[kurlannaiskos]

Originally Posted by Franek Grabowski

I think that there were full metal Yak-9Us and it depended on production batch/block.

NO !
much of the Yak-9U program was 'stolen' from the Yak-3.
this means wooden skins for the wings and a rear fuselage made mostly from wood.
(both the skin and the structural stringers)

the Yak-9P has a wing with metal spars and skins.
the first 29 or 30 (one serial number is repeated(?)) Yak-9P's has wooden rear fuselages, the ex-Bulgarian machine currently on display at Monino is one of these.
the wooden rear fuselage confuses a lot of people and they often mis-label it a Yak-9U.