From: Fredmoreno@aol.com
Message-ID: <bc1c2f68.25093a9c@aol.com>
Date: Thu, 9 Sep 1999 12:30:20 EDT
Subject: Tape gaps on Lancair 2 place?
To: wrumburg@cdicorp.com, lancair.list@olsusa.com
Mime-Version: 1.0

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Bill:

 Responding to your question about tape on the 2 place Lancairs:


You are probably OK on the 2 place with the tape.  It is the higher true air 
speed, and particularly the rain that causes the problems on the 4 place.  My 
recollection on droplet damage is that it goes with the fourth or fifth power 
of velocity once a threshold limit is exceeded.  Thus once one crosses the 
threshold level (don't know what it is -- probably depends on surface, 
curvature, etc.) small increases in true air speed (not IAS) cause big 
increases in damage rate.

On thinking about it a bit more, it seems that if you were to use the 
polyurethane leading edge tape trimmed to appropriate width, it should be OK. 
 It is tough stuff, and speeds are probably low enough not to be a problem.

On Brent Regan's Lancair IV, he applied an adhesively backed anti skid layer 
on the top of the wing outside of the cockpit.  We flew through some clouds 
when trying to set the SFO to DEN record, and when we landed, there was no 
anti-skid pad left, just a thin layer of adhesive.  Otherwise it was 
completely gone.  We climbed out of the cockpit and promptly stuck to the 
wing.

 Others have told me that rain punches through the tape over gaps on the 
leading edge and then the tape peels back.  Rain and droplets are the big 
enemy.  The polyurethane tape is probably tough enough to withstand rain if 
the gap is not too great.

I think Don is right: limited drag effect on the 2 place particularly at 
cruise.  The bad news is at lower speed when the leakage through the gap 
becomes greater at greater angles of attack.  The Lancair IV is more 
sensitive because the flow at the wing fuselage intersection is very 
complicated (on all airplanes, particularly at high angles of attack) and 
easily disrupted.  And this location is frequently the origination point of 
stall (separated flow).  

I say go with the tape, and you will probably be fine.  Watch out for the 
rain.  But if the rain takes it off, so what?  Put on more tape!

Fred
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