F
fly scared!
I'm puzzled by the way to join a composite box spar to the strut hinge fitting.
Unfortunately most composite wings are cantilevered so there's little info around.
If you do it in glass fiber you have to overdimension it for all the possible stress concentration around the hinge bolt.
If you do it in carbon fiber, it's brittle, corrosion prone, and you don't like drilling through it.
Ideally you could do it in alu and bond it around the caps and web, but the bond quality would be questionable in a one off.
Last crazy attempt: take a short tube and weld the strut flange on it; then glass it inside and outside with suitable resin, etching et c.; then build the spar around it, so that the spar plies bond to the tube glass. The idea being that the join depends more on the tube "encapsulation" than on the bond itself.
I know, there must be a standard (and sensible) way...
Unfortunately most composite wings are cantilevered so there's little info around.
If you do it in glass fiber you have to overdimension it for all the possible stress concentration around the hinge bolt.
If you do it in carbon fiber, it's brittle, corrosion prone, and you don't like drilling through it.
Ideally you could do it in alu and bond it around the caps and web, but the bond quality would be questionable in a one off.
Last crazy attempt: take a short tube and weld the strut flange on it; then glass it inside and outside with suitable resin, etching et c.; then build the spar around it, so that the spar plies bond to the tube glass. The idea being that the join depends more on the tube "encapsulation" than on the bond itself.
I know, there must be a standard (and sensible) way...
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