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Old 09-29-2012, 01:23 AM   #16
Don Stackhouse
Don Stackhouse
 
Join Date: Sep 2012
Location: Bradford, Ohio, USA
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Club: Flyn' Wolverines, UVFF
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First of all, the Chrysalis series fuselages do not have stringers in the nose. From the nose to a little aft of the wing trailing edge they have 1/8" lite ply doublers in the fuselage sides. The sides have a balsa sheet outer skin outside fo the doublers. The belly is balsa sheet, but there is a birch ply skid plate under the nose and wing, which also acts as a tension member in the case of "dork" landings. It's all pretty durable.

The recommended method for xtending the nose involves a long scarf cut in the doublers, angling forward from just in front of F2 (the wing leading edge bulkhead), about 30 degrees below horizontal. After splicing in the extension, reinforce the two splices with 1" glass tape and epoxy on the inside faces of the doublers. The balsa outer skins will reinforce the outer faces of the doublers sufficiently. Running the splices in this manner minimizes the factors that would encourage buckling failures on the top edges of the sides, or tension failures on the bottom edges.

We use the same balsa pieces and ply belly plate in the electric as in the sailplane kit, so these will be long enough to cover the extended area without any additional splices. There are some splices in the balsa pieces, but those occur back under the wing in a way that is not structurally critical.

While the lighter motors in common use these days are a contributing factor, the biggest cause of C/G problems is poor workmanship in th tail section, particularly using too much glue, and not enough sanding in the corners.
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