A note to those readers of the Aug. 13 issue of Aviation Week & Space Technology who might think the picture on page 28, of two Global Hawks formating for aerial refueling, is wrongly captioned. Is it not - that IS how they will do it.
Photos: Northrop Grumman
In the reverse of normal probe-and-drogue refueling, the tanker (on the left, above) is fitted with a refueling probe on the nose and the receiver (right) is equipped with a hose-drum unit under the fuselage. The receiver trails the hose, the tanker comes up behind and plugs into the drogue, then pushes fuel uphill to the receiving aircraft.
This unusual arrangement was selected for DARPA's automomous high-altitude refueling, or KQ-X, demonstration because it minimizes the number of aircraft in the fleet that would need to be equipped as tankers, Northrop says.
The KQ-X demo uses two RQ-4A Global Hawks owned by NASA and to which Northrop shares access under a cooperative agreement. The unmanned aircraft are pictured flying in close formation during pre-contact testing in preparation for actual refueling hookups.
NASA needed the Global Hawks back to modify them ready for hurricane investigation flights from Wallops Island, Virginia, this summer. The aircraft will be available for Northrop to modify back to KQ-X configuration after those flights end in October. A schedule for the wet hook-up and fuel-transfer demo has yet to be agreed with DARPA, Northrop says.
Autonomous aerial refueling at high altitude is expected to extend the Global Hawk's flight time from 30-35hr to 120-125hr, an endurance set by payload reliability rather than any air-vehicle limit such as engine oil consumption.