My one and only plane is a Four Star 40 ARF (powered by OS46FX, APC 10x6). I love it! But I have some problems with it:
1.The wing rocks. I was like this from the beginning. I noticed that the aileron gaps where not the same so I sealed them completely. Also, the aileron servo had gaps (inside the gears) and the ailerons where not stable. Servo replaced. Wing rocking solved let’s say 70%. Is the rest 30% caused by the wind? It happens at all speeds.
2.I am wondering about aileron position and incidence. I used the aileron position guide (ASP) that SIG provides but they look like permanent flaps to me.
3.When slowing down too much the plane for landing, sometimes strong tip-stall occurs. A hard landing is the result. Tough plane this 4*. No damage at all. Only broken props.
4.Plane glides forever (like all 4*s). Long walk after landing if engine quits.
5.Bouncy landings.
6.When at half-throttled straight and level flight I give full throttle, the plane goes up. Do I need some down thrust? Plane had already some right thrust from the factory, so I thought there is also some down thrust already.
7.While taxiing for take off, plane sometimes ground loops. When I correct carefully and continuously with the rudder it’s usually OK.
8.I didn’t glue the wing very carefully and there was a gap between the two halves (0,63”=1,6mm). Filled gap with hot epoxy. The dihedral is a bit larger than it should be.
Any advice would be highly appreciated.
Harry

Hi Harry

A lot of your rocking may be caused by to much dihedral. If you reduce the wing span of that airplane by removing one bay from each wing tip you will have a whole new and much better flying 4 Star.
Your bouncy landings and ground looping are probably caused by the landing gear being to far forward. If you are flying off of a hard surface try placing the gear so that the wheels touch the surface 15 to 20 degrees in front of the cg with the plane level. If you are flying off of grass the angle will need to be about 25 deg. Also make sure that the wheels are pointed straight ahead or toe'd in a little. If they are toe'd out and cambered out (normal after a few hard landings) this will cause ground loops.
Yes you need a little down thrust. Add it in about a degree at a time. Better yet if you have a computer radio slave some down elevator to your throttle.
Retrim your ailerons. You don't want permanent flaps. If any thing you want them reflexed a little. Fix this before putting down thrust in the engine. Fixing the ailerons alone may correct your pitch trim with speed problem.

Denis

Denis

Harry

Did you position the asp on top of the wing the way the manual says? It sounds like yours is backwards. A 4 star normally looks like the ailerons are reflexed ... slightly up, not down like flaps that have been dropped. Tip stalling is a very unusual thing for a 4star. They float forever.... usually too long for some not used to it.

What the man said: the ailerons have to look like they're UP, not down like flaps. No wonder it's tip stalling.....

And oh, a 10X6 is really too small for that plane/engine combo. You'd probably be a lot happier w/ a 11X6

Thanks a lot guys. I am sure that I positioned the tool like the manual says. Or maybe not... I took some pictures but it was impossible to upload them. I don't know why.
Harry