The Stratolaunch plane has three engines on each wing. (Stratolaunch Photo / Dylan Schwartz)
The world’s biggest airplane hit another milestone this week with the completion of the first phase of engine testing at California’s Mojave Air and Space Port, according to Stratolaunch, the space venture backed by Microsoft co-founder Paul Allen.
Stratolaunch’s CEO, Jean Floyd, reported today that all six of the plane’s Pratt & Whitney turbofan engines were started up for the first time.
“Our aircraft is one step closer to providing convenient, reliable and routine access to low Earth orbit,” Floyd said in a news release.
Allen founded Stratolaunch in 2011 with the goal of creating an air-launch system that can drop rockets from an airplane in midflight and send payloads into virtually any orbital inclination. Because the system relies on an airplane rather than a fixed launch pad, Stratolaunch theoretically could make orbital deliveries without worrying so much about the weather.
But to create the launch platform, Stratolaunch and its Mojave-based construction contractor, Scaled Composites, have to build and test a twin-fuselage airplane with an unprecedented 385-foot wingspan.
The landing gear and engines have been taken from Boeing 747 jets and added to the carbon-composite airframe. The plane was rolled out for the first time this Mayand is going through months’ worth of on-the-ground testing.
Floyd said the engine tests were conducted in three steps, starting with a “dry motor” phase in which an auxiliary power unit was used to charge each engine. In the second phase, fuel was introduced into the system for a “wet motor.” The third phase involved starting up each engine, one at a time, and having it idle.
“In these initial tests, each of the engines operated as expected,” he said.
Floyd said all six of the plane’s fuel tanks were filled independently to ensure proper operation and validate the tanks’ seals.
The team has also begin testing the flight control system. “So far we have exercised the full limits of motion and rate of deflection of control surfaces on the wing and stabilizers,” Floyd wrote.
Over the next few months, the engines will be tested at higher power levels and varying configurations, leading up to the start of taxi tests, Floyd said.
Stratolaunch tests all six engines on its massive rocket-launching plane
Getting one step closer to actually flying
This week, private spaceflight company Stratolaunch tested out the turbofan engines on its behemoth aircraft for the first time — all six of them. The engines were filled with fuel and allowed to idle one at a time at the company’s facility at the Mojave Air and Space Port in California. All six worked as expected, according to Stratolaunch.
It’s another big step for the company, helmed by Microscoft co-founder Paul Allen, as it readies the massive plane for flight. Boasting two fuselages and a wingspan wider than a football field, it’s currently the world’s largest aircraft, weighing 500,000 pounds when empty and unfueled. However, the company claims it will have a maximum takeoff weight of 1.3 million pounds.
Ultimately, Stratolaunch hopes to use the plane as a launch platform. The aircraft is designed to carry rockets, which will sit attached underneath the wing connecting the two fuselages. Once the plane reaches a certain altitude, the rocket is meant to detach and ignite its engine, carrying its payload the rest of the way into space. Thanks to its massive size, the plane is capable of carrying payloads up to 550,000 pounds.
One of the six Pratt and Whitney turbofan engines Image: Stratolaunch
However, the company is going to start out small at first. Stratolaunch signed a deal last year to launch Orbital ATK’s Pegasus XL rocket from the plane. Designed to launch from the air, the Pegasus is a fairly small rocket, capable of launching satellites weighing up to 1,000 pounds. It’s also perfectly capable of launching from a much smaller plane than the Stratolaunch one.
Still, it’ll be a while before any rockets are taking off with Stratolaunch. The company just rolled the plane out of its hangar for the first time in May, and the company still has a lot of tests to do on the engines before any big moves can begin. “Over the next few months, we will continue to test the aircraft’s engines at higher power levels and varying configurations, culminating to the start of taxi tests,” the company said in a statement.
