Hello Jason,

I did some temp reading when I was setting up my SimJet2300 and dual wall single pipe. While the engine was running the outer wall of the pipe did not exceed 41deg C . This was far cooler than I thought. However the temp did rise to about 75deg C straight after shutdown. This would suggest that the use of a cordless blower after shutdown to keep air flowing through the airframe to be a benefit.
One interesting reading was that while the test bed was sitting out in the sun without the engine running the temp reading was 49deg C.

Regards
Bruce