Alekseyev I-21
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The Alekseyev I-21 was a Soviet
twin-engine A twinjet or twin-engine jet is a jet aircraft powered by two engines. A twinjet is able to fly well enough to land with a single working engine, making it safer than a single-engine aircraft in the event of failure of an engine. Fuel efficien ...
d
jet Jet, Jets, or The Jet(s) may refer to: Aerospace * Jet aircraft, an aircraft propelled by jet engines ** Jet airliner ** Jet engine ** Jet fuel * Jet Airways, an Indian airline * Wind Jet (ICAO: JET), an Italian airline * Journey to Enceladus a ...
fighter, built in the late 1940s. Two
prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...
s were constructed with the designation of I-211, of which one was converted into the I-215 with more powerful engines. A third aircraft was built to evaluate the bicycle landing gear arrangement for use in other aircraft. The fighter was not accepted for production as it was inferior to the
swept-wing A swept wing is a wing that angles either backward or occasionally forward from its root rather than in a straight sideways direction. Swept wings have been flown since the pioneer days of aviation. Wing sweep at high speeds was first investigat ...
fighters like the
Mikoyan-Gurevich MiG-15 The Mikoyan-Gurevich MiG-15 (russian: Микоя́н и Гуре́вич МиГ-15; USAF/DoD designation: Type 14; NATO reporting name: Fagot) is a jet fighter aircraft developed by Mikoyan-Gurevich for the Soviet Union. The MiG-15 was one of ...
.


Development

After working as Lavochkin's right-hand man during
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
, Semyon Alekseyev was appointed as Chief Designer of
OKB OKB is a transliteration of the Russian initials of "" – , meaning 'experiment and design bureau'. During the Soviet era, OKBs were closed institutions working on design and prototyping of advanced technology, usually for military applications. ...
-21 (design bureau) at Gor'kiy. The
Council of the People's Commissars The Councils of People's Commissars (SNK; russian: Совет народных комиссаров (СНК), ''Sovet narodnykh kommissarov''), commonly known as the ''Sovnarkom'' (Совнарком), were the highest executive authorities of ...
directed Alekseyev and other designers to develop jet fighters using more powerful engines than the captured German Jumo 004 and the BMW 003 and their Soviet-built copies. The result of Alekseyev's efforts was the I-21 (Russian: ''istrebitel'' (fighter)), which was planned to be produced in several variants.Gordon & Kommissarov 2014, pp. 405–06 The I-21 was a twin-engined, all-metal, single-seat jet fighter, with straight
laminar flow In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mi ...
wings, mid-set on a circular fuselage. The fighter's Lyul'ka TR-2
turbojet The turbojet is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle. The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and ...
engines were mounted below the wings much like those on the German
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fighter. Underneath the engine
nacelle A nacelle ( ) is a "streamlined body, sized according to what it contains", such as an engine, fuel, or equipment on an aircraft. When attached by a pylon entirely outside the airframe, it is sometimes called a pod, in which case it is attached ...
s were
hardpoint A hardpoint is an attachment location on a structural frame designed to transfer force and carry an external or internal load. The term is usually used to refer to the mounting points (more formally known as a weapon station or station) on the ...
s that could carry bombs or drop tanks. The slightly swept tail unit was cruciform in layout with the tailplane set at approximately half-fin span with slight dihedral. The aircraft's structure was generally constructed from high-strength B-95
duralumin Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of age-hardenable aluminium alloys. The term is a combination of '' Dürener'' and ''aluminium''. Its use as a tra ...
, although high-strength steel and "Elektron"
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alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...
were used for some components. A hydraulically retractable
tricycle undercarriage Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle ge ...
was fitted, using twin wheels for the nose and main landing gear. Hydraulically actuated airbrakes were fitted either side of the rear fuselage. Alekseyev initially planned to arm the aircraft with three Nudelman N-37
autocannon An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bull ...
, each with 30 rounds, but later decided upon a pair of Nudelman-Suranov NS-23 autocannon with 75 rounds per gun. Design work on the I-210 (I-21 version 0) was concurrent with the I-21, probably as a fall back for any lack of availability of the latter's TR-2 engines. The only significant difference was the substitution of BMW 003 engines (or the reverse-engineered RD-20), but the ex-German engine's significantly inferior thrust rating meant that it would never meet the I-21's speed requirement. Even replacing the BMW 003 with the slightly more powerful () Jumo 004 would not allow the I-210 to meet the speed requirement and the project was cancelled before any metal was cut. Construction of the first two airframes, designated as the I-211 (I-21 version 1), began at the end of 1946, under extreme pressure by the Ministry of Aircraft Production to complete initial flight testing by 1 August 1947, to enable the aircraft to take part in the Aviation Day Flypast at
Tushino Tushino ( rus, Тушино, p=ˈtuʂɨnə) is a former village and town to the north of Moscow, which has been part of the city's area since 1960. Between 1939 and 1960, Tushino was classed as a separate town. The Skhodnya River flows across the ...
on 18 August. While one of the two airframes initially produced was used for static testing, the other was fitted with Lyul'ka TR-1 turbojet engines because the intended TR-2 was not available. The engines were mounted in the middle of the wing, with the wing
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continued by banjo rings around the engines, much like those on the British Gloster Meteor fighter. Despite pressure from above, the I-211 was unable to participate in the Tushino display. Flight testing started in late 1947, but only six test flights had been carried out before the I-211 struck a
pothole A pothole is a depression in a road surface, usually asphalt pavement, where traffic has removed broken pieces of the pavement. It is usually the result of water in the underlying soil structure and traffic passing over the affected area. Water ...
on landing, which collapsed the undercarriage. Even the limited amount of flight testing showed it to be faster than the Sukhoi Su-11 which also used the TR-1 engine. Repairs were carried out and the opportunity taken to replace the troublesome engines with imported Rolls-Royce Derwent V engines. Alekseyev took the opportunity to upgrade the aircraft to the I-215 configuration which had been in development since before the first flight of the I-211. The substitution of the
centrifugal-flow Centrifugal compressors, sometimes called impeller compressors or radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery. They achieve pressure rise by adding energy to the continuous flow of fluid through th ...
Derwent for the axial-flow TR-1 forced the redesign and enlargement of the nacelles to accommodate the larger engine. Other modifications included increasing the fuel capacity from to , provision for a ranging
radar Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
in the nose, and better protection for the pilot. The armament was revised to the originally specified N-37 guns, although the ammunition capacity was marginally increased to 35 rounds per gun. Despite good results from flight testing, the I-215 lost out in production orders to the newer generation of swept-winged fighters.Gordon & Kommissarov 2014, pp. 410–11, 414–16, 422 A second I-215 was built to an order from
OKB-1 PAO S. P. Korolev Rocket and Space Corporation Energia (russian: Ракетно-космическая корпорация «Энергия» им. С. П. Королёва, Raketno-kosmicheskaya korporatsiya "Energiya" im. S. P. Korolyov ...
as the I-215D (''dooblyor'', second prototype), to evaluate the bicycle or tandem landing gear configuration. It used wider-diameter paired wheels in a tandem arrangement that retracted into the fuselage, along with small outrigger wheels under the engine nacelles which retracted into fairings. The main undercarriage of the I-215D also incorporated a kneeling feature which could increase the incidence of the aircraft by 3° to assist take-off. Trials with this undercarriage arrangement were successful and paved the way for its use in other Soviet aircraft, including Dr. Brunolf Baade's
Aircraft 150 The OKB-1 150 was a jet bomber designed and produced in the Soviet Union from 1948. Development At the end of World War II, many Germans, German engineers were 'seconded' by the Soviet Union, Soviet government to continue their advanced resear ...
, then under development.


Variants

* I-210 - The initial version with BMW 003 or Tumanskii RD-20 engines, project only.Gordon & Kommissarov 2014, pp. 406–07 * I-211 - The first flyable example completed as the I-211 with Lyul'ka TR-1 engines, rebuilt as the I-215.Gunston 1995, pp. 16–17 * I-211S - I-211 with swept wing and unswept tail, project only. * I-215 - The re-built I-211 with Rolls-Royce Derwent V engines and other minor modifications.Gordon & Kommissarov 2014, pp. 416–18, 422 * I-215D - Bicycle-undercarriage I-215 built to order of OKB-1.Gordon & Kommissarov 2014, p. 422


Specifications (I-211 as tested)


See also


References


Bibliography

* Gordon, Yefim & Kommissarov, Dmitry. ''Early Soviet Jet Fighters''. Manchester, UK: Hikoki Publications, 2014. . * Gunston, Bill. ''The Osprey Encyclopedia of Russian Aircraft 1875–1995''. London: Osprey, 1995. .


Further reading

* Green, William & Swanborough, Gordon. "The Complete Book of Fighters". London: Salamander Books. 1994.


External links


I-215 at Ugolok Neba
site (in Russian) {{Soviet straight-winged jet fighters Alekseyev aircraft Abandoned military aircraft projects of the Soviet Union 1940s Soviet fighter aircraft Twinjets Aircraft first flown in 1947