No problem with FSX and no need for a plug in.

I used to e-mail with Austin back and forth about this issue a few years ago already.....but maybe sooner or later it will work.

In the meantime I will look for a prop plane instead of the MD-80 for an 'interim' project I think as x-plane is still the sim with the most realistic 'feel'.

 

Looking forward to trying your Prop in X-Plane.

No problem with FSX and no need for a plug in.

I used to e-mail with Austin back and forth about this issue a few years ago already.....but maybe sooner or later it will work.

In the meantime I will look for a prop plane instead of the MD-80 for an 'interim' project I think as x-plane is still the sim with the most realistic 'feel'.

 

Out of curiosity, I did try this earlier today, and found that actually the thrust is NOT linear in the jet engines. I even tested in my next project and performance was also non-linear.

Then I found this statement at x-plane.org made by Brett Sumpter.

http://forums.x-plan...96

 

 

 

"Sure you don't have a plugin installed messing with that?

 

Can't pull the exact numbers now but checking one of the default heavy jets after your earlier post I definitely wasn't seeing anywhere near 50% thrust at 50% N1. "

 

I am definitely interested in your figures and tests, what engine settings you used/added in Planemaker, (as you may be missing something important when modelling your own engines), because if you are seeing a linear throttle/thrust relationship, you must be doing something VERY wrong.

 

Just to add, I got a few figures for you from the default 747-400 in XP10. 50% throttle lever position outputs 68% N1.

60% throttle position outputs 81% N1

70% throttle outputs 93% N1

I'm not sure if this is accurate as I don't fly 747's or KC-10's, but it sure isn't linear.

 

Now, comparing that to a well known 747-400 in FSX, here are the following results.

50% throttle position=72% N1

60% throttle position=88% N1

70% throttle position=102% N1

 

Default FSX 747-400

50% throttle=72% N1

60% throttle=93% N1

70% throttle=104% N1

 

So which one is right?

One thing is certain. None of them are linear.

Well, I am sorry but for the perfect thing we will have to wait for Aerowinx PSX...

 

So which one is right?

Just to add, I got a few figures for you from the default 747-400 in XP10. 50% throttle lever position outputs 68% N1.

60% throttle position outputs 81% N1

One thing is certain. None of them are linear.

 

If you would take your time and plot the numbers for every 10% of thrust lever position on a sheet of paper you will see that it is linear. Plain & simple.

50% thrust lever (xplane10 default 747) = 68% N1 (67% N1 on my install).....33% is the idle N1 hence 67% N1 are exactly 50% of the available RPM.

At the 50% thrust lever position you get 30000lbs (should be around 12-15000lbs IRL) of thrust which is very close the 50% of the available 63000lbs at 100% RPM.

And could you PLEASE stop that stupid FSX vs x-plane comparison once and for all.

 

Furthermore u r completely missing the point. It's about thrust vs thrustlever/N1 and not thrustlever vs N1.

If you would take your time and plot the numbers for every 10% of thrust lever position on a sheet of paper you will see that it is linear. Plain & simple.

 

I did. 50%, 60% and 70%. They are NOT linear.

 

50% thrust lever (xplane10 default 747) = 68% N1 (67% N1 on my install).....33% is the idle N1 hence 67% N1 are exactly 50% of the available RPM.

At the 50% thrust lever position you get 30000lbs (should be around 12-15000lbs IRL) of thrust which is very close the 50% of the available 63000lbs at 100% RPM.

 

At 50% throttle, I let it stabilize at exactly 68%. Hence, non-linear. The following figures, at 10% increments are even further proof that it is non-linear.

 

And could you PLEASE stop that stupid FSX vs x-plane comparison once and for all.

 

Why? You're the one coming in here making a statement against X Planes engine modelling and you were proven wrong. I just decided to try FSX as well to see if the engine modelling in that was indeed non-linear...and it was. I wanted to see if you were correct, and you were.

I don't know why you're getting so bent out of shape. It's not personal (although you seem to be making it personal). It was a simple comparison between 2 flight sims that I have on my PC. Nothing stupid about it. I actually like learning more about FSX.

 

EDIT: One more small, tiny bit of info. If X Planes engine modelling was, indeed, linear, as you say it is, and with the difference between idle throttle position and displayed N1 being 17%, that means at 100% throttle position, the N1 should be 117%. Sorry to say, but this is not the case. At 100% throttle position, N1 is exactly 102.6%

So, to conclude, it appears that at idle up to 60% throttle position, for some reason on your setup, it is perfectly linear with the N1 being at 67%. On mine, it is out by 1% N1 (68%). As throttle increases, N1 increases up to a certain point, and then starts to fall back to a near equal throttle/N1 relationship.

Definitely non-linear.

 

Apologies for the further FSX/XPlane comparisons (I certainly don't mean to offend you or making you upset over it), but at full throttle in FSX, N1 is at 110.4%. Much closer to linearity than X Plane.

simply forget it.....u apparently don't get.

Or one last try. use a pencil, a ruler and a sheet of paper.

Now lets start at the 0% thrustlever position on the horizontal axis and stop at the 100% position.

On the vertical axis plot the N1. starting at 33% (idle) at the 0% thrustlever position and stop at the 100% thrustlever and N1 position.

Now connect all the dots from the various thrustlever and N1 positions......

If that's linear, that's ok because again and again, it's about thrust vs thrustlever/N1.

Now do the same with the thrust on the vertical axis

If that's linear, or close to linear it's wrong.

 

I thought you were banned at x-plane.org so I felt really save over there. oh well.

simply forget it.

 

Gladly.

Have a great day, Bernt. And I look forward to getting your first X Plane project!

Keep on smilin', buddy!

:good:

I beileve there is yet no way to properly define a free-runninf turbine in Planemaker. Not a big deal of course...

 

There might be...in the sense that plane-maker has a "free-turbine" mode. For the MU2, I had / have to do a plugin to make it just right...but for the C90, I pretty much didn't care but as I am tuning up the KingAir and Baron for the next release, I'll look into it. There may be something there I haven't looked at.

 

Tom Kyler

Laminar

V10 aircraft

V10 scenery

If you think it's a bug send it to Austin at:

http://dev.x-plane.com/support/bugreport.html

If you think it's a bug send it to Austin at:

I've worked for Austin for about 2 years now and never knew that link. Guess I just got spoiled emailing/skyping him directly. Noted on the link ;)

 

 

So PT6 guys help me out. When you lower the prop speed, I assume you are also maintaining a constant torque / fuel flow. So we should see a reduction in prop speed, but consistent fuel flow / torque yes?....so probably an increased blade angle at lower speeds?

That's nice to know - thanks!

 

Anyway, of course the Baron58 is not a turbine one... ;-)

 

 

I pretty much didn't care but as I am tuning up the KingAir and Baron for the next release, I'll look into it

 

On a PT-6, since it is free-running, for a given "throttle" setting, reducing RPM (pulling on the lever) using the Prop lever will increase torque, and increasing RPM (pushing on the lever) will reduce torque. Fuel Flow will stay unchanged.

 

BTW, the following simulators model this type of turbine very acceptably: ELITE v8 (you can download the demo and run it to check, using Insert/Delete for "throttle", Home/End for Prop and PgUp/PgDn for Condition), Fly!2 (it has a Kingair b200) and ASA On-Top v9

 

 

So PT6 guys help me out. When you lower the prop speed, I assume you are also maintaining a constant torque / fuel flow. So we should see a reduction in prop speed, but consistent fuel flow / torque yes?....so probably an increased blade angle at lower speeds?

R U sure that this happens with v10 planes as well?

Found out a while ago that the problem is the same with the default Baron which apparently hasn't been changed. Reducing prop rpm causes a reduction in fuel flow but mp remains unchanged.

Same goes for the default C90 where a reduction in prop rpm causes a reduction in fuel flow but the torque remains unchanged as well.

On dedicated v10 planes like the sbach300 (and AFAIK Gorans DC-3) mp (torque)/rpm/ff behaviour is correct.

sorry...wrote torque above when I meant power. Right...lower RPM > increased torque > same power > same FF. Looking into it.

 

 

EDIT: Seems to work reasonably OK for now. Without a comprehensive King Air C90 reference in front of me, it's the best I can do...but you can pull back the prop speed to about 1800 and the FF/power stays generally consistent....perhaps a variation of less than 10 bhp from 1800 - 2000. I'll stick this in the next update and we can iterate through it and make adjustments. I'm sure there is a lot of PT-6 experience around here.

Ok, Thx!

 

I will reinstall xplane10 when the next release is made available :-) and give it a try!

 

This is what makes Xplane10 really worth the "effort"/"buy" - it keeps being updated... and somehow follows users requests :-)

 

Great to have an xplane team dev posting at this forum too

 

EDIT: Seems to work reasonably OK for now. Without a comprehensive King Air C90 reference in front of me, it's the best I can do...but you can pull back the prop speed to about 1800 and the FF/power stays generally consistent....perhaps a variation of less than 10 bhp from 1800 - 2000. I'll stick this in the next update and we can iterate through it and make adjustments. I'm sure there is a lot of PT-6 experience around here.

simply forget it.....u apparently don't get.

Or one last try. use a pencil, a ruler and a sheet of paper.

Now lets start at the 0% thrustlever position on the horizontal axis and stop at the 100% position.

On the vertical axis plot the N1. starting at 33% (idle) at the 0% thrustlever position and stop at the 100% thrustlever and N1 position.

Now connect all the dots from the various thrustlever and N1 positions......

If that's linear, that's ok because again and again, it's about thrust vs thrustlever/N1.

Now do the same with the thrust on the vertical axis

If that's linear, or close to linear it's wrong.

 

 

After doing it in my head, I decided to use your pencil and paper method...just to make sure my results that I got in my head matched the results I got on pencil and paper. Very interesting results. Still non-linear on all counts.

Instead of me posting my results, I'm sure you can use the method you described if you wish to verify it.

I won't comment on what I found out about FSX's engine model, seeing as you get so offended by any FSX/X Plane comparison.

 

I thought you were banned at x-plane.org so I felt really save over there. oh well.

 

I didn't even know you felt threatened by me.

I continue to constantly learn new things about you, Bernt.