Northrop Grumman revealed a flying-wing tailsitter design as the company’s offering for an experimental unmanned air system that can bring Predator-sized payload and endurance to naval ships smaller than aircraft carriers.
The design concept forms the basis of Northrop’s proposal for the Defense Advanced Research Projects Agency’s Tern programme. DARPA plans to award the contract in January to build and fly a full-scale prototype from a barge or decommissioned navy ship, says Chris Hernandez, senior vice-president of research, technology and advanced design for Northrop.
At DARPA’s request, Northrop is not releasing pictures or drawings of its Tern concept, but displayed a model of the aircraft on a 11 December tour for journalists in Los Angeles.
Northrop’s unmanned Tern design harkens back to the manned Lockheed XFV-1 concept of the early 1950s, which also featured a tailsitter configuration with nose-mounted counter-rotating propellers to provide vertical thrust for take-off and landing and forward thrust in horizontal flight.
But Northrop adds to the tailsitter approach by combining the engine with a pure flying wing design, a hallmark of several of the company’s bomber and surveillance aircraft since the mid-1930s.
DARPA wants an unmanned vehicle that can operate from DDG-class ships or smaller, with the ability to carry a 272kg (600lb) payload up to 900nm (1,670km). It also must be able to land vertically on a rolling deck in Sea State 5 conditions, meaning waves between 2.5m to 4m tall.
Northrop’s last remaining competitor for the Tern contract until September was AeroVironment, which announced in September that it had not been down-selected for phase III. Although Northrop has no known rivals for the Tern award, company officials say DARPA has not awarded the contract yet.
Northrop’s tailsitter design includes a set of large counter-rotating propellers covering almost two-thirds of a roughly 9.14m (30ft)-diameter wingspan, Hernandez says. It carriers weapons and sensors as stores underneath the wing. Although the company seems confident about its performance calculations, it is waiting for wind tunnel test data next moth to validate the aerodynamic claims.
“Many people will hold their reservations until they see the wind tunnel data,” Hernandez says.