Military Review

Progress and failure. Technologies of the RAH-66 Comanche project


Experienced RAH-66 in flight

In early 1996, an experienced reconnaissance and attack helicopter RAH-66 Comanche, developed by Boeing and Sikorsky, made its maiden flight. Tests continued for several years, and in 2004 the Pentagon decided to close the project. The resulting helicopter did not fully meet the requirements, and was also too expensive and overly complicated. One of the reasons for the high complexity of the project was a number of new and bold solutions and technologies in different areas.

Against radars

The future RAH-66, developed under the Light Helicopter Experimental (LHX) program, had special requirements for visibility. The reconnaissance and strike vehicle had to literally hang over the battlefield - with understandable risks. Therefore, it was necessary to simultaneously reduce the radar, infrared and acoustic signature.

Progress and failure. Technologies of the RAH-66 Comanche project

Comanche and Apache in the air

The airframe for RAH-66 was designed using all available technologies and developments. It received a characteristic angular shape, formed by flat and curved panels, as well as rounded edges. The airframe skin was made of composites with a minimum reflection coefficient. In addition, a special coating with the function of absorbing radio waves was used.

The main and tail rotor became a serious problem in the context of stealth. The bushing of the carrier system was closed with composite fairings, and the blades were built with a minimum amount of metal and with all the necessary coatings. These measures made it possible to drastically reduce the reflections from the main rotor, although they did not exclude them. The tail rotor received composite blades and was placed in an annular channel. This eliminated radiation from the front corners, and also reduced signal reflections from the side.

The obvious advantages of stealth: the helicopter finds the enemy before it reveals itself

The Comanche was distinguished by the minimum number of protruding parts. So, the bow cannon installation could turn back along the fuselage and remove the barrel into a closed niche. Suspended armament was placed on the wings, retracted into the side cargo compartments of the fuselage. Open transportation was also provided weapons with increasing load and with increasing visibility.

The development companies reported that all these measures made it possible to bring the helicopter's visibility to the possible minimum. Depending on various factors, the RCS of the RAH-66 helicopter was 250-360 times lower than that of the AH-64 Apache combatant. Moreover, the EPR helicopter was compared with the AGM-114 rocket. However, the exact numbers have not yet been disclosed.

Infrared stealth

Measures have been taken to reduce the visibility in the infrared range. So, the airframe coating not only absorbed radio waves, but also had the function of a heat insulator. This prevented the heat from the internal units from heating the skin and unmasking the helicopter. In addition, it was necessary to create an original system of indoor units, which reduces heat emissions to the outside.

The use of composites in the fuselage structure

The RAH-66 helicopter was equipped with two LHTEC T800-LHT-801 turboshaft engines with a capacity of 1563 hp each. With a maximum take-off weight of 5,6 tons, this made it possible to obtain high flight performance. In addition, other advantages were achieved. In particular, the Comanche's powerplant produced less hot gases than the more powerful Apache engines.

Hot gases from the engines entered a specially designed cooling device located in the tail boom. They were cooled by the intake air and thrown into the rear hemisphere. The use of such cooling made it possible to more fully use the internal volumes of the airframe, as well as eliminate the need to install onboard shielding exhaust devices.

Retractable starboard weapons installation

Due to all these measures, it was possible to significantly reduce the thermal radiation from the helicopter and its exhaust. According to open data, the visibility in the infrared range was reduced by up to 4 times.

Reducing noise

A flying helicopter makes a noise that unmasks it at a great distance. This noise consists of the hum of the turboshaft engines and the sound of propellers. In the RAH-66 project, measures were taken to reduce the acoustic signature in flight.

Exhaust duct for gas cooling system

The noise issues were solved by optimizing the design of the propellers. The carrier system, called Pentaflex, received an original hub and a special blade design. They were designed to improve aerodynamics, reduce various vortices and therefore reduce noise - without sacrificing strength. It was also possible to reduce the propeller speed to reduce noise. Similar ideas were implemented on the tail rotor.

Combat capabilities

At the request of the customer, the LHX / RAH-66 helicopter had to solve several main tasks. It was planned to create a helicopter with the possibility of optical and electronic reconnaissance, as well as capable of striking ground targets and hitting aircraft. All this required the use of a number of new solutions.

Main rotor blade

RAH-66 received a fundamentally new sighting and navigation system with advanced computing facilities, a "glass cockpit" and a helmet-mounted display system. Integration into promising network-centric troop control contours was envisaged. In the future, the helicopter could receive a radar with an overhead antenna.

To defeat ground targets, it was planned to use AGM-114 Hellfire guided missiles, up to 6 units. on two pull-out units. It was also proposed to use AIM-92 Stinger air-to-air missiles - up to 12 units. If necessary, it was possible to combine ammunition. It was supposed to expand the range by using other weapons, incl. foreign. Detachable outer fenders were developed with one point of suspension on each, which made it possible to increase the ammunition load or add outboard tanks.

Tail rotor original design

Breakout price

In terms of technical solutions, technologies, etc. the Boeing-Sikorsky RAH-66 Comanche project was and is of great interest. Tests have shown that the helicopter is quite capable of coping with the intended tasks and showing very good results - it was only required to complete the fine-tuning.

However, the project turned out to be too bold and overly progressive, which led to a number of characteristic problems. First of all, the Pentagon and aircraft manufacturers were faced with a delay in work. The LHX program was launched back in 1982, and the experienced RAH-66 was only taken into the air in 1996. The research and design work, as well as the preparation and construction of the prototype, took almost 14 years. Tests and fine-tuning continued until 2004, and during this time it was not possible to solve all the tasks. Thus, the beginning of operation was shifted, at least, to the second half of the XNUMXs.

Combat load options with additional outer planes

The RAH-66 project was based on the experience of developing other helicopter technology, but provided for the widespread use of completely new ideas and materials. Some of the new technologies and units had to be developed anew, which required time and money. By the time the work was completed, they managed to spend approx. 7 billion dollars, and the serial production of equipment in the desired quantities required at least 35-40 billion.

Thus, the LHX program and its result in the form of the RAH-66, despite all the advantages and advanced developments, turned out to be too daring for their time and too expensive. The continuation of the project and the immediate use of new technologies in practice was considered inappropriate.

RAH-66 pilot's helmet

Dear groundwork for the future

It should be noted that the developments on the RAH-66 project, which cost billions of dollars, do not seem to be wasted. Right now, the Future Vertical Lift (FVL) program is underway in the United States, the goal of which is to create new helicopters for various purposes. The Comanche influence is noticeable in the design of the demonstrated samples - issues of visibility are taken into account, advanced developments in the field of avionics are used, etc.

It is expected that helicopters of the FVL program will go into production at the turn of the twenties and thirties and then replace several models in service at once. Thus, a failed project of the past may affect the future. Unless, of course, new difficulties arise, as in the past.
Photos used:
US Army,
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  1. OgnennyiKotik
    OgnennyiKotik 10 February 2021 18: 12
    What is the failure? The helicopter was created and met the stated requirements. Dear? Well, what TK, such is the price. Comanche developments allowed the military to understand what they needed, and technology formed the basis of other machines. For example the stealth Black Hawk.
    1. Mark kalendarov
      Mark kalendarov 10 February 2021 18: 28
      I agree! It looks like he was "shot down" already at the Pentagon ...
      1. RealPilot
        RealPilot 10 February 2021 20: 49
        He was not needed. Everything is very commonplace.

        After the end of the Cold War, the need to fight with an equal opponent disappeared, and for the current opponents and the available samples were enough.

        Expensive and unnecessary ... And now the groundwork will come in handy if you set a goal.
        We also have a lot of interesting developments that are now being applied, and are issued for fundamentally new inventions.
        1. yehat2
          yehat2 11 February 2021 09: 55
          Quote: RealPilot
          Expensive and unnecessary

          the fact is that the operation of the Apaches is also not very cheap.
          It seems to me that the Americans did not continue the program in vain.
          I think if they had a pragmatic approach to production, as they did with the F-16 and F-35, they would have received normal results.
          In addition, the absence of the Comanches has forced more investment in UAVs.
    2. Pechkin
      Pechkin 10 February 2021 18: 31
      Stealth black hawk. Interestingly, this machine was generally produced and in which divisions it serves. Really interesting.
      1. OgnennyiKotik
        OgnennyiKotik 10 February 2021 18: 46
        Serves in the most secret, he was used in the murder of Osama bin Laden.
        An article about this helicopter:
      2. Errr
        Errr 10 February 2021 20: 25
        There is very little information on the car shown in the photo from the OgnennyiKotik commentary. In addition to the article on VO dated August 17, 2020 (, about which the aforementioned comrade narrated, I came across only one on address
    3. Cowbra
      Cowbra 10 February 2021 19: 20
      The failure is that "it's better to do it once on time than twice right." We didn’t have time, and when they did it, it wasn’t needed nafig, because it was a breakthrough only for the early period of development. And by the time they completed it, there were already other conditions on the battlefield, and the drones made this helicopter as a standing one - this was already archaic.
      Well, in short, as always - the project flopped down, tempted by advertising. Vparili to the Pentagon, hanging noodles on the ears. They were still lucky that they lost little - only 9,8 billion, it seems? And now I would have to compose fairy tales, like about the F-35, about this is not a failure, but a breakthrough, and the money is not thrown into the wind)))
      1. Nestor Vlakhovski
        Nestor Vlakhovski 10 February 2021 20: 11
        It was later that drones took bread from attack aircraft and combat helicopters. At the time of the 90-00s, they were of little use for large-scale military operations.
        The problem of "Comanche" was initially inadequate terms of reference, because of which the car did not receive significant advantages in comparison with much cheaper and already serial analogues.
        Technologies for reducing thermal and sound masking were subsequently introduced on the notorious Apache, and high radio masking is not so important for an assault vehicle, the main threats to which are various ZU-23, MANPADS and other anti-aircraft complexes with optical-electronic systems.
        1. Cowbra
          Cowbra 10 February 2021 20: 34
          And on what grounds was the technical specification given? It does not happen like this, sitting in the headquarters of ENERAL, suddenly he was flattened in the head - but take out and put a super-helicopter for me, so that it could be invisible, soundless, and embroider with a cross! So someone sang that such a helicopter can be built. So someone sang that we will make a helicopter. So someone took it - and threw 9,8 lard to the wind, without bothering to first check - and whether the cunning uncle-sellers and to them the head of the chainsaw, did not prick the frayer (with - "meeting place ...") 9,8 lard already sawing?
          This is what we are talking about, which is a very characteristic picture for PentaNoga. If they are there so from time to time "wrong", then you must first look for the cause of such errors.
          Get out. on the first picture I wrote, what is the divorce of the pedal sucker! This is not adding that, for example, one helicopter they drew a little bit, and the propeller is an extremity, and the other also has a snobel sticking out for a kilometer. Little things, but it is from them that the divorce of a sucker for grandmother consists. Bottom line, sucker - lit, and it's a fact!
          1. Nestor Vlakhovski
            Nestor Vlakhovski 10 February 2021 21: 00
            The reasons are common to all regular armies.
            1) Due to the existing system of seniority, only hardened careerists, and even exclusively old age, get into the generals. The applied skills of which are no longer relevant for a long time, but there are more than enough official contacts, acquaintances and inertia of thinking.
            2) There is no system of rewards and punishments depending on the effectiveness of action or inaction.
            3) State organizations freely use other people's (state) money, and traditionally spend it as stupidly as possible.
    4. Mikhail3
      Mikhail3 11 February 2021 13: 12
      Quote: OgnennyiKotik
      The helicopter was created and met the stated requirements.

      Yes, he did. True, the requirements have completely changed, and the helicopter is simply not needed. All the functions for which it was created are now performed by unmanned aerial vehicles and missiles directed by them. People have created an exemplary, very advanced cart from the latest materials. And the car is running around with might and main ...
      1. OgnennyiKotik
        OgnennyiKotik 11 February 2021 13: 40
        Quote: Mikhail3
        True, the requirements have changed completely, and the helicopter is simply not needed.

        Quite right, the requirements were written at the height of the Cold War, the USSR collapsed, they completed the project by inertia. The world is already different. In this world, Kamanch has no advantages over Apache.
    5. yehat2
      yehat2 16 March 2021 11: 27
      Quote: OgnennyiKotik
      What is the failure?

      did not get what they wanted and not then
      compliance with the TOR of 82 years, implemented 10 years later, is a failure for military equipment, because in fact aviation will receive a product that was designed 15-20 years ago and is obsolete.
      The I-16 in 40-41 was completely satisfied in terms of compliance with the TK, but technologically too outdated,
      and for some 3-4 years. And here we are talking about 15-20.
  2. aars
    aars 10 February 2021 18: 31
    Does he have an electric tail rotor?
    1. Errr
      Errr 10 February 2021 22: 03
      There is no electric motor in the fenestron. smile
      In the Boeing / Sikorsky RAH-66 Comanche photo below, in the fenestron annular channel, the tail shaft of the tail rotor is clearly visible from the side of the tail boom.
  3. ares1988
    ares1988 10 February 2021 18: 41
    But the series of video games turned out to be quite good.
    1. Klonser
      Klonser 11 February 2021 10: 46
      I flew this)
  4. Cowbra
    Cowbra 10 February 2021 19: 13
    The obvious advantages of stealth: the helicopter finds the enemy before it reveals itself

    How mattresses make me happy. Even in such a small way, they cannot help but lie. LH safe engagement is considered along the line of target - dash - LH itself. And this distance is shorter than indicated in the figure! It’s a pity they didn’t finish placing the target at the very corner of the "LH detect" zone, then one could say that the enemy will never see it at all.
    Actually, such small snares led to a large oser in the end. This is not a supermarket customer STEAMING the Loch Ness Monster Scale baldness remedy
  5. Sergey Fomenko
    Sergey Fomenko 10 February 2021 19: 28
    It's crazy about thermal insulation, but where does the excess heat go?
    1. Nestor Vlakhovski
      Nestor Vlakhovski 10 February 2021 20: 16
      Exhaust gases are cooled inside the tail boom and discharged at the very tail of the vehicle, a similar solution used in the new S-97.
      1. Sergey Fomenko
        Sergey Fomenko 14 February 2021 09: 44
        That is, the tail boom glows in the ir range like a beacon, or are you talking about unparalleled technology ...
        1. Nestor Vlakhovski
          Nestor Vlakhovski 15 February 2021 01: 43
          or are you talking about unparalleled technology
          if ordinary shielding and thermal insulation materials are considered "unmatched technologies", then I have bad news for you. The school physics program has gone deafeningly.
          1. Sergey Fomenko
            Sergey Fomenko 15 February 2021 13: 50
            And the fact that the screen warms up and, unlike the exhaust gases, is bolted to a helicopter, the great physicist is not aware of ...
            1. Nestor Vlakhovski
              Nestor Vlakhovski 15 February 2021 14: 09
              Let it warm up as much as you like, for this you need a screen, the main thing is that the skin of the helicopter has an ambient temperature. The exhaust gases also mix with the forced air and, at the outlet, are already significantly less heat-contrast.
  6. Niko
    Niko 10 February 2021 20: 59
    It's good when people have enough money for such projects. Even if yesterday it looks like an unreasonable dream, tomorrow it becomes a groundwork for the implementation of developments.
  7. Monar
    Monar 11 February 2021 09: 10
    Absolutely not an armored vehicle. From the word at all.
    special blade design
    What is this? Angled tip? Well, that's understandable. There speed claims to be supersonic. The Ka-50 is the same.
    But I liked it at all
    It was also possible to reduce the propeller speed to reduce noise. Similar ideas were implemented on the tail rotor.
    What is this, excuse me, for nonsense? Of course, I apologize wildly, but is it impossible to reduce the gas step in any helicopter?
  8. yehat2
    yehat2 11 February 2021 10: 00
    Quote: Cowbra
    TK on what grounds was given? It does not happen like this, he is sitting in the headquarters of ENERAL, suddenly he was flattened in the head - but take out and put a super-helicopter for me, so that invisible, soundless, and also embroider with a cross

    at the time of setting the technical assignment, the Americans had already developed several stealth aircraft,
    the ATF program was in full swing, which eventually led to the f-22 and f-35.
  9. yehat2
    yehat2 11 February 2021 10: 04
    Quote: Nestor Vlahovski
    Exhaust gases are cooled inside the tail boom and discharged at the very tail of the vehicle, a similar solution used in the new S-97.

    in the IR range, contrast and brightness are important.
    If the same hot gas is mixed with normal gas and sprayed over a large area, the difference with the background can be significantly reduced.
    The Americans are trying to use this even on tanks.
  10. voyaka uh
    voyaka uh 11 February 2021 16: 24
    Correctly closed.
    The era of drones began.
    And above all - reconnaissance drones.
    Kamikaze helicopter pilots are not needed for reconnaissance.
  11. 3danimal
    3danimal 12 February 2021 05: 53
    A very interesting helicopter.
    One of the first models that I assembled as a schoolboy (after Ka-50) smile
  12. Zaurbek
    Zaurbek 12 February 2021 08: 27
    It is trite - measures to reduce noise will find application on commercial helicopters ... And this is how we see the concepts of promising helicopters and there Comanche is clearly visible.
    1. 3danimal
      3danimal 12 February 2021 15: 12
      They are used on the Apache. “When he is a kilometer away from you, you can hardly hear him” (met in the book “Apache” by Ed Macy).
  13. Incvizitor
    Incvizitor 25 February 2021 17: 54
    They wanted to put all the new developments in one machine and at the same time ensure invisibility, in the end, nothing really worked and for the price of platinum ... Something he is straight in all the f 35 reminds.
  14. TerraSandera
    TerraSandera April 11 2021 11: 13
    A very good machine, judging by what was written. But I didn’t understand why the more archaic Apaches were “no worse”. The only question is the price and, accordingly, mass character? Or is this machine just "stealth" with reduced impact characteristics, and they thought and decided that more missiles are better than ephemeral low visibility?