"The aircraft has an irritating left turn in it when flown solo and slight left turn with two up. When trimmed out cruising straight and level the ailerons are close to even with the wing tips and the left flap is noticeably lower relative to it’s aileron than the right side, which is almost even with the aileron. I think if I can rig the left flap up even with the aileron it will help cure the left turning problem and be less drag.
I thought I might get a new flap hinge arm (FL16) on the left and with the aircraft supported and flaps up in the desired position I could drill new holes thru the lugs on the tourqe tube so the left flap retacted position matches the right. Will this work or is there a better way?"
Thanks, Kevin Klinefelter 03/09
After flight testing a number of these aircraft the advice/concerns of all who have answered are sound.
My tips for in house use are pasted below, this presupposes that you have accomplished the Annex E properly, checked the engine and systems for safety etc.
Preflight Rules before you fly:
Rule 1. Check the incidence with a digital level at the root and the tip. Should be within .1 degree. Some of the tips are off a little.
Rule 2. If a mono, support the aircraft and retract gear and flaps, if tri-gear, retract the flaps. Sit behind the aircraft on centerline and look at the trailing edge. Move your head up and down until you can see the shadow line of the lower surface. Look left and right. The shadow line should be even on both sides. The mean aerodynamic chord is near the flap/aileron junction. Your outriggers will spoil your view, but at that point the left and right wing shadows should be dead even. This checks the wing is square and the incidence is correct. Some flaps have a little play and will droop under gravity, but fly up when airborne. Use a stick with very light pressure to hold them in place.
Note: Why use your eye, because the eye is a superb level and square indicator, not suspect of measuring methods.
Rule 3. Check the tail surfaces are square to the wing and the rear fuselage is not twisted. Both stabs are exactly at the same incidence. Two degrees off on the stabs is like 1/8 aileron deflection.
Rule 4. Check the engine offset is per the manual at right thrust 1 1/16 inch offset to the firewall.
Rule 5. Check flap hinge coves and wheel pants for square. Remove if not aligned properly.
From my experience, the left roll is due to pilot weight. Higher thrust engines and CS props will add P factor even at an alpha of 2-3 degrees. Most planes need slight right rudder. This is easily trimmed by shortening the right rudder spring one or two links or putting in a cable shortener as depicted in the manual on the one side. (Trim tabs are ugly when stuck on a beautiful airplane and emphasize that there is a rigging error.) So preserve your ego and let the spring do the work for you. Yes I designed a rudder trim, and no I won’t tell you but you can figure it out from above.
Any roll with a drooped flap in flight needs to be compensated for, so jumping ahead:
Roll trimming during flight test:
Any roll corrections need to be done with the ball perfectly centered. Most EFIS ball indications are not as good as a good old fashioned ball and a distant cloud.
Center the ball first.
Move aileron to stop the roll and re-center the ball. Note the aileron deflection by checking stick free with deflection required. Land.
Note: By this I mean hold the stick for level flight, then release and note the movement of the stick. Reapply the stick deflection and note how much deflection stops the roll... Look outside too.
Provided the aircraft has even stabs, proper incidence and the flaps are even, proceed to:
Adjust the flap which is up too far with the set screw in the baggage bay (Custom Flight Mod) or by adding a shim to the back of the baggage bay and the flap tube through the hole in the side of the aircraft with thin wedges to shim the flaps 1/32nd of an inch to correct roll. Right flap down rolls right. Go fly. When roll is cured you may need to adjust the aileron to match. But wait, most likely, then it needs the flap to be trimmed again for less deflection due to the aileron trimming, or because you made the airplane with very little friction in your roll system, you may see both ailerons now evenly up or down as appropriate. Go fly again. Test trim, then re-do stall series.
If the wing tip is off, and/or an aileron tab is needed, re-contour the aileron. To do this, sand one inch back on the lower trailing edge of the aileron which needs to fly up and add filler (Evercoat Rage works great) to make a wedge that tapers from zero to 1/16 of an inch along the full span. Think of it as a long wedge of nearly no weight. Go fly. Land and sand, then go fly until it is trimmed. Paint as required. Makes a virtually invisible aileron trim tab and the thickness is very difficult for the untrained observer to catch.
Enjoy making your plane perfect, it is worth the effort. I never get a chance to do my own.
Bud Yerly Custom Flight Creations