Message-ID: <39B50466.80388485@regandesigns.com>
Date: Tue, 05 Sep 2000 09:34:14 -0500
From: Brent Regan <brent@regandesigns.com>
To: Lancair List <lancair.list@olsusa.com>
Subject: RE: IV-P landing gear uneven when "in the well"
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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It should be no secret to anyone who has spent some time rigging a IV
fuselage that it is not bilaterally symmetrical about the longitudinal axis.
In some places the variance is as much as 3/4 of an inch. When I established
the datums for my pre fast build fuselage I had a tip to tail external
centerline datum located off of the mold fiducials and an internal "cabin"
centerline measured off of the vertical internal walls. I used the cabin
centerline to locate the cabin elements and controls and the external
centerline to locate the wings, tail, engine, etc.

If the gearbox is built perfectly and located on the external centerline of
the fuselage, the wheels, when retracted, will not be equidistant from the
sides of the fuselage as the fuselage, at that point, is not equidistant
from the centerline. The correct thing to do is to shim the wheels and trim
the gear doors so that gear retraction and extension is smooth and the
clearances are adequate and symmetrical. For those of you who find shimming
aesthetically unpalatable, I would advise that you get over it. Once the
plane is on the ground, the brake calipers hide most of your axle sins and
nobody but you will ever see the wheels in the wells with the doors open.
Spend your time getting the extension and retraction working smoothly.

IMHO, re-maching the trunion block is a bad idea as that has the potential
of creating a completely new set of problems including having to relocate
the actuator mounts, the up stops and the down stops and messing up the toe.

One other thing to remember is that, the preferred tire, Goodyear FC-IIs
have a different, fatter (flatter) profile than the McCrearys (sp) that come
with the kit.

Regards
Brent Regan

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