Aircraft Trim

[hinch]

I am enjoying my foray into FSX but I'm having a really hard time trimming aircraft - it doesn't really matter what plane but they love to swoop up or dive down as soon as i get a click in. I use trim on the keyboard and on the stick but neither makes a difference.

Any hints about making my aircraft more stable? I have turned sensitivity right down but I still find it super hard to fly level.

[IanP]

Move the sliders on the trim "repeat" commands to about half. Any more than that is totally unrealistic and you won't be able to trim because the changes are too great.

Cheers,

Ian P.

[azflyboy]

Just find a setting that's comfortable for you, and stick with it. Depending on the aircraft you're flying, you can also alter the aircraft.cfg and change the trim effectiveness if it's way too touchy or does nothing whatsoever.

I think part of the problem is that FSX does a pretty poor job of modeling trim systems, since it simulates elevator trim by actually shifting the CG of the aircraft around to make the nose go the appropriate direction.

In the 172's I fly in the real world, I can trim for pretty much hands-off level flight within a couple of seconds, but in FSX, it takes a lot longer, since there isn't the same feedback.

Also, real world airplanes are trimmed for a specific airspeed. For example, if a Cessna is flying level at 100kts and is trimmed to fly hands-off, it will always seek that airspeed. If the power is reduced, the airplane will settle into a decent at 100kts, even if the pilot doesn't touch the yoke.

FSX doesn't seem to quite work this way for some reason, but I haven't figured out exactly why as of yet.

[fliger747]

Not all real aircraft are totally speed stable with power change! Several effects here, the most common being in single engine prop aircraft, the change in stabilizer downforce with propwash. In many aircraft with non verticle centerline thrust significant pitch change also results from power change. In the Boeings with pod mounted engines more power gives pitch up, less power, pitch down. in the Lake amphibian, add power and a serious nose down pitch insues.

I hadn't noticed that the CG changes with pitch trim. Easy enough to check this out with AFSD by running the pitch trim. I'll report back on this....

T.

[fliger747]

Tried an experiment with the default FSX C-172... Ran the pitch trim up and down while on the ground. CG remained the same at 14.88% MAC.

To my knowledge trim in FS works the same as the elevator in adjusting the pitch moment of the wing.

T.