Cowl Rework

Well, I started over again. I did not have the splines in the correct locations. I could have made it work but I was determined to figure out how to place the splines properly.

I decided to build the shape out of foam while using the splines as a guide. Having it made of foam meant that I could screw it up and still go back and try again. This was the 4th attempt at getting it right. The sad thing was that I almost had it right on the first three tries. All of the reworks, while time consuming, will pay off in time saved on future projects. For reference, to spline, tape and prep for glass, the spline method took about four hours. Shaping the foam for the plug and getting it prepped took about 20 hours.

I am going to do a step by step write up on placing splines (with lots of examples of what not to do ; ) For now, here is how I used the splines as a guide for shaping the foam.

First I used a spline from the split line of the cowl to the spinner and made a cardboard template. I then used that to cut a piece of foam to the same shape and glued it to the cowl and spinner. Next I used the splines to rough out the angles that the splines would meet the leading edge of the cowl.

From there I stacked small strips of 1/2" foam and built it up and aft.

I again used the splines to guide the shaping process. After a few reference grooves were cut, I sanded between them to get to the final shape. Many long and tedious hours...

After lots of hours of sanding and shaping, the plug looks like below. I stuck mock inlets on it to get and idea of how it would look. I'm not totally sure where they will be or their size yet. I have to get the final part to assess what my best options are for avoiding the exhaust pipes wile still allowing for a properly shaped diffuser.