Larry Champion RV-8 (Slow Build) - Page 4.
October 16, 2008: I went over to help Larry
Champion again with his RV-8 for a couple of hours this past Thursday evening. The
task was to check the alignment of the main landing gear legs and their axles to check for
toe-in or toe-out. When I began to suspect a problem with a "twist" in the
LEFT landing gear leg, I got the idea of clamping a piece of aluminum angle to the gear
leg near the axles. The black marks are 12 inches apart on this angle.
Over on the other angle, the angle length is ONLY 12 inches. By measuring
the distance from the forward end of this angle, to the forward black mark on the angle
above, then comparing that distance with the aft end of the angle with the corresponding
mark on the angle above, the proof of a twisted landing gear leg was confirmed.
And here is the result of the error showing a toe-in condition on one axle
versus the other axle being perpendicular to the center line of the fuselage. This
first photo is of the axle with the problem. The string is not parallel with the
wooden block or the axle.
Over on the side that is true, the string follows the face of the wooden block
and is parallel to the axle itself.
By the end of the measurements, it was determined there would be no drilling of
gear leg attachment blocks tonight. A call to Van's Aircraft tech support would
follow the next day.
October 18, 2008: Saturday comes and I am now armed with information from a conversation with Van's Aircraft tech expert, Ken. He was amazed that when I helped Wendell measure these same parameters that no correcting "axle shims" were needed on Wendell's quick-build kit. Ken liked my idea of the two clamped aluminum angles to determine the twist error in the landing gear legs.
For this photo, we put one AN-4 spacer washer on each of the forward bolts that
hold the axle to the gear leg. The thickness of that washer was measured and the
spacing between the forward and aft bolts holding the axle to the gear leg. A quick
arc tangent calculator entry showed the angle to be corrected by about 2.6 degrees.
The result was a "banjo tight" string across the face of the blocks on
both axles when they are both equidistant from a center-line reference point near the tail
of the fuselage! Victory! At that point I went upstairs with Larry and had him
log onto the Van's Aircraft web site, showed him the 1-degree and half-degree axle shims
made by Van's to correct the slight twist errors in the RV-8 gear legs. He ordered
TWO of the 1-degree shims and ONE of the half-degree shims to correct for the twist in the
LEFT landing gear leg. When they arrive and I return from my current road trip, the
landing gear will get a final true alignment and the mounting holes will be drilled into
the fuselage strong points of steel and aluminum of the gear leg towers.
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