Sign in to follow this  
onduty

No, it is not a Garrett

Recommended Posts

Hi Guys,

 

No, it is not even a turboprop behaviour. Flysimware advertise this product as "custom coding for the Garrett TPE331 turboprop engines and sounds for the most realistic Garrett simulation ever produced."

When I purchased the C441 I was looking forward to it with great expectations, especially the engine behaviour. To my dissapointment I found that it is just a basic, unrealistic FSX turbine engine. I.e: During climb, the EGT decreases with altitude and T/Q remains constant. This is just the opposite to real world! In FS history a couple of addons were able to circumnavigate that basic FS coding. But not Flysimware.

I' ve checked a couple of Flysimware MU-2 vidoeos on you tube and to my dismay the engine parameters still behaved the wrong way.

Now, I do not understand why it is the "most realistic Garrett"?

It would be interestnig to have that "experienced RW MU-2 beta pilot's" opinion on that.

 

Cheers,

 

Tamas

Share this post


Link to post
Help AVSIM continue to serve you!
Please donate today!

I understand what you are saying in regards to the temps not rising with alt, and I agree it would be nice if it did, but just to be clear...the torque does not stay constant and does drop with gain in alt.

 

Also regarding torque, keep in mind they have not modeled the ability to run this plane with anything less than 100% rpm.  So you won't see the torque rise from a drop in rpm's as it should.The real plane is typically run at either 96% or 100%.

 

I personally believe that when they used the term Garrett simulation that they were referring only to the engine start-up effects. As far as their experience with the mu2 I'd say that's mostly over-hyped marketing IMO.

 

...to be fair, however...the coder/owner of Flysimware has shown that he is willing to come back and fix certain aspects of his work as his skills progress and time permits...so there's always the possibility these issues may be rectified at some point in the future.

Share this post


Link to post

Actually the torque on teh MU2 does decrease with altitude Temps may need to be looked into though.. Found this good video gives one good perspective of engine . Also nice grass short field take off.

 

Share this post


Link to post

From what I can see from teh videos it behaves as it should. RPm is either grnd idle(taxi) or flight 100%,.  It ceratinly doesnt change in videos. Torque does decrease with altitude and I dont think you can even get 90% at Fl250, mind you at that altitude the book says 65% torque. The book I thinks says 100% below FL120. Even though temp varies with engine rpm i cant tell what it is supposed to do, though in other turbine as mentioned I believe it does increase as teh air gets thinner therby requiring power reduction. Must review more videos.

Share this post


Link to post

Further looking , teh condition lever is either 72 to 74% RPM at taxi, 96% at Minimum Cruise, 100% TO and Land. In teh flight videos, teh EGT was aroun 62 @ FL250 with 60% Torque but that is air trmp dependent.

Share this post


Link to post

Hi Dear Guys,

 

Many thanks for your replies. In my original post I simplified a bit to be short enough.

I don't have to check videos, my experience/opinion is based on rw encounters with turboprop aircraft.

A basic turboprop engine with "simple" hydro-mechanic engine controls (not with that fancy FADEC) behaves like

this (no matter if it is a Pratt or Garett):

1. During a steady state climb with a fixed throttle setting the T/Q drops gradually while the EGT (ITT) remaining basically steady.

2. Since you have not reached max. EGT at the early stage of climb, you can recover the T/Q drop by gradually advancing the power levers. By adding more fuel to the engine, EGT will increase of course!

3. At a certain altitude you will reach redline or max. EGT (the engine "temps out"). After this point you cannot

advance the power levers further and the T/Q will drop eventually (the engine will lose power).

4. Yes, you can check inflight videos and will see the typical cruise scenario: the T/Q is around 50-70% and the EGT is near the redline limit.

 

That's all in a nutshell and I expected roughly this behaviour based on the Flysimware promo text.

I'm sure that Flysimware's beta pilot with all that MU-2 experience will confirm my short description.

Anyway, in FS world I only know two addons that come out with proper turboprop handling: the good old Aerosoft/digital Aviation Piper Cheyenne and the F1 King Air.

 

Cheers,

 

Tamas

Share this post


Link to post

If I remember correctly, the Flight1 Kingair does not behave realistically either...in that it has no increase in torque as you drop the rpm, and it should. The DA Kingair was probably a better engine sim that the F1 version is. Flight1 is all about profits, where DA was all about passion.

 

As I already said above...no one can argue that the toque and temps in this mu2 do not perfectly represent how it behaves in real life, and yea maybe their webpage over-hyped your expectations a little bit...but that said it's still the best mu2 simulation we currently have for the MS platform and for fans of the type it can sure be an interesting and fun ride :-)

Share this post


Link to post

Some of these errors could be explained by the poor state of weather modelling.

 

Tamas, to give qualification to your statements, please provide the sim, version, your choice of aftermarket weather engine and bets of all a specific flight scenario for others to test. Otherwise how do we know the problem isn't with your system, or another addon?

 

The reason that I ask is that your knowledge of Garretts is flawed. The TPE's engines on the Moo modelled here are flat-rated. A flat-rated turboprop will hold a constant torque until the limit of its rating is reached, usually defined by ITT/EGT or RPM limitation.

 

IIRC (and I'm not in front of tech docs at this time) the Maximum Recommended Cruise Power chart for the TPE331 shows the power setting is torque limited to 1738 ft. lb from sea level to about 16,000 ft. From there the max. power setting is limited by hitting the max. EGT of 450 C - and that can be dependent on weather factors not just engine operation parameters. 

 
Everything I've read concurs with your notion EGT for Garrett engines rises with altitude and becomes the limit for setting power- but torque or Vmo isn't a factor and should remain constant until the `critical altitude` (he says, mixing his technical metaphors). If that is the case then torque should remain constant as set rather than wander downwards until passing 16K.
I have no idea if this can be properly modelled in FSX/P3D as a number of old air file parameters have been irrelevant and ignored since FS9 days. 
Be happy to be proved wrong, but somehow I don't think I am.
 
While you correctly highlight a FM inconsistency, you are partly wrong in your conclusion. Torque should, I believe, remain fixed in relation to power lever position until a certain altitude is reached, and the PL should then need moving forward to compensate for torque drop, OR back to retain EGT increases within limits.
 
And you missed out on two very good engine models for TP's  - the Real Air Turbine Duke and the daddy - the Majestic Dash 8, which does it's engine modelling OUTSIDE the sim, thereby circumventing the limitations of the internal model, as well as highlighting it.  
 
Marty?

Share this post


Link to post

I agree, this is not a perfect Garrett, but its a pretty good MU-2. And it is active development, making the best MU2 available.

 

And you missed out on two very good engine models for TP's  - the Real Air Turbine Duke and the daddy - the Majestic Dash 8,

 

The pt6 modeling on the realair tduke v2 is amazing, I believe they had to use an external module outside of the fs framework to get it that good, check it out if you haven't already. I'm told that the majestic q400 is even better, engine wise.

Share this post


Link to post

And for FSX at least, the Garrett simulation provided by the PMDG J41 kicked DA and F1 into another county. 

Share this post


Link to post

Ok Guys,

 

I really enjoyed this discussion, your points are taken, but I still strongly believe that my basic description of the engine management of a simple turboprop is correct.

Yes, I have "flown" all the models of various FS dev.teams mentioned here except the PMDG J41. The reason is that I could not find rw manuals especially performance manuals on the J41. Pitty! I like to fly "by the book" even is FS world.

Coming back to the MU-2: I am convinced now that it is the best MU-2 for FSX, I will buy it to have a closer look. It is a really unique, high performance, demanding aircraft .

Thank you all,

 

Tamas

Share this post


Link to post

Funny thing is one of the oldest FSX turbopros(PA31T  Piper Cheyene) looks pretty well moddelled and that plane is 2008 vintage. Considering its age has one of the nicest VC,s.

Share this post


Link to post

Thanks Louis, I' ve got it, plus a RW POH/AFM from the net. So, I'm prepared to study!

Mjrh, agreed, it is surprisingly good.

 

Cheers,

 

Tamas

Share this post


Link to post

Hi everybody,

 

Once having the opportunity to give Flysimware MU-2 a brief try in a friend's system, knowing other sim products, having consulted the real life Mu-2B-60 Marquise Flight Manual and some technical posts on the internet about this great aircraft... let me say that:

First (already discused in the forum, so not going in too much detail):
Contrary to what Flysimware claims, the turbine model is really incorrect in regard to Torque and Temperature, and also due to the fact that it's not possible to stablish correct power settings from the 100% down to 96% range as needed specifically for cruise, descend and holdings... according to tables contained in the real Aircraft's Flight Manual.

Second- there is an animation issue concerning the elevators trim tabs. As for inflight trimming purposes, a Trim Tab is actually required to move in the opposite direction to that of the control surface it is connected to.

So, in Flysimware's  MU2, for an inflight Nose-Up trimming, Tabs are incorrectly modelled moving upward -when they must move downward to force elevators upward and hence lower the aircraft's tail resulting in a nose-up attitude. Logically enough ...for trimming Nose-Down... just the opposite as described is observed.  In case of disagreement, then it can be easily verified just observing another quality product... or real life aircraft !

The problem here is not the issues themselves (if being able to fix them and not leaving the product as it is now), but Flysimware's claiming what actually is not true when advertising the product as "the most realistic Garrett turboprop simulation aircraft on the market".  It`s then when the above mentioned issues become unacceptable... specially when looking at the competence -RealAir, Majestic Software, PMDG... where more than one virtually perfect model, by far superior in flight dynamics refinament, systems, turbine behavior and aesthetics- can be found... one selling for just € 32.95 !

Hope Flysimware be able to fix the aforementioned issues, then the product will worth the price and become a good virtual version of the great and venerable Mitubishi Mu-2 Marquise.

Sorry for any mistakes in my english....
Cheers,

Carlos
 

Share this post


Link to post

I've dealt with your trim tab assertion in your dedicated topic. As for the Garrett comments, you really should read what comes before. We've covered the representation of the relationship between torque and EGT quite adequately. Your comments look like you haven't understood the concepts being discussed, or have simply rushed in with your own viewpoint, based on a few minutes with the product on a friends system. Things we've already covered.

Share this post


Link to post

 

 


From what I can see from teh videos it behaves as it should. RPm is either grnd idle(taxi) or flight 100%,. It ceratinly doesnt change in videos.

 

If you pay close attention to the video (advance to minute 6:15), you will clearly see how the pilot disconnects the prop synchrophaser, release friction lever, advance condition levers full forward to their T.O./Land position and finally re-adjust friction lever.

Even when engine normal operating speed is stablished between 96% and 100% RPM,  100% is the parameter for takeoff and landing, and below 100% (96% minimum) as appropiate for the rest of the flight according to prevailing conditions and particular needs.

Cheers
 

Share this post


Link to post

Not sure you can actually define anything from that video - it's episodic and does not cover the whole flight so you have no way of gauging where and when the condition levers may have been pulled back - judged by the earlier armsfolded-at-cruise the condition levers are still full forward at that point. Could easily have been to expedite a descent at the behest of ATC, or to match a particular STAR, or simply the whim of the PIC. Why are you using non-instructional videos to reference what is a non-issue ? 

 

Not sure what point you are trying to make here ? Is this your standard operating procedure when you fly your Marquise ? 

 

There are differing ways to fly the same aeroplane even within the standard operating regime. 

 

Here's a PIREP one that doesn't reference the condition levers, except for checking for full forward for take off.

http://www.airaffair.com/Library/Archive/Part1/mu-2_pilot_report

 

The main reason for retarding at cruise was originally to reduce the noise levels in the cabin. Early models were know  to be LOUD. The later models with the -10 engine and 4-blade props are noticeably quieter.

Share this post


Link to post

Then this may be of interest

 

http://eastaire.us/newchecklist.pdf

 

And don't forget to ping Dave (hangar) for a copy of his 1.7 FDE amendment 4c. 

 

You will get an appreciation of what the Moo can Doo...  :P

Curious what is 1.7 FDE amendment 4c ?

Share this post


Link to post

Not sure you can actually define anything from that video - it's episodic and does not cover the whole flight so you have no way of gauging where and when the condition levers may have been pulled back - judged by the earlier armsfolded-at-cruise the condition levers are still full forward at that point. Could easily have been to expedite a descent at the behest of ATC, or to match a particular STAR, or simply the whim of the PIC. Why are you using non-instructional videos to reference what is a non-issue ? 

 

Not sure what point you are trying to make here ? Is this your standard operating procedure when you fly your Marquise ? 

 

There are differing ways to fly the same aeroplane even within the standard operating regime. 

 

Here's a PIREP one that doesn't reference the condition levers, except for checking for full forward for take off.

http://www.airaffair.com/Library/Archive/Part1/mu-2_pilot_report

 

The main reason for retarding at cruise was originally to reduce the noise levels in the cabin. Early models were know  to be LOUD. The later models with the -10 engine and 4-blade props are noticeably quieter.

@ louisdecoolste:

 

It's not a good habit rushing to respond about any topic without thinking a bit first.  I would suggest you stop always arguing against everybody and pretending you are always right while the others

 

are wrong. Now:

 

1-Read the post again... check the video from minute 6:15 forward....The video is perfectly clear for some observations.

 

2-Forget about STARs or whatever, it's mentioned in the video itself it´s just a straight-in VISUAL approach...pay attention.

 

3-You do not need to see the whole flight to see pilot`s actions along final approach...or do you?

 

4-You say: "Not sure what point you are trying to make here ?"  ... check quotations again... "mjrhealth" stimates RPMs do not change in video. I just point out there is a subtle change in RPMs at

the moment the pilot acts on the Condition Levers and push them forward to T.O./Land position in final approach...

 

5-You say: "The main reason for retarding at cruise was originally to reduce the noise levels in the cabin."  ... No my friend, sorry but no. Reduced noise level is a bonus you obtain from the main reason which is FUEL CONSUMPTION -Read the aircraft manual.  Fuel consumption varies in accordance to power settings at altitude and prevailing conditions, and are provided as Torque/RPM combinations which adequately managed can translate into more range for a trip, or more endurance for holdings ... two good reasons.

 

Cheers

 

Share this post


Link to post

Fuel consumption is better adjusted by retarding the power levers. Or flying at a more economic height, or utilising a tailwind. If you think a scant change in prop rpm can make a significant difference in the flying characteristics, you are not getting what we are trying to explain to you. IT DOESN'T MATTER. It's subtle in your own description because its imperceptible. So what significant difference to fuel consumption do you think it makes ? And again, as we never saw when the pilot retarded the CL's you are the one making assumptions.

There are plenty of things that DO matter that we wish the developers to fix, so why to insist to force this complete non-issue, when its already been explained by the developers ?

 

I'm sorry, I missed the part where you told us about your experiences in the real thing that lead you to this foregone conclusion that this is something that needs modelling ? How many hours do you have in this aircraft, the -60 Marquise ? If not, then what are your experiences behind Garretts ?

 

The developers explained why they didn't, I've provided examples where the lever is simply advanced to 100% and left there, and you regard an imperceptible change in RPM as something that is necessary for the correct interpretation of the flight model. We don't. There are many other important aspects of the Garrett modelling that need to be addressed first. The torque settings are more important to the economic operation of the aircraft than RPM. This is a geared turbine, so there is ALWAYS going to be a proportional relationship between prop speed and power setting - the reason that the range of adjustment is so small (100-96%) at a cruise power setting is that is all there is. This is not a PT6 nor any other free turbine.

 

If you look at this actual checklist 

http://eastaire.us/newchecklist.pdf

you will see - or rather NOT see - any reference to adjusting CL for cruise flight. Again, its optional for the real world use of this aircraft. 

 

And more range for a trip makes no sense to me. Can you explain what you mean by that ? A trip is a set distance, planned for with appropriate diversionary fuel. If you have a fuel problemy, well that's just very poor planning, or an emergency.

Share this post


Link to post

Fuel consumption is better adjusted by retarding the power levers. Or flying at a more economic height, or utilising a tailwind. If you think a scant change in prop rpm can make a significant difference in the flying characteristics, you are not getting what we are trying to explain to you. IT DOESN'T MATTER. It's subtle in your own description because its imperceptible. So what significant difference to fuel consumption do you think it makes ? And again, as we never saw when the pilot retarded the CL's you are the one making assumptions.

There are plenty of things that DO matter that we wish the developers to fix, so why to insist to force this complete non-issue, when its already been explained by the developers ?

 

I'm sorry, I missed the part where you told us about your experiences in the real thing that lead you to this foregone conclusion that this is something that needs modelling ? How many hours do you have in this aircraft, the -60 Marquise ? If not, then what are your experiences behind Garretts ?

 

The developers explained why they didn't, I've provided examples where the lever is simply advanced to 100% and left there, and you regard an imperceptible change in RPM as something that is necessary for the correct interpretation of the flight model. We don't. There are many other important aspects of the Garrett modelling that need to be addressed first. The torque settings are more important to the economic operation of the aircraft than RPM. This is a geared turbine, so there is ALWAYS going to be a proportional relationship between prop speed and power setting - the reason that the range of adjustment is so small (100-96%) at a cruise power setting is that is all there is. This is not a PT6 nor any other free turbine.

 

If you look at this actual checklist 

http://eastaire.us/newchecklist.pdf

you will see - or rather NOT see - any reference to adjusting CL for cruise flight. Again, its optional for the real world use of this aircraft. 

 

And more range for a trip makes no sense to me. Can you explain what you mean by that ? A trip is a set distance, planned for with appropriate diversionary fuel. If you have a fuel problemy, well that's just very poor planning, or an emergency.

 

So...you are 100% sure there is no reference about adjusting Conditon Levers...

Once again, READ before responding to anybody...

 

In "YOUR" New Checklists - Section 5/Normal Procedures  (.pdf document page 98):

 

CLIMB (18000') / CRUISE

Power ............SET AS REQUIRED (96% RPM TO 98% RPM)

 

 

Also READ the AFM (Aircraft Flight Manual) Section 5 Normal Procedures:

 

CRUISE CLIMB (AFM 5-17)

RPM ......  96% to 98%

EGT ...... 650ºC MAXIMUM

Torque... 100%  MAXIMUM

 

CRUISE (AFM 5-18-1)

Power ............SET AS REQUIRED (96% RPM TO 98% RPM)

 

 

Sorry but, do yourself a favor and stop asking others to demostrate their knowledge and expertise... it's no good for you, as you are the one who need it most.

 

Cheers

Share this post


Link to post

98% RPM is the delivered RPM from a PL setting that is at max cruise, with CL full forward...

 

and the claimed difference in SFC, to attend to your range increase claims, is a change form 0.652 to 0.650 lb/hp/hr, according to the same AFM you seem able to quote at will, but not quite understand. 

 

Enough, The developers aren't changing this aspect, and you are the only one pursuing it. . 

Share this post


Link to post

98% RPM is the delivered RPM from a PL setting that is at max cruise, with CL full forward...

 

and the claimed difference in SFC, to attend to your range increase claims, is a change form 0.652 to 0.650 lb/hp/hr, according to the same AFM you seem able to quote at will, but not quite understand. 

 

Enough, The developers aren't changing this aspect, and you are the only one pursuing it. . 

Again... you're absolutely wrong....

but, yes..good enough. I won't continue wasting my time with you any more.

 

Cheers

 

Share this post


Link to post

In the King Air 200 with PT6-42A's in it, which is flat rated to 850 hp, the Torque does decrease with an increase in altitude. The simple explanation for this is, the RPM's stay the same, but as the air density decreases, the props are not pushing as hard against the air around them and it is easier to maintain the 1900 RPM prop rpm (if commanded, and 1900 is what we use in climb).  You then increase the throttle to maintain desired torque, or to maintain the maximum amount of power to help climb the aircraft. This occurs until you either temp out, or you reach your N1 limits (varies on outside temperature and altitude).  So yes, a turboprop will gradually reduce torque as it climbs and ITT/EGT/TGT will remain the same until you command more fuel for the engine by moving the throttles forward.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this