What throttle level do most of you trim your plane for level flight. I have an LT-40 with a TT-46 and find that I don't have the throttle set constant for too long. It seems that I spend very little time at full throttle when flying level, so I don't know if that is a good setting to trim it level. Do the experts constantly trim a model during the flight?

For normal flying, you should trim your plane to fly level at about 1/2 throttle. Of course, everyone has a different flying style. For a trainer, cruising around at half throttle is about right. (Plus, you don't burn your expensive fuel up as fast)

A plane is USUALLY trimmed at ABOUT 1/2 throttle....... the throttle setting where you do the majority of your flying.

You should not have to constantly adjust the trim settings.

Once the trims are set, about the only time you MIGHT change them would be if there is more wind than usual.

I guess it's a personal thing. I set mine where the airplane feels like it has a comfortable "cruise" speed. Usually about 3/4 throttle, maybe a little more or less, depending on the aircraft. With the LT40 probably about 1/2 to 3/4 throttle. What speed do you most feel comfortable flying it? That's a good spot to start. You can always change it later as your experience grows.

If the airplane is built straight.... the only trim that should need adjustment with throttle is elevator. We don't fly straingt lines long enough for a minor aileron or rudder deviation with speed to be worth adjusting the trim.

Elevator trim can also need adjustment with fuel burn-off... due to the CG slowly moving rearward.

The need for retrimming with speed change is why I prefer the old analog trim sliders over the modern computer radio pushbuttons. You can learn where the trim sliders need to be for different flight conditions an quickly make the adjustments. I'm constantly retrimming any airplane as I change what I am doing with it.

Full scale aircraft... the pilot retrims for what he is doing with the aircraft. they learn that the plane neds X turns (or X "clicks") of the trim to go from 60 mph putting around to 120 mph cruise.

Thanks for all the responces. I will look for a comfortable flying speed the next time out and trim to that.

FH is right about full scale, but I trim my planes to fly straight and level at a particualr throttle setting (a comfortable cruise), and then fly. I have become accustomed to holding a bit of down, or up, or whatever to keep the plane flying as I want it to. I almost never retrim the plane for throttle changes, and NEVER for wind conditions. (If the plane is trimmed to fly straight and level, then trim changes for wind don't make sense; you'd have to trim for downwind flight, then retrim for upwind, or crosswind.
Dennis-

Pilot trim is much different than aircraft trim. Aircraft and helicopter trims are set by the maintenance pilot, so it is different. It is a bit like trimming the rod ends during the maiden flight wringout. Pilot trim in scale aircraft is mostly dependent upon load cg, performance settings, and weather.

I have some reference about trimming at full throttle, but I forgot where that is at the moment. I just don't know enough to say either way is best.

Having flown both analog and digital trim radios I prefer digital. Set it and forget it.

On my alpha 60 i had it all set on the ground per book instructions,Section 7 page 15 but when i takes off it climbs at a fast pace,i've readjusted the elevator but it needed more so i readjusted,but it still wants to climb,i think i have turned the adjustment a full six turns and it could be more but i've trimmed the tx,i'll wait til i get some calmer winds before trying it again,all this is at full throttle.It has a 17 oz tank and full if it makes any difference.

The typical trainer is VERY difficult to trim so it does not climb at full throttle.

The trainer USUALLY (I have a couple of examples where this is not true...) has significant "decalage" or angle of incidence difference between the wing and the horizontal stab. That angular dfference is similar to holding a lot of up-elevator all the time. When an airplane has this decalage, increasing airspeed increases the downforce on the tailplane, and lifts the nose. The nose lifting puts the airplane nto a climb... and the climb requires more power than level flight, so maximum airspeed is somewhat limited by this part of the airframe design.

You can overcome this by shimmng the trailing edge of the wing up, thust reducing the decalage. However... its not really recommended. (by me... Others recomend it all the time as a way to improve aerobatic capability.) If you make the change... then you are sacrificeing some inherant stability for the increased airspeed and some increased aerobatic performance. (particularly inverted flight) You would also be taking out a designed airspeed limitation effect...

See my post about "GREAT BOOK" (posted today) and if you can... find a copy and read it...

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Your oversize tank will have your model a bit more noseheavy than normal when its full... requiring more up elevator for the same level flight speed, and making higher speed pitch the nose up more.

BUT its inappropriate to adjust the CG for the larger tank...

Do test-trim flights with very little fuel (3 to 4 oz at take-off) in the tank to determine how far back it is safe to move the CG. (you can almost always move it back some on a trainer vs what the instructions reccomend. AFTER you have learned a bit about controlling the model.)

Be careful about excess climb-out angle with a low fuel level... you don't want a dead-stick on take-off.

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There are all kinds of "trims" involved in an aircraft. But ALWAYS... IN FLIGHT you trim the elevator to match the desired level flight airspeed. Whether by constant pressure on the stick, or with a bendable (not adjustable in flight) trim tab or with a trim-wheel.... The elevator "trim" controls level flight airspeed. The throttle controls if you have the power to maintain that speed in level flight, or if the plane is going to climb or dive due to excess or inadequate power.

The transmtter "trims" are actually equivilent to having an adjustable spring on the control stick in the full scale aircraft... to vary the tension applied to the stick, taking a load off of the pilot's arms.

Thanks for the info,it makes sence to me but the fuel tank is forward of the wing so to me it would make it nose heavy and want to dive rather than climb,the engine seems to have enough power but with all the wind i havn't had a chance to play with it that much yet.I was thinking about moving the aileron settings but i'll not do that.
Thanks again.

With no other changes... more weight in the nse makes the airplane dive.

So to take off... you put in more up elevator.

Fill the tank and take off.

Trim for level flight just a bit above stall speed, and add power, the nose will rise.

Leave the trims alone and land. Drain 13 oz from that 17 oz tank (should still have over 3 oz... just one pass around the field won't burn much. Or drain it competely and put 3 to 4 oz in.)

Take off again... you won't need to touch the elevator... the plane will rotate on its own at just a bit above the previous level cruise throttle setting.

Don't touch the trim!

The plane will constantly need down elevator to stay level even with a slightly lower power setting. It may even want to stall all the time rather than being able to have the power set easilly for level flight.

Try a MORE power and let it settle into a stable climb, then slowly reduce power until it no longer gains altitude. (still don't touch the trim...) THAT will work. (This is flying on the "backside of the power curve" See the book I referenced.)

Pulling up (if on the backside of the power curve) will make the plane MUSH and lose altitude.... it WILL NOT CLIMB with up-elevator! PUSH a little down elevator and watch it ZOOM up!

THAT is flying the wing... rather than pointing the prop.

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Demonstrate that at the local field... the trick of climbing with down elevator will AMAZE 80% or more of the pilots.

Hmmm...makes sense but I wouldn't want to fly my planes set up like that. Seems counter intuitive and might get a pickled finger flyer like me in trouble. Typically I trim my plane to fly straight and level with the throttle at half to three qtrs. open. At full throttle the plane will gently climb, and any thing below half throttle, the plane descends.
This is how I like for mine to be set up, but I am sure it depends on what and how you fly.

You balance the plane with the fuel tank empty.

When you fuel up your plane will be nose heavy, HOWEVER, when your fuel is low or you run out of fuel, your plane is properly balanced so you can land.

A nose heavy plane does reduce performance, but a tail heavy plane does not fly well (or usually very long) and is a HANDFUL to deal with.

One thing that's been forgotten is that to reduce trim change with power change, you adjust the thrustline of the egnine. If the airplane tends to nose up with power application, and nose down with power reduction, then you need to add some downthrust to the engine. Just shim a bit at a time. Small washers will do. While a properly-trimmed model should climb with power application, it should not strongly pitch up. The same would be for power reduction, the model should not strongly pitch down. In either case, the model should move ahead straight, and then smoothly move into a climb or glide when the power is changed.

I your model tends to go very nose-up and climb like crazy when you add power, do a thrustline change first. Don't mess with the incidence angles of the wing and stabilizer until you've eliminated everything else. A thrustline change can make a model settle down very well.

bax