Farnborough Air Show

Airbus Expands And Refines Air-to-Air Refueling

 - July 8, 2016, 4:00 AM
The A400M can now refuel fighters and transports from underwing pods, but helicopter stability in trail has proved problematic. A longer hose may be the solution.

Building on the hard-won experience of developing the A330MRTT (Multi-Role Tanker Transport), Airbus Defence & Space is exploring automatic air-to-air refueling (AAR), and developing a refueling kit for the C295 airlifter. The company is also trying to make good on a promise to have helicopters refuel from the A400M airlifter.

Manual AAR is very complex, according to Airbus D&S head of engineering Miguel Angel Morell. The company has developed image-processing software that automatically steers the refueling boom toward the receiver aircraft’s receptacle. This could reduce risk and save time in operations, it says. The boom operator would still manage the initial extension of the boom and its disconnection and retraction.

The software has been successfully trialed in the company’s A330MRTT engineering simulator, and in flight—although not yet as far as making contact. Those ultimate flight trials will follow at the end of the year. According to Morell, the Royal Australian Air Force—launch customer for the A330MRTT—is very interested. Meanwhile, Airbus D&S has developed new hose and drogue visual aids for receiver pilots, for bad weather and night operations, and to provide system status.

Boom operators are also being offered a new on-the-job inflight training opportunity. A “synthetic” receiver aircraft could be displayed on their monitoring screens, integrated with real images of the boom and environment. This “augmented reality” system has been trialed on the company’s A310 AAR testbed.

A prototype hose-and-drum mounted on a pallet has been fitted to the C295. The hose feeds through a tunnel that is fitted to the airlifter’s ramp. It has been deployed inflight and found to be stable between 95 and 140 knots indicated airspeed (IAS). An Airbus Helicopters H225 Caracal heavy helicopter has been flown behind the C295 to check for airflow issues. These have bedeviled the A400M helicopter AAR program, but there have been “no issues” with the C295, according to Morell. Dry contact flight trials are scheduled at the end of the year, after a fully-instrumented helicopter joins the program.

Turboprop aircraft and UAVs could also be refueled from the C295. Up to seven metric tons of fuel can be dispensed; from the C295’s internal fuel tanks, and also from an auxiliary fuel tank fitted in the fuselage.

The A400M is now cleared to refuel fighters and transports from underwing pods. The helicopter problem could be solved by using a longer hose: 120-feet instead of 80-feet. But the diameter of the hose must be reduced if it is to fit within the existing Cobham Mk908E pod, and it may have to be stiffened to prevent oscillation. Aerodynamic data has been obtained from wind tunnel tests at French research agency Onera and is now being analyzed. Airbus D&S hopes to proceed to flight tests before the end of the year. But the French air force couldn’t wait. It ordered two Lockheed Martin KC-130Js (and two C-130Js) last November.

However, the French air force is a new customer for the A330MRTT, one of seven that have given Airbus D&S 85 percent of the market, according to Jeronimo Amador, the company’s head of marketing for derivatives. He said that the 96 percent availability demonstrated by the 27 aircraft in service is the highest of any military aircraft. The company is exploring a range of additional connectivity options for the aircraft, including Link 16 data relay via Satcom or UHF radio, and an airborne laser terminal for wideband data relay, such as video. The A330 airliner is now available with an increased mtow (max takeoff weight) of 238 metric tons, and this could increase the tanker conversion’s payload/range by 20 percent, Amador said.

Airbus D&S has just bought an A330MRTT full flight simulator from Indra. It will be installed at the company’s Seville training center by mid-2018 so new pilots can qualify with zero flight time in the real aircraft. It will also offer training in hose-and-drogue refueling operations, and may be linked to a part-task trainer that conducts boom refueling training.