What tweak to stop heavy turning tendency in all props?

[Murmur 3,940]

Also, since in X-plane ( just like in MSFS ) setting trim on a mechanical control surface will not make it move when the airflow starts building over it, you will also see no movement starting to happen on the controls in the cockpit :-/

 

P.S.: On what I still consider the best flight dynamics model ever built for a flight simulator, DCS World and for instance it's P51d, correctly shows the effects of seting trim as soon as speed builds up. Even stopped on the floor, if you add significative winds from 12 o'clock, you'll be able to see the control surface starting to move because of the force exerted on it by the trim tab :-)

 

The  ":-/" emoticon is misplaced. There is not a right (DCS) vs wrong (X-Plane/FSX) modeling of trim behaviour in a pc flight simulator.

 

What we have here is a fundamental limitation, namely the fact that usually a PC flight sim has to be designed for sticks/yokes not capable of force-feedback, nor self-motion. For this reason, the approach used to model trim behaviour in a flight simulator is not univocal.

 

Most flight sims (FSX, X-Plane, etc.) model a "stick fixed" behaviour: the controls will not move unless the user moves the joystick, and the equilibrium position of flight controls is solely determined by trim position, unregardless of the airspeed / AoA.

 

Now, if you think about it, the DCS behaviour is actually not 100% coherent: it considers the effect of airflow on the trim surface, but does not consider the effect of airflow on the complete flight control surface. What I mean is, if the modeling of DCS were 100% coherent, the whole flight surface of e.g. the elevator, would deflect and tend to remain a little deflected in case of a sudden increase in AoA, tending to align with the airflow (this would model the so called "stick free" behaviour).

 

The DCS behaviour, with the trimmed elevator deflecting under the effect of airflow, is, from a practical point of view, not much more than a cosmetic effect. From my experiments, the actual behaviour of flight controls in flight is, in both cases (FSX/X-Plane vs DCS) the "stick fixed" behaviour, that is, the flight surfaces does not react to airflow. Personally, I prefer the FSX/X-Plane approach, that is 100% coherent and where there is a univocal relationship between joystick position and flight controls position.

 

The fact that DCS has more refined flight model is another story and not linked to this trim issue...

 

Marco

[pryoski 84]

Well .. I used to be a firm believer in the "Torque is modeled correctly" school of thought, but now I'm not so sure .. in fact now I'm trending the other way, with the caveat that (as jcomm's pointed out elsewhere) it's not necessarily torque itself that's modelled incorrectly, but some other limitation in the FM that sets up the torque modelling to have an exaggerated effect on the aircraft's handling.

As I don't have a scientific perspective (not even basic maths and physics .. ), I rely a lot on those boffins who do in order to form my opinions, and also on people with real world perspectives to draw upon. It's not real understanding .. it's more of a faith thing lol!

I'm hopeful that this issue will be addressed sooner, because like JComm has said .. this is a flight simulator, and like JComm I sometimes experience an existential meltdown when I consider that the sim I'm flying is a inadequate representation of reality. So .. @ the moment I have 4 sims on my PC ... X-Plane, FSX, P3D and DCS ... and I drift between each as my dissatisfaction with any one set of issues becomes too great to bear.

P.S.

I have completed the following fixes .. and they work to my satisfaction ..

1. JS32 - CW/CCW fix
2. AN-24 - I think was already CW/CWW on my release ..
3. the default C90B - the Torque fix applied to both engines work like a charm .. so does the CW/CCW fix (obviously not both at the same time!)

4. FJSim Dash 8 - CW/CCW

 

** The MU-2 - doesn't matter which tweak I use .. this plane behaves erratically so I'll keep flying it the way I used to .. but my new perspective has spoiled the experience for me!

.. and then for a break I also fly a lot in my brand new Flight1 KingAir B200! Now REALLY I wish they would do some of their magic in X-Plane .. once the torque stuff is sorted .. or design it specifically to behave as it should. Cheers, Kris P.

 

P.S.. We should ask en masse @ Frooglesim's Youtube channel for him to push the question to Austin and Ben .. hopefully he has more traction?

[LAdamson 240]

As I don't have a scientific perspective (not even basic maths and physics .. ), I rely a lot on those boffins who do in order to form my opinions, and also on people with real world perspectives to draw upon. It's not real understanding .. it's more of a faith thing lol!

 

 

I put out my thoughts, because I never observed it, in RW flight...........except for the situations as already mentioned; slow airspeed and high power, or pushing the left gear down on the takeoff roll, during a touch and go. And since there are many aircraft I haven't flown in real life, I started asking other pilots, as well as digging up a lot of pilot reports on the internet, in addition to many videos. I've found nothing to imply, that there is a continual force, which needs to be trimmed out, as a normal phase of flight. As airspeed doubles, lift squares. That means that the force of lift is easily overcoming the torque produced by the engine and prop.

 

When I was finally able to ask a friend about his piloting experience with the 2800 HP single engine Skyraider.........and he said that it was "yaw" to worry about on the takeoff roll, and not roll.....my level of being convinced, increased by a larger margin. The Skyraider is included in a group of planes, that could easily roll sideways off the deck of a aircraft carrier, if the pilot punched the throttle after missing the wire. Once again, that's a case of high power combined with low airspeed. In the normal course of takeoff, enough lift is provided to overcome the roll tendencies, once the plane has enough speed to sustain a normal takeoff. Lift is quickly multiplying from that point onward.

 

As to the MU2. I have not talked to a rated MU2 pilot. I've only read articles on the internet and in magazines.

[pryoski 84]

Thanks LA .. you were actually the catalyst for my developing perspective .. way back when .. and I believe we all got a little hot under the collar .. I owe you an apology! Friends?
 

 

[jcomm 5,882]

@Murmur: 

"but does not consider the effect of airflow on the complete flight control surface. " - not true :-) - observe what happens to your other control surfaces as you deflect your rudder wildly... 

 

@pryoski:

 

Just like you I also have a few sims: FSX, DCS, ELITE, X-Plane.

 

My only grip with DCS is that the concept/purpose of that sim is far from what I really like in a sim. I use it solely to be able to profit from what I consider the most advanced flight dynamics model available for a PC sim. There are limitations in that sim though, such as poor modelling of navaids ( can't do a nice IFR flight unless I pick the fancy A10c, ka50 and program their FMSs...).

 

In ELITE I have a rather old-fashioned ( fs4/fs5-like ) world representation, but a tremendously accurate engine and in some aspects also light dynamics model, provided you fly your aircraft inside of the regular IFR envelope. In terms of instruments, and easy reading of them all in the 2D instrument panel, ELITE is also superb! and a great tool to practise IFR, allowing for RWW injection as well...

 

X-Plane 10 is, for me, put on hold again. I'm really becoming tired of some limitations / innacuracies ( some very basic ) in it's flight dynamics / systems / engines modelling and even in terms of how it renders the World around you, models navaids, etc... It has potential, but as far as I am concerned, it is frozen, waiting for Austin to melt it...

 

I gave up on P3D simply because I wanted to have FSX to be able to use aircraft that are not available for the Lockheed platform. Having both would be... a mess for me... FSX is, after all these years and since I started using it, then quited using any sim around 2007, and came back with MS FLIGHT, after all - I'm going to be fulminated by writing this, but I couldn't be more honest... - the most advanced, embracing, complete, civil flight simulator still available ( yes, I have an eye on each new Flight Gear release, I still remember Fly! and Propilot, Flight Unlimited, MS FLIGHT, and a couple of others less known to the public...).

 

So... I would classify mostly as a VERY SATISFIED FSX user, a DCS lover, an ELITE loyal admirer, an X-Plane 10 "hoper" (the word does not exist in english, I believe...)

 

Guys... don't measure flightsims by the number of bits in the address space.... Classify them by how their vehicles behave on the simulated air / space / World as a whole... how accurate, detailled, overwhelming some add-ons can be, the number of available choices of add-ons of quality to suit your needs, and of course their intrinsic potential... 

[pryoski 84]

 

 

Classify them by how their vehicles behave on the simulated air / space / World as a whole...

 

But ..? You've already mentioned that FSX doesn't do multi with engine failure ... even the mighty PMDG 777!

 

I do recognise what you're saying though. I too experience a flight simming induced existentialist melt-down on occasion! :lol:

[jcomm 5,882]

Yes, of course FSX has lot's of limitations when we get outside of the "normal" flight envelope (and so does X-Plane 10 ) and has poor engine out effects ( that can be fine tuned and are nonetheless very acceptable on some aircraft ). 

 

:-)

[jcomm 5,882]

 

 

** The MU-2 - doesn't matter which tweak I use .. this plane behaves erratically so I'll keep flying it the way I used to .. but my new perspective has spoiled the experience for me!

 

In the MU-2 the editing through P-Maker, choosing a combination of CW and CCW also works. Just make sure that when you select the aircraft for flying, and while standing on the rw, you reset the aileron trim to neutral ( I have a joystick button programmed for aileron and rudder trim rest to neutral ), because Tom automatically added flaps and aileron trim for takeoff, to counter the excessive roll due to torque.

[jcomm 5,882]

@Murmur:

 

"but does not consider the effect of airflow on the complete flight control surface. " - not true :-) - observe what happens to your other control surfaces as you deflect your rudder wildly...

 

Correction!   Murmur is RIGHT !!!  :blush:

[pryoski 84]

Regarding the MU-2 .. thanks anyway JComm and Ralf ... unfortunately it appears to be the only plane I have that refuses to cooperate. Your tips did work JComm, to a point. Once I'm climbing or cruiing there is still a small tendency to roll to the left ... but it is a continuous inexorable movement that eventually has me spiralling down to the left if I leave it uncorrected. In other words I'm still unable to fly 'hands off' even after the tweaks! The JS32 and the AN-24 are NOW a dream to fly though! (post tweak)

[MSFS Ralf 149]

Regarding the MU-2 .. thanks anyway JComm and Ralf ... unfortunately it appears to be the only plane I have that refuses to cooperate. Your tips did work JComm, to a point. Once I'm climbing or cruiing there is still a small tendency to roll to the left ... but it is a continuous inexorable movement that eventually has me spiralling down to the left if I leave it uncorrected. In other words I'm still unable to fly 'hands off' even after the tweaks!

 

The JS32 and the AN-24 are NOW a dream to fly though! (post tweak)

I'm sorry to hear that. Since the Mu2 was updated I never pulled it out of the hangar. The Planemaker edit worked well with the older version.

In future I will stay away from "torqued" props anyway. If the Mu would fly like the XP Mu does, I doubt that it would have a certification.

I'm not a pilot. From my time in the right seat of many GA planes and using my common sense I think the effect is x-times overdone.

[LAdamson 240]

Thanks LA .. you were actually the catalyst for my developing perspective .. way back when .. and I believe we all got a little hot under the collar .. I owe you an apology! Friends?

 

Okay...