The world’s biggest aircraft will have a simple job: take a two-stage rocket to 9 000 metres, drop it, and get the hell out of the way as it blasts into orbit. – By Michael Belfiore
STUART WITT guns the motor of the white SUV known as Mojave One and drives it up a dun-coloured mound of earth. From atop his wind-swept perch, the CEO of the Mojave Air and Space Port surveys a fleet of graders and other heavy equipment churning up 7,7 ha of dirt beneath a blue desert sky.
At the moment, it’s just a sprawling construction site, but within two years, work will be completed on a pair of hulking buildings. One will be a fabrication facility for the world’s biggest aircraft. The other will be the hangar that houses it. “You’re looking at something that’s going to be fundamentally breathtaking,” Witt says.
The official name of the mammoth aircraft is Model 351, but it already has a nickname: the Roc, after the mythological bird big enough to carry away elephants for dinner.
The record-breaking plane, which will have six engines and twin fuselages, is being built to carry a rocket to 9 000 metres. From there, the rocket will drop from the plane and blast into space. The first payloads will consist of satellites and other cargo, but the programme’s backers say the rocket will eventually carry passengers. The Roc will be a flying launchpad – government and private-sector customers welcome.
Incredibly, the project has been in development for more than eight years under total secrecy. Then, this past December, billionaire Paul Allen announced his Stratolaunch project to the world at a press conference in Seattle.
When the space shuttle fleet was retired in 2011, the United States lost its only way to get astronauts off the planet. Stratolaunch is the latest private-sector initiative to try to fill that void. “For the first time since John Glenn, America cannot fly its own astronauts into space,” Allen said in Seattle. “Stratolaunch will build an air-launch system to give us orbital access to space with greater safety, flexibility and cost effectiveness, both for cargo and manned missions.”
In the process, the Stratolaunch team hopes to build a new American spaceflight industry. But there are more than government contracts at stake: when the cost of launches decreases, more industry satellites, tourists and science projects will reach orbit. Space will truly be open to the public.
To reach that lofty goal, Allen has assembled a team of mavericks from the private space industry to make Model 351 into flight-ready hardware. Scaled Composites, a Mojave-based firm founded by designer (and POPULAR MECHANICS Breakthrough Award winner) Burt Rutan, will make the aircraft. Says Rutan, who sits on the Stratolaunch board of directors: “To allow public access to orbit, we need to increase safety by a factor of one hundred. I think airborne launch will be a significant part of the safety solution.”
The rocket will also be made to order. For that, Allen approached PayPal co-creator Elon Musk, who founded Space Exploration Technologies (SpaceX). Building a two-stage rocket that will be dropped from an aircraft is the kind of bold challenge that SpaceX was created to tackle, but hitting the specifications for mass, centre of gravity and other technical details will be tricky. “We’re in what I call the rocket-design box,” says Gwynne Shotwell, SpaceX’s president, “where we can be only so long and weigh only so much but still need to get a specific amount of payload to orbit. Piece of cake.”
FLIGHT OF THE ROC
In 2015, hangar doors wider than the length of a football field will slide open. The 544-ton Stratolaunch mother ship will lumber directly on to Mojave’s Runway 30, which extends 3 800 m through the desert scrub toward the windmills churning the air in the foothills of the Tehachapi Mountains. The Roc’s gleaming white, 117 m wings will cast long, slender shadows as the plane moves into the bright California sun.
When air traffic controllers clear the Roc for take-off, its crew will throttle up six Pratt & Whitney 4056 turbofan jet engines, each of which generates about 293 000 newtons of thrust. The high-pitched turbine whine of a four-engine 747 reaches 140 decibels during take-off. That’s 20 decibels above the pain threshold – and the Stratolaunch vehicle will have two additional engines.
The shriek of the Roc on take-off will echo a long distance – which is one good reason to base its development in the empty desert at Mojave. Accelerating down the runway will put some flexion into the wings, probably giving them a bit of a flapping quality as the plane takes off.
Mojave will host test flights. Paid space launches, scheduled to begin in 2020, will depart from Cape Canaveral, Florida. There, the aircraft will carry a 36 m rocket mounted to the bottom of the spar connecting the fuselages. The sight will be dramatic – an aircraft with a wingspan greater than the length of a football field, carrying a rocket with wisps of vapour escaping from its cryogenic liquid oxygen tanks.
Allen envisions the system one day delivering as many as six people per flight into space. The passengers will buckle into seats inside a capsule at the rocket’s tip. Assuming the capsule has windows, these paying customers will be treated to views of the receding Florida coastline and, after a steady climb, the curvature of Earth.
And then it gets exciting. Once at 9 000 m, the Roc’s crew will start a brief countdown and flip the sequence of switches that releases the rocket. The pilots will then veer away sharply to stay clear of the rocket’s flight path.
During the drop, fins will pitch the rocket at a steep angle for its impending climb to space. The capsule passengers’ orientation will shift: imagine tipping over your chair, and that brief but gut-wrenching free-fall. And then imagine being slammed back into your seat by g-forces as the rocket’s engines ignite, exerting over 2,2 million newtons of thrust.
Once in space, 90 000 m above the release point, the rocket will drop the first stage, and the second will fire, flinging the capsule (or 6 100 kg of payload) the rest of the way into orbit. By then, the passengers will be floating in their harnesses.
BLAST-OFFS FROM ALTITUDE
Launching spacecraft from aircraft is an idea that is as old as spaceflight. In the early 1960s, pilots – including future Apollo 11 astronaut Neil Armstrong – began shooting for the edge of space in X-15 rocket planes dropped from B-52 bombers. In the late 1990s, the Pentagon began investing in air-launch ventures to develop the capability of deploying a spy satellite over an unexpected hotspot or replacing a disabled sat.
Private space companies have launched small rockets from converted civilian airliners and the cargo bays of military transport aircraft (see “Why air launch?” elsewhere in this article). But the concept has never before been tried on the scale of the Roc.
Rutan and Allen’s earlier space collaboration now seems like a test run for Stratolaunch, both in terms of strategy and design. In 2004, a mother ship called WhiteKnight carried a manned spacecraft, SpaceShip-One, to launch altitude. From there, SpaceShipOne reached 99 900 m and then landed under its own power. When Scaled was able to repeat the feat within 14 days, the company won the $10 million Ansari X Prize. Like the Roc, WhiteKnight carried its payload between twin spars, but the Stratolaunch aircraft’s cockpit is nested at the tip of one spar.
Allen won’t confirm Stratolaunch’s price tag, but he says it “is going to end up costing at least an order of magnitude more than what I put into SpaceShipOne ($28 million)”. Allen and company believe that the hundreds of millions of dollars and the design challenges of the project will be offset by an “any orbit, any time” capability.
When launching a spacecraft to a target in orbit – say, a space hotel – a launch provider can either wait until the facility is overhead, or launch, enter orbit and spend days chasing the destination. But the Roc will be able to take off from any runway long enough to accommodate it, fly 2 400 km, and launch a rocket when the orbital facility is overhead.
The Stratolaunch team isn’t speculating as to who or what will eventually hire the system to fl y to space. “Paul has tasked us with getting the design moving forward,” says Stratolaunch president and former Nasa chief engineer Gary Wentz. “Right now, we’re not pursuing customers.”
In early February, a pair of United Airlines 747s from Victorville, California, landed at Mojave. They won’t leave intact. The two aircraft will be cut to pieces and their parts repurposed for the Stratolaunch prototype, including the six engines that will be mounted on the Roc’s wings. Engineers will also cannibalise the airliners’ landing gear.
The Roc’s airframe will be new, built of carbon fibre. Aerospace engineers are finalising that design in Scaled’s engineering offices in Hangar 78 at Mojave. Says Kevin Mickey, Scaled’s executive vicepresident: “We’ve grown up with airplanes that are of a scale where you call 10 of your buddies over and say, ‘I’m going to put this wing on today’. Building an airplane of this size is more of a shipyardtype logistic challenge.” So cranes and big jigs will be the order of the day.
The Roc is not regarded as pretty, even by its creators. “We’re all aircraft guys; we love swoopy shapes,” Scaled programme manager Joseph Ruddy says. “But that’s not this thing’s job. This thing’s job is to carry this rocket and drop it.”
Engineer and test pilot Doug Shane, Rutan’s successor as head of Scaled, says the team will fabricate as many identical carbon fibre-skin sections as possible. “If you look at our products, it’s very unusual to have any common geometry to any adjacent part of the vehicle,” Shane says. With flat sides on the fuselage, Scaled can make panels and clone the part for use almost anywhere on the aircraft.
Given Rutan’s penchant for aviation firsts – aircraft based on his designs have set multiple round-the-world records – one might suspect he joined the Stratolaunch project partly because it gives him a shot at one last career-capping superlative. But Rutan strongly disagrees with that view. “It would be nice to not have to build the world’s largest airplane to do the Stratolaunch mission.”
No one at Mojave is currently building rockets at the Stratolaunch scale, so Allen turned to Elon Musk. His SpaceX skunkworks is brazenly rewriting the rules of spaceflight by creating and launching rockets quickly and cheaply.
The company has already flown the Falcon 9 rocket, named for its nine main engines, and the Dragon space capsule into orbit. The company is now preparing for cargo flights to the International Space Station. Musk says manned flights could commence as early as 2014.
The Stratolaunch rocket will have the same diameter as the Falcon 9 (3,65 m), but engineers will trim its length by about 18 metres. “We call it the Falcon 9 Shorty,” SpaceX president Shotwell says. Engineers will stunt the rocket by taking out some of the barrel sections that they weld together to make up a typical Falcon 9.
Many elements of the design are not yet finalised. Even the number of rocket engines has not been settled: Shotwell wants to stick with nine engines; Wentz wants fewer. “Nine engines are not required for the performance or control of this rocket,” he says. “Including them would add cost and mass.”
They have to come to an agreement quickly, as the project is on a tight schedule. Wentz’s timetable calls for Roc flight tests to start in 2015; flights with an actual rocket won’t begin until 2020 in Florida.
Scaled must lure engineering and design talent to Mojave to staff up Stratolaunch. “The biggest challenge is finding the people who have the right mindset to do this kind of work, who want to take responsibility for the parts they do (create),” Ruddy says. “We have to adjust them to our culture. A lot of aerospace is geared to production-type mentality. The prototype world is a little different.”
Stratolaunch suits Witt’s vision of Mojave as the centre of this prototype world, where cutting-edge aerospace companies have the room to innovate. “What brought the Wright brothers to Kitty Hawk was freedom from encroachment of the press, freedom from industrial espionage, and a steady breeze,” Witt says. “The fact that we were able to keep this under wraps for nearly nine years says that we still enjoy the elements that took Orville and Wilbur to Kitty Hawk.”
No one will mistake the 544 310 kg Roc for the 274 kg 1903 Wright Flyer. But if this astounding piece of engineering takes to the sky, engines screaming and rocket blazing, the aerospace pantheon will welcome a new aircraft – a very big one.
STRATOLAUNCH WINGSPAN: 117 M
LENGTH: 65,5 M
HUGHES H-4 HERCULES (SPRUCE GOOSE)
WINGSPAN: 97,5 M
LENGTH: 66,7 M
WINGSPAN: 79,5 M
LENGTH: 73,1 M
WINGSPAN: 23,8 M
LENGTH: 56 M
MERLIN ENGINES, 556 000 NEWTONS OF THRUST EACH AT SEA LEVEL
TWO-STAGE ROCKET, 36,5 M LONG
6 100 KG OF CARGO TO LOWEARTH ORBIT
SIX PW4056 TURBOFAN ENGINES FROM TWO BOEING 747-400S
1) MOTHER SHIP FLIES TO LAUNCH POINT AT 9 000 M.
2) ROCKET BOOSTER’S FINS ORIENT ROCKET VERTICALLY AS IT DROPS.
3) ROCKET ENGINES IGNITE, SENDING PAYLOAD TO ORBIT.
Air-to-space dream team
There are plenty of ambitious private space companies, but the reputations of the
three partners behind Stratolaunch Systems raise expectations sky-high. Each has
made a career by defying the status quo.
‘Why build a new airplane to ferry rockets?’ ‘Specialised aircraft for space launch are optimized for their payloads,’ Burt Rutan says. ‘Joining two 747s would not get you an airplane capable of launching the Stratolaunch booster.’
Burt Rutan, founder, Scaled Composites
This forceful, iconoclastic and brilliant engineer is best known for designing SpaceShipOne, the first privately built craft to carry people into space. Rutan, now retired, sits on Stratolaunch’s board of directors; Scaled is building the aircraft.
Elon Musk, co-founder of PayPal, Tesla Motors, and Space Exploration Technologies (SpaceX) Musk’s rocketeers are trying to make SpaceX the first private company to resupply the International Space Station – and create a launcher that costs one-quarter the price of comparable rockets.
Paul Allen, co-founder, Microsoft
This billionaire was the sole founder of Rutan’s SpaceShipOne project. Stratolaunch, which will be the first wholly privately funded space transport system, is his second space venture. “It will keep America at the forefront of space exploration,” he says.
Stuart Witt, CEO, Mojave Air and Space Port
Witt has been privy to the Stratolaunch plan for years, and prepared his facility for its commencement. He extended runways and oriented the Stratolaunch’s hangar doors so they will open directly on to a runway he extended in 2007.
Private space planes
The huge plane in the Stratolaunch system is used to hoist a rocket to high altitude, release it, then veer away as the rocket launches into space. But the mother ship itself is not a space
plane. That designation is reserved for aircraft that can reach space under their own power,
manoeuvre there, return to Earth, and land. Private space companies are busy designing these
reusable craft. Here are three new models.
LYNX / 9 m long
This suborbital-only space plane from XCOR, based at California’s Mojave Air and Space Port, is designed to fly microgravity research payloads, as well as tourists, just past the edge of space. Taxi tests are scheduled for late 2012; a short first flight could come by year’s end.
DREAM CHASER / 9 m long
This seven-passenger space plane, developed by Sierra Nevada Corporation, will launch from Cape Canaveral atop an Atlas V rocket, enter orbit, return to the atmosphere, and land on a conventional runway. NASA-funded testing means first flights as early as mid-year. Sierra Nevada says regular flights will start in 2016.
SKYLON / 82 m long
This single-stage unpiloted craft, made by England’s Reaction Engines, will blast directly into space from a runway without a boost from an airplane or rocket, carrying cargo or a passenger compartment. Engine tests began last year; company engineers expect flights within a decade.
Why air launch?
Launching spacecraft from aircraft is not a new concept – and it has advantages over a ground launch. An air-launched rocket is lighter because it needs less fuel to reach orbit and doesn’t require shielding to protect it from the engines’ acoustic energy, which reflects off the ground.
1963: NASA pilot Joseph Walker reaches space three times in an X-15 rocket plane dropped from a B-52. He is the first person to get to space more than once.
1990: Orbital Sciences becomes the first private space launch company when it drops a Pegasus rocket from a B-52. The system, using a Lockheed L-1011, is still in operation.
2004: Scaled Composites’ WhiteKnight takes off from California’s Mojave Air and Space Port and launches SpaceShipOne from its position beneath the plane’s central fuselage. A larger version, WhiteKnightTwo, is undergoing flight tests.
2006: AirLaunch, a Seattle-area company working under a Pentagon contract, drops a space rocket from the back door of a C-17, setting a record for the heaviest single object dropped from the military cargo plane – 29 000 kilograms. In 2008, when the contract ends, the company folds.
2010: Google Lunar X Prize competitor ARCA, based in Romania, announces plans to launch a three-stage space rocket from a balloon. In October 2010, ARCA fires a prototype rocket from a balloon at 13 700 metres.
Video: Visit Paul Allen’s Stratolaunch project to revolutionise space transportation to watch a video revealing more about the Stratolaunch project.