So, how do YOU trim your plane?

[Wildewinds]

Getting back into flying after a five year hiatus, I realize I don't have a very good sense of whether or not my plane is trimmed correctly. Is it nose heavy? Tail heavy? Is the camber or reflex doing what I want it to do?

So, any tips or tricks on how to trim?

[D_Ryan]

A volatile topic to be sure, certain to generate a number of diverse opinions... Nevertheless, two informative articles that are well-written can be found here:

http://www.badger.rchomepage.com/trim.html

and here:

http://www.gliders.dk/triming_and_setup_of_a_glider_wi_eng.htm

Credit to Warren Man-Son Hing and Erik Dahl Christensen respectively; hopefully they do not object to me providing these links.

r/
Dave

[SoCalGliderFlyr]

I keep taking nose weight out till it flys backwards then add a half ounce.

[BMatthews]

For basic CG placement I like dive testing. Tune the CG and resulting elevator trim until the model just slooooooooowly pulls out of a dive. That's about 3 steps before it starts flying backwards! ! ! ! ! :D

Good one Socal... LOL

[SoCalGliderFlyr]

:)

It's the truth! Well, those that have flown my planes say it is.

[thelocust]

1. Ensure all physical trims on the ground are in good order. Elevator flat (full-flying ones are tricky), rudder straight, ailerons and flaps good.

2. Fly it fast - this will give you a good indication of any trim issues. This also includes doing a dive-test which will get you up to that high speed. If the plane pulls up when speeding up, you are nose-heavy.

3. Fly it slow -- see what thermal camber and landing flaps do to it while you have altitude.

4. For a poly plane, see how long it takes for you to initiate a turn with the rudder. This can give a good indication of not only rudder throw but proper washout/in on your tips.

This is assuming that your wing and tail are square and that your linkages are tight.

That's what I've done on handlaunch, 2-meter and unlimited ships. That said, I still have plenty to learn!

[histarter]

1. Ensure all physical trims on the ground are in good order. Elevator flat (full-flying ones are tricky), rudder straight, ailerons and flaps good.

2. Fly it fast - this will give you a good indication of any trim issues. This also includes doing a dive-test which will get you up to that high speed. If the plane pulls up when speeding up, you are nose-heavy.

3. Fly it slow -- see what thermal camber and landing flaps do to it while you have altitude.

4. For a poly plane, see how long it takes for you to initiate a turn with the rudder. This can give a good indication of not only rudder throw but proper washout/in on your tips.

This is assuming that your wing and tail are square and that your linkages are tight.

That's what I've done on handlaunch, 2-meter and unlimited ships. That said, I still have plenty to learn!
Succinct and accurate. Airspeed is the key. :) If you trim CG for slow flight (to work light lift as prime interest), your machine will be nose heavy at lower alpha for zipping across the sky - with the converse true but showing up as tail heavy when trying to float at high alpha. [With CG back for performance, I tended to land hot; whereas, with my light air machines I could 'creep' onto the spot.] :D

[BMatthews]

Histarter, I think you have the right idea but perhaps expressed it wrong. CG setting is not really speed dependent and should not be set that way. What the CG position gives you is more or less pitch stability. Some pitch stability is a good thing but too much results in strong trim changes as the speed varies as you've mentioned. But too much makes it more work to fly the plane. And as noted the more to the rear the higher the performance but that performance should not affect the flying speed or ability to trim the glide unless there are design issues.