RE: Sonic
I recommended the 9x7 to keep the rpms down on the engine (rather than a 9x6). The LA46 is a good engine, but is by no means a serious powerhouse. Smaller carb, limited ports. If it revs too high, you will lose the bottom end of the rod or the pin. A 9x8 is a possible alternative. The 9x7 should keep it below 15K . If not, then move up to the 9x8 or 8.75x9W
I have not seen the Sonic in a while. The one I saw seemed to look ok covering wise. Not sure what was done to it. The airframe in general is just fine.
Covering was not an issue with the China Clipper- it was wood ARC