HP-24 Project

Over the Thanksgiving holiday I laid up test parts of the turtledeck and the two forward bulkheads. None of the parts came out nice enough that I'd send them to a customer, but all were good learning experiences.

I also put up the wall brackets for the wing plugs and got the plugs up on them. So now I can take down the old pod racks and reconfigure the shop floor so that I can have both fuselage shell molds in the heated bay at once.

The pictures pretty much tell the story:

This is what 125 yards of 7725 fiberglass cloth looks like.

Here I'm laying a swath of 7725 into the turtledeck mold to get an idea what size layers to cut from the roll.

Here I'm cutting the two +/- 45 plies for the turtledeck.

Now I've got all five plies in and saturated with resin.

And here it is a day later, popped out of the mold. I got a good release and a nice shiny surface. There are several voids between the glass and the gelcoat, and the lamintae didn't follow the contour of the canopy frame recess as well as I'd want. It's OK for a test piece, and it looks nice on the fuselage, but going forward I'll need to bag this part in order to get flight articles.

Now I've set the part loosely in place on the fuselage plug. It looks good, and will fit even better with a little more trimming and with it pulled down into position and secured with screws or glue.

Here I'm test-bagging the nose hook bulkhead.

Here's the part after curing and unbagging, and with the nylon peel ply half pulled off.

And here it is with the peel ply off, but before I've trimmed off the hat brim. The red lines mark the ply orientation for reference. In production parts, I wouldn't use a red marker like this, since it probably affects the resin properties. Also, I'll need to add more plies when I next bag this part, since the bagging compacts the glass more than I expected.

This is the canopy piot bulkhead mold, being readied for a test part. The white stuff on the pivot ears is some flox that I buttered in for a quick-and-dirty reinforcement. Based on the way this part came out, I'll omit the flox on future pulls.

This is the way I left the part on Sunday afternoon. When I pulled it Monday evening, I got a good release, but again an unsatisfactory part. This time the big issue was the inflexibility of the nylon bagging material. Going forward, it's clear that I need to use the stretchy bag material on these deeply-dished parts. That will let the bag pull into the corners better for a more conformal layup in those areas.

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