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Thread: A question about ramblin_jack's trim for performance thread

  1. #1

    Default A question about ramblin_jack's trim for performance thread

    Hi, I read jack's post. It's very helpful to my understanding of the flight dynamics. Here are some questions:
    1. Say I have a perfectly trimmed plane flying straight. Then I do a 45dgree banking turn to left. Suppose I am able to maintain the speed. Would the ball go left? What I am trying to get at is that the ball only gets affected by speed changes or it would also change depended on attitude change?
    2. Also, in the case of beating a retreat in high speed. In stead of retrimming for high speed, can I just step on rudder to keep ball centered? Would that have detrimental effect on speed?

    Any help would be great. Thanks

  2. #2

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    Pandacat,

    I believe RJ is out of town for a couple of days; I'm sure he'll answer your inquiry upon his return.
    Pers

    Ahh, isn't he such an Angel?
    How could you possibly shoot at him?

  3. #3

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    Quote Originally Posted by pandacat View Post
    1. Say I have a perfectly trimmed plane flying straight. Then I do a 45dgree banking turn to left. Suppose I am able to maintain the speed. Would the ball go left? What I am trying to get at is that the ball only gets affected by speed changes or it would also change depended on attitude change?
    I'll take a crack at answering... (just remember what they say about advice, it's worth what your paid for it ) Anytime the airplane is not properly coordinated in flight the ball moves to the left or right. As you bank into a turn your high wing must travel farther (therefore faster) then the low wing which will contribute to higher drag on the high wing then the low wing. Depending on the aileron design deflecting up on the low wing and down on the high wing will also cause a differential in drag (deflecting down usually causes more drag). Now you have two effects of the turn increasing drag on the high wing which will cause the airplane to "yaw" (rotate on its horizontal axis) in the direction of the high wing. Yaw will cause the ball to move off center. To correct this you would use the rudder. If you keep your turn coordinated using the rudder the ball will remain centered. The phrase "step on the ball" applies here. The direction the ball moves will tell you which rudder peddle to step on to properly coordinate the turn. You wouldn't normally use trim to coordinate in the turn and after you level out if you have not lost any airspeed then you should not have to adjust trim. However, unless you add power or trade altitude for speed you will almost certainly lose speed in the turn.

    Quote Originally Posted by pandacat View Post
    2. Also, in the case of beating a retreat in high speed. In stead of retrimming for high speed, can I just step on rudder to keep ball centered? Would that have detrimental effect on speed?
    Short answer is YES. All the trim tab does is move the rudder surface using aerodynamic forces. What you should actually be doing when you trim is holding the airplane coordinated with the rudder peddles and using the trim to then eliminate the force you have to apply to the rudder peddles with the trim tab. Unfortunately this doesn't work on the simulator as it does in an actual airplane. In a real airplane as you trim out the force required to hold the rudder where it needs to be the rudder peddles would not return to a center position, they would be in the same position you were holding them in. In the simulator (unless you spent BIG $$$$) when you are properly trimmed your rudder peddles will end up centered (neutral).
    Jinks

    "For most people the sky is the limit, for the pilot the sky is home" - unknown


  4. #4

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    In answer to your first question: If you are flying a perfectly trimmed airplane and enter a 45 degree back turn (in either direction), in order for you to maintain altitude you will have to increase back pressure which in turn increases lift which in turn increases drag, which reduces the aircraft speed. With a reduction in speed your previous trim settings are not valid. That has nothing to do with the turn, and all to do with the effects of torque and slip stream and "P" factor associated with the speed reduction and the higher angle of attack needed to maintain altitude. For example, as you enter a left turn, you would apply left rudder to keep the ball in the center, and once you are stable in the turn, you might even need a little right rudder to counter act the left turning tendencies associated with the before mentioned torque, slip stream, and "P" factor. When entering the right turn you would need to apply right rudder initially (and in greater force the the left turn), to keep the ball centered and you might even need some right rudder while in the turn. That's the long answer, here is the short answer: From a straight and level steady state of flight, it is speed that affects the rudder trim that keeps the ball in the center.

    In answer to you second question: If you are beating a quick retreat, the main thing is to get out of Dodge a quickly as possible. As your speed increases, the previous trim setting will over trim the airplane and yes you will have to apply left rudder or left rudder trim to keep the aircraft in trim and gain the greatest airspeed in the dive. Either one will displace the rudder and cause minimal drag, but far less drag than flying the airplane out of trim. Eventually, when you level off either at tree top level or when it is apparent that you pursuer has given up the chase, your aircraft will return to it's original speed and the trim setting previously set will once again be properly set.

    I like to enter the combat area in level flight at combat speed with a properly trimmed airplane. As I engage the enemy I use rudder as opposed the trim the keep the ball centered. Trimming the airplane takes away from the battle when you should be totally outside the airplane. I know that when my speed increases I have to add left rudder in varying degrees relative to my increase in speed from my original combat speed. I know that if I decrease my speed I have to add right rudder in varying degrees depending on how much my speed is reduced from my combat speed.

    So, the shortest of all answers is the from a properly trimmed airplane, it is speed that affects trim and not attitude.

    Hope this answers you questions and feel free to ask away.

    Ramblin'jack
    Last edited by ramblin_jack; 08-18-2013 at 01:53 PM.


    "The most important branch of aviation is pursuit, which fights for and gains control of the air"
    U.S. Brigadier General William Mitchell

  5. #5

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    Quote Originally Posted by ramblin_jack View Post
    In answer to your first question: If you are flying a perfectly trimmed airplane and enter a 45 degree back turn (in either direction), in order for you to maintain altitude you will have to increase back pressure which in turn increases lift which in turn increases drag, which reduces the aircraft speed. With a reduction in speed your previous trim settings are not valid. That has nothing to do with the turn, and all to do with the effects of torque and slip stream and "P" factor associated with the speed reduction and the higher angle of attack needed to maintain altitude. For example, as you enter a left turn, you would apply left rudder to keep the ball in the center, and once you are stable in the turn, you might even need a little right rudder to counter act the left turning tendencies associated with the before mentioned torque, slip stream, and "P" factor. When entering the right turn you would need to apply right rudder initially (and in greater force the the left turn), to keep the ball centered and you might even need some right rudder while in the turn. That's the long answer, here is the short answer: From a straight and level steady state of flight, it is speed that affects the rudder trim that keeps the ball in the center.

    In answer to you second question: If you are beating a quick retreat, the main thing is to get out of Dodge a quickly as possible. As your speed increases, the previous trim setting will over trim the airplane and yes you will have to apply left rudder or left rudder trim to keep the aircraft in trim and gain the greatest airspeed in the dive. Either one will displace the rudder and cause minimal drag, but far less drag than flying the airplane out of trim. Eventually, when you level off either at tree top level or when it is apparent that you pursuer has given up the chase, your aircraft will return to it's original speed and the trim setting previously set will once again be properly set.

    I like to enter the combat area in level flight at combat speed with a properly trimmed airplane. As I engage the enemy I use rudder as opposed the trim the keep the ball centered. Trimming the airplane takes away from the battle when you should be totally outside the airplane. I know that when my speed increases I have to add left rudder in varying degrees relative to my increase in speed from my original combat speed. I know that if I decrease my speed I have to add right rudder in varying degrees depending on how much my speed is reduced from my combat speed.

    So, the shortest of all answers is the from a properly trimmed airplane, it is speed that affects trim and not attitude.

    Hope this answers you questions and feel free to ask away.

    Ramblin'jack
    Thanks, Jack. This is exactly what I am trying to get at. A good lesson. I got it now. Btw, I watched some video on ground attacking and ship attacks. They say it's no no to use rudder. Why is that? Ground attacks usually initiated by a dive. Wouldn't that offset trim and you add a bit left rudder to keep plane straight?

  6. #6

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    Oh, just another quick favor to ask. I have Saitek Pro flight rudder, but my rudder curve is really awkard. Anyone has the same rudder and a really good curve? (i.e. sensitivity setup ingame).

  7. #7

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    Pandacat - Can you be more specific or descriptive? What about your rudder settings are "awkward?"
    "If you love wealth more than liberty, the tranquility of servitude better than the animating contest of freedom, depart from us in peace. We ask not your counsel nor your arms. Crouch down and lick the hand that feeds you. May your chains rest lightly upon you and may posterity forget that you were our countrymen.”—Samuel Adams


    352ndFG - By the Community, For the Community...

  8. #8

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    Pandacat,

    I don't know why someone would indicate that you shouldn't use the rudder on a ground attack. I really like to fly aircraft that have the "ball" under the gun sight. Somewhere someone must have felt keeping the the ball centered was important enough that they placed the "slip - skid" indicator (i.e. the "ball") in clear view while using the gun sight. Whether or not you use the trim or rudder pedals to center the ball is immaterial. If you are lined up on a column of trucks and you fly down that line and the aircraft isn't properly coordinated (ball centered) you are likely to drop your bombs on either side of the line of targets.

    Keep in mind that I have never flown aircraft that are represented in this simulator and I have never shot at anyone or had anyone shoot at me. I have however strafed every outhouse and farmhouse in Nevada. Obviously without paying passengers and without real ammo. The thing that is true in both the sim and real aircraft is the fact that lining up for a ground attack you are looking outside the aircraft and using the rudders to keep the nose, (real) gun sight (sim) pointed at the target. Sometimes you have to "walk" the rudders to put bullets on target, but if you have lined up properly the only rudder pressure required is enough to center the ball. If you were trimmed before the dive you would have to add left rudder as the aircraft speed builds for the same reasons mentioned previously.

    I can't address your Saitek profile. I use CH rudder pedals and have them de-tuned because it is very easy to over control because you have no real feed back from the rudder pedals as you would have in a real airplane. Experiment and if you aren't, try flying with just a pair of socks on to get a feel for the pedals. I find that I can't fly with shoes, just can't feel the pedals.

    RJ
    Last edited by ramblin_jack; 08-20-2013 at 09:30 AM.


    "The most important branch of aviation is pursuit, which fights for and gains control of the air"
    U.S. Brigadier General William Mitchell

  9. #9

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    Quote Originally Posted by 352nd_Coster View Post
    Pandacat - Can you be more specific or descriptive? What about your rudder settings are "awkward?"
    Currently I have 60 60 60 70 70 70 100 100 100. On takeoff, I need step on right rudder all the way in order to keep plane in the center. In flight, it however feels too sensitive. So I am asking for some advice on setting up the curve.

  10. #10

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    Quote Originally Posted by pandacat View Post
    Currently I have 60 60 60 70 70 70 100 100 100. On takeoff, I need step on right rudder all the way in order to keep plane in the center. In flight, it however feels too sensitive. So I am asking for some advice on setting up the curve.
    I'll haven't had the opportunity to check, but IIRC mine are 50's across the board, for the sensitivity reasons RJ mentioned. I also cannot fly in shoes. Your control issue on take off can be solved in one of two ways. 1.) Line up on the centerline and lock the tail wheel or 2.) Do not exceed 50% throttle before your AC exceeds 60MPH. At 60MPH, the rudder becomes effective and you won't have the extreme control issues.
    "If you love wealth more than liberty, the tranquility of servitude better than the animating contest of freedom, depart from us in peace. We ask not your counsel nor your arms. Crouch down and lick the hand that feeds you. May your chains rest lightly upon you and may posterity forget that you were our countrymen.”—Samuel Adams


    352ndFG - By the Community, For the Community...

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