Hi! I'm building an 8' span B-2 Bomber and in the process I learned a few things. #1 Mach tuck - on aircraft with swept wings the center of lift shifts back as speed increases. it goes so far behind the c/g that swept wing airplanes become unstable at high speed and dive gaining speed and are unable to pull out. Airliners use a Mach Tuck computer that trims the stabilizer or pumps fuel to a tank in the vertical stab to counteract Mach Tuck. Another answer is also handy on any aircraft - build the wing with enough washout especially toward the wing tip to counter act this problem. #2 Dutch Roll - another problem with swept wing A/C is if it gets going sideways one wing is getting more air over it than the other so it gets more lift and drag. The extra lift and drag pulls the original wing back so far that the opposite wing is facing to far forward so it has to much lift and drag. It goes back and forth and gets worse unless corrected. Airliners use a Dutch Roll computer I'm using a rudder Gyro to stabilize my B-2. I hope this info is helpful. It sounds like allot of info but if you get an understanding for these principals then flying wings make more sense.