Aerial refueling, also referred to as air refueling, in-flight refueling (IFR), air-to-air refueling (AAR), and tanking, is the process of transferring aviation fuel from one military aircraft (the tanker) to another (the receiver) during flight. The procedure allows the receiving aircraft to remain airborne longer, extending its range or loiter time on station. A series of air refuelings can give range limited only by crew fatigue and engineering factors such as engine oil consumption.
Aerial refueling has also been considered as a means to reduce fuel consumption on long-distance flights greater than 3,000 nautical miles (5,600 km; 3,500 mi). Air-to-air refueling (AAR), can also improving economic efficiency of air transport services through the use for regional aircraft technology of which can provide the exploitation of these aircraft on long-haul non-stop flights instead of expensive long-haul aircraft. Potential fuel savings in the range of 35-40% have been estimated for long haul flights (including the fuel used during the tanker missions).
Air-to-air refuelling (AAR) stands as one of the key force multiplier which allows projecting military power far beyond their national boundaries. Because the receiver aircraft can be topped up with extra fuel in the air, air refueling can allow a takeoff with a greater payload which could be weapons, cargo, or personnel: the maximum takeoff weight is maintained by carrying less fuel and topping up once airborne. Alternatively, a shorter take-off roll can be achieved because take-off can be at a lighter weight before refueling once airborne.
For today’s short combat radius platforms in particular, the growing frequency of sorties flown at ever-longer distances away from carriers or ground bases has increasingly made refuelling an essential mission component. The requirement for AAR is likely to increase in the future as there is a greater requirement for persistence. ISR and C2 assets, for example, are increasingly likely to demand AAR services to enhance situational awareness. The Falklands conflict of 1982 highlighted the necessity for air-to-air refuelling, particularly for the successful prosecution of an air war at long range.
Of all air-power force-multipliers, Air-to-Air Refuelling (AAR) is amongst the most significant. It provides an essential capability that increases the range, endurance, payload and flexibility of all capable receiver aircraft, and is especially important when forward basing is limited or unavailable, or air base operations limitations impose constraints, according to JAPCC, ‘Air-to-Air Refuelling Consolidation: An Update’, March 2014. “To support overseas deployments anywhere in the world at short notice AAR is only becoming more important,” says James Kemmitt, product management director at Cobham Mission Systems – one of the world’s leading refuelling technology suppliers.
Airbus has conducted the first-ever fully automatic air-to-air refuelling (A3R) operation with a boom system in 2020. Conducted over the Atlantic Ocean, the flight test campaign involving an Airbus tanker test aircraft equipped with the A3R solution. An F-16 fighter aircraft of the Portuguese Air Force was used as a receiver. The operation marks a significant milestone of the industrialisation phase of A3R systems prior to its implementation in the A330 MRTT tanker development. The test lasted for a total of 45 flight test hours, with 120 dry contacts with the A3R system. It covered the whole aerial refuelling envelope, consolidating the capabilities of the development of F-16 and MRTT at this stage.
Following the system activation by the ARO, the A3R flies the boom automatically. With an accuracy of a few centimetres, it maintains the alignment between the boom tip and the receiver receptacle. Real-time alignment and stability check are done to ensure a safe distance is maintained between the boom and the receiver. This also determines the optimum moment to extend the telescopic beam, achieving connection with the receiver. Following this, the transfer of fuel is initiated. Upon completion, the disconnection is commanded. This clears the boom away from the receiver by retracting the telescopic beam. The boom flies away, keeping a safe separation distance. During the operation, the whole process is monitored by ARO. No additional equipment on the receiver aircraft is required for the transfer of fuel by the A3R system. The system will reduce air refuelling operator (ARO) workload, improve safety and optimise the rate of air-to-air refuelling transfer in operational conditions. Additionally, it will maximise aerial superiority.
The future trends to meet the increasingly challenging demands of today include, “These include a wider operating envelope – airspeed, range and altitude – suitability for harsher environments, autonomous operation, lower life cycle costs, increased safety and reliability and reduced maintenance, roll on/roll off capability and compliance to new more stringent airworthiness regulations.”
Aerial refuelling aircrafts
The US Air Force’s (USAF) KC-46A Pegasus military aerial refuelling aircraft is under flight tests from Edwards Air Force Base (AFB) to demonstrate its capability as a receiver aircraft. Though the Pegasus aircraft is used to refuel other jets, it also needs to be refuelled by KC-10 Extenders or KC-135 Stratotankers in order to extend its range.
Boeing KC-46 Pegasus is among the most advanced military aerial refuelling and strategic transport aircraft in operation. Developed by Boeing from its 767 jet airliner, the wide-body, multirole tanker can refuel all US, allied and coalition military aircraft, and is also designed to carry passengers, cargo and medical patients. The Pegasus can also detect, avoid, defeat and survive threats using multiple layers of protection.
The development of the aerial tanker variant of China’s domestically developed Y-20 large cargo plane is apparently entering the final stages, as a recent photo captured what seems to be a Y-20 tanker variant conducting aerial refueling for a J-20 stealth fighter jet, media reports said. Judging from the photo, the Y-20 aerial tanker was using a hose-and-drogue refueling system, while the J-20 was using a fuel-receiving probe, Fu Qianshao, a Chinese military aviation expert, told the Global Times. Now that the Y-20 tanker has made it to the sky and tested its capabilities with the J-20, this type of aerial tanker variant is likely technically mature and can enter test service, Fu said.
In February 2020, Teng Hui, commander of an Air Force aviation regiment of the PLA Western Theater Command and Y-20 pilot, said on China Central Television that “The Y-20 cargo plane has variants like the Y-20 aerial tanker and Y-20 aerial early warning aircraft. I believe that people will see our Y-20 aerial tanker debut on the battlefield in the not too distant future.” It is widely expected that the tanker variant of the Y-20 will work together with and eventually replace the PLA’s very few imported Il-78 tankers and the domestically developed but less capable HU-6.
Combinations of the Y-20 aerial tanker with the likes of the J-20 fighter jet and H-6N strategic bomber can significantly expand the operational range of the Chinese People’s Liberation Army (PLA) Air Force and defend China against military aggression from West Pacific, analysts said in Nov2020. Upon receiving aerial refueling from the Y-20 aerial tanker, the J-20 can extend its range to more than 8,000 kilometers and combat radius to more than 3,000 kilometers, Ordnance Industry Science Technology magazine said, noting that with several refuels, the J-20 can travel more than 10,000 kilometers for intercontinental flights.
India joined elite group of countries having air-to-air refuelling system for military planes, in Sep 2018, when the first ever mid-air refuelling of Tejas combat aircraft took place. The milestone was achieved at 9.30 am when 1,900 kg of fuel was transferred from the Russian-built IL-78 MKI tmid-air refuelling tanker of IAF to the Tejas LSP8 at an altitude of 20,000 feet, said a release from HAL, which has developed the light combat aircraft (LCA). Successful ‘dry’ docking of aerial refuelling probe with the mother tanker was carried out on September 4 and 6, he said. HAL officials said in the dry docking no fuel was transferred.
The new standard A330 MRTT from Airbus has improved tanker performance and operational efficiency promising a fuel-burn reduction of up to 1%. In addition to the structural and aerodynamic modifications which help achieve the increased fuel efficiency, the new standard A330 MRTT also features upgraded avionics computers and enhanced military systems.
It is capable of carrying a maximum payload of 245,000 lb (111,000 kg) of fuel, an additional 99,000 lb (45,000 kg) in non-fuel payload and 291 passengers. The growing number A330 MRTT operators, including Australia, the United Arab Emirates, Saudi Arabia, Singapore, South Korea, France, Spain and RAF.
In operations against ISIS over Syria and Iraq a single KC-30A proved capable of tanking a wide variety coalition of assets. These included F/A-18F Super Hornets, other KC-30As (Australian MRTTs are equipped with the UARRSI), E-7A Wedgetails, C-17 Globemaster IIIs, AV-8B Harriers, Eurofighter Typhoons and Dassault Rafales. The flexibility of the KC-30A was demonstrated when in November 2015 a Boeing E-7A Wedgetail Airborne Early Warning and Control (AEW&C) aircraft performed its longest mission over Iraq lasting 17 hours and 6 minutes requiring two aerial refuellings.
Two approaches are currently used for aerial refuelling: the flying boom, where a retractable boom is extended to be connected to the fuel receptacle of the aircraft to be refueled; and the probe and drogue method, where a flexible hose with a drogue attached to its end is extended and the receiver aircraft maneuvers to insert the probe into the drogue.
The US Air Force uses a flying boom system, where a long, thin tube extends from the tanker into a receptacle on the receiving aircraft. The boom is what will run the fuel from the tanker to the receiver. Jets like the F-22 and F-35 have boom receptacles for receiving the fuel from the boom.
To begin, the pilots consider what they call altitude block, which are like little roads in the sky, permanently laid out at different altitudes all over the US The pilots agree on a starting point, an end point, and a meetup time. The tanker generally arrives about 15 minutes before the receiver, who will arrive about 1,000 feet lower than the tanker.
And they’re flying what we call a racetrack pattern, where they’re just flying in a circle, waiting for the receiver to show up. Both the tanker and the receiver will continue down the track. They’re a mile behind the tanker, a thousand feet below, and then they usually start to close in. They decrease that altitude separation until they get to the astern position, which is about 50 feet behind the aircraft, at which point the boom operator, they are directing the receiver at that point to close in for the contact.
That’s when the boom operator will take over and will tell them come in, go out, go faster, go slower, up or down, until they’re in the sweet spot, and then that boom operator can make the contact with that boom. The boom operator has full control over the boom, and can extend and retract it as needed. The operator can disconnect the boom when fueling is complete, but if the receiving plane moves off track, the system triggers an automatic disconnect. This is very helpful, because inclement weather, turbulence, unexpected turns, and air traffic can all make it difficult to stay connected.
A slightly easier aerial refueling method is the drogue probe, used on almost all of the Navy and Marine fighter jets. A drogue fire hose with a parachute on the end comes out of the tanker, while the receiver extends a thin probe into the parachute, like a bullseye. The probe-and-drogue, is simpler to adapt to existing aircraft, and the flying boom, which offers faster fuel transfer, but requires a dedicated boom operator station.
In the literature, there have been a variety of computer vision solutions for the aerial refuelling problem. In one technology, the drogue position is estimated using an infrared camera placed in the receiver aircraft and infrared leds placed on the drogue structure. The pose of the drogue is estimated matching the 2D position of the leds with their known 3D positions in the drogue. Synthetic images are used to test the algorithm. On the other hand, a set of beacons mounted on known positions in the drogue are used in. These beacons are detected by a VisNav sensor placed in the receiver aircraft. A communication link between the sensor and the beacons allows the receiver aircraft to triangulate the pose of the drogue with update rates of 100 Hz.
For the flying boom refuelling method, a vision system based on deformable contour algorithms was proposed in to obtain relative 3D position estimations. A camera was placed on the tanker aircraft looking down towards the receiver aircraft, capturing images of a passive target painted near the refuelling receptacle. The HSV (hue, saturation, and value) color space was used to increase the robustness under variations in lighting conditions.
Synthetic images were used in this case to test the performance of the algorithm. On the other hand, in, the performance of well-known corner detectors (SUSAN and Harris) are analyzed for the docking maneuver involved in the flying boom method. A camera is placed in the receiver aircraft looking upwards, capturing the tanker aircraft. The feature extractor algorithms detect corners of the tanker aircraft, which are matched with a set of known physical features of the tanker. The positions of the matched corners (2D-3D match) are used to evaluate the relative position and orientation of the aircrafts.
Software company Pivotal, backed by Dell EMC, VMWare, GE, Microsoft and Ford, has developed a tanker refuelling solution for the USAF with the US Defense Innovation Unit Experimental (DIUx); Running on the firm’s Pivotal Cloud Foundry platform, the software solution was built for under $2m in 90 days and is now being used in operational areas including Qatar. It currently saves the US Air Force $1 million per day in fuel costs, with the software being managed by just one person.
Specific to the air environment, the proliferation of advanced air- and ballistic defence capabilities; man-portable air-defence systems (MANPADS), are also increasingly available to insurgent groups. These threats make life difficult for the crews who fly the tanker aircraft.
Writing in a Brookings Institution Policy Paper back in 2014, US Navy Commander Gregory D. Knepper warned that the vast ranges predicted for future operations in contested airspaces risked turning AAR into a new strategic vulnerability and making airborne tankers into prized targets.
Adding ISR capabilities to tanker aircraft
Looking beyond their main purpose, Kemmitt believes that to be effective in the coming conflicts, assets will need to be multi-functional and he sees tomorrow’s tankers doubling-up as flying sensor suites and data relay hubs in an increasingly networked battlespace.
Adding such intelligence, surveillance and reconnaissance (ISR) capabilities is another area that Airbus has already started to explore. The spokesman says that the company has been looking at bringing the likes of signals intelligence or airborne ground surveillance to the A330 MRTT platform, to allow it to perform simultaneous ISR tasks during a single mission, without affecting the aircraft’s primary role. Additional communication systems for the aircraft are also under consideration, as well as equipping it with appropriate sensors and a mission system.
Defensive Aid Suites
Defensive aid suites will therefore be increasingly important for military support platforms, while stealth is fast becoming a pre-requisite for air forces wishing to maintain freedom of action in a high-threat environment. To maximise value for money and provides operational flexibility, new AAR platforms provide multi-mission services that can support combat air, ISR, airborne command-and control (C2) and maritime-patrol missions. The JAPCC paper also recognises the trend towards multi-mission aircraft and notes that tanker transport aircraft may in addition be used for aero-medical and ISR tasks.
European AT/AAR assets are already multi-role platforms typically employed in a transport role during peacetime and as an AAR platform during crises. Further capabilities might be squeezed from AT/AAR platforms by adding ISR sensors to provide additional intelligence while the platforms loiter above the battlespace. However, this must not compromise operational effectiveness. Additional functions always come at a cost, and no aircraft can be in two places at once.As Kemmitt explains, “future tankers will potentially need to provide in-theatre support to the receiver aircraft, meaning that they will have to be stealthy to avoid detection as well as having comprehensive defensive aids.”
It could, it seems, see a major step-change in approach, perhaps even moving away entirely from the established commercially derived aircraft that form the mainstay of AAR today, towards the likes of a flying wing design. Incorporating low-observable features and a disguised radar signature would then enable it to follow state-of-the-art stealthy fighters safely far into the anti-access, area-denial battlespaces of tomorrow, with high levels of automation bringing enhanced mission capabilities too.
Automated refuelling technology
Automated aerial refueling (AAR) refers to methods for autonomous refueling of manned and unmanned aircraft.
An Air Force Research Laboratory program was started in 2004 at the AFRL Air Vehicles Directorate. The initial program was the evaluation of technologies that could be used for AAR. The key new concept is the use of precision GPS. The AAR program has since held several flight tests. The important factors were the software and communication systems that kept the aircraft at the proper altitude and speed.
In 2007, the Defense Advanced Research Projects Agency (DARPA), with the help of NASA, demonstrated automatic refuelling from a conventional tanker by a high-performance aircraft. A pilot was on board to supervise, so the demonstration was not entirely automated. It served as the basis for DARPA’s Autonomous High-Altitude Refueling program which, in 2012, demonstrated the potential for fully autonomous aerial refueling of unmanned air vehicles. The final test involved modified RQ-4 drones flying in close formation less than 100 ft from a tanker, close enough for refueling to take place
During aerial refuelling manoeuvres the tanker and receiver aircraft need to fly very close to each other and this close proximity induces a very significant aerodynamic interaction between them. Flying fast-moving aircraft together in the close proximity required for refuelling, and not infrequently in a turn to ensure the tanker can hold on station, is always a potentially dangerous undertaking.
To help reduce the associated risk while also minimising contact time, improving operational efficiency and reducing operator workload, Airbus has begun flight trials of automatic refuelling technology. Aimed to enable the automation of AAR boom contacts, it requires no additional equipment in the receiver aircraft and uses imaging technology to detect the position of the receiver and its receptacle.
“The receiver approach to the tanker is performed manually, as is the initial tracking of the receiver by the boomer,” the Airbus spokesman explains. “The imaging system acquires the receiver and the receptacle position, and the boomer can then accept the system aid while manually extending the telescopic part of the boom and making and maintaining contact.”
He says that proximity trials have already been conducted, and contact trials are planned for the near future.
Future Air Refuelling by the drones
The U.S. Navy plans to finalize its MQ-25 drone program sometime between 2018 and 2019. The Navy’s mission is to craft drones that can be flown off of aircraft carriers and refuel other aircraft mid-flight. Crucial to the success for MQ-25 operations is the integration of the Unmanned Carrier Aviation Mission Control System, or UMCS, within the Navy’s communications infrastructure. Its mechanics are based on its intersection with other Navy assets, specifically the Common Control System, or CCS, software architecture under the Strike Planning and Execution Systems office of Navel Air Systems Command.
The Government Accountability Office plans to spend upward of $2 billion for both the MQ-25 system and other potential unmanned fueling drone systems. Northop Grumman, General Atomics, Boeing and Lockheed Martin have all been awarded contracts for the MQ-25 system. While it would clearly be wrong to suggest that the days of crewed flights are over, things are undoubtedly changing and as Kemmitt points out, “the proliferation of drones will mean that their refuelling will become commonplace like refuelling of manned aircraft is today”. With the dawn of the MQ-25 Stingray and the growing strategic vulnerability of crewed tankers in contested airspaces, perhaps UAVs doing the actual refuelling will gradually become more commonplace too.
Aviation Refueler Market
Aviation refuelers are intended for safe and efficient airliner refilling at any location, relocating fuel into aircraft through metering systems, filter and pump. Its proven strategies integrate novelty combined with industry standard compliance and components to international standards. The modular borders or frames are steel welded arrangements which are hot-dip electrified before pumping gear, filters and meters are fitted. All components and schemes are intended to exploit machineries and heaviness surrounded by the space given to ease prefabrication and tranquil transmission of the pumping gear or module to alternative truck if essential.
Constant escalation in aviation sector coupled with affordable flight availability in emerging economies; owing to new market player entrants are driving the market growth majorly. Increasing number of flights everyday is raising the fuel requirement which eventually is augmenting the aviation refueler market. Thus, for smooth operational activities of flight in the forecast period, the need for aviation refueler is expected to escalate the market growth.
The market can be bifurcated on the basis of product, end user and geography. By product, aviation refueler market can be segmented into 1,000 gallon, 3,000 gallon, 5,000 gallon, 7,000 gallon and 10,000 gallon. By end user, aviation refueler market can be segmented into civil aircraft and military aircraft. On the basis of geography, the aviation refueler market can be segmented into North America, Latin America, Europe, Middle East & Africa (MEA) and Asia-Pacific.
Market By Product: 1,000 Gallon, 3,000 Gallon, 5,000 Gallon, 7,000 Gallon, and 10,000 Gallon
Market By End User: Civil Aircraft, Military Aircraft,
Market By Geography: North America: U.S., Canada, Mexico, Europe: UK, France, Germany, Rest of Europe, Asia-Pacific: China, Japan,
India, Australia, Rest of Asia-Pacific, Latin America: Brazil, Rest of LATAM, Middle East and Africa (MEA): South Africa, Saudi Arabia, and
Rest of MEA
Significant players or competitors taking part in the worldwide Aviation Refueler market are: Esterer GmbH, SkyMark, Garsite, HP Products, Aviationpros, Rampmaster, Refuel International, Westmor Industries, CSPT, JungWoo Tank, Etsy, and Rampmaster
References and Resources also include: