I tried OTF for a year and found it to be all over the place, topic-wise. I guess it's hard to focus, but I would have preferred a magasine that had issues devoted to specific topics. Over the year I subscribed, I can't say any of the articles really interested me. I felt it was too pricey for what I got out of it.
For Canadian content you might try Journal of the Canadian Aviation History Society (
www.cahs.com). However, most of their material is either civilian or WWII historical. Their early issues had more WWI material.
Miles Constable