The world's biggest plane is a step closer to its
first flight, after passing another major milestone.
Named Stratolaunch, the colossal
aircraft travelled down the runway under its own power for the first
time, firing all six of its Pratt and Whitney turbofan engines - each
weighing 8,940lbs (4,000kg).
During the aircraft's first low-speed taxi test,
Stratolaunch successfully travelled down the runway at 25 knots (28mph/45km/h).
Once testing has been completed, the aircraft - which
has a wingspan longer than a football field - will be used to launch satellites
and other objects into space.
This could include a Dream Chaser spaceship, which
could act as a mini-shuttle to reach low Earth orbit destinations and return
astronauts or payloads to a runway within 24 hours.
It is expected to take the skies for the first time in
2019.
The main purpose of the test was to put the aircraft’s
ability to steer and stop through its paces.
A ground team from Stratolaunch Systems Corp monitored
a number of systems, including steering, braking, anti-skid and
telemetry.
All objectives of this test were achieved.
In a written statement George Bugg, aircraft
program manager at Stratolaunch, said: 'This was another exciting milestone for
our team and the program.
'Our crew was able to demonstrate ground directional
control with nose gear steering, and our brake systems were exercised successfully
on the runway.
'Our first low speed taxi test is a very important
step toward first flight. We are all proud and excited.'
Since the first engine runs in September, the
Stratolaunch team has performed a series of engine tests from a newly established
Stratolaunch Mission Control Center (MCC) located at its facility at the Mojave
Air and Space Port in California.
The MCC serves as the Seattle-based firm's hub for
testing communications and will eventually be the centre of its aircraft and
launch operations.
Once low-speed taxi tests have been safely completed,
the company will begin the next phase of taxi testing, which will include
increased speeds.
The plane is the vision of Microsoft co-founder Paul
Allen who wants it to act as a giant air pad in the sky, allowing payloads to
reach space faster and at a lower cost than existing technologies.
The aircraft is so huge if it sat in the centre
of a football field, it would be wide enough for its wings to reach 12.5 feet
(3.8 metres) beyond each goalpost.
Test flights were expected for 2016 and 2017, but
project delays have pushed back the date to sometime in 2019.
The Stratolaunch team completed fuel testing of all
six fuel tanks on September 19, to ensure their proper operations, at the
Mojave Air and Space Port.
Each of the six tanks were filled independently to
check their fuel mechanisms were working correctly and to that they were
properly sealed.
In addition to fuel testing, engineers began testing
the flight control system.
So far, they have have exercised the full limits of
motion and rate of deflection of the wings control surfaces and stabilisers.
Building up to this week’s engine tests, electrical,
pneumatic, and fire detection systems were also given a once over.
Writing on the Stratolaunch website, CEO Jean Floyd said: 'Engine testing was
conducted with a build-up approach and consisted of three phases.
'First as a "dry motor", where we used an
auxiliary power unit to charge the engine.
'Next, as a "wet motor" where we introduced
fuel. 'Finally, each engine was started one at a time and allowed to
idle.
'In these initial tests, each of the six engines
operated as expected.'
Over the next few months, they plan to continue to
test the aircraft’s engines at higher power levels and varying configurations,
culminating in the start of taxi tests on the runway.
Paul Allen unveiled the world's largest aircraft at
the start of June.
The massive plane rolled out by Allen's aerospace
firm, Stratolaunch Systems, features the longest wingspan of any aircraft ever
built, according to Popular Mechanics.
With a wingspan of 385 feet, the six-engine plane will
be larger than Howard Hughes' 1947 H-4 Hercules, known as the 'Spruce Goose,'
and the Antonov An-225, a Soviet-era cargo plane originally built to transport
the Buran space shuttle that is currently the world's largest aircraft.
The Stratolaunch is an aircraft that is designed to
carry rockets between its two fuselages.
In 2011, the project's cost was initially estimated to
be at $300million, though there is no word as to the updated figures.
After the plane reaches altitude, it would then drop
the launch vehicle, which will subsequently fire its boosters and launch into
space from the air.
Images of the mammoth plane, nicknamed the 'Roc,' were
released.
It shows the plane emerging from its hangar in California's Mojave Desert.
The plane was built by Scaled Composites, an aerospace
company founded by Allen's partner in the Stratolaunch project, Burt Rutan.
Scaled is owned by defense contractor Northrop
Grumman.
The Stratolaunch weighs approximately 500,000 pounds
without any cargo.
It is designed to carry a maximum takeoff weight of
1.3million pounds, according to The Verge.
The plane rolls around with the aid of 28 wheels. Once
airborne, it is powered by six 747 aircraft engines.
The size of the plane will enable it to serve as an
airborne rocket launcher.
Traditionally, satellites and other aircraft have been
launched into space from a launchpad. This requires a tremendous amount of
fuel.
The Stratolaunch, on the other hand, will enable
rockets to have a 'head start' since they will be carried into the sky before
they launch into space.
Last year, Stratolaunch signed a deal with aerospace
and defense firm Orbital ATK.
Under terms of the deal, the Stratolaunch will propel
Orbital's Pegasus XL rocket, which is used to send small satellites into space.
Allen's move coincides with a surge of new businesses
planning to sell internet access, Earth imagery, climate data and other
services from networks of hundreds of satellites in low-altitude orbits around
Earth.
But his vision is different from what Elon Musk's
SpaceX, Jeff Bezos' Blue Origin, Richard Branson's Virgin Galactic and other
companies have for building commercial highways to space.
Musk's goal is to fly people to Mars. Bezos is
developing low-cost, reusable rockets with the goal of moving energy-intensive,
heavy industry off Earth. Branson is focused on space tourism and a small
satellite launcher.
The advantage of Allen's approach will be the ability
to position the plane so satellites can be directly delivered into very precise
orbits and do so quickly, without launch range scheduling issues and
weather-related delays, Chuck Beames, who oversees Allen's space ventures,
said.
The Stratolaunch plane looks nothing like its behemoth
predecessor aircraft.
Rather than transporting heavy cargo inside a main
body section, Stratolaunch is a twin-fuselage craft that incorporates engines,
landing gear, avionics and other parts from a pair of Boeing 747 jets coupled
with a frame, wings and skin handmade of lightweight composites.
Designed and built by Northrop Grumman Corp's Scaled
Composites, the plane is similar in form and function to Scaled's aircraft
built to ferry spaceships into the air and release them for independent rocket
rides beyond the atmosphere, a service Richard Branson's Virgin Galactic
intends to offer to paying passengers.
Stratolaunch plans a similar service for satellites,
particularly the low-Earth orbiting multi-hundred member constellations under
development by companies including SpaceX and Google's Terra Bella to provide
internet access, Earth imagery and other data.
But Stratolaunch will offer quick and precise
satellite positioning, a service that will set it apart from competitors.
These satellite networks, based on low-cost
spacecraft, are the fastest-growing segment of the global satellite industry
which reported more than $208billion in revenue 2015, according to a Satellite
Industry Association report.
(Evangle Luo of
TTFLY shared with you)
