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Re: REFLECTOR: NACA air scoop design, strake



  Two references I used were: Tony Bingelis, "Sportplane Construction
Techniques", page 199; and 12/91 Sport Aviation, page 72. As I remember, one
of the two resulted in a weird plot- I think it was the SA. I plotted the
results to CAD then sized the print as needed. The Sport Aviation article
does have a plot of the lip profile which I reduced on a copier then pasted
on fiberglass sheet to make a gauge.
  On the strake, I also used three coats. I also scuffed everything between
coats. On the second (Cabosil) and third (plain) I used a heat gun to thin
the resin and to try to suck it into pinholes. Even then I had problems with
outgassing and ended up sealing individual pinholes with drops of resin
after roughing them up with a pointed burr. Some of the Clark foam I've seen
had fairly large voids so perhaps I was trying to fill pockets in the foam.
I leveled the areas where the bulkheads and tape went by wetting with resin
then squeegeeing microglass slurry into the weave. I noticed that these
areas didn't outgas during the subsequent coats. I also used peelply with
the final coat to prep the bonding areas on the upper skin.  -Bill

prototype 'Super' Chipmunk N18EF
Velocity Classic RG N6098S in the works