Hello All,

I am a beginning rc pilot, took my Avistar 40 to the field 55 miles away( [link]http://www.tulsagluedobbers.com[/link]
had someone more experienced than me help trim the plane out. After all adjustments the plane still continues to climb slightly. One pilot suggested that i put washers under the engine between it and the mounts so i did and it still wants to climb. It's the ARF version so did i do something, can i adjust it a better way? Thanks for your help and opinions.

By putting washers under the motor mount, I will presume that they meant for you to put them on the two upper firewall mount bolts. That would give your your engine a downward thrust. (Correct me if Im wrong folks). also only use one washer per bolt at a time. You may re- evaluate your CG as well. It may be a tad tail heavy.

When does it climb, at max power or at idle?
Changing the engine thrust may not be the answer.
There is not enough information to make any recommendation

I think he means that he put the washers between the engine and the mount. I don't know how, but that's what I understand from your message, cegfamily2.

Anyway, whatever you did, do what SoonerAce described. And, if that's what you did and had no luck, check the wing incidence. That is, if you don't know, the angle that the wing has in degrees to the thrustline. I think that if you had the CG too far back you whould have noticed more bad tendencies

Hope I helped

Geistware is correct, we need more info. It's typical of most trainers to climb slightly when the throttle is advanced. If your's is climbing constantly no matter what the throttle setting is, then it most likely just needs a little down elevator trim. If it climbs excessively when you advance the throttle, it may have a little too much positive wing incidence or possibly need a little down thrust on the engine.

It climbs at max power, then slightly when flying half power. The engine mount is like a clamp, not bolts through the engine. The only bolts are the ones that hold the clamps to the firewall.

If it's still climbing at half throttle you just need a little down elevator trim. Trim it to fly level hands off at half throttle and you should be fine. It may still want to climb slightly at full throttle which is fairly normal for a trainer.

Maybe cegfamily2 has "used up" all his radio trim. In which case he needs to make a mechanical adjustment on the elevator control horn.

by definition, any plane, real scale or model, climbs under throttle.. the more throttle, the more lift.. you need to trim it for a given power setting (ie: if you fly at 1/2 throttle, adjust elevator trim so you are level at 1/2 throttle).. All planes will climb with throttle, some just do so more than others,

Sachin

Yep, all trainers are going to clig at full throttle.. get up there and fly it (With out any more elev. trimming) And see what speeds you like or tend to fly at.. Then trim it at those speeds.

RCJon is right.

If you have setup your equipment in the plane to balance it on the CG as the instructions say, you dont need to mess with thrust. The firewall should have had the propoer thrust built in.
You just need to adjust the linkage to get the elevator linkage right, you probably started with a little up elevator at neutral trim. Turn the radio on and see where your elevator is at with the elevator trim as far down as it will go, just like it was after the last flight you mentioned. If it is straight with the stabilizer (neutral elevator) you probably started out with the linkage in the wrong place. Leave everything on and move the trim to center and then adjust the linkage by shortening the pushrod to put the elevator back where it was with all the trim in after you finished flying. That way when you take off the plane will fly just like it did the last time you flew, but you will have trim control again.

A trainer should fly hands off at mid throttle, but will climb a little at at full throttle.

Not so, depends on the type of aircraft. A straight, fully symmetrical wing plane such as an Extra, Cap, or Edge that is properly set up with zero wing and stab incidence won't climb when the throttle is advanced. The tendency to climb with added power is usually due to the wing having positive incidence. As air speed increases, the wing's angle of attack causes the plane to gain altitude.

I also say that it should not climb under power. Adjust the thrust line so that once trimmed out at medium speed, any increase in power simply increases speed. You need to put washers under the top two bolts between the firewall and motor mount to make the engine point more downward. Nothing is more disturbing to me than to have to readjust the trim every time you readjust the throttle, no reason to have a plane so out of trim that you have to constantly change elevator trim with throttle change.

If it is climbing more as you add throttle, I would then add a little down thrust.
Not much, just a little

Geistware, Rodney, & Stickjammer,

cegfamily2 is asking about his Avistar 40, for chrissakes. I think he needs a little bit of elevator adjustment. I'd suggest he work on that until the plane flys hands-off straight and level at 1/2 to 3/4 throttle before he gets all worked up about wing incidence and thrust angle. This _is_ the beginners forum.

My 2 cents.

Could be a CG issue however like prev stated a normal phenominon for a plane to climb under power and visa versa.. The best thing he could do is just trim it here and there throughout the flight if his skills will allow.. I have noticed nowadays that some guys cant trim there planes by themselves.. I see guys maidening there planes and some other guy moving the trim buttons for them.. Just my $.02

I had an Avistar as my trainer and it did the same thing. During my instruction, I was told that speed controls lift and elevator controls direction up or down. The faster you go the greater the climb rate. (At least on a trainer) All I did was trim the elevator to fly straight and level at 1/2 to 3/4 throttle, which is where I flew it during most of my training anyway. Like rcjon said, trim it and fly it before trying all the other stuff. IMHO

It is not at all unusual to change engine thrust (both down and right) many times during the first few months of operation. Some changes will be to suit your own flying style that will be evolving. Some changes will be to accommodate the invariable minor differences that creep in during assembly. And yes every bump up repair will introduce more changes to CG and control throws and alignments.

Hopefully the airplane will zero in exactly to your liking before the expiration date.

Wow! I can't believe you drive all the way from Bristow to Broken Arrow to fly. Isn't there anything on the west side of Tulsa that's a little closer? I haven't lived in the area for over 10 years, so I wouldn't really know.

BTW, I'm in the camp with the people who say don't worry about a little climb with full power right now. Trim for level flight at 1/2 throttle. Ask your instructor if he thinks you need to adjust the down thrust. Washers behind the top holes of the engine mount is a good way to do it, or use wood shims.

Have fun!
Scott

I had the same trouble with my Hanger 9 Extra Easy. I got all kinds of suggestions including putting popsicle sticks under the trailing edge of the wing at the fuselage to decrease the angle of incidence of the wing. All it took was an adjustment at the elevator control horn to have my transmitter trim fully functional again.

More speed = more lift -- always. Trim it so that it flies as you want, at the power setting normally used for most of your flying, & do it by adjusting the elevator clevis so that your Tx trim is at neutral. Don't mess with the incidence, or thrust line (at least not in the vertical plane), they will be factory pre-set, & the Avistar is very seldom out of whack in that regard. It is often usefull to trim for level flight at ~ 3/4 power, where a lot of flying takes place. This will give your Avistar a modest climb at full power & a modest decent at approach power. If you always fly at full throttle, trim for level flight at full throttle, but be prepared for a sharper decent at lower power settings.

rcjon,
Maybe you should go back and read post #7 before you include me.

My bad. You did give good advice. Sorry.[&o]

LOL, Aint America great!!

Ain't no thang!