Comment

Comment by Bob McDonald on May 13, 2012 at 7:32am

If the aircraft heads left on take-off as power is rapidly applied... this is normal. Apply 1/2 right rudder until airspeed increases and rudder authority increases with the airspeed. If flying solo and it feels like the left wing is "heavy"... a slight tendency to turn left.... this is normal. Flown dual it should be nuetral. I use the right wing locker for baggage or keep the right leading edge wing tank full to off set this "heavy left wing". I also have electric trim on the right wing. Lift your tail on a saw horse, clamp the rudder pedals together straight for level flight.....look at your rudder.... is it straight? It should be slight "left rudder". Does the taildragger version have a stub nose tube (cut off nose gear tube from tri-cycle gear)? If not what holds your rudder pedal forward?

Comment by steve methot on April 29, 2012 at 1:10pm

Thanks Jerry. I had a look at the builder's drawing and the normal offset angle of the engine (crankshaft line) is 3 deg to the right of aircraft centre line (causing a nose right correction), much the same as on a Cessna for example, where the vertical stabilizer is also offset to cause a nose right correction. Do you have any advice on how to measure the offset angle of the engine? From the symptoms, the offset angle would have to be more than 3 deg. Correct me if Ia am wrong but I believe the engine mount (rack) come already welded from the manufacturer and should not require much adjustment to fit on the airframe. Too bad I did not build this aircraft. Hope you can help.

Thanks a lot, and I enjoyed the video you posted.

 

Comment by Jerry Latimer on April 27, 2012 at 9:13pm

Could be the angle of the motor mount.  Does the plane try to go left during the takeoff roll when throttle is applied?  In flight with everything in trim (don't change the pressure on the left rudder), does the plane go right when throttle is reduced to idle?  Could be the angle of the motor mount is off.

Comment by Paul Saccani on April 22, 2012 at 3:03am

I've never seen a tail wheel version up close, so everying I am saying is speculative. If it has rudder pedals like the nose wheel version, there has to be something to tie the left and right pedals together and hold them in a nuetral position.  There may be springs in the footwell to do this.  In the tricycle version, the nose leg in front of the firewall to does it, with a cross tube resting in a notched gear stop at the bottom, with rods connecting the pedals to it to maintain the nuetral position.  As the gear is pushed down by the bungee, it centralises on the notches, which is, of course, the condition in flight.

Adjusting the tie rods between the pedals and this cross tube adjusts the nuetral position.  You must have a tie between the rudder pedals at some point, and somewhere, you must have something to bias the rudder to nuetral.  Have a good look in the footwell, and see what is stopping the pedals from flopping to the rear of the aircraft.  Chances are, you will find a couple of tie rods, and with any luck, they will be attaching to something to bias the nuetral position, and it will be a matter of adjusting the tie rods to change the nuetral position.

Good luck.  Perhaps you might post some pictures of your set up?

Comment by steve methot on April 17, 2012 at 7:21pm

Thanks Phil. Well, it will probably be a trim tab as you mentioned. I will take some measurements however to confirm your suspicions.

Comment by Phill Barnes on April 17, 2012 at 6:25am

Hi Steve

It does sound a bit unusual for bad yaw in all modes of flight. Does it do it on a glide approach?

I suppose it could be one or a combination of a lot of things. Probably start by checking the side thrust of the engine whichever it is and run a string line under the fuse from center to center and take some measurements. If it is not that, measure from the wing tips back to a center point at the tail and from the h/tail tips to a foward center point.

 

Hope you find the problem and that it is a simple one to rectify. If you cannot find anything wrong, a fixed trim tab maybe in order. 

 

Good luck.

 

Phill