I recently rotated the engine and changed the mount on the hovercraft I built. I did this to correct problems I was having with one of the belts coming off freqently.

After one short 10 minute test flight (had lots of problems), the heat from the exhaust cracked the fiberglass.

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I wasn't sure what to use to do the exhause but Zoama suggested a mandrel. I got one and am now getting ready to start the project. (I just want to make a little more progress on my CNC table first.

I haven't decided if I should use the second half of the mandrel to extend or redirect the exhaust.
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At a minimum, I figured I'd want to extend it with the left over straight piece. Not sure it I want to leave the bend in to point it rearward.