Technical features of the unmanned aerial vehicle Lockheed D-21

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D-21A on a transport trolley. Photo by US Air Force

In the early sixties, the CIA and the US Air Force ordered Lockheed to develop and build a promising high performance reconnaissance unmanned aerial vehicle. The task was successfully solved within the framework of the D-21 project, based on the most daring decisions and ideas. The technical and technological part of this project is still of great interest.

A special challenge


On May 1, 1960, the Soviet air defense successfully shot down an American U-2 aircraft and thereby showed that such equipment could no longer work on the USSR with impunity. In this regard, the search for alternative solutions began in the United States. Lockheed's secret department, known as the Skunk Works, soon came up with the concept of a disposable high-speed reconnaissance UAV capable of photographic reconnaissance.



The proposed idea interested the customers, and in October 1962 there was an official order for the preliminary study of the project. In the shortest possible time, it was possible to complete the formation of the general appearance and begin aerodynamic tests. Based on the results of the first successes, in March 1963 a full-fledged design contract was signed. At that time, the future drone bore the designation Q-21. It was later renamed D-21.

Technical features of the unmanned aerial vehicle Lockheed D-21
UAV airframe at the stage of assembly, internal elements are visible. Photo Testpilot.ru

The first version of the project, known as the D-21A, proposed the use of a UAV with an M-21-type carrier aircraft. The latter was a two-seat modification of the A-12 reconnaissance aircraft with a pylon between the keels and some other devices for working with UAVs. In December 1964, an experienced M-21 made its first export flight with a D-21 on board.

On March 5, 1966, the first launch took place drone from a carrier aircraft. Despite certain difficulties and risks, the separation and the start of an independent flight went without problems. Subsequently, several more such tests were carried out. On July 30, the fourth launch ended in an accident. The UAV could not move away from the carrier and hit its tail section. Both cars collapsed and fell. The pilots ejected, but one of them could not be saved.

Based on the test results of the experimental complex, it was decided to abandon the carrier in the form of the M-21. The updated D-21B reconnaissance project proposed launching from under the wing of a B-52H bomber. The initial acceleration of the drone was to be carried out using a solid propellant booster. Tests of such a complex began in the fall of 1967, but the first successful launch took place only in June 1968.


Combustion chamber and nozzle of a ramjet engine. Photo Testpilot.ru

Trials 1968-69 proved the high characteristics of the new reconnaissance complex. Thanks to this, a large order appeared for serial equipment for the further operation of the Air Force and the CIA. In November 1969, the first "combat" flight took place to shoot a real object of a potential enemy.

Technological base


The D-21A / B UAV could reach a maximum speed of M = 3,35 at an altitude of about 3600 km / h. At the same time, he was able to automatically fly along a given route, go to the area of ​​the designated target and take photographs of it. Then the drone lay down on a return course, dropped a container with reconnaissance equipment in the desired area and self-destructed.

The development of an aircraft with such characteristics and capabilities at that time was very difficult. However, the set tasks were solved through the use of the most modern materials and technologies. Some ideas and developments were borrowed from existing projects, while others had to be created from scratch. In a number of cases, it was necessary to take a noticeable technical risk, which entailed new difficulties.


Carrier aircraft M-21 with UAV D-21A. Photo by CIA

One of the main tasks of the Q-21 / D-21 project was the creation of a glider capable of providing a long flight at speeds over 3M. Such a design had to have the required aerodynamic characteristics, as well as withstand high mechanical and thermal loads. When developing such a glider, the experience of the A-12 project was used. In addition, some design solutions and materials were borrowed.

The D-21 received a cylindrical fuselage with a frontal air intake fitted with a tapered central body. Externally and in its design, the fuselage was similar to the nacelle of the A-12 aircraft. The glider was equipped with a "double delta" wing with a triangular main part and developed long bends. A similar scheme has already been tested in a full-size aircraft project and has shown compliance with the basic requirements.

The airframe of such shapes was proposed to be made entirely of titanium. Other metals were used only as part of other systems and assemblies. The outer and inner surfaces of the airframe, in contact with hot air, received a special ferrite coating, also taken from the A-12 project.


B-52H with a pair of D-21Bs. Photo by US Air Force

Initially, the possibility of using the Pratt & Whitney J58 engine developed for the A-12 was considered, but this led to an unacceptable increase in the cost of the project. An alternative was found in the form of the RJ43-MA-11 ramjet engine from Marquard Corp. - This product was used on the CIM-10 Bomarc anti-aircraft missile. For the D-21, it was modified: the updated RJ43-MA20S-4 engine was distinguished by an increased operating time, which corresponded to the profile of the reconnaissance flight.

A new automatic control system was developed specifically for the D-21, capable of guiding the UAV along a given route. It used inertial navigation devices borrowed from the A-12. Due to the complexity and high cost, the control system was made salvable.

A drop container called Q-bay with a parachute system and inflatable floats was provided in the nose of the fuselage. Inside this container were placed the control system and navigation equipment, as well as all cameras with film cassettes. At the final stage of flight, D-21A / B had to drop a container, which was then picked up by an airplane in the air or by a ship from the water. The search for Q-bay was carried out using a built-in radio beacon. Previously, similar technologies were used to search and rescue film containers launched from reconnaissance satellites.


D-21B under the wing. Photo by US Air Force

Practice check


The first D-21 drones were built in 1963-64, and small-scale production soon began. Before stopping it in 1971, Lockheed had produced 38 products in two main modifications. Some of these UAVs were used in tests and in real reconnaissance flights.

At the first stage of the project, in 1964-66. there were five sorties of the M-21 aircraft with the D-21A UAV on the pylon. Of these, four provided for the reset of the apparatus - three were successful, and the last ended in disaster. Tests of the D-21B lasted from 1967 to 1970, during which time they carried out 13 flights, incl. with imitation of the solution of reconnaissance tasks.

Combat use included only four flights. The first of them took place on November 9, 1969 and ended abnormally. The UAV D-21B successfully reached the Chinese training ground Lop Nor, took photographs - and did not go back. He continued his flight, ran out of fuel and, with some damage, "sat down" on the territory of the Kazakh USSR, where he was discovered by the Soviet military.


Initial acceleration of the UAV using an accelerator. Photo by US Air Force

On December 16, 1970, the second launch took place for reconnaissance of Chinese objects. The UAV successfully completed the survey, returned to the specified area and dropped the Q-bay container. It was not possible to catch it in the air, and the rise from the water failed - the product, along with the equipment and films, sank. The third flight on March 4, 1971 ended with similar results, the container was lost.

The last flight of the D-21B took place a few weeks later, on March 20. The device, for unknown reasons, fell on the territory of the PRC, not far from the landfill to which it was heading. After this failure, the CIA and the Air Force were finally disillusioned with the D-21B project and decided to stop using such equipment.

Considering the results of the tests and actual use of the D-21A / B, you can see the main reasons for the failure. Thus, the lack of reliability of the control system became a serious problem. In particular, it is for this reason that the secret UAV after the very first "combat" sortie went to a potential enemy. In addition, unexpected problems arose with the search and rescue of the container with the equipment - however, the drone's own fault in this was minimal.


The wreckage of the fourth "combat" D-21B in the Chinese Museum. Photo Wikimedia Commons

With all this, the D-21A / B UAV was technically complex and expensive. The average cost of each such product, taking into account the development work, reached 5,5 million dollars in 1970 prices - about 40 million today. It should be noted that the cost of a single drone was significantly reduced due to the repeated use of a container with the most expensive components.

Limited potential


The designers at Lockheed / Skunk Works were given a very difficult task, and they generally coped with it. The resulting reconnaissance apparatus showed the highest tactical and technical characteristics, but still did not fully meet the requirements of real operation. The D-21 product turned out to be too complex, expensive and unreliable.

Perhaps further refinement of the design would have eliminated the identified problems, but it was abandoned. In addition, they abandoned the concept of a supersonic long-range unmanned reconnaissance aircraft. As a result, bold and promising technical solutions, despite their high potential, did not find further application.
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15 comments
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  1. +3
    July 10 2021
    Familiar pictures, somewhere I've already seen them ...
    And here on VO I saw:

    https://topwar.ru/162891-amerikanskij-drozd-sovetskomu-voronu-ne-tovarisch.html
    https://topwar.ru/162891-amerikanskij-drozd-sovetskomu-voronu-ne-tovarisch.html
    There are even more pictures.
    And the text is somehow more substantiated.
    And the author is Ryabov Kiril. It turns out he knows how.
    1. +2
      July 10 2021
      Oh, okay, apparently there are not enough VO authors, summer is the same.
      Here is a video material that deserves more attention. He had a series about A-12 / YF-12 / D-21. Very interesting.
      1. +6
        July 10 2021
        Quote: OgnennyiKotik
        Oh, okay, apparently there are not enough VO authors, summer is the same.

        Summer is summer, but the author is a friend. after all came across the material. I was able to read it, made a summary of it, and briefly conveyed to us what we knew even before the era of the Internet. Fair? Even too lazy to look, in their paper bins, a monograph of the late 80s, dedicated to the SR-71 family and everything accompanying it.Laziness. And for those who enthusiastically begin to praise this article - how great, how much I learned, did not know much - I will google to help, to close the gaps in knowledge ... laughing laughing good drinks
        1. 0
          July 12 2021
          and I was not lazy, I looked for a paper carrier. publishing house AST.Moscow. 2001. "black lightning SR-71". series Famous aircraft. I recommend to anyone interested.
          1. 0
            July 13 2021
            Quote: vadivm59
            and I was not lazy, I looked for a paper carrier. publishing house AST.Moscow. 2001. "black lightning SR-71". series Famous aircraft. I recommend to anyone interested.

            Yes, this is that magazine, well, besides that, there are still some interesting articles and monographs. I collected them when I was thinking of "building" the SR-71 model, well, then I looked at the "congestion" of the shelves. and decided to stop at Soviet reagents + planes of the Great Patriotic War ...
  2. +6
    July 10 2021
    Satellites have buried most types of strategic air reconnaissance.
  3. +1
    July 11 2021
    > Perhaps further refinement of the design would have allowed to get rid of the identified problems, but it was abandoned.

    Perhaps equipping with a landing system, because the very idea of ​​such an expensive disposable machine is quite delusional.
  4. 0
    July 26 2021
    Quote: Lontus
    Satellites have buried most types of strategic air reconnaissance.
    This one was not buried. Let's see the width of the shooting zone and the time spent in the zone.
  5. 0
    July 26 2021
    I don’t know why the USAF didn’t make it out of a UAV. hypersonic CD.
  6. 0
    12 September 2021
    Quote: 9lvariag
    I don’t know why the USAF didn’t make it out of a UAV. hypersonic CD.

    Because the lower limit of the hypersonic speed is usually associated with the onset of the processes of ionization and dissociation of molecules in the boundary layer near the apparatus, which moves in the atmosphere, which begins to occur approximately at M> 5, to which the drone with its M = 3.35 does not reach.
    1. 0
      13 September 2022
      Quote: FreeDIM
      Quote: 9lvariag
      I don’t know why the USAF didn’t make it out of a UAV. hypersonic CD.

      Because the lower limit of the hypersonic speed is usually associated with the onset of the processes of ionization and dissociation of molecules in the boundary layer near the apparatus, which moves in the atmosphere, which begins to occur approximately at M> 5, to which the drone with its M = 3.35 does not reach.

      1. Do you even know what times you grind? And in what years finally this classification was rewritten in the West to please the conjuncture of the military-industrial complex and PR?! I take it you weren't even born in the 1980s.
      2. I understand that you are a humanist? We decided to flash a finger at the sky and did not know that the speed of sound decreases with height, and the so-called. Is the Barstow-Mach number going up? So, not 3,35, but M = 3,45 for a height of 11 km. on which the GTD-21D NEVER flew from the word at all! And he flew at an altitude of 23 km., And at this altitude only Tiocoll solid propellant booster was launched /
      3.A from now on in more detail. I hope you tell me the temperature of the nose cooker of an aircraft (type X-15) capable of withstanding 5M of the troposphere? Do you remember one astronaut repeating your trick with a hypersonic corkscrew at this KCO? This is for the first generation "hot type" ECC with curtain cooling. like the X-15.
  7. 0
    13 September 2021
    Quote: Fitter65
    Quote: OgnennyiKotik
    Oh, okay, apparently there are not enough VO authors, summer is the same.

    Summer is summer, but the author is a friend. after all came across the material. I was able to read it, made a summary of it, and briefly conveyed to us what we knew even before the era of the Internet. Fair? Even too lazy to look, in their paper bins, a monograph of the late 80s, dedicated to the SR-71 family and everything accompanying it.Laziness. And for those who enthusiastically begin to praise this article - how great, how much I learned, did not know much - I will google to help, to close the gaps in knowledge ... laughing laughing good drinks

    You knew and some didn't. Someone does not want to read monographs, a short article is enough.
    Or would you like the authors of the site to sit in the archives and find some sensation over the years of painstaking work ??? But not bad, of course, even great. But the site was not created for this, to print monographs. Yes, and monographs (most) in Russian about imported aircraft were written based on materials from foreign press, books, etc. T e, too, did not open anything new (except for Russian-speaking readers). Of course, this is an important and painstaking work, and many thanks to the authors for this.
    Just in the end I want to say in defense of the author of the article "VO". It is normal for a website to write small articles based on materials from previously published literature and press. After all, most readers do not want to read a bunch of specialized literature (this is only for specialists and those who are especially interested in details, but such a minority). And here is a small article that is interesting for the general reader. This also requires knowledge, the ability to find what is important and meaningful.
    For example, I like to read about aviation in as much detail as possible, and even monographs are few for me, but there I don't need such details about tanks, ships, etc., short high-quality articles are enough for me. A person cannot be very deeply interested in everything. Therefore, do not judge the author of the article too harshly.
  8. 0
    16 September 2021
    The car is interesting in all matters, if it had been finalized, it would have brought us a lot of trouble,
    Americans have their own engineering school and not the worst, it is good that they sintered in their time.
  9. +1
    October 4 2021
    "Sat down" on the territory of the Kazakh USSR

    Probably more correct than the Kazakh SSR with two letters "C" ...
  10. 0
    October 25 2021
    On May 1, 1960, Soviet air defense successfully shot down an American U-2 aircraft.
    "Successfully shot down" from the 12th rocket in the process by shooting down her own interceptor (the pilot was killed)

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