I believe the design was discussed on Paul Lamar’s list and a couple at least have been made. It was run on one of Tracy’s engines at Shady Bend. They have at least two sizes, and different outlet configs. I would call Ed and discuss them with him….or call Tracy. I wasn’t there to see it in action. When I talked to Ed, he said the test versions were not fab’d of the correct grade of ss and he was upbeat about them, as he saw his work in action.

BTW, this is how the combustion chambers of jet engines are cooled-non combustion air is ingested that sticks to the outer walls of the ss chambers (a very involved physical process is involved in making this happen, and it is basic to the most advanced designs coming out), and keeps the ball of flame away from them…..also this principle is used to reduce sound effects in the exhaust outlet nozzle by routing cool air around the hot center (reduces the ripping noise quite a bit)……..fwiw. So maybe it will work on the rotary…….

Marc Wiese