Rudder Discussion

[Sokol1_br]

I didn't know it had an asymmetric camber, learn something new everyday, thanks for the information.

 

:D http://forums.eagle.ru/showpost.php?p=2419565&postcount=242

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[NineLine]

Because fixes done in the 2.0.0 build dont float over as easy to the older versions, so most likely dont expect anything till 1.5 or later.

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[Crumpp]

Its semantics. To me kicking rudder and ripping wings off is a little bit funny :) Sorry if I came across as rude, it wasn't the idea behind it.

 

I know, YoYo has said that its comming, and I am still waiting. I was rather trying to show others that what we have now is not correct, yet I didn't say that its not beeing worked on.

 

OP was not actually talking about the same issue as I am. He seems to be claiming that the 109 has not enough rudder authority to keep the plane straight on take off... which I don't share as I find it quite easy to keep the plane on track :)

 

Sure, we know what maneuvering speed is, we learned it in private pilot ground school. You know, Va—Design Maneuvering Speed. "This is the maximum speed at which the limit load can be imposed (either by gusts or full deflection of the control surfaces) without causing structural damage."

 

http://www.avweb.com/news/features/The-Risks-of-Maneuvering-Speed-Myths-222680-1.html

 

http://www.ntsb.gov/news/press-releases/Pages/NTSB_Says_Pilots_Excessive_Rudder_Pedal_Inputs_Led_to_Crash_of_American_Flight_587;_Airbus_Rudder_System_Design_Amp;_Eleme.aspx

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[SlipBall]

So thanks to jcomm I discovered that my rudder was not calibrated properly.

 

Even though my CH testing software assured me that it was correct, and so I was mistakenly blaming the aircraft's rudder all of these months, when in fact it was the driver...I deleted all of my drivers CH controllers and reinstalled the latest CH software. I am happy to report and finding that I have even greater respect for this aircraft now, and my field landings are now less negatively eventful for me :)

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[SlipBall]

but still thinking the rudder should be looked at as far as the on the ground control goes

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[SlipBall]

seems odd to me to have NO nose movement to the right with all of that airflow...not even an inch! :pilotfly:

 

Edited August 4, 2015 by GT 5.0

[Sporg]

seems odd to have NO nose movement to the right :pilotfly:

 

Well, if you think of it logically it is not:

 

The rudder works only by the stream of air that passes it.

The rudder on a 109 is very small.

Therefore it needs quite a bit of air in order to get "grip".

 

On the other hand, in the front you have a big propeller driven by a big engine.

The torque and air stream of this propeller has a strong tendency to pull you to the left.

 

Thus, when you have this small rudder, it is close to useless at slow airspeeds, and thus cannot overcome the force of the propeller.

However, it can of course "help" the propeller when turning left.

 

In order to maneuver on the ground, you simply must use the brakes, the rudder forces are not strong enough to help you there.

(Notice, on the P-51, as well as the Dora, you also need brakes in order to make sharp turns on the ground. And the P-51 even has steering in its tail wheel.)

 

When you take off you need to make a balance between torque of the propeller and air stream on the rudder:

 

I have noticed that if you start by gently opening the throttle you go left.

That is because of the lack of sufficient air stream on the rudder.

 

However, if you go full throttle, the airplane also has a tendency to weer to the left.

This is because the torque and spiral air stream of the propeller are so strong that the rudder cannot overcome the forces of them.

 

Only when giving high but not emergency throttle do you get a balanced take off, where you can use the rudder to keep you straight and even go slightly right if you want to.

 

Here you get a forced air stream from the propeller, but not so high torque that you cannot compensate with the small rudder.

And after a little acceleration you have so high speed that the rudder can get "grip".

 

Does this make sense?

 

It just tried it and I got exactly the reactions I describe above.

Especially it was fun to give a little thrust of throttle when standing still and see how the airplane was pulled left by the forces of the torque.

No amount of rudder helped me here.

 

Actually I think it is a magnificent simulator to have captured these forces so well.

 

I have found a little Youtube video that show quite well what I have explained above.

It is a Bf 109-E4 in the clip, but the same principles apply.

In

he is taxiing and I think one can hear that he uses the brakes.

In

he takes off and here you can see how he several times need to apply almost full right rudder in order the keep the airplane straight.

 

 

To me the Kurfürst rudder seems spot on and I can't really see what we could demand of change (except of course the high speed stiffening that ED has already said they will apply.).

 

PS:

The Erich Brunotte video at

, that Thor quoted earlier, says exactly the same again: Little rudder authority when you take off, sometimes not enough and needs to be compensated by braking. Edited August 4, 2015 by Sporg

[SlipBall]

Well, if you think of it logically it is not:

 

The rudder works only by the stream of air that passes it.

The rudder on a 109 is very small.

Therefore it needs quite a bit of air in order to get "grip".

 

On the other hand, in the front you have a big propeller driven by a big engine.

The torque and air stream of this propeller has a strong tendency to pull you to the left.

 

Thus, when you have this small rudder, it is close to useless at slow airspeeds, and thus cannot overcome the force of the propeller.

However, it can of course "help" the propeller when turning left.

 

In order to maneuver on the ground, you simply must use the brakes, the rudder forces are not strong enough to help you there.

(Notice, on the P-51, as well as the Dora, you also need brakes in order to make sharp turns on the ground. And the P-51 even has steering in its tail wheel.)

 

When you take off you need to make a balance between torque of the propeller and air stream on the rudder:

 

I have noticed that if you start by gently opening the throttle you go left.

That is because of the lack of sufficient air stream on the rudder.

 

However, if you go full throttle, the airplane also has a tendency to weer to the left.

This is because the torque and spiral air stream of the propeller are so strong that the rudder cannot overcome the forces of them.

 

Only when giving high but not emergency throttle do you get a balanced take off, where you can use the rudder to keep you straight and even go slightly right if you want to.

 

Here you get a forced air stream from the propeller, but not so high torque that you cannot compensate with the small rudder.

And after a little acceleration you have so high speed that the rudder can get "grip".

 

Does this make sense?

 

It just tried it and I got exactly the reactions I describe above.

Especially it was fun to give a little thrust of throttle when standing still and see how the airplane was pulled left by the forces of the torque.

No amount of rudder helped me here.

 

Actually I think it is a magnificent simulator to have captured these forces so well.

 

I have found a little Youtube video that show quite well what I have explained above.

It is a Bf 109-E4 in the clip, but the same principles apply.

In

he is taxiing and I think one can hear that he uses the brakes.

In

he takes off and here you can see how he several times need to apply almost full right rudder in order the keep the airplane straight.

 

 

To me the Kurfürst rudder seems spot on and I can't really see what we could demand of change (except of course the high speed stiffening that ED has already said they will apply.).

 

PS:

The Erich Brunotte video at

, that Thor quoted earlier, says exactly the same again: Little rudder authority when you take off, sometimes not enough and needs to be compensated by braking.

 

 

Still it is hard for me to accept zero response to that airflow...every action has an reaction they say, so to have nothing raises my eyebrows :P...@4:54 that is some turn, I am not able to simulate it

 

also some more for you to ponder here:

http://simhq.com/forum/ubbthreads.php/topics/4153677/DCS_109_rudder,_turns_and_slat#Post4153677

Edited August 4, 2015 by GT 5.0

[NineLine]

Still it is hard for me to accept zero response to that airflow...every action has an reaction they say, so to have nothing raises my eyebrows :P...@4:54 that is some turn, I am not able to simulate it

 

also some more for you to ponder here:

http://simhq.com/forum/ubbthreads.php/topics/4153677/DCS_109_rudder,_turns_and_slat#Post4153677

 

It all comes down to "I think" or "I believe" (especially that SimHQ post)... I would rather Trust Yo-Yo's methods of determining if something is working right, hard data and pilot input.

 

I am not seeing an issue here.

[SlipBall]

It all comes down to "I think" or "I believe" (especially that SimHQ post)... I would rather Trust Yo-Yo's methods of determining if something is working right, hard data and pilot input.

 

I am not seeing an issue here.

 

 

I'm sure that he will take a look if he hasn't already

 

...only Yo Yo can change it and he certainly would if he thinks it is off even a little bit...I'll stop bringing it up though, because to keep doing so would become annoying to the community :P

[NineLine]

I'm sure that he will take a look if he hasn't already

 

...only Yo Yo can change it and he certainly would if he thinks it is off even a little bit...I'll stop bringing it up though, because to keep doing so would become annoying to the community :P

 

He talks to Erich from time to time still as well, I know he brings up concerns even if he is convinced they are correct... so dont worry, it will atleast be looked at.

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[[DBS]TH0R]

@ GT 5.0: Have you tried full sick forward when applying small throttle bursts? There is an in cockpit video of G4 Red 7 taxing after landing and the pilot uses full sick forward in combination with throttle bursts to turn (in combination with manual prop pitch set to 11:45). Presumably to help ease the pressure on the tail wheel since German AC were so tail heavy in comparison to the western AC...

Edited August 6, 2015 by T}{OR

[NineLine]

I thought you were convinced here it was ok?

 

http://forums.eagle.ru/showpost.php?p=2437833&postcount=1

 

Regardless, how is this on topic with the OP?

 

And, there's still that feature, unique to DCS World prop aircraft FDM, that responds for the tendency to veer downwind, against weathervane, when under a strong x-wind component...

 

While I even accepted it as a mathematical possibility ( confined to the model being used in DCS ), my brain refuses to accept that the deflected propwash effect could, indeed, cause such a counter-intuitive effect.

 

It affects all prop fighter aircraft in DCS, with the K4 being an exception given the intense prop effects pulling and rolling it to the left during takeoff, and I have a huge difficulty understanding that IRL an aircraft would "pull" to the right with wind blowing strong from the left, during the takeoff run, even requiring the pilot to use upwind rudder.

 

Yo-Yo mentioned in some other thread that he was once next to a p51d on a windy day, during engine startup, and noticed the deflected propwash because the wind was blowing close to 90º relative to the aircraft longitudinal axis, but heck! during takeoff, I can't imagine using upwind rudder t stay on the rw centreline :-(

 

Yes the mathematics can tell Yo-Yo this is as outcome ( even if unexpected ) in his FDM, but IMO, there most be something out of the equation that he didn't find yet.

 

I have been unable to confirm these effect when asking many RW pilots, even some who operate powerful prop agricultural aircraft, sometimes in rather adverse wind conditions, from the aerodromes I operate my glider. All of them are unanimous ( even look at me as thinking - José must have been drinking something... ) that the usual away from the wind rudder and into the wind aileron is always the rule, starting from the very beginning of the takeoff run. That's certainly what I do ( I don't have a prop in my glider ) and in some models ( lak-17 being a good example ) I can easily run out of rudder to overcome the weathervane effect....

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[NineLine]

What is wrong with the K4's handling on the ground? :huh:

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[NineLine]

I find it handles pretty close to what Erich described. I think you are over-estimating how effective the rudder will be on the ground, even with a burst of power... most videos dont show all that is going on, how much brake is being used, where the stick placement is exactly, and how much rudder... its been pointed out already of course. I think ED would need harder data for a fix, right now it handles quite nice for me... although landings still scare the crap out of me... but thats all pilot skill in that case ;)

[Anatoli-Kagari9]

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Edited August 17, 2015 by jcomm

[NineLine]

Yes, following Erich's words have made landings less of a life or death matter for me :)