Aerial Refueling: Nine Decades of Sheer Innovation and Precision

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Aerial Refueling: Nine Decades of Sheer Innovation and Precision



Aerial Refueling is the best thing since sliced bread! Most millennial folks would agree with me on this and for some of you out there who think it is a neologism, do not be alarmed for it isn’t. I assure you, this is going to be as thrilling as you vicariously sky-diving out of a Cessna. But before we dwell deep into the realms of Aerial Refueling, we must first incorporate and inculcate core fundamental aspects of Airport Fueling, Aviation Fuels, and the origin of Aerial Refueling, a concept that is also referred to as Air Refueling, In-Flight Refueling (IFR), Air-to-Air Refueling (AAR) or Tanking. We shall even examine some of the Aircraft used by the Indian Air Force, US Air Force, and the Royal Air Force.

Before writing this article, I had pondered upon what a day in the life of a Fueler at a ground station would be like, let alone develop a perspective on how the scenario would be like mid-flight. And thus, I had stumbled across this intriguing video of Poonai, an Allied Aviation employee who supplies aviation fuel to JetBlue's very own Airbus A380 aircraft. I paid close attention to his immaculate communication with the fuel dispatchers and the pilot and observed how critical protocols (such as Safety protocols, Fuel plans, Inspection procedures, and Record Keeping) were mandatory and imperative to a stable balancing of fuel in the Aircraft’s tanks. The aviation fuel used to carry out the task was the Jet-A Fuel. Jet-A and Jet A-1 fuels are normally used in commercial airliners. Some of the military based fuels used are JP-1, JP-2, and JP-3, etc. These military aviation fuels have higher freezing points that are correlative to the aircraft that fly at higher altitudes. Thus, aviation fuels play a crucial role in the flight efficiency of an aircraft. Fuelers such as Poonai work for approximately 8-14 departures each day depending on the fuel loads carried out and the entire fueling procedure takes about 40 minutes to execute. If you’d like to see the entire procedure, I’d suggest you click on the link below.. immediately!

There are some days that aren't that stressful as a fueler. Take an example below..





What is Aerial Refueling?

After reading the ground procedures of Airport Fueling, ask yourself this, “What would the experience be like mid-flight?”
Back in 1909, a British weekly magazine by the name of Punch had also come up with a humorous illustration (given below) questioning whether Aerial Refueling was a probable feat.

Courtesy: wikipedia.org

It makes you want to giggle as well as contemplate right? Well, we can now address the definition of Aerial Refueling. It is defined as the method of transferring fuel from one aircraft (the tanker) to another aircraft (the receiver). In the backdrop of World War II, many had witnessed the use of Aerial Refueling in order to carry out various missions. Yes, it is pretty fascinating so as to how people had managed to quickly understand the methodology and immediately use it to their benefits in the time of war. And in the exact words of Richard Barke,
 The highest art form of all is a human being in control of himself and his airplane in flight, urging the spirit of a machine to match his own.
The earliest attempts of Aerial Refueling had taken place in the United States of America. On June 27th, 1923, two Airco DH-4B Biplanes of the United States Army Air Service had conducted the world’s first Tanking. Capt. Lowell Herbert Smith and Lt. John P. Richter was one of the first Airmen to complete the In-Flight Refueling operations. On August 27-28, 1923, it was Capt. Lowell Herbert Smith himself who set an endurance record of more than 37 hours of flight with the help of mid-flight refueling. There was a total usage of 2,600 Liters of Aviation Gasoline, 140 Liters of Engine Oil, and with the help of two other D-4B Aircraft Tankers.

Courtesy: wikipedia.org

Operations Carried Out

Generally speaking, in the armed forces, Aircraft to Aircraft refueling is a procedure that is customized to provide an extended range of a tactical aircraft that receives the fuel in order further improve its combat potential. This procedure is sometimes susceptible to various problems mid-flight and thus, situational awareness and strict protocols must be catered to in order to react to contingencies. The two main procedures used in Air-to-Air refueling are Boom and Probe-Drogue

Boom /Flying Boom

This aviation manoeuvre involves a telescopic tube that transfers aviation fuel from the tanker to the receiver's receptacle. This telescopic tube is controlled by the aircrew and the operator who generally goes by the term 'Boom Operator' is responsible for administering the flight control surfaces in order to achieve smooth refueling. The term boom, flying boom, and boom operators is generally used in the United States Air Force. Countries such as India generally use the Probe and Drogue method. Given below is a perfect example of a Flying Boom Aerial Refueling mission that is carried out by Utah Air National Guard member Sargent Major Jason Blood, the Boom Operator on board the KC-135 Stratotanker (a tanker extensively used by the U.S Air Force). The receiving aircraft is the infamous C-17 Globemaster III.





Important Note: Flying Boom refueling operations are carried out on one aircraft at a time but at a faster pace.

A boom operator's Boom Pod  used for Aerial Refueling operations
(courtesy: wikipedia.org)


Probe and Drogue

As the name suggests, this mid-air refueling method uses a probe (a versatile retractable, protruding arm placed on the Aircraft's nose or fuselage) and a drogue (a basket-like structure that resembles a shuttlecock; it is connected to a flexible hose with a narrow valve). The probe is always on the receiving aircraft and the drogue (sometimes operated by a boom operator just like in flying boom or situated inside the wings of an aircraft) on board a tanker aircraft. In order to carry out this operation, the tanker and the receiver must be aerodynamically in sync with each other along with the drogue/hose protruding out of the aircraft based on stable air conditions. The pilot of the receiving aircraft controls the flight in order to establish a connection with the probe and the basket-like structure. In order to vividly explain the concept, we can examine the following probe and drogue mission carried out by the Russian Air Force. The given task is carried out on a fleet of Sukhoi aircraft (Su-24, Su-30, and Su-34) with the assistance of an Ilyushin IL-78 Tanker. The IL-78 Tanker is also utilized by the Indian Air Force as well.



What are the differences between Flying Boom and Probe-Drogue methods of Aerial Refueling?

Compared to Probe and Drogue, Flying Boom method is applied for a larger fuel consumption of an aircraft. But unlike the probe and drogue, flying boom cannot be used on slower moving rotorcrafts as it moves at higher speeds. Also, Probe and Drogue method can be carried out on two different aircraft simultaneously as shown in the figure below.

The Indian Air Force generally refer to this process as MARS (Mid Air Refuelling System). As you can see, we have two Sukhoi MK-30 Aircraft in sync with one another and with the assistance from the IL-78 Tanker.
(Courtesy: wikipedia.org)

More images from around the world
The Sikorsky CH-53E Super Stallion helicopter carrying out a Probe and Drogue operation.
(Courtesy: wikipedia.org)

A retractable refueling boom on board the McDonnell Douglas KC-10 Extender ready for operation,
(Courtesy: wikipedia.org)

The Royal Air Force's very own Victor K2 Tanker, a strategic air bomber is used for various in-flight refueling operations. If you carefully observe the different hoses protruding out of the aircraft, you will notice two of them are smaller compared to the big one. The smaller ones are utilized for smaller aircraft and the bigger belly hose is used to supply fuel to larger aircraft.
(Courtesy: wikipedia.org)


If you'd like to see more exciting videos on Aerial Refueling procedures, click on the links below!

Until then, stay Turbocharged!

Air Refueling procedures between MC-130J Tanker & UH-60 Helicopter

A-10 Thunderbolt II Refueling

B2 Aerial Refueling Procedures

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