An airplane that refuels airplanes and helicopters in flight. Most of them are converted from large transport planes or strategic bombers. Its function can make the receiver extend the voyage, prolong the endurance and increase the payload, thus improving the combat capability of aviation. The refueling equipment of aerial tanker is mostly installed at the tail of the fuselage, and a few are installed in the engine room under the wing, which is controlled by the pilot or oiler. There are two kinds of refueling equipment: plug cone sleeve type and telescopic tube type. The aerial refueling technology appeared in 1923.

Working principle:

An aerial tanker is an airplane that refuels airplanes and helicopters in flight. Most of them are converted from large transport planes and strategic bombers, and a few are converted into the same type of "partner" tankers by adding refueling systems to fighters. The aerial refueling system includes the refueling device of aerial tanker and the receiving device of oil receiver.

There are two kinds of refueling devices: refueling platform and refueling pod. The "refueling platform" is usually installed at the tail of the fuselage, and the "refueling pod" is usually suspended under the wing. Operated by a driver or oiler. The oil storage tank is assembled on the fuselage and the wing respectively. The oil receiver installed on the oil receiver usually consists of the oil receiver (that is, the probe extending from the oil receiver), the conduit and the anti-overflow self-sealing device. The oil inlet of the oil receiver is an oil inlet check valve. The oil inlet check valve is opened by a servo mechanism or by the interaction between a locating pin fixed on the oil receiver and a stop device. After the oil receiver is inserted into the oil receiver released by the tanker, it is sealed with a leather cup, a liquid seal or an inflatable seal. In addition, other pipelines are shared with the ground pressure refueling system.

Classification of refueling methods:

There are two ways to refuel in the air: hose refueling and hard pipe refueling.

Hose refueling system:

Hose refueling system is mainly composed of tubing reel device, pressure supply mechanism and electronic control indicating device. A telescopic hose of 16 ~ 30m is installed on the tanker. There is an umbrella-shaped conical sleeve at the end of the hose, and there is a refueling joint in the sleeve. A telescopic elbow probe oil receiver is installed on the nose of the oil receiving aircraft. When refueling, the tanker flies above the front end of the oil receiver, and the pilot or oiler opens the locking mechanism of the oil hose reel and stretches out the conical sleeve, which is unfolded under the action of airflow to pull out the oil hose. At the same time, the pilot of the receiver adjusts the flight speed, heading and altitude. When the receiving pipe is inserted into the taper sleeve, the oil circuit is automatically connected and refueling begins. The hose oiling device is simple in structure and easy to install and disassemble. Each equipment can transport 1600 liters of oil per minute, and a tanker can hold several units and refuel several planes at the same time. Pod hose refueling system can also be carried by fighter or attack aircraft to implement "partner refueling" for similar aircraft. However, when the hose is refueled, due to the influence of airflow, the hose will drift and the oil transportation efficiency will be low. It is generally suitable for refueling fighters with high maneuverability and less fuel consumption.

Hard tube refueling system;

The hard tube refueling system is mainly composed of telescopic tube, pressure refueling mechanism and electronic control indication and monitoring device. The telescopic pipe comprises a main pipe and a sleeve, and the outer wall of the main pipe is provided with a lifting rope and a stabilizing rudder. Telescopic tube refueling equipment is generally installed under the tail of refueling fuselage. When refueling, the tanker lowers the telescopic tube through the lifting rope, and the stabilizer stabilizes the telescopic tube vertically and horizontally in a certain spatial range under the action of air flow, and the sleeve extends from the main pipe. At the same time, the oil receiver completed the docking with the tanker and began to refuel. Because the oil pipeline is hard, stable and easy to connect with the oil receiver, the oil transportation efficiency is relatively high, and the maximum oil transportation capacity is 6500 liters per minute. However, its manufacturing process is complicated, and only one receiver can refuel at the same time. Generally, only large tankers can be equipped with this equipment (such as KC- 10, KC- 135).

At present, only the United States has mastered the manufacturing technology of hard pipe refueling, and the fighters equipped by the US Air Force also use hard pipe refueling. Due to the limited deck area of the aircraft carrier, the tankers equipped by the US Navy are all developed from the tactical aircraft used by the aircraft carrier (about 30 tons), so the aircraft of the US Navy and the Marine Corps still use hoses to refuel.

Reference: Baidu aerial tanker encyclopedia

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