Please fix that deflected propwash effect :-(

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Do you have a picture the explains what you're talking about? I know there is a real issue here, and I know that experienced pilots have made similar comments about DCS.

But I still don't understand. It has something to do with asymmetric induced drag from aileron deflection when there is a cross wind?

I haven't noticed any change in the P-51 since the 190's release, but I can confirm that the 190 needs a lot of aileron correction. I assumed it was torque because I still need lots of aileron when there is no wind.

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Well, the effect has certainly been here since 1.2.8 when I started flying Mustang. I also get the theory behind it, but something smells fishy about its strength indeed. That's why I just don't fly DCS props in X-wind conditions - for now.

That's why I just don't fly DCS props in X-wind conditions - for now.

Same here. I would like to see evidence or comments from pilots who have experienced this in RL. Currently I am not liking the modeled effect but waiting for evidence rather than theory.

+1 jcomm

Ok, the picture helps a lot. The text explanation still confuses me. It would help if your picture also had the wind coming from the 2 o'clock direction.

It is still here in 1.2.11

 

For me it is a true show killer :-(

 

Not the effect per se, but rather the way it is being modeled - overdone IMHO...

 

I only use the props in DCS. Should I be using any of the jets, or probably even the rotary wings, it couldn't affect me ....

 

I simply can't accept having to use, during takeoff or landing, rudder into the wind and aileron downwind, even more when the x-wind comes from your 3 o'clock and you're flying a CW prop aircraft.

 

Again, I accept the effect exists - makes all sense - as much as drag from the downgoing aileron when you use the "aileron into the wind" technique ( wind wing down... ), but

the effect itself couldn't possibly overcome the weather vane tendency, specially with a considerable x-wind component, and at a mild one, then the effect itself would be marginal...

 

I don't recall having this effect when I started using DCS World and the p51d. First became aware of it when I had the Fw190 and one day took off with a 5 m/s almost direct x-wind. I guess

it has been introduced recently ( ? )

 

I have been running many tests. As I get airborne, and gain a few meters alt., or when I come in for landing, no matter at what power settings / speeds / AoA, the effect slowly fades away ( when climbing ) or

increases ( when landing ). On a takeoff, the aircraft progressively transitions from that "nose away from the wind", and as I approach with a crab angle, the nose starts to point away from the wind the closer I

get to ground, sort of uncrabing automatically fo rme... Could it be more of a problem with ground effect? But then it would not account for the increase in induced drag from the washed upwind wing ???

jcomm is that only happening with the p51?cause i admit, i havent flown the p51 in strong crosswinds since the dora is out...with the dora though i never have to give rudder into the wind.not even at 30m/s from 90°.though once on the ground, to stay on the runway i had to give ailerons away from the wind.but that was really high wind speeds.

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On a takeoff, the aircraft progressively transitions from that "nose away from the wind", and as I approach with a crab angle, the nose starts to point away from the wind the closer I

get to ground, sort of uncrabing automatically fo rme...

Have you tried landing with stopped engine? If it behaves the same, then propwash isn't the culprit.

Have you tried landing with stopped engine? If it behaves the same, then propwash isn't the culprit.

Yep! Certainly ;-)

It works perfect on a deadstick landing (meaning, the effect doesn't show under such circumstances...).

And, btw, if you try it with any of the jets, say the a10c, the su25t..., they behave correctly too.

is this confirmed by some official or at least some tester?do they know about it?

is this confirmed by some official or at least some tester?do they know about it?

I've told Yo-Yo about it.

I don't know who are the testers, or how to reach them :-/ but I assume they might read these posts, so, let's hope they find some time, after this certainly stressing period before the release of the K4, to look at it...

I honestly don't understand the issue. As others have said a picture might be worth a dozen posts in explanation. But unless you have flown a P-51, there is no way to be certain at what point torque should be overcome by outside rolling/yawing influences. I too have issues with the P-51, especially on takeoff. There just doesn't seem to be nearly enough yaw stability between 50 - 120 mph. But I can't back that up with experience because I have none. But I do own an airplane that is far more demanding on the ground than the Mustang is reputed to be, and yet it is much more controllable. Plus I have access to many pilots who have flown or currently fly the P-51 and they all claim that it is very docile. But with all that I really have nothing more than intuition and that simply isn't good enough. It's not that I doubt the OP. In fact he is probably right. But ever since IL2 disastrously changed FMs based on player input, and the resulting uproar, no developer in its right frame of mind would consider expensive changes without hard documentation or verifiable input from a pilot experienced in type.

I honestly don't understand the issue.

Very simple really: wind is blowing from your left to right. On TO proper procedure would be to use right rudder with stick back and to the left until you gain some speed. As it is written in many manuals and text book procedures. What we have in DCS is the opposite - left rudder with stick back and to the right.

Please help me understanding the deflected propwash effect...

Well,

the sketch on that picture I posted above was the one which sort of convinced me the effect was correct, when I was first told about it. I attached it to one of the posts in this thread because indeed it:

1) Show's that DCS World is modeling a true effect, not the imagination of some developer; (*)

2) If we think about the flow that can initially wash the downwind lift generation surfaces and even part of the tail surfaces at as much as 30 m/s, then it appears that indeed it must play it's role, at least while the slipstream speed is high.

Commenting on Smoking Hole's exclamation all I can say is that it is also somehow how I felt - should I be this picky? Really? What if this is actually what happens on a Fw190 and P51? And if not, what's the big deal?

If DCS World was just another flight simulator of those which I use apart from it ( Aerowinx PSX being the other exception... ) I would simply forget about it and continue trying to convince me either it was correct or that I shouldn't really care about this detail, but there are two factors:

- I have DCS World, and particularly Yo-Yo's work in my highest consideration as far as flight dynamics modeling goes;

- I do not make great use of DCS World as a combat sim, but rather as a flight simulator, and I have my joy flying circuits around an aerodrome or between aerodromes, managing the aircraft, performing some simulated aerobatics, simulating emergencies... so, all details pertaining to the accuracy of the flight and systems modeling are very important to me. I couldn't care less about how the guns and the bullets are going to be modeled, if the bomb fuses work this or that way... but I do care about the way the radiator and cowl flaps are implemented, the pace at which the trim works, as well as the flaps, and the gear, the stall characteristics, the control response at various speeds and altitudes, etc... That is my cup of tea ( my beach as we say around here... )

Now, I have, as a private pilot, but above all as an aviation and flight simulation addict, read all sorts of books, texts, articles, studies, syllabus on Aviation, and, as THOR pointed out, I never saw mentioned in any text, no matter how and where I search, this effects of the deflected propwash, capable of turning a prop aircraft nose away from the wind. It looks to me that just as I spent years trying to convince Austin Meyer that the roll due to torque was simply overdone in X-Plane , which he finally acknowledged, I wouldn't like to get the feel that my preferred flight simulation platform has this particular feature which, I believe, is also overmodeled, unless someone proves me the contrary.

I think a good high quality flight simulator, just as DCS World, should reproduce in the most plausible way, flight. Now, operating an aircraft under crosswind conditions is the kind of task all student pilots and professional pilots have to deal and master along their careers so, I really would like to have it "perfect" in DCS World. If turbulence and shear were also modeled in DCS World ( only turbulence is, but in a rather mild way... ), then we would under windy, gusting and turbulent approaches be so occupied with landing or taking off, with our feet allover the place, that probably this effect would become "hidden", but DCS's wind is steady and doesn't shear....

Honestly, I would love to see a RW p51 pilot come here, or at PPrune, or any of my friend pilots to whom I have posed this question tell me - "José, it is perfect - that's exactly how it is IRL when we fly powerful prop aircraft. The wind deflected propwash effect is so intense that you can perfectly forget about what the books all say about how to takeoff or land in a crosswind!"

Note that for instance in the p51d or in the Dora you don't have to use full power on takeoff for the effect come alive. Even if you start slowly applying power, up to 42 inches, not more, the effect will be there!?

My guess is that something in the model is giving this effect, which is realistic and it's great to know that it's being modeled, only at a bigger dimension than it really works IRL?

I really just want to understand it better, and if needed I'll be very glad to accept it's correct and realistic. If not, then please tune it down.

Last, I really don't think that this kind of thread should be considered trolling, just in case some of you might look at it this way. I'm not a troll regarding DCS because DCS is by far my preferred prop and rotary wing flightsim, but, to give you just an example of how every developer is confronted with many options and doubts when designing an aircraft without full access to all data about it, I have to refer here Aerowinx PSX, and his unique developer, Hardy Heinlin who, since the release of the sim some 3 months ago hasn't stopped releasing new versions, almost every day, to adjust things he is still not satisfied with, and using the simulator forums to ask questions to real pilots, flight instructors, engineers about details he's not really sure about or someone, usually a B747-400 pilot and PSX user has commented! It's a continuous work towards "perfection", and this is exactly how I see, although in a much smaller scale because the focus of the platform is completely different, DCS is also evolving towards what I consider the most realistic flight and systems / training / learning / simulation platform available for combat aircraft!

(*) I haven't yet found this effect modeled in any other civil or combat flight simulator I have ever used, so, DCS is probably the first to model this effect, which is great!

Very simple really: wind is blowing from your left to right. On TO proper procedure would be to use right rudder with stick back and to the left until you gain some speed. As it is written in many manuals and text book procedures. What we have in DCS is the opposite - left rudder with stick back and to the right.

OK. That I get and agree that it doesn't sound correct with a right turning engine.

I haven't flown the Pony in such conditions lately but this is serious if it is true, at least for people who operate RL aircraft.

Don't ever memorise a bad habit or wrong move deeply or you will pull it out of nowhere when it is not wanted, aka RL stick and controls and your brain makes the wrong decision because you suddenly have TWO options that bite each other !!!

From the security point of view, this is not tolerable and actually somehow dangerous.

BTW, I might have had it but haven't payed attention to anything but what my nose does

cause there aint much time to think and make plans when you go balls to the wall.

Bit

 

From the security point of view, this is not tolerable and actually somehow dangerous.

 

 

Bit

Of course, being a flight simulation game, no one ( real pilot ) would ever use game-based learned techniques IRL :-)

Anyway, for the sake of plausibility and high quality standards that DCS World has set in terms of flight dynamics modeling, having this effect fine tuned would be great!

Of course, being a flight simulation game, no one ( real pilot ) would ever use game-based learned techniques IRL :-)

No, but the opposite is expected, and this cannot be done right now.

No, but the opposite is expected, and this cannot be done right now.

Right ;-) !

That's why I decided to be picky :-)

Of course, being a flight simulation game, no one ( real pilot ) would ever use game-based learned techniques IRL :-)

 

Anyway, for the sake of plausibility and high quality standards that DCS World has set in terms of flight dynamics modeling, having this effect fine tuned would be great!

I am not saying that RL Pilots should use DCS as a training facility.

What I am saying is that we, as a matter of fact, do have RL Pilots among us, civil and military,

and that it is not good that you need to train yourself reflexes and moves that are opposite to real life behaviour.

Your brain, if called for in emergency, may pull the wrong move cause your brain has TWO solutions for a given problem and as there is no time to think and evaluate you instantaneously

apply the outcome of what you thought is right, and that might be the wrong thing.

Same as riding two bikes with brakes reversed on the handle bar.

Would you bet that you pull the rear brake full and front only half out of the blue ?

Or would you give yourself the chance to pull the wrong lever full and other one half ???

This is what I mean with dangerous, you train yourself a bad habit.

Bit

I agree Bit,

and indeed that's also in fact the reason I would like to see it either fixed, if it really is wrong the way it is, which I think is the case, or some RW pilot of powerful prop aircraft ( I'm a rw pilot, but gliders only ) tell me it is correct happens IRL...

So far, I had no feedback from RW pilots supporting the effect the way it is modeled :-/

I only fly powerful weight/thrust ratio R/C planes like the P-47 in my Avatar. Though I usually don't harvest good response when I draw similarities between larger and heavier R/C and RL AC.

In fact some RL AC these days ( drones etc. ) are same size or smaller of what we operate. We jus often overdo power/weight a lot more, for fun reason and because of pure having the option for more power, one will do it.

When I accelerate that P-47 up in the avatar I need all I have to keep ahead of the plane. i have to work on elevator, FULL UP till considerably fast, then let go, instantly my tail comes up, then I have to SMOOTHLY pull on the elevator again until she lifts off.

WHILE I am doing that, I have to counteract more torque in relation that any RL Pony or JUG ever had with LOTS of right rudder first and slowly decrease rudder tracking aid while she speeds up, on the same stick ( left ) I also have throttle, so while I move that stick left and right for rudder I also have to move it smoothly in 1 go all the way forward, BALLS TO THE WALL, she won't lift off otherwise as she is VERY HEAVY. She would lift off early with high AOA but drop down 2 sec later like a brick, had that once with a sever gust from 2 o' clock on her 2nd flight.

So there is quite a lot to do in those 3-5 seconds on both stick in all directions all sticks.

Now imagine, you reverse the sticks, some pilots fly other way around, YUGG.... and they call you and hand you the transmitter over cause they have a bee or wasp sting etc... all happened.... now I am at controls of a plane with everything on the wrong side.

I can land that plane, but don't ask me to do anything else or any funny move and I will crash instantly in a spiral of death cause I will always first place pull the wrong stick out of fast memory.

As long as I am slowly coming in, modest turns, engine in control it's all ok as I can pre-think ahead which function does which, but don't force the brain do it ad-hoc, it won't work.

Any tail dragger will point it's nose INTO the oncoming wind as long as you are slowly moving forward as the stabilising surfaces do not yet develop enough forward stabilisation, which only comes with speed aka wind passing over the covered surfaces. As long as the wind blows harder than your mass is holding against you will end up like a church spire cock facing into the wind.

You may be able to overcome this by prop and rudder but I would be cautious.

If you are too far offset and too little space to accelerate that prop high enough so you have authority with the blast on your controls, you have no chance but call ground crew to manually position your nose in better way. Differential braking, some firm prop wash on the tail and some guts and knowing it will work and you maybe doing a successful 180°, maybe not and you have 270! facing the green or bunker :(.

Tail draggers and strong winds never go well together, and even worse when the plane is slow and the wind is strong.

Bit

A take my hat to you, and any aeromodelist Bit !!!

I tried hard to learn how to control an RC aircraft, but never managed to :-(

It is just too difficult / complex for me, plus the fact that they're expensive too!

Had a couple of 2 channel RC gliders, did well while they were ahead of me, flying away or across, but the moment they passed to my back, for landing ( in the mountain top ), things usually got out of control -my brain never adapted to the inverted roll and yaw :-/

A fellow simmer and RW pilot but also RC modeler, from the AVSIM forums, has contributed with much of his RW aeromodelist and pilot experience in many threads at that site, specially trying to point out some misconceptions some simmers make of flight dynamics and effects. I have long told him to try DCS... maybe one day :-)