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A tiltrotor that is capable of level flight like an airplane, while still being able to hover, take off and land vertically like a helicopter. For a long time, designers have been embarrassed by their attractive prospect, to increase speed compared to a helicopter and, at the same time, not to depend on the availability of airfields like an airplane.
And by the end of the 1920s of the last century, design thought began to boil.
The work unfolded in two directions - the creation of devices with rotary propellers and devices with a rotary wing.
In particular, in 1922, the American inventor Henry Berliner, based on the Newport 23 fighter airframe, built an aircraft equipped with two counter-rotating propellers and one variable-pitch propeller with a diameter of 30 cm. The propellers were driven by a Bentley BR-rotary engine. 2 with a capacity of 220 liters. with., installed in the forward fuselage. The large propellers provided a helicopter-like flight, and the small one allowed the pilot to slightly tilt the nose of the machine - as a result of this, the large propellers also tilted slightly forward and ensured an airplane-like flight. Later, the designer converted the biplane into a triplane (this device is known under the designation "Model 1924" and also differs in the location of tilting propellers in the middle part of the triplane box), but he failed to provide an acceptable lift - the device rose a maximum of 15 feet (4 .6 meters).

Biplane designed by American Henry Berliner

Based on the experience gained, G. Berliner in 1925 built an apparatus that generally resembled a biplane, but equipped with two large-diameter propellers installed in the wing tips and partially tilted forward, thus allowing it to fly both in a helicopter and and by plane. Berliner managed to develop a flight speed of about 40 miles per hour (about 70 km / h) on his apparatus, but he did not succeed in significantly increasing the flight altitude. However, according to eyewitnesses, the propellers did not lean forward completely - only at a certain angle, which allowed the device to move forward, and therefore aviation historians call this device a “helicopter with rotary screws”. In general, the concept of the aircraft of G. Berliner is similar to modern convertiplanes.
On September 16, 1930, George Leberger, who lived in County County, New Jersey, received US patent No. 1775861 for an aircraft project, which can be considered the first version of a tiltrotor, the ancestor of this family. The device, called in the patent simply and uncomplicatedly “flying machine” (“Flying Machine”), was equipped with two coaxial propellers of different diameters installed above the fuselage in the bow, which could be installed in vertical (helicopter-like) or horizontal (aircraft-like) planes.
However, he did not go further than a patent. As well as the British aircraft designer Leslie Baines, a well-known glider designer who designed the Singapore and Calcutta flying boats by order of the Short company in the 1920s and is the author of the first patent for an aircraft with a variable sweep wing (1949). In 1938, he received a patent for the so-called "helicopter", which was an aircraft-type aircraft, on the end parts of the wing of which there were engine nacelles that could be installed vertically - for helicopter flight or horizontally propellers forward - for airplane flight. For the practical implementation of his idea, Baines did not have enough money.

"Helicopter" by Leslie Baines

The situation was more successful with the German aircraft designers. Since 1942, the Focke-Ahgelis specialists have been developing here the Fa 269 mixed design fighter - a tiltrotor with rotary screws. The company was founded on April 27, 1937 by the famous German aircraft designer Heinrich Focke and the German pilot Gerd Akhgelis, no less famous in those years, with the aim of developing and building helicopters and gyroplanes. The most famous of them was the Fw 61, which made its first flight on June 26, 1936 and in subsequent years set a number of records for altitude, speed and flight range for machines of its class.
The Fa 269 was developed under the guidance of engineer Paul Klage with the aim of integrating the advantages of a helicopter capable of taking off and landing vertically, and an aircraft with higher speed and better fuel efficiency in one device. At the same time, work on this topic was not started from scratch. Back in 1938, engineer Simon, at the direction of Adolf Rohrbach, technical director of the Weser Flygzugbau G. m.b.H. in Lemwerder, near Bremen, began the design of a single-seat aircraft with a rotary wing, designated WP 1003/1. Rohrbach, an engineer by education, since 1933 independently studied the possibilities of creating a tiltrotor, and having received the plant and its design bureau at his disposal, he decided to try to put this idea into practice.
WP 1003 / 1 was a monoplane with an average location of a trapezoidal rotary wing - the outer halves of its consoles turned with tractor propellers with a diameter of 4 meters located in their end parts. The propellers could turn down almost 90 degrees. A 900 hp engine housed in the fuselage. With. was supposed to provide the tiltrotor with a maximum horizontal flight speed of about 650 km / h. The pilot's cockpit was shifted forward and had a sufficiently large area of glazing, which provided a good overview for the pilot.
As for the Fa 269, it was structurally a mid-wing monoplane with a small sweep along the leading edge, in the middle part of which were located two pushing three-blade propellers of very large diameter. If it was necessary to switch from airplane mode to helicopter mode, the propellers turned down at an angle of up to 85 degrees, this was mainly supposed to be done during takeoff and landing. BMW 801 air-cooled radial engine with 1800 hp. With. located in the fuselage, behind the cockpit, and worked on propellers using a special transmission. Moreover, the developers were required to use the main landing gear with long struts on the machine, as well as the tail landing gear with a sufficiently high strut that retracted into the fuselage - in order to avoid damage to the propellers on the ground (runway). The crew - one, according to other sources, two people, was located in a fairly spacious cockpit, shifted forward and had a large glass area, including for a better downward-forward view. Armament - two 30-mm guns MK 103 or MK 108 - were located on the sides of the cabin. It also provided for the possibility of placing a 20-mm gun MG 151/20 in a special gondola under the fuselage. The avionics included radio stations FuG 17 and FuG 25 a, the possibility of installing a radio altimeter was studied - to perform a "blind" flight.
The terms of reference for the new “wonder weapon” were issued by the German Ministry of Aviation to the Focke-Ahgelis company back in 1941. The military needed a single-seat "local defense fighter". However, according to other sources, the work was purely initiative in nature, but was favorably received by the military. The development of the tiltrotor was completed in 1942, a scale model was blown in a wind tunnel, and a full-size model was soon built. The main advantage of the tiltrotor fighter was considered unpretentious in terms of basing and prompt action against Allied bomber aircraft, which had already gotten to the German military-political leadership. However, after the mock-up and all project documentation were destroyed during the next allied air raid on the night of June 3-4, 1942, work on the program began to fade, and in 1944 the project was completely closed. The main reasons for the failure are the lack of funds and time (according to the calculations of the specialists of the developer company, a prototype at such a pace could be built no earlier than 1947), as well as the lack of special gearboxes, drives, various mechanisms and equipment required for the machine. It remains to be added that in 1955 an article was published in the British magazine Flight, which reported: in the United States, Professor Fokke received a patent for a tiltrotor project "developed in the interests of the Brazilian government." More detailed information on this project was not contained.

The United States steps in

Work in the field of convertible aircraft did not go unnoticed by the opponents of the Third Reich, especially since the bulk of the documents on German developments and the surviving engineers and designers fell into the hands of the Americans and the British - the former weapons creators did not seek to surrender to the Russians. Moreover, they began to adopt the experience of German engineers in the West in the early 1940s.
Among those who decided to take advantage of the experience of German helicopter builders were Dr. Wynn Lawrence Le Page and Haviland Hull Platt, founders of the Platt-Le Page Aircraft Company of Addystone, Pennsylvania. Taking the design of the German Fw-61 helicopter as a basis, the Americans in 1941 designed the XR-1 A twin-rotor helicopter. The latter, in turn, served as a reference point for creating an outwardly similar tiltrotor with a take-off weight of 24 tons. The fundamental difference was that its propellers could turn, leaning forward, and provide the car with an airplane-like flight. Moreover, despite the fact that this tiltrotor was not implemented in hardware or at least in a full-size layout (it did not even have its own name), the work was not in vain - on December 15, 1955, H. X. Platt received a US patent for No. 2702168 .

Convertiplane Le Page - Platte

The next attempt to successfully "cross" a helicopter and an airplane was made in early 1947 by specialists from the Transcendental Aircraft Corporation of Newcastle, Delaware. This time, the aircraft designers managed to create a truly efficient aircraft, which managed to take to the air and, on the whole, confirmed the correctness of the chosen technical solutions.
This project was initiated and driven by the founders of Transcendental, Mario A. Guerieri and Robert L. Lichten, who previously worked together at the Kellett Aircraft Company. Moreover, Lichten had previously worked with American helicopter designers - Le Page and Platt mentioned above - and became an active supporter of the tiltrotor concept, and while working at Kellett, Guerieri joined him. Together they conducted a significant amount of research to find out how effectively the main rotor used in helicopters can be used in the version of the "aircraft" propeller.
The results obtained in the course of these works added to Lichten and Guerieri the confidence that they are on the right track and their idea is not so fantastic. Like-minded people decided that now they need to independently develop, build and lift into the air, proving its ability to fly, a small single-seat experimental tiltrotor, designated "Model 1-G".

The world's first flying tiltrotor "Model 1-G"

A distinctive feature of the machine, which had a maximum length of 7.93 meters and a takeoff weight of about 800 kg, was the presence of only one piston engine - it was located inside the fuselage and worked on both three-blade counter-rotating propellers (screw diameter - 5.18 m) located in end parts of the wing with a span of 6.4 meters.
The maximum power of the Lycoming O-290-A four-cylinder engine, located in the fuselage directly behind the cockpit, reached 160 hp. with., at 3000 rpm. The maximum flight speed in airplane mode is 256 km / h (propellers - no more than 633 rpm), in helicopter mode - 196 km / h (no more than 240 rpm). The transition from one mode to another took no more than 3 minutes, while the screws could rotate within 82 degrees. The fuel supply allowed to be in the air for up to 1.5 hours.
The first tiltrotor built by the company collapsed during ground static tests in 1950, but the second, which is known under the designation "Model 1-G", was initially considered by the developer only as a ground test vehicle and only after receiving a government contract was modified for the program flight tests.
The first tiltrotor in the world went on its first flight on June 15, 1954, but only five months later its creators risked switching from one flight mode to another. By that time, both founders of the company had already left it. Lichten in 1948, and Guerieri in September 1952, sold his share to William E. Coby, who worked as a diagnostic specialist for the Kellett Aircraft Corporation. Moreover, Kobe managed to secure financial support - albeit small - from the US Department of Defense. In fiscal year 1952, the Army and Air Force ministries signed a contract with the company, according to which customers were to receive all the results of flight tests of the new machine. A similar contract was signed with the US Air Force the following year, 1953.
However, having made a little more than 100 flights with a total duration of 60 hours, during which, however, a complete transition to the airplane mode was never completed, on July 20, 1955, the tiltrotor lost control and crashed while flying in the airplane mode. in the waters of the Chesapeake Bay. The accident occurred near the coast, in shallow water, and the pilot managed to escape. The device, of course, had to be written off.
Nevertheless, the possibility of creating an aircraft of a new class was confirmed in practice, and the company began building the second prototype tiltrotor - Model 2. It was already a two-seater, with pilots landing side by side, had a take-off weight of 1020 kg, a shorter fuselage by 1.2 meters and a wing span that was 0.3 meters smaller. It was powered by a One Lycoming O-435-23 six-cylinder engine producing 250 hp. with., and the payload reached 304 kg.

Convertiplane "Model 2"

However, the US Air Force pulled out of the project. The preference for the military was given to the alternative apparatus XV-3, developed by Bell, and it was impossible to fully implement the test program at its own expense. As a result, the tiltrotor "Model 2" managed to make only a few short-term flights in helicopter mode. The program was finally closed in 1957.

Famous "Pentecostals"

During the 1950s, a number of tiltrotor projects were developed in some other companies, but the vast majority of them did not even take to the air. However, there were quite remarkable projects among this host of developments, which are worth briefly dwelling on.
In the 1940s and 1950s, the US military showed an active interest in vertical or short takeoff and landing aircraft, thanks in part to information about equally active work being carried out in the Third Reich. One of the companies engaged in work in this area was Vertol Erkraft (formerly Piasecki), which developed the Model 76 aircraft on its own initiative. In 1960, this company was acquired by the Boeing concern and became its helicopter division Boeing Vertol.
A distinctive feature of the new machine was that it was the first in the world to successfully implement the technical idea of a rotary wing. Previously, such machines were called rotorcraft, but they can also be classified as "tiltiplanes". Structurally, the device, which later received the name VZ-2, was a monoplane with a high wing installed in its central part, with an open truss fuselage and a tricycle landing gear with a nose strut and a tail wheel. It had a cockpit with a spherical canopy from a Bell 47 helicopter, behind which was an Avco Lycoming YT53-L-1 gas turbine engine and transmission.

Convertiplane VZ-2

The wing, rectangular in plan, had an all-metal structure and was attached to the fuselage on hinges and, under the action of hydraulic power cylinders, could rotate 90 degrees. Takeoff in a helicopter was carried out by turning the wing and three-blade propellers vertically upwards, and after reaching a safe height, the pilot returned it to its normal position - the device switched to airplane mode. The tail unit is T-shaped, with a large keel. At the same time, for more efficient control when flying at low speeds, additional propellers of small diameter were placed in the tail section of the VZ-2.
Experimental car, sir. No. 56–6943, flown in April 1957. The first successful transition from one mode to another - in horizontal flight - was made on July 23, 1958. Even before that, the development company signed a contract with the US Army and Navy ministries, which allocated 850 thousand dollars for the completion of the device, which received the new designation VZ-2 A. Flight tests were initially carried out by the development company, together with specialists from the US Army and the NASA aerospace agency, but in the 1960s the project was completely transferred to the latter. The S.P. Langley Research Center operated the VZ-2A until 1965. During the operation of the apparatus, about 450 flights and 34 complete transitions from one mode to another were performed. The device is currently on display at the Smithsonian Institution.

Convertiplane VZ-2

Another interesting project was the tiltrotor, developed in 1959 in cooperation with Vertol specialists and the NASA agency. It did not receive any name of its own and is simply referred to as a device with a rotary wing developed by Vertol - NASA (Vertol-NASA Tilt-Wing). Its distinctive feature was a rotary wing, on which there were six propellers, which were supposed to be driven by a 1000 hp motor. with., as well as double-slotted ailerons, which occupied up to 60% of the length of the trailing edge of the wing. Work on the project, however, did not go further than blowing a scale model in a wind tunnel.
A completely different concept of "merging an airplane and a helicopter" was worked out by American aircraft designers on the tiltrotor VZ-4. Its development was carried out in the second half of the 1950s by the Doak Aircraft Company of Torrance, California. This apparatus had rotary propellers in the annular nozzles (channels). The reason for choosing this design option was simple - the president of the development company, Edmond R. Doak, was engaged in work in the field of propellers located in annular channels.

VZ-4 at the US Army Museum, Fort Estis

E. R. Doak first sent his proposal to the military in 1950, but it was not until April 10, 1956 that the US Department of the Army, represented by the Transportation Engineering Research Command, signed a contract with him. The following year, the company began active work on the device, which at first received the in-house designation "Doak 16". Its first flight took place on February 25, 1958 (serial number 56–9642). Subsequently, the tiltrotor was renamed the VZ-4 DA, structurally it was a small experimental medium wing with a pilot cabin with a tandem landing of two people (pilot and observer), with a traditional tail and a fixed tricycle landing gear with a nose strut. The tiltrotor fuselage was made of welded pipes, the skin from the nose to the pilot's cockpit was composite (molded fiberglass), and from the cockpit to the tail it was aluminum. Cantilever wing and tail - all-metal.
The main distinguishing feature of the Doak 16, equipped with one Lycoming T53-L-1 turboshaft engine with an 825 horsepower. with., there was the presence of rotary propellers in the annular channels (nozzles) located in the end parts of the wing planes. The propellers could turn forward 90 degrees to perform horizontal flight, and also deviate back 2 degrees from the vertical - when operating in the "helicopter" mode.
In order to minimize the cost of designing and building a tiltrotor, Doak decided to make the most of the developments of other aircraft manufacturers and structural elements from other aircraft. In particular, the landing gear was borrowed from the Cessna-182, the crew seats from the F-51 Mustang, the drives for turning the propellers in the annular channels from the electric motors for the flap drive of the T-33 trainer, and the rudder from an earlier aircraft. development "Doak".
The tiltrotor "Doak 16" was built in a single copy (serial number 56–9642). Its estimated empty weight was 900 kg, and the maximum take-off during vertical take-off was 1170 kg, however, in the process of finalizing the machine, these figures increased to 1037 kg and 1443 kg, respectively. The maximum speed, according to calculations, was to be at least 370 km / h in horizontal flight, the rate of climb at sea level was 30 m / s, the service ceiling was 1830 m, the flight duration was about 1 hour, and the maximum flight range was 370 km.
Ground tests of "Doak 16" took place on the territory of Torrance Municipal Airport in February 1958, 32 hours on the stand and 18 hours of "tethered approaches" and taxi tests. On February 25, the first free flight was made. In June, the tests in Torrance were completed, and the tiltrotor underwent a thorough study, after which it was transferred to Edwards Air Force Base in October, where it underwent a 50-hour test, in which the transition from one mode to another was repeatedly performed - including number at an altitude of 1830 meters.
After the completion of the tests, the US Army in September 1959 accepted the tiltrotor, assigning it the designation VZ-4, and transferred it to the Langley Research Center, owned by NASA, for new tests. In the course of the latter, not only the advantages, but also a number of disadvantages of this scheme were revealed. One of the most significant was the tendency of the device to turn up its nose during the transition between helicopter and airplane modes. It turned out to be worse than expectations and take-off and landing characteristics. During the tests, the tiltrotor was able to develop a speed of 370 km / h, the maximum rate of climb was 20 m / s, and the flight range was 370 km.
In the late 1960s, the development company entered a period of financial failure and sold the rights and all the technical documentation for the VZ-4 tiltrotor company Douglas Aircraft, located nearby, in Long Beach. But this did not help either - in 1961, the Doak company ceased to exist. Douglas, meanwhile, completed a preliminary study of the modernization of the unexpectedly received tiltrotor, including the installation of a more powerful engine, and in 1961 sent a proposal to the US Army command. However, there was no answer. The tiltrotor itself operated at the Langley Center until August 1972 and then was transferred to the US Army Transportation Service Museum at Fort Estis, near Newport News, where it is today.
Another American experimental convertoplane with a rotary wing was the X-18, developed by Hiller under a contract with the US Air Force dated February 1957. The contract, worth 4 million dollars, provided for the development, testing of a tiltrotor, as well as the construction of 10 machines. The company also managed to get a contract for similar work from the US Navy - the admirals needed a tiltrotor capable of taking cargo weighing up to 4 tons. During the construction process, individual structural elements from other aircraft were actively used. In particular, the fuselage was a slightly modified fuselage from Chase's XC-122C, while other elements were from Conware's R3 Y Tradewind military flying boat.

X-18 convertoplanes

The X-18 had a rectangular fuselage with a high wing of small span, in the middle part of which two powerful 5500 hp winglets were installed. With. Allison T40-A-14 turboprop engines with Curtis-Wright three-blade counter-rotating turbo-electric propellers (diameter 4.8 meters). Moreover, during takeoff in a helicopter, the entire wing turned along with the engines (around its longitudinal axis at an angle of up to 90 degrees), although takeoff in an airplane was used for takeoff with a maximum payload. In addition, in the tail section of the machine there was an additional Westinghouse J-34-WE turbojet engine with a thrust of 1530 kgf (15.1 kN), the jet stream of which could be deflected in a vertical plane, which improved the controllability of the machine at low speeds.
In 1958, the first, and as it turned out, the only prototype was built, which went through an intensive cycle of ground tests and in 1959 was transferred to the Langley Research Center, where on November 24, 1959 it performed its first free flight. Before the completion of flight tests in July 1961, the tiltrotor managed to make 20 flights. The main reason for the completion of the test and the subsequent closure of the program was a malfunction in the propeller pitch change mechanism that occurred on the last flight, and the fact that the engines "were not interconnected." However, he still made it possible to collect a sufficient amount of data necessary for the construction of a heavier tiltrotor - the four-engine XC-142. During one of the ground tests - after the completion of the flights, the X-18 tiltrotor was destroyed and ended its days in a landfill.

XC-142A at the National Museum of the United States Air Force

As for the XC-142, it was developed jointly with the Vought and Ryan companies in the first half of the 1960s. It was equipped with four General Electric T64-GE-1 engines with a capacity of 2850 hp each. with., which rotated fiberglass propellers of the Hamilton Standard brand with a diameter of 4.7 meters. The tiltrotor, after the modification received the designation XC-142 A, was intended to carry up to 3500 kg of cargo or paratrooper units. A total of 5 vehicles were built, the first one was flown on September 29, 1964, and on January 11, 1965, the transition between modes was made for the first time in flight: vertical takeoff, horizontal flight and vertical landing.
The first XC-142A was handed over to the US Air Force in July 1965. During subsequent flight tests, five built prototypes flew 420 hours (488 flights, 39 military and civilian pilots were involved), including takeoffs / landings on the deck of ships, participation in search and rescue exercises, dropping paratroopers and dropping cargo at low altitude. The tiltrotor had a maximum takeoff weight of 20227 kg, an empty weight of 10270 kg, and could take a payload of 3336 kg (32 paratroopers in full gear or 24 stretcher wounded with 4 escorts).
During testing and trial operation, four convertiplanes were broken. The US Department of the Air Force in 1966 tentatively announced its intention to purchase a batch of serial S-142 B convertiplanes, but it did not come to a contract, and the remaining copy (plant No. 65–5924) was transferred to NASA, where it was operated from May 1966 to May 1970 of the year . A civilian version was proposed, the Downtowner, designed to carry 40-50 passengers at a speed of 470 km / h with only two engines running. However, this idea was also not implemented.
Simultaneously with the work on the XC-142 A, another company, Curtis-Wright, carried out work on the X-100 tiltrotor, a distinctive feature of which was the presence of two rotors. The single-seat X-100, as well as a number of other convertiplanes, was a relatively inexpensive experimental vehicle designed to assess the technical feasibility of creating and effectively operating an aircraft with rotary propellers.

X-100 tiltrotor

The X-100 had one Lycoming YT53-L-1 turboprop engine with an 825 horsepower. s., which was located in the fuselage and set in motion both rotary screws, while balancing in hover mode and when flying at low speeds was provided using a controlled jet nozzle located in the tail section of the machine. The main task in the framework of the X-100 program was to develop a tiltrotor scheme with rotary screws, which was necessary for the development and construction of a more important device of this type, first designated M-100, and then X-19. It was also necessary to work out the issues of creating fiberglass propeller blades.
Work on the X-100 began in February 1958, and in October of the same year, intensive blowdowns in the wind tunnel began. On September 12, 1959, he made the first hover, and on April 13, 1960, the first transition from one regime to another was completed. However, in subsequent tests it turned out that the flight characteristics of the tiltrotor are not entirely satisfactory, and the balancing and control system at low flight speeds does not meet the requirements.
On the other hand, the feasibility of the X-100 concept was fully proven, which prompted the developers to move on to work on the heavier X-19 tiltrotor. On July 21, 1960, testing of the X-100 was completed and the vehicle was moved to NASA's Langley Research Center and then donated to the National Air and Space Museum at the Smithsonian Institution.

X-19 tiltrotor

The M-200 tiltrotor (from Model 200) had an "airplane" fuselage and two small-span tandem wings, at the tips of which there were rotary propellers with a diameter of 3.96 meters each, driven by two Lycoming T55-L-5 turboshaft engines with a capacity of 2620 l. With. In case of failure of one engine, the cross transmission provided the drive of all four propellers from the other. The US Department of Defense considered the possibility of using this tiltrotor in the role of reconnaissance and transport. The car was flown on June 26, 1964, after which it was transferred for further testing to the US Air Force. She was given the new designation X-19. However, as in the case of the X-100, the performance obtained was worse than expected. August 25, 1965 X-19 crashed in the next flight.

"Magnificent" Troika "from the company" Bell "

One of the decisive, turning point projects in the history of tiltrotor construction was the XV-3, developed by Bell Aircraft. Her first experience in this area was the Envelope-O-Plain Model 50 tiltrotor developed on her own initiative, followed by a whole series of projects, most of which, however, did not advance further than the drawing board.
However, then her finest hour came - the company became the favorite in the tender announced in 1950 by the US Army and Air Force commands as part of the Convertible Aircraft Program. The following year, the company received a contract to build and conduct extensive testing of two machines of the XV-3 Convertiplane type.

Restored tiltrotor XV-3

The XV-3 was a small tiltrotor with a takeoff weight of 2177 kg, a length of 9.25 meters and a wingspan of 9.55 meters. The crew consisted of two pilots, arranged according to the "tandem" scheme. The power of the engine located in the fuselage was 450 liters. With. The machine had two three-bladed propellers, which were installed in gondolas located at the ends of the wing - on special rotary devices. The translation of the screws from a vertical to a horizontal position was carried out mechanically and took no more than 10 seconds.
Ground tests of the machine started in early 1955 at the company's plant in Hurst, Texas. Then the turn came to flight tests - the first car (Ship 1) took off on August 11, 1955, but during the 18th flight it suffered a minor accident. Fortunately, there were no casualties then. The first time the regime change was performed on July 11, 1956, but already on October 25, during another attempt, an accident occurred - the car crashed, and the pilot was seriously injured.
During the tests, it quickly became clear that the car had a lot of flaws. Partially they were eliminated on the second copy (Ship 2). On December 18, 1958, it successfully transitioned from one flight mode to another, after which the car was handed over for testing by the Air Force and NASA, during which 11 pilots flew the XV-3 for a total of 125 hours in 250 flights, performing 110 "full transitions". In addition, various takeoff and landing options were worked out. So, for example, when taking off with a short takeoff run, the car at a speed of about 57 km / h rose into the air with a run of only 61 meters (the propellers were installed at an angle of 80 degrees to the horizon). The test pilots managed to reach an altitude of 3750 m on the XV-3 and develop a speed of 213 km / h, as well as work out the landing in autorotation mode.
Ultimately, the construction and testing of two XV-3s was an important milestone in the global aircraft industry. However, the success was only partial: the very possibility of building a tiltrotor was proved, but, in fact, it could not represent practical value.

Convertiplane XV-3 during a test flight

The further fate of the tiltrotor is very interesting. At the end of 1966, the remaining XV-3, head. No. 54–148, was moved to an aircraft storage facility at Davis-Monthan Air Force Base in Tucson, Arizona, and was forgotten for almost two decades. It wasn't until 1984 that specialists from the XV-15 tiltrotor design team, developed by Bell, tracked it down at the US Army Aviation Museum at Fort Rucker, Alabama. The device was restored in December 1986, after which it was dismantled and mothballed in a covered hangar, where it remained for another two decades. Finally, on January 22, 2004, the XV-3 was moved to Bell's Plant 6 in Arlington, Texas, and the factory's specialists began to restore it under the guidance of former XV-3 program engineer Charles Davis. Two years later, the XV-3 took its place on display at the National Museum of the US Air Force in Dayton, Ohio, where it remains to this day.

Convertiplanes in the USSR

Mi-30 tiltrotor in level flight

Soviet designers, realistically assessing the large number of difficulties associated with the development of a convertible apparatus, for quite a long time were skeptical of various "doubtful" projects, but nevertheless, work on tiltrotor projects was also in the USSR.
In particular, in KB Mil. Mi-30 is a Soviet project of a multi-purpose tiltrotor, the development of which began in 1972 at the Moscow Helicopters. M. L. Mil, the project leader was M. N. Tishchenko. Inside the design bureau, this design scheme had its own designation "rotorplane". The main task in creating the Mi-30 was to ensure such parameters as range and flight speed, which would surpass the performance of helicopters of a similar class.

The Mi-30 convertoplane was considered by the creators as a promising replacement for the Mi-8 multi-purpose helicopter. In the original project, the Mi-30 was designed to carry 2 tons of cargo and 19 passengers, but later the carrying capacity of the machine was increased to 3-5 tons, and the passenger capacity was increased to 32 people.

In 1972, the designers of the MVZ them. M. L. Mil, on their own initiative, created a project proposal for a transport and passenger tiltrotor, called the Mi-30. According to the terminology available in the USSR, it was originally called a helicopter-aircraft, but later the Milevites came up with their own designation for it - a propeller plane. The main task in the design of the Mi-30 was to ensure flight performance, primarily the range and flight speed. Initially, it was supposed to carry up to 2 tons of cargo and 19 troops.

As a power plant for the new machine, it was planned to use 2 TV3-117 engines located above the cargo compartment, the engines were supposed to drive 2 main-pull propellers with a diameter of 11 m each using a transmission. The screws were located at the ends of the wing consoles. The estimated flight speed of the Mi-30 was estimated at 500-600 km / h, and the flight range was to be 800 km. The take-off weight of the machine is 10.6 tons. The Milevites were able to involve TsAGI in the research within the framework of this program. Soon, by joint efforts, the construction of an aerodynamic stand was started to test the propeller model. At the same time, the designers of the Mil Design Bureau created an experimental flying radio-controlled model of a rotorcraft in order to study the transitional modes, controllability and stability of the device in flight.

During the development process, the customer wanted to increase the carrying capacity of the Mi-30 to 3-5 tons, and increase the passenger capacity to 32 people. As a result, the propeller project was redesigned to use 3 forced TV3-117F engines. At the same time, the diameter of the load-bearing propellers grew to 12.5 m, and the Mi-30 takeoff weight to 15.5 tons. conducted thorough analytical studies of the problems of structural dynamics, aeroelasticity, flight dynamics and aerodynamics characteristic of convertible vehicles.

Considering the depth of project development, the existing factory experience in solving difficult problems, the Commission of the Presidium of the Council of Ministers of the USSR on armaments in August 1981 issued a decree on the creation of a Mi-30 helicopter with a convertible carrier system (rotorplane). The created technical proposal was submitted for consideration by the customer and the MAP institutes. The military approved the creation of the machine, but demanded that more powerful engines be put on the rotorcraft - 2 D-136 engines, the estimated weight of the tiltrotor increased to 30 tons.

As a result, the creation of the Mi-30 was included in the state armament program for 1986-1995. But the collapse of the USSR and the resulting economic difficulties put an end to the Mi-30 propeller plane, and he never got out of the stage of analytical and design research. In the last year of the existence of the USSR, OKB specialists designed 3 different propeller planes: Mi-30S, Mi-30D and Mi-30L, which had a carrying capacity of 3.2, 2.5 and 0.95 tons, respectively, and a passenger capacity of 21, 11 and 7 people. The first 2 convertiplanes had a maximum takeoff weight of 13 tons. It was planned to equip them with power plants from 2 TV7-117 engines, and the third Mi-30L (weighing 3.75 tons) with a power plant from 2 AL-34s. Work was also carried out on the creation of combat options.

In the early 1990s, the possibility of participation of the Moscow Helicopter Plant named after M. L. Mil in European projects and programs, including Eurofar and Evrika, which were aimed at creating convertiplanes similar to the Mi-30. But at that time in Russia there were no conditions for organizing such joint projects.

tiltrotor - This is a twin-rotor aircraft that combines the advantages of a helicopter and an airplane at the same time. On such an apparatus, both propellers are located on the wings of the apparatus. For vertical takeoff or landing, the propellers are parallel to the ground. After lifting to the required height, the screws turn through an angle of approximately 90 degrees and become pulling screws.

The evolution of these devices began with autogyros. The first gyroplane was the British Fairey Rotodyne (1950), manufactured by the Fairy company (here is such a play on words - the gyroplane was created by the Fairey company). It is mistakenly called a rotorcraft. However, the world's first classic rotorcraft, we can safely consider the development Kamov- KA-22 (1960). By the way, according to Wikipedia, only one sample survived KA-22 And if someone knows where he is now, please share the information. Already in the early 60s, KA-22 removed from mass production after a series of disasters. Further in the USSR, they did not even intend to return to devices of this class.

However, US leaders had a different opinion and continued to develop the direction of rotorcraft, allowing the screws to change the thrust angle, thereby creating a new type of aircraft - tiltrotor. In 1989, the first tiltrotor was tested, on which the best US developers worked 30 years. So the Bell V-22 Osprey saw the light. But he was not appreciated. Already in the early 90s, it was decided to give this toy to the Marines. At V-22(as with all tiltrotor developments) I see one drawback - the loss of traction due to the resistance of the wings, which are under the propellers. A short discussion of helicopter pilots in the forum suggests that V-22 really good.

I think that it is with the advent of information about V-22, as a new type of aircraft, we also took up the development of an analogue. Already in 1972, the specialists of the Moscow Helicopters named after. M.L.Milya, began the development of a tiltrotor Mi-30. The first flight of this device was supposed in 1991. More about development Mi-30 read . But due to the difficult economic situation in the country, Mi-30 and remained on paper.

Here I also want to note that the world's fastest helicopter for 2008 (performed by the way rather like autogyro) does not reach and 500 km/h. A V-22 already since 1990 reaches its maximum speed 638 km/h. In addition, it accommodates 24 paratroopers.

The fact that VA-22, which turned out with excellent technical characteristics, was rejected without argument to the Marine Corps, and even in a "reduced edition", as well as a not very clear incompleteness of development Mi-30, tells me that most likely this type of apparatus (tiltiplanes) is still being developed, but not advertised.

AND NOW THE MOST IMPORTANT! In the movie "Avatar", in my opinion, demonstrated almost perfect aircraft, made on the principle of a tiltrotor. In all reviews of the film, it is so, correctly called - a tiltrotor.

The screws of this machine can rotate in almost any direction, not even in sync which allows him to be super-maneuverable. It has the ability to develop huge speeds or stand still in the air, even in strong winds, compensating for wind correction with the help of an optimal angle of rotation of the propellers. The presence of safety rings allows you to protect the screws from breakage during maneuvers in extreme conditions. This ideal general purpose aircraft. It is not necessary to talk about the military sphere here.

Such aircraft would become indispensable assistants in the service of the police, ambulance, and rescue services. I also foresee the emergence of a new sport - convertoplanning. Convertiplane races would gather crowds of spectators around the world, where the main competitive moment was used not only the speed of this device, but also its super-maneuverability.

Of course, in the future, to improve performance, convertiplanes will use rocket launchers instead of propellers. A propeller is just an example of a source of thrust for a tiltrotor. The photo next to it is just an example of a jet tiltrotor.

I am not a mega-specialist in the aviation technical environment and was guided in this article mainly by logic, so I will be glad if my assumptions about the future of convertiplanes are corrected by a competent specialist.

On the video, the trailer for the game "Avatar". Watch only the first minutes of the video, which demonstrates the player's flight on a tiltrotor. Just pay attention to how maneuverable this thing would be in reality.

The Hummingbird tiltrotor, unlike other convertiplanes, has an innovative reactive rotor drive in combination with the author's blade swashplate, which made it possible to avoid design errors made in existing tiltrotor models, the high cost and exceptional complexity of which do not allow them to be mass-produced.

The technology is awaiting funding!

Description:

The Hummingbird tiltrotor, unlike other convertiplanes, has a reactive rotor drive. At the same time, in the development of the tiltrotor, domestic serial components and assemblies, time-tested, are used. The fuselage is made of composite materials. Bearing frame - from aviation stamps become.

The design uses an innovative reactive rotor drive in combination with the author's blade swashplate, which made it possible to avoid design errors made in already existing tiltrotor models, such as the Bell V-22 "Osprey" - the high cost and exceptional complexity of which do not allow it to be mass-produced.

Difficulties in the design of the tiltrotor Bell V-22 "Osprey":
– transmission and power plant. The traditional power plant, shafts synchronizing the rotation of the rotors, gearboxes, angular gears significantly increase the weight and complexity of the design. All this negatively affects the payload of the aircraft,
– hydraulic control. Dubbed three times
– electrical control system and provision of on-board equipment with electricity Duplicated three times.

Sophisticated hydraulics, electrical and electronics make this aircraft - the Bell V-22 Osprey tiltrotor - unusually expensive and difficult to fly and operate on a daily basis.

At the tiltrotor Hummingbird with a jet drive rotors there is no traditional power plant, transmission and various gearboxes as on the Bell V-22 "Osprey" or AW-609.

The tiltrotor Hummingbird flies, converts and is controlled in flight due to a jet propulsion and a change in the thrust vector of the rotors, by means of a swashplate, which changes the overall and cyclic pitch of the blades.

The rotor or screw of the Hummingbird tiltrotor rotates due to the jet engine at the end of the blade.

The tiltrotor Hummingbird has no analogues in the world and runs on liquefied hydrocarbon gas (propane-butane), and not on standard aviation fuel, which significantly reduces the cost of operation. For example, RT (GOST 10227-86) costs from 50 rubles per liter, and a liter of liquefied hydrocarbon gas- 14 rubles. Economic indicators during the operation of the Hummingbird tiltrotor are 7 times cheaper than a helicopter. Fuel consumption within 5 liters of gas per 100 km. flight. Standard equipment allows you to have a flight range of up to 3500 km. At the request of the customer, the flight range can be increased by several thousand kilometers.

The service life of this tiltrotor is equal to the service life of all components and assemblies, which is 20 years. The only "consumable" in this design is the bearings used in the carrier system, rated for 40,000 hours. Replacement of such a bearing can be carried out by one qualified person within 5 hours.

The Hummingbird tiltrotor is produced in 2 modifications: 4-seater and 8-seater modifications.

Advantages:

- simplicity of design,

– reliability of technical equipment. We use domestic serial components and assemblies, time-tested,

- safety. The simplicity of the design and the use of time-tested serial components and assemblies makes the Hummingbird one of the most reliable aircraft. The tiltrotor is equipped with four automated options for protection during an emergency landing. The first three options give the pilot the opportunity to land the device on their own in one mode or another, or the protection system automatically releases a special emergency parachute on its own,

- the service life of the Hummingbird tiltrotor is 20 years,

– economy. Works on liquefied hydrocarbon gas - propane-butane. 7 times more economical than a conventional helicopter,

- easy to manage,

– high flight speed up to 800 km/h,

– high rate of climb up to 90 m/s in dynamics,

– takes off and lands from any unprepared site measuring 3x5 meters, on swampy and overgrown with shrubs up to 2.5 meters high, on the water surface with waves up to 3 points,

– the possibility of operation in the conditions of the Far North without additional means and anti-icing systems,

– low price compared to similar aircraft. One of the best-selling helicopters in its class, the Robinson R-44 costs from 30,000,000 rubles. The minimum price for a 4-seater version of the Hummingbird tiltrotor is 15,000,000 rubles, for an 8-seater version - 20,000,000 rubles,

– comfort. Low vibration load and low noise level by aviation standards make it quite comfortable to fly at any distance.

Specifications:

Characteristics:	Meaning:
Length, m	6,5
Width, m	5,5
Height, m	3,25
span, m	10,6
Crew / passengers, pers.	1 + 3 (1 + 7)
Empty weight, kg	no more than 200
550 (up to 900)
Full takeoff weight, kg	800 (up to 1200)
Maximum speed, km/h	up to 800
Cruise speed, km/h	570
Rate of climb, m/s	30
Flight range, km	3500
Flight duration, hour	6,5
Working height, m	up to 7 000
Maximum height, m	8 000
Maximum power of the power plant, h.p.	174
Fuel	propane/butane mix
Fuel consumption, l/h	30
Fuel consumption per 100 km, l	5
Overhaul interval, hours	40 000

Note: description of the technology on the example of the Hummingbird tiltrotor.

tiltrotor

The very first detailed tiltrotor project was the Wesserflug P.1003, developed in Germany in 1938 by designers Rohrbach and Simon. According to the project, it was supposed to create a two-wing tiltrotor with a rotary wing (more precisely, only the ends of the wing should have rotated, with a fixed middle). However, due to the war that began the following year, the project was never implemented. The second detailed tiltrotor project in the same Germany was not implemented due to the end of the war. Since firms Focke and Ahgelis, intended to build their Fa-269 as wunderwaffe. According to this project, the tiltrotor was supposed to have “pushing (rather than pulling, as in classic tiltrotor projects) three-bladed propellers, which, thanks to a very high landing gear, could turn down during takeoff. Curiously, only one (but very powerful) engine was supposed to be located in the fuselage, and inside each wing there should have been a transmission leading to a rotary screw.

Other unrealized projects wunderwaffe with helicopter takeoff Heinkel - Wespe and Lerche had neither rotary propellers nor rotary wings, but had to take off and land like a helicopter due to the vertical position of the fuselage during takeoff. Both projects differed only in weight and dimensions, and had a similar design from a hull cut in half in the middle of which there should have been a pair of screws enclosed inside one annular wing. With a vertical fuselage, it was supposed to take off and land, also an extremely original unrealized project wunderwaffe- Tribfluegel from Focke-Wulf, which has a rotating Y-shaped wing, which is also a three-bladed propeller, rotating not from a piston, but ... a jet engine, like a Bengal wheel. Curiously, Heinkel had a similar project wunderwaffe- Ypsilon, which differed from the Focke-Wulf Tribfluegel only in that its wing did not rotate (that is, unlike the Focke-Wulf, it should not have been a rotorcraft, in the literal sense of the word, but simply a vertical take-off jet).

Tiltrotor with turning screws

Tiltrotor with rotary screws (tiltrotor, (tiltrotor) - aircraft, which combines vertical takeoff / landing according to the helicopter principle with movement at the speed of a turboprop aircraft.

Usually, it is not the screws themselves that are turning, but nacelles with screws and engines (as in Bell V-22 Osprey), but there are also designs in which only the propellers turn, and the engines (for example, located in the fuselage) remain stationary. An example of a rotorcraft where only the propellers turn is Bell XV-3.

It should be noted that the term tiltrotor is not equivalent to a tiltrotor, since it is a specific implementation scheme for a tiltrotor.

tilt-wing tiltrotor

Tiltwing X-18 turns wing

Four-engine experimental tiltwing XC-142A

There is a variant of a tiltrotor called a tiltrotor with a rotary wing (tiltwing; Tiltwing, from tilt - turn and wing - wing), when the entire wing rotates, and not just the tips, like a tiltrotor.

The disadvantage of the rotary wing is its great complexity, the advantage is that during vertical takeoff the wings do not obscure the airflow from the propellers (thus increasing the efficiency of the propellers).

Tiltrotor with propellers in annular channels

Aircraft with vertical takeoff (or short take-off and landing) with propellers in the annular channels can be referred to as having rotary propellers or having a rotary wing.

Their peculiarity is that the screws are located inside a special ring, which is sometimes called the "annular" wing, in aircraft modeling, such a screw in the annular channel is often called the term "fan" propulsion(in aircraft modeling, such a propeller is usually hidden inside a mock-up jet engine). This type of propeller has a very high speed of the air flow thrown off by the propeller, which makes it possible to get by with very small wings, providing a high compactness of the tiltrotor. The same advantage turns into a serious drawback when performing the functions of a helicopter, as a result of which funding for the development of such convertiplanes was stopped as soon as it came to their ability to completely replace the helicopter.

Examples of such convertiplanes are Bell X-22 A, Douk VZ-4DA and Nord 500.

VTOL with vertical position

Vertical takeoff and landing aircraft with a vertical body position (tailsitter, tailsitter () , from tail - tail and sitter - sitting) - layout option VTOL. Such an aircraft takes off and lands on its own tail like a helicopter takes off and lands, and then goes into horizontal "aircraft" flight. Despite the impossibility of landing “on an airplane”, it is not a tiltrotor, since when switching to a horizontal flight mode, the propellers do not turn relative to the wing and fuselage of the aircraft. The complexity of the scheme lies in the organization of control in the modes of vertical and horizontal flights, as well as transitional ones - it is difficult for the pilot to navigate, because the same controls perform different functions in different modes, in addition, visibility is difficult in vertical modes. Nevertheless, the absence of large turning parts, as well as a single power plant for vertical and horizontal flight modes, made it possible to simplify the design of the device, and this scheme was popular with designers for a long time. This scheme was used by both jet and screw VTOL aircraft. A few VTOL aircraft built according to this scheme remained experimental prototypes.

In 1972, at the Mil Design Bureau, a propeller project arose Mi-30, having a classic scheme with a pair of rotary screws (gondolas with screws and engines). Within the framework of this project, analytical and design studies were carried out, which consisted of both theoretical work and tests of models of the rotary screw on an aerodynamic stand. Based on the results of these works, relevant studies were introduced into the rotorcraft project, for example, the take-off weight increased from 10.6 to 30 tons, with a simultaneous increase in both engine power and payload. The construction of the first flying models was scheduled for 1986-1995, however, due to the upcoming perestroika, the rotorcraft was not built.