Ok I found the magazine I was remembering from. It is Model Airplane and its the DEC 2000 issue. As it states the record IS 150.1mph set in 1984. Another good reason a turbine has not set it is because its not even allowed! The rules state an engine limit of 10cc or 0.61ci. These are FAI records. Sorry I was alittle off the mark but atleast I found the magazine to back up what I wrote. Oh yes I have heard of the slope soarer doind 237 but its still not an official record. The person who wrote this article actually holds 23 world records and if you would like to write him at 2001 Norvale Rd., Silver Spring, MD 20906 he mentions that he would be glad to help with any serious speed record attempt.
I like the comment of 1950 Germany...good laugh.