It doesn't have crazy swept wings and it doesn't fly at Mach 7, but this concept aircraft from Boeing is what we'll all probably be stuffed into by 2045. It runs on cryogenic liquified natural gas, and beats the fuel efficiency by the current generation of passenger jets by a whopping 60%.
NASA has been doing its best not to get swept away with crazy concepts, and the agency is busy commissioning studies from companies such as Boeing looking for realistic (and we should emphasize that: realistic) projections for the next few generations of passenger aircraft. NASA numbers these generations starting with "N+1," where "N" refers to aircraft like the 777 and "+1" is the generation following that, of which the Dreamliner is a start.
For generations N+3 and N+4 (between 2035 and 2045), Boeing put forward a concept called SUGAR Freeze, where "SUGAR" stands for Subsonic Ultra Green Aircraft Research, and Freeze is referring to the fuel: cryogenically stored liquified natural gas (LNG). It's reasonably tame looking, with the most distinguishing feature being low-drag, truss-braced wings, but the airframe itself is extremely lightweight and efficient.
The LNG propulsion system was chosen due to low fuel burn and low emissions, coupled with projected low price and high availability that seems likely to persist through at least 2035. LNG would be burned in unducted-fan hybrid engines, and these engines would be hooked up to a fuel cell that would in turn power a thruster mounted on the rear of the fuselage (pictured above: that ring at the tail), which would re-energize the wake of the aircraft to significantly reduce drag. Put all this stuff together, and you get an aircraft that's as much as 64% more efficient than a 737-800.
The reason that NASA is looking so far ahead is that it takes easily 20 years for even the least crazy technologies to make it through the research and development process into production aircraft, and NASA needs to know where to focus what is — at this stage — just basic research. But this stuff is realistic, and it's likely the direction for the future of commuter aircraft. This isn't to say that there won't be sleek scramjet-powered airplanes zipping around the world, but even by 2045, that overbooked flight from Newark to Atlanta is much more likely to be on something like SUGAR Freeze.
Incidentally, we'd like to nominate "SUGAR Freeze" for aircraft concept name of the year. Aaand we're going to get ourselves Icees now.
Via Aviation Week