Simicro

Is adverse yaw well modeled in P3D?

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Hi,

After years of carelessness, I decided to re-learn the basics of flying and yesterday I read the chapter "rudder" in Stick and Rudder by Wolfgang Langewiesche.

Now I better understand what is adverse yaw and the necessity to use rudder in turns.

At this time I'm flying the A2A C172: in a 30 degrees turn, the ball is perfectly centered while I apply NO rudder at all?!?! Normally the ball should be more on the right side indicating that action on rudders is required?

I confess that I did not pay too much attention to adverse yaw when I was on FSX or other simulators but I don't recall noticeable adverse yaw whereas in real life I read that instructors insist a lot on the use of rudders to make coordinated turns.

Hence my question: is adverse yaw is well modeled in P3D (and other simulators)?

Maybe in recent/modern GA aircrafts, the design is better and adverse yaw limited?

adverse_yaw.png

Edited by Simicro

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Ensure your autorudder option is disabled.

The basics of adverse yaw depend as much on the flight model as the simulator platform.  If you want realism get ahold of the quality stuff from A2A.  They have very good flight dynamics for a PC simulator.

Nothing replaces the seat of the pants that you get in the real thing.

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Don't forget that 172's etc have differential ailerons that offset any adverse yaw. Most modern aircraft aren't affected significantly compared to older types such as Austers etc.

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11 minutes ago, downscc said:

Ensure your autorudder option is disabled.

.  If you want realism get ahold of the quality stuff from A2A.  They have very good flight dynamics for a PC simulator.

 

That’s exactly what he’s flying. So maybe the auto rudder is on as you say. 

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1 minute ago, DavidP said:

Don't forget that 172's etc have differential ailerons that offset any adverse yaw. Most modern aircraft aren't affected significantly compared to older types such as Austers etc.

 

True. I did some learning to fly many years ago. I never used the rudder because I was never told to use them. 

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Very little rudder is used in the real 172 on level flight. 

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1 hour ago, Simicro said:

At this time I'm flying the A2A C172: in a 30 degrees turn, the ball is perfectly centered while I apply NO rudder at all?!?!

I haven't flown the A2A 172 since I moved over to P3D from FSX but my recollection of it was that rudder was absolutely needed when appropriate.  In fact, my early criticism (before some of the first patches) was that it required too much.

As others have suggested, make sure autorudder is turned off.

5 minutes ago, Raging Bull said:

True. I did some learning to fly many years ago. I never used the rudder because I was never told to use them.

Wow.  I'm going to guess that you never went much past a simple introductory flight lesson.  Especially in the pattern, my primary instructor would all but reach over and slap me if I didn't keep the ball centered.  Almost all maneuvers to be mastered for a PP certification require rudder attention, as do normal takeoffs and landings - especially in crosswind situations. 

Sure in normal level flight you can keep your feet on floor for minor turns and course corrections without making your passengers barf, but for other phases of flight and for practice work on basic skils (turns around a point, steep turns, stalls...), you need to learn good rudder work.  Fly a tail-dragger and you REALLY need to learn those pedals.

There are a few planes which feature rudder-aileron interconnects which help keep the ball centered (A2A models one of these with their new Bonanza) but even with these you need to use the rudder for all but normal turns.

Scott

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1 minute ago, Bobsk8 said:

Very little rudder is used in the real 172 on level flight.

The OP referenced a 30 degree turn.

Scott

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10 minutes ago, tttocs said:

Sure in normal level flight you can keep your feet on floor for minor turns and course corrections without making your passengers barf, but for other phases of flight and for practice work on basic skils (turns around a point, steep turns, stalls...), you need to learn good rudder work.

I think you'll find in types such as the 172 that most of the rudder is to do with engine torque. Demonstrating adverse yaw in these types, while not difficult, meant aggressively rolling the aircraft left and right and eventually you could see some sort of effect. The amount of rudder input needed on these types is often overstated by simmers.

 

Tail draggers, of course, are different beasts.

Edited by DavidP

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17 minutes ago, tttocs said:

I haven't flown the A2A 172 since I moved over to P3D from FSX but my recollection of it was that rudder was absolutely needed when appropriate.  In fact, my early criticism (before some of the first patches) was that it required too much.

As others have suggested, make sure autorudder is turned off.

Wow.  I'm going to guess that you never went much past a simple introductory flight lesson.  Especially in the pattern, my primary instructor would all but reach over and slap me if I didn't keep the ball centered.  Almost all maneuvers to be mastered for a PP certification require rudder attention, as do normal takeoffs and landings - especially in crosswind situations. 

Sure in normal level flight you can keep your feet on floor for minor turns and course corrections without making your passengers barf, but for other phases of flight and for practice work on basic skils (turns around a point, steep turns, stalls...), you need to learn good rudder work.  Fly a tail-dragger and you REALLY need to learn those pedals.

There are a few planes which feature rudder-aileron interconnects which help keep the ball centered (A2A models one of these with their new Bonanza) but even with these you need to use the rudder for all but normal turns.

Scott

 

I flew many more flights then an ‘introductory’ flight including solo many times. And using rudder was never really taught as a requirement except landing in a crosswind. 

 

As some have mentioned, it’s not really as necessary as many think. 

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20 minutes ago, Raging Bull said:

 

I flew many more flights then an ‘introductory’ flight including solo many times. And using rudder was never really taught as a requirement except landing in a crosswind. 

 

As some have mentioned, it’s not really as necessary as many think. 

Trust me, it's very necessary.

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32 minutes ago, DavidP said:

I think you'll find in types such as the 172 that most of the rudder is to do with engine torque. Demonstrating adverse yaw in these types, while not difficult, meant aggressively rolling the aircraft left and right and eventually you could see some sort of effect.

I have a few hundred hours grinding through the sky in a variety of 172s.  If you're suggesting that the ball will stay centered in a 30 degree banked turn without rudder input, I guess we'll have to agree to disagree.

That said, as I noted, one of my initial complaints about the A2A 172 as it was originally released was that the need for rudder use was greatly exaggerated.

23 minutes ago, Raging Bull said:

I flew many more flights then an ‘introductory’ flight including solo many times. And using rudder was never really taught as a requirement except landing in a crosswind.

My apologies if my comment came off as overly dismissive - not my intent - but I was certainly drilled from hour one on rudder use in everyday stuff like takeoffs and pattern work, without even getting into stuff like stalls (which I'm sure you worked before soloing), slips and all of the other PP maneuvers.

Scott

Edited by tttocs

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I find that in the A2A 172 is well modeled. Not only will you need right ruder (right turn) to maintain coordinated flight at a 30 bank, but you also need to hold some back pressure to maintain altitude, and sometimes you might need opposite aileron to prevent the over banking tendency as a result of the outer wing traveling faster and creating more lift than the inner wing.

Edited by DJJose

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8 minutes ago, DJJose said:

Trust me, it's very necessary.

 

Well, having flown some real aircraft around the skies never using or ‘needing’ rudder, it’s wasn’t necessary. (C152 i recall and a Piper warrior on occasions). 

Perhaps it wasn’t totally ‘coordinated’ in the turn, but barely (or not) noticeable anyway. I never looked to be honest at the turn and slip indicator. Most light aircraft turns are not that sharp so never really need it.  

I’m guessing if multiple intructors never taught me to use it wasn’t necessary. 

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At a very basic level:

My early flying was gliders (got to Silver 'C' standard, probably preferred gliding to powered tbh). The use of rudder in a turn is way more in gliders than it is in powered. There is also a lot of 'jockeying' of the rudder in a turn to keep the reference point balanced on the horizon / fight against a thermal pushing you out etc. so when I moved over to powered I found initially I was over-controlling the rudder.

Adverse aileron yaw is caused in the main by deflection of the ailerons (no surprises there!) and the effect that has on the shape of the wing / airflow over said wing. If you are in a balanced turn of any angle, once you have centred the stick you are just flying through the air so will also pretty much centre the rudder because the removal of the aileron deflection removes the requirement for rudder. There are still aerodynamic reasons for the use of rudder whilst in a banked turn, but the actual adverse aileron yaw is removed the instant the stick is returned to centre in a lateral sense. All this is based on a straight wing, of course. It was a bugbear of mine before I got into development as most FS aircraft required a progressive application of rudder purely dependant on angle of bank, whereas I have never flown anything in real life which requires such excessive use.

To answer specifically the question asked, in all FSX versions and P3D up to and including v3 the aerodynamics of this are dealt with in table 1101 (primary aerodynamics). P3Dv4, there are new tables in the .air file which address the bulk of what used to be in 1101. Both methods have the ability to create yaw moment due to aileron deflection and yaw moment due to roll rate. It is entirely dependant upon how the fde modeller chooses to interpret the subject and create it within those tables.

Paul.

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17 minutes ago, Raging Bull said:

 

Well, having flown some real aircraft around the skies never using or ‘needing’ rudder, it’s wasn’t necessary. (C152 i recall and a Piper warrior on occasions). 

Perhaps it wasn’t totally ‘coordinated’ in the turn, but barely (or not) noticeable anyway. I never looked to be honest at the turn and slip indicator. Most light aircraft turns are not that sharp so never really need it.  

I’m guessing if multiple intructors never taught me to use it wasn’t necessary. 

Just because you did not use it, did not notice it, or were not taught by multiple instructors, it doesn't mean it's not necessary.

The rudder is there for a reason and it's to correct for adverse yaw.

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9 minutes ago, DJJose said:

Just because you did not use it, did not notice it, or were not taught by multiple instructors, it doesn't mean it's not necessary.

The rudder is there for a reason and it's to correct for adverse yaw.

If there IS a lot (or any) adverse yaw. Not always a lot in some airplanes. 

I managed to land it, so that’s the main thing. 🙂

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3 hours ago, tttocs said:

The OP referenced a 30 degree turn.

Scott

I have 100's of hours in a 172, and a 30 degree level turn requires almost no if any rudder. 

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As some others have pointed out, a lot depends on the actual aeroplane you fly in the sim, and by that I mean two things, first, the type and how its wings are configured, and second, who the simulation of it has been made by, because all sim aeroplanes are certainly not equal in terms of their quality.

Adverse yaw happens for a lot of reasons as you probably know, the most obvious ones being: the initial increase in lift as you input aileron increases the induced drag; the decreasing angle of attack of the upgoing wing and the opposite effect on the downgoing wing shifts the centre of lift of each wing, and more profile drag with the increased camber of upgoing wing the reverse of this on the other wing.

All of these things are often amplified by a longer wingspan, since the effect will induce more leverage when it is further out on a long wing; this is why it is very often a noticeable feature of gliders, since they tend to have rather long wings. There are of course other things which affect whether a wing will be susceptible to adverse yaw, and indeed things which can be done to mitigate it too in terms of design, so don't be too surprised to find it isn't necessarily a noticeable effect on an aircraft where you might reasonably expect it to be present.

Leslie George Frise, designer of things such as the Bristol Beaufighter and the Jet Provost, designed the Frise Aileron in the 1930s, which projects out from the wing a bit when deflected up specifically to increase the drag of the downgoing wing in order to reduce adverse yaw (see many mid-1930s onwards aeroplanes). Before that showed up, many aeroplanes had balance horns incorporated into the design of their ailerons in an attempt to achieve the same thing (see many WW1 biplanes), as well as to reduce control forces at speed. If you see these on an aeroplane, you know that an attempt has been made to do something about adverse yaw. On modern airliners, jet fighters, and more sophisticated GA aeroplanes, you might also see them deploy spoilers on the downgoing wing in a roll, to increase its drag a little.

Most glider pilots know that you really do have to give the majority of gliders a really serious bootful of rudder to initiate a turn, for two reasons really; one is that adverse yaw tendency and the other is that there is no propwash acting on the tailplane to make the rudder more effective. In gliding, this is especially the case when you feel a wing tip up as you touch the edge of a thermal and so immediately want to turn into that thermal. It's not uncommon to bank gliders over at very steep angles in order to stay in a thermal, so counteracting adverse yaw quickly is something glider pilots get used to, but it is something they have to watch out for when they get into something like a Cessna and modify their habit accordingly, so it is worth bearing in mind that speed and rudder input/technique will have a bearing on whether you experience adverse yaw. Be careful though; whilst it is fine to be shoving your boot down to the floor in a glider which is floating along at 40 knots, if you do that up near its Vne, you risk over-stressing the tail, and that's true for any other aeroplane too, so watch those V speeds with that rudder!

So how do you know if adverse yaw has been replicated, or even if it would be present at all on the real version of your sim aeroplane? Well, there is a test you can do to find out if your sim aeroplane is something sophisticated, or perhaps not, in terms of how it has been flight modeled, and that is to try a sideslip in it. You will certainly find that the ones which can do a convincing sideslip will generally be the ones with a more sophisticated flight model in all areas, whereas the ones which continue to maintain altitude even when you get them virtually sideways, are not really behaving as a real aeroplane would and are unlikely to be portraying other flight behaviour as well as they could do. If you want to see that in action, here is a little video which ably demonstrates what I mean...

Watch as I sideslip the A2A Piper Commanche in from a too high approach, and then see how the Carenado Beech Bonanza does with the same attempt to sideslip in from the same position. No prizes for guessing why A2A add-on cost more than Carenado ones after watching this comparison. The A2A aeroplane replicates a genuine sideslip, the Carenado one doesn't do so at all. This is the sort of thing you are paying for with a more expensive add-on:

 

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If you want to experience adverse yaw you should try the Alabeo DA42 or the Carenado DA62. With the long span wings there's, like on gliders, quite a bit of rudder required when starting/stopping a turn.

In the various YouTube reviews you will see that even RW pilots/IPs tend to totally ignore the required rudder input and let these two planes awfully slip through the turns.   

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2 hours ago, Chock said:

Watch as I sideslip the A2A Piper Commanche in from a too high approach, and then see how the Carenado Beech Bonanza does with the same attempt to sideslip in from the same position. No prizes for guessing why A2A add-on cost more than Carenado ones after watching this comparison. The A2A aeroplane replicates a genuine sideslip, the Carenado one doesn't do so at all. This is the sort of thing you are paying for with a more expensive add-on:

Oh well, Chocks usual unqualified Carenado FDE bashing.  Why are you comparing a Beechcraft Bonanza with a Piper Commanche? Do you know that the slip the same way IRL?

If you are unable to slip the default A36 and/or you don't notice a difference in the ROD, it's definitely not the airplanes fault. 

Btw, it was funny to watch how you tried to force the A36 to side slip the way you wanted, instead of doing it the way to airplane would require it. But in both cases you never achieved a stable slip, it was simply an uncontrolled wallowing through the sky (followed by a really bad off center 'arrival' in the Commanche).

 

 

 

Edited by FDEdev

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6 hours ago, DavidP said:

I think you'll find in types such as the 172 that most of the rudder is to do with engine torque. Demonstrating adverse yaw in these types, while not difficult, meant aggressively rolling the aircraft left and right and eventually you could see some sort of effect. The amount of rudder input needed on these types is often overstated by simmers.

Good point. Adverse yaw depends a lot on the speed of the aileron application and how much aileron you apply.  If you are slowly, autopilot like, rolling into a 20° banked turn with only a slight aileron deflection you will only notice (if any) very little adverse yaw.

If you rapidly slam the yoke to it's limit on the other hand you will definitely notice the adverse yaw, even in a 172.  

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7 hours ago, DavidP said:

I think you'll find in types such as the 172 that most of the rudder is to do with engine torque. Demonstrating adverse yaw in these types, while not difficult, meant aggressively rolling the aircraft left and right and eventually you could see some sort of effect. The amount of rudder input needed on these types is often overstated by simmers.

 

Tail draggers, of course, are different beasts.

Torque only affects an aircraft during takeoff, as it applies more weight (thus drag) to the left main (on american made aircraft). Torque has no effect on an aircraft in flight; the only effect coming from the engine input in flight comes indirectly from the propeller's slipstream, producing a yaw to the left and this is normally overcome (neutralized) by the fixed trim tab found on the rudder (of all Cessna and Piper aircraft) and factory set (for cruise speed). So in a turn (of more the 30 degrees bank) where more power is needed to maintain cruise speed, the slipstream effect will be added to the adverse yaw. Even if their was no adverse yaw (due to differential ailerons) you will still have to apply some rudder in the turn one way or the other. A turn to the left will now cause slipping into the turn because of too much yaw as the slipstream effect plays it's part once again, requiring rudder input in the opposite direction of the turn, though negligible at times (theory wise that is).

So in short, rudder is always needed during a turn once power beyond the cruise setting is required to maintain the cruise speed.

Even on more advanced aircraft like the B737, some rudder input (very little by the yaw damper) is used in the turn at times.

Edited by portanav
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1 hour ago, FDEdev said:

Oh well, Chocks usual unqualified Carenado FDE bashing.  Why are you comparing a Beechcraft Bonanza with a Piper Commanche? Do you know that the slip the same way IRL?

If you are unable to slip the default A36 and/or you don't notice a difference in the ROD, it's definitely not the airplanes fault. 

Btw, it was funny to watch how you tried to force the A36 to side slip the way you wanted, instead of doing it the way to airplane would require it.

 

If you read the comments in relation to that clip, you would notice I am not suggesting a Commanche and a Bonanza handle exactly the same, they just happened to be two single-engined GA aeroplanes of approximately the same three-axis control configuration I had installed in my sim which served the purpose of demonstrating that a better flight model is likely to better simulate an aspect of flight. In this case a slip, and as such, indicate that attention to detail has been paid in creating said flight model.

And for your information, I also considered using an Alabeo Tomahawk to make the comparison, and that too, is not the same as a Commanche, but it would have sufficed just as well for the point of the video, which was not to compare aeroplanes but to compare one maneuver in two aeroplanes and how their capability to perform it convincingly has or has not been simulated by their flight modeling.

If you are seriously suggesting that comments about Carenado's very well known lack of attention to detail in many respects, are in any way limited to me alone pointing them out, then you really are not paying much attention. Many other people have also commented on this. Regularly. So feel free to direct your frequent attacks at them too on occasion, instead of constantly having a go at me (and yes, I have noticed that you do this).

All aircraft, from a Tiger Moth to a Boeing 747, use the same control inputs to perform a slip, i.e. opposite aileron and rudder, not necessarily to the same degree it is true, but this is something which will occur when you feed those inputs in and it is of necessity when performing a slip, a requirement to feel around a bit for the best deflection, but it most definitely will be there. The fact that the Carenado aeroplane literally does not do a slip, instead requiring you to stick it in a dive and hope the flaps and gear will hold the speed down should be apparent from the video comparison. It's got nothing to do with not finding the correct inputs to make it simulate a slip properly, it just doesn't simulate one in even a remotely convincing manner.

Now it's certainly not the only add on aeroplane to be guilty of that by any stretch of the imagination, but it does, in this instance, serve to demonstrate how very much better the flight modeling of an A2A aeroplane is in that regard, and this is the point I was making to the O/P, that in searching for an aeroplane for the simulator which has the nuances there along with the basic controls, that is where the admittedly pricier stuff from A2A starts to justify costing a bit more.

Edited by Chock

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Please note, there is a difference between slipping and skidding. Skidding like with a car is outside of the turn, slipping is (skidding) into the turn or towards the center of the turn. The term "side-slipping" is experienced only during descent in an uncoordinated turn or deliberately by the pilot on approach (using cross-controls) to increase the aircraft's rate of descent. The latter used commonly in flapless aircraft.

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