SP Guide Publications puts forth a well compiled articulation of issues, pursuits and accomplishments of the Indian Army, over the years

— General Manoj Pande, Indian Army Chief

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— Admiral R. Hari Kumar, Indian Navy Chief

My compliments to SP Guide Publications for informative and credible reportage on contemporary aerospace issues over the past six decades.

— Air Chief Marshal V.R. Chaudhari, Indian Air Force Chief

First Aerial Refuelling with a Drone Tanker

On June 4, 2021, the US Navy conducted its first ever aerial refuelling of an F/A-18E-F Super Hornet, a manned aircraft of the US Navy, by an unmanned flight refuelling aircraft (FRA), an MQ-25 Stingray test vehicle. Designed, developed and manufactured by Boeing, this was its first midair tanking mission. The successful test was carried out with the MQ-25 T1 test asset employing the Cobham Aerial Refuelling Store that is used by F/A-18s to perform refuelling operations. “This flight lays the foundation for integration into the carrier environment, allowing for greater capability towards manned-unmanned teaming concepts,” said Rear Admiral Brian Corey who oversees the Programme Executive Office for Unmanned Aviation and Strike Weapons”.

Issue: 06-2021By Air Marshal B.K. Pandey (Retd)Photo(s): By Boeing


The history of the development of the capability of refuelling an aircraft during flight, dates back to 1912 when the first attempt was made using a method that was rather primitive as it involved passing of a can of aviation fuel manually from one airplane to another while in flight. Over a decade later, this method was replaced by another in which fuel was transferred from the wing tanks of one aircraft to the wing tanks of another and was described as wing-to-wing transfer. In this method of aerial refuelling, a fuel hose pipe was dangled from the wing tank of the refueller aircraft and one member of the crew of the recipient aircraft, was required to grab the end of the hose pipe and refuel the recipient aircraft. As fuel pumps were yet to be developed, fuel from the wing tank of the aircraft on top was transferred to the aircraft flying below it by making use of the force of gravity. The first such refuelling exercise was carried out on June 27, 1923, nearly 100 years ago, between two Airco DH-4B biplanes by the pilots of the United States (US) Army Air Service.

A flying endurance record was set in August 1923 by three Airco DH-4B aircraft of the US Army Air Service consisting of two aerial tanker aircraft and one receiver aircraft in which the receiver aircraft remained airborne for more than 37 hours during which mid-air refuelling was carried out nine times to transfer a total of 2,600 litres of aviation fuel and 140 litres of engine oil. Similar aerial refuelling trials were carried out in that period by the Royal Air Force of the United Kingdom as also by the French Air Force; but not with the same level of success as achieved in the US. Over the years, with aerial refuelling being taken up with the Air Forces of several nations, two main aerial refulling systems were developed. These were the “Probe and Drogue System” and the Flying Boom. The Probe and Drogue System proved to be simpler to adapt to existing aircraft, but the Flying Boom provides a much faster rate of transfer of fuel. However, it requires a dedicated boom operator station in the refueller aircraft.

The capability of being able to receive fuel while in flight allows the receiving aircraft to remain airborne for a longer period of time as well as enhance significantly its operational range as it can top up its fuel tanks well after getting airborne. An aircraft on an operational mission that has the capability to receive fuel in flight, can get airborne with much higher payload which could be by way of weapon load, cargo or personnel. This is particularly relevant if the aircraft is required to operate from an airfield located at high altitude which severely limits its all up weight for takeoff. If the aircraft is on a strike mission deep inside enemy territory, the capability of receiving fuel in flight will not only enhance its strike range, it will also facilitate launching of strike on multiple targets as well as give the aircraft more loiter time.

The first time that aerial refuelling was used by aircraft that were engaged in actual combat was by the South Korean Air Force during the war with North Korea in the early 1950s. These missions that were carried the out by the F-84 fighterbomber aircraft of the South Korean Air Force with aerial refuelling, were undertaken from airfields in Japan as their own air bases located in South Korea had been overrun by the North Korean forces with the support from China. The South Korean Air Force had converted B-29 bombers that were fitted with the drogue-and-probe in-flight refuelling system. The probe was fitted on one of the wing-tip fuel tanks of the F-84 combat aircraft.

The MQ-25 T1 is the predecessor to the four engineering development model MQ-25 aircraft under production, the first of which is expected to be delivered for operational deployment later this year. The US Navy is planning to procure over 70 MQ-25 T1 aircraft, which will replace the F/A-18E Super Hornets that are currently being employed in the aerial refuelling role. This will allow the aircraft carrier fleet of the US Navy to have significantly higher numbers of F/A-18E Super Hornets available for operational missions instead of these being reserved only for aerial refuelling missions. The aerial refuelling exercise carried out using the MQ-25 Stingray test vehicle on June 04 this year, will certainly prove to be a quantum leap in developing the capability of aerial refuelling for combat platforms.