Convertoroplane

In the prewar years in the USSR, at the Air Force Engineering Academy and the Moscow Aviation Institute, under the leadership of Boris Yuryev (author of a helicopter swashplate ), many conceptual projects of “helicopter-airplanes” were put forward, including both projects of various convertiplanes and projects of various flying saucers (which curiously, Yuryev put forward his first project of a flying saucer back in 1921). However, among all these “helicopter-airplane” projects, the most popular at that time were aircraft projects with a vertical take-off position (that is, before take-off, the plane was rotated 90 ° vertically, then, taking off in a helicopter, turns 90 degrees and flies in an airplane). As for the convertiplanes, as an example of Yuriev’s projects we can cite the concept of a tandem biplane , between which there should have been a pair of rotary screws. There was also a draft rotorcraft in the literal sense of the word, which was supposed to have rotors located inside the wing (similarly, rotors were located on the Ryan - General Electric XV-5 jet). The closest to the classic convertiplanes was the 1934 project - the Sokol fighter with a rotary wing and a pair of propellers in gondolas, in other words having a classic look both for tilings and for fighters of that era (with the exception of gondolas at the ends of the wing and the absence of a propeller on nose that looks like La-5 ). What is curious, despite the classic appearance, the gondolas did not carry engines under the project, and the engine (despite the appearance of the fighter of that era) should have been located behind the pilot's back. None of the projects of "helicopter-airplanes" Yuryev was never implemented, and in the best case, the projects reached only blowing models in the wind tunnel ^[1] . In the postwar years, Yuriev and his students continued to work on creating concepts, but, like in the prewar years, not a single project was implemented. ^[one]

The very first detailed project of a convertiplane was P.1003 of the Wesserflug company, developed in Germany in 1938 by designers Rohrbach and Simon. According to the project, it was planned to create a double-wing tiltrotor with a rotary wing (more precisely, only the ends of the wing should be rotated with a fixed middle). However, in connection with the war that began next year, the project was never implemented ^[1] . The second detailed draft convertiplane project in the same Germany was not implemented already because of the end of the war. Since the company Fokke and Ahgelis intended to build their Fa-269 as a prodigy . According to this project, the tiltrotor was supposed to have “pushing (and not pulling, as in the classic tiltrotor projects) three-bladed propellers, which, thanks to the very high landing gear, could turn down during takeoff. Curiously, it was assumed that there was only one (but very powerful) engine, which was supposed to be located in the fuselage, and a transmission leading to the rotary propeller was supposed to pass inside each wing. ” ^[one]

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

Convertiplanes include the famous English convertible Rotodine helicopter, capable of using the two pulling turboprop engines to enter the rotor autorotation mode, which takes off as a helicopter during take-off. In 1958, this unit was presented at the Farnborough Air Show . He developed a record speed for rotorcraft at a speed of 400 km / h.

A tiltrotor with rotary propellers - a tiltrotor - an aircraft that combines vertical takeoff and landing according to a helicopter principle with movement at a turboprop speed.

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

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

There is a version of a tiltrotor called a tiltrotor with a rotary wing - tiltwing (from tilt - “tilt”, and wing - “wing”), when the entire wing rotates, and not just the wingtips, like a tiltrotor.

The disadvantage of a rotary wing is its great complexity, but the advantage is that with vertical take-off the wings do not obscure the air flow from the screws (thereby increasing the efficiency of the screws).

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

Their peculiarity is that the screws are located inside a special ring, which is sometimes called the “ring” wing , in aircraft modeling such a screw in the annular channel is often called the term “ fan propulsion ” (in aircraft modeling, such a screw is usually hidden inside a model of a jet engine). This type of propulsion device has a very high speed of the air flow discarded by the screw, which makes it possible to dispense with very small wings, providing a high compactness of the tiltrotor. The same advantage turns into a serious drawback in the performance of the functions of a helicopter, as a result of which the funding for the development of such tiltrotopes ceased as soon as it came to their ability to completely replace the helicopter.

Examples of such convertiplanes are the Bell X-22 A, Doak VZ-4 and Nord 500 . ^[2]

A vertical take-off and landing airplane with a vertical hull position - the tailsitter (from tail - “tail” and sitter - “sitting”) - is a variant of the VTOL layout. Such an aircraft takes off and lands on its tail like taking off and landing a helicopter, and then goes into a horizontal “airplane” flight. Despite the impossibility of landing “on an airplane,” it is not a tiltrotor, since when you switch to horizontal flight mode, the screws do not rotate relative to the wing and fuselage of the aircraft. The complexity of the scheme lies in the organization of control in vertical and horizontal flight modes, as well as transitional ones - it is difficult for a pilot to navigate, because the same controls perform different functions in different modes, in addition, viewing is difficult in vertical modes. Nevertheless, the absence of large rotary parts, as well as a single power plant for vertical and horizontal flight modes made it possible to simplify the design of the apparatus, and this scheme has long been popular with designers. This scheme was used both reactive and screw VTOL. The few VTOL aircraft built according to this scheme remained experimental prototypes.

A VTOL with a folding retractable rotor was developed in the USA in the 1950s. For take-off and landing, as well as if it is necessary to fly in hovering mode or at low revs, the main rotor was unfolded and set in motion, and during marching flight in cruising mode, it folded back as the aircraft gained the required speed ^[3] . A rotor with a jet drive, two miniature ramjets at both ends of the rotor blades, operating independently of the main propulsion system of the aircraft, which drives two pulling propellers, like ordinary piston aircraft of that time. The development of the aircraft was carried out by Hiller Helicopters in Palo Alto , California , by order of the US Air Force Research Department, ^{[4] [5]} - this was consistent with the company’s policy to diversify its fields of activity, in addition to Hiller helicopters, since 1955, it began to design gyroplanes, coleopters and other rotorcraft. Bench tests and tests of the dimensional model in an aerodynamic tunnel were carried out at the Aviation Research Center at Wright-Patterson Air Base ^{[6] [7]} . Tests of a new type of rotor and ramjet ramjet drive were carried out directly at the Hiller factory ^[3] . Before the production of an experimental prototype of the VTOL aircraft and flight tests, the matter did not reach.

In 1972, in the design bureau. Mile , the Mi-30 propeller - plan project arose, which had a classic design with a pair of rotary propellers (nacelles with screws and engines). In the framework of this project, analytical and design studies were carried out, consisting of both theoretical work and testing models of the rotor propeller on an aerodynamic bench. Based on the results of these works, changes were made to the propeller plan project, for example, take-off mass increased from 10.6 to 30 tons, with a simultaneous increase in engine power and payload. The construction of the first flying samples was planned for 1986-1995, however, due to the problems of the Perestroika, the Mi-30 was not built ^[2] . There is also information that four samples were released, but during the distillation to the scene of the demonstration, three of them lost control in a storm. It is not known whether this incident was a mistake of pilots or an imperfection of the basic concept, but work on the creation of convertiplanes was discontinued.

One of the first Russian convertiplanes was the project of Aerokso LLC - ERA-100, which has been developed since 2012 and presented at the MAKS-2015 air show. At present, the company Aerokso LLC, based on a patented aerodynamic scheme, is developing and operating a family of ERA-54x convertiplanes with take-off weight of up to 30 kg. She also designed the Aviabike ERA tiltrotor, which became the finalist of the GoFly contest held by Boing. At the MAKS 2017 airshow, a prototype of the experimental unmanned tiltrotor VRT30, developed by the Russian Helicopters holding, is presented. On its basis, it is planned to create a car for the military with a take-off weight of up to two tons. Also, the Kronshtadt group is preparing its own version of a heavy unmanned convertiplane. ^[8]

• Bell V-22 Osprey - the world's only tiltrotor in service
• Curtiss-Wright X-19
• - experimental compact tiltrotor
• Solotrek xfv
• Bell Boeing Quad TiltRotor
• TRIADA Mk. II - the world's only convertible plane UAV with confirmed characteristics (as of 2018)
• Aeroxo ERA series tiltrotoplanes - the first tiltrotor UAVs in Russia

VTOL with jet engines in rotary nacelles

• Bölkow - Heinkel - Messerschmidt EWR VJ 101

• Rotorcraft
• Tiltwing

• Vladimir Spitsyn . What is a tiltrotor? // "City of Vorkuta"
• American engineers are developing a heavy tiltrotor // Membrane , September 23, 2005
• Bell Helicopter TR918 Eagle Eye unmanned reconnaissance tiltrotor tested // Membrane, January 27, 2006
• Comparison of UAV TRIADA Mk. II with classic and hybrid aircraft schemes // Comparison of the parameters of conventional UAVs, a hybrid and a tiltrotor (as of 2018)
• TRH-14 unmanned hybrid tiltrotor from Artamonoff technologies