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I understand the basics on trim, but ... perhaps I just haven't found the right video?

 

If I'm flying and the plane is tending to want to climb (let's say a lot, like 20degrees), and I want to level out my flight, am I doing it wrong in thinking that you simply apply nose down trim until the plane is going roughly level, then adjust trim up and down to perfect it?

Also, for the people who have flown combat a lot: Is trim adjustment something you ever adjust in combat?  I'm mapping my x-box controller, and part of my philosophy on mapping is to try and keep non-critical functions on the keyboard or using minimal modifiers.   Is Trim something that is safe to put behind a modifier or two attached to the keyboard arrow keys or the numeric keypad?  Or am I going to get into average PVE missions and regret not having fast access to it?

 

Thanks

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That’s basically it in a nutshell, if the nose keeps climbing hands off, then nose trim down to stabilise. But be aware that you can only trim for the speed you are flying at that time, if you accelerate the nose will climb - conversely if you slow then the nose will tend to drop (depends on the aircraft).

As for in combat, I frequently trim a wing to counteract an imbalance (in most all aircraft) - say a store or missile has been fired singly, it’s twin is still there on the other wing, I will trim to counter the roll ONLY IF I don’t envisage using the other within the next 30-60 seconds.

It’s no fun trying to manoeuvre hard with an out of balance aircraft, why make it more difficult for yourself!??!

 

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Trim is different in all aircraft: the german props handle it differently from the american props, and the spitfire handles it differently from both the germans and american props. Those with an electronic flight control system uses computers to send signals to servos, which trim out the aircraft longitudinally (nose up and down)at any speed but not laterally (wings up or down). Trim in helicopters is even more different than that, so it really just depends on which aircraft you are referring to.

 

The gist - Propellers you would trim pitch and roll for certain speeds and prop pitch. Germans you would also have trim tabs on the wings, but no trim wheel for roll. US fighters have a trim wheel for both and rudders, and the Spitfires you have to trim rudder to trim roll and yaw. These are the fundamental aircraft you would learn how to properly trim an aircraft, and to trim helicopters is technically not so in-depth but theres a LOT to talk about to properly trim one of them things as they vary from helicopter to helicopter too. If you want to do minimal amounts of trim, just fly an FBW type aircraft like the F-15/F16 or any of the russian FC3 aircraft (not sure if they have FBW, but you trim them out the same as the F15/16).

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4 hours ago, G.J.S said:

That’s basically it in a nutshell, if the nose keeps climbing hands off, then nose trim down to stabilise. But be aware that you can only trim for the speed you are flying at that time, if you accelerate the nose will climb - conversely if you slow then the nose will tend to drop (depends on the aircraft).

As for in combat, I frequently trim a wing to counteract an imbalance (in most all aircraft) - say a store or missile has been fired singly, it’s twin is still there on the other wing, I will trim to counter the roll ONLY IF I don’t envisage using the other within the next 30-60 seconds.

It’s no fun trying to manoeuvre hard with an out of balance aircraft, why make it more difficult for yourself!??!

 

Thanks.  So essentially trim is, overall, not life-threatening critical to trim in the middle of a dog-fight unless you have a little time to adjust it.  And it makes sense to use it to adjust for drag.

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Posted (edited)
1 hour ago, NeuralBlankes said:

Thanks.  So essentially trim is, overall, not life-threatening critical to trim in the middle of a dog-fight unless you have a little time to adjust it.  And it makes sense to use it to adjust for drag.

 

That's what autopilot is for.  I use trim to get it to ball park.  After dropping ordinance from one side, it will pull and find myself having to put a lot of stick input to keep it straight.  That's when I use trim.

 

I think the answer you're looking for is if it's necessary to have it accessible.  And my opinion is yes.


Edited by Taz1004
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2 hours ago, Hammer1-1 said:

just fly an FBW type aircraft like the F-15/F16 or any of the russian FC3 aircraft (not sure if they have FBW, but you trim them out the same as the F15/16).

I wouldn't say they are anything alike. Russian birds need constant pitch trimming while F-15C just holds attitude all the time.

 

@NeuralBlankes The pilot flies mainly with the stick. If you want to hold attitude and you have to put force on the stick - it means you're not trimmed and have to trim to not put that force constantly. You'll get used to it and will do it automatically without thinking soon. If I see my nose climbing the first reaction is to put stick forward, only then I trim it nose down while letting the stick to center simultaneously. Most of the flight you should be trimmed so you don't have to do special trimming before the combat (BFM). Trimming during combat does not make sense if your stick is not centered and you constantly maneuver. Mind that if you're seriously out of trim before the combat you can deprive yourself of critical part of pitch range in some aircraft!

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Hi Neural.

Just remember what real life pilots says about the trim: "trim is your friend!" So keep it easy to reach and use, for normal/flight procedures, try to be alwas trimmed properly when in combat (non BFM/ACM), but for dogfight... I can't even think about it, just fight. Just follow  draconus advices.

Saludos.

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10 hours ago, NeuralBlankes said:

If I'm flying and the plane is tending to want to climb (let's say a lot, like 20degrees), and I want to level out my flight, am I doing it wrong in thinking that you simply apply nose down trim until the plane is going roughly level, then adjust trim up and down to perfect it?

 

You can do that, but it's neither what trim is supposed to do, nor is it good technique.

 

What pitch-trim actually does is control airspeed for a given amount of thrust.

 

Here is how it works (in a nutshell):

A given amount of thrust will yield a given amount of airspeed, where thrust = drag.

 

If you now trim to another airspeed but keep the thrust constant, the aircraft will seek this new speed - either by descending (trimmed nose down = wants to go faster) or by climbing (trimmed nose up = wants to go slower) - until it attains that trimmed speed at given (constant) thrust. This would normally result in a descent or a climb respectively, as thrust and airspeed are mismatched.

Now turn it around:

You keep the trim, but change the thrust - adding power will make the airplane climb and reducing power will make it descend. Both the climb and the descent will happen at trimmed airspeed. Same here: Thrust and airspeed are mismatched.

 

In the actual airplane, you're just trimming-out the control forces (stick displacement for most players).

This is true in pitch and roll, as well as in yaw (trimming to zero pedal force/ ball centered with the feet off the rudder-pedals).

 

Trimming is normally only used in relatively steady state flying. You would not trim much in aggressive maneuvering.

 

 

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Posted (edited)
7 hours ago, draconus said:

I wouldn't say they are anything alike. Russian birds need constant pitch trimming while F-15C just holds attitude all the time.

 

All I said was they trim the same way; IE you click the trim hat switch. All I meant with that statement.

 

A certain wise pilot once told me that you dont trim the aircrafts flight controls, you trim the aircrafts speed. Im not exactly sure how much of that statement is true, but it seems to hold some bit of truth to it. A truly trimmed aircraft flies straight and level at its current speed. Pick a speed and trim for that.


Edited by Hammer1-1

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Ok, I *think* I understand it now in general.

 

Just to verify, trim can be considered a compensation for drag and variances in drag while in flight.  Drag changes depending on the speed of the aircraft as well as other properties such as the distribution of ordinance on the wings, damage, etc.

 

At the  same time, if you're in a dog fight trying to avoid a Sidewinder, at least for a new person, you're not going to be adjusting the trim very often while in the middle of maneuvers as you are moving the control stick anyway.

 

Am I on the right course there?

 

(note: appreciate the help with this.  In the future I'd like to get a stick/thrust controller setup, but for now have keyboard and X-box controller.  Trim is on the keyboard arrow keys for now, which seems to work as physical position goes)

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Posted (edited)

Theres no need to adjust for trim in the middle of a fight, especially when rolling off of a target with a bomb load. You survive first, trim later. You trim when you got a minute to trim.


Edited by Hammer1-1
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There is an exception to that, though: German (and Italian, though we don't have any in DCS) WWII aircraft. They trim pitch by moving the entire tailplane, and this affects elevator authority. In a dogfight, trimming the tailplane can be helpful for squeezing just a little bit more performance out of those aircraft. Yes, you don't want to be in a dogfight in those birds, but either way, a properly trimmed tailplane will have both less drag and better authority.

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On 6/2/2021 at 1:23 PM, NeuralBlankes said:

Just to verify, trim can be considered a compensation for drag and variances in drag while in flight. 

Not just drag but lift and weight distribution as well. Changes in speed and altitude will effect how much lift the aircraft is generating, and necessitate a trim change. In the Tomcat changing the wing sweep will also change lift and you'll want to re-trim. Asymmetrical weapons loadout will make one side of the plane heavier than the other, which you can counteract with roll trim. 

 

Quote

At the  same time, if you're in a dog fight trying to avoid a Sidewinder, at least for a new person, you're not going to be adjusting the trim very often while in the middle of maneuvers as you are moving the control stick anyway.

Correct, trim is mostly something you would ignore in combat. Trim is most useful in straight and level flight, like cruising between waypoints, or when fine precise control of the aircraft is needed like when landing or conducting in-flight refueling. 

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As a commercial pilot with 3 decades of flying it pains me to see the answers about trim. A trimmed aircraft will fly itself. You pitch the aircraft to the attitude you want AND then trim it to ease the pressure on your control surfaces. It is impossible to fly an aircraft severely out of trim. That is why we set it prior to takeoff to a known value. 
 

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3 hours ago, Horse said:

As a commercial pilot with 3 decades of flying it pains me to see the answers about trim. A trimmed aircraft will fly itself.

 

I do try to trim to perfection in MSFS 2020.  Question was trimming during "combat".

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21 hours ago, Taz1004 said:

 

I do try to trim to perfection in MSFS 2020.  Question was trimming during "combat".

I’m not speaking perfection. Aerodynamics is the same no matter what phase of flight.  You can fight the aircraft or use the trim to assist.

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Again you dont trim in combat. To do that would be to invite disaster unless you have a serious malfunction somewhere, and your hands and head are too busy keeping yourself alive. Just trim when you got a chance.  Also, if you are thinking you can get a little bit more pull in one direction using trim, dont bother. Thats just something you will have to undo later, and that takes a lot of time to do.


Edited by Hammer1-1
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5 hours ago, Horse said:

I’m not speaking perfection. Aerodynamics is the same no matter what phase of flight.  You can fight the aircraft or use the trim to assist.

 

I didn't mean perfection literally and you're still missing the point.  You were talking about trimming until it flies itself and now you're saing just assist.  Which is actually what I and many others have said.

Did anyone here say don't use trim?  Which answer was painful to see?

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8 minutes ago, Taz1004 said:

 

I didn't mean perfection literally and you're still missing the point.  You were talking about trimming until it flies itself and now you're saing just assist.  Which is actually what I and many others have said.

Did anyone here say don't use trim?  Which answer was painful to see?

Hope your life cheers up. Adios.

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8 hours ago, Hammer1-1 said:

Again you dont trim in combat. To do that would be to invite disaster unless you have a serious malfunction somewhere, and your hands and head are too busy keeping yourself alive.

 

Not even pitch trim in a jet or rudder trim in a prop? There can be extreme speed and power changes during a dogfight that will throw the plane wildly out of trim. Are you speaking from first hand experience? 

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Referring to all human-piloted flight in the history of aviation: it depends. Most of the time trim is there for pilot comfort without a significant difference between holding an input and trimming or some combination of the two. But in certain conditions trimming can provide advantage or may even be necessary.

 

Usually the pilot puts in primary control input to perform the airplane as desired and then applies trim to reduce control pressure while holding the control input position. Real airplane controls and standard PC joystick behave totally differently. In real airplane I might have to push stick 1" forward and there is a force pushing back. I use trim to make force go away but stick remains in the same position. In DCS with typical controller instead you must relax spring joystick back to center after trimming. You push 1" forward, trim, and let stick come 1" back. It's different and so real life best practices may not apply.

 

Still, even with PC spring joystick it is commonly understood that "flying with trim" is a bad technique similar to real life. Trim is usually slower and less graceful than simply moving the controls to what is needed. Good technique with the primary controls will almost always produce better maneuvers than with the secondary (trim) controls. For relaxed flying with small trim adjustments especially in larger airplanes making small adjustments purely with trim can be good technique. It's also common to apply predicted trim changes simultaneously with primary control input when you can estimate trim needs after a maneuver (e.g. break turn into overhead landing pattern).

 

Trim has been used to get WWII planes out of dives but sometimes it is expressly directed not to use trim because trim forces can be higher than pilot input would produce. Sometimes it's not just pilot comfort that trim aids but his overall strength. Modern hydraulic controls this is not a problem but mechanical controls it can be.

 

You have controls which do not fully resemble the real airplane's so don't worry so much about real technique exactly. Most of the time the primary controls should be your first choice to maneuver with trim making those primary inputs comfortable once the airplane is maneuvering how you want it. PC pilots should be good at technique of changing trim and joystick deflection at the same time in opposite directions so that actual airplane controls do not move. Normally you trim for steady state conditions, long straight sections of fight and not for dynamic maneuvers. E.g. trim for the 10 mile landing approach but don't trim for the flare or landing. Ultimately trim is a tool to help you fly better and more comfortably but it should not be the first thing you interact with when maneuvering unless there is a good reason for it (i.e. you can't do what you need to do with only primary controls).

 

During a protracted combat sequence when you started fast with nose down trim and ended up slow with nose up trim, sure that is not against any rules. Trim can change when you have time to think about it but it doesn't have to be precise.

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Yet again about in-combat trim. Combat (even BFM) does not mean constant pulling on the stick. There are some gun solutions and strike runs where you want to use trim to stay steady and precise. And it's not true that it takes time or your attention. Unless you're a rookie you trim subconsciously without thinking about it.

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12 hours ago, Cab said:

Not even pitch trim in a jet or rudder trim in a prop? There can be extreme speed and power changes during a dogfight that will throw the plane wildly out of trim. Are you speaking from first hand experience? 

Before or after a bomb run definitely. During? Running in with an A-10 on a gun run? Yeah. How about during a dog fight? SAM Evasion? AAA? Are YOU going to think about trimming? I can understand trimming prop pitch for more power; I dont recall one instance where a fighter pilot of old had mentioned trimming his aircraft in the middle of a dogfight. Show me one instance and Ill eat my pound of crow.


Edited by Hammer1-1

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34 minutes ago, Hammer1-1 said:

Before or after a bomb run definitely. During? Running in with an A-10 on a gun run? Yeah. How about during a dog fight? SAM Evasion? AAA? Are YOU going to think about trimming? I can understand trimming prop pitch for more power; I dont recall one instance where a fighter pilot of old had mentioned trimming his aircraft in the middle of a dogfight. Show me one instance and Ill eat my pound of crow.

 

Personally, I don't think about trimming, I just do it. Increase power = couple of clicks (or three or four) of nose down trim; decrease power = same, but nose up trim. (Full disclosure, sometimes I forget). But that is in game only because I have never flown jets that way in real life. That's why I didn't give an opinion.

 

On the other hand, you offered a definitive declaration that trimming in combat would "invite disaster", so I just wanted to know what you based that on.

 

 

 

 

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34 minutes ago, Cab said:

Personally, I don't think about trimming, I just do it. Increase power = couple of clicks (or three or four) of nose down trim; decrease power = same, but nose up trim. (Full disclosure, sometimes I forget). But that is in game only because I have never flown jets that way in real life. That's why I didn't give an opinion.

 

On the other hand, you offered a definitive declaration that trimming in combat would "invite disaster", so I just wanted to know what you based that on.

 

 

 

 

Its a low priority item in the thought process. Survival always comes first, saving the aircraft always comes second. Trimming to keep your aircraft precise on a bomb run is a given, but in the heat of the moment its the last thing you should worry about until it IS the thing you need to worry about.


Edited by Hammer1-1

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