When the Navy awarded Northrop Grumman the development contract for the X-47B in 2007, it had three main requirements: The aircraft must be carrier-suitable, it should be able to evade enemy radar, and it should be autonomous, not simply automated. The team already had a stealth frame designed, a blended-wing configuration known as a cranked kite. It lacked sharp surface features that might return strong radar signatures. As they adapted it, they kept it small, just 62.1 feet across, and with wings that folded up so the finished aircraft would store easily on a hangar deck. They also managed to build in a Pratt & Whitney F100 jet engine—the same one that powers some F-15 and F-16 fighter jets—making the aircraft faster and more powerful than the propeller-driven Reaper or Predator drones.
With the X-47B’s basic design in place, engineers began to develop the aircraft’s senses. They loaded it with GPS equipment, accelerometers, altimeters, gyroscopes and other classified hardware, all aimed at providing the flight-control computer with the information necessary to sustain autonomous flight. They also developed a high-speed data link capable of swapping digital information with a ground station or aircraft carrier across at least 50 nautical miles.
As one group of engineers worked on the hardware, another built a highly sophisticated autopilot system controlled by a layer of artificial intelligence. The software would translate the sensor data into decisions and commands for the flight computer. To train the X-47B, they ran its software though tens of thousands of virtual missions, pitting it against a range of simulated conditions and refining its code with every trial.
In July 2010 the team at Northrop’s manufacturing facility at Plant 42 in Palmdale, California, loaded the X-47B onto a trailer and towed it up the road to Edwards Air Force Base, where it would make its maiden flight the following February. Beneath a blanket of thin, high clouds, a mix of Northrop staff and Navy personnel watched as the craft screamed down the runway, lifted off and made a cautious 29-minute flight, circling the base at 5,000 feet while downlinking data to researchers on the ground. Engineers had planned to make 50 such flights to test the limits of the X-47B but it performed so well and so consistently, they stopped after just 16 trials. The next step was to get it ready for the carrier.single page
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.