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scotchegg

J Rollon's Mentor

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Looks great - except for the tires that run flat on the pavement!

I believe there's a way to fix that in plane maker. Something about terrain elevation corrections if I recall and mapping runways to terrain ... but I haven't the foggiest where that information is! :)

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Really not sure. Looks great but then again it seems to be an update of a model originally made in 2010? $30 seems a bit steep.

 

Maybe if it gets discounted...

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I have it and like it,It's one of the most beautifully aircraft done texture wise,It's not really in depth system wise as it's getting a little dated.But it's a very nice aircraft.

T34CMentor_Lukasz_20.png

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Couldn't resist it any more so bought it last night. Only to wake up this morning and find the B25 I'd been waiting for had just been released :angry: :lol:

 

Great little plane texture wise - the cockpit reflections are great and really help the immersion.

 

However I'm finding it a real pain to trim. Even at lower power settings with fuel in the right tank only and trim for right wing down, it's still rolling to the left! Is that normal?

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However I'm finding it a real pain to trim. Even at lower power settings with fuel in the right tank only and trim for right wing down, it's still rolling to the left! Is that normal?

Of course it isn't normal.....

 

Just an X-Plane physics problem. Torque is present, but X-Plane doesn't deal with forces to override it.

 

I don't even own this one. Have not flown the real one either. Haven't even looked up real pilot reports.

It's just that with a multitude of pilot reports for so many aircraft, that I've read in the last three months.......and not one reference of support for actual "trim, trim, trim, torque roll".........I can say with 100% thought, that no, it's not normal.

 

As far as I'm concerned, X-Plane has formed a new generation of piloting thoughts. It's wrong though...

And, I hope the B-25 does all right. Just spent a few hours looking up pilot reports on that one. Watched a good pre-flight and takeoff video too. Nothing about intense torque. Just rudder.

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Just an X-Plane physics problem. Torque is present, but X-Plane doesn't deal with forces to override it.

 

Torque is present, but real aircrafts always use various devices to counter it: engine cant, differential wing incidence, etc. So the right question is: has the aircraft author tweaked the flight model to account for those effects?

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It's a really fun plane to fly! I've had it for a while now and I really enjoy taking it for a spin every so often. It's a wonderful plane for both beginners and experienced flyers.

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Torque is present, but real aircrafts always use various devices to counter it: engine cant, differential wing incidence, etc. So the right question is: has the aircraft author tweaked the flight model to account for those effects?

It's certainly my impression, that the X-Plane program itself, isn't sufficent enough, to use engine cant, or the force of prop wash, as well as lift itself.........to overcome the torque. So, you use the "torque fix", to lower the torque values, or hidden aileron settings & varying wing incidences to counter the problem.

 

Or, you just fall into the belief, that this is how real airplanes fly, and that I don't have a notion of what I've been complaining about. But then you have to wonder. Would real airplane manufactures just expect you to use drag forming aileron trims, just to save some dollars on counter rotating engines for twins, or contra rotating props for singles? Would you really want to leave the runway, and have the plane seriously dip its wing on every takeoff?

 

We can feel the need for rudder on takeoff, to remain on the runway's centerline. We can feel the need for aileron to counter cross winds. How do we judge a torque value that wants to roll the airplane the second we leave the runway? Thank goodness, in real life, we don't have too.

 

edit: One more observation. I've experienced plenty of torque on the takeoff roll. Usually with a touch and go. The left wheel really pushes down on the pavement. You can see it and feel it. But if it continued at rotation time, I'd say holy crap and abort the takeoff. BTW-- since I have not tried the particular airplane, that this thread addresses........I don't know what effects are actually present, or how strong they are.

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I've actually given up on the "torque fix".

 

It's a very interesting way of fixing whatever is causing that overdone rolling moment on prop aircraft in X-Plane 10, but it doesn't come without side effects, and those side effects reflect themselves on aircraft preformance. Affecting the torque output will turn your aircraft into a rather different one, and if it's a carefully designed model, trying to nail the performance down to the real counterpart figures, that is going to have an impact, and that impact is certainly bigger than the consequences of setting aileron trim manually or, using what I have restarted to use - artificial stability.

 

On one of my preferred twins - the Mu2-J - I decided to use the artificial stability section of Plane-Maker to successfuly set the parameters that allow me to fly the model using what I think should be plausible control inputs, without having to constantly set aileron trim.

 

I am using this same approach with all of the prop aircraft.

 

Strangely the default C172 behaves in as far as that rolling moment goes, better than my reference in FSX, which is the A2A C172. As I pointed out at another thread, the A2A crew which flies two of those for real, confirmed in their forums that the model really has that rolling moment due to engine torque effects, as well as the yaw of course, but that in fact the roll is more pronnounced than the yaw!

 

They ( A2A ) are still fine tuning their prop effects routines that run outside of FSX to override FSX's prop effects based only on torque and p-factor, and not taking into account any spiraling slipstream effects, which A2A is trying to model externally.

 

Asymmetric slipstream effects over the root of the left wing on a CW single prop in X-Plane are evident when we enable the flight model view mode ( CTRL-M ). X-Plane is clearly ahead of FSX in this area and it just needs further tunning from Austin to take into account whatever compensates torque in RL.

 

I will gladly explain my art stab settings for the MU2J to anyone willing to try it.

 

Attached my current settings. The 0.15 on "fraction deflection per degree" can easily be increased to 0.25...  (click on the image to see the whole menu)

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After getting used to it it's not as bad as I first thought. I have no idea if it's realistic but it's actually kind of fun having to think more carefully about fuel allocation and making regular trim adjustments. More involving...

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Strangely the default C172 behaves in as far as that rolling moment goes, better than my reference in FSX, which is the A2A C172. As I pointed out at another thread, the A2A crew which flies two of those for real, confirmed in their forums that the model really has that rolling moment due to engine torque effects, as well as the yaw of course, but that in fact the roll is more pronnounced than the yaw!

When we read these lines, we can certainly begin making some conclusions. But "roll" in a Cessna 172, more pronounced than "yaw"???

 

If that's so, then something is out of wack, rigging wise. Flight instructors will have to start warning students about yanking the yoke to the right, instead of worrying about the right foot on the rudder pedal.

 

One can read a multitude of text on the internet, in which torque is described as nothing to worry about, in these small GA Pipers, Cessnas, etc. The effect is just to small. I've personally flew all of these small Pipers and Cessnas to also know that the effect is just to little to even think about.

 

On a side note: I've developed my mini "non wind tunnel" to check the effects of torque. I was holding a small electric powered R/C plane, with a tube fusealage, lightly with two fingers, as a four way gimbal. With the prop turning clockwise from behind, the plane easily wanted to rotate to the left from torque. With no wind, except prop wash over the wing, it would roll and roll, if it could. The torque effect is certainly strong enough. When I applied left rudder, the airplane actually righted itself to level. This is soley from the prop wash hitting the left side of the deflected rudder. In flight, since this little plane has no ailerons, left rudder will actually roll the plane to the left, since it uses dihedral to initiate a bank with rudder. But.........with no added airflow over the wing in a static condition, it's now the opposite, with left rudder rolling the plane right.

 

My scientific conclusion :smile: The vertical tail and rudder, are overpowering "torque", with prop wash. Even though torque is enough to easily roll the plane, once we add some other forces, it's overrun. And we haven't even added the lift of the wing, yet. In flight, this prop wash, as a slip stream, will be hitting the top of the right wing, the bottom of the left, and left side of the vertical tail. In addition to lift on the wing, these forces will be offsetting torque, that just the slip stream hitting left rudder, was doing itself.

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My scientific conclusion :smile: The vertical tail and rudder, are overpowering "torque", with prop wash. Even though torque is enough to easily roll the plane, once we add some other forces, it's overrun. And we haven't even added the lift of the wing, yet. In flight, this prop wash, as a slip stream, will be hitting the top of the right wing, the bottom of the left, and left side of the vertical tail. In addition to lift on the wing, these forces will be offsetting torque, that just the slip stream hitting left rudder, was doing itself.

 

NIce experiments and I agree with the conclusions.

 

If we take e.g. an RV-6 with 180 hp at 2700 rpm, at full power the engine will produce a left-rolling torque equivalent to putting a 30 lbs weight on one of the _tips_ of the wing.

 

If you'd try to do that, I'd assume that, despite the lift of the wings and other forces, the left rolling tendency would be significant? So if this is the case, the reason you don't feel the engine torque must necessarily be because the propwash differentially hits the various surfaces (plus probably engine cant effects) and compensates the original torque.

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Guys,

 

further to my last post about using, in that particular e4xample, artificial stability to lessen the effects of torque in the X-Aviation MU2-J, without using counter-rotating props ( which is unrealistic ) or messing around with the troque fix ( I couldn't even do it in this aircraft, because it uses sophisticated LUA scripts through Gizmo! ) I would like to add that the best results so far were obtained by setting:

 

 

 

The aircraft when it loads on ground automatically sets aileron trim tab and flaps. You should neutralize the aileron trim before starting your takeoff run.

 

Once airborne, you may use a bit of aileron trim, just a bit, and the aircraft will fly pretty much wings level.  Also, when you neutralize aileron trim and reduce thrust to start your descent, there isn't going to be any tendency for left banking, and the descent will be made wings level!

 

This is, for me, a good compromise....

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Thanks for your second post Jcomm.  I thought I was doing something wrong as I was all over the place with your first one.  The second one has tamed the MU-2 and, for that matter the B-25 I downloaded from .org today.  Now I can fly without wrestling with the controls.

 

Thanks again for your usual attention to detail.

 

John


 

 


This is, for me, a good compromise....

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The second one has tamed the MU-2 and, for that matter the B-25 I downloaded from .org

 

Good to know John ;-)  Thx for the thumbs up :-)

 

It's really very easy to edit any prop aircraft and use the Art Stab section of Plane Maker to set those corrections we would be forced to constantly operate on the yoke / aileron trim, to be done automatically for us.

 

Just like with this particular aircraft, the MU2-J, we just have to pay attention to the possibility of the authors having set trim tabs by default, or a script that sets the ailon trim "magically" before you start flying. In the Mu2 the aileron and rudder trim tabs are neutral ( Control Geometry section of PM ) but the LUA script automatically sets flaps and a bit of left trim when you load the aircraft in the RW! I have a couple of keys assigned to center aileron trim and rudder trim, so I neutralize the aileron trim before starting my takeoff roll in the MU2.

 

I uusally try to use values that still require the use of some aileron trim, within what I consider plausible, having no RW experience on the aircraft.

 

I came back to this method, after trying the usual "fix" of setting CW, CCW on multi-engine aircraft, or applying the "TorqueFix" because I really don't like the feel provided by the first or the effects on engine performance of the later.

 

Using the Art Stab you can set above which speed the system starts working ( in this case I chose it to be above 95 Kias so that it would be effective just a bit bellow Vmc, which is 99 KIAS for this twin ).

 

You can try to set your default Art Stab sliders, those found under Settings / Joystick & Equipment / Nullzone, on the left, for pitch, roll and yaw, between 0% ( full left ) and 100% ( full right ). I am using them at 50%. The linearity sliders on the right side of the screen I set them all full left - Linear.

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All of the "Twins" I have gone there to modify have the same settings, which leads me to believe that the authors do not alter them at all - just leaving the defaults.  I might be wrong, but that's what it looks like.

 

John

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All of the "Twins" I have gone there to modify have the same settings, which leads me to believe that the authors do not alter them at all - just leaving the defaults.  I might be wrong, but that's what it looks like.

 

John

 

Yes John, true that most authors chose to use realistic parameters. This is maybe the best solution because if some day Austin corrects whatever is still not totally correct, their aircraft will not behave in a weird way.

 

Other authors use the CW . CCW tweak too.

 

But the Mu2 is peculiar in that it uses Gizmo to automatically set a few degrees of left aileron trim ( the two powerful turboprops are CCW on this one ) when you select it from the Aircraft menu and start at the rw. It also automatically sets 2 points of flaps. With the Art Stab tweak you should not forget to neutralize the aileron trim before the takeoff run.

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Correction on the above... When I opened the Carenado C-340, I found that the Art Stab had been tweaked. They had seemed much better than the others anyway, but I was just looking around and left them the way the author had designed them.

 

John

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Correction on the above... When I opened the Carenado C-340, I found that the Art Stab had been tweaked. They had seemed much better than the others anyway, but I was just looking around and left them the way the author had designed them.

 

John

 

I don't have the C340, but if it's similar to the Baron 58, Dan did use Art Stab for pitch only.

 

In the 64 bit update he also introduced the Torque Fix in the "avionics.lua" file.

 

While this is a nice finding, I have arrived to the conclusion that the "Torque Fix" has negative impact on engine performance figures and if an author designs an engine with certain parameters in mind and latter on applies the torquer fix, the resulting performance can differ significatively from what was initially designed.

 

Also, since today we learned that Austin is dedicated to find a better solution for the prop effects, I guess we should wait for it, and then all aircraft that presently suffer from the overdone rolling tendencies will most probably behave in a more realistic fashion.

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I agree and hope that Austin will see fit to "fix" these things, but, in the interim, I appreciate the suggestions you have made in Art Stab and all your efforts in the direction of torque control.  It has been one of the most frustrating aspects during my move to XPX.  I can however, see issues with those aircraft whose authors have worked out these problems.

 

Thanks again,

 

John

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Yes John, I also looking forward for what Austin is going to bring us :-)  Bright times ahead on X-Plane's land ;-)

 

I've been running a lot os tests with my 3 main GA sims - fsx, xp10 and elite.  I was able to finally figure out why there was one add-on for fsx that had so much "torque effect" resulting in pronnounced bank to the left at higher power settings, but also on a more or less consistent requirement for using right rudder, not common to most fsx add-ons (?) - the Aerosoft DR-400.

 

Well, after more than 1 yr with that aircraft in my hangar, I finally found out what was happening behind the scenes, and why it was so... torki :-)

 

On that model a tweak is used to overcome fsx's inexistent slipstream modelling ( just p-factor and torque ). The "plugin" that comes with the aircraft automatically adds rudder and aileron trim ( aileron trim is not even available in the real and model aircraft, but it's added "in the dark"...) to cause that yaw and roll. Since I have two joystick buttons assigned to neutralize rudder and aileron trim, hitting one of them revealled the trick :-)

 

It's triggered whenever you use some throttle settings, and indeed that DR-400 shows a lot of roll and yaw, and even consistently asks for rudder inputs during turns like described on  aprecious article Larry posted here a couple of days ago ( MANDATORY READ POSTED BY LARRY ), such as on most prop aircraft more rudder being need for left than for right turns, with "outside rudder" sometimes being required on a left turn, and left ( cross-controlled ) aileron on a right turn, to get coordinated.  This effect while present on X-Plane prop aircraft ( even if mild ) is almost absent from FSX prop aircraft, but that DR-400 had it!

 

A trick was used, just as my suggested "antoi-torque" tricks, actually not mine but rather pointed out to me long ago by Goran from LES!!!

 

I'd rather have a trickless sim :-), where we're not forced to use art stab and other strategies, like those hidden trim settings in FSX's Aerosoft DR-400 or the puffers on the XPFR Sbach 400, and I look forward for Austins modifications to the spriraling slipstream and and other factors playing their role on prop aircraft :-)

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