© Airbus Military
A typical arrangement on a modern tanker aircraft providing AAR to a fighter jet. In this particular case, the crew from a 14º Stormo Boeing KC-767 of the Italian Air Force co-ordinate and monitor the refuelling of a Eurofighter Tyhpoon from 4º Stormo Caccia over the 'Romeo 21A' area off the NE coast of Italy
The KC-135 is by far the most numerous tanker ever built and probably what most people ‘see’ when someone mentions the word tanker. Operational service commenced on 30 April 1957 with the 93rd Air Refueling Squadron at Castle AFB, California. Designed to meet Strategic Air Command's requirement for a tanker/transport aircraft, 820 C-135 variants were built over a 10-year period, of which 749 were built for the USAF as KC-135A & B models.
another valuable asset in the air-to-air refuelling scenario. Combined with MPRS, the triple hose/drogue method makes it possible for two aircraft to be refuelled simultaneously on the two wing-tip drogues, but if the BDA on the rigid boom is in use then the wing-tip pods cannot be used due to an inadequate refuelling envelope clearance between the receiver aircraft. The standard KC-135 orbit speed when refuelling is 275 knots indicated air speed (KIAS), or Mach 0.78. The maximum for the high-speed boom between sea level and 29,400ft is 355 to 373 KIAS, with the maximum speed when using the BDA being between 225 to 305 KIAS. An example of the BDA can be seen in the image above, with a German Air Force Tornado IDS refuelling from a KC-135 Stratotanker.
fuel tanks, the KC-10 also has three large fuel tanks under the cargo floor, one under the forward lower cargo compartment, one in the centre wing area and one under the rear compartment. Combined, the capacity of the six tanks carries more than 356,000 pounds (160,200 kilograms) of fuel - almost twice as much as the KC-135 Stratotanker. Using its high-speed aerial refuelling boom, or its centreline hose and drogue, the KC-10 can refuel pretty much all U.S and allied military aircraft during the same mission.
transport more cargo pallets, carry more passengers and patients, and met the Air Force's ferry range requirement of 9500 nautical miles (which Boeing's offer did not). However, the contest was re-opened in July 2008 after Boeing's protest of the award to Northrop Grumman was upheld. The contract dispute led to a much-muted fact that the KC-45 was in fact a non-US aircraft and that the powers that be wanted to award the contract to Boeing no matter what, although this was obviously denied. But in the end, Boeing prevailed, and having won the second competition to fulfil the KC-X requirement, the KC-46A Pegasus came to fruition.
The Airbus A330-MRTT has brought air-to-air refuelling capabilities to a new level - enabling faster fuel offloads, with much larger capacities and cargo/passenger carrying capabilities than could ever have been dreamed of when the KC-135 was first introduced. Faster, quieter and much more comfortable for its crew, the A330-MRTT really is a huge step up in capability, so much so that it was initially chosen by the United States (in its Northrop Grumman KC-45 guise) as its new tanker aircraft before a change of mind resulted in the purchase of Boeing's KC-46A Pegasus - but that's a story we'll cover later!
McDonnell-Douglas KC-10A Extender
In the image above, this RAF Tornado GR4 takes on fuel, showing a typical hose and drogue system, with the 'basket' clearly visible
Returning 'home' after a gruelling mission into enemy territory to undertake a precision weapons strike on an enemy air-defence radar, your F-16 Fighting Falcon is in need of some gas to get you back to base. The eerie quiet of the cockpit is suddenly broken by the dulcet tones of the co-pilot on Exxon 001, a KC-135R Stratotanker from the 100th Air Refueling Wing (ARW), which is flying a racetrack pattern in support of the mission and just waiting to provide you with that much needed fuel.
At flight Level 220 (22,000ft), it’s pitch-black as you fly over deserted terrain with no concept of where the horizon is, relying solely on your cockpit instruments and the radio communications from the tanker aircraft to guide you in. Flying at 300 knots, you catch the first glimpse of the KC-135’s navigation lights in the distance and close in towards the ‘pre-contact’ position some 50 feet below and 50 feet behind the aircraft’s in-flight refuelling boom. As you continue to close on the KC-135 your F-16 starts moving around as it is buffeted by turbulence from the tanker aircraft. The ‘Boomer’ gives you clearance to close on the boom - skillfuly manoeuvring it into your F-16s receptacle, the JP-8 flowing at a rate of 1500lbs per minute into the tanks. No time to relax though, it still takes all your skill to maintain position behind the KC-135 until your fuel tanks are topped up.
It might be worth pointing out at this time that there is much more to air-to-air (AAR) refuelling than just rocking up at the local gas station to fill up as you would with your car. Extending range, increasing loiter time on station, and taking off with a larger payload are just a few of the advantages AAR provides. In the modern era, most large air arms consider in-flight refuelling as routine, with a wide variety of aircraft used to provide such service, some converted transport variants, some purpose built. Jetwash Aviation Photos takes a look at some of today's modern tanker aircraft.
The photograph left provides a nice example of the flight deck on the Boeing KC-767A, which is a far cry from that of the iconic, but ageing KC-135 Stratotanker. There is so much more space on the flight deck and not an analogue dial in sight. Despite the upgrades that the KC-135 has received over the years, it pales in comparison to the glass cockpit on the 767. For someone such as myself who has had the pleasure to fly with both, it's a bit like comparing Economy Class to Business Class, and it's a similar situation in the passenger/cargo hold. The KC-767 and other modern tankers such as the A330-MRTT have airline-type seating, making long overseas deployments a much more comfortable experience for the troops.
Embraer KC-390 Millennium
An Ejército del Aire (Spanish Air Force) KC-130H is seen landing at Gando Air Base, Gran Canaria, in 2017
Lockheed KC/MC-130 Hercules
The KC-46 is able to refuel any fixed-wing receiver capable aircraft, and is equipped with a modernized KC-10 refuelling boom, integrated with a proven fly-by-wire control system capable of delivering the fuel off-load rate required for large aircraft such as a C-5 Galaxy or B-52 Stratofortress. In addition, the Pegasus also has a hose and drogue capability that adds additional mission capability, independently operated from the high-speed boom system.
Embraer's KC-390 is the largest aircraft designed and built by the company, and one of the 'new kids on the block' as far as AAR is concerned. Two prototypes were planned by the programme. The first prototype was rolled out from the Embraer subsidiary plant, Embraer Defence and Security, at Gavião Peixoto, São Paulo on 21 October 2014, and flew for the first time on 3 February 2015. The KC-390 refuels other aircraft through its two wing-mounted probe and drogue pods delivering up to 1,500ltrs (400 US gal) per minute from a 35 tonne (77,000 lb) total fuel capacity. The KC-390 has been marketed as a jet-powered alternative to the Lockheed Martin C-130 Hercules, and as of early 2021, four aircraft had been delivered to the Brazilian Air Force, with a further 24 still on order.
However, the slow 230mph cruise speed of the KC-97 (seen photo, right) became a serious issue for the newer and faster jet-powered military aircraft entering service, often forcing them to slow down to connect with the tanker's boom, ultimately forcing the receiver aircraft in certain situations to slow down so much on approach to the tanker that they came very close to their stall speed.
Looking for a jet aircraft to provide the necessary higher speeds for the modern era, Boeing began receiving contracts from the USAF to build jet tankers based on the Boeing 367-80 airframe, resulting in what became the Boeing KC-135 Stratotanker. The KC-135’s high-speed boom used to refuel receiver aircraft is attached to the rear of the tanker aircraft, and has a gimbal to allow the boom to move with the receiver aircraft. The boom contains a rigid pipe to transfer fuel, which ends in a nozzle with a flexible ball joint. The nozzle mates to the receptacle in the receiver aircraft during
© Omega Air Refueling Services
Easily identifiable by its 6-bladed props, the KC-130J is the latest version of the Hercules tanker in service
The image above shows the retractable refuelling probe of an Italian Air Force Tornado in the extended position it would adopt when receiving fuel from a tanker aircraft
One of the newer KC-135s in the USAF inventory, the flightplan that day would see the aircraft conduct a 8.5hr mission across Europe into airspace off the coast of Libya during Operation Unified Protector, where they would be on constant alert, refuelling Dutch and United Arab Emirates F-16 fighters operating out of Decimomannu, Italy, as part of the NATO-led coalition during the Libyan civil war to oust Col. Muammar Gaddafi's regime from power.
So as to enable boom-equipped tankers to refuel receiver aircraft that require a hose and drogue method of refuelling, the Boom-Drogue Adaptor (BDA) was developed and can be attached to the end of the fixed boom. The BDA is 9ft (2.74m) of hose attached to the telescoping part of the boom by a swivel coupling; the hose terminating in a non-collapsible drogue basket. The BDA looks somewhat ungainly as it dangles from the end of the boom, but once in flight it becomes
Each individual aircraft provides different challenges to both the tanker and receiver aircraft. Two of the most difficult aircraft to refuel are the C-17 and the B-2, due to the large bow-wave they create in front of the aircraft. Their close proximity to the tanker causes a nose-down pitching movement in the tanker, which can disconnect the autopilot if the movement is too large for the trim to adjust it. A slower closure rate for larger aircraft can help negate the effects of the large bow wave, but trust me, having sat in the back of a KC-135 whilst refuelling a B-2 it is very noticeable, and you can literally feel the aircraft's nose dropping and then lifting - a very strange experience.
Strangely though, the F-16 also provides its challenges for inexperienced Boomers. Fighter-jocks have a habit of coming in fast when closing on the boom and quite often 'plant' the aircraft exactly where it needs to be - particularly experienced pilots with numerous connections under their belt. As the F-16 receptacle is halfway along the F-16's fuselage, the Boomer has to negotiate the canopy and antenna dotted atop the fuselage before 'dropping' the boom into its receptacle - not quite as easy as it appears, and the last thing you need is an impatient fighter jockey who needs gas. Things can get very messy, very quickly!
Its fast fuel-flow rate (up to a maximum of 3600 kg/min – 1200 US gal/min) makes the ARBS the most capable new generation boom system available. The second method available to the A330 are the two wing-mounted Cobham 905E refuelling pods that use the hose and drogue refuelling method. These enable the A330-MRTT to refuel any NATO or allied probe-equipped receivers such as the Eurofighter Typhoon, the Tornado, or the FA-18 Hornet. The third method available is via the Cobham 805E Fuselage Refuelling Unit (FRU), a removable hose and drogue unit that allows refuelling receivers with a different fuel type. This option allows for one fuel type to be
The C-130 Hercules was initially manufactured as a tactical airlifter back in the 1950s, and has since gone on to be produced in huge numbers, meeting a variety of missions such tactical airlift Search & Rescue, Maritime Patrol, Special Operations, Electronic Countermeasures, Close Air Support, fire-fighting, and of course Air-to-Air Refuelling; with over 2,500 built and operating in approximately 70 countries around the world - it truly is a workhorse. The current C-130J has been in production since 1998 and over 300 J-models alone are already in service.
In the late 1940s, General Curtis LeMay, commander of Strategic Air Command (SAC), asked Boeing to develop a refuelling system that could transfer fuel at a higher rate than had been possible with earlier systems using flexible hoses, resulting in the flying boom system. Between 1950 and 1951, 116 B-29s were converted by Boeing to KB-29, which eventually led to the world's first production aerial tanker, the KC-97 Stratofreighter, a version of the piston-engined Boeing Stratocruiser with a Boeing-developed flying boom and extra fuel tanks feeding the boom.
© Bram Marijnissen
Seen in the two images above are examples of buddy - buddy refuelling pods. In this particular case these ones are used by the Aeronautica Militare Italiana on their Panavia Tornados. The image left shows the hose-reel and basket exposed, with the HDU visible. The image right shows the front of one of the pods, with the small propeller that drives the winch used to reel the hose back into the pod, whilst the rear of the other pod can be seen showing the basket in its retracted position.
The AMI KC-767's load can be set up in three configurations (Combi, Cargo, or Passenger), with a 25,000kg (55,115 lb) total payload. For the cargo configuration, 19 NATO-standard military pallets can be fitted; whilst in passenger configuration, up to 200 passengers can be boarded together with their respective luggage. In the combi configuration, up to 100 passengers and 10 NATO-standard military pallets can be accommodated. The KC-767 also has an in-flight refuelling receptacle allowing it to be refuelled by another tanker, increasing its already impressive capabilities and range.
Whilst many people would assume that the KDC-10 is a variant of the KC-10 Extender, it is actually far from the truth, as they are very different aircraft. The KDC-10 is a militarised version of the McDonnell-Douglas DC-10-30 airliner and different to the KC-10 in that it does not have as much fuel capacity - although the KDC-10 does have a larger cargo carrying capacity.
Now entering service with the US Air Force is the Boeing KC-46A Pegasus, with the USAF planning for 179 of the new tankers to partially replace the ageing KC-10 and KC-135 fleets. However, the KC-46 has been beset with problems. It was intended that first deliveries of the new aircraft would commence in 2016, but the USAF did not receive its first KC-46 until 2019. As well as coming in extremely late on its expected in-service schedule, the aircraft then suffered issues
As can be imagined though, little is known for sure about the exact details of the Israeli KC-707 systems. As with the KC-135, the aircraft are kitted out with a high-speed boom at the rear of the aircraft and are capable of refuelling the country's F-15 and F-16 fighters, as well as the KC/C-130 Hercules tanker/transports. It is believed that some form of camera system is in place to assist the refuelling process from a control station within the aircraft. In the image above what appears to be a rearward facing camera can be seen on the lower fuselage just in front of the boom.
High-Speed Boom system
'Nobody Kicks Ass Without Tanker Gas’ (NKAWTG) is an acronym used within the US Air Force tanker community, and is rumoured to have been started by the 305th Air Refueling Wing at Grissom AFB, Indiana, way back in 1984.
Simply put, without the support of in-flight refuelling aircraft, pretty much nothing would get done! Strike missions, long-range transport, special forces, and QRA - all regularly require air-to-air refuelling to complete the mission. And so, whilst the thought of being an aerial gas station driver may not appear that glamorous to most pilots, it’s a vital piece in the jigsaw of today’s modern air arm.
A Royal Malaysian Air Force KC-130H Hercules from 20 Squadron, with the hose and drogue refuelling pod clearly visible on the outer wing pylon
The current version of the Il-78 in service with the Russian Air Force today is the Il-78M, a dedicated, non-convertible tanker (meaning it cannot be used to haul cargo), featuring a third fuel tank fitted inside the cargo bay, increasing its total fuel capacity to 138 tonnes. The Il-78M (photo, left) in service with the Russian Aerospace Forces (VKS) use the Zvezda UPAZ-1M refuelling pods mounted on the outer wings, and one on the portside of the aircraft at the rear of the fuselage. The air-to-air refuelling process is controlled by an operator located at the flight engineer’s station in the cockpit.
The A310-MRTT is in service with the German and Canadian Air Forces. The Luftwaffe took delivery of seven Airbus A310s from 1991, with two later being converted to MRT (Multi-Role Transport) versions in June 1999, which along with a further two standard aircraft were subsequently converted to MRTT (Multi-Role Tanker Transport) between 2002 and 2005.
The wing-mounted hose and drogue pod (photo, left) and high-speed boom (photo, right) on an Italian Air Force Boeing KC-767A
The two photos above illustrate a typical scheme worn by Israeli Air Force Boeing 707s. Wearing no national markings, no squadron markings and no national flag, to the layman it would just appear to be a rather non-descript airliner. The only giveaway is the high-speed refuelling boom fitted at the rear of the aircraft's fuselage - giving away its identity as a tanker. Although the IAF 707s have worn a variety of colour schemes over the years they have all been rather vague in giving away any clues as to who they belong to. In recent years at least one was painted in a matt overall grey scheme although again, no national markings were applied, but it seems the scheme above has been generally adopted across the fleet.
Seen left, a NATO Boeing E-3A AWACS (Airborne Warning And Control Systems) aircraft gets replenished by a KC-135R belonging to the 151 Air Refueling Wing (ARW), Utah Air National Guard. The 151st ARW is just one of several Guard units that has deployed to Geilenkirchen, Germany, since 1994 for a period of two weeks at a time to help train the AWACS aircrews, allowing them to perform their airborne surveillance and command and control missions. This particular E-3 was topping up its fuel prior to going Oceanic across 'the pond' to NAS Norfolk, Virginia.
The new KC-130J builds on proven tanker designs whilst taking full advantage of tremendous technological and performance improvements inherent in the basic C-130J aircraft. The MC-130J Commando II is a multi-mission combat transport/special operations tanker, assigned to the Air Force Special Operations Command (AFSOC). The MC-130J provides AFSOC with a modern aircraft capable of worldwide employment for missions requiring clandestine single or multi-ship, low-level aerial refuelling of Special Operation Forces helicopter and CV-22 Osprey aircraft and/or infiltration, re-supply and exfiltration by airdrop, or landing on remote airfields.
A total of 60 KC-10 aircraft were purchased by the US Air Force (USAF), 20 of which were later modified with the addition of wing-mounted pods (MPRS), further enhancing their aerial refuelling capabilities. The KC-10 is currently operated by the 305th Air Mobility Wing at Joint Base McGuire-Dix-Lakehurst, N.J.; and the 60th Air Mobility Wing, Travis Air Force Base, Ca. Air Force Reserve Associate units are also assigned to the 349th Air Mobility Wing at Travis, and the 514th Air Mobility Wing at JB McGuire-Dix-Lakehurst, both of which use the KC-10s assigned to the active service units at each base. July 2020 saw the first retirement of a USAF KC-10, with the fleet slated for replacement by the Boeing KC-46A now coming into USAF service. Although the KC-10 has only served with the US Air Force to date, a small number of commercial DC-10 airliners from which the type was devised, have been converted to aerial refuelling aircraft and look very similar, although in actual fact are very different.
Ilyushin IL-78 'Midas'
There are two different AAR systems used by today’s air arms. The photos above depict a Royal Moroccan Air Force Lockheed KC-130H Hercules using the hose and drogue (left), and a US Air Force Boeing KC-46A Pegasus equipped with a rigid high-speed boom (right)
One of the four KC-767A on Italian Air Force strength is seen at its home base of Pratica di Mare on the outskirts of Rome
The A400M is the only tanker that can refuel the entire range of probe-equipped military aircraft at their preferred speeds and altitudes. This also extends to rotary-wing aircraft, as demonstrated in 2019 with the first such air-to-air refuelling contacts using an Airbus H225M helicopter. Thanks to its powerful turboprops, the A400M can fly both at low speeds and low altitudes to refuel slow receivers, as well as at higher speeds and altitudes of about 300 knots and altitudes around 25,000 ft, which are typically used for refuelling fast-jets such as the Eurofighter or larger aircraft (such as the C295) or even another A400M for buddy refuelling.
Cobham/Flight Refuelling Ltd provide the Multi-Point Refuelling System (MPRS) pods (commonly known as Mippers) to allow for the aerial refuelling of NATO and US Navy/Marines Corps aircraft that use a hose and drogue refuelling method rather than the rigid boom system adopted by the US Air Force on its tanker aircraft. The MPRS pods (photo, left) are attached to each wing-tip of the aircraft, and have a retractable 74ft (22.5m) hose. On command, the hose and drogue winch out from the pod. When equipped with the MPRS, the KC-135R can refuel both USAF aircraft and Navy/Marine/NATO aircraft during a single mission. The fuel offload is programmed in before the hose is extended, the receivers come and latch on to the basket and once they hit the fuel mark entered, it stops pumping fuel automatically.
© Vince Horan
The AMI KC-767A is a convertible combi, meaning it can be set up in an all-passenger configuration, all cargo, or a combination of passengers and cargo, whilst still maintaining its AAR capability. The KC-767 has an aerial refuelling boom with a remote aerial refuelling operator station, as well as wing-mounted pods and a centreline hose and drogue system - this configuration allowing for the refuelling of all existing types of aircraft, both fighters and transports. The 767’s refuelling boom has a fuel-flow capacity of up to 900 gallons (4,091 litres) per minute. The centreline hose & drogue has a capacity of up to 600 gallons (2,727 litres) per minute, whilst the wing-tip pods have a capacity of up to 400 gallons (1,818 litres) per minute.
In 2014, the Brazilian Air Force (FAB) signed a firm order for 28 Embraer KC-390 aircraft and initial logistical support. Produced at the Gavião Peixoto factory, in São Paulo state, Embraer's KC-390 was granted Type Certification in 2018, when it also achieved Initial Operational Capability (IOC).
Exact details of the H-6U are obviously hard to establish due to the secrecy China has in respect of its military, but the H-6U is believed to have a maximum fuel load of 37 tons and is able to refuel two aircraft simultaneously at the same time. The PLA later took delivery of a small number of Ilyushin Il-78 aircraft and is currently developing a tanker version of the indigenous Xian Y-20 transport, although the Xian HU-6 still remains in service.
The Fuerza Aérea de Chile (FACh - Chilean Air Force) operated a small number of second-hand Boeing 707 aircraft for many years before finally getting their hands on three ex-US Air National Guard KC-135E aircraft. The E-model Stratotankers were originally built as A-models, which were later re-engined with Pratt & Whitney JT3D turbofan engines salvaged from withdrawn Boeing 707/720 airliners. Supplied to Guard and Reserve units, 161 aircraft underwent the E-model re-engining programme, giving the aircraft an additional 20,000lb thrust, whilst also reducing engine noise, smoke emissions and fuel consumption. Two of the FACh aircraft, one of which is seen in the photo right, still operate today with 10 Grupo at Santiago.
Although originally designed as a transport aircraft and not as an aerial refueller, the KC-390 can carry out various missions including, humanitarian support, medical evacuation, search and rescue, forest fire-fighting, cargo/troop transport and launch capabilities. Its aerial refuelling capability is provided by the use of two Cobham 912E Wing Refuelling Pods, which is an advanced bespoke design solution for the KC-390 to meet the aircraft's high-performance criteria, including its ability to satisfy a wide number of receivers at extended ranges. Orders have so far been placed by Brazil, Hungary and Portugal.
first non-stop round-the-world flight in 1949, made possible by four aerial refuellings from four pairs of KB-29M tankers of the 43d ARS.
The Korean War saw extended use of operational air-to-air refuelling for the first time, the tanker fleet becoming an essential cog in major air forces around the world. The first use of aerial refuelling in combat took place during the Korean War, involving US Air Force F-84 fighters refuelling from converted Boeing KB-29s using the hose-and-probe system.
The View from the Boomer's position in a KC-135. Note the different positioning of the refuelling receptacle on the receiver aircraft (F-15 left and F-16 right)
As mentioned, the refuelling hose connects to a Hose Drum Unit (HDU) mounted in the aircraft fuselage or on wing-mounted pods, and when not in use the hose is reeled completely into the HDU. The image right shows the Cobham Mission Systems arrangement mounted in an under-wing pod on a US Marine Corps Lockheed Martin KC-130J Hercules. The KC-130J has two such pods, which can each transfer up to 300 gallons per minute to two aircraft simultaneously, allowing for rapid cycle times of multiple-receiver aircraft formations - a typical tanker formation being a flight of four aircraft, which can all be refuelled in less than 30 minutes.
transferred from wing-mounted pods, whilst an alternative fuel type is dispensed from the FRU for large probe-equipped aircraft such as the A400M or C295, also having a higher fuel offload rate of 1800 kg/min – 600 US gal/min than the wing-mounted pods.
A US Air Force B-2A Spirit refuels from a Boeing KC-135R Stratotanker during a deployment to the UK
© Airbus Military
A KC-46A is seen refuelling an A-10C from the 23rd Fighter Group, closely watched by an F-16 from the 416 Flight Test Squadron at Edwards Air Force Base
Nobody Kicks Ass Without Tanker Gas
Japanese Air Self-Defence Force KC-767J (photo, above) do not have wing-mounted refuelling pods
The KC-130J offers a 57,500-pound fuel offload capacity using wing and external tanks while in the air. The KC-130 is equipped with a removable 3,600-gallon aluminium fuel tank that is carried inside the cargo compartment providing additional fuel when required. The aircraft is ready to fuel fixed or rotary-wing aircraft using the standard hose and drogue. The two wing-mounted refuelling pods each transfer up to 300 gallons per minute to two aircraft simultaneously, allowing for rapid cycle times of multiple-receiver aircraft formations (a typical tanker formation of four aircraft in less than 30 minutes). When more fuel is needed, an additional 24,392 pounds of fuel can be off-loaded from a specially configured internal fuselage tank.
Boeing KC-46A Pegasus
The McDonnell-Douglas KC-10A Extender is in service with USAF Air Mobility Command. Although the KC-l0's primary mission is aerial refuelling, as with most of its counterparts it can combine the tasks of a tanker and cargo aircraft. The KC-10 can transport up to 75 people and nearly 170,000 pounds (76,560kg) of cargo a distance of about 4,400 miles (7,040km) unrefuelled. In addition to the three main wing
Now coming into service at Eindhoven and Koln, the NATO MMF is the latest recipient of the popular A330-MRTT, replacing the current A310-MRTT and KDC-10 aircraft in service
The A330-MRTT is one of the new breeds of tanker aircraft, specifically designed for its role. It is currently in service with Australia, France, Saudi Arabia, Singapore, South Korea, United Arab Emirates, United Kingdom, and NATO’s Multinational Multi-Role Tanker and Transport Fleet (MMF). Generally, the aircraft are similar in most respects, and are what's known as 3-point tankers; meaning that they have three methods of refuelling receiver aircraft based upon their specific requirements.
Based on the commercial Boeing 767-200ER airliner, the KC-767 was produced in very small numbers, with just four aircraft in service with the Aeronautica Militare Italiana (AMI – Italian Air Force), and four with the Japanese Air Self-Defence Force (JASDF). The AMI aircraft are equipped with both a high-speed boom and wing-tip mounted hose and drogue pods, whilst the JASDF aircraft are only equipped with a high-speed boom. The Colombian Air Force also
The Royal Air Force A330 Voyagers lack the high-speed boom of other A330-MRTT versions - the aircraft in the photograph right, clearly showing the smooth lines at the rear of the aircraft where the boom would normally be. This particular aircraft, serial ZZ336, carries a non-standard livery and is used as a VIP transport for the UK Royal Family and high-ranking Government figures on official duties. The aircraft does however retain its full AAR capability and regularly conducts such flights from its base at RAF Brize Norton.
on quality control that saw deliveries delayed yet again. But let's be honest here, the KC-46 probably shouldn't even be entering service with the US Air Force, as Boeing initially lost the KC-X competition to Northrop Grumman's KC-45 aircraft, which was based on the Airbus A330-MRTT. At the time the US Air Force stated that the KC-45 "Offers significant advantage in the important areas of aerial refuelling and airlift, and represents superior value to the government." In comparison to Boeing’s offer, the KC-45 could deliver more fuel at greater ranges, was more fuel efficient, could perform more refuelling operations faster, featured a larger boom envelope twice the size of its competitor, could take-off with more fuel from a 7000ft runway,
A US Marine Corps F/A-18D Hornet takes on fuel over the Arizona desert during a Weapons & Tactics Instructor course at Yuma
Air-to-air refuelling can be done either through two wing-mounted hose and drogue under-wing refuelling pods or through a centreline hose. The two hose and drogue under-wing refuelling pods can each provide a fuel flow of up to 400 US gal/1,200 kg per minute to receiver aircraft. The centreline hose and drum unit (HDU) provide a higher fuel flow of some 600 US gal/1,800 kg per minute. The A400M is the only tactical tanker offering a third refuelling point for large aircraft refuelling and as an alternative to pods. To monitor day and night air-to-air refuelling operations, the A400M can be fitted with three cameras controlled from the cockpit by the co-pilot, suppressing the need for visual observers.
The Il-78M-90A is being manufactured by Ilyushin and Aviastar-SP, both part of United Aircraft Corporation (UAC). The -90A features an enhanced propulsion unit and modern avionics, an enhanced payload capacity and a modified wing assembly incorporating two fuel tanks with a capacity of 111,940ltrs. The fuselage has a diameter of 4.8m and is configured to carry approximately 50,300ltrs of fuel, while a large cargo ramp at the rear provides the aircraft with an airdrop capability. The modular airframe can also be converted to support other roles such as fire-fighting and transportation. The first Il-78M-90A prototype was rolled out on 29 November 2017, and performed its maiden flight on 25 January 2018.
Today’s R-model is a re-engined variant designed to give a much-needed power boost, along with increased service life, better performance and fuel economy, together with reduced maintenance costs and compliance with modern day noise restrictions. After assessment of various engines, the General Electric/SNECMA CFM-56 was selected and the first KC-135R aircraft was rolled-out at Boeing's Wichita modification facility on 22 June 1982, with the first unit (384th ARW at McConnell AFB) receiving its aircraft in June 1984. Numerous other modifications took place during the upgrade, including larger stabilisers, revised wing leading edges, wing and fuselage reinforcements, new yaw damper and rudder actuators and strengthened landing gear. Each CFM-56 engine provides an impressive increase in thrust of 22,000lb compared to the A-models original J-57 engines, which produced only 13,750lb each. Although the Stratotanker is still the primary tanker in USAF service, it is now gradually being replaced by the Boeing KC-46A. The KC-135 serves/served with the United States, Chile, France, Singapore and Turkey.
Despite being by far the most numerous tanker aircraft ever built, very few served outside of the US Air Force or National Guard/Reserve units. France was the first overseas air arm to receive the Stratotanker when it ordered 12 in 1962. Designated the C-135F in the Armée de l'Air, they differed to the USAF aircraft in having a metal cargo floor (as against the wooden one in USAF aircraft) and originally having no upper-deck fuel tank. Later re-engined with the SNECMA/CFM-56 engine as per the US aircraft, they were re-designated C-135FR. During 1993/94 the French tankers were equipped with Multi-Point Refuelling System (MPRS) pods or Mippers, on outer wing pylons. An example can be seen in the photo (left), with the MPRS clearly visible.
Both the KC-130 and MC-130 have been in production/service for many years in a number of variants – the latest being the KC-130J and the MC-130J, both of which are variants of Lockheed Martin’s C-130J ‘Super’ Hercules. The C-130 entered production way back in the 1950s as a tactical transport, subsequently being produced in a number of specific roles which have included Search and Rescue (SAR), tanker, gunship, Electronic Countermeasures (ECM) and Special Operations variants.
Multi-Point Refuelling System (MPRS)
Buddy - buddy in-flight refuelling is generally used by tactical aircraft such as the McDonnell-Douglas F/A-18 Hornet seen in the image, right. The US Navy in particular have utilised this method to support Carrier Air Wing operations on board its aircraft carriers where the support of large tanker aircraft is out of the question.
When aircraft such as the F/A-18 are used to provide air-to-air refuelling to other tactical aircraft, the external stores pylons are loaded with additional drop tanks, which contain fuel available to offload to the receiver aircraft. The Buddy - Buddy refuelling pod is normally mounted on the central fuselage weapons pylon on the Hornet, with the drop tanks mounted on the wing-mounted weapons pylons.
The A330-MRTT in Royal Air Force (RAF) service is known as the Voyager, and differs from the ‘standard’ A330-MRTT in that they do not have the high-speed boom. Two versions serve with the RAF - the Voyager KC2, equipped with a pair of Cobham 905E underwing hose and drogue pods for refuelling fast jets; and the Voyager KC3, which has an additional Cobham 805E Fuselage Refuelling Unit centreline hose for refuelling larger aircraft.
Air Force, the aircraft has also been ordered by Japan and Israel. The first unit to complete transition from the KC-135 to the KC-46 is surprisingly a Guard unit, that being the 157th Air Refueling Wing, at Pease Air National Guard Base, New Hampshire. The unit took delivery of its 12th and final aircraft on 5 February 2021, 18 months after delivery of its first aircraft.
The system also functions without the fuselage tank, so the cargo compartment can be used for cargo on the same mission, giving the aircraft even greater flexibility. The KC-130J provides for the rapid ground refuelling of helicopters, vehicles and fuel caches at 4,018 pounds per minute.
The Xian H-6 tanker was the first aerial refuelling aircraft developed by the Peoples Republic of China (PRC). The aircraft is a development of the H-6 bomber, itself a licence-built Chinese copy of the Russian Tupolev Tu-16 Badger bomber. China commenced research into producing an aerial refuelling aircraft in 1988, with the H-6 selected as the platform. The PRC’s first successful aerial refuelling was finally made in December 1991, with the first refuelling regiment
Two high-bypass turbofans power the KC-46A to take-off at gross weights up to 415,000 pounds. Nearly all internal fuel can be pumped through the boom, drogue and wing-mounted aerial refuelling pods. The centreline drogue and wing refuelling pods are used to refuel aircraft fitted with probes. MPRS configured aircraft will be capable of refuelling two receiver aircraft simultaneously from the under-wing pods. A cargo deck above the refuelling system can accommodate a mixed load of passengers, MEDEVAC patients and/or cargo. In addition to the US
On 12 December 2020, an order for 10 Il-78M-90A was signed, with production starting in 2021. The Il-78M-90A becomes the first refuelling aircraft produced in Russia in the post-Soviet era and will eventually become the VKS’s primary in-flight refuelling aircraft.
The first Embraer KC-390 was delivered to the FAB at Anápolis, on 4 September 2019, for the 1st Troop Transport Group (1st GTT). The KC-390 was developed as a joint project between the Brazilian Air Force and Embraer to set new standards for efficiency and productivity in its class. Just over a year after its service introduction, the KC-390 participated in its first international exercise - in the United States at Alexandria Airport, Louisiana, close to the Fort Polk, for exercise Culminating.
The History of Air-to-Air Refuelling
© Bram Marijnissen
With a basic fuel capacity of 63,500 litres (50,800 kg), which can be even further increased with additional cargo hold tanks, the A400M is the most capable tactical tanker on the market. Airbus completed certification flight tests for the A400M Cargo Hold Tanks (CHT) refuelling unit in 2019, taking a major step toward the aircraft’s full certification for aerial tanker duties.
An Indian Air Force Il-78MKI seen during a deployment to France in June 2010
Boeing KC-135 Stratotanker
formally established in 1997 at the Guangzhou Military Area Command (MAC). Two models of the H-6 aerial refuelling aircraft were produced, the H-6U of the Peoples Liberation Army (PLA) Air Force Air Force and the PLA Navy's H-6U(D). China's HU-6 tanker conversion was the result of a Memorandum of Understanding signed with FRL in the UK, in 1986. The result of this was an adaptation of the H-6 design with two indigenous pylon-mounted China Institute of Aero Accessories RDC-1 hose and drogue pods resembling FRL Mk.32 pods.
With the break-up of the Soviet Union, 20 Il-78M aircraft from the 409th SAP at Uzin Air Base were transferred to the Ukrainian Air Force, although they were all stripped of their in-flight refuelling capability and were used purely as transport aircraft, with a few later being sold. The Il-78 in its current form serves with Russia, Algeria, China (PRC), India, Libya and Pakistan. Many of the export versions differ to those in service with the VKS, with for example the Indian Air Force Il-78MKI using Israeli-built refuelling pods as against the Zvezda UPAZ-1M pods.
A close-up of the refuelling pod mounted on the wing of an AFSOC MC-130J Hercules
There are a variety of different pods used on the KC/MC-130
operates a single KC-767, but unlike the Italian and JASDF aircraft it was not produced by Boeing, but is in fact a former civilian airliner that was converted by Israeli Aircraft Industries (IAI), and lacks a boom, only operating with wing-tip mounted hose and drogue pods.
The only other country to use the A310 as a tanker was Canada, which purchased five A310 aircraft. In 2008, two of the five CC-150 Polaris, as the A310 is known in Canada, operated by 437 Squadron of the Royal Canadian Air Force (RCAF), were converted to air-to-air refuelling tankers, enabling them to refuel the RCAF fleet of CF-18 Hornets. The CC-150T Polaris tankers are capable of ferrying a flight of four CF-18 Hornets non-stop across the Atlantic Ocean, off-loading 80,000 pounds of fuel to receiving aircraft over a 2,500 nautical mile leg (4,630 km). Known as the CC-150T, the aircraft has hose and drogue pods under the wings.
Although the RNLAF KDC-10s are currently being withdrawn from service, both aircraft have been purchased by the US company, Omega Air - the first aircraft arriving in San Antonio, Texas, on 4 November 2019. Omega has operated a small fleet of Boeing 707 tanker aircraft for almost 20 years now and will expand its capability further with the KDC-10s, which will also be the company’s first boom-equipped aircraft. To date, Omega have provided AAR for US Navy and Marine Corps aircraft using Boeing 707 aircraft and a single KDC-10 which is not boom equipped, but with the ability of the 'new' KDC-10 aircraft to refuel using the boom, Omega will now be able to refuel US Air Force aircraft.
The Hose and Drogue system
Flight Refuelling Ltd (FRL) in the United Kingdom realised that the early looped-hose system in use left a lot to be desired and began work on an improved system now commonly called the hose-and-drogue. In post-WWII trials the Royal Air Force (RAF) used a modified Avro Lancaster employing the hose-and-drogue system, with a modified Gloster Meteor F.3 fighter fitted with a nose-mounted refuelling probe. On 7 August 1949, the Meteor, flown by FRL test pilot Pat Hornidge, remained airborne for 12 hours and 3 minutes, successfully receiving 2,352 imperial gallons of fuel in ten refuellings from the Lancaster. The modern hose-and-drogue method employs a flexible hose that trails from the tanker aircraft. The drogue, sometimes called the basket, is a fitting resembling a shuttlecock, attached with a valve to the end of the hose.
A RCAF CC-150T Polaris refuelling a CF-188A Hornet
The Russian built four-engine Ilyushin Il-78 tanker is designed principally from the Il-76 transport aircraft, and has the NATO reporting name Midas. The maiden flight of the Il-78T took place on 26 June 1983, entering service with the Voyenno-Vozdushnye Sily (VVS-Soviet Air Force) in 1984 - the Soviet Union adopting the hose and drogue method to refuel its fighter, bomber and transport aircraft.
Designed from the outset to be a dual-role transport and tanker aircraft, the A400M provides air forces with a cost-effective way to acquire an air-to-air (AAR) refuelling capability in addition to a versatile logistic and tactical airlifter. The standard A400M aircraft has much of the equipment and software provisions for two-point air-to-air refuelling operations already installed as standard. Any A400M can be rapidly reconfigured to become a tactical two-point tanker able to refuel probe-equipped receivers at their preferred speeds and altitudes.
The Airbus A330-MRTT can carry up to 111 tonnes of fuel, the highest capacity of any tanker aircraft. With the capacity to off-load 50,000kg of fuel to a wide range of receiver aircraft, the A330-MRTT can deploy fighter aircraft over long distances and is capable of supporting the deployment of four fighter aircraft plus 50 personnel and 12 tonnes of freight over 5,200km (e.g., From Europe to Afghanistan). Alternatively, a single A330-MRTT can carry a maximum payload of up to 45 tonnes; such as 300 Passengers; or a MEDEVAC cabin layout with 40 stretchers, 20 seats for medical staff and 100 passengers, together with 37 tonnes of equipment in the lower cargo deck. The Airbus Defence & Space Aerial Refuelling Boom System (ARBS), is used for receptacle-equipped aircraft such as the F-16 Fighting Falcon and F-35A Lightning II.
An F/A-18 Hornet refuelling using the hose and drogue method
Based on the A310-300C commercial airliner, structural strengthening along with a cargo door in the port forward fuselage gives the aircraft a capacity of up to 214 passengers, or 36 tonnes of freight stored on the main deck or in the lower cargo holds (or a combi passenger/freight mix), or 56 stretchers and six intensive care patients. The A310-MRTT is equipped with a hose and drogue refuelling pod on each wing-tip, and is also fitted with additional fuel tanks giving it a combined fuel capacity of 28 tonnes, similar to the KC-135R. The aircraft is still in service as of 2021, although the Luftwaffe is currently beginning withdrawal of the fleet in favour of the larger Airbus A330-MRTT that is forming as part of the NATO MMF at Eindhoven, Netherlands, and Cologne, Germany - the MMF providing a far more modern and cost-effective option to the Luftwaffe, by sharing the day-to-day costs of running a fleet of tanker aircraft between several nations.
A Royal Saudi Air Force Airbus A330-MRTT seen on finals
The Saudi's have six aircraft in service with 24 Squadron at Prince Sultan Air Base, Al Kharj
Capt. L. Smith and Lt. JP. Richter receiving the first mid-air refuelling on 27 June 1923
Inside the A330-MRTT, illustrating the modern and spacious environment that crews experience in comparison to older aircraft such as the KC-135
A close-up of the MPRS (left) and the high-speed refuelling boom (right) on a US Air Force Boeing KC-135R Stratotanker
A buddy pod is an external pod mounted on an aircraft hardpoint that contains a hose and drogue unit (HDU). Buddy pods allow fighter / bomber aircraft to be configured for buddy-buddy tanking of other aircraft. This allows an air combat force without dedicated tanker support such as a Carrier Air Wing to extend the range of its strike aircraft. Cobham produces a range of buddy refuelling pods which provide a fast-jet tanking capability that is particularly effective for carrier based naval operations, or the defence of extensive national boundaries. Currently used on aircraft such as the F/A-18,
'Boom 0r Hose' - There are two primary systems used by today’s combat aircraft; the High-Speed Boom, and the Hose and Drogue – with most air arms using one or the other, although some air arms/countries use both systems due to the fact that they operate receiver aircraft from different manufacturers, which results in the necessity to use a mix of systems. For example, aircraft built for the US Air Force use the high-speed boom system; whilst those built for the US Navy/US Marines Corps along with aircraft manufactured by European constructors, use the hose and drogue. So, for a country such as Saudi Arabia, this means equipping their Airbus A330-MRTT tankers with both systems - using the hose and drogue for its UK-built Tornados and Typhoons, and a high-speed boom for their US-built Boeing E-3 Sentry and F-15 fighter aircraft.
Tornado and the Dassault Super Etendard of the French Aeronavale seen above. The pods can be fitted either under the wing or under the fuselage, with Cobham currently planning to provide buddy-buddy refuelling systems suitable for the latest 5th generation fighter aircraft and also unmanned aircraft.
An aircraft that doesn’t readily spring to mind when discussing tankers is the Lockheed Martin C-130 Hercules, which in its KC-130 and MC-130 format both provide an air-to-air capability. In fact, the Hercules has been able to provide a refuelling capability since 1962 when the KC-130F entered service with the US Marine Corps. The KC-130 is a designated tanker/transport aircraft, whilst the MC-130 is a special operations variant which also carries an AAR capability.
Now receiving their A400Ms is 20 Squadron at Brussels-Melsbroek, replacing the C-130 Hercules in Belgian Air Force service
Of note is that the first aircraft delivered (CT-01, photo above left) wears Luxembourg national markings
Two DC-10 aircraft were purchased by the Royal Netherlands Air Force (RNLAF) in June 1992, having been sourced from the civil airline Martinair. They became operational in 1995 with 334 Squadron at Eindhoven. Both aircraft were converted to the tanker/transport role, with the installation of a refuelling boom and a Remote Air Refuelling Operating (RARO) control station, which is located directly behind the aircraft’s cockpit. One aircraft was withdrawn in 2020, with the second due to be withdrawn as the NATO MMF A330-MRTTs come on strength, the first of which arrived at Eindhoven in June 2020.
The KDC-10 is able to fly with maximum of 112 tons of fuel with more than 40 tons of cargo simultaneously, pumping approximately 1,750 litres of fuel per minute from the tanker. As mentioned, air-to-air refuelling is carried out by the RARO system, which has five cameras mounted externally on the aircraft fuselage that transmit a 3D image back to the cabin, where the refuelling is monitored and controlled from.
Air-to-air refuelling (AAR), aerial refuelling, in-flight refuelling, tanking – it’s called many things, but fundamentally it’s all the same. In the modern era AAR is pretty much taken for granted as a part of everyday operations, but its impact on today’s modern air arm is incalculable. Without it, the impact on many of the recent ‘air wars’ that have taken place would have been far reaching – resulting in more losses to aircraft and longer conflicts, with the inevitably higher losses of aircrew and the subsequent psychological impacts.
Some of the earliest experiments in aerial refuelling took place in the 1920s, consisting of two aircraft flying in formation, with a hose running down from a hand-held fuel tank on one aircraft and placed into the fuel filler of the other. The first mid-air refuelling between two planes occurred on 27 June 1923, between two DH-4B biplanes of the United States Army Air Service - with similar trials taking place at the Royal Aircraft Establishment in the UK, and also by the Armée de l'Air in France.
Rather than a retractable probe such as that fitted to the Panavia Tornado illustrated in the photos previously, many aircraft that use the hose and drogue method of air-to-air refuelling have a fixed in-flight refuelling probe. The French aerospace company Dassault Aviation are one such aircraft manufacturer that adopted the fixed probe for its fighter aircraft, a formula which it continues to this day with its Rafale fighter.
Seen left is a Spanish Air Force Dassault Mirage F1, with the rather ungainly probe clearly visible just in front of the cockpit. The primary benefit of a fixed probe is that it does not have any complex folding mechanisms that can be prone to failure - potentially leading to loss of the aircraft due to insufficient fuel.
fuel transfer, toggles retaining the probe in receptacle during fuel transfer. The boom has flight control surfaces that are arranged in a V-tail configuration that are used to 'fly' the telescopic boom. The control services are actuated hydraulically and controlled by the boom operator (Boomer) using two control sticks. To complete an aerial refuelling, the tanker and receiver aircraft rendezvous in formation, the aircraft moving to a position behind the tanker, aided by director lights and radio communications with the boom operator. Once in position, the Boomer extends the boom to make contact with the receiver aircraft and once in contact, fuel is pumped through the boom.
Although it has obviously been developed and improved over the last 60+ years, the high-speed boom still pretty much exists in the same format as that designed for the KC-135. US aircraft such as the McDonnell-Douglas KC-10 and Boeing's latest AAR aircraft, the KC-46A Pegasus, having booms that are very similar in appearance and operation to the original Stratotankers'.
The KC-707 aircraft in service were all converted from retired Boeing 707-300 commercial airliners. Similar in appearance to the KC-135 Stratotanker, the KC-707 has served with a number of air forces around the world and in various different guises - including Brazil, Canada, Chile, India, Israel, Italy, Pakistan, South Africa and Spain. Most have subsequently been withdrawn due to their age and in most cases replaced with more modern aircraft.
The Türk Hava Kuvvetleri (THK - Turkish Air Force) purchased seven A-model Stratotankers that were in storage at AMARG and had them converted to R-models prior to delivery in 1997/98. One of the aircraft is seen in the image left, photographed at Izmir. The Turkish aircraft have the Pacer-CRAG (Compass, Radar And Global) positioning system fitted, which eliminated the need for a navigator, as well as the the Global Air Traffic Management (GATM) avionics system.
Ω OMEGA Air Refueling Services
Airbus A400M Atlas
Probably the largest operator of the KC-707 was/is the Israeli Air Force (IAF), with the first two entering service during the Yom Kippur War in October 1973 - with five aircraft on strength by 1974. From 1983 onwards, the Boeing's began to conduct air-to-air refuelling of IAF fighters. It is hard to put an exact figure on the number of 707s that have been operated by the IAF, as the fleet has been in a constant state of flux over the years.
The IAF still retain a number in its inventory with 120 Squadron at Nevatim, equipped with additional fuel tanks of 30,000lb capacity installed in the former passenger cabin, giving them almost 190,000lb of fuel available for offload. The aircraft are believed to feature an electro-optical system that enables the operator to control and guide the refuelling boom from a station within the aircraft utilising 3D screens.
The drogue stabilises the hose in flight and provides a funnel to aid insertion of the receiver aircraft probe into the hose. The hose is connected to a Hose Drum Unit (HDU) mounted in the aircraft fuselage, and/or on wing-mounted pods, and when not in use the hose is reeled completely into the HDU. The receiver aircraft has a rigid probe protruding or pivoted on a retractable arm on the aircraft's nose or fuselage. The valves in the probe and drogue that are most commonly used are to a NATO standard and were originally developed by FRL. This standardisation allows drogue-equipped tanker aircraft the ability to refuel probe-equipped aircraft from other nations. Generally speaking, the hose and probe method puts the onus on the receiver aircraft to get in position to receive fuel, the tanker aircraft merely getting in position at the correct speed and altitude, and then extending the hose for the receiver. Of note is that this method has a lower fuel- flow rate than high-speed boom equipped aircraft.
We would like to thank the crews and personnel from a number of air arms who have co-operated with Jetwash Aviation Photos over the years, enabling us to obtain the photographs within this article. They are too numerous to mention, but suffice to say we are very grateful for their assistance.
A prototype KC-390 is seen refuelling a pair of FAB AMX aircraft ©Embraer/FAB
As greater numbers of aviation pioneers vied to set new aerial long-distance records using inflight aerial refuelling, one such enthusiast, Sir Alan Cobham, a member of the Royal Flying Corps and a pioneer of long-distance aviation, made flights to places as far afield as Africa and Australia as he began experimenting with the possibilities of in-flight refuelling. In 1934, Cobham founded Flight Refuelling Ltd (FRL) and by 1938 had used the looped-hose system to refuel aircraft as large as the Short Empire flying boat Cambria, using an Armstrong Whitworth AW23.
After WWII ended, the US Air Force purchased a small number of FRL looped-hose units and fitted them to some Boeing B-29 bombers to refuel specially equipped B-29s and later B-50s. The USAF version had an auto-coupling on the refuelling nozzle which allowed high-altitude air-to-air refuelling. This system was used by the B-50 Superfortress Lucky Lady II of the 43rd Bomb Wing to make the
As with Germany, the Canadian government is now looking to replace the ageing A310 aircraft. At present the A330-MRTT seems to be leading the race as a replacement for the Polaris, with the Boeing KC-46 having been rejected as a viable option. However, it is still quite possible that second-hand civilian aircraft may well be purchased and converted due to Canada's budgetary constraints.
Buddy - Buddy Refuelling
A Xian H-6U refuelling a pair of Chengdu J-10 fighters
The KC-10's boom operator controls refuelling operations through a digital, fly-by wire system. Sitting in the rear of the aircraft, the operator (seen in the image below), can see the receiver aircraft through a wide window. During boom refuelling operations, fuel is transferred to the receiver at a
maximum rate of 1,100 gallons (4,180ltrs) per minute; the hose and drogue refuelling maximum rate is 470 gallons (1,786ltrs) per minute. The KC-10 can also be refuelled in-flight by a KC-135 or another KC-10A to increase its range. The KC-10A entered service in 1981 and to date has only seen service with the United States Air Force, although with the type now being withdrawn it may well be that some see future service elsewhere.
Mention the word tanker to most aviation enthusiasts or pilots and they will automatically think of Boeing's KC-135 Stratotanker. A legend within the tanker community, the KC-135 has been around for over 60 years, with the first KC-135A (Boeing model number 717-100A), serial number 55-3118, for the US Air Force, being rolled at Boeing's plant in Renton, Washington, on 20 July 1956.
KC-135R #62-3551 seen left, was built as an A-model before being fitted with the General Electric/SNECMA CFM-56 engines. The aircraft's crew are seen prior to a mission from RAF Mildenhall in July 2011.
The Airbus A400M was launched in May 2003 to respond to the combined needs of seven European Nations (Belgium, France, Germany, Luxembourg, Spain, Turkey and the United Kingdom). The A400M assembly takes place in Spain, with the wings manufactured in the UK, and the fuselage built in Germany. The A400M made its first flight on 11 December 2009, with the first production aircraft delivered to the French Air Force in August 2013.