Hello; I bought a Top Flight Elder Bipe at a RC swap shop about 6 years ago, it had been well built and covered, but I (foolishly) decided that it needed ailerons on both wings. I removed the covering from the top wing and cut off the trailing edge. That's as far as I got on that project, as the problems of everyday life got in the way of my finishing it. I eventually acquired an OS 90 FS for it, but it reemaned hanging in my shop. This year, I gave it to a fellow flier who felt the need for a biplane. He is a superior covering guy, and found a few flaws in the covering, so he stripped all the covering off it and re-covered it with a fabric type covering. He is looking for appropriately sized iron crosses for it now. I can't tell you how it flies, but it looks to me that a slow running four stroke, like the OS 90 would allow it to float efgfortlessly at close to stall, a type of flying I enjoy. I gave all the plans and the building book to the new owner, but the book is available on line from Top Flight.