MY 2c about flying wings
I think the more practical application of rudder would be to istead of using the conventionally, deflect them and use them as spoilers
I have flown the SPAGI or Coroplast Zagi. Swept flying wings have some interesting characteristics
Bad Looping(Unless you have unlimited vertical
Roll- not so hot
high aoa stall qualties-[:'(] I have had a zagi spiral in after a stall after a rol. it cartweeled on the ground-first time I have seen a zagi flat-spin
This is because swept-wings inherently have tip-stall
Note the Stealth bomber: for Yaw control it uses airbrakes at the wingtips... doesn't even HAVE a rudder. It uses elevons
I believ it does not use airbrakes, because in order to make them effective (get them out of the boundary layer, so that they actually contact the air) The penalties in stealth would be considerable, so it uses differential engine thrust for yaw
As for the advice to build fying wings out of foam, I agree, but coroplast is nearly indistructible, and you can build a zagi in 2 nights. Because of this, you can mess around with it more and try ideas.