One thing has always been true about rockets: The farther and faster
you want to go, the bigger your rocket needs to be.
Why? Rockets combine a liquid fuel with liquid oxygen to create thrust. Take
away the need for liquid oxygen and your spacecraft can be smaller or carry
more payload.
That's the idea behind a different propulsion system called "scramjet," or
Supersonic Combustion Ramjet: The oxygen needed by the engine to combust is
taken from the atmosphere passing through the vehicle, instead of from a
tank onboard. The craft becomes smaller, lighter and faster.
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How fast? Researchers predict scramjet speeds could reach 15
times the speed of sound. An 18-hour trip to Tokyo from New York City
becomes a 2-hour flight.
A look at one of NASA's developmental
scramjets, the X-43A, undergoing ground testing.
On August 16, 2002, the University of Queensland in Australia completed the
first successful flight of a scramjet vehicle, reaching speeds of Mach 7, or
seven times the speed of sound.
NASA's Hyper-X program is working to develop scramjets into a practical
technology. The X-43A, a 12-foot long
scramjet-powered research vehicle, was constructed by MicroCraft, Inc., now
known as Alliant Techsystems, Inc. The company fabricated three X-43A
aircraft for NASA, to be flown aboard modified Pegasus rockets developed by
the Orbital Sciences Corporation. The Pegasus is dropped by a B-52 aircraft
and launched to an altitude of over 90,000 feet, where the X-43A is released
and flown under its own power.
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Each of the three vehicles appear identical but have slightly
different oxygen intake designs, based on what speed their test flights are
planned to accomplish. The first test flight of the X-43A, which took place
on June 2, 2001, failed due to a stabilization problem with the booster
rocket's directional fins.
An artist's conception of the X-43A in flight.
The vehicle will be tested at speeds up to Mach 10.
The Hyper-X program is a joint project between the Langley Research Center
in Hampton, Va. and Dryden Flight Research Center in Edwards, Calif. The
next developmental flight of this system is scheduled for no earlier than
February 21, 2004.
NASA's John F. Kennedy Space Center, Dryden Flight Research
Center, and Langley Research Center.
Scramjet engines would be capable of flying from New York to Tokyo
in two hours. They’ve been in development for decades and governments
from around the world - USA, Australia and China - are finally making
them a reality.So just how fast is a scramjet? You may need
a bit of comparison:
- A Boeing 747 cruises at 567 mph (Mach 0.85).
- The Concorde was capable of speeds of up to 1,330 mph
(Mach 2.02).
- An F-14 Tomcat maxes out at 1,544 mph (Mach 2.34).
- The SR-71 Blackbird holds the speed record: 2,511 mph
(Mach 3.3).
- Scramjets are projected at Mach 15, that’s
upwards of 10,000 mph.
The jet engines of today aren’t able to go faster than Mach 3
because they use turbines that would melt under the outrageous
temperatures that occur beyond that speed. So how is it possible to
weather the storm? Take out the turbines. Scramjets are force-fed air
engines with no moving or melt able components.
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Inaugural attempts at this technology began with Reagan
announcing a public scramjet project called the
National Aerospace Plane (Rockwell X-30) in 1986. Dreams of “a new
Orient Express” scheduled to have the technology up and running to
ferry passengers by the 90’s. President Clinton canceled the project
in 1994 because of all of the barriers and problems the research had.
Yet, as usual, the lessons of yesteryear gave us insight for
today's research. Instead of trying to create a plane that can takeoff
and reach Mach 25 within moments researchers are slowly developing the
engines to instead go off in stages.
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The first field tested scramjet flight was in 2002 by Australian
researchers, called HyShot. It was essentially a rocket with a
scramjet engine strapped on it that was launched 20 miles above the
surface of the earth. Upon it’s re-entry the engine fired for five
seconds, reaching 5,000 miles per hour (Mach 7.6) before crashing into
the ground.
In 2004 NASA’s
X-43A, a rocket craft, was launched off a moving airplane and
reached a jaw dropping 7,307 mph (Mach 9.6) after 10 seconds. The new
goal is 100 seconds of continuous flight. The X-1 engine design is
currently being tested in Langley and hopefuls think that its flight
time is capable of being extended to an hour of continuous flight.
So when will you finally be able to enjoy the benefits of all
this blazing, neck-whipping speed? Darpa’s HTV-3X Blackswift is an
unmanned vehicle that is set to make it’s first flight in 2012. After
that it’s all a matter of adding some seats and charging a hell of a
premium.
The Falcon program objectives are to develop and demonstrate hypersonic technologies that will enable prompt global reach missions. This capability is envisioned to entail a reusable Hypersonic Cruise Vehicle (HCV) capable of delivering 12,000 pounds of payload at a distance of 9,000 nautical miles from CONUS in less than two hours. The technologies required by a HCV include high lift-to-drag technologies, high temperature materials, thermal protection systems, and guidance, navigation, and control. Leveraging technology developed under the Hypersonic Flight (HyFly) program, Falcon will address the implications of hypersonic flight and reusability using a series of hypersonic technology vehicles (HTVs) to incrementally demonstrate these required technologies in flight. In order to implement this flight test program in an affordable manner, Falcon will develop a low cost, responsive Small Launch Vehicle (SLV) that can be launched for $5M or less. In addition to HTV sub-orbital launches, the SLV will be capable of launching small satellites into low earth and sun-synchronous orbits and will provide the nation a new, small payload access to space capability. Thus, the Falcon program addresses many high priority mission areas and applications such as global presence and space lift. DARPA established an MOA with the Air Force for this program in May 2003 and with NASA in October 2004. Falcon capabilities are planned for transition to the Air Force.
