British aerospace company, Reaction Engines has been 10 years in the making to create the most advanced jet aircraft in the world.
The SABRE will have the ability to travel at speeds in excess of over Mach 5.
They are doing this by super cooling the air intake by using liquid hydrogen.
“These engines are a step change in propulsion technology,” said managing director and chief engineer Alan Bond, in an interview with The Star. “So at a stroke, they make Mach 5 transport anywhere on the earth, for example, a possibility.”
“When you’re flying at Mach 5, the air’s going to get very hot…it’s going up to 1000 degrees centigrade,” explained Bond, who is a rocket scientist. “Before you can put that into an engine you have to cool it. Liquid hydrogen is an extremely good coolant, so we use that in a complex way to cool the air, then compress it to put it into the engines.”
“This is the only engine that we know of which is capable of realizing an aeroplane which can take off, fly into space, do a job, and come back and land. Then, a couple of days later do it all over again to a different orbit or whatever,” says Bond. “So that’s the excitement of it.”
It appears that the first engines off the blocks will be rocket engines to help add satellites into space.[SOURCE](http://www.thestar.com/news/the_world_daily/2014/08/uk_project_brings_us_a_step_closer_to_ultra_high_speed_air_travel___along_with_simpler_satellite_deployment.html)