Is there a major problem if you use a pipe that is oversized? IE running a 12 pound engine with a pipe for a 25 pound engine. Probably loose a bit of thrust due to no convergence but what about the cooling/heat issue. Thanks, Scott

Anybody with any knowledge??

Probably somebody like Tam would be the best to answer this - he's probably tried it on more than one occasion. Myself, I don't see why there would be an issue with a larger pipe. After all, the static thrust is greatest when it mounted externally without any pipe, right? I don't think that convergence is that much of an issue with turbine pipes because the exhaust velocity is so high to begin with - its more of an issue with DF's where careful balancing of static vs. dynamic thrust is necessary because of the low velocity and mass outputs...

Bob

You will need a lot of takeoff run.

I did this on an F-16. I was running a P-60 in a 120 pipe.
Take off roll was about 500ft and it was sluggish until after the second turn, then it began flying normally. This was at Greater SOuthwest last year, plenty of witnesses.

Replaced the pipe and it took off in under 300ft

Hi,

I tried this with a P-120 sized-pipe (well, that's what the mfgr. claimed...) and a Simjet 1200 a few years ago. The plane's performance was absolutely the same as when it had the smaller pipe (which collapsed) in it. In fact, the outer skin of the plane was cooler.

Thanks guys, I was looking for some real world experiences. I did notice during test runs that it ran very cool around the pipe. BTW it is a Maverick with a Wren 54 in it. It came with what looks like a 80/120sized pipe and and dont want to change it out if not necessary. The installed thrust test read 12 pounds-had 12.5 on the stand.Scott

I was wondering the same thing. I have a BVM Sabre with the BVM Turbine conversion kit and I want to fit a Wren 44 (instead of a 54).
The Turbine kit includes a pipe and associated bypass mount.
Anyone tried this?.

Regards