"The downward wing configuration makes the airframe slightly unstable, until now an undesirable quality in passenger flight but thanks to advances in computer t

"The downward wing configuration makes the airframe slightly unstable, until now an undesirable quality in passenger flight but thanks to advances in computer technology Stratoliner can provide a very stable platform whilst being exceptionally manoeuvrable for a jet of its size." Why is it not better to just not use this kind of design and not rely on the computer to make it work?