UH-18SP Thrust Duct Construction - Page 3

Here are all the pieces sanded.

Next we had to cut slots in the foam, these slots are cut so that you can wrap the foam around the disk without it breaking. The jig we made has a 1/2" thick base on it so that it will cut all the way through except for the last 1/2".

Here is the jig that we made to mark where we should cut the slots. It is just a piece of scrape foam that has the same arc as the duct foam does and then there is a piece of wood screwed to the top of it.

Here we are test fitting the foam, it turned out to wrape around the duct almost perfectly.

Next we had to glue the foam to the duct. We cut some pieces of wood that we screwed to the inner plywood ring which held the foam on and then we added the red strap to pull the frount down. Also the very edge of the foam didn't want to stay down in a few places so we made some PVC clamps. They are just 1.5" long pieces of PVC pipe with a slit cut in them, we used some of our old vacuum bagging pipe to make these.

Here it is glued on to the duct.