Dominator Rudder Trim Tab

[GyroRon]

I wonder if your upper tail brace is true... if the tail is canted on top to one side this could cause problems

[Penguin]

Ron - Good thought. I'll take a look at it this morning.
I preflight it every time since I've seen the bolt in the cheekplate fail on another machine.
But I'll take a look from a different perspective.

[NoWingsAttached]

I wonder if the engine is pushing straight ahead or if it is pushing to one side. Sounds a bit like the engine isn't lined up with the birdie.

[phantom]

it could be something up front creating a sideways pressure, at one time I put the body on a gyro and did not need the rudder offset any more, without the body it needed the rudder offset, turned out that the body was not lined up with the keel.

Norm

[GyroRon]

So Larold.... did you fix it?

[Penguin]

Ronita - I haven't yet found anything to fix.
Touched all the hardware - everything is in good shape, tight, and straight.
Gerg mentioned engine alignment which is a bit challenging to measure. I figure the spark plugs are a close approximation to crankshaft orientation. The plugs line up well with a plumb line at the pitot, so I think that's fine.
As we discussed, the yardarm is offset to the left about an inch. I haven't decided on bending it as you suggested. Seems harsh. And I can't quite visualize how that would make much difference.
So I just went out and flew. It flies very nicely with some trim in the anti-servo tab.
Not 100mph yet as you predicted, but an indicated 94. It hustles right along.

[cburg]

I installed turnbuckles on my rudder cables this weekend to adjust out the uneven (1/3right) pedals during straight and level.

I first tried it with the rudder/pedals straight…as a baseline. It took nearly *FULL* left rudder to fly straight (big change from the 1/3 right peddle I started with).

Next I copied another Monarch’s tail preset angle, the typical 15ish degrees and it flew fine…with even pedals (with moderate left rudder pressure under high power settings). Noticeably less at low power settings.

Therefore, additional left return spring pressure will alleviate some of the needed left pedal (enough to fly straight at idle, in addition, trim tab will be necessary to take care of the high throttle settings (or angle the thrust line like I do on my trikes).

[cburg]

Originally Posted by NoWingsAttached

I wonder if the engine is pushing straight ahead or if it is pushing to one side. Sounds a bit like the engine isn't lined up with the birdie.

Correct…the thrust is not even (sometimes). As a Multi-Engine Flight Instructor this is a major topic learning to fly flying light twins with a critical engine (not a Duchess or Seminole…for example).

Here is info and links:

CRITICAL ENGINE

The critical engine is that engine whose failure would most adversely affect the performance or handling qualities of the airplane. The critical engine on most U.S. light twins is the left engine as its failure requires the most rudder force to overcome yaw. At cruise, the thrust line of each engine is through the propeller hub. But, at low airspeeds and at high angles of attack, the effective thrust centerline shifts to the right on each engine because the descending propeller blades produce more thrust than the ascending blades (P-factor). Thus, the right engine produces the greatest mechanical yawing moment and requires the most rudder to counterbalance the yaw.

http://www.glenndale.net/flight_trai...ight_Twins.pdf

http://www.airliners.net/aviation-fo...ead.main/7660/


Regards,

Chuck