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jcomm

This really is the end of it....

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of my trolling against X-Plane's overdone torque effects :-(

 

I feel miserable, believe me....

 

I got that gorgeous A2A C172, where A2A is applying all of their expertise trying ( and certainly managing to... ) reproduce the flight / engine / etc... characteristics of a C172R.

 

Well, three  patches have been  released since the initial version, dealling primarily with some problems with the instruments panel and the brakes, and some not so well accepted control sensitivity ( à-la X-plane :-) ), and from patch to patch this aircraft is becoming an even better model, but, I had a problem with it since day 1... It banked a LOT, even more than the default C172 on X-Plane10.22, due to torque :-/

 

Whow! I thought to myself... Austin got a job at A2A trying to get some money for 10.30????? 

 

Well, from patch to patch, A2A has decided to build / invest on their own in-house p-factor and torque effects ( MSFS does not model slipstream ) and create an even closer to real experience. The guys do have at least one of these Cessnas, and fly it very often to measure everything you could think about, trying to bring to their FSX model the most accurate reproduction of a C172...

 

Well, I couldn't avoid PM'ing one of them with my torque bug trolling.... Received a first reply asking me to be more specific, and present factual data / arguments ( you bet I checked if I hadn't sent that PM to Austin, or if he wasn't really working chez A2A :-) ), tried to write down a better support for my arguments and, on a second PM, Scott, who flies the real thing for testing kindly replied with what dictated the end of my trolling against the "torque bug"... He told me that indeed all of the effects I was experiencing were perfectly realistic and reproduced exactly what the real thing does, used the very same arguments that many times some devs have used trying to explain to me and others that it's not a bug! namely focusing on the (lack of) attention a pilot in RL actually gives to yoke deflections to correct that bank tendency - it's spontaneous and the pilot himself is not recording those inputs carefully to determine if she/he had to use yoke /manche to counter the torque effects, and also maybe the fact that rudder asks for more "energy" and is thus more  noticeable, and  of course the fact that both the roll and the yaw are countered with rudder ( rudder trim... )

 

As you may expect, this observations caused quite an impact on this guy... I really quit saying whatever comes to my mind about this after all realistic feature of X-plane and FSX, and that only the best, most accurate models for that other smulator are capable of reproducing so accurately after all  ( we're talking about one of the most respected 3pd for FSX when it comes to flight dynamics modelling, and one that has gained it's reputation from the extraordinary work done in  the many models they produced!!!)

 

So, unless one day I find the $$$ to add engines to my pilot license, or get the chance to seat again in a Cessna, Piper, Beechcraft, whatever and be able to test it myself ( I will hire one if I win the lotery!!!!) this is the last time you will read nything crytical from me regarding the torque stuff.

 

I'm torqueless :-(

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I got myself the A2A C172 and wish I could take it and transfer it into X-Plane. Quite frustrating, as I love the scenery setup I have in X-Plane, but the planes aren't the greatest (although using the torque fix, it's much better).

 

And with the recent announcement of P3D v2 beta changes, it's looking even less likely that there will be a mass migration over to X-Plane :-). Oh well, keep wishing

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For me it was actually the opposite... That info leak brought my attention back to X-Plane 10... I have my reasons, but I will not have the time to write about why...

 

But, since you own that great A2A C172, please take the time to compare the flight model to the default, vanilla C172 in X-Plane 10, and find out how much, even the roll due to torque and how it varies with speed, the aircraft attitude in cruise, etc... are so similar between both sims ;-)

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I will to have to play and compare again this evening, I haven't used the default C172 in X-Plane for a while, but I remember it was much harder/satisfying to fly than the default in FSX. It's hard to describe, but X-Plane gives me a better feeling of flying and feels more realistic (as much as we can get realistic sitting at a desk), and the A2A C172 is one of the only planes (besides the majestic q400) in FSX that also gives me this impression. I remember someone here described it as "flying-on-rails", which is exactly how I feel with most of planes in FSX.

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I will to have to play and compare again this evening, I haven't used the default C172 in X-Plane for a while, but I remember it was much harder/satisfying to fly than the default in FSX. It's hard to describe, but X-Plane gives me a better feeling of flying and feels more realistic (as much as we can get realistic sitting at a desk), and the A2A C172 is one of the only planes (besides the majestic q400) in FSX that also gives me this impression. I remember someone here described it as "flying-on-rails", which is exactly how I feel with most of planes in FSX.

Uh oh...LAdamson's flight model klaxon just went off.  I think I hear him running down the hallway to counter your "flying on rails" comment.

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On the OP my main purpose was to enphasize how after all I came to find one of the most acclaimed GA aircraft models available for MSFS so closely matching the performance of an identical aircraft model in X-Plane 10.22

 

For one, I noticed that almost all good GA prop aircraft models developed for FSX, those I own, from A2A, RealAir, Aerosoft, and the default aircraft in FSX Golden Edition, all exhibit roll due to torque, sometimes very pronnounced, like the example I gave of the recently released A2A C172.

 

Being a notable player in the World of FSX add-ons, and given that the A2A Team owns a couple of aircraft and uses them to obtain all of the test data used to fine tune their models, and because I was told so by their "test pilot", I have to accept that, after all, the rolling moment created by torque during a wide range of flight situations ( power, speed and AoA ) is very noticeable and requires either right rudder or, a mix of yoke and rudder to counter.

 

The turn coordinator "ball" physics are better, even if not perfect, in X-plane 10 than in FSX and the poor performance of that instrument in FSX has made A2A start internal developement of their own turn coordinator instrument, which will become available in a future patch or core update for all of the A2A models.

 

A2A also acknowledged the poor modelling of p-factor ad torque in the core FSX flight dynamics engine, and are working on their own implementation, bypassing FSX's calculations and using AccuSim to bring a much more realistic experience to their users.

 

From all of the above I am forced to accept that, after all, X-Plane's flight dynamics model is superior to that of MSFS, because it can be tunned, through the use of RL techniques like trim tabs, asymmetric lift, canted engines or canted tail surfaces, to perform the right way and counter those effects at least at cruise settings.

 

Of course I still believe that LR should dedicate a bit of their time to bring the prop effects even closer to reality, within the limitations of such a type of PC-based simulator, but what I have to accept is that my claims of incorrect / inconsistent behaviour of prop aircraft due to torque effects are most probaly not valid, and result from the fact that, after all, I am not a prop aircraft pilot in RL!!!

 

Regarding yesterdays unexpected leak of information regarding the upcoming LM P3D v2, and as far as I am concerned, the most important aspect for me of a flight simulator - flight and overall physics modelling - was the most remarkable exception fom the long list of certainly very interesting features.

 

Talking to other simmers it was obvious that the list brought great expectations in as far as rendering quality and making use of modern hardware go, and this by itself can probably help overcoming the limitations imposed by v2 being still a 32 bit app, and it's great that we simmers can get exactly what fulfills our expectations, but for me, it didn't really bring any info that can make me think that LM P3D v2 is the way. Add to it the fact that probably we will still not be able to see great add-ons, like those produced by PMDG, available for that platform, and I really don't feel attracted to it...

 

To be honest I feel more and more attracted by platforms such as DCS World, and the upcoming IL2 Sturmovik Battle of Stalingrad, where I can see a good deal of investment in the accuracy of their flight models, and actually, just as Murmur also pointed out in another thread, it's possible to find similar approaches to that followed in X-Plane 10 ( the BET ) being used. Those simulators make use of very detailled and precise data for each modelled aircraft, including many RL aerodynamic tests run during the 2nd WW, or on modern fighter aircraft and helicopters, to bring their models to the level of accuracy we DCS users are so fond of.

 

Maybe if an aircraft for X-Plane 10 can be designed with such precious info, and tunned using plane-maker to overcome the necessary limitations of X-Plane's flight model ( all pc-based sim will certainly have it's own limitations... ), it will exhibit the same quality and accuracy of those models I love to use in DCS and look forward to use in IL2 Sturmovik when released...

 

Problem for me is that such a simulator ( DCS or IL2 )  is far fom fulfilling my needs and wants as a simmer, because I do not like the military side of aviation, and using 80% of the available features on those platforms is something I am not really interested in, so, I will always need a Civil flight simulator for complement... 

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Uh oh...LAdamson's flight model klaxon just went off.  I think I hear him running down the hallway to counter your "flying on rails" comment.

 

:LMAO:  :LMAO:  :LMAO:  :LMAO:

 

Exactly what I was thinking!

 

 

but what I have to accept is that my claims of incorrect / inconsistent behaviour of prop aircraft due to torque effects are most probaly not valid, and result from the fact that, after all, I am not a prop aircraft pilot in RL!!!

 

I admire you honesty jcomm.

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So-----

 

How is the rigging in these Cessna "test planes"? Remember the link I sent, for the company that re-rigs older Cessnas to get rid of unwanted use of trims, which causes drag?

 

 

My RV, being much smaller than a Cessna, but with the same 180 HP engine that the 172SP uses, had much more pronounced torque pressure on the takeoff, than the 172 ever does. Yet, you would notice it's effect much more, if it was a touch and go, instead of a normal roll down the runway.

 

 

At the same time, I have many photos of the climbout, and the ailerons are not deflected to account for a roll. I happen to know that the RV was rigged very well.....as I went to a lot of precise measuring to make it so.

 

 

We know that the effect of lift is a square of airspeed. We know that a lot of planes use an offset engine thrust to counter yaw effects. Some say that it also moves more air over the inboard section of the left wing, to also counter roll. Keep in mind, that rudder will effect any plane with diheadral (spell?) in it's wing, as it will want to roll. I can't say what the exact effect of a Cessna, with it's fuse hanging under the wing. Any time that yaw is present, if it's not being countered by an offset vertical stab, fixed, or adjustable rudder trim..........then roll can take place, because of the plane's diheadral, which is built in for positive stability. This is the method that all of these cheaper R/C planes use. They use just rudder for turns, as the wings have no ailerons.

 

 

If these simulated planes have a constant roll effect, that can't be countered with rudder, then they need a virtual re-rig job. Pilots are not going to sit there all day, and hold the yoke against a roll force, because the plane has no aileron trim.......which Cessna 172's do not.

 

 

 

name="GoranM" post="2807231" timestamp="1380013748"]

Uh oh...LAdamson's flight model klaxon just went off.  I think I hear him running down the hallway to counter your "flying on rails" comment.

 

I had to sign myself back in. Pushed a wrong button on the CPU the other day, which seemed to dispense with all my passwords. In the meantime, I must go out of state for today. No time to discuss flying on rails

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Of course I still believe that LR should dedicate a bit of their time to bring the prop effects even closer to reality, within the limitations of such a type of PC-based simulator

 

Probably the helical propwash effect is significantly underdone in X-Plane. MortenM (developer of the Piper Archer for X-P) once said the real aircraft engine has 3 degrees cant to the right, but the real a/c still tries to pull left on takeoff roll.

 

In X-Plane instead, very little right cant (around 0.5 degrees, I think) is enough for the aircraft to pull right on takeoff (and in flight).

 

This seems to be consistent with the fact that power variations have less effect on yaw in X-Plane compared to real life.

 

What would be needed is a customizable parameter similar to the "acf_prop_dir" tweak, but influencing _only_ the helical propwash effect.

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What would be needed is a customizable parameter similar to the "acf_prop_dir" tweak, but influencing _only_ the helical propwash effect.

 

Yes, like the p-factor_on_yaw, torque_on_roll and high_aoa_on_yaw we have in FSX :-)

 

The propwash effect is probably not the problem, but rather some tuning still required on the asymmtric slipstream/ propwash, but for the time being, I'll use the trim, and set trim tabs again on most prop aircraft.

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At the same time, I have many photos of the climbout, and the ailerons are not deflected to account for a roll. I happen to know that the RV was rigged very well.....as I went to a lot of precise measuring to make it so.

 

Do your remember how many degrees is your RV engine canted? Also, apart from the engine cant, did you had to make other asymmetrical rigging on surfaces etc?

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Here's a first flight video I found on a C172 of a 10 year old. I don't see any compensation on the yoke from the pilot to counter a torque roll on takeoff here and the plane is tracking straight. I'm sure he's using rudder to compensate for P-Factor but I don't see a torque roll issue.

 

www.youtube.com/watch?v=chcQrIog8HY

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We know that the effect of lift is a square of airspeed. We know that a lot of planes use an offset engine thrust to counter yaw effects. Some say that it also moves more air over the inboard section of the left wing, to also counter roll. Keep in mind, that rudder will effect any plane with diheadral (spell?) in it's wing, as it will want to roll. I can't say what the exact effect of a Cessna, with it's fuse hanging under the wing. Any time that yaw is present, if it's not being countered by an offset vertical stab, fixed, or adjustable rudder trim..........then roll can take place, because of the plane's diheadral, which is built in for positive stability. This is the method that all of these cheaper R/C planes use. They use just rudder for turns, as the wings have no ailerons.

 

All very good observation Larry.

 

I have been thinking so much about all this that my neurons are kind of fried.

 

A couple of months ago I had a similar exchange of oppinion with the guy fromAerosoft who did their DR-400, and he confirmed a lot of roll and not only yaw as a result of prop effects on the aircraft he used as a RW model.

 

Before I get my hands in a real Cessna, Piper, Beechcarft, which is a real problem for me because it is going to be expensive, I will not - again - oppose those who say it's right the way it is modeled in X-Plane and in FSX too, at least on some models, or if it is wrong...

 

In X-Plane I always make sure the Artificial Stability Sliders are Fully LEFT - no Art Stab - on all of my tests.

 

I have experimented with the C172, and a few other aircraft, simply by setting the trim tabs, and I get straight and level at cruise. The A2A C172 will also fly straight & level in cruise at higher speeds, well inside the yellow arc. Bellow that, even at level flight, roll to the left will be present!

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Later today, I'll try to bring that A2A C172 and the XP10.22 C172 into similar performance torque-roll wise, by setting aileron trim, as if it was a trim tab, on both. Then I will go to plane-maker and adjust. In FSX I can't do the same unless I program it using XML or C++, something I really don't want to invest in ...

 

The A2A C172 is also reproducing that "reverse torque" as someone from their team called it, when you reduce power and the aircraft tends to roll and yaw to the right. On low power descents it is quite evident, and something we have long been able to find on prop aircraft in X-plane 10 too.

 

Meanwhile I am buying the lotery once a week. Should I become rich, I'll spend a few hours renting Cessnas, Robins, Rallyes, Pipers, Beechcrafts... to join their pilots in the right seat and do all of the testing I am allowed to :-)

 

A flight on a p51 would be great as well.

 

It also possible to get a Pitts or Extra flight around here!!!

 

Imagination is something I really to not lack...

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Thank you for this post Jcomm ... I've been feeling let down by X-Plane 10 for the past month or so, but reading your post has started to make me feel much better about my investment in XP10. For me the issue of which simulator has the superior FDM has now been put to rest.  FSX maybe nicer to look at but X-Plane has the more accurate flight model.

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I'm very happy too :-)

 

And really looking fwd for the 10.30 announcement, and whatever  follows it :-)

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I personally never did mind the "torque bug", and although I don't have any real experience as a pilot, the BUG did made my flight experience feel different and even more challenging than FSX. With my brother being a pilot, I've had quite a few hours as a co-pilot and XP10 is what really feels closest to the real thing.

This my own perception of virtual flight vs real, so your mileage may vary.

 

Anyway, welcome back guys, the future does look bright whether XP10 or P3D v2 or both.

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It depends

 

It certainly does Andras. Beautiful shots!  Thanks for sharing!!!!

 

Curiously today I was thinking about how the updated World mesh & scenery will be made available, since it's going to be a few Gigas worth the download ?

 

Will it be hosted at LR's site?

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I'm very happy too :-)

 

And really looking fwd for the 10.30 announcement, and whatever  follows it :-)

the cloud addon releasing soon will make me an xp10 full-timer.  XP10 really needed moving clouds.

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It certainly does Andras. Beautiful shots!  Thanks for sharing!!!!

 

Curiously today I was thinking about how the updated World mesh & scenery will be made available, since it's going to be a few Gigas worth the download ?

 

Will it be hosted at LR's site?

Nope ... via flightsim.com (they offered me "what ever I want" and all help I need ... and yes, we are talking at least about 60-70 GBytes).

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alpilotx, on 25 Sept 2013 - 08:17 AM, said:

Nope ... via flightsim.com (they offered me "what ever I want" and all help I need ... and yes, we are talking at least about 60-70 GBytes).

Great!

 

Andras, A BIG THANK YOU for all of the hard work you have been taking for the benefit of the whole X-Plane 10 user community.

 

I really would expect Laminar Research to support it too, after all, it's an important argument in favor of X-Plane for most users, given the times and the news...

 

To my OP I would like to add that I also think that this is really the right moment to see something like "News" from LR. They will have a very small time window IMO to prove to users that X-Plane 10 is really worth the investment.

 

We X-Plane 10 users have good reasons to still believe that this simulator has a future. Efforts like those by you Andras, PilotBalu, those who are contributing through OSM like some of our forum members, other sites that help promoting / supporting X-plane, 3pds creating wonderful add-ons, make a lot for our and others minds, but now there should really be a sign of the good things to come from the LR team.

 

The news regarding LMOC's upcoming P3D v2 really made me invest again in x-plane. I believe my PMDG stuff will most certainly not run on it, so I would be forced to keep FSX if I want to use it. OTOH, we know PMDG will, sooner or later, embrace X-Plane 10 and announce their first product. Could it be a modern Boeing airliner ?

 

The new simulator will probably not bring an updated flight dynamics model, as far as I was able to get from the leaked info. X-Plane's flight dynamics model is in a continuous process of upgrade ( so I hope... ), so, even those things we do not still like have a chance of getting fixed.

 

Then, there is that 64 bit argument. It's not really that important for me, but the truth is that my other sim, DCS, has also migrated to a 64-bit only platform, and that appears to be the tendency for any future flight simulation products. Being already there, X-Plane 10 clearly has an advantage on this too.

 

Let's hope that the announcement of 10.30 reveals something good about the future of our "X" sim, even if meant only to become available on a future beta!

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Great!

 

Thank you for all of the hard work you have been taking for the benefit of the whole user community.

 

I really would expect Laminar Research to support it too, after all, it's a keeper for most users, given the times and the news...

They support it in other ways. As I am freelancing for them since years, and this work is usually a spin-off from that work ... or that work is a spin-off from this work ... it goes in both ways :wink:. All of my scenery stuff is not disconnected from what happens inside Laminar (it wouldn't even be possible without the inside stuff, source code hacking, fixes, artwork additions, discussions etc.).

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The A2A C172 is also reproducing that "reverse torque" as someone from their team called it, when you reduce power and the aircraft tends to roll and yaw to the right. On low power descents it is quite evident, and something we have long been able to find on prop aircraft in X-plane 10 too.
I call that fairy-tail flight dynamics. Why would the airplane want to roll to the right on descent with power pulled back, unless you purposely have an asymmetric setup with fixed tabs or wings with different incidences? It's one of the reasons that building an airplane with different incidences has gone out of style, a long time ago. There will be right yaw, as long as you have a fixed rudder tab, or vertical stabilizer with a built in offset. These are built into the plane, to prevent a continuous yaw in cruise. Otherwise, your right foot is on the rudder the whole time, and rudder forces can be high. Let the plane yaw, and some roll will come into play. Then, if you let go of the yoke, you'll visually see some roll. In real life, the force wouldn't hardly be noticeable, if at all. For computer flight purposes (especially with non-pilots), this visual roll could be interpreted as a powerful force, such as pitch and yaw. To answer another question. My plane had a three degree cant, as I remember. Could have been 2 1/2. The wings are perfectly straight with each other. Done with smart levels, plumbobs, strings, and chalk lines. Nothing to designed to cause an opposite roll motion to torque. Fixed tab on the rudder, to keep the ball centered in cruise.And one more. When a Cessna 172 is built, it's taken on a test flight. It has adjustable cam bolts on the rear wing spars for both sides. Any roll tendencies for either left of right, can be adjusted out. This would be done for cruise speeds, and certainly below the yellow arc.I've mentioned it before, but will do so again. My RV initially wanted to roll to the right, if I let go of the stick. Even full aileron trim, couldn't keep it level. On the other hand, the force, was minimul. I didn't even notice on the first test flight of three runs around the pattern. I just never let go of the stick. It's what we call a heavy wing. It's not trying to roll the airplane around and around. Of course, the roll to the right, is opposite of the typical so called torque roll to the left. What it was, is that the left aileron trailing edge, had slightly more radius than the right. Less than 1/16". With a light squeeze for about three feet, the radious was reduced. It didn't even chip the paint. Now, the trailing edges of the ailerons will trail perfectly with the wing tips & flaps. They were all perfectly aligned to start with. And that's with the trim tab at neutral or close too. It's only used to offset passenger, or fuel weight. I like the feel of hands off the stick, with no pressures at all. It's why I installed an aileron trim. Cessna 172s don't have them. Still won't hold altitude and heading like an auto-pilot. It will eventually drift.....just like FSX or X-Plane. It's not on rails.

 

I personally never did mind the "torque bug", and although I don't have any real experience as a pilot, the BUG did made my flight experience feel different and even more challenging than FSX.
Just as a real Jetstream pilot mentioned, "this challange is irrating"....or something close to that.A pilot/ developer for FSX says the same thing, and so do I. These planes should have more positive stability, and not be a challange just to maintain a normal flight. Note: when the FSX version of the Q400 was released, it also had a tendency to torque roll to the left. It's a cause of complaints, which the pilot/developer for FSX also pointed out.

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I call that fairy-tail flight dynamics. Why would the airplane want to roll to the right on descent with power pulled back, unless you purposely have an asymmetric setup with fixed tabs or wings with different incidences?

 

One of the reasons is exactly that one: if the aircraft is built with the fin canted, or has aileron trim tabs set for cruise to counter roll, or rudder tabs to counter yaw, on a high speed ( safe ) descent you will start to see a yaw / roll to the right.

 

The other reason is that under such circumstances, and specially on CS props where the pitch is automatically adjusted to fine, it's the airflow that drives the prop, and actually applies a force on it trying to make it turn faster ( and it starts turning faster easily on aircraft fitted with fixed pitch props ). This force is exerted on the engine crank and, just like with torque, there is a reaction ( ooposite ) this turn around from the engine, in the opposite direction. This is naturally transmited to the aircraft and can result in an additional tendency for the right rolling moment.

 

Add to it the very faint effects of the spiraling slipstream, with very "few energy" it now has, and thus not able to act over aircaft surfaces as it did at full power and high AoA / low speed, and there will be nothing to counter that right rolling ( and yawing ) tendency.

 

The bigger the prop, the bigger the effect, and on the P51d ( in DCS ) it is documented and very noticeable ( and even more because that aircraft had a considerable fin cant )

 

BTW, Larry, the cant you mentioned on your RV6 was fin or engine cant?  Were they both canted? Was the aileron trim tab on the right wing, or it only had a rudder trim tab?

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