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STF-DIR

MSFS B737-800NG Flightmodel in Turns

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Hello,

 

i have a Question to a Flightmodel in MSFS.
It flies more or less ok, but the Problem is in making a Turn.

Lets say we fly stable at 8000ft at 220kt, no wind.
When i now do a 90 deg turn left or right, the nose dives sooo much down and i need sooo much trim / elevator forces to hold the Altitude.
I am a PPL Pilot and know a little bit about Flightdynamics, not of a B737, but on a cessna. I know it is not to compare, but i know that
also a B737 should not need soooo much trim/elevator and also thrust to holt the Altitude in a turn like described above.

So my question is if anyone can help here and give me maybe a idea which parameter in the flightmodel.cfg is to change to make this behavior a bit better?

 

Thanks a lot
Matthias


I78700K at 4.2, 16GB Ram,1080Ti,P3Dv4.4

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.........and that is perfectly normal for a 737.  This flight model was tuned and re-tuned by real airline pilots from United Airlines and such that fly the type.  I would not tinker with the flight model just to make it feel like you think it should behave.  Any other developer, I would question it; PMDG......I would leave it alone!!!


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9 minutes ago, DMullert said:

.........and that is perfectly normal for a 737.  This flight model was tuned and re-tuned by real airline pilots from United Airlines and such that fly the type.  I would not tinker with the flight model just to make it feel like you think it should behave.  Any other developer, I would question it; PMDG......I would leave it alone!!!

Since PMDG hasn't released a 737-800 in MSFS just yet, I'm going to presume that the OP is referring to the default airplane, not the PMDG add-on.

And no, the nose does not drop dramatically on a 737 in a turn, assuming of course, that the bank angle is not excessive (e.g. below 30 deg).  And any thrust change required to maintain airspeed in the turn should be very minor.

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47 minutes ago, STF-DIR said:

Hello,

 

i have a Question to a Flightmodel in MSFS.
It flies more or less ok, but the Problem is in making a Turn.

Lets say we fly stable at 8000ft at 220kt, no wind.
When i now do a 90 deg turn left or right, the nose dives sooo much down and i need sooo much trim / elevator forces to hold the Altitude.
I am a PPL Pilot and know a little bit about Flightdynamics, not of a B737, but on a cessna. I know it is not to compare, but i know that
also a B737 should not need soooo much trim/elevator and also thrust to holt the Altitude in a turn like described above.

So my question is if anyone can help here and give me maybe a idea which parameter in the flightmodel.cfg is to change to make this behavior a bit better?

 

Thanks a lot
Matthias

There are no difference in terms of flying physics between 172 and 737. Of course bigger airplane has more inertia and controls not as sensitive as in 172. Bigger airplanes also have lag spooling response between throttle vs engine response.  I'm using TM airbus stick and to me

737 turns exactly the same as in GA aircraft. May be you have some kind of controls problem like runway elevator trim or something? 

P.S. Here is pilot comparison between B737 and A320.

"The main difference between the two, as touched on earlier, is the flight control “law” system utilized in the “bus.” In a typical aircraft, if you want to turn left 25 degrees, you turn the control column to the left and apply a slight back pressure to maintain altitude and hold some measure of input to maintain the turn. Not so on the Airbus. Instead, you move the sidestick to the left, with no need to apply backstick until above 30 degrees. Upon reaching 25 degrees angle of bank, you can release the stick and the flight control system will maintain the “requested” angle of bank and pitch attitude."

https://skiesmag.com/news/airbus-versus-boeing-a-pilots-perspective/


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48 minutes ago, Bob Scott said:

Since PMDG hasn't released a 737-800 in MSFS just yet, I'm going to presume that the OP is referring to the default airplane, not the PMDG add-on.

And no, the nose does not drop dramatically on a 737 in a turn, assuming of course, that the bank angle is not excessive (e.g. below 30 deg).  And any thrust change required to maintain airspeed in the turn should be very minor.

There is no default 737-800 in MSFS. Only A320 Neo, 747 and 787 (DLC)

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Is the OP thinking of the Bredok3d 737 perhaps? I can't vouch for that aircraft as I don't have it, but the PMDG 737's all have appropriately modelled handling characteristics, including the subtle differences between the -600, -700 and -800. 

If you roll into a turn in a swept wing jet and don't apply the requisite back pressure, you are going to lose altitude. The subjective impression of how much back pressure is required will be at least partly influenced by what hardware you are using and the axis sensitivity settings you have in-sim.

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Mark Adeane - NZWN
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When you say you're doing a 90 degree turn, do you mean you're turning from 180 to 270, or are you banking 90 degrees?

Because if you're doing a 90 degree (banking) turn, I don't think any 737 has the rudder authority to keep the nose from going straight down. I'd be surprised if the DC-10/MD-11 weren't the only transport category aircraft that had that much rudder authority.

If you're talking about a standard rate turn, then with the 737 you have to trim up, or back pressure on the yoke to maintain level flight. This is true for all aircraft; FBW aircraft do it for you.


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20 minutes ago, WestAir said:

When you say you're doing a 90 degree turn, do you mean you're turning from 180 to 270, or are you banking 90 degrees?

 

I think he meant 90 degrees heading offset. Since 60 degrees bank would caused load fact of 2G and 90 degrees load factor 6G!

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1 hour ago, markadeane said:

including the subtle differences between the -600, -700 and -800. 

there is not at the moment a 738 available for MFS from PMDG…

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Hello and thanks for all the Answer.

I should first make some things clear:

Assume i fly at 8000ft at 220 kt stable and a good trimmed Aircraft. Tanks around 4000kg and around 14to Payload. 
Then yes, i mean a TURN of 90 degrees and for sure not a Bank of 90 degrees. I wrote i am just a private Pilot, but a Pilot. So i mean i know that a B737 have a bank of max 30 degrees for such a Turn:-)

Yes, when i turn i have to add A BIT of back pressure at the Elevators and also maybe A BIT of Thrust to hold the Altitude, but i think it is not that i have to trim from 5 to more then 10, like the AP is doing.
 

Just to make that a bit more clear.

But the Question is still if there is any parameter in the flightmodel.cfg that i can change to minimize this effect a bit ?
It would be really nice to know what parameter of the flightmodel.cfg i can start to change and see what happens.

Thanks
Matthias


I78700K at 4.2, 16GB Ram,1080Ti,P3Dv4.4

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Posted (edited)

Maybe try the PMDG.

Edited by flyingpauls

Paul Schmidt

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33 minutes ago, STF-DIR said:

Hello and thanks for all the Answer.

I should first make some things clear:

Assume i fly at 8000ft at 220 kt stable and a good trimmed Aircraft. Tanks around 4000kg and around 14to Payload. 
Then yes, i mean a TURN of 90 degrees and for sure not a Bank of 90 degrees. I wrote i am just a private Pilot, but a Pilot. So i mean i know that a B737 have a bank of max 30 degrees for such a Turn:-)

Yes, when i turn i have to add A BIT of back pressure at the Elevators and also maybe A BIT of Thrust to hold the Altitude, but i think it is not that i have to trim from 5 to more then 10, like the AP is doing.
 

Just to make that a bit more clear.

But the Question is still if there is any parameter in the flightmodel.cfg that i can change to minimize this effect a bit ?
It would be really nice to know what parameter of the flightmodel.cfg i can start to change and see what happens.

Thanks
Matthias

Can we just clarify Matthias, are you talking about the Bredok B737 max, as there is no B737-800 in MSFS yet. 


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no, its the 737-800 from Prosim737

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I78700K at 4.2, 16GB Ram,1080Ti,P3Dv4.4

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Yes, it is a special airplane only for Homecockpit builders, but you can check it out:

Download the latest version here:
https://cdndl.prosim-ar.com/ProSimB738/Beta/?C=M;O=D

You have then just to unrar it to any directory.
Then you need to start the Prosim737 Suite Server and you need to start a instance of Prosim Display and Prosim FMC.
After starting Prosim Server you can download the evalution version of the Model AND THE MODULE for FS2020 from the Menu via Help->Updates->Register Add Ons.
The Flightmodel has the version 1.09 and the Module is version 1.0

Then you have a 30 min Evalution Version, which is enough to Test.
Just run Prosim Server, Prosim Display and FMC. Enter all the Numbers and then you can control the AP via Prosim Display.
So via Slew Control you can put tha airplane in 10000ft and at 8000 it is hopefully stabilized.
Then FD, AT and AP on and then change just the HDG to 90 deg. right or left and you will see in the PFD the amount of Pitch and in the upper EICAS the
amount of Thrust the AP adds to hold the Altitude. Also the Trim goes very very high.

Matthias

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