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Stratolaunch completes first phase of engine testing
Stratolaunch. © Stratolaunch Systems Corp.

Stratolaunch completes first phase of engine testing

The giant Stratolaunch aircraft, which is designed to carry the Orbital ATK Pegasus launch vehicle, has completed the first phase of engine testing, starting its six Pratt & Whitney turbofans for the first time.

Slightly less than four months after its roll-out on 31st May, the giant Stratolaunch aircraft has completed the first phase of engine testing, starting its six Pratt & Whitney PW4056 turbofans for the first time. The aircraft — which weighs in at 227,000kg and is the world’s largest aircraft by wingspan (117m) — is designed to carry the Orbital ATK Pegasus launch vehicle, thus providing a platform for the launch of small satellites (less than 1,000lb) into low Earth orbit.

Engine testing was conducted in three phases: first ‘dry,’ using an auxiliary power unit to charge the engine, then ‘wet,’ with fuel. Finally, each engine was started one at a time and allowed to idle. In these initial tests, each of the six engines is reported to have operated as expected.

Since roll-out, all six fuel tanks have been tested to ensure proper operations. Each of the six fuel tanks was filled independently to ensure proper operation of fuel mechanisms and to validate the tanks were properly sealed.

Flight control system tests have also begun. These have included examining the full limits of motion and rate of deflection of control surfaces on the wing and stabilizers. Electrical, pneumatic, and fire detection system tests were also successfully completed prior to engine testing.

Engine tests are scheduled to continue over the coming months at higher power levels and in varying configurations, culminating in taxi tests.

The aircraft is being built by Stratolaunch Systems Corp. in partnership with Scaled Composites. Both Orbital ATK and Scaled Composites are now units of Northrop Grumman.

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