Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Sat, 26 Oct 2002 21:20:46 -0400
Message-ID: <redirect-1845841@logan.com>
From: StarAerospace@aol.com
Subject: Re: [LML] Re: Gap Seals
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On several aircraft at Reno and elsewhere, sailplane gap seal material is 
used.  Trip tape also.  Any sailplane supplier will have it.

A few things should be considered before using it though.  First, if the 
aircraft requires the aerodynamic balance of the exposed portion of the 
control surface that the gap seal will cover, it's not a good idea to use the 
seals.  At least one aircraft I know of experienced severe handling problems 
when the aerodynamic balance was sealed.

Next, we have to worry about the things coming off.  They are quite strong, 
so if an end peels it will create a streamer that will bet the heck out of 
the aircraft until the whole thing departs.  Ask Dave Morss about this on the 
winning L-IV from 2000.  Put it on in small pieces, only a couple feet long 
each.  If a piece lets go, it will tend to depart easier instead of trailing 
and thrashing.  Pilots who have experienced this report it to be a religious 
experience.

Last, there is significant evidence that they really don't do that much.  On 
the drag reduction program for a major airliner, the addition of gap seals 
was quantified at 0.2% of total aircraft drag.  Not much for all that hassle. 
 Trip tape properly placed can make a lot more difference.  Wing fairings 
make far more difference.  I sell both, but I prefer to give people more for 
their dollar.

Eric Ahlstrom