Coaxial arrangement of helicopter propellers: pros and cons


Coaxial helicopter propellers are not often used in modern helicopter manufacturing. The only helicopters with such a propeller scheme that are in serial production are the Russian Ka, including the famous Ka-52 Alligator. But what explains the rarity of using a coaxial screw design?


As you know, the most common in world and domestic helicopter industry is a scheme with one main rotor and an open tail rotor, which is designed to compensate for the reactive moment from the main rotor. After all, he “spins” the helicopter in the direction opposite to the rotation of the rotor.

The undoubted advantage of the steering scheme is constructive simplicity, relatively low maintenance and repair costs. But losing the tail rotor, the helicopter loses control and crashes.

The coaxial propeller scheme is less common, but its use makes the helicopter more tenacious and, accordingly, more adapted to the performance of combat missions. Interestingly, the use of a coaxial scheme is the result of the work of Soviet and Russian designers.

The first domestic helicopter with a coaxial design was introduced in 1948. It was the Ka-8 "Irkutian", released by the Kamov Design Bureau in only three copies. Then released the Ka-10 and Ka-15. The last helicopter became the first product of Kamov Design Bureau, which entered serial production. So in the Soviet Union began the serial production of helicopters with a coaxial propeller circuit.

Unlike the classic single-screw design, putting a coaxial design into practice is much more difficult. Experts call it one of the most outstanding achievements of Russian helicopter industry. But the complexity in the design and execution is offset by the undoubted advantages of the coaxial scheme.

Firstly, coaxial helicopters have smaller dimensions, high compactness, which increases angular speeds and makes the machine more maneuverable. In particular, such a helicopter is capable of performing figures “funnel”, “oblique loop”, which cannot be performed by helicopters of the classical scheme with tail rotor.

Secondly, coaxial helicopters have greater combat survivability due to the lack of a tail rotor with its gearbox and drives. At the same time, it is easier for a helicopter to maneuver near the ground or other surface on which it can land.

Thirdly, in coaxial helicopters, the weight coefficient is higher, that is, the ratio of payload to total flight weight.



Such characteristics of coaxial helicopters determined the specifics of their application. Coaxial helicopters are much more efficient as deck helicopters aviation, they can be used in mountainous regions with their difficult meteorological conditions. So, the Ka-50 was actively used during the hostilities in the North Caucasus.

At the same time, coaxial helicopters, for all their undeniable advantages, have certain disadvantages. The most significant minus for their mass production is the high cost. According to experts, the Mi-28 is inferior to the coaxial Ka-52 in almost all respects, but the cost of the latter is much higher, and we are talking about millions of dollars.

Experts also note the complexity of the coaxial helicopter control system, the risk of significant vibrations, insufficient track stability, and the danger of collisions between blades rotating in opposite directions.

Currently, the main modern attack helicopter of a coaxial design is the Ka-52 Alligator. These combat vehicles have been successfully tested in Syria, showing themselves well in an unusual climate for Russia. Ka-52 helicopters are part of both army aviation and carrier-based aviation of the Russian Navy.
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  1. Ros 56 April 16 2020 10: 45 New
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    Well, the author is strong, but we did not know. What you won’t do for the sake of dough. fool
    1. Genry April 16 2020 11: 36 New
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      The author wrote his article as a poet poetry - that in his head it was then put on paper.
      It just didn’t appear in my head that the coaxial circuit is resistant to gusts of wind, has less engine power consumption, is not subject to the fatal phenomenon of a “vortex ring”, it can equally make left and right turns (uniaxial helicopters make circles in one direction, which makes it easier to catch them anti-aircraft means).
      1. tarabar April 16 2020 12: 40 New
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        Colleague, let me object to you, regarding the left and right turns. I saw a documentary film about the creation and testing of the Ka-50, where either a design engineer or a test pilot talked about the features of the coaxial design, so he just said that on this diagram it is not possible to equally perform the left and right turns, since in one of them there is overlapping of the blades. And they even said, look thin. the film "Black Shark", where all the spectacular turns are performed in one direction, because in the other it is not so graceful and spectacular. I did not remember the explanation of the physics of the process, but such a fact was recorded in memory reliably.
        1. ProkletyiPirat April 16 2020 13: 25 New
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          Quote: tarabar
          Colleague, let me object to you, regarding the left and right turns.

          This applies to any helicopter; this is the nuance of the rotor blade swashplate.
        2. vertolet April 18 2020 11: 11 New
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          nothing of the kind! flew all my life on a coaxial scheme, flew on tailed ones, that the left, that the right turn is easy and simple, flew over 3000 hours, believe me! and nothing better than Kamov’s helicopters I have ever seen and never seen!
      2. EvilLion April 17 2020 09: 14 New
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        In fact, the overlap of the blades is just the result of getting into the vortex ring and driving the classics into it is somewhat more difficult.
        1. Genry April 17 2020 13: 11 New
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          Quote: EvilLion
          In fact, the overlap of the blades is just the result of getting into the vortex ring

          Overlapping occurs only at overloads above the limit values ​​(vigorous aerobatics), which leads to a critical bending of the blades ...
          When the screws rotate in different directions, the circular motion of the air is compensated - here the vortex ring is fundamentally impossible.
          Quote: EvilLion
          into a vortex ring and the classics to drive into it is somewhat more difficult.

          Classic, at near-zero horizontal speed (landing, hovering) itself enters the risk zone of creating a vortex. Only with sufficient horizontal speed, when the blades capture fresh / standing air, can it fly safely.
          1. EvilLion April 19 2020 12: 19 New
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            Can’t you see mutually exclusive paragraphs? The classic chopping the tail boom with the screw under the same modes in which the coaxial can catch the overlap.
            1. Genry April 19 2020 16: 09 New
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              Quote: EvilLion
              Can’t you see mutually exclusive paragraphs?

              I don’t see .... and what I don’t know in your head. Write!
              Quote: EvilLion
              The classic chopping the tail boom with the screw under the same modes in which the coaxial can catch the overlap.

              This British designer beam closer to the screw? In Russia, this does not seem to be ...

              And you changed the topic. It seemed to you that the co-drivers create a vortex funnel ...
  2. Siberian 66 April 16 2020 10: 51 New
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    So, the Ka-50 was actively used during the hostilities in the North Caucasus.
    As far as I know, they didn’t really show themselves there, just. By the set of malfunctions and problems with the car, they stood more than they flew. They dragged the Mi-24 as usual.
    1. Lopatov April 16 2020 11: 10 New
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      Quote: Siberian 66
      As far as I know, they didn’t really show themselves there, just.

      They did not show themselves.
      Due to reinsurance of command.
      It is unclear why, in general, such "tests" to conduct.
      1. Lipchanin April 16 2020 11: 30 New
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        Quote: Spade
        They did not show themselves.
        Due to reinsurance of command.

        Behind them, the Mi-24 link went for insurance and protection
        1. Lopatov April 16 2020 12: 18 New
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          Quote: Lipchanin
          Behind them, the Mi-24 link went for insurance and protection

          The men who were sticking out in Khankala told that they only flew at night.
          1. Lipchanin April 16 2020 12: 25 New
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            Quote: Spade
            The men who were sticking out in Khankala told that they only flew at night.

            And even then not too often.
            So, what kind of tests there were there, it was completely incomprehensible.
            I read that the “Kamovites” have long and unsuccessfully proved that a single-seat helicopter is preferable to a double. When they did, it turned out that one pilot simply physically could not cope with all the tasks.
            Therefore, they returned to the double layout.
            By the way, as far as I know, the Black Shark action movie was funded and commissioned by Kamov
            1. Lopatov April 16 2020 12: 31 New
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              Quote: Lipchanin
              I read that the “Kamovites” have long and unsuccessfully proved that a single-seat helicopter is preferable to a double. When they did, it turned out that one pilot simply physically could not cope with all the tasks.
              Therefore, they returned to the double layout.

              According to rumors first-hand nothing "turned out" Just uncles with stripes decided "luminous", and the Kamovites had to obey

              By and large, to "find out" in this matter requires serious research. And the Ka-50 appeared exactly at the time of the degradation of our military science. Up to coup de grâce under Medvedev-Serdyukov
              1. Lipchanin April 16 2020 12: 47 New
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                Quote: Spade
                According to rumors first-hand nothing "turned out" Just uncles with stripes decided "luminous", and the Kamovites had to obey

                Quite possible. I will not argue. Rumors, as you know, the Russian land is full
              2. Alexey RA April 16 2020 20: 48 New
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                Quote: Spade
                According to rumors first-hand nothing "turned out" Just uncles with stripes decided "luminous", and the Kamovites had to obey

                In fact, the ultimate load with one crew member was revealed on the Su-25T with the same Ka-50 PrNK:
                On the Su-25T was the same as on the Ka-50 Prnk "Flurry".
                One of the remarks of the List No. 1 of the GI Su-25T Act is written something like this (I don’t remember the exact wording, more than twenty years have already passed): "When certain combat regimes are carried out, the psychophysiological load on the pilot is close to the limit." The remark was given by specialists of the Research Institute of Aviation and Space Medicine of the Moscow Region. Those. the combination of the aiming and piloting process in a number of modes caused problems. Moreover, it was not about combat pilots, but about military test pilots of the first class.
            2. EvilLion April 17 2020 09: 16 New
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              Yes, then there were norms with directors and scriptwriters, and even the promotional film turned out to be good and just like an action movie of its genre.
          2. Alexey RA April 16 2020 20: 45 New
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            Quote: Spade
            The men who were sticking out in Khankala told that they only flew at night.

            Judging by the Ka-50 video in Chechnya, they flew during the day: a pair of Ka-50 and one Ka-29.
            1. EvilLion April 17 2020 09: 18 New
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              Do you know that, on the Ka-50, in principle, there was no equipment for night flights, maximum NV pilot points?
              1. vertolet April 18 2020 11: 15 New
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                complete nonsense! the helicopter is designed for flying day and night in SMU! otherwise it would not be released!
                1. EvilLion April 19 2020 12: 21 New
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                  A helicopter and equipment for flying day and night are mutually orthogonal things. Make equipment and put on a chaise, you will have night carts. In practice, in those years it was not necessary to talk about any nighttime use of helicopters at all. Mi-28N in this regard was no different.
      2. EvilLion April 17 2020 09: 15 New
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        That the war did not win in 2 persons? Bullshit, not a helicopter.
    2. timothy61 April 16 2020 14: 12 New
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      So you don’t know well, so they were not allowed to go home for so long.
    3. EvilLion April 17 2020 09: 15 New
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      They showed themselves very well there, but one car received combat damage to the blade and stood waiting for a replacement.
    4. EvilLion April 17 2020 14: 15 New
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      After the EMNIP of 19 sorties, there was only one machine, which was pierced by a fragment of a blade, but there was no replacement. Do not write nonsense.
  3. Pavel57 April 16 2020 10: 51 New
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    Is a coaxial circuit better than a synchropper?
    1. The leader of the Redskins April 16 2020 11: 05 New
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      Hush! And then tomorrow the author will explain it to us in the same manner!
    2. EvilLion April 17 2020 09: 19 New
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      And FIG knows her, except for the "Kaman" nobody builds synchroppers, although they also had separate successful models.
  4. Uncle lee April 16 2020 10: 52 New
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    the use of a coaxial scheme is the result of the work of Soviet and Russian designers.
    - That's the most important thing!
  5. Aleks2048 April 16 2020 10: 53 New
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    And was it worth it to write an article for the sake of repeating hackneyed truths and even not backed up in numbers? But it’s also placed in the analytics section ... What kind of analysis is more-less, generally moderate? Where is all that should be in the article? Materials science, engines design features, load analysis and more. An article for the sake of an article.
  6. helmi8 April 16 2020 10: 58 New
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    But losing the tail rotor, the helicopter loses control and crashes.

    In case of failure of the track control, the helicopter lands in an airplane ...
    1. Nikolaevich I April 16 2020 11: 34 New
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      Quote: helmi8
      In case of failure of the track control, the helicopter lands in an airplane ...

      It’s only a pity that for some reason pilots didn’t know about it, who died with the “passengers” after chopping off the “tail”!
    2. Bacha April 16 2020 12: 10 New
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      By plane? And how to deal with the reactive moment from the rotor? It’s for me, purely for myself, so to speak, to broaden my horizons.
      1. helmi8 April 16 2020 12: 24 New
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        Quote: Bacha
        By plane? And how to deal with the reactive moment from the rotor? It’s for me, purely for myself, so to speak, to broaden my horizons.

        In short, like this ...
        In case of violation of control from the pedals to the tail rotor, its blades under the action of centrifugal, aerodynamic and elastic forces will be set at an angle of 5 °, at which the helicopter will be balanced without sliding at a horizontal flight speed of 70 km / h on the instrument.
        In case of failure of the track control system, balance the helicopter by sliding, reduce the flight speed to 70 km / h on the instrument, select the nearest site for a safe landing and, balancing the helicopter by sliding, land on an airplane.
        When the tail rotor drive is destroyed, the helicopter turns sharply to the left and rolls to the right. In this case, immediately reset the rotor pitch to the minimum, completely remove the gas correction to the left, counter the roll with the control knob, and proceed to planning on the rotor self-rotation mode without turning off the engines.
        On planning, balance the helicopter by sliding, gradually increasing the engine operating mode in order to reduce the vertical speed of descent. At a height of 100-150 m, turn off the engines.
        Helicopter landing on the selected site against the wind in an airplane using the common pitch of the rotor.
        If balancing the helicopter is not possible, decide on leaving the helicopter
        . ©
        1. Bacha April 17 2020 07: 24 New
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          Thank. We will know.
        2. EvilLion April 19 2020 12: 26 New
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          Translated from technical into plain Russian. "The situation is extremely bad, you can try, this and this, if it does not help, or there is no place for planting, then tick the lads." Obviously, the passengers of some Mi-8 in the latter case are simply doomed.
    3. EvilLion April 19 2020 12: 23 New
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      Have you ever seen how this happens? In order to at least somehow land the helicopter must have at least high speed, maybe then it will turn out to fend off something and flop somewhere, if there is still somewhere. The hanging helicopter after the failure of the tail rotor just then falls with a rotating stone.
  7. gridasov April 16 2020 11: 02 New
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    This is the case when it is necessary to talk about mathematical principles or methods for constructing methods. This is not a pun. The designer’s consciousness itself is trying to solve problematic issues by linear methods or by simply adding new mover elements. In this case, the problem must be solved by increasing the energy density, and therefore new fundamental solutions
    1. Peter is not the first April 16 2020 11: 52 New
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      Cool and to the point! Did our President get a "weapon based on new physical principles"?
      So, increasing the energy density, we will not get a helicopter, but a rocket, but it has already been invented, and it does not need any screws. Each type of mover has its own niche in technology and weapons, and each mover has limits when you need to abandon one, for example, from a screw, and go to a jet engine.
      1. gridasov April 16 2020 13: 43 New
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        To a certain extent, you are right, if you apply the new principle in a turbo-fuel supercharger, then the rocket engine will turn out to be more efficient.
  8. andreykolesov123 April 16 2020 11: 21 New
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    And why a combat helicopter aerobatics? Will it save him from the earth air rocket?
    1. Peter is not the first April 16 2020 11: 55 New
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      Most likely it will not go away from the rocket anyway, but it may already try to go from the ATGM. But if it’s more serious, then in order to quickly reach the line of fire and have time to destroy more targets in one flight.
      1. ProkletyiPirat April 16 2020 15: 01 New
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        The advantage of the aligner is not that it is "faster", but that it is less affected by atmospheric turbulence during extremely low-altitude maneuvering when air flows are reflected from the surface and objects.
        1. Peter is not the first April 16 2020 15: 04 New
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          In the context of kmmentarium, the word "faster" was understood not as speed but maneuverability.
  9. Zaurbek April 16 2020 11: 28 New
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    . According to experts, the Mi-28 is inferior to the coaxial Ka-52

    Make an article comparing who and what is inferior. We don’t take into account different avionics and weapons ... and they have equal losses in Syria.
  10. Zaurbek April 16 2020 11: 30 New
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    There is still a similar circuit with two screws next ..... interesting to compare with it.
  11. The comment was deleted.
  12. Undecim April 16 2020 12: 03 New
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    On the one hand, the site turned for help. On the other hand, the site is really a good platform for communication "through mountains and distances" and exchange views.
    With the third - the authors of the site for the most part “scored” the quality of the articles and give out solid husk to the mountain. Well, was it really impossible for this article to devote more time to an hour and a half and get a really interesting publication? What prevented me from picking up some information on the issue and filling the article with content?
    Interestingly, the use of a coaxial scheme is the result of the work of Soviet and Russian designers.
    Well, not only that.
    In the book "Principles of Helicopter Aerodynamics" the Cambridge University Press says that the first who proposed a coaxial scheme was a Russian scientist M.V. Lomonosov.

    in early 1754, Lomonosov made a message at the Russian Academy of Sciences, which is recorded in the minutes of the meeting of the academy as follows:
    “Mr. Advisor and Professor Lomonosov presented to the assembly a small typewriter that would raise thermometers and other small meteorological instruments, and suggested that they draw a drawing; for the sake of the gentlemen, they were trying out his presentation and asked the Chancellery of the Academy of Sciences to request a report so that it would be free to order According to the figure attached to this experiment for the experience of this invention, make a speeded car under his master’s author by looking at the master Futsius. go meeting of March 4 days 1754 "
    The first patent for an aircraft heavier than air coaxial scheme received in 1859, Briton Henry Bright.
    The first operational coaxial helicopters were built in Italy (Corradino D'Ascanio) and France (Gyroplane Laboratoire) in the early and mid 1930s.
    1. Undecim April 16 2020 12: 10 New
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      By the end of the thirties, fully-fledged projects had already appeared, such as the Dorand Gyroplane G. 20 of the French aircraft designer Doran, but interrupted the beginning of World War II in this direction.

      At the end of the war, work resumed and Kamov was already in the lead, whose first helicopter, the Ka-8, took off in 1947.
      1. agond April 16 2020 12: 55 New
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        In addition to the above helicopter circuits, it is necessary to recall the French Sud-Ouest SO1221 Djinn helicopter with a jet (compressor) rotor drive, 1960 machines were built by 178, some still fly, the rotor is driven by compressed air supplied by a turbocompressor to nozzles mounted on ends of propeller blades
        Take-off weight: 800 kg.
        engine: 1 Turbomeca Palouste IV turbocharger, power 179 kW (240 hp)
        Maximum speed: 130 km / h.
        Flight Duration: 2 hours 15 minutes
        If we divide the take-off weight of 800 kg by the power of 240 hp, we get 3.3 kg / hp for the Ka-52, this figure is 3.8 kg / hp, and for the Mi-8 13000 kg we divide by 4000 hp, we get 3.25 kg / hp, thus we see that the scheme for the Sud helicopter -Ouest 1957 and now worthy of attention
      2. Avior April 16 2020 13: 37 New
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        Bréguet-Dorand Gyroplane Laboratoire, 1935

        Kaman HH-43 Huskie - synchropper, two shafts with cross screws, 1947

        Kamov Ka-8, 1947
        1. Undecim April 16 2020 13: 50 New
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          These are different schemes, firstly. Secondly, the Kaman HH-43 Huskie made its first flight in 1953.
          If we mention the "pioneers" who built the cars according to the synchropert scheme, these are the Germans. Their Fl.282 Kolibri (1941) was mass-produced and was in service.
          1. Undecim April 16 2020 13: 55 New
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            And that Kaman’s apparatus, which flew in 1947, did not look any more “menacing” than the Kamov’s apparatus.
            1. Avior April 16 2020 14: 22 New
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              did not look any more “threatening” to Kamov’s apparatus.

              markedly different, judging by the photo
              1. Undecim April 16 2020 14: 27 New
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                Both that and another - prototypes for development of a design. Dimensions in this case do not matter.
                1. Avior April 16 2020 14: 31 New
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                  design prototypes

                  double?
                  it remains only to sheathe a cloth with varnish - and the finished helicopter
                  What can not be said about the Ka-8
          2. Avior April 16 2020 14: 06 New
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            a prototype arose in 1947, and a production helicopter later
            If you look at the Ka-8, then it is clear that both he and the Ka-10 of 1949 are not even prototypes, but experienced stands made of tubes, a motor and screws.
            There were a lot of them then, even among the Chinese
            https://plane-encyclopedia.com/cold-war/chu-hummingbird/
            there were real coaxial helicopters
            Brantly B-1, 1946

            Bréguet G. 111, 1949

            The first real Kamov helicopter is the Ka-15, 1955

            So it cannot be said that after the war it was Kamov who gained leadership in coaxial helicopters.
            Kamov simply continued to deal only with such a scheme, while others departed from it. The reasons for this are the subject of a separate serious study.
    2. ProkletyiPirat April 16 2020 15: 06 New
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      Quote: Undecim
      Well, was it really impossible for this article to devote more time to an hour and a half and get a really interesting publication?

      An interesting article is written for months, not an hour or two, and the site earns money from traffic and advertising, so the logical result of the life of such resources is to slide down to the copy-paste of the news ... crying
      1. Undecim April 16 2020 15: 21 New
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        An article for months? No, you can, of course, write for years. But still, for the level of VO for months - that’s what you grabbed over the edge.
        1. ProkletyiPirat April 16 2020 15: 37 New
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          That's it, "for the level", which is steadily falling for all such resources aimed at advertising traffic ..
  13. Avior April 16 2020 13: 43 New
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    Ka-8 is the first helicopter in the world.
    By the summer of 1948, the money allocated for the creation of the Ka-8 was over, and the Minaviaprom was not going to continue supporting the unpopular topic. Kamov’s employees were no longer paid salaries, and even there was nothing to buy “spirtzin”. The situation was saved by the inclusion of "Irkutyanin" in the program of the traditional air parade in Tushino, under which Kamov pushed off the continuation of work for a month and a half. Shortly before the Ka-8 parade, they managed to show Vasily Stalin, the aviation commander of the Moscow Military District. Gurov performed a short demo flight. who did not leave the general and experienced pilot indifferent: “Great! Get ready for the parade. ” Trying to show the car most effectively to potential customers, Nikolai Ilyich suggested using a platform mounted on the back of a truck as an aerodrome. This circus trick Vasily Stalin liked, and he was included in the plan of the parade. The day before the air festival Kamov was called to the Chief Marshal of Aviation K.A. Vershinin to clarify the program of speech and the accompanying announcer's text. During the discussion, Kamov proposed the use of the term “helicopter”, which he coined, which, in his opinion, was more suitable for naming rotorcraft than the English term “helicopter” used then. The proposal was received very approvingly, the “helicopter” was introduced into the announcer's text, and soon this easily pronounced word grew into our speech.

    Before that there were helicopters.

    In general, the Ka-8 show made the most favorable impression not only on ordinary viewers, but also on the country's leaders. Stalin himself conveyed his congratulations to Kamov and, right during the parade, ordered the Minister of Aviation Industry to provide the designer with all the opportunities for the full continuation of work. The helicopter was requested the next day at the Navy Air Force Research Institute. Since one instance of the Irkutianin was not enough to conduct comprehensive tests, an urgent task was received to produce two more similar machines. The simplicity of the Ka-8 design made it possible to fulfill the order immediately. Institutional tests did not last long and showed that in its original form, the Ka-8 is not suitable for use in the Navy. Because of the conical floats, the seaworthiness of the helicopter turned out to be simply no - at the slightest wave it tumbled back. Using cylindrical floats, this drawback was eliminated. The situation was worse with the power plant. Motor power was clearly small. Moreover, the motorcycle engine itself with its spirtzin was not suitable for a military aircraft. Despite this result, the main goal was achieved. By a decision of the Council of Ministers of the USSR of September 29, 1948, OKB-2 was recreated, headed by N.I. Kamov and received an order to develop a new version of the helicopter coaxial scheme.

    So with the parade and spirtzin (alcohol with the addition of gasoline to increase engine power) it all started ....
  14. Aviator_ April 16 2020 15: 52 New
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    Experts also note the complexity of the coaxial helicopter control system

    Strange experts. Helicopter pilots told me just the opposite, that it is easier to pilot a coaxial circuit.
    Actually, the fact that the Kamovites brought to mind this scheme, for which only the lazy did not undertake before, but abandoned it, deserves respect. They have some kind of know-how, which is irreproducible. However, the Americans also managed to bring to mind the longitudinal scheme of the CH-47 Chinook, which they still fly.
    1. su25 April 16 2020 23: 14 New
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      Still, the longitudinal and coaxial design are two big differences. The first shows its advantages in vertical take-off and hover modes, and the second - in maneuvering, due to the fact that all inertial and aerodynamic forces are applied near the center of mass.
      1. Aviator_ April 17 2020 09: 08 New
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        I gave the example of CH-47 only because the car is still flying, although in the early 60s there were many attempts to create such a model, but only Boeing succeeded.
    2. Aag
      Aag April 17 2020 09: 21 New
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      "The helicopter pilots told me just the opposite, that it’s easier to pilot a coaxial circuit."
      Management - piloting, the actions of the pilot to manage the aircraft.
      Control system - mechanisms, assemblies, devices, structural elements of the aircraft itself.
      1. vertolet April 18 2020 11: 18 New
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        much easier !!!
    3. EvilLion April 19 2020 12: 29 New
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      Longitudinal is also implemented in our Yakovlev Design Bureau, Yak-24. And he completely flew to himself, did not do widows. But now there is a Mi-26, so it’s not particularly interesting
      1. Aviator_ April 19 2020 15: 27 New
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        The Yak-24 was very quickly removed from service due to strong vibrations and fatigue strength. And Chinook flies.
  15. Operator April 16 2020 16: 42 New
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    The coaxial scheme gives an effect only with rigidly suspended blades that do not perform a flywheel movement and, accordingly, allow multiple reduction of the height of the rotor column. At the same time, a stiffer suspension makes it possible to increase the flight speed of the helicopter, naturally compensating for the stall in the retreating blades of one screw by increasing the lifting force on the advancing blades of the other rotor.

    The coaxial scheme makes it possible to use more innovative solutions such as replacing the flywheel with a cyclic torsional bending of the blades.
    1. su25 April 16 2020 23: 24 New
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      It depends on what is meant by "effect." Unlike the classical scheme, the aligner does not unbalance when heading, the left and right turns the same way, there is no loss on the tail rotor, which is especially noticeable in the vertical take-off and hover mode. A stiff suspension of the blades is not a panacea, as the experience of Sikorsky X2 showed. Abnormal flow around the retreating blade leads to a sharp increase in resistance, and, even worse, to the loss of stability of the blade.
      1. Operator April 17 2020 00: 43 New
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        The coaxial pair of screws also has losses - the lower screw works with reduced efficiency due to disturbance of the air flow by the upper screw.

        So I say - cyclic twist of the blades (a functional analogue of the flywheel movement) eliminates the growth of resistance and loss of stability of the blades.
    2. EvilLion April 19 2020 12: 30 New
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      A classic then only with a very low tail boom, otherwise it is regularly chopped with a rotor ..
  16. Operator April 16 2020 16: 56 New
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    Quote: Genry
    not subject to the lethality of the vortex ring

    Yeah yeah laughing
    1. Gust April 16 2020 20: 37 New
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      Probably, the vortex ring of the tail rotor was meant due to the lack thereof.
      1. su25 April 16 2020 23: 10 New
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        This is how you need to "twist" the helicopter so that the tail rotor gets into the "vortex ring"?
  17. vadivm59 April 16 2020 19: 56 New
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    when I meet the phrase "the famous KA-52 .." IMMEDIATELY THE QUESTION IS WHAT HE KNOWS. MI-8, this is a legend, without question, but how did you manage to become famous?
  18. EvilLion April 17 2020 09: 33 New
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    The main disadvantage of the nipple is that the first major successes with it appeared after the main modern helicopters were developed. The same Mi-8 comes from the 60s yet. A conditional Ka-29 civil still needs to be done, and somehow shove. In fact, the Ka-52 is the first successful attempt to introduce a nipple into a niche firmly occupied by existing classics.

    For the price, for military vehicles, the contribution of the circuit itself to the total cost is minimal. The same Ka-52 is not much more expensive than the Mi-28N, but the Ka-52 has a kind of radar. The Ka-26 was quite expensive, but this did not stop building it in large quantities, and the cost there is the result of modular design, with the ability to quickly install a new cargo compartment. But on flights in a straight line, the nipple is apparently less economical, since a large column of screws gives extra. resistance. It is clear that the helicopter cranes and the slow tugs of anti-submarine buoys do not give a damn about it, in their niches the nipple shines exclusively with pluses. The Ka-60 has a fenestron, perhaps because once you decide to make a classic, you need to run into reduced resistance to the end and remove the tail rotor from the stream. And in the case of the Mi-28N and Ka-52, it is not traced that the classics have less resistance, however, the Ka-52 itself looks more aerodynamic.
  19. Vladimir SHajkin April 18 2020 10: 56 New
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    I’m not a helicopter pilot, but I was embarrassed by one conclusion of a spacecraft more expensive than MI sometimes in the millions of dollars. This is stupid.
    You can make Misha of one series more expensive one from the other.
  20. Graduate engineer April 18 2020 17: 17 New
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    As one of the advantages of this scheme is indicated:
    “Coaxial-type helicopters have greater combat survivability due to the lack of a tail rotor with its gearbox and drives” - this argument was presented at the very beginning of the 1980s, when there was nothing to test on the BZ. The argument is out of date. Later, a different opinion appeared, directly opposite to that indicated. If a small charge, for example, a 35-mm or 40-mm OFZ or even a relatively small warhead (500 g) of a non-contact MANPADS above and below the screw planes, is under high probability, the blades will collapse due to flow disturbance by the action of a shock wave impulse. The result is clearly not good.
    1. EvilLion April 19 2020 12: 32 New
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      Or a blow to the tail boom, or even to the cab, so either this is an invention, or does not depend on the scheme at all, it will be equally bad.
  21. Kamaz April 18 2020 21: 24 New
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    What exactly increases the price of a coaxial helicopter?
    1. EvilLion April 19 2020 12: 32 New
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      Transmission. But not fundamentally.
  22. IL-64 April 22 2020 14: 55 New
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    And where is the detailed analysis? What the hell are fasting more and more?
  23. Chaldon48 April 22 2020 23: 07 New
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    If there are more pluses than minuses, then in spite of the high cost they should be in the troops as much as possible, because it is known that the value of any weapon is measured mainly by the damage that it can cause to the enemy.
    1. agond April 24 2020 21: 36 New
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      And so in the coaxial circuit there is a danger of overlapping screws, and in the circuit of a synchroopter with a working synchronizer there is no danger, but it requires two shafts, a slight increase in weight and greater drag, in principle, it would be possible to combine the two circuits into one, that is, both screws in fasten the coaxial circuit to swinging washers such as cardan or ball equal speeds (approximately as in front-wheel drive cars) so that in the coaxial circuit the screws rotate not in two parallel rotation planes, but in two intersecting planes tyah, that is, as well as in the intermeshing rotors, but with one axis !!! , and these same cardan or ball swing bushings as close as possible to each other, there are three options for the intersection of the planes of rotation of the screws in this combined coaxial circuit
      1 rotation planes are inclined to the right and left as in a conventional synchrometer
      2 and 3 planes of rotation are inclined forward or backward
      This hybrid will dramatically reduce the height of the helicopter and save it from the danger of overlap. while preserving the main advantages of the coaxial scheme, but also complicating the design, you will have to use special washers and a synchronizer. although it may already be in the gearbox. Ka-52
      1. agond April 24 2020 22: 09 New
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        Quote: agond
        swing bushings as close as possible to each other,

        I’m sorry, it’s impossible to bring the bushings as close as possible in the opposite rotation, but the circuit itself is, in principle, possible
  24. barin 3 May 2020 09: 45 New
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    Other countries either cannot repeat, or do not want ...