Having problems with a Right Flier 60..top wing trainer....the plane porpoises around neutral, it seems to be a little sensitive on the elevator. It seems to be tail heavy, but I have check the CG and it checks right on. Someone suggested that the incidence was off ?????
What do you all think..[]

Your elevator travel might be excessive.
The elevator pushrod might be rubbing/jamming on something.

I have instructed new R/C flyers on several examples of this airplane, and they all flew well, although the wing center section needs reinforcing to avoid failure in flight. Sounds like excessive friction in the elevator pushrod to me, as Tall Paul suggests. The manufacturer's suggested elevator travel should work fine unless your CG is well behind the recommended position.

Yes, sounds like a problem one way or another with elevator. Make sure the linkages are tight with no free play, but also without excessive friction or binding.

I have checked the elevator push rod...no binding, deflection of elevator slightly less than recommended. I did re-balance it and made it a little nose heavy...will see when I fly it
again on Monday.
Note: Their is another Right Flyer .60 with the same problem at the field ??????

Thank you all for your suggestions.

codimasta,
I'm curious, what do you mean by "porpoise"?

Do you mean at different throttle settings it either wants to climb or descend?
Maybe your thrust angle is pointing up or down.

Do you mean with the same throttle setting it either wants to climb or descend depending on the speed?
Maybe you are nose or tail heavy and you are trying to compensate with elevator trim. That's okay for a given speed but if you raise or lower your speed, the trim setting will have more or less of an effect respectively.
Or Maybe you're trying to compensate for an incorrect incidence angle at the wing or stab by using elevator trim.

Good luck!!

I have seen 2 Right Flyers in action, with no special "porpoising" action. However, I have experienced it twice, myself.
Once, with a Lazy Bee, I had WAAAAY too much elevator throw. It made the elevator too touchy around center. I reduced the elevator travel, and the problem went away.
Once, with a Four Star 40, the servo tray became loose in the fuselage, and would slide fore & aft before moving the elevator. Made for an uncomfortable sort of pitch control. When I made the tray solidly mounted, there was no more problem with that.

Good luck,
Dave Olson

A "porpoise" type instability is called Phugoid motion. It is when, given a small deviation from straight and level (either from pilot control or a bump in the wind), the plane will alternatively pitch up and down, slightly speeding down and up, respectively, continuing the pattern for many sine-wave looking iterations.

This dynamic instability can be due to insufficient stabilizer aera or an insufficient tail moment arm, and it can be exacerbated by having a very small static margin (CG close to AC).

Having said all that, this might not be your problem. I have seen this on high wing trainers more than once where the root cause was positively identified to be insufficient and/or weak rubber bands on the wing- the wing was actually lifting a bit in the saddle either when going fast or increasing AOA. If you use rubber bands on the wing, try using more/new rubber bands.

Since I did not assemble the model, only the instructor, I decided to take the model home and check it out. This is what I found...checking the elevator pushrod for binding, I did find some bind (this is one that used a plastic outer tube with a metal pushrod inside), at first I thought it needed some lubrication, it did not do anything, I pulled out the metal pushrod wire out and low and behold there was a S- Type bend. I replaced it with a nylon type pushrod and it is smooth
as silk. The next thing I did was to check the CG, using the cup holder method, remove 1 oz.
from the rear-end, and added 1/2 oz to the left wing panel. Test flew it today and it was a different plane.

Thank you all for your advise, I made a copy and gave it to the student, hopes he will learn from
it...

Thanks again to all.Larry AMA 11269