A Sample Feature From Aviation News

Boeing’s 767 Tanker

Recent conflicts have reinforced the importance of air-to-air refuelling tankers. Assistant Editor Dino Carrara reviews the 767 Tanker Transport programme, launched by Boeing to offer an all-new refueller and capitalise on a growing need to replace older tankers.

Above: A promotional doctored image from Boeing of what its 767 Tanker Transport will look like. (All photos and illustrations, Boeing, except where stated)

The number of armed forces around the world buying air-to-air refuelling tankers has steadily grown in recent decades. With many of the aircraft currently utilised, mostly Boeing 707 conversions and KC-135s, needing replacing and a number of other countries showing interest in this capability, both Boeing and Airbus have expended considerable resources to capture orders. The latter manufacturer has so far failed to win any competitions for new-build aircraft, while Boeing with its 767 Tanker Transport has been selected by three countries, Italy, Japan and the USA. Second-hand 767-300ERs are also in the running as the UK’s next tanker aircraft.

Boeing started working on the concept of using a Boeing 767 as a tanker in 1999 when it assembled a team to undertake preliminary design development. The following year wind-tunnel testing and proximity trials took place from NAS Patuxent River, Md, using a civilian 767-300ER and a Boeing F/A-18 Hornet which acted as a small category receiver and a Lockheed S-3B Viking as a medium-sized one. The aim of these tests was to check the viability of the 767 as a platform for aerial refuelling by ensuring receivers could fly smoothly in the aircraft’s wake, crucial for the precise close formation manoeuvring required of receiver aircraft. In June 2002 a USAF Boeing C-17A Globemaster III was also flown behind a -200ER to assess the effect on a large aircraft as well as one with a T-tail. The 767 received a good Cooper-Harper rating, the accepted industry scale for this subject. Indeed, Boeing claims that it performed better than any other aircraft in service today as a tanker. As a result, Boeing officially launched the programme in March 2001.

Above: A photograph taken during the proximity trials in June 2002 between a Boeing C-17A Globemaster III and a 767-200ER. This test flight helped ascertain the suitability of the 767 to act as a tanker.

767-200ER selected

Out of its own extensive product range Boeing believes the 767-200ER is the optimum choice due to its size and economical operating costs. It believes the

-200ER blends the right balance of range, fuel off-load and cargo capacity. It states a smaller aircraft would mean that more aircraft would be required to perform the same mission and be unable to support trans-oceanic fighter deployments. A larger aircraft, the company giving the Airbus A330 Multi-role Tanker Transport as an example, would not reduce the number of tankers needed and result in higher operating costs. In addition, they also found that any of the longer 767 variants would have insufficient ground clearance for a boom on take-off and landing. The sheer size of an aircraft is important as ramp space at deployed airfields may be limited and the strength of the tarmac may also be an issue. Boeing is keen to cite the type’s relatively soft ‘footprint’ in terms of weight, with it being lighter than the A330. It also highlights that many runways around the world would limit the amount of fuel a tanker can carry on take-off, however the 767 would provide greater operational capability by being able to uplift more fuel.

The manufacturer is offering the type in two basic models, the Convertible Freighter or Convertible Combi. The former can be operated with its cabin arranged for cargo or fitted out with seats, the Convertible Combi can do the same though also provides the option of a mixed load. Both versions can come with a large forward cargo door and a variety of in-flight refuelling options are available to meet a customer’s requirements. The full fit would be an aircraft with a refuelling probe and receptacle above the cockpit, two wing-mounted hose and drogue refuelling pods, a Boeing-designed boom under the tail as well as a centreline hose. Two additional fuel tanks can be fitted in the fuselage fore and aft of the wing, to increase fuel off-load. Any or all of these options can be provided.

The manufacturer has selected the Smiths Aerospace refuelling system which consists of a mission control system, a centreline hose-drum unit and wing pods. All aircraft fitted with a boom will use the RARO (Remote Aerial Refueling Operator Station) II system. This seats the boom operator behind the cockpit rather than at the back of the aircraft looking out of a window. Instead, remote cameras will be used to allow the boomer to see the receivers. This, according to Boeing, has a number of advantages. It greatly improves mission management through automated controls and provides better low-light refuelling capability. It also aides crew co-ordination by concentrating personnel in one area, plus by doing so it also reduces cost by not having to redesign the rear interior of the aircraft. A similar system, RARO I, is used by the Royal Netherlands Air Force McDonnell Douglas KDC-10s.

Above: A drawing illustrating the size difference between a Boeing 767-200ER and an Airbus A330-200.

Italy leads the way

The first customer to select the Boeing 767 Tanker Transport was Italy in July 2001. The Combi version with a large freight door has been selected, powered by General Electric CF6-80C2 turbofans. The Aeronautica Militare Italiana (AMI)/Italian Air Force has opted for its aircraft to be fitted with a boom, wing pods and centreline hose and drogue refuelling system. The contract for four aircraft to replace four Boeing 707-300 tankers was signed on December 11, 2002. The first aircraft will arrive from the Everett plant at Wichita, Kans, for completion in August 2003, with delivery scheduled for 2005. The remaining aircraft will be fitted out at Naples in Italy by Aeronavali. The final tanker will be handed over in early 2008.

The second country to join the programme was Japan which chose the type in December 2001. Contract finalisation for four aircraft is expected in early 2003. This will give the Japanese Air Self-Defence Force (JASDF) some degree of commonality due to it already having four 767-200ERs in service which are AWACS aircraft and designated E-767s. The Convertible Freighter variant has been selected using the same engine type as the AMI and the aircraft will be fitted with an air-refuelling boom. The first 767 tanker is due to be delivered in 2006. It appears that with this in mind the JASDF is to start training its pilots in the art of air-to-air refuelling as it was recently revealed that eight Japanese pilots using four

F-15Js will conduct the country’s first ever operational in-flight refuelling exercise with USAF Boeing KC-135s from Kadena AB on Okinawa. Prior to the Second World War Japan’s Imperial army and navy experimented with the concept though never managed to make it work operationally.

Above: An illustration of the interior of the Convertible Combi variant of the 767 Tanker Transport which has been selected by the USAF. The benefit of this version is the ability to carry a mixed load of passengers and cargo, as shown here.

USAF choose the 767

By far the biggest single customer for the 767 Tanker Transport will be the USAF. The Air Force’s interest in the aircraft stretches as far back as 1990 when an initial study was undertaken which confirmed the aircraft would be suitable as a tanker. More recently, in late 2001 Congress authorised the USAF to negotiate the lease of up to 100 aircraft to replace the Boeing KC-135E Stratotankers still in service. In March 2002 the USAF studied a proposal from EADS for the Airbus A330-200 as well as Boeing’s 767. The USAF decided the 767 Tanker Transport was the best option and in September last year gave it the designation KC-767A. Strangely, for the next tranche of orders past the initial 100 new tankers the USAF has confirmed to EADS that it will look again at the Airbus A330-200.

The USAF has decided its aircraft would be the Convertible Combi variant with auxiliary tanks to allow them to carry 202,000lb of fuel. They would be able to be refuelled by a receptacle and have a boom and centreline drogue. They would also have the latest cockpit, as designed for the 767-400. A more powerful auxiliary power unit (128 KVA) will be fitted which will be capable of coping with the extra sensors and communications equipment to be added at a later date for the ‘SMART tanker’ programme. The next stage development of the type’s refuelling capabilities, called Spiral 2 by the USAF, is intended to be the fitment of wing pods.

For the rest of this article please see the March issue.