no matter what arf model you choose , you should allways have a real close look at visible areas and add more EPOXY glues plus Gussets ect. i have seen a Hagner 9 model actually loose its engine thanks to NOT ENOUGH Glue to the main engine bulkhead to fuse fixing points. when you do this you should also apply 2 good coats of thinned epoxy around all oil wet areas, before they get wet.