Today, many have seen on TV or on the Internet stories about such an interesting aircraft as a tiltrotor, someone has read about them in magazines. What are these interesting machines? Tiltrotoros are aircraft that are capable of vertical take-off and landing (like conventional helicopters), but are also able to carry out long horizontal high-speed flight, which is typical for aircraft. Since such aircraft are not fully airplanes or helicopters, this affects their appearance. In addition to the fact that these aircraft are characterized by different flight modes, they often have to make compromises when creating and designing them.
It is worth noting that dreams of building an aircraft capable of vertical take-off and landing at the same time as high-speed horizontal flight have as long a history as dreams of flying in general. The first projects of something similar were proposed at one time by Leonardo da Vinci. The very idea of \u200b\u200b"crossing" a fairly fast, but limited in terms of flight modes and basing conditions, aircraft and a much less high-speed, but unpretentious helicopter in terms of take-off and landing places, occupied the minds of designers and the military for many years. However, such devices have been able to achieve any noticeable development only recently.
Work on tiltrotor aircraft, which, by turning propellers, could be converted from a helicopter to an airplane and vice versa, was carried out in many countries of the world. The designers of almost all states with a developed aviation industry have been working on such machines for more than half a century. The first works in this area can be attributed to the 1920-1930s of the last century. They worked on the creation of a tiltrotor in pre-war Europe, during the war they worked on a project of such machines in Germany. In the 1970s, in the USSR, the Mil Design Bureau was working on the project of the Mi-30 tiltrotor, which never took to the skies. As a result, some success in their creation was achieved only in the USA. The only commercially produced Bell V-22 Osprey tiltrotor today is in service with the US Marine Corps. Its development by Boeing and Bell took more than 30 years.
The project of the American tiltrotor VZ-2
According to its scheme, convertiplanes can be conditionally divided into 2 main classes, each of which is characterized by its own specifics and its characteristic problems of converting and transmitting traction developed by the power plant of the machine. We are talking about convertoplanes with a rotary wing and convertoplanes with rotary screws.
Rotary wing aircraft combine the characteristics of multi-engine aircraft, in which the motors are located on the wing consoles in a fixed position, with the capabilities of vertically taking off and landing helicopters. This technical solution makes it possible to achieve ranges and flight speeds typical for aircraft (also the ability to transport cargo), along with the possibility of vertical takeoff and landing. During takeoff, the wing of these aircraft is set to a vertical position, and the propellers create the thrust necessary for the takeoff of the machine. During the transitional flight regime, the wing gradually returns to the horizontal position. After returning to a horizontal position, all the lift is created by the wing, and the propellers provide the thrust necessary for the horizontal movement of the apparatus.
At one time, a number of American aircraft manufacturers, as well as one Canadian company, experimented with such devices, some of their experiments can be considered quite successful. For example, the American convertiplane with a rotary wing X-18. The X-18 tiltrotor had a rectangular fuselage and a high wing of small span. In the middle part of the wing, 2 powerful Allison T40-A-14 turboprop engines were mounted, developing a power of 5,500 hp. each. These engines were equipped with Curtis-Wright three-bladed counter-rotating turbo-electric propellers (the diameter of the propellers was 4.8 meters).
Convertible X-18 with rotary wing
During the takeoff of the machine "in a helicopter" the entire wing of the tiltrotor rotated along with the engines (around its longitudinal axis by 90 degrees). At the same time, a standard aircraft takeoff was used to take off the apparatus with a maximum load. In addition, in the tail section of the aircraft there was an additional Westinghouse J-34-WE turbojet engine, which developed a thrust of 1530 kgf. Its jet stream could change its direction in the vertical plane, which significantly improved the controllability of the tiltrotor at low flight speeds.
In 1958, the first and, as it turned out later, the only prototype X-18 was made. This tiltrotor went through a fairly intensive cycle of ground tests, after which in 1959 it was transferred to the Research Center. Langley, where he first took to the air on November 24, 1959. Before the completion of flight tests in July 1961, the X-18 tiltrotor managed to complete about 20 flights. The main reason for the end of its tests and the subsequent curtailment of the program was a malfunction in the mechanism for changing the pitch of the propeller, which occurred on the last flight of the apparatus, as well as the fact that its engines "were not interconnected." During one of its further ground tests, the X-18 tiltrotor was destroyed and ended its life already in a landfill. However, it is worth noting that this tiltrotor made it possible to collect a sufficient amount of data that was necessary to build a heavier and more advanced XC-142 tiltrotor with 4 engines.
The second most common type of tiltrotor can be called models with rotary screws. They have become more widespread, at least among experimental aircraft exactly. The disadvantage of such models in comparison with classical helicopters is the need for wings of a sufficiently large span. This is due to the fact that on such devices, 2 rather large diameter screws are most often mounted side by side. This requires an increase in the area that is used for takeoff and landing. Since the design of many convertiplanes uses power plants consisting of several engines, which set the propellers in motion, the failure of one or several of them at once can have catastrophic consequences for the device. Given this, in order to prevent a catastrophe in the design of multi-engine tiltrotors, one can often find cross transmissions that make it possible to drive several propellers from just 1 engine, which in turn leads to an increase in the mass of such devices.
Bell V-22 Osprey with rotary engine nacelles
It is worth noting that it is usually not the screws themselves that are turning, but the nacelles with them, as is implemented on the only serially produced tiltrotor Bell V-22 Osprey. This aircraft, which is in service with the US Marine Corps, is equipped with 2 Rolls-Royce T406 engines with an HP 6150 power. each. The engines are located in special nacelles at the ends of the wing and can rotate up to 98 degrees. Three-blade propellers with trapezoidal blades are interconnected by a synchronizing shaft, which is laid inside the tiltrotor wing. This shaft also allows the Bell V-22 Osprey to land with only 1 engine running. In order to reduce the weight of the tiltrotor structure, about 70% of the device is made of composite materials based on glass and carbon fiber with an epoxy binder, which makes its design 25% lighter than its metal counterpart.
Since this tiltrotor must be based on areas of limited size, it is equipped with folding wings and propellers, which can reduce its width on the ground to 5.51 meters. The crew of the tiltrotor consists of 2 people, and 24 paratroopers with their weapons can be accommodated in its cargo compartment. The 11.6 meter diameter tiltrotor propellers are also made of fiberglass to reduce weight.
With the wing deployed, the width of the Bell V-22 Osprey at the ends of the blades is 25.78 meters. The length of its fuselage is 17.48 meters. The height of the machine is 5.38 meters, with vertically mounted engines it increases to 6.73 meters. The maximum takeoff weight is just over 27 tons, while the payload weight when using vertical takeoff is 5,445 kg. The mass of cargo on the external sling is 6,147 kg when using 2 hooks. The maximum speed of the tiltrotor in airplane flight mode is 483 km/h, in helicopter mode - 185 km/h. The practical flight range is 1627 km.
The factory crawler turned around and began to descend. Here she slid down the dry strip at the foot of the ridge. Her caterpillars touched the sand. Gurney opened the cap of the cone and adjusted the safety straps. As soon as the factory landed, he jumped onto the sand and slammed the cone-shaped cap behind him. He was joined by five of his personal guards who jumped out of the forward compartment. The rest freed the factory's transport anchorages. Its wings fluttered, parted and described the first semicircle, after which the huge factory crawler soared into the air and flew towards the dark strip. A thopter landed where she stood, then another, and another. Having landed people, they again rose into the air.
Frank Herbert, "Dune"
Heavier-than-air aircraft with vertical take-off and landing, which can still "hover" in place and still move quickly in a horizontal direction, has always been a tidbit for the military. Still - with the help of such a machine, the landing and evacuation of the wounded from the battlefield, the delivery of cargo and ammunition to soldiers are simplified; the device can be used to destroy separate targets, for reconnaissance and adjusting artillery fire.
PROTOTYPE MACHINE
The first attempt to use unusual propeller-driven vehicles in war was the use of gyroplanes (from the Greek autos - self and gyros - rotation). The gyroplane is a strange thing: outwardly it looks like an airplane without wings, but with a propeller similar to a helicopter. But, unlike the latter, the autogyro propeller rotates freely, in autorotation mode, creating lift; only the propeller is driven by the engine, pulling the car forward.
For the first time, the idea to build an apparatus of this type came to the mind of the Spanish aircraft designer Juan de la Sierva. Watching in 1919 how the three-engine biplane designed by him falls, he noticed that the propellers, under the influence of the oncoming air flow, began to autorotate, that is, to rotate spontaneously. Further reasoning was simple: if the biplane had a large autorotator main rotor, then the test pilot could survive!
After a series of failures, Juan managed to construct a fairly well-flying autogyro (model C-4, 1923), and a little later - a demonstration model C-8, which made a splash in Europe. On the S-8, the designer flew Paris-London. Soon after that, gyroplanes appeared in the USSR (1929, designed by engineers Kamov and Skrzhinsky), then in Great Britain, and later all other leading countries of the world began to design similar machines.
FIRST STEPS
Years passed. Autogyros at the combat post were replaced by helicopters, but the latter had one serious drawback - a relatively low horizontal speed. The asymmetric blowing of the rotor blades (they moved either along the oncoming air flow or against it) led to the fact that the "ceiling" of the helicopter speed by the end of the 50s was approximately 300 km / h - and this despite the fact that the aircraft could already fly at three times the speed of sound! Experts in aerodynamics warned: it is impossible to infinitely increase the number of revolutions of the main rotor, since this can cause flutter (self-excited oscillations of parts of the aircraft), which will lead to loss of stability and controllability, or even to destruction of the structure. What to do? Maybe it's worth equipping a helicopter with airplane wings? Eureka!
However, the new is just a well-forgotten old, because the first experiments with aircraft of the combined scheme were undertaken back in the 1930s. And now, two decades later, attempts to create hybrids were again made by the USA, Great Britain, France, Canada and a number of other countries - almost simultaneously.
In an attempt to reach high speeds on convertible aircraft, the designers went in two ways. In the first case, the machine (rotorcraft) had a main rotor, like a helicopter, plus another screw (or several screws) in a vertical plane, like an airplane. The second scheme turned out to be much more interesting: the helicopter was equipped with rotary motor groups on the wings, that is, right in flight it was possible to turn a helicopter into an airplane and vice versa. The latest design was named "tiltrotor".
HYBRID FOR SWAT
Back in October 1936, the defense of the Sokol project, an aircraft with a rotary wing, took place at the Moscow Aviation Institute. Student Kurochkin managed to anticipate the development of convertiplanes three decades ahead - only in 1964, after much research, after hard work of designers, aerodynamicists and engineers of the American companies Vouht, Ryan and Hiller, the XC-142A military transport rotorcraft was created. It was equipped with a 20.6 m swing wing with flaps and slats, hinged to the fuselage.
The synchronous mechanism rotated the wing at an angle of up to 106 °. Four turboprop engines were attached to the plane, which produced 2850 hp during takeoff. and provided a tiltrotor top speed 604 km/h. The nose housed a double cockpit with ejection seats. The XC-142A could be lifted into the air and landed both in a helicopter (from place / to place) and in an airplane, with a run or run.
| ROTOR WINGS: GOING FOR PROFIT |
| The idea to cross a helicopter with an airplane occurred to many designers immediately after the Second World War - engineers from the USA, France, Great Britain, Canada and a number of other countries, in pursuit of super profits from the operation of a high-speed commercial helicopter, joined the race of designers. Appropriate amounts were spent on this business: for example, the American airline McDonell spent more than $ 50 million on the development of a prototype, plus another $ 75 million paid for its modification. The first such device, which received the name "rotorcraft", was lifted into the air by Soviet pilots - it was TsAGI-11EA (1936). But the war stopped experimental development, and quite a bit is known about TsAGI, so American aviation historians consider their brainchild, the McDonnell XV-1 tiltrotor built in 1955, to be the “first-born”. Not so long ago, by the way, the American magazine Aviation Week reprinted the front page of an old newspaper, through which this “new, hitherto unprecedented type of aviation technology” famously flew by. Like any helicopter, the XV-1 was equipped with a main rotor, and from the aircraft it got wings and a pushing propeller. In horizontal flight, the thrust was created by a rotary main rotor and a propeller. In the event that the propeller was disconnected from the transmission, the wing created lift for the car. The landing gear was replaced with steel skis, which was not surprising, since McDonnell took off like a helicopter. The Continental engine at the same time gave all the power to the main rotor of the motor, which simultaneously worked on the air compressor. Compressed air and fuel were supplied to the ends of the blades - that is, the Americans actually used a jet drive. |
Canadian designers, in turn, to ensure the stability and controllability of the tiltrotor in hover mode, provided their offspring CL-84 with two tail coaxial propellers located behind the keel and stabilizer. After a vertical takeoff, they stopped, the rotors turned, the wing was fixed, and after 10 seconds, the CL-84 was already rushing forward, picking up a speed of 500 km / h.
At the same time, a number of convertiplanes from various American companies appeared: the theme was fashionable, the US Air Force promised to buy everything that would pass at least initial tests, and the engineers happily plunged into work. One of the most original designs was the Bell X-22A with not two, but four YT58-GE-8D engines with a total power of 1250 hp. On this tiltrotor, for the first time in the short history of such machines, the propellers were placed in circular casings, which significantly increased efficiency both in vertical movement and in horizontal flight. The first of two manufactured Bells crashed (the pilot survived) on landing during early testing, but the second successfully flew from 1966 to 1988, although mass production the model didn't work.
Europe lagged behind a little in this matter, but original developments also occasionally appeared. Perhaps the most famous European tiltrotor of the 1960s was the French Nord 500 Cadet - small, nimble, light (only 1300 kg in running order). At the Paris Air Show in 1967, the military liked the single-seat tiltrotor, and Nord was asked to make several copies for reconnaissance and surveillance. True, the tests dragged on; the first flight of the Nord 500 was made only in 1968, a year later it was “purged” in a wind tunnel, and then the need for such a machine somehow disappeared. Reconnaissance could also be carried out on a compact helicopter.
TAIL FORWARD
Canadair CL-84 has already been briefly mentioned in this article, but it should be given a little more attention. Still, this model went beyond a simple test program: the Ministry of Defense ordered several vehicles from the manufacturer to be put into service.
Canadair showed interest in convertiplanes in 1956, and by 1965 produced its own hybrid, the CL-84 Dynavert. The aircraft, which accommodated 12 people (plus 2 crew members), had a traditional round fuselage in cross section. A very interesting point in the design of the CL-84: the wings of the device were able to turn at an angle of up to 100 °, which made it possible not only to hover in place, but also to fly tail forward at a speed of 56 km / h!
The first demonstration of a tiltrotor hovering in the air took place on May 7, 1965. After 145 flight hours, the device crashed (September 12, 1967), but the Canadian Ministry of Defense had already ordered three copies of the improved CL-84-1 aircraft, giving it the army designation CX-84. The changes affected turboprop engines, the power of which was increased, as well as the volume of fuel tanks. There are also two additional external suspension points. The armament of the army version was a 7.62 mm machine gun, a 20 mm cannon and 19 missiles.
The first CX-84 took off on February 19, 1970, in February 1972 made several landings on the Guam underwater surveillance system control ship, but also crashed in August 1973. The second aircraft participated in the program sea trials underwater surveillance systems as part of the air wing of the Guadalcanal ship in March 1974, but the Canadian military apparatus did not dare to adopt.
ROTOR WING FOR KHRUSHCHEV
In the USSR, with its vast expanses and lack of a developed airfield network, the prospect of using heavy-duty rotorcraft seemed to be saving - both for military and civilian tasks. In the mid-1950s, the Design Bureau of the famous aircraft designer Kamov made a revolutionary decision: to build a transverse aircraft with two pulling propellers and two main propellers at the ends of the wings. For domestic aviation, this type of aircraft was new and combined the advantages of a helicopter capable of taking off and landing vertically, and an aircraft with its large payload, range and flight speed. But first of all, the tiltrotor was created to transport paratroopers, military equipment and large loads.
In 1961, OKB test pilots set eight world records on the Ka-22, including speed (356.3 km/h) and maximum weight cargo lifted to a height of 2000 m (16,485 kg). The characteristics of the rotorcraft are also curious: maximum takeoff weight - 42,500 kg; the dimensions of the cargo compartment are 17.9 x 2.8 x 3.1 m. For comparison: the maximum take-off weight of the largest Ka-25 helicopter at that time was 7000 kg. However, the rotorcraft did not go into the series. Not the last role in this was played by two crashes of experimental vehicles, after which the leadership of the Air Force began to treat the rotorcraft with distrust.
The first crash occurred at Juzala Airport, where Rotorcraft 01-01 was landing. At the same time, an Il-14 regular plane landed on the emergency lane, the pilot of which later wrote in an explanatory note about the disaster: “10-15 seconds before the crash, I was on a straight line, coming in to land with a heading of 240 on the emergency lane. The rotorcraft was in front of me at a distance of 300–400 meters and 50–80 m lower. No deviations from the normal gliding trajectory of the rotorcraft were observed. At an altitude of 50–70 m, the rotorcraft slightly scrambled (I saw this by changing the projection of the rotorcraft when viewed from behind and from above), then began to turn to the left with a simultaneous flip onto its back. The nature of the reversal is slow at first, then vigorous with a transition to a steep negative dive. The rotorcraft hit the ground, disintegrated and burst into flames. Two or three large parts flew off from the center of the flame in a southerly direction, leaving a plume of dust on the ground. Of the seven members of the tiltrotor crew, no one escaped. On the steering wheel of the destroyed car, they found the hand of the pilot Efremov, which they could unclench with great difficulty ...
For non-pilots, it is worth clarifying that pitching is the movement of an aircraft when its nose is slightly "raised" relative to the local horizon.
The second incident was just as tragic. “There were a lot of witnesses to the disaster - people were walking and driving to work at this time,” wrote one of the members of the Kamov Design Bureau. - Rogov and Brovtsev died. The rest of the crew spoke about the beginning and development of the disaster. Takeoff "like an airplane", a calm flight at an altitude of 1000 meters for 15 minutes. Speed up to 310 km/h. When planning and reducing the speed to 220-230 km / h, a spontaneous right turn suddenly began, which could not be parried with the left pedal and the steering wheel. The car turned almost 180 ° when Garnaev intervened in control and, thinking that the turn was the result of a difference in pitch of the pulling screws, unloaded them, sharply increasing the angles of the common pitch of the rotors by 7–8 °. The rotorcraft slowed to starboard, rolled onto its nose and began a steep dive. Having lost 300–400 m of altitude, the machine reduced the dive angle to 10–12 °, but at that time the flight mechanic dropped the canopy flap, it hit the right propeller blade, which broke off, and unbalanced centrifugal forces tore off the entire right engine nacelle ... "
In general, we can say that the work on aircraft with the possibility of a helicopter launch and flight "like an airplane" did not cause a revolution in aircraft construction. But the knowledge acquired by test pilots, who flew unusual machines in two flight modes at once, was useful to their colleagues very soon - a few years later they appeared jet planes vertical takeoff and landing.
Science fiction writers did not pass by such aircraft either - machines with rotary engine nacelles can be found in many science fiction books, films and computer games.
| In what to play? |
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FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES
The invention relates to transport engineering, and more specifically to convertiplanes having lifting rotors, like transverse helicopters for vertical takeoff and landing and for flying on an airplane after converting the device.
BACKGROUND OF THE INVENTION
A tiltrotor is known, called a vertical takeoff and landing aircraft (VTOL) V-22 Osprey, containing a fuselage, wings and a stabilizer with control surfaces installed according to an aircraft scheme, equipped with a hydraulic drive for turning the rotors for converting and controlling the apparatus.
a) the total weight of the tiltrotor (mainly due to heavy engines, synchronizing shaft and angular gearboxes, hydraulic conversion control drive and swashplate control (AP)) is large;
b) a fixed horizontally located wing creates a large shading resistance when it is blown by rotors in helicopter mode during vertical takeoff and landing.
This results in the following shortcomings:
a) the inability to land a tiltrotor on the water;
b) payload weight during vertical takeoff and landing is only 25% of the curb weight;
c) the presence of a synchronizing shaft and angular gearboxes complicates and makes the design heavier, requires additional power take-off of power plants for operation, reduces reliability due to the complexity of the design;
d) hydraulic drives for converting and controlling swashplates require additional power take-off of power plants, as a result,
e) increased fuel consumption during takeoff, landing, the entire flight.
An experimental tiltrotor is also known, called a vertical take-off and landing aircraft (VTOL) "XC-142A", containing a fuselage with a common rotary wing (tiltwing), as well as four propeller power plants located on the wing, in which roll control is carried out by a differential change in power engines, in yaw - by aileron deflection, in pitch - by a tail rotor of small diameter, horizontally mounted in the tail section. In this case, the wing rotates in the range of 100 degrees from the longitudinal axis of the VTOL aircraft.
The reasons preventing the achievement of the technical result mentioned below in the manufacture and use of the known tiltrotor are as follows:
a) engines are equipped with small diameter propellers;
b) for pitch control, a horizontal tail rotor and auxiliary mechanisms are used;
c) power to drive the tail rotor and hydraulic drives is taken from the power plants of the main rotors;
d) a hydraulic drive and auxiliary mechanisms are used to rotate the wings.
The consequence of this are the following disadvantages of the tiltrotor:
a) significant power of power plants (engines), and consequently, the weight of the engines, an increase in the area and strength of the carrier wing, and, consequently, an increase in its weight;
b) the tail rotor, hydraulic drive and auxiliary mechanisms complicate the design, reduce the reliability of the tiltrotor, increase its weight and reduce its energy efficiency;
c) it is impossible to take off and land from/to water;
d) increased fuel consumption in the hover mode and the entire flight.
SUMMARY OF THE INVENTION
The present invention is based on the ability to control a tiltrotor with reactive rotors solely using a helicopter-type swashplate (AP), without any additional devices such as elevators, rudders, ailerons, flaps and other mechanisms. In this regard, the design of the tiltrotor is greatly simplified.
It becomes possible to carry out maneuvers in helicopter mode solely by changing the thrust vector of the rotors by means of a swashplate (AS). Pitch control with the help of AP is provided by a synchronous change in the cyclic pitch of the blades, in roll - by a differentiated change in the total pitch of the rotor blades. The pedals are used for yaw by providing multidirectional thrust vectors of the rotors relative to the center of gravity of the tiltrotor exclusively in helicopter mode.
In airplane mode, the pedal rods are switched to the steering wheel, thereby performing the “aileron” control mode, with the combined control of the “elevators” in pitch, as on airplanes, the control of the entire apparatus in airplane mode is carried out according to the “joystick” principle. Pitch-throttle in cruise mode is used to increase or decrease airspeed.
Particularly clearly achieved technical results are manifested in a particular embodiment, in which:
consoles with rotors do not have an interconnection with each other, freely rotate on hinges, can be fixed in a certain position using friction and similar mechanisms in terms of the result achieved, do not have motors and hydraulic mechanisms for forced change of their position; consoles are controlled in the direction of the thrust vector of the rotors; the tail unit is not mechanized, it provides the direction of movement along the "aircraft" in passive stabilization of the direction of flight.
DETAILED DISCLOSURE OF THE INVENTION
The objective of the invention is to create a light tiltrotor with the following set of technical characteristics:
a) a range of more than 1000 km;
b) speed in airplane mode is not less than 500 km/h;
c) lightly loaded jet-driven rotors;
d) the possibility of vertical takeoff and landing from small areas and on horizontal surfaces unprepared for landing, allowing a slight slope;
e) the ability to take off and land on water.
The above problem is solved due to the fact that the tiltrotor contains:
fuselage (1);
fairings (19);
rotors (6) contain propellers (5) having blades (7) with jet engines (8) rigidly connected to columns (12) of consoles (2) by means of torsion bars (9) fixed on freely rotating shafts (10) of columns (12 ), in bearings (11);
jet engines (8) located in the cantilever part of the blades (7), having nozzles oriented towards the trailing edge of the propulsion blades (7);
swashplates (14) configured to change the total and cyclic pitch of the propeller blades (7) by changing the installation angle of said propeller blades (7);
The technical result achieved in the manufacture and use of a tiltrotor with the above technical specifications, is the sum of the following causally related effects:
a) the tiltrotor design is simplified in comparison with its analogue, namely, the vertical propeller, the stabilizer with movable aerodynamic planes and / or the active keel with steering planes are excluded, hydraulic or electrical systems are not required to turn the wings during conversion, no landing gear is required;
b) reduced the total weight of the tiltrotor;
c) increased reliability compared to convertiplanes and;
d) increased energy efficiency in aircraft mode, reduced fuel consumption in hover mode compared to convertiplanes and;
e) the ratio between payload mass and curb weight has been improved;
f) it is possible to take off and land from/to water and slopes up to<20*;
g) the method of controlling the tiltrotor is simplified.
The general reason that made it possible to achieve the above technical result is, first of all, the replacement of traditional propellers used in convertiplanes and jet propulsion, and the supply of both rotors with 2-channel swashplates, in place of 4-channel helicopter type.
The exclusion of hydraulic or other conversion mechanisms became possible due to the fact that the conversion occurs under the action of a force similar to the force on the helicopter rotor, which occurs through the swashplate, which affects the cyclically variable mounting angle of the blades. This force is the resultant aerodynamic force that affects the change in the position of the rotors in space; the change in thrust force is carried out by changing the total pitch of the blades by means of a swashplate.
The ability to change the cyclic pitch of the propellers in airplane mode allows you to vary the position of the tiltrotor in space, as a result of which no additional aerodynamic steering elements of the wings, keels and stabilizers are required.
The need for a tail rotor and steering planes is eliminated due to the fact that setting a different cyclic pitch on the left and right propellers in helicopter mode and a different total pitch of propellers in airplane mode allows you to turn the aircraft in any direction without using any additional means.
The use of jet propulsion instead of traditional turboprops allows to reduce the overall weight and dimensions in comparison with the layout, in which the power units are located at the ends of the consoles; the use of electronic synchronization of the rotation of the rotors by controlling the fuel supply to each rotor separately with feedback makes it possible to abandon the synchronizing shaft with angular gearboxes. And in comparison with the layout, in which the power unit is located inside the fuselage, the same result is achieved due to the absence of transmission and kinematic links between the power unit and the rotors.
In accordance with the present technical solution, the power plant of the jet propulsion unit is made in the aggregate of the rotor itself or in the form of an independent unit.
In one of the preferred embodiments of the tiltrotor rotors, the aforementioned air-jet propellers (5) are made in one piece with the rotor (6) and the aforementioned blades (7), while the aforementioned blades (7) contain a common input device (13) located near the shaft rotors (10), a longitudinal air duct of the blades (7) with a heat exchanger (21) located inside it for the evaporation of cryogenic fuel and an engine combustion chamber (8) with a jet nozzle. In more detail, the design and principle of operation of propulsors of this type are disclosed in the RF patent for utility model No. 95035.
In an alternative embodiment, the tiltrotor additionally contains an air blower or a gas generator, while the above-mentioned engine nozzles (8) are connected to the above-mentioned column (12) in the fairing (19) by means of air ducts located inside the above-mentioned propellers (5), and the above-mentioned column of rotors in the fairing (19) is connected with the outlet of the mentioned air blower or gas generator by means of an air duct, which ensures tightness in the places of swivel joints. This type of blade drive is similar to that used in the Sud-Ouest SO-1221 Djinn and Pegasus Pressure Jet Helicopter helicopters.
Tightness in the places of swivel joints is ensured by means of labyrinth seals.
As the aforementioned blower or gas generator, a jet turbocharger may be used. It is particularly advantageous if the jet nozzle of the turbocharger is provided with deflectors for controlling the thrust vector of the aft fuselage.
Preferably, the aforementioned blower or gas generator is placed inside the aforementioned fuselage (1). However, the possibility of installing a turbocharger or compressor inside a fairing connected to the fuselage is not ruled out.
Propeller blades can be of various designs with or without features that improve aerodynamic efficiency (blade torsion, tips, swept ends).
The aforementioned keel (4) is passive and does not have movable steering surfaces. Of course, the addition of the keel with steering elements is not excluded, but there is no urgent need for this.
The aforementioned stabilizer (3) is made passive, that is, it does not have aerodynamic elements with a variable angle of attack. Of course, the addition of the stabilizer with these aerodynamic elements is not excluded, but there is no urgent need for this.
The specific design of the stabilizer or keel is not critical, the stabilizer and / or keel can be made as a single element, or the stabilizer and / or keel can consist of two separate elements: right and left and upper and lower, respectively.
In order to improve aerodynamic efficiency, the stabilizer (3) may (optionally) be provided with tips (also called keel washers).
In a particularly preferred embodiment, the aforementioned consoles (2) can (optionally) be made in the form of wings. Wings may have a variety of airfoils, such as, but not limited to, flat, plano-convex, or biconvex airfoils. Wing sweep can be either forward or reverse, but reverse sweep is preferred.
Said hinges (18), by means of which said consoles (2) are connected to said fuselage (1), may (optionally) be provided with means ensuring, in the absence of a significant horizontal component of the flight speed, that said consoles (2) are set in a neutral position, appropriate for takeoff, landing and/or hovering.
In a particularly preferred embodiment, the aforementioned hinges (18), axles or half-axes, on which the consoles are fixed and through which the said consoles (2) are connected to the said fuselage (1), are equipped with friction clutches with electromagnetic control for fixing in a given position. The presence of a trimmer-lock allows you to reduce the complexity of piloting after setting the desired direction of the course, after leveling the tiltrotor.
The aforementioned hinges (18), on which said consoles (2) are mounted, can (optionally) be placed above the tiltrotor's center of gravity. This arrangement provides a better balance of the aircraft in roll and pitch, compared with an alternative arrangement, when the consoles are fixed below the center of gravity.
To reduce the space occupied, when stored in a hangar or when parking, the aforementioned consoles (2) can be (but not necessarily) made removable or collapsible.
Traditional controls (16) can be used to control the tiltrotor, including, in particular, traction and rocking chairs, providing communication of the aforementioned swashplates (14) with controls (16) located in the cockpit, in particular with servos connected to the control unit , while the control unit is configured to receive control signals and transmit telemetry via wireless communication channels.
Alternatively, the aforementioned fuselage (1) may (but need not) be made integral with the cockpit, with the control carried out directly by the pilot using controls located inside the cockpit. The control means may include rods and rockers that provide communication of the aforementioned swashplates (14) with the controls (16). The controls (16) are located in the cockpit and can be a steering wheel, step-gas and pedals.
Since the landing and takeoff of a tiltrotor can be carried out at almost zero landing speed (both vertical and horizontal), the landing gear is not required, and instead of them, the mentioned fuselage (1) can be equipped with floats-supports (20) for landing (on water or other surfaces without a slope or with a slight slope) or other supporting elements.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 schematically shows the above-described tiltrotor side view.
Figure 2 schematically shows the above tiltrotor top view.
Figure 3 schematically shows the above-described tiltrotor front view.
Figure 4 shows a schematic diagram of the mover with elements of the swashplate, torsion bar, rotor column, the possibility of supplying fuel to the mover and the movement of air in the duct supercharger.
IMPLEMENTATION OF THE INVENTION
Figure 1 schematically shows a tiltrotor side view, which contains a fuselage 1 with a cockpit, attached to it rotating around the transverse axis of the fuselage wing consoles, on which jet propulsion units are fixed in one piece; passive stabilizer and keels 4 are attached to the extreme tail section; floats 20 are attached in the lower middle part; in the cockpit of the tiltrotor are the controls; behind the cabin, in the rear compartment, there may be necessary for launching and operation: starting auxiliary power unit (APU), fuel tank (cylinder), on-board power battery, and other structural components; on the consoles 2 and inside the fairings 19 there are rotor columns extending from the fuselage to the fuel supply communication console, an ignition circuit, a starting air line, control rods with mixers and intermediate control rockers, and helicopter-type swashplates (not shown). The execution and placement of the equipment necessary for launching and operating is not structurally fundamental, since it depends on the design solution of the problem.
In FIG. 2 shows: the fuselage 1 with structural elements, such as: the cockpit and passenger cabin with duplicated tiltrotor controls 16, the center of gravity 17, the rear fuselage with the stabilizer 3 and keels 4, the center section with hinges 18 consoles 2, on which fairings 19 are fixed with columns of rotors and rotors 6 fixed on them, floats-supports 20.
In FIG. 4 shows fairings 19 with columns 12 of rotors with a shaft 10 and bearings 11 placed in them, the columns include: the housing itself, on which the elements of fuel transfer from the non-rotating part to the rotating part of the rotor are fixed through the shaft 10 connected to the column housing by means of bearings 11, swashplate 14, a torsion 9 is also fixed on the rotor shaft, which combines the blades 7 of the propellers 5 into the rotor 6. In the region of the rotor shaft, the input device of the propellers 13 is located, which is strictly oriented along the flight axis in airplane mode. Also shown is the propeller 5 itself with elements of air channels, a heat-exchange evaporator-spar 21 and an air-jet engine 8. The direction of the air in the duct supercharger and the principal supply of fuel to the jet engine are also shown schematically.
The tiltrotor contains a fuselage 1 with cantilever wings 2, independently and freely rotating in the transverse axis in the region of the center of gravity, in the range from -10 to 110 degrees relative to the longitudinal axis, as well as two jet propulsion 5 of two rotors 6, rigidly fixed along the axis, on each from rotary consoles 2. In the rear part of the fuselage there is a passive stabilizer 3 and a keel 4, which does not have steering planes, which acts as a passive directional stability. The tiltrotor fuselage 1 in the middle part also has two additional float-supports 20, which together with the fuselage 1 serve as a landing surface for landing and takeoff from any horizontal surface up to the water. The tiltrotor control device contains only a helicopter-type swashplate 14, located in the immediate vicinity of the propellers, in fairings 19 and combined into a single control circuit, by means of rods and rocking chairs, with a steering wheel, step-gas and pedals 16, located in the cockpit.
Console 2 is made removable. Removability of the consoles can be provided by one of the well-known quick-release technical means, for example, by means of base pins with subsequent locking or with the help of base joints and fixing screws, etc.
Takeoff, flight and landing tiltrotor performs as follows.
The starting auxiliary power device (APU) is launched, which is located in the fuselage (1) and which provides the necessary volume and pressure of air to start jet propulsors (5), which are simultaneously supplied with fuel and high voltage to the glow plug, consoles (2) with jet propulsion (5) rotors (6) are in a vertical position. After the propellers are started and they reach the operating speed of the rotors, a vertical take-off is performed in helicopter mode with a climb to gain speed in level flight and a transition to airplane mode (conversion). After gaining speed in airplane mode, the tiltrotor continues horizontal flight at a given altitude with cruising speed. Helicopter landing is carried out in the reverse order: forward speed reduction to helicopter mode speeds, conversion to helicopter mode, selection of a landing site, landing on floats 20, rotors 6 stop, fuel supply cut off.
Maneuvering tiltrotor on takeoff, in flight and landing is provided by changing the position of the consoles (2) with the rotors (6) using the control of the swashplates (14) from the cockpit, the controls 16: steering wheel, step-gas, pedals. Due to the fact that the force vector drags the consoles to take a position corresponding to it in space, due to changes in the pulling force vector by the propellers-rotors, by means of a helicopter-type swashplate (14) controlled by controls (14) from the cockpit, the tiltrotor itself is controlled as a whole.
The movements of the helm, step-throttle and pedals pass through 2 mixers and work as follows:
1) the steering wheel "from itself - towards itself" in helicopter and airplane mode changes the pitch of the tiltrotor, acting on the rotors in synchronous motion of both swashplates. Provides conversion from helicopter to airplane mode and vice versa;
2) the movement of the steering wheel "left-right" in helicopter mode changes the roll, affecting differentially the common pitch of both rotors. In airplane mode, it works in the “ailerons” function, the function appears when converting by switching the rods automatically from the pedals to the steering wheel;
3) the pedals work only in the helicopter mode in the "yaw" mode and affect the swashplate differentially;
4) Pitch-throttle lever influences the synchronous collective pitch and overall adjustment of the fuel supply automatically to the propulsion rotors. Serves for takeoff in helicopter mode and maneuvering vertically, in airplane mode - to increase or decrease forward speed.
Stabilization of flight along the course in airplane mode is carried out by the stabilizer (3) and keel (4) according to the principle similar to the plumage of an arrow.
Below are the main flight data of the proposed tiltrotor, obtained in the process of detailed design.
BIBLIOGRAPHY
1. Convertible V-22 "Osprey" // http://ru.wikipedia.org/wiki/Bell_V-22_Osprey.
2. Convertiplane "XC-142A" // Ruzhitsky E.I. American VTOL aircraft. M.: ACT: Astrel, 2000.
3. RF patent for utility model No. 95035.
1. Tiltrotor, containing:
fuselage (1);
stabilizer (3) and keel (4) made with the ability to maintain directional stability in aircraft mode and located in the rear fuselage (1);
consoles (2) installed near the center of gravity (17) on both sides of the fuselage (1) and connected to it by means of hinges (18), providing the ability to change the angle of rotation in the range from 100 to -10 degrees relative to the horizon independently of each other;
fairings (19);
the columns (12) are rigidly connected to the consoles (2) and are closed with fairings (19);
rotors (6) contain blades (7) with jet engines (8) connected to columns (12) of consoles (2) by means of torsion bars (9) fixed on freely rotating shafts (10) of columns (12) in bearings (11) ;
jet engines (8) located in the console part of the blades (7), having nozzles oriented towards the trailing edge of the blades (7);
swashplates (14) configured to change the total and cyclic pitch of the blades (7) by changing the installation angle of said blades (7);
control means (16) configured to change the total and cyclic pitch of said blades (7) of the rotors (6).
2. Tiltrotor according to claim 1, characterized in that the aforementioned blades (7) contain a common inlet (13) located near the rotor shaft (10), a longitudinal air duct of the blades (7) with a heat exchanger (21) located inside it for evaporation of cryogenic fuel and the combustion chamber of the engine (8) with a jet nozzle.
3. The tiltrotor according to claim 1, characterized in that it additionally contains an air blower or a gas generator, while the above-mentioned engine nozzles (8) are connected to the above-mentioned column (12) in the fairing (19) through air ducts placed inside the above-mentioned blades ( 7), and the aforementioned column of rotors in the fairing (19) is connected with the outlet of the said air blower or gas generator through an air duct that ensures tightness at the hinge joints.
4. Tiltrotor according to claim. 1, characterized in that the tightness in the places of swivel joints is ensured by means of labyrinth seals.
5. Tiltrotor according to claim 3, characterized in that in it the aforementioned air blower or gas generator is a jet turbocharger, and its jet nozzle is equipped with deflecting elements for thrust vector control.
6. Tiltrotor according to any one of paragraphs. 3 or 5, characterized in that the aforementioned air blower or gas generator is placed inside the aforementioned fuselage (1).
7. The tiltrotor according to claim 1, characterized in that the aforementioned keel (4) is passive in it, does not have movable steering planes.
8. Tiltrotor according to claim 1, characterized in that the aforementioned stabilizer (3) is passive in it.
9. Tiltrotor according to claim. 1, characterized in that the aforementioned stabilizer (3) is a single element.
10. Tiltrotor according to claim 1, characterized in that in it the aforementioned stabilizer (3) is equipped with wingtips - keels (4) (keel washers).
11. Tiltrotor according to claim 1, characterized in that the aforementioned consoles (2) are made in the form of wings.
12. A tiltrotor according to claim 11, characterized in that the aforementioned wings are made with a flat, plano-convex or biconvex airfoil.
13. Tiltrotor according to claim. 11, characterized in that the above-mentioned wings are made with reverse sweep.
14. The tiltrotor according to claim 1, characterized in that in it the aforementioned hinges (18), through which the aforementioned consoles (2) are connected to the aforementioned fuselage (1), are equipped with means that ensure, in the absence of a significant horizontal component of the flight speed, the installation of the aforementioned consoles (2) in the neutral position corresponding to the takeoff, landing and/or hover mode.
15. The tiltrotor according to claim 1, characterized in that in it the aforementioned hinges (18), through which the aforementioned consoles (2) are connected to the aforementioned fuselage (1), are equipped with friction clutches with electromagnetic control for fixing in a given position.
16. Tiltrotor according to claim. 1, characterized in that the above-mentioned hinges (18), on which the above-mentioned consoles (2) are installed, are located above the center of gravity.
17. Tiltrotor according to claim 1, characterized in that the aforementioned consoles (2) are removable or foldable for compact parking.
18. Tiltrotor according to claim 1, characterized in that the aforementioned controls include rods and rockers that provide communication of the aforementioned swashplates (14) with controls (16) in the cockpit.
19. Tiltrotor according to claim 1, characterized in that in it the aforementioned fuselage (1) is made integral with the cockpit.
20. Tiltrotor according to claim 1, characterized in that in it the aforementioned controls include rods and rockers that provide communication of the aforementioned swashplates (14) with controls (16).
21. A tiltrotor according to claim 20, characterized in that said controls (16) are located in the cockpit and represent a steering wheel, step-gas and pedals.
22. Tiltrotor according to claim. 1, characterized in that in it the aforementioned fuselage (1) is equipped with floats-supports (20).
Similar patents:
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The invention relates to the field of aviation, in particular to the structures of helicopters. The tail of the helicopter contains a fenestron with a multi-bladed propeller (4) with blades (3) and, if necessary, vertical fins (1.2). The flow straightening stators (5) of the fixed blades are arranged in a star configuration parallel to the plane of the propeller, downstream of the propeller (4). The ring (2.1) of the fenestron is enclosed in a composite structure of an outer erosion-protective surface layer (7.1, 8.1) made of hard plastic or plastic composite material and at least one subsequent layer (7.2, 8.2) of an elastomeric damping material. The fenestron ring alternately contains two layers of hard plastic and two layers of an elastomeric damping element. EFFECT: reduced noise level of the tail unit. 9 w.p. f-ly, 9 ill.
The system for real-time simulation of the environment of the engine of the aircraft contains a digital computing device, a device for simulating in real time a part of the environment of the engine and the aircraft. The digital computing device contains an input for receiving data from sensors or an aircraft, an output associated with the engine or aircraft drives, a control module, and a selection module. The simulation device contains a digital input and output, a control module, connected in a certain way. A real-time simulation mode of the environment of the engine and the aircraft is provided with the possibility of turning it off during the flight. 5 z.p. f-ly, 4 ill.
The group of inventions relates to a helicopter, a method and a device for reducing vibration. The helicopter contains a structure including a fuselage, a rotating system, and a vibration reduction device. Vibration reduction device comprises electrohydrostatic drives, electrohydrostatic drives oscillation means, dynamic change sensors, processing means. To reduce vibration in the helicopter structure, electrohydrostatic drives are connected between parts of the structure that are moving relative to each other, cause the drives to oscillate at a frequency corresponding to the excitation frequency, form signals of dynamic changes in various parts of the rotating system and feed them to a processing means that generates compensating control signals for electrohydrostatic drives . EFFECT: reduced vibration in movably connected vibrating parts of the helicopter structure. 3 n. and 13 z.p. f-ly, 5 ill.
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The invention relates to the field of aviation, in particular to the structures of vertical takeoff and landing aircraft. The tiltrotor comprises a fuselage, a stabilizer, a keel located in the tail section of the fuselage, consoles installed near the center of gravity on both sides of the fuselage, fairings, columns, rotors with blades, swashplates, swashplate controls. The consoles are connected to the fuselage by means of hinges, providing the ability to change the angle of rotation in the range from 100 to -10 degrees relative to the horizon independently of each other. The speakers are rigidly connected to the consoles and covered with fairings. The rotors contain blades with jet engines connected to the columns by means of torsion bars mounted on freely rotating shafts of the columns in bearings. Jet engines are located in the console part of the blades and have nozzles oriented towards the trailing edge of the blades. EFFECT: ability to control tiltrotor exclusively by means of swashplates. 21 w.p. f-ly, 4 ill., 1 tab.
A tiltrotor that is capable of level flight like an airplane, while still being able to hover, take off and land vertically like a helicopter. For a long time, designers have been embarrassed by their attractive prospect, to increase speed compared to a helicopter and, at the same time, not to depend on the availability of airfields like an airplane.
And by the end of the 1920s of the last century, design thought began to boil.
The work unfolded in two directions - the creation of devices with rotary propellers and devices with a rotary wing.
In particular, in 1922, the American inventor Henry Berliner, based on the Newport 23 fighter airframe, built an aircraft equipped with two counter-rotating propellers and one variable-pitch propeller with a diameter of 30 cm. The propellers were driven by a Bentley BR-rotary engine. 2 with a capacity of 220 liters. with., installed in the forward fuselage. The large propellers provided a helicopter-like flight, and the small one allowed the pilot to slightly tilt the nose of the machine - as a result of this, the large propellers also tilted slightly forward and ensured an airplane-like flight. Later, the designer converted the biplane into a triplane (this device is known under the designation "Model 1924" and also differs in the location of tilting propellers in the middle part of the triplane box), but he was never able to provide an acceptable lift - the device rose a maximum of 15 feet (4 .6 meters).
Biplane designed by American Henry Berliner
Based on the experience gained, G. Berliner in 1925 built an apparatus that generally resembled a biplane, but equipped with two large-diameter propellers installed in the wing tips and partially tilted forward, thus allowing it to fly both in a helicopter and and by plane. Berliner managed to develop a flight speed of about 40 miles per hour (about 70 km / h) on his apparatus, but he did not succeed in significantly increasing the flight altitude. However, according to eyewitnesses, the propellers did not lean forward completely - only at a certain angle, which allowed the device to move forward, and therefore aviation historians call this device a “helicopter with rotary screws”. In general, the concept of the aircraft of G. Berliner is similar to modern convertiplanes.
On September 16, 1930, George Leberger, who lived in County County, New Jersey, received US patent No. 1775861 for an aircraft project, which can be considered the first version of a tiltrotor, the ancestor of this family. The device, called in the patent simply and uncomplicatedly “flying machine” (“Flying Machine”), was equipped with two coaxial propellers of different diameters installed above the fuselage in the nose, which could be installed in vertical (helicopter) or horizontal (airplane) planes.
However, he did not go further than a patent. As well as the British aircraft designer Leslie Baines, a well-known glider designer who designed the Singapore and Calcutta flying boats by order of the Short company in the 1920s and is the author of the first patent for an aircraft with a variable sweep wing (1949). In 1938, he received a patent for the so-called "helicopter", which was an aircraft-type aircraft, on the end parts of the wing of which there were engine nacelles that could be installed vertically - for helicopter flight or horizontally propellers forward - for airplane flight. For the practical implementation of his idea, Baines did not have enough money.
"Helicopter" by Leslie Baines
The situation was more successful with the German aircraft designers. Since 1942, the Focke-Ahgelis specialists have been developing here the Fa 269 mixed design fighter - a tiltrotor with rotary screws. The company was founded on April 27, 1937 by the famous German aircraft designer Heinrich Focke and the German pilot Gerd Akhgelis, no less famous in those years, with the aim of developing and building helicopters and gyroplanes. The most famous of them was the Fw 61, which made its first flight on June 26, 1936 and in subsequent years set a number of records for altitude, speed and flight range for machines of its class.
The Fa 269 was developed under the direction of engineer Paul Klage with the aim of integrating the advantages of a helicopter capable of taking off and landing vertically, and an aircraft with higher speed and better fuel efficiency in one device. At the same time, work on this topic was not started from scratch. Back in 1938, engineer Simon, at the direction of Adolf Rohrbach, technical director of the Weser Flygzugbau G. m.b.H. in Lemwerder, near Bremen, began the design of a single-seat aircraft with a rotary wing, designated WP 1003/1. Rohrbach, an engineer by education, since 1933 independently studied the possibilities of creating a tiltrotor, and having received the plant and its design bureau at his disposal, he decided to try to put this idea into practice.
WP 1003 / 1 was a monoplane with an average location of a trapezoidal rotary wing - the outer halves of its consoles turned with pulling propellers with a diameter of 4 meters located in their end parts. The propellers could turn down almost 90 degrees. A 900 hp engine housed in the fuselage. With. was supposed to provide the tiltrotor with a maximum horizontal flight speed of about 650 km / h. The pilot's cockpit was shifted forward and had a sufficiently large area of glazing, which provided a good overview for the pilot.
As for the Fa 269, it was structurally a mid-wing monoplane with a small sweep along the leading edge, in the middle part of which were located two pushing three-blade propellers of very large diameter. If it was necessary to switch from airplane mode to helicopter mode, the propellers turned down at an angle of up to 85 degrees, this was mainly supposed to be done during takeoff and landing. BMW 801 air-cooled radial engine with 1800 hp. With. located in the fuselage, behind the cockpit, and worked on propellers using a special transmission. Moreover, the developers were required to use the main landing gear with long struts on the machine, as well as the tail landing gear with a sufficiently high strut that retracted into the fuselage - in order to avoid damage to the propellers on the ground (runway). The crew - one, according to other sources, two people, was located in a fairly spacious cockpit, shifted forward and had a large glass area, including for a better downward-forward view. Armament - two 30-mm guns MK 103 or MK 108 - were located on the sides of the cabin. It also provided for the possibility of placing a 20-mm gun MG 151/20 in a special gondola under the fuselage. The avionics included radio stations FuG 17 and FuG 25 a, the possibility of installing a radio altimeter was studied - to perform a "blind" flight.
The terms of reference for the new “wonder weapon” were issued by the German Ministry of Aviation to the Focke-Ahgelis company back in 1941. The military needed a single-seat "local defense fighter". However, according to other sources, the work was purely initiative in nature, but was favorably received by the military. The development of the tiltrotor was completed in 1942, a scale model was blown in a wind tunnel, and a full-size model was soon built. The main advantage of the tiltrotor fighter was considered unpretentious in terms of basing and prompt action against Allied bomber aircraft, which had already gotten to the German military-political leadership. However, after the mock-up and all project documentation were destroyed during the next allied air raid on the night of June 3-4, 1942, work on the program began to fade, and in 1944 the project was completely closed. The main reasons for the failure are the lack of funds and time (according to the calculations of the specialists of the developer company, a prototype at such a pace could be built no earlier than 1947), as well as the lack of special gearboxes, drives, various mechanisms and equipment required for the machine. It remains to be added that in 1955 an article was published in the British magazine Flight, which reported: in the United States, Professor Fokke received a patent for a tiltrotor project "developed in the interests of the Brazilian government." More detailed information on this project was not contained.
The United States steps in
Work in the field of convertible aircraft did not go unnoticed by the opponents of the Third Reich, especially since the bulk of the documents on German developments and the surviving engineers and designers fell into the hands of the Americans and the British - the former weapons creators did not seek to surrender to the Russians. Moreover, they began to adopt the experience of German engineers in the West in the early 1940s.
Among those who decided to take advantage of the experience of German helicopter builders were Dr. Wynn Lawrence Le Page and Haviland Hull Platt, founders of the Platt-Le Page Aircraft Company of Addystone, Pennsylvania. Taking the design of the German Fw-61 helicopter as a basis, the Americans in 1941 designed the XR-1 A twin-rotor helicopter. The latter, in turn, served as a reference point for the creation of an outwardly similar tiltrotor with a take-off weight of 24 tons. The fundamental difference was that its propellers could turn, leaning forward, and provide the car with an airplane-like flight. Moreover, despite the fact that this tiltrotor was not implemented in hardware or at least in a full-size layout (it did not even have its own name), the work was not in vain - on December 15, 1955, H. X. Platt received a US patent for No. 2702168 .
Convertiplane Le Page - Platte
The next attempt to successfully "cross" a helicopter and an airplane was made in early 1947 by specialists from the Transcendental Aircraft Corporation of Newcastle, Delaware. This time, aircraft designers managed to create a truly efficient aircraft, which managed to take to the air and, on the whole, confirmed the correctness of the chosen technical solutions.
This project was initiated and driven by the founders of Transcendental, Mario A. Guerieri and Robert L. Lichten, who previously worked together at the Kellett Aircraft Company. Moreover, Lichten had previously worked with American helicopter designers - Le Page and Platt mentioned above - and became an active supporter of the tiltrotor concept, and Guerieri joined him while working at Kellett. Together they conducted a significant amount of research to find out how effectively the main rotor used in helicopters can be used in the version of the "aircraft" propeller.
The results obtained in the course of these works added to Lichten and Guerieri the confidence that they are on the right track and their idea is not so fantastic. Like-minded people decided that now they need to independently develop, build and lift into the air, proving its ability to fly, a small single-seat experimental tiltrotor, designated "Model 1-G".
The world's first flying tiltrotor "Model 1-G"
A distinctive feature of the machine, which had a maximum length of 7.93 meters and a takeoff weight of about 800 kg, was the presence of only one piston engine - it was located inside the fuselage and worked on both three-blade counter-rotating propellers (screw diameter - 5.18 m) located in end parts of the wing with a span of 6.4 meters.
The maximum power of the Lycoming O-290-A four-cylinder engine, located in the fuselage directly behind the cockpit, reached 160 hp. with., at 3000 rpm. The maximum flight speed in airplane mode is 256 km / h (propellers - no more than 633 rpm), in helicopter mode - 196 km / h (no more than 240 rpm). The transition from one mode to another took no more than 3 minutes, while the screws could rotate within 82 degrees. The fuel supply allowed to be in the air for up to 1.5 hours.
The first tiltrotor built by the company collapsed during ground static tests in 1950, but the second, which is known under the designation "Model 1-G", was initially considered by the developer only as a ground test vehicle and only after receiving a government contract was modified for the program. flight tests.
The first tiltrotor in the world went on its first flight on June 15, 1954, but only five months later its creators risked switching from one flight mode to another. By that time, both founders of the company had already left it. Lichten in 1948, and Guerieri in September 1952, sold his share to William E. Coby, who worked as a diagnostics specialist for the Kellett Aircraft Corporation. Moreover, Kobe managed to secure financial support - albeit small - from the US Department of Defense. In fiscal year 1952, the Army and Air Force ministries signed a contract with the company, according to which customers were to receive all the results of flight tests of the new machine. A similar contract was signed with the US Air Force the following year, 1953.
However, having made a little more than 100 flights with a total duration of 60 hours, during which, however, a complete transition to the airplane mode was never completed, on July 20, 1955, the tiltrotor lost control and crashed while flying in the airplane mode. in the waters of the Chesapeake Bay. The accident occurred near the coast, in shallow water, and the pilot managed to escape. The device, of course, had to be written off.
Nevertheless, the possibility of creating an aircraft of a new class was confirmed in practice, and the company began building the second prototype tiltrotor - Model 2. It was already a two-seater, with pilots landing side by side, had a take-off weight of 1020 kg, a shorter fuselage by 1.2 meters and a wing span that was 0.3 meters smaller. It was powered by a One Lycoming O-435-23 six-cylinder engine producing 250 hp. with., and the payload reached 304 kg.
Convertiplane "Model 2"
However, the US Air Force pulled out of the project. The preference for the military was given to the alternative apparatus XV-3, developed by Bell, and it was impossible to fully implement the test program at its own expense. As a result, the tiltrotor "Model 2" managed to make only a few short-term flights in helicopter mode. The program was finally closed in 1957.
Famous "Pentecostals"
During the 1950s, a number of tiltrotor projects were developed in some other companies, but the vast majority of them did not even take to the air. However, there were quite remarkable projects among this host of developments, which are worth briefly dwelling on.
In the 1940s and 1950s, the US military showed an active interest in vertical or short takeoff and landing aircraft, thanks in part to information about equally active work being carried out in the Third Reich. One of the companies engaged in work in this area was Vertol Erkraft (formerly Piasecki), which developed the Model 76 aircraft on its own initiative. In 1960, this company was acquired by the Boeing concern and became its helicopter division Boeing Vertol.
A distinctive feature of the new machine was that it was the first in the world to successfully implement the technical idea of a rotary wing. Previously, such machines were called rotorcraft, but they can also be classified as "tiltiplanes". Structurally, the device, which later received the name VZ-2, was a monoplane with a high wing installed in its central part, with an open truss fuselage and a tricycle landing gear with a nose strut and a tail wheel. It had a cockpit with a spherical canopy from a Bell 47 helicopter, behind which was an Avco Lycoming YT53-L-1 gas turbine engine and transmission.
Convertiplane VZ-2
The wing, rectangular in plan, had an all-metal structure and was attached to the fuselage on hinges and, under the action of hydraulic power cylinders, could rotate 90 degrees. Take-off in a helicopter was carried out by turning the wing and three-blade propellers vertically upwards, and after reaching a safe height, the pilot returned it to its normal position - the device switched to airplane mode. The tail unit is T-shaped, with a large keel. At the same time, for more effective control when flying at low speeds, additional propellers of small diameter were placed in the tail section of the VZ-2.
Experimental car, sir. No. 56–6943, flown in April 1957. The first successful transition from one mode to another - in horizontal flight - was made on July 23, 1958. Even before that, the development company signed a contract with the US Army and Navy ministries, which allocated 850 thousand dollars for the completion of the device, which received the new designation VZ-2 A. Flight tests were initially carried out by the developer company, together with specialists from the US Army and the NASA aerospace agency, but in the 1960s the project was completely transferred to the latter. The S.P. Langley Research Center operated the VZ-2A until 1965. During the operation of the apparatus, about 450 flights and 34 complete transitions from one mode to another were performed. The device is currently on display at the Smithsonian Institution.
Convertiplane VZ-2
Another interesting project was the tiltrotor, developed in 1959 in cooperation with Vertol specialists and the NASA agency. It did not receive any name of its own and is simply referred to as a device with a rotary wing developed by Vertol - NASA (Vertol-NASA Tilt-Wing). Its distinctive feature was a rotary wing, on which there were six propellers, which were supposed to be driven by a 1000 hp motor. with., as well as double-slotted ailerons, which occupied up to 60% of the length of the trailing edge of the wing. Work on the project, however, did not go further than blowing a scale model in a wind tunnel.
A completely different concept of "merging an airplane and a helicopter" was worked out by American aircraft designers on the tiltrotor VZ-4. Its development was carried out in the second half of the 1950s by the Doak Aircraft Company of Torrance, California. This apparatus had rotary propellers in the annular nozzles (channels). The reason for choosing this design option was simple - the president of the development company, Edmond R. Doak, was engaged in work in the field of propellers located in annular channels.
VZ-4 at the US Army Museum, Fort Estis
E. R. Doak first sent his proposal to the military in 1950, but it was not until April 10, 1956 that the US Department of the Army, represented by the Transportation Engineering Research Command, signed a contract with him. The following year, the company began active work on the device, which at first received the in-house designation "Doak 16". Its first flight took place on February 25, 1958 (serial number 56–9642). Subsequently, the tiltrotor was renamed the VZ-4 DA, structurally it was a small experimental medium wing with a pilot's cabin with a tandem landing of two people (pilot and observer), with a traditional tail and a fixed tricycle landing gear with a nose strut. The tiltrotor fuselage was made of welded pipes, the skin from the nose to the cockpit was composite (molded fiberglass), and from the cockpit to the tail it was aluminum. Cantilever wing and tail - all-metal.
The main distinguishing feature of the Doak 16, equipped with one Lycoming T53-L-1 turboshaft engine with an 825 horsepower. with., there was the presence of rotary propellers in the annular channels (nozzles) located in the end parts of the wing planes. The propellers could turn forward 90 degrees to perform horizontal flight, and also deviate back 2 degrees from the vertical - when operating in the "helicopter" mode.
In order to minimize the cost of designing and building a tiltrotor, Doak decided to make the most of the developments of other aircraft manufacturers and structural elements from other aircraft. In particular, the landing gear was borrowed from the Cessna-182, the crew seats - from the F-51 Mustang, the drives for turning the propellers in the annular channels - from the electric motors of the flap drive of the training T-33, and the rudder - from an earlier aircraft development "Doak".
The tiltrotor "Doak 16" was built in a single copy (serial number 56–9642). Its estimated empty weight was 900 kg, and the maximum take-off during vertical take-off was 1170 kg, however, in the process of finalizing the machine, these figures increased to 1037 kg and 1443 kg, respectively. The maximum speed, according to calculations, was to be at least 370 km / h in horizontal flight, the rate of climb at sea level was 30 m / s, the service ceiling was 1830 m, the flight duration was about 1 hour, and the maximum flight range was 370 km.
Ground tests of "Doak 16" took place on the territory of Torrance Municipal Airport in February 1958, 32 hours on the stand and 18 hours of "tethered approaches" and taxi tests. On February 25, the first free flight was made. In June, the tests in Torrance were completed, and the tiltrotor underwent a thorough study, after which it was transferred to Edwards Air Force Base in October, where it underwent a 50-hour test, in which the transition from one mode to another was repeatedly performed - including number at an altitude of 1830 meters.
After the completion of the tests, the US Army in September 1959 accepted the tiltrotor, assigning it the designation VZ-4, and transferred it to the Langley Research Center, owned by NASA, for new tests. In the course of the latter, not only the advantages, but also a number of disadvantages of this scheme were revealed. One of the most significant was the tendency of the device to turn up its nose during the transition between helicopter and airplane modes. It turned out to be worse than expectations and take-off and landing characteristics. During the tests, the tiltrotor was able to develop a speed of 370 km / h, the maximum rate of climb was 20 m / s, and the flight range was 370 km.
In the late 1960s, the development company entered a period of financial failure and sold the rights and all the technical documentation for the VZ-4 tiltrotor company Douglas Aircraft, located nearby, in Long Beach. But this did not help either - in 1961, the Doak company ceased to exist. Douglas, meanwhile, completed a preliminary study of the modernization of the unexpectedly received tiltrotor, including the installation of a more powerful engine, and in 1961 sent a proposal to the US Army command. However, there was no answer. The tiltrotor itself was operated at the Langley Center until August 1972 and then transferred to the US Army Transportation Service Museum at Fort Estis, near Newport News, where it is today.
Another American experimental convertoplane with a rotary wing was the X-18, developed by Hiller under a contract with the US Air Force dated February 1957. The contract, worth 4 million dollars, provided for the development, testing of a tiltrotor, as well as the construction of 10 machines. The company also managed to get a contract for similar work from the US Navy - the admirals needed a tiltrotor capable of taking cargo weighing up to 4 tons. During the construction process, individual structural elements from other aircraft were actively used. In particular, the fuselage was a slightly modified fuselage from Chase's XC-122C, while other elements were from Conware's R3 Y Tradewind military flying boat.
X-18 convertoplanes
The X-18 had a rectangular fuselage with a high wing of small span, in the middle part of which two powerful 5500 hp winglets were installed. With. Allison T40-A-14 turboprop engines with Curtis-Wright three-bladed counter-rotating turbo-electric propellers (diameter 4.8 meters). Moreover, during takeoff in a helicopter, the entire wing turned along with the engines (around its longitudinal axis at an angle of up to 90 degrees), although takeoff in an airplane was used for takeoff with a maximum payload. In addition, an additional Westinghouse J-34-WE turbojet engine with a thrust of 1530 kgf (15.1 kN) was located in the tail section of the car, the jet stream of which could deviate in a vertical plane, which improved the controllability of the car at low speeds.
In 1958, the first, and as it turned out, the only prototype was built, which went through an intensive cycle of ground tests and in 1959 was transferred to the Langley Research Center, where on November 24, 1959 it performed its first free flight. Before the completion of flight tests in July 1961, the tiltrotor managed to make 20 flights. The main reason for the completion of the test and the subsequent closure of the program was a malfunction in the propeller pitch change mechanism that occurred on the last flight, and the fact that the engines "were not interconnected." However, he still made it possible to collect a sufficient amount of data necessary for the construction of a heavier tiltrotor - the four-engine XC-142. During one of the ground tests - after the completion of the flights, the X-18 tiltrotor was destroyed and ended its days in a landfill.
XC-142A at the National Museum of the United States Air Force
As for the XC-142, it was developed jointly with the Vought and Ryan companies in the first half of the 1960s. It was equipped with four General Electric T64-GE-1 engines with a capacity of 2850 hp each. with., which rotated fiberglass propellers of the Hamilton Standard brand with a diameter of 4.7 meters. The tiltrotor, after modification, received the designation XC-142 A, was intended to carry up to 3500 kg of cargo or paratrooper units. A total of 5 vehicles were built, the first one was flown on September 29, 1964, and on January 11, 1965, the transition between modes was made in flight for the first time: vertical takeoff, horizontal flight and vertical landing.
The first XC-142A was handed over to the US Air Force in July 1965. During subsequent flight tests, five built prototypes flew 420 hours (488 flights, 39 military and civilian pilots were involved), including takeoffs / landings on the deck of ships, participation in search and rescue exercises, dropping paratroopers and dropping cargo at low altitude. The tiltrotor had a maximum takeoff weight of 20227 kg, an empty weight of 10270 kg, and could take a payload of 3336 kg (32 paratroopers in full gear or 24 stretcher wounded with 4 escorts).
During testing and trial operation, four convertiplanes were broken. The US Department of the Air Force in 1966 tentatively announced its intention to purchase a batch of serial S-142 B convertiplanes, but it did not come to a contract, and the remaining copy (plant No. 65-5924) was transferred to NASA, where it was operated from May 1966 to May 1970 of the year . A civilian version was proposed, the Downtowner, designed to carry 40-50 passengers at a speed of 470 km / h with only two engines running. However, this idea was also not implemented.
Simultaneously with the work on the XC-142 A, another company, Curtis-Wright, carried out work on the X-100 tiltrotor, a distinctive feature of which was the presence of two rotors. The single-seat X-100, as well as a number of other convertiplanes, was a relatively inexpensive experimental device designed to assess the technical feasibility of creating and effectively operating an aircraft with rotary propellers.
X-100 tiltrotor
The X-100 had one Lycoming YT53-L-1 turboprop engine with an 825 horsepower. s., which was located in the fuselage and set in motion both rotary screws, while balancing in hover mode and when flying at low speeds was provided using a controlled jet nozzle located in the tail section of the machine. The main task in the framework of the X-100 program was to develop a tiltrotor scheme with rotary screws, which was necessary for the development and construction of a more important device of this type, first designated M-100, and then X-19. It was also necessary to work out the issues of creating fiberglass propeller blades.
Work on the X-100 began in February 1958, and in October of the same year, intensive blowdowns in the wind tunnel began. On September 12, 1959, he made the first hover, and on April 13, 1960, the first transition from one regime to another was completed. However, in subsequent tests it turned out that the flight characteristics of the tiltrotor are not entirely satisfactory, and the balancing and control system at low flight speeds does not meet the requirements.
On the other hand, the feasibility of the X-100 concept was fully proven, which prompted the developers to move on to work on the heavier X-19 tiltrotor. On July 21, 1960, testing of the X-100 was completed and the vehicle was transferred to the NASA Langley Research Center, and then was donated to the National Air and Space Museum at the Smithsonian Institution.
X-19 tiltrotor
The M-200 tiltrotor (from Model 200) had an "airplane" fuselage and two small-span tandem wings, at the tips of which there were rotary propellers with a diameter of 3.96 meters each, driven by two Lycoming T55-L-5 turboshaft engines with a capacity of 2620 l. With. In case of failure of one engine, the cross transmission provided the drive of all four propellers from the other. The US Department of Defense considered the possibility of using this tiltrotor in the role of reconnaissance and transport. The car was flown on June 26, 1964, after which it was transferred for further testing to the US Air Force. She was given the new designation X-19. However, as in the case of the X-100, the performance obtained was worse than expected. August 25, 1965 X-19 crashed in the next flight.
"Magnificent" Troika "from the company" Bell "
One of the decisive, turning point projects in the history of tiltrotor construction was the XV-3, developed by Bell Aircraft. Her first experience in this area was the Envelope-O-Plain Model 50 tiltrotor developed on her own initiative, followed by a whole series of projects, most of which, however, did not advance further than the drawing board.
However, then her finest hour came - the company became the favorite in the tender announced in 1950 by the US Army and Air Force commands as part of the Convertible Aircraft Program. The following year, the company received a contract to build and conduct extensive testing of two machines of the XV-3 Convertiplane type.
Restored tiltrotor XV-3
The XV-3 was a small tiltrotor with a takeoff weight of 2177 kg, a length of 9.25 meters and a wingspan of 9.55 meters. The crew consisted of two pilots, arranged according to the "tandem" scheme. The power of the engine located in the fuselage was 450 liters. With. The machine had two three-bladed propellers, which were installed in gondolas located at the ends of the wing - on special rotary devices. The translation of the screws from a vertical to a horizontal position was carried out mechanically and took no more than 10 seconds.
Ground tests of the machine started in early 1955 at the company's plant in Hurst, Texas. Then the turn came to flight tests - the first car (Ship 1) took off on August 11, 1955, but during the 18th flight it suffered a minor accident. Fortunately, there were no casualties then. The first time the regime change was performed on July 11, 1956, but already on October 25, during another attempt, an accident occurred - the car crashed, and the pilot was seriously injured.
During the tests, it quickly became clear that the car had a lot of flaws. Partially they were eliminated on the second instance (Ship 2). On December 18, 1958, the transition from one flight mode to another was successfully carried out on it, after which the car was handed over for testing by the Air Force and NASA, during which 11 pilots flew the XV-3 for a total of 125 hours in 250 flights, performing 110 "full transitions". In addition, various takeoff and landing options were worked out. So, for example, when taking off with a short takeoff run, the car at a speed of about 57 km / h rose into the air with a run of only 61 meters (the propellers were installed at an angle of 80 degrees to the horizon). The test pilots managed to reach an altitude of 3750 m on the XV-3 and develop a speed of 213 km / h, as well as work out the landing in autorotation mode.
Ultimately, the construction and testing of two XV-3s was an important milestone in the global aircraft industry. However, the success was only partial: the very possibility of building a tiltrotor was proved, but, in fact, it could not represent practical value.
Convertiplane XV-3 during a test flight
The further fate of the tiltrotor is very interesting. At the end of 1966, the remaining XV-3, head. No. 54–148, was moved to an aircraft storage facility at Davis-Monthan Air Force Base in Tucson, Arizona, and was forgotten for almost two decades. It was not until 1984 that specialists from the XV-15 tiltrotor design group, developed by Bell, tracked it down at the US Army Aviation Museum in Fort Rucker, Alabama. The device was restored in December 1986, after which it was dismantled and mothballed in a covered hangar, where it remained for another two decades. Finally, on January 22, 2004, the XV-3 was moved to Bell's Plant 6 in Arlington, Texas, and the factory's specialists began to restore it under the guidance of former XV-3 program engineer Charles Davis. Two years later, the XV-3 took its place on display at the National Museum of the US Air Force in Dayton, Ohio, where it remains to this day.
Convertiplanes in the USSR
Convertoplane Mi-30 in level flight
Soviet designers, realistically assessing the large number of difficulties associated with the development of a convertible apparatus, were skeptical about various “dubious” projects for quite a long time, but nevertheless, work on tiltrotor projects was also in the USSR.
In particular, in KB Mil. Mi-30 is a Soviet project of a multi-purpose tiltrotor, the development of which began in 1972 at the Moscow Helicopters. M. L. Mil, the project leader was M. N. Tishchenko. Inside the design bureau, this design scheme had its own designation "rotorplane". The main task in creating the Mi-30 was to ensure such parameters as range and flight speed, which would surpass the performance of helicopters of a similar class.
The Mi-30 convertoplane was considered by the creators as a promising replacement for the Mi-8 multi-purpose helicopter. In the original project, the Mi-30 was designed to carry 2 tons of cargo and 19 passengers, but later the vehicle's carrying capacity was increased to 3-5 tons, and the passenger capacity was increased to 32 people.
In 1972, the designers of the MVZ them. M. L. Mil, on their own initiative, created a project proposal for a transport and passenger tiltrotor, called the Mi-30. According to the terminology available in the USSR, it was originally called a helicopter-aircraft, but later the Milevites came up with their own designation for it - a propeller plane. The main task in the design of the Mi-30 was to ensure flight performance, primarily the range and flight speed. Initially, it was supposed to carry up to 2 tons of cargo and 19 troops.
As a power plant for the new machine, it was planned to use 2 TV3-117 engines located above the cargo compartment, the engines were supposed to drive 2 main-pull propellers with a diameter of 11 m each using a transmission. The screws were located at the ends of the wing consoles. The estimated flight speed of the Mi-30 was estimated at 500-600 km / h, and the flight range was to be 800 km. The take-off weight of the machine is 10.6 tons. The Milevites were able to involve TsAGI in the research within the framework of this program. Soon, by joint efforts, the construction of an aerodynamic stand was started to test the propeller model. At the same time, the designers of the Mil Design Bureau created an experimental flying radio-controlled model of a rotorcraft in order to study the transitional modes, controllability and stability of the device in flight.
During the development process, the customer wanted to increase the carrying capacity of the Mi-30 to 3-5 tons, and increase the passenger capacity to 32 people. As a result, the propeller project was redesigned to use 3 forced TV3-117F engines. At the same time, the diameter of the load-bearing propellers grew to 12.5 m, and the take-off weight of the Mi-30 to 15.5 tons. conducted thorough analytical studies of the problems of structural dynamics, aeroelasticity, flight dynamics and aerodynamics characteristic of convertible vehicles.
Taking into account the depth of the project study, the existing many years of factory experience in solving difficult problems, the Commission of the Presidium of the Council of Ministers of the USSR on armaments in August 1981 issued a decree on the creation of the Mi-30 helicopter with a convertible carrier system (rotorplane). The created technical proposal was submitted for consideration by the customer and the MAP institutes. The military approved the creation of the machine, but demanded that more powerful engines be put on the rotorcraft - 2 D-136 engines, the estimated weight of the tiltrotor increased to 30 tons. 
As a result, the creation of the Mi-30 was included in the state armament program for 1986-1995. But the collapse of the USSR and the resulting economic difficulties put an end to the Mi-30 propeller plane and he never got out of the stage of analytical and design research. In the last year of the existence of the USSR, OKB specialists designed 3 different propeller planes: Mi-30S, Mi-30D and Mi-30L, which had a carrying capacity of 3.2, 2.5 and 0.95 tons, respectively, and a passenger capacity of 21, 11 and 7 people. The first 2 convertiplanes had a maximum takeoff weight of 13 tons. It was planned to equip them with power plants from 2 TV7-117 engines, and the third Mi-30L (weighing 3.75 tons) with a power plant from 2 AL-34s. Work was also carried out on the creation of combat options.
In the early 1990s, the possibility of participation of the Moscow Helicopter Plant them. M. L. Mil in European projects and programs, including Eurofar and Evrika, which were aimed at creating convertiplanes similar to the Mi-30. But at that time in Russia there were no conditions for organizing such joint projects.
Convertiplanes are special aircraft that combine the capabilities of a helicopter and an airplane. They are machines with rotary propellers (most often screw propellers), which work as lifting during takeoff and landing, and in flight they begin to work as pulling. In this case, the lifting force necessary for horizontal flight is provided by an aircraft-type wing. Most often, tiltrotor engines turn with the propellers, but on some, only the propellers are turned.
Functionally, this design is close to a vertical takeoff and landing aircraft (VTOL), but tiltrotor aircraft are usually referred to as rotary-wing aircraft due to the design features of the propellers. Convertiplanes use lightly loaded low-speed propellers, close to helicopter ones and allowing the device to fly in helicopter mode - with a small angle of rotation of the propellers. The tiltrotor's large wing-span propellers help it in vertical takeoff, but in level flight they become less efficient than the smaller diameter propellers of conventional aircraft.
As already reported, Russian and American scientists are working on the creation of a new type of aircraft - a tiltrotor. However, such a device has already been created and its limited use has already begun.
What is this machine?
A tiltrotor is a mixture of an airplane and a helicopter. An aircraft that can land and take off vertically, and then, thanks to the rotation of the propellers, continue horizontal flight in an airplane way.
Traditionally, tiltrotor aircraft are classified as propeller-driven vehicles in order to somehow distinguish them from vertical takeoff and landing aircraft. There are several types of convertiplanes. For some, when changing the flight mode, the entire wing turns at once, for others, the nacelles with engines and propellers, and for others, only the propellers themselves.
The benefits of this concept are obvious:
Taking off and landing on a patch is a valuable capability for both military and civilian aircraft;
In the air, the tiltrotor develops a greater speed than a helicopter and is ahead of its rotary-wing counterparts in terms of flight range.
But there are also disadvantages:
The speed and flight range, although greater than that of helicopters, are inferior to aircraft performance. Propellers designed to provide lift on takeoff lose their effectiveness in level flight;
The structure itself is heavier. For aviation, situations are not uncommon when, when creating a new machine, the struggle is for every kilogram, and the engine turning mechanism weighs decently;
In addition, this is an additional critical node that can also break;
And most importantly - the complexity of piloting. Convertiplanes require specially trained, experienced high-class pilots with skills in piloting both airplanes and helicopters. "The Last Inch" cannot be played on a tiltrotor.
Thus, universal machines turn out to be more efficient than the original ones in a rather narrow segment of tasks. For example, if the point where the cargo needs to be delivered is located outside the range of helicopters, and the equipment of the runway is not possible.
The United States Department of Defense considered that such situations would happen quite often, and ordered more than one and a half hundred Bell V-22 Osprey convertibles for the needs of the Marine Corps for this case. The car turned out to be quite expensive (about $116 million) and not very reliable.
In just ten years of operation, 6 disasters occurred that claimed the lives of seven people. The latest occurred in 2016, when an Osprey carrying 22 people made a hard landing in Hawaii on May 17. And this is not counting the fifteen-year period of fine-tuning and testing, during which 30 people died as a result of accidents of this super-complex machine.
But the United States has the right to be proud of the unique equipment that is not in service with other armies of the planet.
But perhaps this situation will end after a while. Recently, the Russian concern "Helicopters of Russia" received information that work on the creation of a domestic tiltrotor is already underway. Moreover, it was not just anyone who said this, but the director of the company
Andrey Shibitov:
"Together with our partners, we are working on a technology that is completely new for Russia for a tiltrotor with a hybrid power plant. We plan that such a design scheme will allow us to confidently reach speeds of up to 500 kilometers per hour."
It is supposed to create first an unmanned vehicle with a take-off weight of about 300 kilograms. A small copy is needed solely for demonstration purposes in order to assess the prospects of the project in advance.
Then the same one is planned, but already for two tons. This machine can already be used as a separate unit with its own range of tasks befitting a heavy drone.
In the 30s of the last century, Soviet aircraft designers worked out various options for building a tiltrotor. But this matter did not move further than R&D. The designer Boris Yuriev was an enthusiast for the development of this type of aircraft.
In 1934, he proposed the design of the Sokol fighter, which was supposed to have a rotary wing and a pair of propellers in gondolas. However, neither Sokol nor other Yuriev's helicopter-aeroplanes reached the stage of flight tests - the level of technology at that time was still insufficient.
Before the outbreak of World War II, research was also carried out in Germany. All of them stopped at the drawing stage: the Wesserflug P.1003 tiltrotor, the Wunderwaffe (“wonder weapon”) Fa-269 of the Focke and Ahgelis company, as well as the designs of the Heinkel and Focke-Wulf companies.
The English convertible Fairey Rotodyne helicopter can also be attributed to convertiplanes, capable of using two pulling turboprop engines to switch to the autorotation mode of the main rotor (rotation with the help of an oncoming air flow, like in a windmill), when taking off, it works like a helicopter. In 1958, this device was presented at the Farnborough Air Show. He developed a record speed for rotorcraft of 400 km / h.
In the 50s, a prototype of the tiltrotor XYF-1 Pogo was built. In 1954, the XFY-1 made its first level flight and subsequent vertical landing.
In 1972, the Mil Design Bureau took up the matter seriously, starting the development of the Mi-30 tiltrotor with two rotary screws that change position along with the engines located in the nacelles.
After positive results were achieved - the carrying capacity of the designed machine was 5 tons, and the number of paratroopers transported was 32 - the production and testing of prototypes was planned for 1986-1995. However, this project, like dozens of others across the country, was closed due to the restructuring and subsequent collapse of the industry.
Interesting is the only country that is armed with convertiplanes, and the American Bell V-22 Osprey ("Oscopa") is the only mass-produced tiltrotor in the world.
The creation of the V-22 Osprey began in the 1980s after the failure of Operation Eagle Claw (an attempt to free hostages in Iran on April 24, 1980), when it became necessary to create a faster alternative to the helicopter. At that time, vertical takeoff aircraft already existed, but they had a number of disadvantages associated with instability during takeoff, difficulty in piloting, worse payload and flight range compared to conventional aircraft. Also, during takeoff, a hot jet of exhaust gases from jet engines caused erosion of the coating of the runways.
Flight tests of the new aircraft began on March 19, 1989. Already in September, Osprey successfully demonstrated the change in flight from vertical to horizontal. In December 1990, the convertiplane made its first landing on the deck of the aircraft carrier USS Wasp.
It was decided to equip the Marine Corps and the Special Operations Forces with such machines. The Navy entered into a contract to purchase four V-22s and upgrade two existing prototypes to be lighter and cheaper. The price of one device was $71 million.
Now in Russia they have decided to return to the idea of creating a “helicopter aircraft”. But so far this is happening at the level of research conducted in Russian universities. Which, nevertheless, can give real results. Thus, at Ukhta University, with the participation of MIPT and TsAGI, the research work “Determining the rational parameters of a new vehicle (tiltrotor) for the northern regions and offshore fields” was carried out.
As a result of this research, it is quite possible to build a tiltrotor with a flight range of 2000 km with 14 passengers on board, including two pilots. The payload of the machine is 3 tons. But, of course, to bring the case to a victorious end, solid funding is required. At the same time, potential investors are well aware that, based on world experience, this is an extremely protracted and risky business.
The Russian Helicopters holding plans to create by 2019 a prototype of the first electric tiltrotor in the Russian Federation weighing 1.5 tons. We are talking about the unmanned aerial vehicle VRT30, which was presented at the MAKS-2017 forum. A tiltrotor - a hybrid of an airplane and a helicopter - is a very expensive and high-tech machine. At the moment, only convertiplanes are mass-produced and used for military purposes. There are no such aircraft in the Russian army, despite the fact that the pioneer in the development of these miracle machines was the Soviet designer Boris Yuryev. What tasks are tiltrotors capable of performing and will they appear in service with the RF Armed Forces.
Projects to create a Russian tiltrotor are beginning to take on real features. The VR-Technologies design bureau (part of the Russian Helicopters holding company) plans to present a prototype of the first electric unmanned tiltrotor VRT30 in two years.
The layout of the future device was presented at the MAKS-2017 aerospace show, which was held in July 2017. A tiltrotor with a take-off weight of 1.5 tons will be able to develop high speed and take to the air without acceleration along the runway.
“Today, together with our partners from SuperOx, we are developing a new flying tiltrotor laboratory, the on-board cable network of which will use high-temperature superconductivity technologies, which will positively affect the weight and size and flight characteristics of the prototype,” said Andrey, General Director of the Russian Helicopters holding Boginsky.
All Tiltrotors face a specific handling problem that is not common to airplanes. On aircraft moving at a sufficiently high forward speed, the traditional controls (ailerons, rudders, and elevators) are in the airflow. The response of the airflow to the deflection of these controls provides control forces that change the position of the aircraft in space. On convertiplanes, the use of such flight controls is possible only in the horizontal (translational) flight mode, but they turn out to be useless in vertical takeoff and landing modes, as well as hovering (since there is no oncoming flow in these modes).
Therefore, Tiltrotors must have a second control system that is effective at low or zero airspeeds. Depending on the scheme and the power plant of the aircraft, this role can be played by:
jet (jet) control system, which includes nozzles and high-speed valves installed at the wingtips and at other points of the aircraft;
thrust vector control system, consisting of several propellers to create and directly control lift;
control surfaces located in the wake of the main propellers or turbines.
According to its scheme, convertiplanes can be conditionally divided into two main classes, each of which is characterized by its specific problems of transferring and converting the thrust developed by the power plant.
First class - convertiplanes with a horizontal position of the device in takeoff and landing modes. These devices remain in a horizontal position - both in takeoff and landing modes, and in horizontal flight mode. In these convertiplanes, for the implementation of transitional modes such as takeoff, the thrust of propellers, fans or jet engines is used, after which the direction of the thrust vector is changed in such a way that the device begins to perform a normal horizontal flight. In level flight, the lift necessary for the movement of the device is usually created due to the flow around the rather traditional wings. In some of the aircraft in this class, the thrust generating devices deviate to a small angle to ensure level flight. In this position, they also create a significant part of the lift.
The second class - convertiplanes with a vertical position of the apparatus in takeoff and landing modes. This class of aircraft includes convertiplanes that take off and land in a vertical position, and to switch to horizontal flight, make a turn of 90 °. Apparatuses of this class have fundamental shortcomings that make them unsuitable for commercial use. Only a few of this type were built. As a rule, these are single-seat military vehicles such as fighter aircraft or purely experimental models.
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