I have a total of 16 flights on my DolphinJet with the K140, each flight about 5 minutes. The the flights were flown at half throttle except for takeoff and a couple full throttle passes. After the last flight I pulled the turbine just to do a quick inspection of the airframe and found significant charring of the wood airframe structure below, to each side, and behind the turbine. This is not good...
I'm going to try install some heat shield tape to see if this addresses the issue, if it does not address the issue then I think the only other solution is a smaller turbine or a different airframe. If you are using a K140 I highly recommend pulling the turbine after a few flights and inspecting for burn marks on the wood structure.
I also closely inspected the exhaust tube and it is showing no sign of unusual wear so I believe the 25mm spacing (between the turbine exhaust ring and the exhaust tube) recommended to me is working on that account, however that's not going to suffice if the wood airframe burns up around the tail tube!
Has anyone else experienced this issue?
-Tom