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View Full Version : Wing Levelers and Rudders



Chick
10-27-2011, 07:45 PM
Can anyone tell me anything about wing leveling auto pilots and planes that need a lot of rudder input? I am interested; but, don't have a clue if it will still require constant rudder inputs in cruise. In cruise the rudders require a bit of attention and I'm curious how it would react to a wing leveler. Thanks, in advance for any help.

Eric Page
10-27-2011, 08:09 PM
I've flown one big, stable airplane that's a rudder hog: the de Havilland DHC-8. It has a 2-axis autopilot, a yaw damper, and 3-axis electric trim, but you still have to use the pedals. Adding power causes yaw to the left, decreasing power causes yaw to the right. At low speeds, the effect is dramatic. During climb and cruise, pretty much everyone adjusts the rudder trim to keep the ball centered. In descent, it's a mixed bag: some adjust the trim (and then readjust it every time they level off and start down again), and others simply pull the left engine back about 20% lower than the right (prop RPM remains synchronized).

My point is that if an airplane requires your attention on the rudders without an autopilot, nothing will change if you install one. The wing leveler will free your hands to write down clearances, fold charts, eat your lunch, or whatever. It won't change anything with regard to directional stability.

Interestingly, some modern jet airliners require almost no rudder inputs. Long John Silver could make a crosswind landing in an Airbus. Aaaargh!

FlyingRon
10-28-2011, 06:22 AM
Most planes are pretty stable. If you level the wings even if there is a little momentary loss of coordination it settles down quickly. If not, you add the third axis (yaw damper) on to the autopilot. I've only got ailerons and elevator connected to my plane and it's never a problem.

Chick
10-28-2011, 07:34 AM
Thanks guys, as a newbie (pilot and owner) I appreciate the knowledge and tolerance. This forum is great for finding answers. Give me 20 years and I can return the favor!

Hank
10-28-2011, 10:32 AM
My wing-leveler has four servos: one for each aileron, and two in the tailcone. It will hold heading very well, for hours on end, requiring only slight adjustments as the winds change. Rudder is, of course, required for turns, high-power situations and around the pattern.