A rendering of a prototype of the Destinus L hypersonic jet. Destinus European startup Destinus is designing a series of ultra-speedy aircraft capable of reaching Mach 5. Liquid hydrogen combined with jet and rocket engines will allow the plane to cruise at 108,000 feet. Models "Destinus S" and "Destinus L" could connect cities like New York and London in just 90 minutes. The world has not seen a supersonic aircraft since the demise of the Concorde in 2003. The legendary plane connected New York and London in as little as three and a half hours, but several factors including its...