Throttle trim
 

Might help beginners. More quiries while I work on my midstar.

How do you trim for throttle? Level flight at 1/2? level flight at wide open?

I used to do the latter, but now do the former so I can use throttle to adjust for altitude. What say you?

peace

RE: Throttle trim
 

With a flat bottommed wing Itrim with elevator to fly level at about 3/4 throttle. With symmetrical wings the same, but it doesn't matteras the models don't climb much with added throttle.

RE: Throttle trim
 

this is one of those questions that you'll get alot of different answers, the one i went with was trim at half, that when landing and you need to suddenly abort, when you go to full throttle the plane will want to climb

RE: Throttle trim
 

This topic will be alot of debate. I prefer to set up airplanes that will require little to no trim change at any power setting. The trick here is to get the wing, stab and thrust angles correct and then work on CG. With a flat bottomed airfoil, I set the wing to -1 degree, with semi-symmetrical I set them to 0 degree and symmetrical I set to +1 degree. The stab and engine are set to 0. Don't assume that an ARF has everything set correctly. Many times they do not. Now if you find your model trims at full throttle but dives at 1/2 throttle, you need to move CG back 1/4" at a time untill it stops. Keep this within reason and never move the CG back more then 35% of MAC. I'm sure I will be debated on this as I was on a different thread of the same topic. The issue was that a model was landing faster then the poster wanted and I had suggested moving the CG back a tad.

RE: Throttle trim
 

I set trim at 1/2 throttle or just a tad bit more...this is where you do most of your flying....I want to climb with power on...I can't think of a time I want to decsend with power on

RE: Throttle trim
 

G'day

I trim my models to fly level at about half throttle. Then if I want to climb, I increase the power and if I want to come down, I reduce the power.

This also has the advantage than when you are landing, reducing the power does not make the plane suddenly nose dive and makes landing easier.

It also saved a friend's Kadet Senior recently when, with the throttle at about half, he took off and then found he had no control thanks to a battery problem. The Kadet climbed gently then went into a gentle left turn (like a big free flight model). As the uncontrolled flight continued the circles tightened slightly and she started to gently loose height eventually landing in an adjacent field on its wheels with only one puncture in the covering. The prop struck the ploughed ground and the engine stopped with the planes sitting neatly on its wheels. He is one lucky lad.

Cheers

Mike in Oz

RE: Throttle trim
 

Though it depends upon the characteristics of the model ( including wing type as previously mentioned ) I tend to like my non-trainer planes neutral at all throttle settings.

That said, I typically trim mine out for level flight at 70-80% throttle.

That way I can take my hands off the sticks without worrying about the plane, in case I need to do something quickly while flying...

e.g. adjust glasses, fix a hat, etc.

RE: Throttle trim
 

This largely depends on your individual flying style. I typically trim models for level flight at a throttle setting of about half. Pilots that own "underpowered" models or enjoy the thrill of speed may trim at 3/4 throttle. Likewise, pilots attempting to maintain a scale appearance may trim as low as 1/4 throttle. What most modelers don't understand is that your elevator trim is essentially setting your airspeed, not altitude. A stable climb or descent can easily be achieved with a higher or lower throttle setting respectively. This technique will allow the aircraft to maintain a constant airspeed, so find a comfortable spot and trim to maintain it.

RE: Throttle trim
 

For me, it depends on the model. For aerobatic models like my Extra, power changing pitch trim messes with flying the sequences, so it's something to trim out.

But for flying a scale cub or even a trainer, I use the elevator trim like the full scale guys do. I change it to match the airspeed I want to fly at at the moment. If I'm roaring around with the trainer, doing the "trainers can't do that" thing, then I add in a bunch of down elevator trim. When I'm flying down the field backwards in a breeze or just floating around, I add in the up trim. If I'm shooting touch and goes and messing around with slips and one-wheel landings, then I'll trim somewhere in the middle to make the landing approach look like what I want it to look like at the moment.

Remember, elevator trim controls your airspeed, throttle controls altitude. Elevator trim isn't a "set it and forget it" thing for that type of model. So don't be afraid to adjust the elevator trim during the flight depending on the model and how you're flying it at the moment.

RE: Throttle trim
 

I trim all my planes these days for hands off flying at about 1/2 throttle. The trainer because half throttle or just above is where the plane is flown. My pattern and IMAC planes have a neutral CG and they will fly until they run out of fuel straight and level at half throttle with hands off. I don't really use the radio trims much, a beep here and there as the weather requires. My control surfaces are set at zero degrees up and down. CG is your friend. A flat bottom wing is designed to lift with speed so it's another animal.