Precision Aerobatics Extra 260 problems??

[Gonzoman]

This is for any one that has a problem with their PA Extra 260. This is a very good plane, but there are issues with some of them, and now's a good time to solve them.

One problem is wing rock. Besides the obvious, 1st check for warps I had one in each ail. The rep from PA told me less expo helps too (more responsive) depending on your stick length and your personal preference. Also just being a small plane with little 3D experience. Any other suggestions would help very much .

There is another problem with my 260 it flies tail heavy no matter what the cg 90mm 100mm doesn't matter. I'm not saying it is tail heavy, but just flies that way in regular flight. I am trying to get this resolved with PA. I might need a new fuselage I don't know yet. I have about 2mm down trim for level flight at 1/2 throttle. full throttle it climes like a banshee from level flight w/o any input. Landing requires even more down trim just to get the plane to settle in. If i don't give it down trim I have to fly it down risking the plane on landing. If there is any wind at all forget about flyng, I mean landing, it's a handful to say the least, but has to be done (I live in the desert that's always windy). I'm pretty good at landing anything else, but this one. I think it's my plane in particular, and maybe others also. The plane has bad coupling to the bottom in KE. It could be the down trim. All tests indicate a tail heavy plane even though I went to the extreme and balanced it at 90mm on my machine, still flies tail heavy even though it's not. I don't have a lot of experience tuning an airframe, but this is defiantly learning me somthin' good. I'm hoping PA will help me resolve this problem they've been very helpful so far.

[scott m lyons]

Check you're wing and stab incedence.

[JAS]

Check up and down thrust, just like you would left or right thrust.

[3D Master]

I have this same plane, same scheme. The plane flies very well, wing rock like a mutha though, but look at the short coupling on the tail surfaces, ex, the fuselage is so short which will make this airplane TUMBLE like no other! And Snapy! I love this plane! I have not encountered the landing problem that you are speaking of. Mine settles in real nice and lands smoothly! So i can not say that on other PA 260's are the same, i have flown numerous PA 260's from people that have them in the area, flown over 10 probably, it will couple badly in Knife edge because of the short coupling in tail moment. Just program it out in the radio if you can. I can not think of anything else that could resolve that issue for knife edge flight though.
Thanks

[3D1]

I just got this plane and cant say enough about it.love this plane. I dont have any wing rock really and knife edge is great. cg is at 98mm. it hovers like a foamy. I did find that running a seperate bec like the castle helps speed up the servos running them at 6v. my elevator was twisted a little and once I straightened that its really flying straight. best 3D plane so far in this size. the tail was way off when building too and took a while to get straight. it sounds like your incidence is off with the wing rock and coupling issues.

[Jag01]

Funny I just stumble across this thread as I have been fighting a battle with this very same plane for sometime with the same issues.

Mine would wing rock in upright harrier and yet be rock solid in inverted harrier. Mine too was carrying a good 2.5mm (on the elevator) of down trim to maintain level flight and a vertical power off down line. I would pull to the wheel in knife edge (again little wonder with that much down elevator mixed in). The plane could be trimmed and cg adjusted to fly straight however it always felt to me that the airframe was fighting against all of the mixes and trim issues and that it was draggy as a result.

I checked incidences and this revealed a lot to me. The tail plane was not warped yet when checking incidence in relation to the main wing, one wing was +1 3/4 the other was +3/4. Ideally incidences should have been checked in relation to the canopy rails, however given the tail plane is glued in it becomes too difficult to adjust the incidence of the tail plane.

I elected to adjust the main wing I made some modification to the fuse to allow me to reposition the wing to change the incidences.

I would love to be able to say that my adjustments solved my problems, however unfortunately I never really managed to find out for real as on the test flight after adjustment the plane went "off air" and ended up a total write off.

I will say this though that immediately upon take off I pointed the nose vertical and with zero elevator trim if climbed dead straight for the first time in its life!, I then pointed the nose down in a vertical power off dive and it tracked straight down with zero elevator input or trim, again it had never been able to do this previously. Unfortunately this was the moment it decided to go "off air" and I could not pull out of the dive. So that abruptly ended my flight testing.

I do not believe the short coupling of this plane should cause the wing rock, I do believe there is an incidence issue with this aircraft that needs to be addressed. I have spoken at length with the designer who insist that their quality control during manufacture would illiminate this possibility.


cheers,

Jeff

[Gonzoman]

I've been working with Shaun the designer of this plane, and as far as wing rock first check the incidence between the two wings then the horizontal stab. Then check for warps in the wings, ailerons etc. Shaun also stated to me you have to have a very high AOA to stop the wing rock, it was the way he designed the air-foil.

I too had unwanted incedence in the stab Really the only way to remove it was replacing the stab. If you were to change the wing incidence to match the stab you would then have unwanted thrust angles. One other thing is to check the there is absolutly ZERO warps anywhere, and that the motor box and motor are flat to their respective surfaces.

One other improvment I found was adding a tiny bit of right thrust. Besides all that WOO HOOOO this plane is a blast to fly It will tumble and KE like crazy, yes with some coupling though. This plane is also extremely stable in any attitude, and has a build quality second to none.

If any one has any questions about their PA 260 contact PA, and I will gaurantee you will be taken care of, if it's something Steve can't help you with Shaun will definately be able to.