FT Tutor uncontrollable roll

[X_that_one_guy]

Hello, I just finished my first scratch build of an FT Tutor. I've got a 1120 kv motor with a 9 X 4.5 prop and a 1550 mah 4s lipo on it, trying to follow the recommed specs. My problem is that when I try to fly it, the plane rolls to the left while I hold full right ailerons. When I originally encountered this issue on my maiden flight, I shifted the wing to the left to move the center of lift to the left. This worked fine, even got it trimmed out,

until I crashed it after flying it in the direction of the sun, lost sight and control. After some minor fixes, including rebuilding the power pod, it still rolls if not worse. The only solution I found was to strap a weight to the right wing, but I'd like to solve the problem in the first

place. I've balanced the wings and fuselage separately on my fingers, and nothing seems to be out of place. Could my angle of thrust be an issue? I built it to the plans? I'm also flying with the recommended CG placement with the battery in place. Any recommendations or fixes would be very much appreciated!

 

[AIRFORGE]

There doesn't appear to be any thrust angle down or to the right. Try adding about 1-2 degrees down, and 2 degrees to the right. Looks like you might have a bit of left thrust angle. You can put thin washers between the mount and the firewall. Start with 1 washer at the top and 2 on the left. Then make adjustments (more or less angle) from there.

 

[X_that_one_guy]

There doesn't appear to be any thrust angle down or to the right. Try adding about 1-2 degrees down, and 2 degrees to the right. Looks like you might have a bit of left thrust angle. You can put thin washers between the mount and the firewall. Start with 1 washer at the top and 2 on the left. Then make adjustments (more or less angle) from there.

That's the consensus that people have been giving me. If the plane needs some thrust angle, why dont the plans state it? Is it different from plane to plane? Thank you

 

[AIRFORGE]

I think the angle is built in. I'm gonna look at the plans...
(Edit: It's not built into the pod.)

 

[Houndpup Rc]

That's the consensus that people have been giving me. If the plane needs some thrust angle, why dont the plans state it? Is it different from plane to plane? Thank you

When you cut it did you cut it right on the lines?

 

[AIRFORGE]

It is not built into the power pod. Not terribly unusual, but it's normal to add in thrust angle to some planes.

 

[Houndpup Rc]

It is not built into the power pod. Not terribly unusual, but it's normal to add in thrust angle to some planes.

I didn't think it would be....Its not usually on bigger planes.

 

[AIRFORGE]

I didn't think it would be....Its not usually on bigger planes.

It uses a swappable power pod. No angle.

 

[Houndpup Rc]

It uses a swappable power pod. No angle.

Maybe uneven airfoil?

 

[AIRFORGE]

Maybe uneven airfoil?

I don't think so. It should have thrust angle adjusted into it to counter torque.

 

[Houndpup Rc]

I don't think so. It should have thrust angle adjusted into it to counter torque.

My FT Scout doesn't have it and it flies great!

 

[AIRFORGE]

My FT Scout doesn't have it and it flies great!

Hmm. Every single motor tractor plane I have has thrust angle to some degree.

 

[Houndpup Rc]

Hmm. Every single motor tractor plane I have has thrust angle to some degree.

That's funny. I have built a lot of FT planes (As you can see by my sig) and I have never put thrust angle on any of them except my mini mustang and the NN spitefire.....

 

[AIRFORGE]

Based on this image alone, I would say it needs to have more angle to the right.

 

[Houndpup Rc]

Would it cause that if the vertical stabilizer and the horizontal stabilizer aren't square with the wing?

 

[Foamforce]

This isn’t a thrust angle issue. That wouldn’t be nearly as dramatic as you mention. Also, I built mine to spec and it doesn’t have that issue.

Are you sure you don’t have the ailerons reversed? To go left, the left one should go up.

Are all your control surfaces, including the rudder, lined up nicely after you’re powered up?

Is your wing warped? If the left trailing edge is higher than the right trailing edge by even a quarter inch, it could do what you’re describing. If that’s the case, you need lots of trim.

 

[Houndpup Rc]

This isn’t a thrust angle issue. That wouldn’t be nearly as dramatic as you mention. Also, I built mine to spec and it doesn’t have that issue.

Are you sure you don’t have the ailerons reversed? To go left, the left one should go up.

Are all your control surfaces, including the rudder, lined up nicely after you’re powered up?

Is your wing warped? If the left trailing edge is higher than the right trailing edge by even a quarter inch, it could do what you’re describing. If that’s the case, you need lots of trim.

That sounds right!

 

[X_that_one_guy]

This isn’t a thrust angle issue. That wouldn’t be nearly as dramatic as you mention. Also, I built mine to spec and it doesn’t have that issue.

Are you sure you don’t have the ailerons reversed? To go left, the left one should go up.

Are all your control surfaces, including the rudder, lined up nicely after you’re powered up?

Is your wing warped? If the left trailing edge is higher than the right trailing edge by even a quarter inch, it could do what you’re describing. If that’s the case, you need lots of trim.

It's not my ailerons, I can fly the plane normally when I have one wing weighted. I lined up all my control services with a straight edge with everything powered up, then installed my servo horn and linkage stoppers. I was considering rebuilding the wing, I'll update when I do

 

[Foamforce]

It's not my ailerons, I can fly the plane normally when I have one wing weighted. I lined up all my control services with a straight edge with everything powered up, then installed my servo horn and linkage stoppers. I was considering rebuilding the wing, I'll update when I do

Weighting up one wing is just an odd way to trim it. You must just have a warp and need more trim and more aileron throw.

How much throw do you have on your ailerons? You ought to have about 30 degrees of throw on both sides. That would probably be something like 3/4” both up and down. If you don’t have that, move the control rods outward on the servo side. If that’s already maxed out, then move inward on the aileron side.

If you already had enough throw, then add a bunch of mechanical trim. Put your trim on your transmitter back to center. Then adjust your control rods so that your left aileron is about 1/8” down and your right aileron is about 1/8” up. This is a pretty big trim to make it roll to the right, hopefully enough to cancel out your wing warp trim issues.

If that gets it close enough to fly, then get it to, figure out which way you need to trim, bring it down, do a bunch of trim on the ground. Repeat until it’s stable enough to finish trimming it in flight.

Try this before rebuilding your wing! Your plane looks perfectly fine as-is, it just needs to be trimmed.

Good luck, post videos!

 

[Houndpup Rc]

Weighting up one wing is just an odd way to trim it. You must just have a warp and need more trim and more aileron throw.

How much throw do you have on your ailerons? You ought to have about 30 degrees of throw on both sides. That would probably be something like 3/4” both up and down. If you don’t have that, move the control rods outward on the servo side. If that’s already maxed out, then move inward on the aileron side.

If you already had enough throw, then add a bunch of mechanical trim. Put your trim on your transmitter back to center. Then adjust your control rods so that your left aileron is about 1/8” down and your right aileron is about 1/8” up. This is a pretty big trim to make it roll to the right, hopefully enough to cancel out your wing warp trim issues.

If that gets it close enough to fly, then get it to, figure out which way you need to trim, bring it down, do a bunch of trim on the ground. Repeat until it’s stable enough to finish trimming it in flight.

Try this before rebuilding your wing! Your plane looks perfectly fine as-is, it just needs to be trimmed.

Good luck, post videos!

Maybe his horizontal stabilizer was installed warped? I don't it would cause that much of a problem though....