In 1932, Sir Alan Cobham, aware of experiments in the transfer of fuel in flight in the United States, decided to establish a company to refuel aircraft, pursuing purely commercial goals in civil aviation. In the USSR, the first attempts to refuel in the air date back to the early 30s of the last century. From 1933 to 1935, engineer A. Zapanovsky and pilot I. Belozerov, under the guidance of pilot engineer G. Altynov, conducted in-flight refueling experiments. Fuel was transferred from R-5 to TB-1 and from TB-1 to I-15 and I-16 fighters, as well as from one bomber to another.
In 1946-1947, in the 25 laboratory, LII considered the possibility of increasing the flight range of airplanes using refueling. In particular, they investigated the systems "bearing with excess", "from wing to wing" and "pin-cone". For testing the hitch mechanism of the wing system originally used Tu-2 and Yak-15, and then a pair of Tu-4. All filling equipment was placed in bomb bay.
Usually, refueling in flight is carried out by a pair of aircraft, one of which gives off fuel and is called a tanker (tanker), the other aircraft that receives fuel is called refueling (by plane, by helicopter). The most widespread refueling in the air was received by combat and military transport aircraft, which made it possible to significantly increase the range and duration of flights of aircraft, especially in naval aviation.
The most successful way of refueling aircraft in flight is the “pin-taper” scheme and using a telescopic rod. Each refueling system has its own characteristics and includes: units, devices, devices designed to transmit and receive fuel, distribute it among the tanks, control the filling process and monitor it.
Under the “pin-cone” scheme, the tanker aircraft releases a flexible hose with a receiving cone at the end. A telescopic bar is installed in the forward part of the aircraft’s fuselage, which is “fired” with compressed air and connected to the receiving cone receiving device. The contacting is carried out by the pilot of the fueled aircraft.
It is necessary to get closer to the aircraft being flown from below and to approach the cone of the tanker a few meters practically in a satellite jet, aligning the telescopic rod with it. With the approach to the tanker, the disturbed air fueled by the aircraft removes the coveted cone from the rod. It is very difficult to get into the "apple", moving with minimal acceleration, otherwise a miss will lead to a collision.
Usually, transport aircraft are converted into tankers, and there is also a variant of a suspended filling unit, located under the wing consoles or on the fuselage. Suspended refueling units can be equipped with almost any aircraft of the same type, which is a characteristic feature and advantage of such a system. The refueling system with outboard units provides pumping fuel with a capacity of 1000-4500 l / min, and the built-in refueling system - 1500-3000 l / min.
An airborne fueling system such as a telescopic rod is usually installed on heavy refueling aircraft. It uses a rigid telescopic bar of length up to 17 m, hinged on the tanker fuselage. At the end of the boom there are small aerodynamic controlled surfaces with which the operator on the tanker can direct the tip of the boom to the throat of the fuel receiver. In this scheme, the main role is played by the operator of the tanker refueling, which corrects the position of the aircraft being filled in the ranks by radio and with the help of a special signal panel.
When refueling, the aircraft being refueled approaches the tanker by means of a dogon with belittling and takes up a building position by the marks on the fuselage and by special lights on the tanker, operated by the operator. The stage of convergence of aircraft and maintaining the system of refueling during the period of contacting and pumping fuel for the pilot of the aircraft being filled is very difficult and requires special systematic training. At the same time, the fuel transfer rate is the highest and reaches l / min 4000-6000. A variation of the telescopic bar refueling system is a bar with a short 4-meter hose with a filling cone at the end. Such a hybrid system makes it easier for a pilot to maintain a place in the filling station.
One of the most complex aircraft refueling systems in the air is the "wing scheme". Wing refueling was widely used on the Tu-4 and Tu-16. At the beginning of the 50-ies, a variant of the wing refueling system was developed on a Tu-4 bomber. The practical experience gained on this plane allowed us to hope for the successful equipment of her and the Tu-16 jet bomber. In this case, the transfer rate reached 2000 l / min. One experienced Tu-16 was re-equipped to refuel in the same way as the MiG-19 fighter jets, but tests showed that it was inexpedient to use.
Perhaps the main advantage of the wing-in-air refueling scheme is the small weight of such equipment, and the installation of the refueling unit is flush at the wing tip, which does not degrade the aerodynamics of the aircraft.
On the Tu-16Z, a flexible hose 38 m long with a cable and a winch were placed in the technical compartment and the nose of the wing. Tu-16Z differed from the serial Tu-16 bomber with a short pipe mounted on the tip of the right wing console. The tanker could deliver up to 20 tons of fuel in flight. The Tu-16Z tanker was put into service in 1957, and a total of 114 Tu-16 bombers were converted into refueling tankers, and 16 vehicles of various modifications into refueling Tu-571ZA. In the naval navy almost all operating aircraft of this type were equipped with an in-flight refueling system.
In the 60-ies, the tanker Tu-16H, equipped with a cone-hose system for refueling supersonic Tu-22, entered service. This system was fully borrowed from the aircraft Myasishchev ZMS, only the volume of pumped fuel decreased. Subsequently, the Tu-16H tanker was modified and received the designation Tu-16НН. In addition to the refinement of the refueling equipment, the aircraft installed radio hangout equipment, which greatly simplifies the convergence of aircraft in the air. All Tu-16 aircraft in the Navy were equipped with such equipment.
In the second half of the 50-ies, on one of the production Tu-16, equipment was installed for refueling in the air using the "cone-rod" system, but already as a refueling aircraft. Despite successful trials, the Tu-16 front drills did not refine. The machine was used for testing the refueling system of the Tu-95KD and Tu-22KD missile carriers.
It was very important to increase the range of flights of Tu-16 of various modifications in naval aviation, flying mainly along routes over the ocean. Wing refueling aircraft is a very complex type of flight training, only pilots with excellent piloting techniques could master it.
The flight to refuel in the air consists of several stages: a meeting with an aircraft tanker, a convergence maneuver, a starting position for the hitch, contacting with a refueling hose, filling up and flying into a filling station, disengaging at the end of refueling. Meeting on the route with the aircraft tanker can be carried out on passing, counter and intersecting courses, which requires special methods of calculation and is carried out using visual observation and radio equipment of the aircraft.
The pilot of the refueling aircraft must first balance the speed with the tanker so that the tip of the refueling hose “stops” in the air, since he does not see the rest of the hose and the wing console of his aircraft. Then, creating periodically a small left roll, begins convergence with the hose. The particular difficulty of this maneuver lies in the fact that above the sea at the height of the sky and water merge into one blue heat haze. Therefore, without visible landmarks, it is very difficult to determine the speed of approach and the distance to the hose, especially since at the height the machine becomes inert and it is necessary to very accurately calculate the movement of the steering wheel and the control of engines. Approaching the hose with an excess in 2 m, the wing of the aircraft enters the terminal vortex from the wing of the tanker, and the plane is pushed out of this jet.
All maneuvers are monitored by the commander of the firing units located in the rear cockpit of the aircraft being fueled and giving the necessary commands. When the left wing of the wing exceeds the 2 m and is advanced to the 6 m to the left over the hose, the command of the firing unit commander begins “pushing” the hose down and a small maneuver to go to the right. At the same time, the hose slides along the lower edge of the wing and falls into a peculiar grip of the filling unit at the end of the wing console.
At the same time, the winch is turned on at the tanker, and the hose is pulled to the end pipe. According to the white marks on the hose, the commander of the firing units tells the commander how many meters are left before the end of the tip contacts the gripper of the filling unit.
At the moment when the rear metal tip reaches the grip, the microswitch turns on, pops up the nozzle from the filling unit and connects to the hose tip. Air is applied and the compound is sealed. At this time, the command "contact" sounds, and the commander of the fueled aircraft fills the engine with engines and literally jumps forward and takes up the order of refueling. At this time, the front end of the hose enters the end pipe, connects to the receiving device and is sealed. The command "turn on the pump". Fuel begins to flow into the hose and through the open valves on the refueled plane enters the corresponding tanks. Distributes the fuel to the tanks of the second pilot with a special remote.
The most dangerous moments may occur when the wing is superimposed on the hose and when the hose contacts the fueling unit. The slightest delay in giving gas to engines can lead to a cable breakage and possible overlapping of the filling hose around the end of the wing in the aileron region.
Such cases of hinge wing in the jet stream from the engines of the tanker sometimes ended in tragedy. So, only in two air regiments of the Air Force during the development of refueling in the air 15 crews crashed. The strongest stresses when performing refueling in the air are not maintained by everyone, and the doctors had to massively write off the flight personnel of the Tu-16 for health reasons.
On this occasion, a special commission was established to investigate the causes of the disease of the pilots, and found that the psycho-physiological load on the body increases dramatically when refueling: the pulse rate increases to 186 and even 220 beats per minute, with the 76-80 standard, the respiration rate is 64 sigh , against 15-16 in calm conditions. Significantly increased body temperature, began intense perspiration. As a result, one refueling resulted in an average loss of 5% of the pilot’s weight. The man was so exhausting that he often simply remained exhausted, and only the second pilot could come to his aid.
But the tasks facing the Air Force did not allow abandoning flights with refueling. In the second half of the 50's, the US Navy began to show particular activity. Almost every day, American scouts flew along our maritime border, often breaking it. In the northwestern Pacific Ocean, a powerful group of US warships constantly plied. To suppress the activities of the 7 fleet near our shores, a military air base was built in the area of Sovetskaya Gavan, where the Tu-16 air group was stationed. It was equipped with a Tu-16X, equipped with cruise missiles "Comet". A little later, the Tu-16K-10 complex with the K-10 missiles appeared.
Almost every flight to the ocean was accompanied by the interception of Soviet missile-carrier patrol fighters from aircraft carriers. The missile carrier Tu-16K-10 was equipped with a very powerful EH radar that could detect aircraft carriers at a distance of 400 km, so the fleet command sometimes used these machines for reconnaissance in the northwestern Pacific. To do this, the air group was relocated to Kamchatka. The task was set: to reconnoiter the ocean area at a distance of more than 1000 km from the Kuril ridge.
Given the vast expanses of the ocean, the command of the Pacific Fleet attached particular importance to training the crews of the reconnaissance squadron and missile-carrying aircraft to refuel in the air. According to calculations, one passing refueling increased the range of the Tu-16 to 2000 km, and the second, oncoming, added almost 3500 km. The duration of the flight of the Tu-16 with two refueling reached 15 hours.
Electronic reconnaissance equipment allowed the crew to locate an aircraft carrier at a distance of almost one and a half times the target detection range by the aircraft carrier itself, which made the scout descending “under the antenna lobe” of the ship’s radar undetected, and presented an opportunity to suddenly go to the target and photograph it from a low altitude.
Imagine how much trouble there was on an aircraft carrier when the red star Tu-16 flashed over the deck. Here, as A. Beloborodko recalls, is one of the flights: “During the next reconnaissance mission in the northwestern Pacific, we flew with the tanker Tu-163 from the Yelizovo airfield, in Kamchatka. Following a pair of clouds, we refueled and continued to fly at an altitude of 10000 m. When flying in stratified clouds at a distance of more than 1000 km from the coast, the tail protection station suddenly issued a signal that the aircraft from the rear hemisphere was radiated with a fighter radar. I gave the command to the stern shooter to put passive interference from the dipole reflectors. I determined from the tone of the signal siren that the fighter was approaching ... And suddenly the signal of the siren became continuous. This meant that the fighter's radar sight captured our aircraft and its computing unit produces data for launching rockets. The score went in seconds. I gave the command to the production of continuous interference, I "threw" a heavy car in a sharp turn with a decrease. Only such a “pirouette” helped to bring down the fighter’s auto-tracking radar. ”
Needless to say, such flights, given the complexity of air navigation in flight over the ocean and several exhausting refueling stations, and even meetings with "unidentified fighters" were far from easy. Aviation veterans believe that in terms of crew losses, in terms of physical and emotional stress of flight crews, refueling in the air can only be compared with war, while others compared psycho-emotional stress with space flight.
Despite all the complications of the wing-in-flight refueling scheme on the Tu-16, the crews worked hard and with time mastered this most complicated form of combat training. In the Navy, airborne wing refueling was practiced until the decommissioning of the Tu-16.
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