100 Years Ago Today, How Was Air Refueling Performed for the First Time and When Did the Turkish Air Force Acquire This Capability?

Celebrating the Centenary of Aerial Refueling

The first aerial refueling in the world took place 100 years ago, on June 27, 1923 in the United States. Aerial refueling is the process of transferring aircraft fuel from one military aircraft (tanker) to another during flight. 

To commemorate this historic day, the US Air Force organized aerial refueling (AFR) flight demonstrations in all 50 states yesterday, June 27. More than 150 tankers, including the KC-135 Stratotanker, KC-10 Extender and KC-46 Pegasus aircraft types, participated in the 100th Anniversary of Aerial Refueling.

"Aerial refueling unlocks the full potential of the American nation's airpower by advancing it through the skies," said Air Mobility Force Commander General Mike Minihan during yesterday's celebratory event. "The AFR capability serves to rapidly deliver airpower to every corner of the globe, combining our strategic vision with operational reality. Aerial refueling has left an indelible mark on aviation history and carries significant weight in our projection of power." He emphasized the importance of the AUM capability as a key force multiplier of American air power.

KC-46 Tanker Aircraft on the left, KC-135R Tanker Aircraft on the right

How was the first aerial refueling accomplished?

On June 27, 1923, American aviators achieved an important first, the first aerial refueling for the first time in history. They accomplished what seemed almost impossible at the time, the first aerial refueling in the skies over the city of San Diego, exactly 20 years after the first airplane flew. On that day, Lieutenant Virgil Hine and Lieutenant Frank W. Seifert, flying a DH-4B, used a hose to transfer gasoline to another DH-4B piloted by Captain Lowell H. Smith and Lieutenant John P. Richter, thus making the first aerial refueling. 

Earlier, on October 5, 1922, Lieutenants John A. Macready and Oakley G. Kelly had set a world endurance record of 35 hours, 18 minutes, 30 seconds over San Diego, California, in their Fokker T-2, earning the Mackay Trophy. Had they not run low on fuel, they might have stayed in the air until personal fatigue or mechanical problems with the T-2 forced them to land.

This experience focused the flight crews on finding a solution to the fuel problem that limited them in the air. Developing a variety of solutions on the ground, flyers at Rockwell Field, San Diego, eventually developed a new system to perform aerial refueling between DH-4B aircraft in the air to eliminate the fuel limitation problem. By testing this system, the flight crews achieved the first successful aerial refueling in history. On June 27, 1923, a hose suspended from a DH-4B carrying Lieutenants Virgil Hine and Frank W. Seifert transferred gasoline to another DH-4B piloted by Lieutenants Lowell H. Smith and John P. Richter.

The next day, on June 28, 1923, a second refueling flight was made in an attempt to break the world record set by Macready and Kelly in the T-2 on October 5, 1922. Unfortunately, a gasoline valve in the receiver aircraft was blocked and the second HYI attempt was unsuccessful. After almost a full day in the air, Smith was forced to make a forced landing on the mud flats near North Island. The plane flipped over during landing and the propeller cracked. The pilot survived.

Two months later, on August 27-28, Smith and Richter made 16 refueling flights, totaling 37 hours and 15 minutes of endurance flying. During this flight, they set 16 new world records for distance, speed and duration. On October 25, 1923, Smith and Richter set a new world record by flying non-stop from Canada to the Mexican border, a distance of 1,250 miles, refueling three times in the air. 

This record also meant proving the theory that refueling in the air would extend the range of an airplane. This paved the way for a whole new range of aerial refueling applications that have continued to this day, even to the point where unmanned aerial vehicles have begun to serve as tanker aircraft.

Aerial Refueling Methods Today

Thanks to this important step in the air, together with other pioneering developments in the field of HMD in the following years, the world's military aviators now have the capability to fly at ranges long enough to circumnavigate the globe, almost without ever touching the ground, and to stay aloft for long periods of time. Thus, every air force, including the Turkish Air Force, with this capability has gained global force reach.

In particular, the aim of the HYI is to enable a fighter aircraft to stay in the air longer, to carry more ammunition loads, and to fulfill the requirements of all kinds of operational missions without time constraints. Air refueling is an important force multiplier for a country that possesses the capability to conduct air refueling. In military aviation, the aerial refueling system has been used by a small number of Air Forces. The AAM aircraft that refuel fighter aircraft are often referred to as tanker aircraft. 

When refueling by tanker aircraft, one of two methods is used, depending on the refueling system of the fighter and/or tanker. Some military transport or AWACS aircraft may also refuel in the air from tanker aircraft.

Flying Boom System: 

In this system, the tail of the tanker aircraft is equipped with a rigid, telescopic arm-like boom (which can be lengthened, shortened and controlled by the operator on board the tanker aircraft). Under the control of the boom operator, refueling is performed by contacting the boom with the refueling slot in the compartment behind the cockpit in fighter aircraft. Aircraft using the Flying Boom method include the F-35A, F-22, F-15, F-16, F-4, B-52 and C-5 Galaxy.

Probe-and-drogue or Hose-and-drogue (Basket) System:

In this method, the protruding horn or thin tube-shaped protrusion, which is usually located on the nose of the fighter jet, is refueled by contacting the basket at the end of the flying hose, which is also under the control of the boom operator, suspended from the tanker wing. This basket-shaped container is also called a windbreaker. The windsock at the end of the hose serves to stabilize the hose in the air. The pilot of the fighter brings his aircraft close to this windsock. He inserts the refueling probe into the funnel inside the windsock to refuel the aircraft. The Hose-and-Drogue system is difficult to use, especially in windy weather. It is a less preferred system than the fying boom system. If the hose moves too much, the fighter pilot may have difficulty in maintaining contact between the wind basket and the refueling probe. Some aircraft that use the basket method are: F-35B/C, F/A-18, Jas-39, Eurofighter Typhoon, Dassault Rafale, Su-30, Su-35, Mig-29 and some helicopters.

Turkish Air Force's Acquisition of Airborne Refueling Capability

The Turkish Air Force uses the KC-135 Stratotanker aircraft for HMD missions. The KC-135 is a tanker aircraft based on the Boeing 707, a civilian passenger aircraft. The Turkish Air Force received 7 KC-135A, which were purchased from the USA through a grant, after the KC-135R modernization. These tanker aircraft were produced between 1959-1963 and delivered to the US Air Force in the KC-135A configuration. In 1993, Turkey requested 7 KC-135A aircraft, which were decided to be decommissioned by the US and stored in the 309th Aviation Maintenance and Refurbishment Group (AMARG). As a result of bilateral negotiations, it was agreed that the aircraft, which would be donated, would be modernized by the US before being delivered to Turkey.

The total cost of this modernization to Turkey was 300 million USD. Upgraded to the KC-135R level, the acquisition resulted in CFM56 engine modifications, enabling the aircraft to comply with lower fuel consumption, reduced air pollution and low noise requirements. 

101st Aerial Refueling Squadron Command (Asena, female wolf) is a squadron under the 10th Tanker Base Command based in Incirlik, which performs aerial refueling missions of the Turkish Air Force Command with its 7 KC-135R aircraft. The squadron became operational on July 24, 1995 with two KC-135R aircraft leased from the United States and started to refuel Turkish fighter aircraft (F-16 and F-4) in the air. Subsequently, in 1997-1998, seven KC-135R aircraft were delivered from the United States, and the Turkish Air Force was able to carry out HLR missions with its own tanker aircraft. With the arrival of the tanker aircraft delivered between December 1997 and July 1998, two tanker aircraft leased from the USA were returned.

In the early 2000s, the navigation and radio systems of Turkish KC-135R aircraft were modified. Pacer CRAG (Compass, Radar and GPS) modernization was carried out in order to increase the navigation capabilities of the aircraft and to maintain a common configuration with the US. With this project, a cockpit avionics upgrade set consisting of a color weather radar display, Enhanced Traffic Collision Avoidance System, Enhanced Ground Prediction Warning System, GPS-assisted Navigation System, Multifunction Display, FMS-800 Flight Control System, Cockpit Voice Recorder (CVR) and Flight Data Recorder was introduced to the aircraft. The first Pacer CRAG aircraft was delivered to the fleet on September 18, 2000.

In the early 2010s, KC-135R Aircraft underwent a second modernization. The aircraft were modernized with Global Air Traffic Management (GATM) System avionics. The first KC-135R aircraft modernized within this framework was received by the Turkish Air Force in April 2011.

In the early 2020s, tanker aircraft underwent a third modernization. Similar to the US aircraft, they were also subjected to the Pacer CRAG 45.1 structural and avionic modernization program. With this modernization, the service life of the KC-135R aircraft in the inventory, which were upgraded to the Block 45 configuration, was extended by 15 years, guaranteeing that the aircraft will remain in service until at least 2036. The first Pacer CRAG 45.1 aircraft was delivered on September 5, 2021.

101st HYI Squadron Command uses Asena as its emblem. Asena is a reference to Asena, a she-wolf in Turkish mythology, who is believed to have nursed and raised an orphaned child from whom Turks are said to have descended. Thanks to the Asenas, the fighter aircraft used by the Turkish Air Force have been able to operate in longer operational radii, stay in the air for longer periods of time, and increase their operational effectiveness in mission types such as patrol, intercept, and air defense. 

The maximum take-off weight of the KC-135R aircraft is 146,283 kg. The maximum fuel load that can be given in HYI missions is 90,718 kg. One KC-135R tanker aircraft can air refuel up to 20 F-16 aircraft at five-minute intervals. The maximum cargo capability of the tanker aircraft, which can also be used in transportation/cargo transport missions, is 37,648 kg of material and 37 passengers.

Conclusion

The first aerial refueling in the world was carried out 100 years ago. Founded in 1911, the Turkish Air Force gained this capability, which is considered an important force multiplier, with the KC-135R aircraft it added to its inventory in 1995. Thanks to this capability, Turkish fighter aircraft, and later AWACS (Peace Eagle) aircraft, were able to stay in the air longer and reach greater distances (increased range and operational radius).

The Turkish Air Force plans to replace the tanker aircraft in its inventory with the new generation A330 Multi-Role Tanker and Transport (MRTT) Airbus Defence & Space (ADS) aircraft in the coming years, in order to maintain the benefits of having the capability to operate in the HMD. With the participation in the A330 MRTT Project, it is likely that the new tanker aircraft will be delivered to the 101st HYI Squadron Command by the early 2030s. If these aircraft are acquired, it will also be possible to obtain air-to-air automatic refueling capability. On the other hand, UAVs, which are also produced as Tanker UAVs, have started to be used today. In this context, Turkey may consider producing its own Tanker UAVs or procuring Tanker UAVs similar to the Boeing MQ-25 Stingray from countries such as the US. 

The field of tanker UAVs, which can only refuel 2-3 combat aircraft in the air under current conditions, is expected to make great progress in the coming years. The MQ-25 Tanker UAV made its maiden flight in September 2019, and in June 2021, the MQ-25 Tanker UAV successfully carried out its first HMD mission by refueling F/A-18 Super Hornet fighter jets. The next refueling test was conducted with the F-35C. The U.S. Navy is planning to acquire 72 MQ-25 tanker UAVs.

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