avoid rolling? Really Hard or just a little? And are you level flying already or still in climb? In Climb the p-factor indeed would play a roll in the roll.

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Nope, that’s for rhe rolling moment (in flight)

Rudder trim, not aileron trim

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Counter steering is moderate and in climb. P-factor in climb vs. level has not yet been considered, will pay attention upon next test.

Thanks for your input!

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The aircraft is rolling (banking) left, so I need to apply right aileron.

Any way, I will re-test the flight_model.cfg settings because I made adjustments in-sim, where settings are not always changed upon reloading aircraft.

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@sgaviation Nope. Just try rudder trim…as IRL.
The reasons for the left banking tendency are more complex than you assume :wink:

Aileron trim is usually used if you are e.g. experiencing a fuel imbalance.

If you try to correct the left turning/rolling tendency with aileron trim, the slip indicator would be off center, at least IRL.

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11

Use the quick reload button on the Behaviours window.

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I abandoned the Quick Reload option because it did not reliably reload aircraft textures upon repainting. However it appears that it reloads the config. Will give it another try.

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So, here’re my findings after various tests:

In flight_model.cfg the items torque_on_roll and engine_wash_on_roll influence the turning tendencies during takeoff roll only.

Once airborne, the engine.cfg items prop_mod_moment_scalar_pitch, prop_mod_moment_scalar_yaw & prop_mod_moment_scalar_roll control the engine/propeller effects in the air.

This applies to the Black Square TBM 850. As mentioned above certain settings in the flight_model.cfg may be disabled for some aircraft.

Next I will work with the trim settings as suggested.

Thanks for the guidance! :muscle:

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14

Nice find!

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That’s correct. Resync will sync the config files and most everything to do with a plane except the livery. Asobo removed the ability to resync the livery a year or two back because of “lack of interest” or some such.