July 15, 2013
Credit: U.S. Navy
There is no doubt that the first-ever arrested landing of an unmanned aircraft on a carrier deck, a feat achieved last week by the U.S. Navy, will be among the most notable events in aerospace history.
But the dazzling display 70 mi. off the U.S. East Coast was followed by challenges, underscoring the complexity of achieving the Navy's longtime goal of marrying the power projection of its aircraft carrier fleet with the endurance and range of unmanned aircraft. Anomalies with the Unmanned Combat Air System's (UCAS) ship controls and navigation computer—experienced after the seminal landing—point to areas that will need work as the Navy eyes a carrier UAV purchase as soon as next year.
The Navy's second Northrop Grumman X-47B demonstrator, Salty Dog 502, made aviation history July 10 with the landing, which Navy Secretary Ray Mabus said helps to “make sure that we keep the technological edge” as countries such as China work to build stealthy aircraft and unmanned vehicles.
Though it is an achievement, the event underscores that the $1.4 billion program is experimental, as operators experienced an anomalous shift of the aircraft's controls after the landing. A third arrested-landing attempt was aborted, prompting the vehicle to divert to the backup landing site at Wallops Island Air Field, Va.
The first landing snagged the No. 3 wire as planned just after midday. The second followed a catapult takeoff from the deck and touched down with the No. 2, nine vertical inches (translating to a few horizontal feet) from the projected impact point, says Capt. Jaime Engdahl, Navy UCAS program manager.
Prior to the first landing, the on-deck landing systems officer (LSO) ordered a go-around, an intentional use of a standard procedure, to ensure the algorithms responded as needed. The LSO uses a digital interface to relay commands to the UCAS, and its software translates them.
Once the media and senior-level onlookers departed, a third landing attempt failed. The X-47B conducted an autonomous wave-off about 4 mi. from the carrier after it detected an anomaly during a routine check of the three onboard navigation computers. The aircraft then rejoined the pattern until a ship-based operator commanded a diversion to Wallops.