RE: 1/5.3 Horten 229
Hi !
The Horten brothers have designed around 20 differents planes, in fact mostly gliders. All were flying wings and no one needed a vertical stabilizer to fly correctly and doing thermal circles.
At this time gyro were not used for flying the planes (only for autopilots or gun sight) and flying computer were not yet designed for planes... First were seen for V2 bombs and were not very effective.
So a complete and correct stability, added to a correct controllability was obtained only by design : correct airfoil and twist combination + sweep back.
The Northrop flying wings don't need computers or vertical surfaces until the props were changed for turbines... should have needed a little more sweep...