What's Up With Takeoff Trim?

[Widewing]

When I spawn a P-47 with auto-takeoff enabled, trim is at full up elevator, about 30% right rudder and about 50% aileron to the right. Trim changes the second you add power, with the elevator going to neutral and aileron going full right (on the indicator), If you chop power during the roll, aileron trim shifts to full left.

If I disengage auto-takeoff immediately after spawning, the trim stays as set when spawning.

I manually set elevator to neutral, aileron to neutral and kept rudder trim where it was. Takeoff required a bit of rudder to counter torque and the takeoff run was routine. No hint of trouble, no cross-controlling was required.

I suggest letting the P-47 fly herself off the runway. No need to rotate, per se. If you rotate too soon, the increase in angle of attack can cause a stall, with resulting wing drop. Let the Jug fly off by herself...

You can always ease the stick back as you begin the takeoff roll, which will lock the tailwheel and minimize torque drift.

My regards,

Widewing

[Ack-Ack]

Originally posted by Benny Moore
You mean with auto-trim on, or off?

Whether with any of the auto trims enabled or manual trim, if your joystick is properly calibrated there is no need to adjust the trim dials on the stick.  Trimming your stick only trims the potentiometers in the stick and isn't a very good idea to use them to trim the plane you fly in the game.


ack-ack

[Benny Moore]

When flying the P-38, that is perhaps true.  However, when flying something like an Me-109, it becomes literally impossible to control the roll at certain speeds without trimming.  Moreover, one's hand tends to get a bit tired (although gaming joysticks obviously don't have significant stick forces) holding the stick off to one side.  In my case, I just had hand surgury and my other hand needs it so I am taking every precaution to avoid stressing both of them.

Another reason for trimming your airplane at all times in game is joystick life.  I use CH, and I love them for precision, but they are terrible about durability.  Roughly once a year, either my joystick or pedals begin to malfunction.  It seems that constantly holding the stick or pedals in a certain position aggrevates the problem, bringing early failure of the potentiometers.  The first sign of failure is usually a button not working when the joystick is held in its usual off-center position.  For instance, in the P-38, since I usually fly at about three hundred miles per hour indicated, if I never touch the trim I must hold the joystick forward several inches in order to stay level.

On the other hand, trimming the airplane in the game changes the "feel" of it when turning, causing me to sometimes stall when I never would have at the default trim.  I'm currently debating whether to go back to my usual untrimmed state or continue trimming after my hands are fully healed.  Both have their benefits.

[edit]Oh, I just reviewed your last two posts and your meaning became clear.  I'm sorry, I thought that you were talking about trim in the game, the simulated software trim (either bound to a slider or keys).  I agree with you fully that there is no reason to use the physical trimmers for your gaming joystick, whether they affect the potentiometers or, like mine, simply the physical center of the gaming joystick.[/edit]

[bozon]

Originally posted by Stoney74
My question is basically that if a plane is taking off in a cross-coordinated condition, the takeoff roll is going to be much longer than it needs to be.  I just don't understand why you would put in all that right aileron trim and then have to counteract it with LEFT rudder trim on takeoff.
 

You need a lot of right ailron trim because of the huge torque. And by torque, I mean on the roll axis. At low speeds the ailrons are not effective and so you need a large deflection. On the other hand you are operating at full power and generating as much torque and the engine+prop can give.

If you don't trim roll-right than as the wheels start to get off the ground you'll violently roll to the left.

The rudder trim is not to correct for the uneven drag of the ailrons, this is a weaker secondary effect. The main issue is prop-wash hitting the tail and causing yaw force and some P-factor when you pick up speed.

I don't know how it works in AH, but some planes have a small bias angle in the tail, so neutral trim and rudder is still not zero AoA in perfect airflow and may produce any kind of yaw depending on the bias and flight conditions. It doesn't really matter, the only point of rudder use in coordianted flight is to keep the nose directed into the airflow. In a single prop plane it ALWAYS means that the tail produces some lift(yaw)+drag+secondary roll force.

Some inefficiency is built into this single prop configuration which you cannot avoid. A hellicopter is a much more extreme example of severe inefficiency caused by torque effects.

[Schatzi]

Originally posted by bozon

If you don't trim roll-right than as the wheels start to get off the ground you'll violently roll to the left.

You can get a feel for that effect when taking off a non-trimmed D-Hog with CT off.

[Rolex]

I understand take-off trim for the F4U was:

6 degrees rght aileron
6 degrees right rudder
1 degree up elevator

Using Combat Trim, trim on the F4U is the same on landing as it is on take off, which contributes to the squirreliness on touchdown. If manifold pressure was also a parameter, not just speed, it would be closer to a full "auto-trim" system.

That's easy for me to say, since I'm not the one doing the programming...

I think the name "Combat Trim" is appropriate and reasonable for what it is designed to do. The average new (or older) player wouldn't have much of a chance at getting a real F4U, or P-47 in the air anyway.

[The Fugitive]

Originally posted by Benny Moore

Another reason for trimming your airplane at all times in game is joystick life.  I use CH, and I love them for precision, but they are terrible about durability.  Roughly once a year, either my joystick or pedals begin to malfunction.  It seems that constantly holding the stick or pedals in a certain position aggrevates the problem, bringing early failure of the potentiometers.  

You must have gotten a really bad set of CH stuff !! I've just recently gotten a new CH stick and throttle, because the prior set I had no longer worked with my new motherboard. The old set was over 5 years old, and I had bought them used on Ebay, so who knows how old they were. The only reason I changed, was the newer MBs don't supply enough voltge thru the keyboard plug to run the buttons on the stick and throttle with the analoge setup. I still use the Analoge pedals whish are over 5 years old and need calibrating now and then, but other than that no trouble.

As for triming, the sliders in the controller setup are to adjust how your stick is tied to the game...IE: some like very quick responce, other want slow ponderis movement, that is where you adjust it.

The keyboard trim buttons are used to add trim deflection to a control surface. These can be seen on the dashboard in the planes as a line that moves in the red boxes. A "trick" to using "manual" trim with out having to play with the buttons all the time is to flick the combat trim on then off again. This will trim the plane for that speed and attitude. So, if you get the plane flying level at your "attack" altitude, flick the combat trim on and off and the plane will trim for level flight....no need for forward pressure on the stick, or elevator left of right to keep it level. You must be at a constant speed to do this because it will change your trim setting if your speed increases, or decreases.

[stantond]

I have a USB Fighterstick that had the 8 way view hat switch give out, which was replaced, then a roll axis pot go bad.  I have yet to replace/repair the roll axis pot and have been using the 'backup' USB Fighterstick which has worked without any problems so far (>1 year).  Since these switches and pots cost about $2-3 a piece, their lifespan varies depening on which lot was made.  I am quite confident that real military aircraft, which have an identical looking stick and switches, have much higher quality control parts (and cost much more).  Sometimes it's just the "luck of the draw" getting a really good, or not so good, CH stick.

Regarding take off trim, try flying the C47 without auto take off using combat trim!  It's a real challenge and fun too (if you like that sort of thing)!  One thing about combat trim is that it changes based on your speed which means it varies.  I too like to set the trim settings based on pilot manuals.  While it's cool to do this, it adds little to the game (imo).   I will mention that when landing planes that need to have the tail wheel locked, not using combat trim   makes landing easier.




Regards,

Malta

[Stoney74]

Okay, I've managed to figure out how to setup the non-combat trimmed, non-auto takeoff.

Now, my only question is whether or not someone can explain what part of the flight model causes the condition displayed in the first screenshot I posted above when auto-takeoff is used.

???

[Golfer]

instant reactions to the flight model far and away beyond the capablities of a human to process.

[Auger]

Originally posted by stantond
Regarding take off trim, try flying the C47 without auto take off using combat trim!  It's a real challenge and fun too (if you like that sort of thing)!  

I never use auto take-off, but I'll have to try rolling a C-47 with combat trim on.  It's pretty squirrelly after the first 10 seconds until it gets up to about 75 KIAS.  I have to adjust my view with Page Up to see where it's going and use lots of rudder to keep it on the runway.  It likes to do the tail wheel slide on landing too.  Wonder if combat trim will compensate for that....

[bj229r]

N tries to do  does wicked counterclockwise ground loop around 80-100 mph--(before tailwheel leaves ground) I dont do autotakeoff,  but if ya hit 'autopilot' around then, the trim cant compensate enough to keep plane on runway

[Tigger29]

Yes you have to realize.. the auto take off that is controlling your plane is probably constantly making changes not only in trim, but in direct input to the controls as well.  It is also reacting much faster than any human could possibly try to recreate, and it's not necessarily going to be reflected in the trim settings shown on your display.

I've flown single engine Cessnas in real life, and all kinds of aircraft in several simulators.. and assuming that AHII is "physically" realistic, I've noticed the the torque factor is much more prevalent here due to the fact that these planes are for the most part, very high performance aircraft!

If I tried to fly these things like I do a cessna, I'd never leave the runway without certain death.  Whether historically accurate or not, I simply try to get off the runway as quickly as possible, and that means forgetting about trim, and using direct inputs to keep the plane straight on the runway, and level during take off.  I don't even mess with trim until I'm in the air, and I rely heavily on auto-takeoff and auto-speed (unless I'm in a simulating mood).

Simply put... start engines... full throttle... use rudder and ailerons to keep control until I'm in the air... auto-level to get my speed up then climb up.  A lot of the time the base is at least partially porked and I simply do not have time to do it smooth and straight, because alot of the time I'm performing evasive maneuvers before I even get into the air.

To me the thrill is the challenge in getting around the enemies and then trying to blow them up.  When I'm in the mood for realistic flying, such as following procedures, checklists, etc... I'll go play MS Flight Simulator.

[Iceman24]

pull back on the stick, the harder you pull the more it locks the tail wheel in place, tailwheel only aircraft

[Golfer]

if i pull back on the stick really hard will it lock the tail wheel so much that the canopy locks too?