It is
time to take notice that the evolution of the scram-jet engine is
well underway and will surely yield an air breathing hydrocarbon
solution for ground to space lift capacity. I personally think that
larger will turn out to be easier to achieve.
A
system may still need a subsonic piggy back lift to launch altitude,
but that is well understood and pretty easy to engineer in, or at
least it has been solved for a long time.
We
can expect a scram-jet to pretty well stand on its tail and
accelerate into space while chasing a diminishing air supply.
Provided escape velocity is achieved, it can then coast into orbit.
Even better, it can use engine drag to slow down and ultimately fly
down to a landing.
At
least we are now seeing a serious effort to progress this technology.
HIFiRE
Scramjet Research Flight Will Advance Hypersonic Technology
ScienceDaily (May 12,
2012) — A team that includes NASA and the U.S. Air Force
Research Laboratory (AFRL) is celebrating the successful launch of an
experimental hypersonic scramjet research flight from the Pacific
Missile Range Facility on the island of Kauai, Hawaii.
NASA, AFRL and
Australia's Defence Science and Technology Organisation (DSTO) are
working with a number of partners on the HIFiRE (Hypersonic
International Flight Research Experimentation Program) program to
advance hypersonic flight -- normally defined as beginning at Mach 5
-- five times the speed of sound. The research program is aimed at
exploring the fundamental technologies needed to achieve practical
hypersonic flight. Being able to fly at hypersonic speeds could
revolutionize high speed, long distance flight and provide more
cost-effective access to space.
During the experiment
the scramjet -- aboard its sounding rocket -- climbed to about
100,000 feet (30,480 meters) in altitude, accelerated from Mach 6 to
Mach 8 (4,567 to 6,090 miles per hour; 7,350 to 9,800 kilometers per
hour) and operated about 12 seconds -- a big accomplishment for
flight at hypersonic speeds. It was the fourth of a planned series of
up to 10 flights under HIFiRE and the second focused on scramjet
engine research.
The HIFiRE 2 scramjet
research payload included a hypersonic inward turning inlet, followed
by a scramjet combustor and dual-exhaust nozzle. More than 700
instruments on board recorded and transmitted data to researchers on
the ground. The payload was developed under a partnership between the
AFRL and NASA, with contributions from the Navy's detachment at White
Sands Missile Range, N.M. and ATK GASL located in Ronkonkoma, N.Y.
"This is the
first time we have flight tested a hydrocarbon-fueled scramjet
accelerating from Mach 6 to Mach 8," said NASA Hypersonics
Project Scientist Ken Rock, based at NASA'S Langley Research Center
in Hampton, Va. "At Mach 6 the inlet compression and combustion
process was designed to reduce the flow to below Mach 1 -- subsonic
combustion. But at Mach 8 flight the flow remained greater than Mach
1 or supersonic throughout the engine. So this test will give us
unique scientific data about scramjets transitioning from subsonic to
supersonic combustion -- something we can't simulate in wind
tunnels."
The data collected
during the execution of the HIFiRE experiments is expected to make a
significant contribution to the development of future high-speed
air-breathing engine concepts and help improve design, modeling, and
simulation tools.
The success of the
three-stage launch system, consisting of two Terrier boost motors and
an Oriole sustainer motor, is another important achievement of the
HIFiRE 2 mission. The HIFiRE 2 mission, the first flight of this
sounding rocket configuration, opens the door for a new
high--performance flight configuration to support future Air Force,
Navy, and NASA flight research.
The HIFiRE team has
already achieved other milestones such as the design, assembly and
extensive pre-flight testing of the hypersonic vehicles and the
design of complex avionics and flight systems. Demonstrating
supersonic combustion in flight with a hydrocarbon fueled scramjet,
compared to a hydrogen-fueled scramjet, is significant, according to
researchers. While hydrogen fuel is more reactive, hydrocarbon fuel
offers many benefits, including operational simplicity and higher
fuel density so a hypersonic vehicle can carry more fuel. This
represents yet another noteworthy achievement for the HIFiRE program,
with additional test flights scheduled in the coming months and
years.
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