Military Review

Projects of "rotorcraft" type aircraft. Part I

7
From the Chinese exhibition Airshow China 2012 continue to come new news. Of the latest innovations presented at the salon, the most interesting is the new Chinese project of high-speed helicopter. As can be seen from the design of the rotor-wing machine, which received the code name Avant-Courier, when it was created, the maximum speed of flight was set at the forefront. This is indicated by the “licked” fuselage, the fairings of the rotors of the rotors, as well as two small wings with nacelles and propellers. Until now, only helicopters designed to develop high flight speeds had such an appearance. The appearance of the Chinese Avant-Courier indicates that China has joined the current helicopter race.



The scheme used by the Chinese in the domestic technology is called the term "rotorcraft". This means that the aircraft has a separate rotor holding the machine in the air, and a separate system to create horizontal thrust. The main advantage of this scheme lies in the absence of the need to develop and manufacture a complex screw sleeve with a swashplate. In addition, the horizontal thrust becomes the “responsibility” of the individual system, rather than the rotor, and, as a result, the engine power is spent more efficiently, which allows for much higher flight speeds. All the advantages of the helicopter, such as the possibility of hovering and take-off / landing on small platforms, are fully preserved. Until a certain time, the helicopters competed almost equally with helicopters for the right to become the main class of vertical take-off aircraft, but for a number of reasons - primarily because of the relatively complex transmission - they lost. Nevertheless, the development of rotary-winged aircraft continued, although in number they could not compete with helicopters.

Fairey rotodyne

One of the first projects of the rotary-wing, which had good prospects for practical use, was the English Fairey Rotodyne, created in the mid-fifties. The purpose of this project was the manufacture of a promising multi-purpose (primarily transport) aircraft capable of carrying payloads at a higher speed than the existing helicopters. At the same time, the required apparatus was inferior in speed to the available aircraft, but did not require large areas for take-off and landing. After a brief reflection on the appearance of the future machine, the engineers of the firm “Fairy” recalled the old idea with a separate main and separate pulling screws. As a result of research and development in 1957, the first prototype of the Rotodyne was built. He was something that combines the features of a helicopter and an airplane. A screw pylon was installed at the top of the cigar-shaped fuselage. On the sides of the apparatus were two wings with a nacelle on each. In the rear fuselage provided stabilizer with two keels-washers.



Of particular interest is the rotodine power plant. The device had as many as six engines. The first two of them - turboprop Napier Eland NE1.7 with a capacity of 2800 hp. - were placed in wing nacelles. Through their own gearboxes they rotated the pulling screws. Rotor spinning was carried out by four miniature jet engines (one on each blade) of their own design. On turboprop engines, an air extraction system was installed, which entered the engines on the blades, where it was mixed with fuel. The burnt mixture brought the rotor into rotation. Such a system was quite complex and unusual for aviation technology, however, the use of a jet propeller drive simplified the design of the entire Rotodyne due to the absence of the need for a tail rotor that fights off the reactive moment of the rotor. In addition, in the Rotodine power plant, it was possible to turn off the rotor drive, after which the device could fly like a gyroplane and spend all the engine power on horizontal traction. The resulting Rotodyne rotorcraft had solid dimensions: a rotor diameter of 27,5 meters, a total length of almost 18 meters and a dry weight of 7200 kilograms. Initially, only an option for passenger transportation was developed. The cabin of the device could accommodate up to forty people with luggage. At maximum load, the take-off weight of the Rotodine was a little less than fifteen tons.

6 November 1957, the first prototype of the rotorcraft took to the air. During the first flights “in flight-flying”, the controllability was once again checked: the fact is that the yaw control was carried out not by the tail rotor, which was not, but by a separate change in the pitch of the pulling screws. The first flights showed the viability of such a system. Before the end of the first test phase, the Rotodine reached speeds of 250 km / h and heights of 2100 meters. In this case, all flights took place without disconnecting the rotor engines and without the use of pulling screws. In the spring of 1958, the second stage of testing began, during which the rotorcraft began to switch to autorotation mode and fly using turboprop engines. At the very beginning of the 1959 of the year, Fairey Rotodyne set a speed record for units with a rotor. On a closed 100-kilometer route, it accelerated to 307 km / h. It was almost 80 kilometers per hour faster than the previous record for helicopters. At the same time, calculations showed that without changing the design, Rotodine is able to take the bar in 400 km / h.



Rotodyne was first shown to the public at the Farnborough 1958 air show, where its unusual design immediately attracted much attention. However, in addition to the curious "simple" visitors, potential customers also became interested in them. Even before the end of the test, several major air carriers showed a desire to obtain such equipment, and the Canadian company Okanagan Helicopters (now CHC Helicopters), without waiting for the end of the salon, signed a preliminary contract for the supply of at least one rotorcraft. Moreover, even the Pentagon and the Royal Air Force of Great Britain were interested in a promising machine. However, many customers wanted to get a car with greater carrying capacity. The calculations of the economists of the company “Fairy” at the very beginning of the work showed that the most efficient financially would be the version of the rotorcraft capable of carrying 60-65 passengers. It was at 65 locations that several shipping companies insisted. Recycling of the project required substantial financial injections - about 8-10 million pounds. Because of this, the Rotodyne project at the very end of the fifties was in a very awkward situation. Potential customers did not want to pay for design work, and Fairey Aviation did not have its own funds.

In addition to their own problems with the financing of the project “Rtodayn” hit the plans of the British government. The reduction in government orders forced Fairy Aviation to become part of Westland, and the latter had no plans to develop the Rotodyne program. Funding promising rotorcraft was insufficient, which led to the tightening of tests. Because of this, most shipping companies have abandoned their plans. In the 1962 year, despite initial plans for the launch of mass production, the Rotodyne project was closed. An interesting and courageous aircraft could not cope with the bureaucracy, financial problems and mistrust of merchants.

Kamov Ka-22

Almost simultaneously with the creation of the English “Rotodain”, a somewhat similar project began in our country. Rather, only the terms of the main design work coincided roughly, and the ideas of both projects appeared at the end of the forties. The first Soviet rotorcraft with suitable characteristics for use in practice grew out of the idea of ​​towing a helicopter by plane. In this case, the towed car could switch to autorotation and save a lot of fuel. However, the practical use of the "helicopter" ligament did not look very convenient. It was decided to develop an aircraft that could combine all the positive features of the existing types.



By May 1952, the design bureau N.I. Kamov completed a preliminary draft of the future of the rotorcraft called Ka-22. Already in the early stages of the aircraft it was proposed to make a twin-screw, with a transverse arrangement of rotors. In addition to the relative simplicity of the airframe design, this made it possible to significantly simplify the transmission: the engines located in the engine nacelles under the rotors could simultaneously drive the pulling screws. In fact, the most difficult part of the transmission was the synchronization mechanism, which provided simultaneous identical rotation of both rotors and, in the event of a shutdown of one of the engines, which distributed the remaining power. At the same time, the Ka-22 scheme at that time was considered not entirely suitable for mass exploitation. All previous cross-section helicopters suffered from the same problem - strong vibrations. Then there was an opinion that structural vibrations are an organic disadvantage of the transverse arrangement of the screws.

It is worth noting that, in addition to vibrations, the promising project had a number of other problems. For example, the calculations showed the need to create a power plant and transmission capable of operating at capacities of the order of 12 thousands of horsepower. Also had to spend a lot of time studying screws. With a flight speed of about 400 km / h, the flow velocity at the ends of the rotor blades exceeded the speed of sound, which significantly impaired their characteristics. Nevertheless, the designers of the Kamov Design Bureau and the TsAGI employees coped with aerodynamic and engineers problems. Ten years after those works N.I. Kamov defended his doctoral thesis, which was partially related to the Ka-22 project. According to M.L. Mile, for this project it was necessary to immediately give the degree of doctor of technical sciences.

The finished project looked like this. On the fuselage of the section, which is close to rectangular, the tail assembly of the stabilizer and keel was mounted. In the middle part of the fuselage, a wing span of the 23,8 meter was installed, at the ends of which two engine nacelles were installed for D-25ВК engines with 5500 horsepower. The engine nacelles also housed the transmission systems, which distributed power to the bearing and pulling screws. The empty Ka-22 weighed almost 26 tons. Maximum payload exceeded 16 tons. In this case, in some cases, a rotary-wing aircraft could carry no more than five tons of cargo - in this case, an acceptable range was achieved.



The first prototype of the Ka-22 rotary-wing was built in the 1958 year, but after the transfer to the flight test station, some improvements were needed. Because of them, the first flight took place only in the middle of 59. By the end of the year, flight tasks were added to helicopter-based flights, which included the inclusion of pulling propellers. 29 April 1960, the first circle flight ended soon after the start. The crew of the pilot D.K. Efremova a few seconds after takeoff, he felt a strong vibration and was forced to sit near the airfield. The reason for the trouble was the separation of the skin of one of the blades of the right rotor. In the future, tests of the Ka-22 were repeatedly interrupted for a short time due to constant technical flaws and improvements. However, in November, 1961, the new rotary-wing set a world record, lifting 16485 kilograms of cargo to the height of 2557 meters.

The most serious accident during the tests of the Ka-22 happened at the end of the summer of 1962, when an experienced prototype of the helicopter wing crashed, which overtook from the Tashkent aircraft factory to Moscow. When entering the Dzhusaly airfield, the aircraft fell on its side and fell to the ground, burying seven crew members under it. The cause of the incident was the disconnection of the fastening clutch of the control cable pitch of the right rotor. The second overtaking rotorcraft was sent for inspection and revision. Tests resumed only in the spring of next year. The new stage of flights according to its program repeated the previous ones: first take-off with the help of rotors, and then test flights "in an aircraft-like" manner. The latest tests were generally successful, but the rotorcraft still required fine-tuning for use in the air force. During the tests, the car reached a maximum speed of 356 kilometers per hour. A further increase in airspeed was associated with a certain risk, but the bar in the calculated 400 km / h could still be subdued.

However, the finishing was not needed, and the speed of four hundred kilometers per hour remained unattained. Even at the end of 1963, the Ka-22 project remained at the stage of testing prototypes. By this time, its main competitor, the Mi-6 helicopter, went into series and was put into service. The Ka-22 was originally designed as an alternative to the new heavy-duty helicopter. Difficulties in the design and testing of the finished rotary wing ultimately affected the timing of the project, which ultimately put an end to it. The aviation industry leadership and the Department of Defense have lost interest in a complex and lengthy project in 1964. Work on the Ka-22 stopped.

Lockheed AH-56 Cheeyenne

The company Lockheed has always been famous for its advanced developments. Often, the implementation of new ideas cost the customer large sums or stopped due to technical problems, but this almost did not affect the “zeal” of the designers. In the sixties, Lockheed employees tried their hand at creating rotary-winged cars. Needless to say, the project turned out to be interesting and, to a certain extent, bold? The resulting rotorcraft AH-56 Cheeyenne still attracts the attention of experts, but the actual fate of the project was sad.

Projects of "rotorcraft" type aircraft. Part I


In the mid-sixties of the last century, the Pentagon wanted to get a new attack helicopter with good flight and combat characteristics. The program of the military department received the designation AAFSS and 12 design organizations were involved in it. Only two companies entered the final stage of the competition - Lockheed with its project AH-56 Cheeyenne and Sikorsky with S-66. The technical requirements for the new helicopter was listed as high speed. The military assumed that the new attack helicopter should spend the minimum amount of time to reach the area of ​​attack. For this reason, both projects included the installation of a pushing screw in the tail end of the helicopter. This fact makes of the helicopter-class aircraft made from the helicopters in question. It is noteworthy that the engineers from Lockheed and Sikorsky chose different ways of countering the rotor's reactive torque. “Lockheed” arrived simply: a three-blade pushing driver, located at the very end of the tail boom, was added to the tail rotor with four blades. Sikorsky designed a special mechanism that unwrapped the steering screw on 90 °. After such a turn, the rotor went into autorotation mode and did not create a reactive moment. However, the customer found the S-66 helicopter to be too complicated. In 1966, this project was closed in favor of Lockheed AH-56 Cheeyenne.

The relative simplicity of the layout of the tail section of the Cheyenne was more than compensated for by the overall courage of other technical solutions. The helicopter-rotary-wing got a thin fuselage with a convex glazing of the cockpit. For the recognizable characteristic shape of the rotorcraft got the nickname Dragonfly - "Dragonfly". At the top of the fuselage, a low-profile screw bush was installed, on which three blades were hung. For the helicopters of the time, the three-bladed propeller was a bold decision. Most of the rotary-winged machines of that time had an even number of blades for easier balancing and reducing vibrations. In the middle part of the fuselage, behind the screw hub, was a turbo-shaft engine. In the first copies of the AH-56, it was a General Electric T64-GE-16 with a power slightly less than 3000 horsepower. With a maximum take-off weight of about 7700 kg, the Cheyenne could carry up to 1700 liters of kerosene. This gave the rotary-wing a unique maximum range - up to 1400 kilometers. Despite the low weight, the important helicopter units and crew had anti-bullet and splinter armor. The crew of two people was located in a common cabin; the pilot's workplace was located behind and above the navigator-gunner's workplace.

Understanding the great future of combat helicopters and rotary-winged aircraft, the designers of Lockheed did not begin to “waste time on it” with avionics. Its main element was the sighting and observation system General Electric XM-112. The system included 12 periscopes, a laser rangefinder and a night vision device. Thanks to XM-112, the shooter could control the 210 ° wide sector in front of the car. A turn on the yaw could provide a circular review. The XM-112 system was combined with the targeting complex of the newly created BGM-71 TOW anti-tank missiles. Missiles and other weapons were placed on six pylons under the wing. Also, three radio stations were built into the weapons monitoring and control system for communication with the base and ground connections, the “friend-foe” identification system equipment, a radio altimeter, a course automatic, and other necessary radio-electronic equipment. A characteristic feature of the avionics "Cheyenne" was the maximum integration of all equipment. Compared to the previous helicopters, the amount of various electronics practically did not affect the convenience of handling it. The only disadvantage of advanced avionics is the high price of the whole complex. However, in those days, the US military did not stint on military equipment.



A potential rotary wing operator Sheeyenne could choose weapons from a fairly wide range. So, in the nose of the combat vehicle placed a remote-controlled turret of the company Emerson Electric. A six-barreled rifle caliber of the Gatling XM-196 system, 40-mm automatic XM-129 grenade launcher or XM-52 automatic cannon of the 30 caliber of millimeters could be placed under the spherical turret housing Ammunition of different barrel systems was different, but in the nose of the rotary-wing there was enough space to accommodate the boxes with cartridges or shells. At six nodes of the external suspension, it was possible to carry another 907 kilogram of weapons, for example, blocks of unguided rockets or an ATGM TOW. In general, the combat potential of Cheyenne significantly exceeded the capabilities of the recently created Cobra AH-1.

Above were the flight characteristics of the new rotorcraft. At a height of a thousand meters, the AH-56 climbed in less than a minute and could fly a distance up to 1400 kilometers. During the tests, the maximum speed in 407 kilometers per hour was reached. 21 September 1967, the first flight prototype of the helicopter took off. He clearly showed the convenience of a high-power engine and an applied system with two tail screws. However, during the transition from hovering to level flight, as well as during the latter, the Cheyenne behaved unstably. Minor improvements interspersed with test flights. This practice lasted until the spring of the year 1969: March 12, the third flight copy crashed. During the flight, the main rotor began to vibrate, causing him to hit the lantern. The blow was so strong that the pilot D. Bale, who was in the upper cockpit, immediately died. After this incident, there was a proposal to equip the rotorcraft with ejection seats and a system for ejecting blades. By this time, the total number of Cheeyenne constructed or under construction was eight.

Cheyenne had a lot of technical and operational problems. The staff of Lockheed was actively working to eliminate them, but the Vietnam War was already in the active phase. The US military urgently needed an attack helicopter, which soon became the AH-1 Cobra. By the end of spring 69, the Pentagon broke the contract with Lockheed. The favorable offer in the amount of about one hundred million dollars was received by Bell. Later followed by other contracts for several hundred shock "Cobras". As for AH-56, Lockheed, on its own initiative and at its own expense, continued the project. The Cheyenne version of the AH-56A had an updated chassis, a new four-blade propeller and a more powerful General Electric T64-GE-716 engine. In addition, the composition of the equipment was adjusted and the production technology was slightly simplified. In accordance with the new project, two rotorcraft wings were built. In 1972, Lockheed presented a renewed combat vehicle to the military, but they no longer showed any interest. The project was finally closed, and soon the Pentagon began a new program, which resulted in the AH-64 Apache helicopter.

The first rotary-winged aircraft of the Lockheed Company was too complex and brave for its time. In addition, "Cheyenne" was not lucky to appear at the right time. Because of the fighting in Vietnam, the main customer lost interest in a promising machine, even if it was an unusual rotorcraft class. Of the ten built by AH-56, only four specimens survive to this day, which are now museum pieces.


On the materials of the sites:
http://china-defense.blogspot.ru/
http://militaryparitet.com/
http://airwar.ru/
http://aviastar.org/
http://globalsecurity.org/
http://pkk-avia.livejournal.com/
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  1. Civil
    Civil 16 November 2012 09: 09
    +1
    Meanwhile, our Chinese friend steps quickly:

    Chinese helicopter UAV V750 launched in a series

    V750 - the largest Chinese UAV helicopter type. It has a maximum take-off weight of 757 kg, a payload of up to 80 kg. The maximum flight altitude is 3000 meters, speed up to 161 km / h. The device can be controlled from a ground control station at a distance of up to 150 km, flight duration up to 4 hours, flight range up to 500 km. The first flight took place in May 2011.

  2. Tjumenec72
    Tjumenec72 16 November 2012 10: 55
    +1
    Sikorsky X2 still somehow looks more interesting (copy it go)

    ... they swung at the disco! (in the top left corner)
  3. mamba
    mamba 16 November 2012 16: 19
    +1
    The Ka-22 rotorcraft has a very large wing area, blown by rotors, which, of course, reduced their efficiency. Maybe it would make sense to change their profile and make them narrower at the fuselage and expanding towards the handballs. Something like this was done at Mil in the Mi-12.
  4. Lucky
    Lucky 16 November 2012 17: 28
    +1
    It's time to even come up with a replacement MI-8, the same for a decade!
  5. Zerstorer
    Zerstorer 17 November 2012 10: 05
    0
    You can also specify devices such as XV-2A, XV-3, XV-15, XV-22.
  6. Windbreak
    Windbreak 17 November 2012 11: 28
    0
    And where are the convertiplanes?
    1. Zerstorer
      Zerstorer 18 November 2012 09: 46
      0
      Okay, I agree. We, unlike the bourgeoisie, have a clear separation of the rotorcraft and tiltrotor. Amers do not have such a clear division - they can all be called a combined aircraft.