Scramjets are Go - Hypersonics are Back
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'Microsoft is the team leader...'
The scramjet technology has its doubters but as far as they are concerned, if scramjet did not have a long-term commercial application then why is NASA building one?
The technology is not new; it has been around for something like 40 years. It was inevitable that one day, a prototype would be built and the story of flight would move forward.
The X-40, the predecessor of the X-43A
So, what is a scramjet?
Basically, it is a very simple concept with roots in the ramjet engines that powered Germany's infamous V1 "Buzz Bombs". This basic design called for the opening and closing in cycle of shutters on the intake side of the engine. When the shutters opened, 400 mph air was forced in, shutters closed, air was mixed with fuel, combusted, then exhausted as thrust. The rapid opening and closing of the shutters produced the buzz effect heard in the target area. When these cruise missile predecessors reached the target vicinity, a simple but effective targeting mechanism shut down the engine and the V1 began its deadly descent -- exploding on impact.
Because of their relative slowness (400 mph+) the RAF found that it was possible for Hawker Typhoon and Tempest fighter craft, equipped with the powerful 24-cylinder Napier-Sabre engine, to overtake the V1, slip a wing under the diminutive lift appendages of the missile and bank away. The result was a destabilising of the V1's delicate gyroscopic guidance system, thus causing it to crash.
Considerably much more efficient and powerful than this war time relative, current scramjet engines are fuelled by hydrogen and take their required oxygen from the atmosphere at supersonic speed. However, in order to get to supersonic speed in the first place the NASA aircraft will require a rocket boost.
It is highly possible that the X-43A could reach speeds of Mach 10 eventually, which is over 7,000 mph (11,500 kph).
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