Message-Id: <3.0.3.32.19990115234345.02b652b8@olsusa.com>
Date: Fri, 15 Jan 1999 23:43:45 -0500
To: lancair.list@olsusa.com
From: Marvin Kaye <marvkaye@olsusa.com>
Subject: LC20 nose gear assembly drag
Mime-Version: 1.0

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
Hi gang,

Well, today marked sort of a milestone in the progress on my kit, as I
managed to install the primary nose gear assembly.  The GM15's are bolted
to the mount, the drag link and o/c links are installed and all my
measurements work out just as they're supposed to... with the gear extended
the strut is perfectly plumb and I've got precisely 8 degrees of forward
lean.  With the gear tucked up into the tunnel it's perferctly centered
(well, almost, it's less than .030" closer to the pax side than the pilot's
side as checked with an inside caliper) and I'm very pleased with the fit.
All is not warm fuzzies and sweets, though, as there are a few things that
have me a bit concerned, and I'm hoping that some of you might have some
words of wisdom regarding them....

First of all, the distance between the GM15 mounting pads on the engine
mount is about .040-050" less than what the strut/GM15 assembly suggest
that it should be.  IOW, I had to jam the strut up into the engine mount...
the fit is so tight that the strut would hang there without the need for
any clamps on the GM15's.  Needless to say, there is a bit of drag created
there and I'm a little concerned about that much load on those bearings.
Is this normal, or do I need to trim off the backsides of the GM15's and
remove that load from those bearings... all it would take is about
.015-.020" on each one and I'd still be snug, but not tight.

The next thing is the fit of the drag link in the nose gear tunnel between
the hard points.  In order to get it installed we found that we had to
apply a scissors jack to the inside walls of the tunnel to spread them
apart about .090"(+/-) so we could get it in without tearing up the skin.
When the jack was removed it took lots of wiggling and rotation of the drag
link to walk it into position between the hard points.  The drilling of its
axle hole went very smoothly, and it rotates just fine, but it is really
tight in there.  One concern is with it that tight, when the inside of the
tunnel is painted I'm going to tear up the paint job trying to move the
drag link into position.   The primary concern, however, is that this
additional drag may sooner or later cause the free fall test to fail.

I lifted the gear into the retracted position and allowed it to free fall
and it did so pretty snappily, all the way to the fully extended position.
With the strut hanging vertically it takes about 20# of pull on the hinge
point of the o/c links to move it to the 8 degree forward position.  I am
somewhat pleased that everything went together without the need for any
washers or shims anywhere, but by the same token, I'm concerned that the
tightness which I'm seeing may be too much of a good thing.  As my cousin
(and insightful building partner), Chip, said, "Don't forget, if it's loose
it isn't going to get tighter with age...", which is a very good point.  So
what say you, is this normal and I'm worrying needlessly, or is this too
tight and I need to make some modifications here and there?  I'm looking
forward to hearing any advice anyone is willing to share. 

    <Marv>