• Which the release of FS2020 we see an explosition of activity on the forun and of course we are very happy to see this. But having all questions about FS2020 in one forum becomes a bit messy. So therefore we would like to ask you all to use the following guidelines when posting your questions:

    • Tag FS2020 specific questions with the MSFS2020 tag.
    • Questions about making 3D assets can be posted in the 3D asset design forum. Either post them in the subforum of the modelling tool you use or in the general forum if they are general.
    • Questions about aircraft design can be posted in the Aircraft design forum
    • Questions about airport design can be posted in the FS2020 airport design forum. Once airport development tools have been updated for FS2020 you can post tool speciifc questions in the subforums of those tools as well of course.
    • Questions about terrain design can be posted in the FS2020 terrain design forum.
    • Questions about SimConnect can be posted in the SimConnect forum.

    Any other question that is not specific to an aspect of development or tool can be posted in the General chat forum.

    By following these guidelines we make sure that the forums remain easy to read for everybody and also that the right people can find your post to answer it.

Turboprop Engine power

VSP4264

VSP4264

Messages
171
Country
brazil
Hi!

Im tunning some FDE on turboprop aircrafts and have a serious doubt...

[TurbineEngineData]
fuel_flow_gain = 0.0225
inlet_area = 0.5
rated_N2_rpm = 37500 // 33000
static_thrust = 85

[turboprop_engine]
power_scalar = 1
maximum_torque = 1865

The static thrust is in LBS... but engine factory data is in SHP... like PW PT6 of C208EX is 867SHP... what the way to convert 867SHP to XXX LBS? PW118 is 1800SHP... how many LBS is same value of 1800SHP power?
 
Turboprop thrust is really unimportant and small. What drives the thing is prop thrust. That comes from shaft horsepower, torque and propeller efficiency and there is not a direct relationship between thrust and SHP. So you cannot simply convert between them.
Roy
 
horsepower-torque-conversion-formula.jpg

I think may be the formula you want?
There is an on-line converter HERE
Is that what you wanted, Mr. VSP?

If it's not, then I apologize for misunderstanding.
Pat☺
 
Pat,
That is the relationship between HP and torque. What governs the prop thrust in pounds is propeller efficiency. You can have great torque but if your prop efficiency is low, you will have low thrust, simple as that. Efficiency varies with airspeed and pitch, it is a complicated process.
That is what I meant by saying there is no direct, fixed relationship between pounds thrust and SHP.
Roy
 
Ahh, I apologize. I misunderstood. I thought that was what the OP was looking for.
You're absolutely correct, of course. Sorry for the misunderstanding. :ziplip:

As the saying goes, My Bad :laughing:

Have fun!
Pat☺
 
My intention is for the Carenado C208EX to actually have 867SHP power, but I do not know how to determine this in LBS over there in the power field of the aircraft.cfg
 
Mathematically, horsepower equals torque multiplied by rpm. H = T x rpm/5252, where H is horsepower, T is pound-feet, rpm is how fast the engine is spinning, and 5252 is a constant that makes the units jibe.
Click to expand...

So for you it's maximum torque times maximum prop RPM divided by 5252. Since you know the horsepower it would be horsepower divided by (maximum prop RPM divided by 5252).
 
VSP4264 said:
Im tunning some FDE on turboprop aircrafts and have a serious doubt...

[TurbineEngineData]
static_thrust = 85

The static thrust is in LBS... but engine factory data is in SHP... like PW PT6 of C208EX is 867SHP... what the way to convert 867SHP to XXX LBS? PW118 is 1800SHP... how many LBS is same value of 1800SHP power?
Click to expand...
Static thrust is the residual thrust from the exhaust stacks. Btw, simply using RW values like 867SHP doesn't make much sense since you don't know how the FDE designer built the FDE.
You can easily design an airplane with spot on RW performance and totally 'wrong' numbers in the air and cfg file.

Btw, the entry in general section of the cfg file says -114A but the actual entry in the cfg file states -140 and the performance of the EX matches the performance data with the -140 engine.
 
Last edited:
Bstolle,

You is a genious that make the magic patch for Carenado C208B? You work on C208EX too? Or simply apply your patch on C208EX solve the trouble?
 
The thrust you are talking about is Residue Thrust from the turbine section and it is pretty much useless in a turboprop. 85lbs of thrust is nothing, won't even sustain low speed taxi.

There is no direct relationship between engine performance and propeller thrust.
 
If the exhaust stubs point back there’s even an exhaust thrust from a big piston engine, but it’s fairly piffling.
 
If correctly designed, the exhaust shape/thrust can noticable increase the performance. When Pilatus changed the design of the exhaust ducts on the PC-7 the cruising speed increased by more than 10kts.
 
Fokker 50 flying little slow than ATR42-300 because exhaust ducts design, and 42-300 coming with PW121 (2.100 Shp) meanwhile F50 coming with PW125 (2500 Shp) for example how "thrust" of gases help on performance.
 
pinkjr said:
So more to my point. My toy turbine engines almost put out that much.
Click to expand...
How would you know, since you definitely don't get 85lbs thrust when taxiing at low power? FYI, most jets (with a similar thrust/weight ratio) taxi at idle thrust.
 
Last edited:
bstolle said:
How would you know, since you definitely don't get 85lbs thrust when taxiing at low power? FYI, most jets (with a similar thrust/weight ratio) taxi at idle thrust.
Click to expand...

You are comparing jets to turboprops, which is a big no-no. And by the way, NO, not all jets taxi at idle, most large bypass turbofans do.
A turboprop, in comparison, has almost negligible torque at idle, and any net thrust you see at idle is generated by the prop, and NOT the turbine core.
 
Suggest you try to read again and/or understand what I wrote before replying. Over and out.
 
You must log in or register to reply here.
Back
Top