>  I find the wingtips on my son???s  project more than a bit odd.

++++++++++++++++++++++++++++++++++++++++++++++++++++

If you were air, would you want to meet that wing 
tip face to face?  It looks like a real drag 
bucket.  You can mount lights on a Horner tip 
just fine.  https://dl.dropboxusercontent.com/u/32133949/100_5553.JPG

When building, I was concerned on getting two 
identical tips.  The method I used turned out to 
give me a perfect Horner tip. Is that the way they originated, by accident?

The method I used was to glass the top surface of 
the tip first.  Straight sand the tip to 90 
degrees of the forward spar.  Flip wing to bottom 
side up and draw a line inboard of the tip and 
parallel to the top.  I used a line between two 
foam blocks 4 inches inboard of the tip.  I think 
5 or 6 inches would have been better with the 
thick RAF48 wing.  Use the hard glass tip on the 
top surface of the tip and the line on the bottom 
to straight sand the tip.  The shape changes as 
the thickness of the wing changes but it remains 
a straight line.  When sanded, put a small radius 
on the lead edge (I used a 4 inch mixing cup) and 
a smaller radius on the trail edge ( I used the 
rounded corner of a tape measure body).  Hand 
sand the lead edge to a nice radius and put the 
radius on the very thin trail edge.   When 
finished, apply glass.  It is a very easy process 
to duplicate and when finished I realized I had 
created a perfect Horner tip.  The reason the tip 
works is because the high pressure air on the 
bottom has difficulty making the very sharp 
corner to reach the low pressure on the top of 
the wing, basically performing the same function 
as strake tip you see on airliners, etc..

Larry Flesner 


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