It's time to redefine the definition of fast. A Boeing 747? Too slow. The SR-71 Blackbird? Yawn. A scramjet hurtling at Mach 10, or 11,000 km/h (6,800 mph)? Now that's cooking with supersonically compressed gas.
Australian researchers successfully tested their HyCAUSE scramjet today, confirming that it had reached a speed of Mach 10, or 10 times the speed of sound.
First, a brief explainer. When rockets blast off, they need to carry not only fuel, but an oxidizer to ignite the fuel. In the case of the space shuttle, for example, both liquid hydrogen and oxygen are carried inside the orange external fuel tank.
In the case of a scramjet, you only carry the fuel part and then bring in oxygen from the atmosphere to combust the fuel. That's a lot of weight that you don't need to bring along.
It's complicated, though, because you need to get the oxygen compressed to a certain amount before it can be mixed in with the fuel for proper combustion. This is only possible at tremendous velocities - multiple times the speed of sound - where the pressure of the air will give the compression you need. In theory, scramjets could operate all the way up to Mach 24, which is all a vehicle needs to get into orbit.
And this is the kind of vehicle the Australians tested today.
HyCAUSE stands for the Hypersonic Collaborative Australia/United States
Experiment, and it's a collaboration between the Australian Defence
Science and Technology Organisation (DSTO) and the US Defense Advanced
Research Projects Agency.
The scramjet itself was carried aloft atop a TALOS rocket to an altitude of 530 km (330 miles). The scramjet kicked in, and it reached a top speed of Mach 10 during re-entry.
In the future, scramjets could bring down flight times, with travelers going from London to Sydney in a couple of hours. They could also be used for satellite launches, and highspeed delivery.
Of course, with the US military involved, there are other applications (but that's classified, so just use your imagination).
