View Full Version : Elevator Trim???

11-11-2007, 07:05 AM
I have my elevator trim mapped to the right-side rotor on my X52's throttle control. The problem is that on nearly every aircraft I fly, I have to trim the nose down, or I will go into a steady climb. The climb angle is about 10(+-) degrees. When I look at the elevator it is aligned flat with the HS. After I trim to make the airplane to fly level, it is pointing down about 10 degress. This is consistant on every flight, all flight speeds and varies very little between aircraft types. I would think that that much trim would effect speed. It seems to effect dive recovery and other things. I find myself constantly making adjustments.

At first I thought this was an X52 problem, but the fact that I can see the elevator position tells me its something else.

11-11-2007, 08:35 AM
umm, gotta say my experience of trim (on a rotary) in fb is a little different in that there is a speed at which zero elevator trim can fly the plane level, above this speed down trim is required in a fairly linear relation to speed over this 'level flight' speed and requires progressively more up trim as speed reduces. for most piston engined fighters this speed is somewhere around 270-300 kmh.

are you 'testing' this at full throttle? try reducing throttle to maintain speed at say 300 kph THEN trim to maintain level flight- ie your vertical speed indicator shows no climb/dive. allow things a little time to settle and then make fine adjustments to attitude/trim/power.

you say you are constantly making adjustments, this indicates to me you havent 'played' with the input curve of your rotary and as such its response is like a joystick set to 100% across the board- ie very sensitive. maybe a utility like il2-sticks is worth looking at?

try a linear 'curve' going from 0 to 100% at first or maybe flat at 50% to start - then adjust to what works for you (personally i use a line going from 20-60 http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif )

i'm assuming your stick is correctly calibrated in windows?

hope this helps

11-11-2007, 02:51 PM
If you fly aircraft at full throttle, near top speed, then a down-trim is the thing you would expect needed for level flight.Doing so is making yourself vulnerable. At high speed your plane will be less maneuvreable. Do you drive through towns with the pedal to the metal too? (just an example from R/L) Trim is valid for one altitude+speed combination. If either changes you need to re-trim for level flight at that alt+speed. The best speed to keep depends on the plane, altitude and mission objective (long range flight, intercept,dogfight etc).

11-11-2007, 04:29 PM
Found some old posts on this topic (shoud have looked there first). In my limited expeince at the controls of small aircraft some 40 plus years ago, I don't recall having to trim for speed but rather for wind and loading.

Thanks All.

11-11-2007, 04:44 PM
well, IL-2 is not real life - lucky us. That said, you would not fly full throttle in real life either. If you did you would get an extra up force too - Just think of the phugoid motion which btw is modeled in il-2 also http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif All in all the FM in il-2 is superbly modeled. Due to the number of planes that can be in the air at one time there are limits and simplifications as there are in all simulators. Even those costing multi millions of $ in use by the military and commercial airlines.
I'm not saying you should fiddle with trim constantly, just adjust it when needed to solve any problems with attitude of the plane. I don't think you should compare a powerfull warbird to an underpowered antique private plane. There are big differences.

11-11-2007, 07:35 PM
Here are USAF ace Bud Anderson's comments on constantly trimming the P-51:

"A lot of this is just instinct now. Things are happening too fast to think everything out. You steer with your right hand and feet. The right hand also triggers the guns. With your left, you work the throttle, and keep the airplane in trim, which is easier to do than describe.

Any airplane with a single propeller produces torque. The more horsepower you have, the more the prop will pull you off to one side. The Mustangs I flew used a 12-cylinder Packard Merlin engine that displaced 1,649 cubic inches. That is 10 times the size of the engine that powers an Indy car. It developed power enough that you never applied full power sitting still on the ground because it would pull the plane's tail up off the runway and the propeller would chew up the concrete. With so much power, you were continually making minor adjustments on the controls to keep the Mustang and its wing-mounted guns pointed straight.

There were three little palm-sized wheels you had to keep fiddling with. They trimmed you up for hands-off level flight. One was for the little trim tab on the tail's rudder, the vertical slab which moves the plane left or right. Another adjusted the tab on the tail's horizontal elevators that raise or lower the nose and help reduce the force you had to apply for hard turning. The third was for aileron trim, to keep your wings level, although you didn't have to fuss much with that one. Your left hand was down there a lot if you were changing speeds, as in combat . . . while at the same time you were making minor adjustments with your feet on the rudder pedals and your hand on the stick. At first it was awkward. But, with experience, it was something you did without thinking, like driving a car and twirling the radio dial.

It's a little unnerving to think about how many things you have to deal with all at once to fly combat."

11-12-2007, 10:22 AM
Great quote, Berg, thank you! http://forums.ubi.com/images/smilies/25.gif


11-13-2007, 06:09 AM
I also wasn't too happy with the trim so I used the mouse wheel on the front of the throttle. It turns out that each tiny "click" generated by it is mapped to a single key hit (unlike regular mice that generate 3) - so this gives you very fine tuning just as if you were using a keyboard.
I used the other two rotor axis for rudder and ailerons trimming and set their sensitivity quite low and filtering quite high using the IL-2 JoyControl tool.

11-14-2007, 06:59 AM
The setup I'm using now works fine now that I understand it.

I use the mouse wheel on the throttle for manually operating the landing gear. It has come in handy a couple of times when the gear mechanism has been damaged and when flying planes that have manual gear.

12-02-2007, 04:04 PM
I are having similary problems. I use standard joystick settings and are having trouble to level up my plane with confort let's say.

I constantly need to make adjusts to keep the aircraft level up, because she got some tendency to stay negative or positive.

wat I think I need is make the controls stay more heavier (hear a LW pilot in a interview say the BF-109 had tendency to yes, level up if the pilot was not mess up with the controls). I feel the controls very sensitive in this case. and, sometimes the plane fall 30 meters if a take my eye out of the airspeed indicator for some seconds. I think this is a very high value and should not be acceptable.

please, wat section I should adjust to make the controls stay more 'heavier' ?