A few years ago, I went through a " delta phase " and built several coro delta winged planes much like your disc plane. They all did roughly the same maneuvers, the pirhouette, incredible flatspin, good hover, etc.

After reading this thread, I decided to build a round plane, but I wanted to build it from balsa. I decided that building a round frame would be a lot of work... so I thought, " Hey, why not a SQUARE plane.... ? "

I had no idea how to balance it so I sought out the advice of renowned model dude, Dave McDonald.
We kind of decided that it needed to balance around 17% of chord. Next, I slapped a prototype together from coro for testing. I do mean " slapped " too. I didn't put any extra work into it at all. Figured I'd just fly it enough to get the CG checked out then build one from balsa assuming it worked out ok.

I'm very happy to say that it worked out GREAT and it seems even more stable than a delta in high alpha. I was able to pirhouette it even without a rudder. Same goes for tail touch hover. I should have some pics to post this evening. I couldnt wait for them to get on here and tell everyone.

Can't wait to see what a balsa plane with rudder will do !

Pics later !

Foamguy