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Lenny777

Recommendations for best GA twin turbo prop or Piston

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2 hours ago, NorwegianAviator said:

But as far as I know and according to several developers, this requires them to alter the thrust curves for the jet engine so that it produces more thrust at idle and very low power settings than it's supposed to (PMDG does this in the NG, not sure about their 777 and 747). In my opinion, this is not a very good solution, but just a tweak to get around the core issue and makes operation on the ground more unrealistic, because the thrust curves are not going to be correct.

But back to turboprops which this thread is all about. Do you have a solution to fix the turboprops in P3D?

The biggest problem with turbo props is that the start up routine is fairly fixed and is extremely sensitive to prop over-rpm if you set the power and prop response to reasonably quick. If it wasn't for that fixed start up routine, which is hard coded (or at least was in FSX) then there would be much more leeway to tweak other settings. Some developers sort of cheat by eliminating prop reaction sounds (default Caravan in FSX) but if you look at the gauges you'll see prop overspeed events.

If the start up routine could be bypassed, then the rest of the T-prop modelling is not bad at all, and several xthousand-hour turbo-prop pilots who've tested for me in the past confirm that things are not nearly as "broken" as some claim.

Most complaints seem to be about the start up routine and that response to power changes is too slow. It is a little slow solely because speeding up normal power response tends to make the start up run away. You can speed up normal engine operations a lot, but that makes the start-up grossly over-rev. It's a shame because many of the FDE routines in FSX/P3d are actually quite well done, with the advantage that parameter functions work very smoothly between points set in the tables, something custom exterior flight modelling doesn't achieve so well unless it is done with infinite care.

Edited by robert young

Robert Young - retired full time developer - see my Nexus Mod Page and my GitHub Mod page

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2 hours ago, FDEdev said:

I don't understand what's so unrealistic with the increased idle thrust on ground besides the slightly higher fuel flow, and I severely doubt that you would notice the incorrect thrust curves during operation.

Since we have different opinions about what needs to be 'fixed' I doubt that I would have a solution that's acceptable to you since I e.g. usually design my turboprops so that they taxi at idle power without actually simulating beta. That said, beta only indicates the range where the power lever controls the propeller blade angle, nothing else.

  

This shouldn't be neccessary if LM fixed the ground friction and improved the engine simulation (which has stayed untouched since FSX and probably even before that). Flying a 737, instead of using 200 kg of taxi fuel you end up using close to 400 kg due to this issue with ground friction requiring a modified thrust curve. Probably not a big deal for most simmers, but for more hardcore simmers and simmers who also fly in real life, it's a much bigger deal in my opinion. It's not supposed to work this way that's my point. After all, it's a 200USD professional sim as LM claims and not a game for entertainment purposes.

The whole point in having beta range is to be able to control taxi speed in a controlled manner, with minimal use of brakes. If you start taxing eg. a Dash 8-100 with the power levers in flight idle, the brakes would probably catch fire before you reach the runway, because it would require you to hold the brakes continuously during taxi to avoid speed runaway. In a jet, I agree that you would probably not notice the incorrect thrust curves during flight, but on the ground you certainly would if you have RL experience on the type.

That being said, I'm still open for suggestions on how to fix my turboprops in P3D 🙂


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45 minutes ago, NorwegianAviator said:

In a jet, I agree that you would probably not notice the incorrect thrust curves during flight, but on the ground you certainly would if you have RL experience on the type.

This doesn't make sense. Since the N1/N2 is identical to the RW value and engine response is identical as well, how would you notice a difference (except for the FF).

I don't know any pilot who knows the exact idle thrust value for 'his' airplane. Furthermore if thrust values are given they are usually for the uninstalled engine.  

@robert young  That's one of the reasons why I prefer P3D so much. No more startup problems without seriously compromising the spool rate 🙂 

 

 

Edited by FDEdev

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1 hour ago, NorwegianAviator said:

This shouldn't be neccessary if LM fixed the ground friction and improved the engine simulation (which has stayed untouched since FSX and probably even before that). Flying a 737, instead of using 200 kg of taxi fuel you end up using close to 400 kg due to this issue with ground friction requiring a modified thrust curve. Probably not a big deal for most simmers, but for more hardcore simmers and simmers who also fly in real life, it's a much bigger deal in my opinion. It's not supposed to work this way that's my point. After all, it's a 200USD professional sim as LM claims and not a game for entertainment purposes.

The whole point in having beta range is to be able to control taxi speed in a controlled manner, with minimal use of brakes. If you start taxing eg. a Dash 8-100 with the power levers in flight idle, the brakes would probably catch fire before you reach the runway, because it would require you to hold the brakes continuously during taxi to avoid speed runaway. In a jet, I agree that you would probably not notice the incorrect thrust curves during flight, but on the ground you certainly would if you have RL experience on the type.

That being said, I'm still open for suggestions on how to fix my turboprops in P3D 🙂

Not wishing to blow my own trumpet, but the RealAir Duke Turbine does have an effective beta range for exactly what you describe. If you assign a graduated "reverse" and also keep the condition lever near low, you can get quite good control of the beta range sufficient to gently slow you down or go full reverse when taxiing or after landing. As far as I know there are other addon aircraft which can achieve the same thing. In the Duke you can pull the levers back (set to pull both by right mouse button hold and drag) or you can assign a lever or keys to the same thing. When taxiing you can select almost low idle condition lever then play with the power levers for a little forward movement then bring back the levers for a small beta value and it acts as a gentle or not so gentle brake, depending on how harsh you are with the levers.

The higher you set the condition lever, the more the effective power can run away and over accelerate while taxiing. The advised setting is low condition lever position then a tad of forward or idle power (depending on aircraft weight) to get moving then ride the beta range with subtle movements to contain the acceleration.

Are you sure you are not exaggerating the problem here? A few years ago I sat in P2's seat and watched a King Air pilot do exactly the above and it was quite close to what is possible in FSX and P3d.

You can tweak the settings in any default or other Turbo-prop in both FSX and P3d. All of it is done in the aircraft cfg file engine and prop sections. There aren't many parameters to play with and you need to spend time investigating the interaction between prop radius, beta range, power, rpm, prop inertia and other params. It can be done but it does require a lot of patience and experimentation, and some experience.

Edited by robert young

Robert Young - retired full time developer - see my Nexus Mod Page and my GitHub Mod page

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5 minutes ago, robert young said:

Not wishing to blow my own trumpet, but the RealAir Duke Turbine does have an effective beta range. If you assign a graduated "reverse" and also keep the condition lever near low, you can get quite good control of the beta range sufficient to gently slow you down or go full reverse when taxiing or after landing. 

The problem with most users is that they complain about the lack of realism because you get a tiny increase in fuel flow and RPM if you go below the FSX idle setting.

IMO, if you aren't using a Dash8 throttle quadrant replica for your simming experience, the whole discussion is quite useless since the equipment you are using isn't 'realistic' either. 

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I think you can tweak it by altering this:

 

[GeneralEngineData]
min_throttle_limit =xxxx

As you probably know on jets it sets the max reverse thrust power and it does a similar thing with Turbo Props. While the theoretical values might be off, in practical terms it works.

Edited by robert young

Robert Young - retired full time developer - see my Nexus Mod Page and my GitHub Mod page

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Doesn't work. The problem is that even 1% above/below 0% throttle increase fuel flow and hence triggers complaints from a few hard core simmers.

IMO turboprop tuning requires the same amount of work in the air and the cfg file.

Edited by FDEdev

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1 hour ago, NorwegianAviator said:

That being said, I'm still open for suggestions on how to fix my turboprops in P3D 🙂

I'm afraid up to the level you seem to expect, it is not possible at all without custom coding many parameters. 

Tuning FDE/Air file is not enough for accurate ITT, Oil Press/Temp, Beta behavior (without FF increase), correct FF, etc.

Even though startup sequence is improved in P3D, it is not possible to simulate different scenarios (hot start, hung start,in flight start, etc) with accurate realism.

Fair to say most users don't care about such level of details, and I assume they are very happy with what they can get from popular turboprop addons currently available.

 

Tom

 

 

 

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37 minutes ago, FDEdev said:

The problem with most users is that they complain about the lack of realism because you get a tiny increase in fuel flow and RPM if you go below the FSX idle setting.

IMO, if you aren't using a Dash8 throttle quadrant replica for your simming experience, the whole discussion is quite useless since the equipment you are using isn't 'realistic' either. 

This can be a "simulation of a simulation" with about any throttle using FSUIPC axes calibration. The Thrustmaster HOTAS, for example, has markings, when used in conjuction with FSUIPC, can have a "beta range". Again, not perfect, but enough to "simulate" the operation of a King Air in taxi. 

Agreed, the fuel flow, etc are a little wonky compared to real world.

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1 hour ago, FDEdev said:

This doesn't make sense. Since the N1/N2 is identical to the RW value and engine response is identical as well, how would you notice a difference (except for the FF).

I don't know any pilot who knows the exact idle thrust value for 'his' airplane. Furthermore if thrust values are given they are usually for the uninstalled engine.  

@robert young  That's one of the reasons why I prefer P3D so much. No more startup problems without seriously compromising the spool rate 🙂 

 

 

I'm not a developer, but you would need a higher thrust setting to get the plane moving and to keep it moving because of the wrong ground friction, wouldn't you? Fuel flow would be off by several hundreds of kilos, especially with a long taxi.


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MSFS | DCS | X-plane 12

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1 hour ago, FDEdev said:

The problem with most users is that they complain about the lack of realism because you get a tiny increase in fuel flow and RPM if you go below the FSX idle setting.

IMO, if you aren't using a Dash8 throttle quadrant replica for your simming experience, the whole discussion is quite useless since the equipment you are using isn't 'realistic' either. 

That's basically because it's not being simulated correctly in the sim, and we become dependent on different "tweaks" to make it work. 
I'm not using a dhc8 throttle quadrant replica, but you can set this up using fsuipc. The Majestic Q400 does this great by default, but they're using external simulation for everything as far as I know.


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MSFS | DCS | X-plane 12

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45 minutes ago, taguilo said:

I'm afraid up to the level you seem to expect, it is not possible at all without custom coding many parameters. 

Tom

 

 

 

I'm afraid so also 😄
We can only hope that this will at some point be fixed.

 

47 minutes ago, taguilo said:

Fair to say most users don't care about such level of details, and I assume they are very happy with what they can get from popular turboprop addons currently available.

 

Tom

 

 

 

I think that's because most simmers don't fly in real life, so they have no knowledge about it.


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MSFS | DCS | X-plane 12

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10 minutes ago, NorwegianAviator said:

I'm not a developer, but you would need a higher thrust setting to get the plane moving and to keep it moving because of the wrong ground friction, wouldn't you? 

Again, no. N1/N2 are identical compared to real world values. 

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2 minutes ago, NorwegianAviator said:

I think that's because most simmers don't fly in real life, so they have no knowledge about it.

That's a pretty arrogant and wrong assumption.  So you don't fly jets in any sim because you don't fly jets IRL either. Is this correct?

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1 minute ago, FDEdev said:

Again, no. N1/N2 are identical compared to real world values. 

I understand that, but due to the wrong ground friction you will need to add a bit of power to get the plane rolling, and also to keep it rolling. It will not keep moving a idle power.


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MSFS | DCS | X-plane 12

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