dcs mustang Rudder effect much too strong

[bestan]

hi

 

i just got the mustang and went for a try

 

that plane doesnt feel very real to me

 

for instance rudder input at high speed eg 400km/h affect the plane far too much

 

i am an rc pilot and it is much different - means once the plane has much speed rudder has little effect

 

is this real? im not a full scale pilot but consider fix yaw stabilicer ....

[PhoenixBvo]

RC flight cannot be compared to full scale flight with respect to such flight dynamics effects. For one thing, the Reynolds numbers are totally different. Meaning you're talking about another flow regime.

[Merlin-27]

hi

 

i just got the mustang and went for a try

 

that plane doesnt feel very real to me

 

for instance rudder input at high speed eg 400km/h affect the plane far too much

 

i am an rc pilot and it is much different - means once the plane has much speed rudder has little effect

 

is this real? im not a full scale pilot but consider fix yaw stabilicer ....

 

Not sure I'd call 400km/h "high speed" in the Mustang. Now, if you said 400mph I'd would be curious how the rudder reacts in relation to RL.

 

I fly R/C as well. You are saying the rudder loses authority at high scale speeds? Have you seen seen Knife Edge maneuvers performed?

 

[Konrad Friedrich]

The guy who was on the controls of the white/yellow plane (at ca.30") is not only pretty damn good.

He has cough, cough... (sorry) big hairy balls... :shocking:

Even if it's a rc plane - this needs real (I mean real) control of that thing! Wow.

This needs trust in your own rc piloting abilities and a good bunch of courage... :thumbup:

Nice video!

Edited June 22, 2013 by Konrad Friedrich

[Echo38]

RC flight cannot be compared to full scale flight with respect to such flight dynamics effects. For one thing, the Reynolds numbers are totally different. Meaning you're talking about another flow regime.

 

Indeed--R.C. model P-38 Lightnings usually have enlarged vertical stabilizers compared to the real one, to enhance stability; when scaling down the model, the size of the aerodynamic surfaces relative to the air molecules changes by hundreds of percent, and it ended up making the miniature P-38s very unstable where the real one was very stable.

[Der_Fred]

Indeed--R.C. model P-38 Lightnings usually have enlarged vertical stabilizers compared to the real one, to enhance stability

I wouldn't be too sure about that.. :) the power to weight ratios, prop wash..etc.. is so much more on RCs, add a bigger tail section and you have very sensitive controls.. especially wrt rudder.

[Der_Fred]

To go back to the OT

that plane doesnt feel very real to me for instance rudder input at high speed eg 400km/h affect the plane far too much

I think you're talking more of the yaw inertia.. which I agree, it needs more damping. At 400mph... there would be significant forces on all control surfaces that the pilot would have to counteract... Some 'useless information' => IL2 has modeled this years back. : )

[Anatoli-Kagari9]

I also do not know if this

is modeled in the DCS P51 d. Skip to 15:18 in the A2A video to see what I mean :-)

[Echo38]

the power to weight ratios, prop wash..etc.. is so much more on RCs, add a bigger tail section and you have very sensitive controls.. especially wrt rudder.

 

The rudder isn't what they enlarge, it's the stabilizer itself. They often make them 33% bigger, citing insufficient stability when the model is to scale. (The real P-38 had no such stability problems--it was a remarkably stable gun platform.)

[bluepilot76]

I think the problem is that in RL a pilot would not be strong enough to deflect the rudder pedal by much at high speed.You cannot experience this with your PC flight stick or RC controller.

If he was strong enough the fin would probably break off. This has happened to airliners where the controls are powered and the pilot makes too big a deflection.

[bluepilot76]

I think the problem is that in RL a pilot would not be strong enough to deflect the rudder pedal by much at high speed.You cannot experience this with your PC flight stick or RC controller.

If he was strong enough the fin would probably break off. This has happened to airliners where the controls are powered and the pilot makes too big a deflection.

[Weta43]

At 400mph... there would be significant forces on all control surfaces that the pilot would have to counteract... Some 'useless information' => IL2 has modeled this years back. : )

 

 

I think the problem is that in RL a pilot would not be strong enough to deflect the rudder pedal by much at high speed.You cannot experience this with your PC flight stick or RC controller.

 

 

I think it's an interesting question what approach to take about this - I've wondered about it myself often,

 

It's true, as speed goes up, stick forces rise with it - which you can't feel with (most) PC joysticks, and people can end up putting in unrealistically large control inputs at high speed.

 

What to do about that ?

 

You can either model the flight control system as it exists, and rely on the 'pilot' to use realistic inputs ( the approach taken here ), which as mentioned allows users to make 'unrealistically powerful' inputs if they make unrealistic (for the speed) movements of the controls, or you can 'script' the responses of the input device (as seems to be suggested above) and make it that the 'pilot' cannot input unrealistic forces - even if they make unrealistic stick movements.

It was essentially the same question that had to be asked about the Huey - do you make it so that to fly realistically you have to make realistic inputs - even though that's possibly harder in a PC simulation than real life because some of the real life clues about stability etc are missing, or do you 'assist' the pilot by adding a degree of stability to the SIM's FM that doesn't exist in real life to assist PC pilots as they learn ?

 

Do you 'script' the FM to force relistic behaviour on the pilot, or do you provide an accurate FM, then let the PC pilot deal with the dificulty of flying realistically on a PC ?

 

Personally - I like the idea of the 'make the FM correct and let people learn to use it' approach more than the 'delberately modify (script) the FM to make it behave realistically even when given unrealistic inputs' approach ...

[Echo38]

At 400mph... there would be significant forces on all control surfaces that the pilot would have to counteract... Some 'useless information' => IL2 has modeled this years back. : )

 

And, unsurprisingly, IL-2's modelling of it was horribly wrong. Another several-hundreds-of-percent error by Mr. Maddox ...

 

I think the problem is that in RL a pilot would not be strong enough to deflect the rudder pedal by much at high speed.

If he was strong enough the fin would probably break off. This has happened to airliners where the controls are powered and the pilot makes too big a deflection.

 

I doubt the average pilot would be unable to deflect full rudder at any speed short of transonic, and Second World War fighters (the jets excepted) had a hard time getting to that sort of speed, anyway. As for structural failure, well, airliners are very much not fighters. While it's true that deflecting rudder too much at too high a speed stresses the airplane, I'd wager that a fighter is going to be able to maintain vastly more rudder deflection at speed than any airliner.

Edited July 2, 2013 by Echo38

[sobek]

I doubt the average pilot would be unable to deflect full rudder at any speed short of transonic

 

Yo-Yo listed the control forces for full rudder deflection at several speeds once and they were indeed exorbitant. Full rudder deflection is impossible at anything than slow speeds. This has been on the wishlist from the start, but probably wasn't modelled yet due to time constraints.

[Nealius]

It would be nice if it could be tweaked a bit. Once airborne after takeoff and 6* right rudder the plane naturally wanders off to the right. Any attempt at using left rudder with my twist axis and I have a lateral porpoising effect. Centering trim after takeoff results in a sudden tendency to yaw/dutch-roll to the left (I guess from torque) but right rudder to compensate again results in a lateral porpoising.

[bluepilot76]

And, unsurprisingly, IL-2's modelling of it was horribly wrong. Another several-hundreds-of-percent error by Mr. Maddox ...

 

 

 

I doubt the average pilot would be unable to deflect full rudder at any speed short of transonic, and Second World War fighters (the jets excepted) had a hard time getting to that sort of speed, anyway. As for structural failure, well, airliners are very much not fighters. While it's true that deflecting rudder too much at too high a speed stresses the airplane, I'd wager that a fighter is going to be able to maintain vastly more rudder deflection at speed than any airliner.

 

I am sure that structural failure did happen to fighters flying too fast. I have read it, sorry I cant provide any references. (I am sure it also happens in the sim, definately in the case of the A10)

 

Also if you look at the envelope for aircraft there is a portion where full control deflections are allowed and will not cause structural failure. On a modern airspeed indicator this is denoted by the green arc. The amber arc denotes area where structural failure could occur with full deflection. This might not be shown on archaic P51 ASI but you can be sure that the laws of physics have not changed since WWII.

 

I was not intending to imply that DCS has done a bad job, I think the reaction of the P51 is excellent (certainly in pitch) and soon provides the diligent pilot with a feeling with how much deflection is just enough and how much is too much.

 

You can always reduce your rudder sensitivity or make it curved, should help

[Echo38]

Yo-Yo listed the control forces for full rudder deflection at several speeds once and they were indeed exorbitant. Full rudder deflection is impossible at anything than slow speeds.

 

Huh. Any idea why the rudder would be so much more stiff than the elevator?

 

I am sure that structural failure did happen to fighters flying too fast.

 

Yes, of course it did (Ralph Virden immediately comes to mind), but comparing fighters and airliners isn't a good idea. Airliners suffer structural failure far more easily than fighters. They simply aren't designed for hard maneuvers. Ever seen an airliner pull a split-S? Neither have I.

Edited July 2, 2013 by Echo38

[sobek]

Huh. Any idea why the rudder would be so much more stiff than the elevator?

 

What leads you to believe that you can pull full elevator at high speeds? Disregard the fact that it would kill the pilot and cause structural failure of the plane, it just isn't humanly possible due to the forces involved.

[Nealius]

 

You can always reduce your rudder sensitivity or make it curved, should help

 

The only way to adjust it properly in my case would be to somehow get the rudder's length of travel to match my joystick's length of travel. The deadzone doesn't really work. I can twist the stick within that deadzone area and not have any problems, but the moment I NEED rudder and go outside the deadzone the yaw is practically uncontrollable.

[Weta43]

The deadzone doesn't really work. I can twist the stick within that deadzone area and not have any problems, but the moment I NEED rudder and go outside the deadzone the yaw is practically uncontrollable.

That's not my experience -

Perhaps a track showing your problems ?

 

In the mean time I suggest :

1/Take the dead-zone right out,

2/ Set the curve back to straight

and

3/ be gentle and progressive with your inputs

 

Start by removing the dead-zone & see how that feels, then maybe move to straightened curves.

[Nealius]

Deadzone was at 10, no curves. I'll record a track with 0 deadzone tonight. The yaw/dutch-roll is worse on takeoffs and landings.

[Yo-Yo]

Personally - I like the idea of the 'make the FM correct and let people learn to use it' approach more than the 'delberately modify (script) the FM to make it behave realistically even when given unrealistic inputs' approach ...

 

Yes, you are right. I wonder, why NOBODY critisizing inputs did not noticed that maximal deflection of the eudder and ailerons are restricted using constant maximal force criteria. Ailerons used the standard value most of tests were provided. It is a feature by design to have the planes standard regarding their roll rate curves. Rudder is limited too but we leave more space to deflect it, because under adrenaline you can pull hard.

For those who do not understand why the rudder is so stiff I can gift a word "anti-booster tab". I can say that rudder pedal are EXTREMELY stiff - pulling hard I did not feel any significant movement of the pedal but the effect was predictable as I expected.

[Echo38]

What leads you to believe that you can pull full elevator at high speeds? Disregard the fact that it would kill the pilot and cause structural failure of the plane, it just isn't humanly possible due to the forces involved.

 

Hrm. I was under the impression that the limiting factor here was G tolerance rather than arm strength. It's been about a decade since I was looking at this stuff, but I'm sure pilots have over-stressed aircraft in the Second World War by pulling too much back-stick. Well, I suppose it depends on where your trim's at.

[Yo-Yo]

Hrm. I was under the impression that the limiting factor here was G tolerance rather than arm strength. It's been about a decade since I was looking at this stuff, but I'm sure pilots have over-stressed aircraft in the Second World War by pulling too much back-stick. Well, I suppose it depends on where your trim's at.

 

THe ailerons "freeze" at high speed but elevator force for 1g is relatively low so it was possible to overstress the plane before elevator becomes "frozen". I mean "frozen" as extremely high forces on controls.

 

To range the controls of the Mustang by hinge forces: elevator, ailerons, rudder.

[Yo-Yo]

Hrm. I was under the impression that the limiting factor here was G tolerance rather than arm strength. It's been about a decade since I was looking at this stuff, but I'm sure pilots have over-stressed aircraft in the Second World War by pulling too much back-stick. Well, I suppose it depends on where your trim's at.

 

THe ailerons "freeze" at high speed but elevator force for 1g is relatively low so it was possible to overstress the plane before elevator becomes "frozen". I mean "frozen" as extremely high forces on controls.

 

To rank the controls of the Mustang by hinge forces: elevator, ailerons, rudder.