Farmer Ted

My Feedback: (5)

I just built a Goldberg Laser 200 ARF (electric power) and it is a pretty plane that flies well but I am having a couple of handling problems:

First: during tight high G loops or partial loops (like a split-S) the plane will snap out and roll or spin to the right. The roll is induced by the amount of elevator applied and will actually fly through a large loop or larger radius split-s fine. I experimented a bit with reducing power during these loops and that seemed to help.

this roll to the right is also reproducible if sudden up elevator is applied in level flight...the plane will just about snap roll to the right.

During takeoff...the plane actually wants to pull to the right instead of the other way around (pulling left due to the p factor) decreasing takeoff throttle and lengthening the takeoff run helps this.

The stab is aligned perfectly to the wing, the servos are above the recommended torque, pushrods have been upgraded, the fin and rudder are within a degree or two of being perpendicular to the stab, everything seems to be aligned correctly.

The elevator halves are a little out of alignment with each other but nothing worse than any of my other planes and the way they are misaligned would theoretically cause a roll to the left under up elevator.

Based on some research I've done, I believe I have too much right thrust on the plane. (the thrust angles are not built in to the motor box...the motor must be shimmed with washers. Goldberg recommends " mounting the engine on the thrust line and stacking 4 washers to give approx 3-4 degrees right thrust. down thrust is not mentioned.

After all of that: HERE IS MY QUESTION!: every plane I've ever built had the thrust angles built into the motor box. I am unsure of the symptoms of incorrect thrust angles. Does what I described above sound like they are due to excessive right thrust. If so it is an easy fix to re-shim the motor.

Any help anyone could give would be great.

Thanks.


also...a landing question regarding the Laser 200

During taxi and takeoff runs I've really got to hold the tail down with the elevator or the plane wants to nose over. Landings are nose-over spectacles. I moved the CG a little bit back from the recommended place and it seemed to help this. Lowering the landing gear (to lower the center of the gravity on the ground) also seemed to help...this plane has really tall landing gear for some reason.


I have flown many other planes and can typically touch them down like a feather. To land the Laser I've either got to fly it into the ground and risk a high speed nose over OR I have tried flying with about 3/8" of flaperon on landing (just enough to flatten out the bottom of the wing) and the plane slows down and floats but then gets extremely mushy and wants to stall and fall out of the sky a couple feet off the ground.

Is this typical with the Laser design? if there are any Laser pilots out there...any landing suggestions would be appreciated.

The fact that I'm landing on gravel probably doesn't help but I have not had problems with any of my other planes including my Extra 300s or Ultimate Bipe. Even planes that like to land hot like my Super Sportster have been fine.

Thanks

R/CBOONE72

well, I just assembled a pretty much scratch built foamie, When I started out the first flight today, it was very unpredictable, rolling out in loops and everything. It was tail heavy, I moved the electronics foward and got it a little nose heavy and that helped. Then it still roll out in tight loop, the wing was twisted, and I can't fic it in the foam, it won't stay. You said your is rolling out, try checking wing for twist. If it is not then make sure the rudder and vertical are straight, roll out in loop could be a rudder trim issue. You said the stabilizer was all level. Was that to the wing? is it twisted through the fuse, no twist at all, you can look from front of wing and see that stab is perfectly parallel with wing. Then make sure wing is square on fuse and that the stab si to, if it is then give it thrust to the left or the oppiste direction of pull when taking off.usally the slower you go in a loop the more it wants to throw or drop a wing out and then spins out. Make sure it is balenced latterly to, not just CG being right, But like I said, check everything for square that I mentioned, if anything is off, fix it, go fly see what happens. If problem persists, toy with CG a bit, see what happens, move it both directions, in small amounts, try forward first then if it gets worst, try backwards. Then if nothjing happens, toy with thrust. But the diving problem still exists, maybe you have an incidence problem in the wing or stab. Is it heavily wing loaded maybe, maybe its to heavy somehow. But that seems like a CG problem. All I can say beyond what ive said is to toy with things, Everything I have mentiond fixed everything of mine that had problems. So Good luck