For a slow flying "stick and tissue" aircraft an OS .10 engine will adequately power aircraft up approx. 50" wingspan if the wing loading is kept reasonable low, say 10-12 oz./sq.ft.

An excellent choice if you have some experience with stick and tissue models is Vic Smeed's Mamselle 52



You can order the plan from the [link=http://www.myhobbystore.com/]RCM&E Plans Store[/link].

About the maximum size for a OS 10 is the RCM [link=http://www.rcmmagazine.com/store/store-plans-catalog-tem.html?item=plans:PL-810&sid=0001Q3iX7bkKNxEqT0045Q8]Big Bird[/link]. This aircraft is a very good trainer with forgiving characteristics.

/Red B.