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Old 09-15-2020, 01:53 PM   #31
Q-Tip91
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Originally Posted by pmiceli View Post
In the real airplane, that 6 degrees is supposed to give you a properly trimmed rudder during the initial climb. It is in no way meant to provide adequate rudder deflection during takeoff.
Eh, well you kind of did in a more eloquent way. What's interesting is during his part 3 (flight) he adjusts rudder trim several times.
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Old 09-15-2020, 04:30 PM   #32
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This guy has different opinion about not using trim in p-51 at all. He is kind of p-51 guru nowadays.
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Old 09-15-2020, 04:52 PM   #33
Lefty91
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Originally Posted by pmiceli View Post
In the real airplane, that 6 degrees is supposed to give you a properly trimmed rudder during the initial climb. It is in no way meant to provide adequate rudder deflection during takeoff.
Why would the real P51 pilot then trim his aircraft 5 degrees BEFORE takeoff and keep it there until after he's airborne then? This would tell me that it absolutely is a means to provide adequate rudder deflection...
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Old 09-15-2020, 10:49 PM   #34
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Why would the real P51 pilot then trim his aircraft 5 degrees BEFORE takeoff and keep it there until after he's airborne then? This would tell me that it absolutely is a means to provide adequate rudder deflection...
A basic understanding of physics and trim tabs is required to understand what I am taking about.

A trim tab is a control surface that is deflected in order to deflect the control surface it is mounted on.

It relies on the air flowing past it to provide the force it uses to move the control surface it is mounted on.

If you deflect the trim tab to the left, air pressure on it will move the rudder to the right. Remember air pressure on the rudder is opposing this movement.

If you deflect the trim tab 6 degrees when the aircraft is parked, the rudder will not move. The same deflection at 400 mph will provide a great deal of force to deflect the rudder.

Throughout the takeoff the yaw force provided by the trim set at 6 degrees will vary from zero up to the maximum force when the aircraft reaches its climb speed. The 6 degrees of deflection is chosen so that the rudder is approximately properly trimmed when this speed is achieved. Before this speed, the pilot must do pilot stuff. He must input the appropriate rudder with his foot. This will vary as the speed and power changes throughout the takeoff.
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Old 09-15-2020, 10:53 PM   #35
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This guy has different opinion about not using trim in p-51 at all. He is kind of p-51 guru nowadays.
In the real airplane, absolutely.

DCS P-51 rudder trim is unnecessary.
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Old 09-15-2020, 11:37 PM   #36
Lefty91
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Originally Posted by pmiceli View Post
A basic understanding of physics and trim tabs is required to understand what I am taking about.

A trim tab is a control surface that is deflected in order to deflect the control surface it is mounted on.

It relies on the air flowing past it to provide the force it uses to move the control surface it is mounted on.

If you deflect the trim tab to the left, air pressure on it will move the rudder to the right. Remember air pressure on the rudder is opposing this movement.

If you deflect the trim tab 6 degrees when the aircraft is parked, the rudder will not move. The same deflection at 400 mph will provide a great deal of force to deflect the rudder.

Throughout the takeoff the yaw force provided by the trim set at 6 degrees will vary from zero up to the maximum force when the aircraft reaches its climb speed. The 6 degrees of deflection is chosen so that the rudder is approximately properly trimmed when this speed is achieved. Before this speed, the pilot must do pilot stuff. He must input the appropriate rudder with his foot. This will vary as the speed and power changes throughout the takeoff.
Very good, so given all that you just explained, again, why setting rudder trim at 5 degrees before takeoff and not wait until you reach a speed that would require you to make those adjustments? I'm not understanding why I see a pilot do that before he even leaves the ground and you mentioning how it's unnecessary..
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Old 09-16-2020, 12:17 AM   #37
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Originally Posted by pmiceli View Post
In the real airplane, absolutely.

DCS P-51 rudder trim is unnecessary.
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Try to simulate being a pilot.
You have talked yourself in a circle. No matter though. I think the OP has plenty of things to try now.
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Old 09-16-2020, 05:16 AM   #38
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Originally Posted by pmiceli View Post
In the real airplane, absolutely.

DCS P-51 rudder trim is unnecessary.
In game as well, if you want to put any inputs like flying hands off
So answer is, you need elevator and rudder trim for hands off flying in DCS as well as in real life.
With constant needs of change.
This was an issue of OP.
No matter what hardware are you using, this plane require lots of trimming.
Flying this plane w/o constant trimming in DCS is against real life.But this is a game everyone fly in the way as he likes.
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Old 09-16-2020, 05:24 AM   #39
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A basic understanding of physics and trim tabs is required to understand what I am taking about.

Throughout the takeoff the yaw force provided by the trim set at 6 degrees will vary from zero up to the maximum force when the aircraft reaches its climb speed.
I would disagree with that, elevator and rudder trim tabs are effecting control surfaces from very begging of takeoff, as soon as power is applied ruder and elevator trimming system is affecting control surfaces, it is increasing with airspeed.
But there is no magic speed like 100 mph at which trim system starts to work, at 90 mph rudder will be deflected too.
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Old 09-16-2020, 06:49 AM   #40
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Pimicelli is right in principle - though perhaps would be better to rudder trim is useless in all sims not just DCS. This is because we have no air load that can be transmitted through our rudder pedals.

The most important thing to understand is that rudder trim has absolutely no effect on the total amount of rudder authority; this is restricted by the size, shape and limits of travel of the rudder. Trim cannot increase this.

Trim simply allows you to set a dynamic 0 foot force position for making flight comfortable or in the case of take-off, easing foot load and allowing better control.

As such, unless you own force feedback pedals, use of rudder trim would not be that beneficial.
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