Paul,

Mike Selby has been working on an F-111 with a similar configuration, he originally built it as twin-turbine and then converted it to a single asymmetric setup. See this thread:

[link=http://www.rcuniverse.com/forum/fb.asp?m=8933867]http://www.rcuniverse.com/forum/fb.asp?m=8933867[/link]

In his case the engine outlets are much closer to center, so you would probably have to consider if it would work for your SU-27. Mike is a great engineer and a master builder, and would probably welcome a question or two from you.

Dave McQueeney