You bet I do Tony! The Challenge 1 was the only model I remember that was specifically designed for the OS geared 60. Was in many ways a model way ahead of its time IMHO! If not for the noise rules that came into effect shortly after OS released those engines, I think your Challenge 1 and the geared engine would have been the beginning of a new era for F3A.

I remember loosing my Tipo the morning of a contest back in the early 80's and you letting me borrow the Challenge 1 for the weekend so I could fly in the contest. It was a fantastic flying airplane!