RE: Hergett TA 152 H
Yes, it was balsa with a foam core wing. Used the house of balsa turtledeck canopy from their FW 190 kit. The Hergett designs were the best designs of the time I believe with the use of the Eppler 203 airfoil. The Mustang and then the TA 152 dominated the early events at the inception of the RCCA.
Steve Hergett also had an ME 109 T, which was the last combat design he had as far as I know. It too had a long, high aspect ratio wing. A huge benefit in combat.
I have actually located a source for plans. While this design is not as suitable now (because of durability issues), it would still fly with the best of them I believe. The dominance, and prevelance of the TA 152 has a lot to do with why event 2548 was created.