Lift Strut Fairings

Started work on the fairings that cover the lift strut forks and fittings at the wing.  Here is what the originals looked like:


Notice there are only three in the picture, and I need four. So I set about making several. But first, here are some pictures of the original on NC12350 at the factory:

original-lift-strut-fairings

Here is a better picture of how they look, this time on Cam Blazer’s Model 90A:

cam-blazer-strut-fairings
I took one of the three I had and stripped it, planished it smooth, filled that gap where the strut fork goes, and mounted it on a solid surface.  Then primed and painted it:

original-ready-to-mold

Here is the same piece shown above, but just flipped upside down to show what the other side looks like:

lift-strut-fairing-in-mold-1

At this point it is ready to make a mold.  Living in a rural area, I have little choices for mold material, so I picked up a 60 lb bag of cement at the local hardware store.  I made a frame to go around the original piece.  The original piece and the frame were waxed and then covered with a thin layer of vaseline.  Then mixed and poured the concrete into the frame (on top of the original piece).  Let this dry for 2 days and then un-molded it, leaving a perfect impression of the original piece.

Here is the mold, a piece of aluminum and the starting hammer of choice:

concrete-fairing-mold

I cut a piece of wood to screw onto the top of the frame and aluminum, that outlines the shape to be hammered.  The screws help hold the aluminum in place:

aluminum-in-concrete-mold-ready-to-hammer

This is 3003H14 that had been annealed in the area to be shaped.  After about 10 minutes of hammering, here is what it looked like still in the mold:

lift-strut-fairing-in-mold-2

And here is that same piece after being removed from the mold:

strut-fairing-shaped

I’ve made two of these so far.  Some planishing with a tear drop dolly and slapper.  They are going to work out great.  I’m thinking about making another mold so I can make some more.  I might try making the mold out of Hydrocal 40, a US Gypsum product that is 8 times stronger than concrete, has little or no shrinking when drying, and has been used successfully by hot rodders to make some body panels.

 

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