The time when it will take less than an afternoon to fly completely around the world isn't too far off. Hypersonic jets, planes that go faster than the speed of sound, may be getting an upgrade that makes them much lighter and more fuel efficient. Check it:
But the large surface areas created by rectangular designs generate tremendous heat transfer into a vehicle, requiring extra fuel loads just to cool areas around the engine chamber. "Not only are the large surface areas inefficient, but the extra fuel also adds significant volume and weight to the aircraft," said Kothari, who holds a patent on an inward-turning vehicle design. "Single-stage-to-orbit travel utilizing a rectangular-shaped engine design would be difficult."
Kothari's engine is shaped like a funnel, where air comes in through a circular opening, increases in pressure as it passes through, then leaves with more thrust and less heating than through a rectangular design. The challenge is injecting fuel into the fast-moving air efficiently as it travels through the engine.
Is this actually going to happen, and if so will it happen in our lifetimes? Beats me, but hot damn, flying around the world in 4 hours would be pretty badass.