Hello; just bought this thing and I don't have a clue. What kind of airplane is it? Thanks!

Not a clue!
What engine on that model?

Engine reads OS 10 and also 871. Airplane measures 56", wig measures 62"

Thanks.

I'm pretty sure that is a Peck Polymers Prairie Bird 50. http://www.peck-polymers.com/html/pprc.htm A former friend built one, he said it flew great as a trainer. I built a few of the rubber powered versions and flew in outdoor bostonian events. They fly so good, they can fly away.

Tom Nied is correct that it is a Prairie Bird, but that is an extended wing. The stock wing is 49" span with 3 panels while yours is much longer with a 4-panel polyhedral setup.

It was originally published in Model Builder magazine I think. They called it "Big Bird the ET" for some strange reason. I had one that I flew with an OS .10. I have photos, but they are not digital. I'll try to scan one. I covered mine in red transparent. It was really pretty like a Seniorita or similar. I'm dying to try it as an electric plane.

Scott