Jim,
I've looked for hard data on the Madras tips for years and never found it. As winglets became mainstream (well after Madras tips came out back in the '60s or early '70s) there have been comments that Madras did their design just exactly upside down, but, again, I've never seen any data on how winglets would affect performance of a 150/152.
While in curious mode, it would be interesting to see a comparison of stall speeds with VGs versus Madras tips, taking into consideration weight of the conversions. I can't help but think that the VGs would win that one - but, that's purely opinion not backed by a lot of fact.
Best regards,
Rick
