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Bdub22

TRQ readings in TBM

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Hi all,

So I've been using the TBM mod and love it. I had a question about the torque and power though. I can't use 100% power without the TRQ going into the red. I know you don't need to full power to get this girl into the air, but even at higher elevations, it'll still go into the red. Is this just normal ops or am I doing something wrong?

As always, thank you. 

Cheers

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I always throttle back a bit after takeoff to stay under the red line.. not sure if the real airplane can happily fly with the throttle to the wall..


Bert

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Posted (edited)

That's how it really is in a turbine, unless it has FADEC, most turbo-props don't, but that's another story for another time.

So, long story short, Yes, you can over torque or or over temp a turbine prop engine and destroy it very quickly. 

Quite often one will either hit max torque first or max temp first depending on the ambient conditions eg, hot day or high alt' runway.  that's why real world pilots don't get to fly them generally until they have quite a few flying hours and more experience under their belt.

The point is with turbine engines is that they develop a tremendous amount of power for their size and weight and are great for "above the weather" operations, high speed/high performance (climb/terrain etc) and for the most part, much more reliable then piston engines.

The down side is, they're expensive to maintain, they run very hot, particularly in the (hot ) section of the turbine engine with the metal turbines in the power section of the engine running very close to their melting point, hence the red line limits which must be strictly adhered to or you would end up with a very short career in aviation.

 

Therefore, basically, Stay under the red line of either limit or you'll cook it.

Also, torque will decrease with altitude, so you can increase torque in the climb, BUT! only until you reach either limit!!

Edited by toucanair
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I noticed an issue last night actually.  Applying about half throttle and my ITT was spiking into red...seems a little off.


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13 hours ago, Bdub22 said:

So I've been using the TBM mod and love it. I had a question about the torque and power though. I can't use 100% power without the TRQ going into the red.

I'm guessing you're using the " tbm930-improvement" mod v.0.5.11?  This was indeed a good mod (and still is in many ways) but the recent ASOBO update that addressed many turbine deficiencies actually made the turbine dynamics much more realistic than the mod.  However, myself and others also missed some of the other mod adjustments, so some of us have made a "hybrid" version to really enjoy this aircraft:

  • Overwritten the mod's flight_model.cfg with the new default
  • Edited a few items to recover mod's doors, steering, and gear drag

Voila! a Huge improvement in more realistic turbine performance while maintaining some of the mod's other attributes.  I've found that I can max the throttle on takeoff without over-torquing.  A little after lift-off I must reduce a little to protect against red-lining.  As I continue to climb I have to add power to stay in the upper 90's (pretty realistic) and reduce power in a descent (also realistic).

The WT g3000 mod is still important.  I also use the WT recommendation that removes the current backup ASI indicator's issue with indicating an improper over-speed condition.


Randall Rocke

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45 minutes ago, RandallR said:

The WT g3000 mod is still important.  I also use the WT recommendation that removes the current backup ASI indicator's issue with indicating an improper over-speed condition.

Where can I find that recommendation for the over-speed condition on backup ?. Had a look around the readme files - maybe i missed it. Thanks


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In the WT g3000 Read.me under ### Known Issues :

- \[Misc\] TBM 930: the standby airspeed indicator still redlines at lower speeds than it should. If this bothers you, change the `crossover_speed` setting in `asobo-aircraft-tbm930\SimObjects\Airplanes\Asobo_TBM930\flight_model.cfg` to 0. If you use the TBM improvement mod, you should change the value in the `flight_model.cfg` file found in that mod's folder.

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Randall Rocke

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10 hours ago, ryanbatcund said:

I noticed an issue last night actually.  Applying about half throttle and my ITT was spiking into red...seems a little off.

Thanks. I’ll stick with FSX for now as nothing has changed. 

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15 hours ago, RandallR said:
  • Edited a few items to recover mod's doors, steering, and gear drag

Could you give details about these items and their values ?

Thanks

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I can't recall who originally posted these but they all work:

=====================================================

I just replaced the "flight_model.cfg" and "engines.cfg" from the mod with the new ones from the TBM folder to take advantage of the changes. After that I only added the modified values to increase the drag of the gear, increase the deflection of the nose gear and remove the 30% throttle gap.

There is only one pitfall: When replacing the "flight_model.cfg" make sure to copy the [INTERACTIVE POINTS] section from the old file to the new one. Otherwise the doors won't open anymore.

===============================
Interactive points:
===============================

[INTERACTIVE POINTS]
number_of_interactive_points=3
interactive_point.0=0.3, -14.4, -2.2, 0, 0, 25, 0, -90, 0, 0, 0, 0, 0, 0
interactive_point.1=0.3, -22, -2.1, 0, 0, 25, 0, -90, 0, 0, 0, 0, 0, 0
interactive_point.2=0.3, -11.2, -2.2, 0, 1, 25, 0, -90, 0, 0, 0, 0, 0, 0

===============================
Nose Wheel?:  In the original file you'll see:
===============================

max_castering_angle = 3.14159265358979 ; Defines the maximum angle a free castering wheel can take (in radians).
point.0 = 1, -7.5, 0, -4.14, 720, 0, 0.52, 15, 0.327, 1.5, 0.9, 13, 13, 0, 0, 0, 4

Change the 15 to 60 so it looks like the below:

max_castering_angle = 3.14159265358979 ; Defines the maximum angle a free castering wheel can take (in radians).
point.0 = 1, -7.5, 0, -4.14, 720, 0, 0.52, 60, 0.327, 1.5, 0.9, 13, 13, 0, 0, 0, 4

(Note: I use 50 for this, as I found the steering response too sensitive during takeoff.  Now takeoff is more controllable and I can still easily do a U-turn on a small strip)

===============================
Drag Coef on Gear
===============================
In flight_model.cfg look for: drag_coef_gear = 0.01000

Change it to be: drag_coef_gear = 0.04700 

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Randall Rocke

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One other item for adjustment.  You may have noticed that the author of the recommended adjustments also stated: "and remove the 30% throttle gap."

I don't think they posted where they adjusted this, and I've noticed that although the turboprop adjustments have been excellent, the throttle response at the beginning of application was way slow.  I did a little searching in the engine.cfg today and found the following:

=====================================
[TURBOPROP_ENGINE]

tp_high_idle_throttle_pos = 30
=====================================

I reset this to "0" and the throttle response is good.

 

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Randall Rocke

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Guys, you need to do some reading on turboprop operation.

As in most, the TBM has a derated engine - the Pt6A-66D can produce 1825 shaft horsepower at sea level on a standard day. The gearbox (between the power section and the prop) is designed to take up to 850shp maximum. Even at an airport with a really high elevation, you will never use 'full throttle' on takeoff. 

As you climb, torque decreases as the air density decreases and you may then add more 'throttle' to maintain max Trq. There will be a point where you should reach maximum temperature, and no further power increase should be possible.

 


James W

 

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Yes - this is very close to how the TBM is running right now.  In fact, it's almost spot-on.

The only thing that varies from this a little is I've noticed that I can firewall the throttle under the new settings on takeoff and not over-torque for a couple of thousand feet.  But I can't leave it there as it will go over 100%.  Therefore, I usually set about 95% on takeoff, then keep increasing torque as I climb - this is necessary to maintain max torque.  When descending, the opposite is true - I need to decrease torque as the air density increases.


Randall Rocke

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