Justin wrote:
>>I have already tapered my spars for the HS but I havent got the angle in
there to match the airfoil. Is it too late to make it match properly?>>
What I did was to take the angles off the airfoil templates and calculate
the dimensions of a right triangle with the back edge of the HS spar as the
forward point and the front edge of a copy of the tapered spar (that
mirrored the HS spar) as the rear point, but taller by the amount to give
the correct angle(slope) when laying a sanding board on it. The base leg of
the triangle depends on the distance between the HS spar and the taller copy
of the spar. The additional vertical height on the rear copy is based on
this distance. I then covered the top of the HS spar with a very light coat
of dark paint. Clamping the HS spar to the front of a 1x3 and the taller
copy to the back side, I could lay a sanding board on the two surfaces and
sand the HS spar until the black surface disappeared. You can see the
black surface disappear from front to rear as you sand along the length of
the spar. This gave the exact angle I needed to match the airfoils and when
I slipped the airfoils over the spar, there was indeed a match. Using this
jig method made the sanding go fast, smooth and accurate along the length of
the spar. The only thing is you need to cut 3 different tapered rear
sanding "jigs" since each of the spars (two in the HS and one in the
elevator) are of different height. But since the spar is symetrical, you
only need to do a half length for the taper copy and flip it over to sand
the other half of the HS spar. It would be easier to draw this than
describe it..if you need to know more, please send me an e-mail off line.
|---------lay sanding board on top and the slope should
be the angle you need.
\/ |
| <HS Spar | <----taller "copy" of spar
|___1x3______|
r/Bernie
Lexington Park, MD
KR2S Builder
http://mywebpage.netscape.com/n2w6
