I just finished building my pt-60 and took it to the field sunday. Plane took of great but would not bank with aileron input, had to use rudder instead. Everything else was just about perfect. Next, I tried moving the servo connections in on the aileron control rods and maxed out the servo rotation on my radio. This helped and the airplane can now maneuver with aileron input. However, the plane is very slow to roll. Granted it has a 71" wing and 2" of dihedral on each side, it is slow. I am looking to increase the roll rate as the slow roll rate makes the plane hard to recover without rudder input when inverted. I am looking into extending the aileron size by at least a half inch or so, any suggestions? My next step will be to move the servo connection on the servo to the furthest point forward to get max throw, however, i am certain that this will still not be enough to get an acceptable roll rate. Obvioulsy, it can roll quickly with rudder and aileron together, but i would like a lot more aileron roll. Another issue is that the servo seems to be a little sluggish, there seemed to be no binding when i installed the hinges. I am using a JR st-47 sport servo. I think putting in a faster servo would help a minutely to speed up the roll and give me faster reaction times.
The next issue would be my elevator, while it is pretty sufficient, i think the plane could use a bit more control surface. I have maxed the elevator out in its area between the stab and fuse. I was thinking either put a larger elevator on or cut the stab and fuse to get more of an angle, any ideas?

I think the airplane would be a better trainer if it could have a little more control for recovery. All in all i was impressed at how well this plane flew. It was fairly smooth and could land with very little air speed, I think this will be a great trainer when its finally tweaked out. Coming from a CG falcon 56, this is a very tame plane.

I''m a beginner too, and if I were in your shoes I would try a better servo; there are Hitec Servos for $13 that offer ball bearings and are rated at 20% faster (if you are using a 4.8volt battery, the speed for your servo is .24s, and the hitec is .19s). Extending the control surfaces past the edge of the wing will change the entire shape of the airfoil at any position, making your plane more unpredictable. You can even step up to faster servos with more torque, and any servo upgrade you can use in the future on you more advanced planes.

A faster servo will not make your plane roll faster.

What you need it more control throw. That means moving the pushrod out on the servo arm (or installed a longer arm) and/or moving the pushrod in on the control surface, or installed a shorter control arm.

You might need more torque on the servos, since as you increase throw, you decrease the mechanical advantage of the servo.

An easier mod to do before replacing the ailerons is to use dual aileron servos. Cut the torque rods off where they exit the aileron, since they sometimes limit available throw. Now mount servos half way out on the wing driving the ailerons directly.

However, there is a point where you''re just asking too much.

Oh, and making longer ailerons won''t really change the airfoil in any important way. It is a viable way to increase roll rate, but it also makes it easier to get aileron flutter. A single servo moving the aileron at it''s root means the entire length of the aileron is free to flex. A servo driving the aileron at the center means the aileron flexes less and you get more effective throw at the tips. And it''s at the tips that you get the most effect from the ailerons.

Also, try moving the CG back. that will really help your elevator AND it will help the roll rate, and make the rolls smoother as the nose will drop less when inverted.

The PT 60 really is not designed to do rolls with authority. It is a trainer that is really designed to self correct itself out of a turn. As mentioned getting a faster servo will not help any at all. You will need more throw to make it roll, however do not expect much at all, as the PT 60 is a trainer and with all the diheadral in the wing, it really does not like to be up side down. Good Luck, Dave

Im not new to the sport, ive been flying for about a year and a half on my falcon 56, I was looking for a reliable and easy to fly airplane, which is definatley what i have now, to tame for for desires. I would call it a sunday cruiser, but it is fun to fly after a long break over the winter. I may try putting two servos in the wing, that is a good idea. First i guess i will completely max out the servo arms and see what happens. I thought the sport wing design would be a bit more "able" upside down and with rolls but you get what you get, being a flatbottom wing i should have seen it coming. I have a wing to a bridi krafty 60 which i may buy next, it has a semi-symetrical wing, or i may just go for a kaos. Also the plane will roll pretty quickly with ruddder kicked in so I could just learn to use the rudder more often . It is not the best at self righting itself. It seems like it would be bad to get disoriented end up upside down and not have enough aileron authority to roll back over quickly. But like i said it flys great just cuising around at full throttle.

If the wing happens to be 2 piece, I would take out all the dihedral, it will fly much better.

You might also check your hinge gaps and seal them if necessary.

I considered taking out the dihedral, however it is a solid wing and that would require a lot of cutting.

You can increase the amount of throw in a control surface, aileron in this case, by moving the pushrod OUT on the servo control arm. You can also get more throw by moving the control rod IN towards the control surface.

Ken

I too would look at moving the cg back a little at a time. The fact that you say you run out of elevator leads me to that. Moving the cg will also assist in rolls.

Great pictorials, Ken!

if you want better roll rate with this airplane you need to build the wing with less dihedral,i did mine and only have about 1 inch in each side that made a lot of difference.i also built mine with duel aileron servos.dont expect this plane to act like a sports type airplane though, it is a traier.

Thanks for the advice! I''ll try *****g out my throw and moving the cg back before i consider taking out the dihedral.

Is it a big job to add dual aileron servos to a plane that is not originally set up for them? (By big job I mean more than removing say an 8"x8" square of covering, adding a balsa support, fishing a servo extension through the plane, recovering and installing the servo, etc.)

Kat, you are ready to do it, aren''t you? Just before you start, look at a couple of wings that were built for 2 servos, once you see it you will understand exactly. Good luck!

Well, I''m shopping for #2 with big plans for the future Think I''m going to go with a cheap low-wing trainer so I can start making mods without worry. Nitromodels Low-wing super aerobatic trainer is a $70 copy of the Goldberg Tiger 2, and people I''ve talked to say its pretty fast, and since I want a plane with flaps this sounds perfect; first upgrade to dual aileron servos, then cut ailerons and put servo back in original bay and add flaps. Play around with this and I''ll be ready for a more serious plane for #3 and won''t have spent a lot of $ in the meantime.

You can also seal the hinge gap lines. Beats me how much of a gap to have.
I''ve seen kedets with 1/4" gaps.lol

anyway, if you seal it you'll get more air flowing over the control surfaces.

I go with the moving in on the control surface side....only

If you move it out on the servo side, you''ll loose torque.... more throw,but no torque.

You can just mount two servos side by side at the center of the wing , if that's how your set up is.
Not that big of deal. No need to run extensions...cut into the wing and...etc
Just use a Y harness and you're done.

you can even couple the servos...when you see the set up...you'll laugh..it's pretty simple.

It doesn''t matter if you move out on the servo or in on the surface, the mechanical advantage is the same either way. What matters is the angle of rotation of the control surface vs. the angle of rotation of the servo (measured in degrees (or radians if you want)). If you change anything, and cause the servo to move the same number of degrees, but the surface to move twice as many degrees as it did, it''s going to require twice as much torque to do it, given a constant force against the surface.

(in fact, it will take more than twice the torque to move a surface twice as far, because the pressure against the surface also goes up as the deflection increases, and that varies with airspeed)

It''s actaully backwards...to where u get a longer handle or breaker bar to break a nut free...remember.
The closer you mount to the center of the servo the more torque.
it''s also stronger when it''s pulling..remember. More noticiable on the rudder.
On a single servo set up...the side that''s being pushed..is just along for the ride...sort of speak.

you will want it to be pulling when the control surface is on the up posistion.
So the best place to obtain this is actaully when the servos are mounted at the center of the wing
becuase the servos will be posistion on top of the wing instead of under. for a low wing.


another thing you can do is just clip the wings

I''m not sure what you are saying here.

That torque is used to push against the forces on the control surface. The larger the control surface and the faster you fly, the more force required to move the control surface away from center.

A servo has to work harder if you go farther out on the arm exactly for the reasons you describe. The servo has a fixed amount of torque. And moving the control arm farther out makes it harder for the servo to move the pushrod.

Along the same lines, moving the control linkage IN on the control surface is shortening the leverage the pushrod has against the control surface, meaning the servo again has to work harder.

I have a PT-60 and it exhibits the same slow aileron authority as you described. This plane does not want to roll without rudder input. Two other guys in our club have the PT-60 and the story for them is the same so I have to believe it is the design. After awhile, the plane does get a little boring but that''s how I like my trainers.

Good luck

Rufcut

On another subject, what would be a good plane to get into after a falcon 56. My falcon is a pretty aerobatic plane, being a sport trainwe. I have not mastered it yet but would like to start building something to step up to. I was thinking a bridi killer chaos. Any suggestions?

I suspect my Hobbistar 60 ARF is similar to your plane. After reading an online article I decided to not use the single servo in the center and installed a servo in each wing panel. Also elected to center the servo in the length of the aileron as this was supposed to minimize the likelihood of flutter.

To be honest, it wasn''t difficult at all...just time consuming while I waited on epoxy to dry. I covered the small gap on all control surfaces too.

I feel the same way about the roll rate on mine as you do yours and suspect its just part of a docile trainer''s characteristics. The most I would consider doing myself would be to extend the throw on the ailerons if any more is available and take it for what it is.

Already have a Stinger 60 kit in the attic for my next plane and if it weren''t for that I''d be looking at a 4-star 60. If you haven''t tried a good kit build you owe it to yourself to give it a whirl.

Regards,

Clay

I built this plane from a kit, had some rough spots but thought the end result was great and would enjoy another build. I would rather build my own plane and make some mods and understand what is going on in the plane. The pt needed very little trim and flew great minus the aileron control. I enjoyed the build and i am looking for another to begin, a low wing, more aerobatic plane. I have a dirty birdy 60, original bridi kit, that is about 40% built but it''s far beyond my capabilities to fly, it will be a while before i build it.

I have a couple of PT 40s, here is what I would do:

1) Increase the throw - if that does not work:
2) mount individual servos for the alierons, this will help increase the throws - if that does not work;
3) take the wing apart to take the dihedral angle out - this is some work, but will make the plane fly much better. If that does not work
4) buy a new wing kit and build it without the dihedral, you will be happy you did - more work and more money, but the best overall solution.

I hated the dihedral in my first PT-40 wing, I wanted to replace it, and went to get a wing kit, I found out a new full kit was $15 more, so I bought the full kit and rebuilt everything (much better the second time BTW). I met a guy at my club who burried his PT-40, killing the fuse, but the wing was fine, he gave it to me, so I converted the first one to a tail dragger and I have a spare wing that I will never use because of the dihedral.

BTW - they are trainers, so even now with a lot of throw, high rates, dual aileron servos and the low dihedral wing and it still has trouble with doing a roll.

Hey guys, The PT-60 is a large, very stable trainer. Even with the lesser dihedral sport wing, it is not a great acro plane. It just isn't made for it. I had the exact same surprising no-aileron control on it's first flight. Just goes to prove you still need the rudder to fly. All I did is increase the control throws, by moving the linkage out on the servo wheel. Remember to keep the aileron differential in there to keep the amount of rudder needed to fly coordinated down. (Adverse Yaw) You still need it! This thing is still my most used airplane. So versitile. Skiis, floats, and sometimes wheels. I wouldn't mind putting in dual aileron servos, but I would also do flaps so it would be much more involved. Too bad Great Planes doesn't make a wing kit for it anymore. Since you already have the wing built, I would just fly it as is. Keep it in mind for your next project though. Keep flying.