First Plane Rudder Pulls

[NYBackyarder]

I picked a Graupner Sunwheel Biplane as my first plane, and I may have screwed up the tail fin.

The plane pulls to the left in the air, and full right rudder barely turns the plane. It turns on a dime to the left... Full right trim doesn't help either. I can't adjust the control linkages to force the rudder to go right more because the plane has a steerable tailwheel attached to the rudder, and currently the plane taxis straight on the ground...

Aside from cracking the fin off and trying to recenter, is there anything anyone can suggest? I can attach a photo if that will help.

[Wings]

Does it pull to the left only when the motor is on, or is it all the time?

Is the rudder centered at neutral (no stick input), or is it angled to the left (possible) or right (unlikely)?

Is the servo arm perpendicular to the case at neutral? Sort of like (dots mean nothing; I hope this looks okay):

[Servo] [Rod]
======
|.........|....|
|.........|....|
|...O=====|= <-- [Arm]
|.........|....|
======

If the servo arm is way off center, you might have a situation where the travel limits and/or angle of the arm may severely limit the movement in one direction.

Is the tail itself aligned properly? Make sure the tail isn't leaning off to the side (as if drunk) or sitting at an angle such that it acts like a full-tail rudder, like this (over-dramatized):
...... _
......|..|
......|..|
|<::|..|::::::\\
......|..|
......|_|

Any more info you can provide, including photos would be most helpful.

Good luck.

Wings

[Hah! My first success at ASCII graphics...in only three tries!]

[2NG]

*****[Hah! My first success at ASCII graphics...in only three tries!]***** LOL.:D

Check your throws properly upon initial flight, as well, as range check. always check:)

[NYBackyarder]

I will post a pic tonight (at umm work ;))

The servo throws are good, and the arms are prependicular to the fuselage. As I was taking some photographs this morning, I think I noticed the fin section is slightly off. I also had the motor a bit off too. (Boy what a way to screw up the plane huh :D) So how would I go about correcting the fin?

I also devised a way of testing flight characterists before actually risking a crash. I hung a wire from a ceiling hook and suspended the plane by that (at it's CG point). Then throttle up. Sure enough, the plane reacts as it does in the air, and allows me to get a better look at what's going wrong exactly ( I suppose the next step is a wind tunnel, but I don't have a fan big enough ). Caveat with this approach is the room must be clear of obstacles (and people).

[NYBackyarder]

here is the pic

[Dave Robelen]

Hi Backyarder,
Based on the picture (very good idea) The fin is actually angled to the right, but the rudder is definitely showing some left. I would ignore the tailwheel if you canot change it, and set the rudder to center. It is also very likely that you will need the motor pointing slightly to the right. In general, biplanes tend to pull to the left when the motor is straight ahead.
Take care, Dave

[2NG]

NY,

Looks good, Man.:) Check throughly in the bench, and see if there is something hendering it to push and pull play.

[DougBinder]

You say it's pulling to the left but would it describe it better to say that it's rolling to the left? I ask because I wonder if the wings are warped.

Set the plane on a table and stand 5-10' away from it. With the plane pointed straight at you, aise or lower yourself until the trailing edge of the plane disappears. Do both sides disappear at the same time?

Doug

[NYBackyarder]

It definately doesn't roll. Just yaws to the left, the wings appear to be ok. I have had successful flights, just control is a bear (and being my first plane it has been *quite* a learning experience). I would have done a test this night (friday) but major storms came through - no flying tonight :(