“Air Power is like oxygen. When you have enough, you don’t have to think about it. When you don’t have enough, that’s all you can think about” – Gen. Frank Gorenc, USAFE-AF AFRICA Commander.
This quote is very accurate in today’s modern world. Almost every nation on the planet is spending a significant amount of funds in defense. Centuries ago, when continents would no fight with each other, wars were taking place within frontiers; defense was limited only to on ground forces. As humans grew further and exposed to the rest of the world, there arose a need for countries to protect their skies and waters in addition to physical boundaries. Thus the formation of aerospace and navy.
Today, almost every nation has its own air force to protect its skies, for surveillance and trade and transport. Every mode of transport requires fuel, be it on roads, in the waters or skies. It’s easy to refuel vehicles on roads as we have fuel stations situated in almost every city. Ships can also be refueled easily since ships don’t submerge due to fuel inefficiency. But, what if a plane’s fuel gets over mid-air? Can you refuel a plane? And How?
Yes, it is possible!
Air-to-Air Refueling (AAR) helps deliver fuel to aircraft floating mid-air. AAR is also called in-flight air refueling, aerial refueling or tanking. It is a process of transferring aviation fuel from one military aircraft to another during flight. The fuel supplier is called “the tanker,” and the receiving plane is called “the receiver.”
Aerial Refueling History
Military aircraft have used air-to-air refueling for nearly a century.
1921- The wold’s first manual aerial refueling was performed by a man named Wasley May on November 2, 1921. He climbed walked on the wing of Lincoln Standard to climb on Curtiss JN-4 carrying a 5 gallon (19 liters) on his back. It was a successful manual refueling mission.
1923- After one and a half year, the U.S. Air Force, on June 27, 1923, carried out first air refueling using a flapping hose mechanism. The U.S. used two Airco DH-4B biplanes.
1934- Alan Cobham founded a company named (Flight Refueling Limited), which later brought significant changes to the aerial refueling.
1946- All-weather and day-night demonstration flights having distant interceptions that used radar and transponders were flown in association with British South American Airways
1948- The U.S. government purchased two FRL’s aerial refueling hardware.
1951- Closure of the Cold War gave rise to the in-flight refueling system. During the Korean war, the world’s first combat mission using aerial refueling was executed.
Aerial Refueling Today
From such beginnings, aerial refueling has become the main enabling factor of military airpower. In addition to hit targets anywhere in the world, another key feature of air-to-air refueling is that fighter-bombers can take off with heavier loads and far less fuel. This tanking process has helped fighter jets to carry more of ammunition whereas cargo aircraft can lift off with extra extremely heavy loads and refuel while en-route.
Today’s military air forces are very much dependent on aerial refueling, yet commercial aviation never would utilize tanking techniques. A modern aircraft carries a lot of fuel. While a regular pickup truck on the road carries 30 gallons (113 liters) of fuel, an American F-16 carries 880 gallons (3331 liters) of fuel, i.e., equivalent to 30 pickup trucks. An F-22 has a capacity of carrying 2,600 gallons (9842 liters) of fuel.
Aerial Refueling Systems
The industry follows two aerial refueling systems- 1) Probe & Drogue 2) Boom refueling. These systems are operated by a refueling operator sitting in the tanker aircraft, who manages the connection of the probe & drogue or boom refueling with the receiver aircraft.
Probe and Drogue-
In 1939, FRL’s looped hose provided a workable aerial refueling system for large, multiengine airplanes; however, its adaptation to bomber planes in which there was no crew to connect the hose was impossible. Brainstorming onto the idea of doing something woth the hose, FRL soon coined what we today call probe & drogue system.
In this system, initially, a small plane was equipped with a probe that could be attached to a drogue at the end of a refueling tube trailing behind a tanker. At the end of the hose, there is a funnel-shaped drogue, a basket that looks like an oversized shuttlecock. The drogue balances the trailing hose and provides a lead into the connector. The pilot guides the probe into the drogue to make the connection. In April 1949, the first test was carried out using four B-29s and a pair of F-84s.
By using probe & drogue aerial refueling system, a tanker aircraft pumps up to 1500-2000 lb (220-290 gallons) of fuel per minute. During refueling, a tanker and receiver need to maintain 80 feet of distance.
Boom Refueling- Probe & Drogue and was hailed as the system for future since it was simpler, cheaper and weighed less than a Boeing boom. Though it did not require a skilled operator, there were several problems with the system. It used a lot of rubber, which could become unreliable in the -60˚F (-51 Celsius) temperatures above 30,000 ft.
In 1959, the boom’s incompatibility with probe equipped airplanes was solved with a boom-drogue-adapter – a flexible tassel affixed to the end of the boom with a basket at its end to receive a probe. However, when a boom tanker aircraft had an adapter attached, it could not serve receivers fitted with a boom receptacle.
Compared to probe and drogue aerial refueling system, a tanker aircraft using boom refueling system pumps 6000lbs (880 gallons) of fuel per minute. During the refueling process, the distance between a tanker and receiver is around 35 feet.
Aerial Refueling Aircraft Types and Sizes
Currently, the Boeing KC-135 is the standard tanker for the North Atlantic Treaty Organization (NATO) planning. It is a medium-sized tanker with a max gross weight of over 300,000 pounds. Most of the other tankers, including Boeing’s KC-135, will be in the medium to the large category with maximum weights between 350,000 and 500,000 pounds.
Several NATO members are now looking to improve aerial refueling capabilities, while the industry is creating new platforms. More tankers aircraft are being built by member nations – Italy B767, France/Germany/Spain A400M, the U.S. KC130J, and the U.K. A330.
Companies Providing Aerial Refueling
Leading aerial refueling service providers include –
- Cobham Plc. (U.K.)
- Airbus S.E. (Netherlands)
- Parker Hannifin Corp. (U.S.)
- Marshall Aerospace and Defence Group (U.K.)
- Omega Aerial Refueling (U.S.)
- Safran S.A. (France)
- Draken International, Inc (U.S.)
Cobham Plc. shares the legacy of nearly 80 years of experience in the aerial refueling market. It is recognized for the most advanced aerial refueling solutions in the world. While, the U.S. utilizes Boeing’s KC-135 refueling tankers, Cobham Plc. holds the major global market.
Aerial Refueling Market
North America is forecasted to be a rapidly growing market for the air-to-air refueling market. The Military aviation industry in North America is steadily increasing. Thus, more demand has been seen form the American defense sector. Experts say that the aerial refueling market would grow from $539 million in 2019 to $692 million after six years by 2025, at a compound annual growth rate (CAGR) of 4.3%. A rise in the defense expenditure of progressive countries and continuing advancements in technology are major factors driving the growth of aerial refueling market.
1. How does aerial refueling work?
The purpose of aerial refueling is to extend the normal range of an aricraft. Rather than landing on the ground to refuel, a military pilot can arrange a tanker aircraft to refuel along the way. In flying boom method, a boom operator navigates a giant telescoping tube into a receptable located near the front of the receiver plane. After the boom latches in, it sends a signal to the tanker to pump fuel.
2. Do commercial airplanes refuel in the air?
Military aircraft use this process of aerial refueling. Commercial airplanes don’t remain in the air for a longer duration. Most of the commercial airplanes refuel its tanks at airports.
3. Can a helicopter refuel in the air?
Due to its long blades, it’s difficult to refuel a helicopter in the air. Several videos online show how helicopter blades cause a trouble for a drogue to connect with a receiver’s fuel tank opening,
4. How long does it take to refuel a jet in the air?
Because of a tanker’s limitations it may take 3 to 4 minutes for small fighter aircraft. Bigger planes can take 10 times more time to complete the process, and even several tanker aircraft.