Message-ID: <000f01bfc581$e749f4e0$73b188ce@pavilion>
From: "J. N. Cameron" <toucan@The-I.net>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: ES tail twist
Date: Wed, 24 May 2000 08:13:46 -0500
Mime-Version: 1.0

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    On my first ES, the vert stab skin did have a twist to it, so a fairly
elaborate procedure had to be followed to get a straight tail.  I cut a
piece of 3/4" plywood about 36" long by 2" wide, then, using a cardboard
template, cut out one side of the plywood piece to match the profile of the
vertical stabilizer about half way between the HStab and the top of the
VStab.   This plywood piece was then fastened to the VStab with screws and a
little cyanoacrylate glue.  The piece when attached was parallel to the
floor, and stuck out about a foot behind.  To align the tail, I made a
little wire loop sight at the back so that I was sighting from the midpoint
of the where the rudder post would be.  That is, if the rudder post was 4"
wide at the height of my jig piece, I taped the little loop sight in place
2" to the left of the TE of the VStab skin.  For the second sighting point I
drilled a small hole in the LE of the VStab, trying to get the hole exactly
centered.  What we're going for here is a sighting line from the rear loop
sight, through the hole in the VStab LE, to the top of the firewall, so the
drilled hole needs to be a little below the level of the jig piece.
    Next step is to find the exact center point of the firewall, then just
push an 8-penny nail into the honeycomb core far enough so that it sticks up
as your sighting point.  What I did next was to tie a 1/8" nylon cord around
the aft-most part of the jig piece, then find something immovable nearby to
tie it to.  I found I had to pull it considerably to the left in order to
pull the sighting point to the middle; i.e., without the jig arrangement,
the tail would have pointed about to the front left corner of the firewall,
instead of to the center.  I left the tension on the jig piece until all of
the spars, ribs, spar caps, etc., were completed.  Frankly, I can't remember
if I left it in place until the VStab was closed, but I don't think so, as
some of the screws holding the jig piece were put in from the inside.
    That wasn't the end of the tail problems, actually.  The shape of the
VStab was not symmetrical; i.e., if you cut a cross-section in a plane
parallel to the floor and looked at it from above, you'd see that one side
was considerably less convex that the other.  In other words, one side was
flatter than the other.  The greater curvature of one side also meant that
the skin didn't fair back to the rudder properly, so a large area had to be
micro filled and covered with glass to get a smooth airfoil.  Shape of the
rudder wasn't symmetrical, either, and getting proper gaps between VStab and
rudder was a long, tedious deal.

Jim Cameron,  ES #2 in Progress (no tail yet, so ???)


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