as I read Asobo will work on the turboprop engine logic I just thought “hey, great! Finally!” but there might be one thing left behind: free turbines.
Some might not know about these engines but they are used on big turboprops like the Dash 8 Q400 - in short terms the engine is not connected directly to the turbine, instead the engines exhaust drives a third turbine stage which drives the prop. The benefit of this is that the prop RPM is Independent from the engines N2 RPM so the crew can just use a more silent low RPM setting on approaches and still keep enough engine power if a go around is needed.
On the Dash 8 Q400 for example we got two sets of levers - one is for the turbines power, the other for prop speed settings (feather to 850 to 1020). I’d really like to properly simulate that using the engine.cfg but that’s not possible right now as there is “just” a gear box which simulates the prop beeing connected to the turbine.
It would be nice to have something like this:
isFreeTurbine=true
propspeedMin=850; Min prop speed in RPM
propspeedMax=1020; Max prop speed in RPM
Also this - to work entirely correct - would need some additional buttonmapping for the prop speed selector (which is different from prop pitch!)
Anyway I think it would be really some great addition
MSFS, like FSX/P3D, does simulate free turbine turboprops.
(If you start any turboprop in MSFS engine RPM increases long before prop RPM does)
The problems in FSX/P3D used to be (and probably are in MSFS as well) fixed turbine turboprops.
I don’t understand the buttonmapping request for prop speed?
You are adjusting prop speed with the condition/RPM levers and (except in beta range) you can’t directly control prop pitch.
If you want buttons to select a specific prop RPM, that’s an easy one for FDM/gauge developers.
This logic not only happen on the DASH 8
Every today turboprop engine have a free turbine.
You cannot set a max 1020RPM for every turboprop.
I work in the business aviation, this I know B300, B90, TBM.
Pilots drive their engine with Torque and RPM.
They don’t even look at the N2.
Example on B300, most of time of your flight you set a fix RPM around 1500tr/min (set with propeller pitch lever) and and then adjust the torque only. (With power lever)
Around 80 Newton.meter
It is quite strange to explain, but this is how they fly this aircraft. (
If you want to go in details,
Power levers set the fuel flow but also impact the torque and prop speed as well.
All work together hydro mechanically through the FCU.
No FADEC/EEC on this aircraft
Don’t know which manual you are referring to, but the POH, AFM all state propeller lever.
Never called, or hear someone call them propeller pitch levers.
The power levers don’t affect prop RPM (within the governing range)
80Nm? Seriously?
Don’t know what FADEC/EEC has to do with the propeller levers.
On the latest aircraft like the TBM, PC12, or ATR.
You won’t find propeller lever anymore, only the power lever, and fuel cut off.
Everything is managed by the EEC
The ATR (including the newer -600) still has prop / conditions levers, although mostly in AUTO during flight you could still adjust to 100% / OVRD if needed. Propeller is controlled by the PEC on the ATR, not EEC.
I assume Asobo will be working on the free-turbine engine model if they say they are gonna work on turboprops considering all three turboprops in MSFS are free-turbines (PT-6).
Little nit-picking maybe but both the compressor section and the power section are connected to a turbine, the two turbines themselves are not interconnected (three turbines, one power spool and two compressor spools if you are talking about PW100).
I’m not sure this is a benefit of a free turbine engine, rather a benefit of modern electronics like FADEC / PEC / EEC. A free turbine does not spool up automatically to higher RPM, it is still a constant speed propeller so unless you tell the PVM to spool up, it will maintain constant speed (low RPM) which is insufficient for go-around. The Kingair is also a free turbine for example, still you need to set high RPM on approach due to the absence of an EEC or equivalent.
What do you mean with prop speed selector? Propeller levers are not working any differently on conventional turboprops (e.g. Kingair or Caravan) compared to a piston, modern turboprops have either a condition lever with an auto mode or a power management selector, or completely single lever design.
I just meant the simulation end, right now you can control prop pitch but you cannot set a desire prop speed. I know irl this might be automatic in most modern aircraft but as I’m working on a DH8D for the sim it would be handy (esp. as it does not feature a cockpit right now)
Also I did not find any way by now to limit the prop speed by now, just N2 torque - using real life values, esp. on the gear box ratio, results in 1800 RPM on the prop which is way too fast generating too much output. adjusting the ration on the other end results in too low prop speeds (500 RPM while idle).
So if they are working on turboprop logic they should not just focus on prop effectiveness on high altitudes (which is the other thing) but also on the parameters one can define. It’s simply not complex enough by now
On no aircraft do you directly control prop pitch, you set the propeller RPM with the prop lever and the constant speed unit will adjust the propeller pitch to maintain that RPM. There is no difference in that respect to any other MSFS aircraft with a constant pitch propeller?
The turboprop engine model in MSFS is laughable in its current state, on the Kingair and TBM the ITT shoots up and becomes as hot as the surface of the sun, fusing hydrogen atoms into helium when feathering. Weirdly the Ng does not go down when feathering, but the prop speed does go down so there isn’t a gearbox simulated between the compressor and the power section? It seems there is a disconnect somewhere…
