What he means is that on a PT-6 Engine changing the Prop Lever shouldn't change the Fuel Flow of the Engine. Don't ask me why. They're the knowledge ones!

 

 

What he means is that on a PT-6 Engine changing the Prop Lever shouldn't change the Fuel Flow of the Engine. Don't ask me why. They're the knowledge ones!

 

Exactly!

 

Because the throttle only feeds the gas producer, and the prop shaft is independent. 

 

The air leaving the turbine will make the compressor fans attached to the prop shaft turn, but they aren't directly connected, so, contrarily to a non-free turbine, varying the prop RPM will not affect FF...  (the description is being written without the right terms... I know...)

Oh noes, you guys might have just ruined the Turbine Duke for me! An exaggeration really, but the change in FF in Real Air's Dukes PT-6 has confused me for quite some time. Yet everbody and their mother said that their engine modelling was the best out there so far, with the exception of the geared turbines on the J-41, so I eventually stopped being bothered by it and thought, well maybe I'm just misunderstanding something: Maybe the fuel controller does something, and the FF really should change. Starting to look like a case of Ignorance can be bliss! Good to know, anyway. Or maybe not so good to know.

 

Surprised to hear that view of the Carenado. My enthusiasm for the brand new F1 b200 is currently in a holding pattern because of a problem that some have reported, (hopefully soon fixed), but that caused me to go over and start reading in the Carenado B200 forums pretty extensively. As usual, I got the overall impression that the plane was only so-so. But now Brett comes in, seems to know what he's talking about, and declares it the best, better than the Duke even. That is not a common opinion

Hard to make decisions on what to buy these days, and for turboprops even harder!  Really, the Carenado B200 is that good? Flight model performance compared to the real airplane, systems modelling too? I've generally avoided Carenado airplanes since the days of the Piper Cherokee, but now I hear this...

Understand, thanks for the explanation?

 

Martin

I don't know what type of turbine equips the Duke!  The J41 as far as I know is not free, and if so, FF should vary...

KingGhidorah:

 

"Surprised to hear about the Carenado. I was reading in the Carenado B200 forums pretty extensively lately, and got the impression that the plane was only so-so. But now Brett comes in, seems to know what he's talking about, and declares it the best, better than the Duke even"

 

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I was kinda surprised myself.. as Carenado (as mentioned) is hit-n-miss on many model aspects. I think the beating they took for the Caravan performance/engine modeling hit home... 'cause this thing is amazing. The model detail and texturing are world-class (in and out).. the turbine modeling is better than PMDG.. all aspects.. startup, thrust/torque via spool up/down.. even the thrust-reversing works smoothly, and allows for self-pushback (be ready on the brakes when returning throttles to idle). The icing on the cake are the "3D" sounds from the VC. There's a torque-tied, deep hummm.. AND an RPM-tied prop whine.. independent of eachother, and there's little if any annoying, abrubt transitions.

 

Performance ala takeoff rolls, climbs, cruises and descents are pretty close to real numbers.. but the control surface effectiveness (and axes stability) do need tweaking per your control hardware, as with almost ANY model.

 

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I don't know what type of turbine equips the Duke!  The J41 as far as I know is not free, and if so, FF should vary...

 

 

 

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It shouldn't vary as directly as a piston engine, because FF is still controlled by a type of "valve", as opposed to a throttle-body/carb(or injected) sytem, where pistons "suck" the fuel in, and the throttle "throttles" manifold pressure.

 

What's really realistic about the J41, is the you have to set the props to "beta", else their mechanical conection to the turbine offers damaging resistance during startup.

Brett_Henderson, on 17 Jul 2013 - 11:47 AM, said:

Brett_Henderson, on 17 Jul 2013 - 11:47 AM, said:

 

Performance ala takeoff rolls, climbs, cruises and descents are pretty close to real numbers.. but the control surface effectiveness (and axes stability) do need tweaking per your control hardware, as with almost ANY model.

Curious what changes you made to the aircraft.cfg. I know you're a flight instructor, and also have made some freeware aircraft, so I assume you are talking about changes to obtain the proper feel of the controls, and have some credibility in this area. I have Saitek yoke and pedals, and they are assigned through FSX, with whatever sensitivities FSX gave them by default. What did you do and why?

 

Obviously I don't have the aircraft at the present time, but if it sounds do-able, I just might go for it. Definitely have the itch for a new plane.

 

Also, if you could, tell me what you think the major flaws or ommisions are, so I don't have to find out the hard way and be p.off.

Interesting about the PT-6 fuel flow.   I found some performance data from Raisbeck and compared with F1's data.  Looks identical, probably where F1 got the PT6A-52 info from since their King Air is modeled on a Raisbeck edition.  Here is the comparison between 1600RPM and 1800RPM at ISA conditions.  According to these charts, fuel flow is mostly lower at 1600RPM, except at FL330 where they are the same which is interesting.

 

 

 

Here is Raisbeck's performance chart if you want to look at other performance numbers.

http://www.enhanced.aero/pdf/performance_raisbeck.pdf

I have a CH yoke/petals.. with almost any model, I need to reduce pitch response/sensitivity.. easiest way is to slightly decrease elevator effectiveness, and slightly increase pitch stability.. Roll and yaw are usually fine, but slight tweaks there, too. are common.

 

No major flaws, but the textures are a handful to render. They're 2048X2048... the fuselage is cut into thirds, each using a big chunk of the 2048 "width". IOW the fuselage is more like a 5012X1024 texture. If you haven't "peeked" an outside view for a period of time, you get to see the model get painted for a fraction of a second. Prob not a problem for the +4ghz machines out there, but a bit of a nuisance for my old rig (3.8ghz).

 

Also, and old MSFS bug.. if your saved, default flight is not the B200, it might load with the fuel valves "off".. so you have to load something like the defaul Baron, and open both selector valves..

 

The AutoPilot is something interesting.. not sure how true it is to real-life, but you'd get the hang of it.

 

Interesting about the PT-6 fuel flow.   I found some performance data from Raisbeck and compared with F1's data.  Looks identical, probably where F1 got the PT6A-52 info from since their King Air is modeled on a Raisbeck edition.  Here is the comparison between 1600RPM and 1800RPM at ISA conditions.  According to these charts, fuel flow is mostly lower at 1600RPM, except at FL330 where they are the same which is interesting.

 

 

 

Here is Raisbeck's performance chart if you want to look at other performance numbers.

http://www.enhanced.aero/pdf/performance_raisbeck.pdf

 

 

Note that those are power settings.. where you target a torque and an RPM.. meaning, if you changed from 1800rpm to 1600rpm, you'd have to also reset torque (throttle) to get the proper set of numbers.. this would change FF.

This bodes well for Carenado's 1900D. I wonder how the MilViz King Airs will fair? Can't wait.

On post #145:

 

Changed, "rudder", to "elevator".. **blush**

 

 

Note that those are power settings.. where you target a torque and an RPM.. meaning, if you changed from 1800rpm to 1600rpm, you'd have to also reset torque (throttle) to get the proper set of numbers.. this would change FF.

 

True, so, if at a given altitude you set you throttle and RPM for a given power setting, note your FF, and then from there start reducing / increasing Prop RPM, the FF will be fixed.

 

As Brett points out, on those charts to get the same TRQ for the given RPM you had to make adjustments to the throttle, which naturally alters the FF, and that's why it's values between charts, for the same RPM and ISA and TRQ will show slightly distinct FF :-)

 

This and other facts are why ELITE albeit being so crude in terms of graphics, is still mi preferred GA simulator. Every aircraft in my Premium package can be operated as per the manual, and within the normal flight envelope, they all behave extremely realistically :-)

Well, Fuel Flow may be off, but it's a small trade off for a vastly superior product overall, so you can keep your Carenado B200, and I'll keep my F1 B200. :wink:

 

I guess overall perspective comes into it for some of us simmers.

 

Don't get me wrong; I rivet count occasionally, in the areas that are important to me, but I would never rate the Carenado B200 over the F1 B200, due to the FF accuracy, or lack thereof.

Well I learn something new every day lol. I don't have a turbine rating and never took any turbine groundschool courses. And here I was recommending the F1 King Air for those looking to get a Turbine rating...oh well, such the life of an FS simmer.

 

I suppose due to the sheer difficulty of accurately programming a turboprop within the confines of FSX, each developer's approach in modeling is going to have tradeoffs, be it Aerosoft, PMDG, RealAir, F1, Carenado, Majestic...etc. Kind of like the turn coordination issue...you either have accurate TC or accurate side slipping, difficult to have both done accurately in FSX.

 

I know A2A isn't doing a turboprop anytime soon but I would think accusim might be able to do a good job being that it is programmed completely outside the realm(limitations) of FSX.