RE: Building the Yak 54 - 79"
Mr Bigg your correct. There are actually two ribs there the root rib is ply and the inner rib is a thick slice of balsa during the building you laminate the two of them together forming a strong, light, single root rib.
Squirrlcommander, the Saito 180 should be OK you may not be able to blast off out of o hover but it should have enough power for a decent 3-D plane..If you dont have the engine yet I would recommend a Moki 180-210 or a YS 140-160 over the Saito 180, but if you already have the Saito go with it...