Two questions.

1. How do you correctly set the trim for throttle?

2. If you let go of the right stick it returns to center. Should trims be adjusted here for straight and level flight?

Thank you.

Trim for the throttle is actually the low-end trim, i.e. idle trim. You adjust it so you can idle as low RPM as possible while being sure your engine won't stall. The throttle trim does not affect the throttle above 1/4 throttle.

You trim a plane (with the other 3 channels) so that it flies straight and level, 'hands off'. If the plane rolls to the left, and you need right stick to hold it level, a few clicks of right aileron trim, and see how it flies, adjusting accordingly. If it's a HUGE amount, when you land the plane you can make mechanical adjustments and try again. Obviously you do the rudder and elevator too, so the plane doesn't turn or climb or fall on it's own; it flies straight, level, at constant altitude with no stick input.

Some radios have no throttle cut off (Spektrum DX7 for instance) so you don't have a switch to cut the throttle when you are done flying. So, the trim becomes both a "throttle trim adjustment" plus an engine cut "switch". So, when setting the radio up for proper operation, the trim should be about mid range. This gives you enough room to go high-idle or lower idle, and room to move the trim down enough to cut the engine competely.

Even if you have a radio with a throttle cut switch, though, you would probably want the trim set at mid range with the engine operating at it's (your chosen) idle RPM. Then using the engine kill switch should close the carb to the point where it shuts down.

And, as GaRCfield said, it's a straight-and-level hands-off operation you seek on your first flight of the day. Please.. if you are not familiar with this concept, get some help. I would hate to see you do this, go hands off, and roll the plane into a dive into terra firma. Not a good thing.

Once you take off, a simple soft climb rate and a mild turn to get in the pattern will work. Then center sticks, and remove your fingers from the sticks. NOT YOUR HANDS FROM THE TRANSMITTER (neck strap attached of course or else you would drop it.. [:@] ). Put your fingers right back on the sticks and fly the plane. Determine how what direction you need trim.. right aileron for instance, then one click at a time, adjust it to the point where it does not roll. If it climbs, one click of down elevator at a time.

Once you are ready, FINGERS ONLY off of the sticks and see if it flys straight and level.

Remember, though, adding throttle means you've just untrimmed your plane and it will not fly straight and level at the new RPM (speed) and another trim adjustment may be necessary.

CGr.

If your plane requires a lot of trim to remain straight & level then it needs to be adjusted mechanically (adjust clevis) once back on the ground. Ideally the trims should be approximately centered with the plane flying straight & level. This way you will know the trims are set right (approximately) during your pre-flight check. If one plane needs full right aileron trim and the next plane needs full left trim and the third plane is happy with the ail trim centered but needs full down trim, how are you going to remember all of these? This applies mostly to radios with mechanical trims as they can be easily bumped out of position. Radios with electronic trim and "model memories" will typically "remember" trim settings when you go from one model to the next.

I am SOO glad to see this posted by someone with experience, I just always have assumed it was normal to have to retrim my elevator when I change throttle speeds for any length of time. (Actually I trim it for an average speed for how i feel like flying and then leave it alone unless I want to slow down or speed up)
Thanks CGR!!

I think when you mount the fuel tank near the nose. It gets tail heavy as you go.

For that reason, you do the CG adjustments with the tank EMPTY for planes with the engine and tank in the front.

And, Audi, you're welcome. That was drilled into me by my instructor for practically every novice flight I did with him on the buddy box. So, I remember.. oh boy do I remember... But, it is in fact true. Moreso for trainers, but nevertheless, an ever present issue to deal with when changing trim.

CGr.

What Bruce said is so true. Case in point: The Nexstar with the "stuff" installed (wing tip spoilers and brakes). Removing the brakes made a very different feel of the aircraft and it required an awful lot of trim to fly straight and level. In fact, after flying it without the brakes, and trimming it for straight and level, I landed it and spent the next several minutes adjusting the clevis to put the stick back to center with the elevator trim dialed in mechanically.

CGr.

Thanks, Guys,

I plan on getting the Futaba 7C 2.4 GHz radio. I see the trims are digital and require a bump at a time in either direction. Does that radio give you an audible beep for each bump of the trim? Just wondering.

cap,

yes it gives a beep for each bump, it also has feature for the other channels where you can up the amount of movement with each bump of the trim levers for aileron/elevator/rudder. a nice feature for the first maiden flights .





bassman

And your "new" trims will be remembered for each plane you program.

Good choice on the radio. I no longer like my 6EX.

Some radios have the ability to mix your surfaces to throttle, so when you advance throttle the surfaces re-trim. Don't know if the 7C has that or not. If it does I may be buying one.