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View Full Version : What is trim, and how do you control it?



Baltar
06-24-2004, 11:49 AM
Can someone explain to me exactly what trim is how to set up an X45 to manage it? Thanks.

Baltar
06-24-2004, 11:49 AM
Can someone explain to me exactly what trim is how to set up an X45 to manage it? Thanks.

BennyMoore
06-24-2004, 12:00 PM
The trim tab is a small control surface on a larger control surface such as an elevator. It allows you to set the larger control surface to a particular angle so that you don't have to constantly put pressure on the stick or yoke.

Trim is pretty much unnecessary in the game, because it takes no effort to hold your joystick in any position. However, in real life, your arm gets very, very tired trying to hold that yoke back three inches while you climb to five thousand feet (you are fighting the airflow, because when you're holding back the yoke or stick, the elevator, which is directly linked to the yoke or stick, is being held by you directly into the airflow). Therefore, you slide the trim wheel until it no longer takes effort to hold the yoke back.

You are not to use the trim to change your plane's attitude; you use the yoke or stick to do that, then while holding it there you trim out the aircraft until your arm isn't having difficulty. In the game, on the rare occasions that I use trim (long straight and level flights), I do the same thing as closely to real life as possible. Instead of merely applying down trim to the elevator until my plane is flying level, I hold the joystick at the desired angle and slowly center it as I press the down trim key.

Some people assign trim to a slider, because in real life the trim control is a wheel very much like an oversized slider, but I find this extremely unrealistic because in real life, switching from no trim to full trim takes quite some time. In the game, however, if you assign trim to a slider, you can do the same thing in no time at all by simply slamming your slider up or down.

Now, I'm not sure if World War Two aircraft had rudder trim and aileron trim, like the game does, but I know that a Cessna only has elevator trim.

-HH- Beebop
06-24-2004, 01:25 PM
On my X-45 I set the trim to the small forward rotary.
To set up, turn rotary knob all the way to the left (as your facing the throttle quadrant), open 'Controls', scroll down to 'HOTAS'. Click 'Elevator Trim', turn rotary all the way to the right. The assignment should read "X-Axis Rotation" If the trim works opposite of what you intended reverse the rotary rotaion and repeat above.

I've found that the trim responds rather realisticly based on my limited real life experiences flying civilian aircraft.

I've set my prop pitch to the large rotary. I find this very useful when flying German a/c with manual prop pitch.

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F19_Ob
06-24-2004, 01:32 PM
The most Important trim is the elevatortrim and this is used frequently during different stages of the flight, even combat.
Easily put, the elevator trim alows u to fly level in all speeds without the nose rising, wich makes flying more relaxed and precise.

After takeoff U will notice that the nose will rise as speed increases, this is where u start trimming it to stay level. When U slow down the nose will drop, then trim it up.


In combat its very important to have the elevator in correct trim because if the nose keeps rising when u are about to fire then u have to push stick forward and will mostly miss as u are unstable. Its generally better to have the nose downtrimmed a bit too much than up. This way u will be steadier. I mention this because u always doesnt have time to trim perfectly.

Some earlier planes had no trim (I-16 for example).And others had rudder, aileron aswell as elevatortrim. And yet others had trims that only were adjustable by groundcrew (on ground)


This was a quickie , but covers enough to get U started. http://ubbxforums.ubi.com/images/smiley/16x16_smiley-wink.gif

Taylortony
06-24-2004, 02:12 PM
I have read all the posts but none have them have really explained why you need to trim an aircraft so i thought i would add a word or two for your help..

Ok Elevator trim
When you aircraft takes off and is trimmed initially for level flight it is in perfect balance and no trimming is needed, but as you burn fuel the front of the aircraft gets lighter and the tail heavier there for you need to give it a little trim to reduce the forces needed on the elevator control, Imagine the tail is getting heavier, therefore you need to push the stick forward to increase the lift on the tail to compensate... doing this means you are pushing against the airflow... turning your trim raises a little tab on the trailing edge that forces the elevator down slightly and allows it to fly tail edge down and relieves the forces of you having to do it.

Aileron trim

no aircraft can be built perfectly balanced so this will lift or drop a wing so both are producing the same lift, by flying one aileron up or down to level the wing, this will also compensate for different power settings torque from the engine will increase or decrease roll.

Rudder trim

As said no plane is built perfectly straight so this will compensate for yaw which is the plane slewing in flight, it is also used on twins to relieve rudder loads if you lose one engine due to the thrust pulling on one wing greater than the other................ rudder will correct rolling motions too as the secondary effect of yaw is rolling...........imagine a plane yawing one wing will advance the other is retreating so the advancing wing is going faster and hence producing more lift to the aircraft rolls, putting in a bit of opposite rudder trim corrects this and levels the wings...........

hope that helps

Dubow
06-24-2004, 02:32 PM
Well, trim is something that if you're not getting any, it creates a lot of tension and frustration. So, that's why males tend to take matters into their own hands(literally)to quell those frustrations.

<S>
Dubow

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Baltar
06-24-2004, 02:59 PM
I take it then trim is supposed to have positive and negative values as well as a neutral state? It'd be nice if this could be done with the pinkie switch and using the joystick for the corresponding elevator or aileron trim level, and use the rocker switch for rudder trim. Can't seem to set it that way though...

LStarosta
06-24-2004, 03:01 PM
I wouldn't say trim is unnecessary, because it is, especially in combat. Trying to shoot straight while constantly pushing down on the stick cuz elevator trim's set too high is not a good thing to do. I will agree that it's much easier to deal with trim, or lack thereof, on a PC than in a real airplane.

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horseback
06-24-2004, 03:35 PM
Baltar-

As has been said before, elevator trim is useful in almost all types of a/c flown in FB, and you have trim assignments in the Control menu for both nose high and nose low trim. Elevator trim settings change with your speed; the faster you go, the more your nose tends to go up, and the more nose-down trim you need to fly level without a lot of extra stick pressure. Conversely, as you slow down, the nose tends to drop, and you need to apply nose-up trim.

In the game, there is a bit of delay in the effect of trim inputs; that is, when you push the keys assigned to positive or negative trim, it takes a couple of seconds to take effect, and so it's just a little harder to achieve good trim.

The next most important trim setting in the game is rudder trim; you can apply left or right trim to offset the torque of your engine on most Allied fighters (the makers of the 109 and 190, which were designed to be flown by ubermenschen, considered this an unnecessary extra weight penalty to accomodate effete pilots with weak thighs). The more power you apply, the more torque the engine generates, and the more rudder trim applied to counteract it. Again, if applied to an axis, you start at a center point. If applied to keyboard or joystick buttons, you will need to assign left and right trim.

Finally, there are some aircraft which feature aileron trim to further counter engine torque. This would also increase with the throttle setting and requires two buttons or keys or a centered axis.

I have a CH HOTAS setup, which allows me to choose between a POV hat on the stick and one on the throttle. The stick hat is harder to reach, and I have reassigned it to elevator trim and rudder trim on its cardinal (N--S, E--W) points, and use the throttle hat as the POV. I'm not familiar with the X45, but I seem to remember it having a couple of hat switches-you might want to keep the most convenient for POV, and use the other for elevator & rudder trim.

cheers

horseback

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LoneStarBuckeye
06-24-2004, 04:01 PM
I have a CH HOTAS, as well. I've programmed mine so that when I press a button, the trim inputs follow stick deflection. That is, when I press the "nose trim" button, nose down trim is fed in while the joystick is deflected forward and nose up trim is fed in while the joystick is deflected backward.

Bearcat99
06-24-2004, 06:16 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Baltar:
I take it then trim is supposed to have positive and negative values as well as a neutral state? It'd be nice if this could be done with the pinkie switch and using the joystick for the corresponding elevator or aileron trim level, and use the rocker switch for rudder trim. Can't seem to set it that way though...<HR></BLOCKQUOTE>

Baltar you already have one of the best means of controling trim...and prop pitch for that matter. I used to put my prop pitch on the throttle lever of my MSFFB and i had elevator trim on the thumb knob of my X45 and Aileron trim on the finger knob. I have since removed aileron trim from the finger wheel and put elevator trim there and put my pitch on the thumb wheel. The best way for you to understand trim is to set it up and use it. FB is ther type of sim that you can only do so much with advice. The best way for you to understand these concepts and how to implement them is to fly and use them.

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heywooood
06-24-2004, 07:57 PM
put it on a slider

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Dawg-of-death
06-24-2004, 08:03 PM
Let me get RBJ.
The slider is an option............. http://ubbxforums.ubi.com/images/smiley/59.gif



Bad-MF(Mongrel Fighter) AKA .......Dawg-of-death

WTE_Galway
06-24-2004, 08:05 PM
trim is critical for shooting especially if you have modified the joystick sensitivites


there i slittle point softening the centre of the stick formore shooting control if the aircraft is trimmed so that the stick has to be pushed forward into what is the sensitive part of its range

_VR_ScorpionWorm
06-24-2004, 08:05 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by heywooood:
put it on a slider

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<HR></BLOCKQUOTE>

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Well all info is above, I use elevator trim on the thumb rotary, and rudder trim on my arrow keys(only a little rudder trim is necessary), I dont bother with aileron trim. Just to add I have the index rotary mapped as prop pitch.

If your intersted in trimming the HE while bombing check out the "HE111 trim" thread with my post. http://ubbxforums.ubi.com/infopop/emoticons/icon_cool.gif

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MrCheesy
06-24-2004, 11:56 PM
Just one more thing that I didnt see mentioned, if you assign trim to the keyboard quite a few presses in the appropriate direction may be needed for any noticable difference, this varies considerably from plane to plane.

F19_Ob
06-25-2004, 04:19 AM
I have elevatortrim assigned to 2 buttons on my stick. I generally prefer my planes to be a bit downtrimmed so I'm always ready for combat wich can happen quickly. Although pressing buttons take a bit more time than having it on a slider, I dont have any problems with it...
A slider would be handy and more realistic.

Tully__
06-25-2004, 06:22 AM
All aircraft have one thing in common. At only one power setting will they fly level without any control input. At any other power settings, they will either climb, dive or require control input to fly level.

If you're in cruise flight (at cruise altitude and many miles from your destination), the first two are obviously undesirable and the third tires the pilot out.

To ease the load on the piot, trim tabs were invented. They are small tabs on the trailing edge of primary control surfaces that can be adjusted in angle. The angle determines the "at rest" position of the control surface (and the speed/power setting at which the plane flies straight & level).

The cockpit trim controls allow you to adjust the angle during the course of a flight. You may for instance encounter and unexpected headwind and need to increase your cruise power/speed to compensate. This will cause the plane to climb without a change in trim or constant pushing on the stick.

Trim is not intended for heavy manouvering, but to ease pilot load during long constant flight regimes (cruise, climb from takeoff to altitude or descent from altitude to landing approach). Some aircraft are equipped with trim on all primary controls, some on elevator only & some have no inflight trim at all.

If you'd like to do more reading on trim, Andy Bush's article (http://www.simhq.com/_air/air_003a.html) at SimHQ is a good read.

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Taylortony
06-25-2004, 11:20 AM
[QUOTE]Originally posted by Tully__:
All aircraft have one thing in common. At only one power setting will they fly level without any control input.[QUOTE}

Not totally true Tully, in a perfect world that would be the case but often you need to spend a lot of time initially to set an real aircraft up... on some you rig a control surface to fly down a bit etc to correct it without trim initially, some aircraft like Cessna actually have a concentric bush on the read spar attachment ( offset hole) and you drop or raise a wing trailing edge to get it level The cockpit trim controls allow you to adjust the angle during the course of a flight.

To ease the load on the pilot, trim tabs were invented.

Originally they never used trim tabs, as in the Spitfire Aileron, what they used to do was glue a section of cord hanging over the trailing edge of the aileron on the wing flying low, this had the effect of weighting the trailing edge of the aileron so as to droop it slightly and lift the offending wing into the level, this was adjusted to set it up with a pair of scissors and a section was cut off to fine tune the setting or "TRIMMED" off to be more correct and hence the term "To Trim the Aircraft"

Tully__
06-25-2004, 11:49 AM
Perhaps I should have prefaced that first statement with "In a given state of trim...."

Incidentally, boats are trimmed too, usually by moving cargo or ballast about in displacement hulls, but in inboard engined planing hulls there are often trim plates on the stern and outboards have adjustable driveline angles.

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Taylortony
06-25-2004, 01:44 PM
The likes of the B1-B "Bones" as it goes swing wing mode, it shoves fuel for and aft to trim it, early on in its development they lost one because the automatic system was turned off and as they swung the wing it dived in at low level...http://ubbxforums.ubi.com/infopop/emoticons/icon_frown.gif