Yakovlev Yak-15
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The Yakovlev Yak-15 (;
NATO reporting name NATO uses a system of code names, called reporting names, to denote military aircraft and other equipment used by post-Soviet states, former Warsaw Pact countries, China, and other countries. The system assists military communications by providi ...
: Feather,
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/ DOD designation Type 2) is a first-generation
Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
turbojet fighter developed by the
Yakovlev The Joint-stock company, JSC A.S. Yakovlev Design Bureau () is a Russian aircraft designer and manufacturer (design office prefix Yak). Its head office is in Aeroport District, Northern Administrative Okrug, Moscow. It is a subsidiary of Yakovle ...
design bureau (OKB) immediately after
World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
. The main fuselage was that of
Yakovlev Yak-3 The Yakovlev Yak-3 (Russian language, Russian: Яковлев Як-3) is a single-engine, single-seat World War II Soviet Union, Soviet fighter aircraft, fighter. Robust and easy to maintain, it was much liked by both pilots and ground crew.Glan ...
piston-engine fighter modified to mount a
reverse-engineered Reverse engineering (also known as backwards engineering or back engineering) is a process or method through which one attempts to understand through deductive reasoning how a previously made device, process, system, or piece of software accompl ...
German
Junkers Jumo 004 The Junkers Jumo 004 was the world's first production turbojet engine in operational use, and the first successful axial compressor turbojet engine. Some 8,000 units were manufactured by Junkers in Germany late in World War II, powering the Mess ...
engine. The Yak-15 and the Swedish Saab 21R were the only two jets to be successfully converted from piston-power to enter production.Gunston 1995, p. 472 280 aircraft were built in 1947. Although nominally a fighter, it was mainly used to qualify piston-engine-experienced pilots to fly jets.


Design


Development and description

On 9 April 1945, the
Council of People's Commissars The Council of People's Commissars (CPC) (), commonly known as the ''Sovnarkom'' (), were the highest executive (government), executive authorities of the Russian Soviet Federative Socialist Republic (RSFSR), the Soviet Union (USSR), and the Sovi ...
ordered the Yakovlev OKB to develop a single-seat jet fighter to be equipped with a single German Jumo 004 engine. To save time, Yakovlev based the new design (known as the Yak-3-Jumo or Yak-Jumo) on the latest version of his successful
Yakovlev Yak-3 The Yakovlev Yak-3 (Russian language, Russian: Яковлев Як-3) is a single-engine, single-seat World War II Soviet Union, Soviet fighter aircraft, fighter. Robust and easy to maintain, it was much liked by both pilots and ground crew.Glan ...
piston-engined fighter. The piston engine was removed and the jet engine was mounted underneath the forward
fuselage The fuselage (; from the French language, French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds Aircrew, crew, passengers, or cargo. In single-engine aircraft, it will usually contain an Aircraft engine, engine as wel ...
so that its exhaust exited underneath the middle of the fuselage. To protect the fuselage, a steel heatshield was added to its bottom. The deeper forward part of the fuselage caused the configuration of the aircraft to resemble a "pod-and-boom". Very few changes were made to the metal fuselage other than at the aircraft's nose. This was recontoured to accommodate the armament of two Nudelman-Suranov NS-23
autocannon An autocannon, automatic cannon or machine cannon is a automatic firearm, fully automatic gun that is capable of rapid-firing large-caliber ( or more) armour-piercing, explosive or incendiary ammunition, incendiary shell (projectile), shells, ...
, an additional fuel tank above the engine and the engine itself. No changes were made to the wings other than the elimination of the air intakes for the oil cooler and the bending of the front wing spar into an inverted U-shape to clear the engine. The
vertical stabilizer A vertical stabilizer or tail fin is the static part of the vertical tail of an aircraft. The term is commonly applied to the assembly of both this fixed surface and one or more movable rudders hinged to it. Their role is to provide control, sta ...
was slightly enlarged, but the
tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters ...
was unmodified. The
conventional landing gear Conventional landing gear, or tailwheel-type landing gear, is an aircraft Landing gear, undercarriage consisting of two main wheels forward of the Center of gravity of an aircraft, center of gravity and a small wheel or skid to support the tail ...
was also unmodified other than the tailwheel which now used several steel
leaf spring A leaf spring is a simple form of spring (device), spring commonly used for suspension (vehicle), suspension in wheeled vehicles. Originally called a ''laminated'' or ''carriage spring'', and sometimes referred to as a semi-elliptical spring, e ...
s as shock absorbers. The Yak-Jumo carried a total of of fuel. Yak-15 forward fuselage and engine
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tests began in October 1945, but the heatshield proved to be too short and the heat from the engine exhaust melted the
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skin of the rear fuselage as well as the rubber
tire A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineeri ...
of the tailwheel. Modifications to rectify the problems took until late December. By this time a second prototype had been completed with a solid steel tailwheel and an enlarged tailplane. After a few taxiing tests, it was transferred to the Central Aerohydrodynamic Institute (
TsAGI The Central Aerohydrodynamic Institute (also (Zhukovsky) Central Institute of Aerodynamics, , TsAGI) is a Russian national research centre for aviation. It was founded in Moscow by Russian aviation pioneer Nikolai Yegorovich Zhukovsky on Decemb ...
) for full-scale
windtunnel A wind tunnel is "an apparatus for producing a controlled stream of air for conducting aerodynamic experiments". The experiment is conducted in the test section of the wind tunnel and a complete tunnel configuration includes air ducting to and f ...
testing that lasted until February 1946. On the 26th of that month, the Council of People's Commissars issued requirements that the aircraft should have a maximum speed of at
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and a speed of at an altitude of . It should be able to climb to that altitude in minutes or less and it should have a range of at 90% of maximum speed. Two prototypes were to be ready for flight testing on 1 September.Gordon 2002, p. 50 The Mikoyan-Gurevich OKB was developing the
MiG-9 The Mikoyan-Gurevich MiG-9 (, USAF/DoD reporting names, USAF/DoD designation: Type 1, NATO reporting name: Fargo) was the first turbojet fighter aircraft, fighter developed by Mikoyan, Mikoyan-Gurevich in the years immediately after World War I ...
at the same time. According to aviation historians
Bill Gunston Bill Gunston (1 March 1927 – 1 June 2013) was a British aviation and military author. He flew with Britain's Royal Air Force from 1945 to 1948, and after pilot training became a flying instructor. He spent most of his adult life doing researc ...
and Yefim Gordon, representatives from Yakovlev and Mikoyan-Gurevich tossed a coin on 24 April 1946 to determine which aircraft would be the first Soviet jet to fly. Yakovlev lost and the Yak-Jumo made one circuit of the airfield before landing. The manufacturer's flight testing of the aircraft was completed on 22 June, but its early success caused the
Council of Ministers Council of Ministers is a traditional name given to the supreme Executive (government), executive organ in some governments. It is usually equivalent to the term Cabinet (government), cabinet. The term Council of State is a similar name that also m ...
to issue a new requirement on 29 April for two aircraft powered by the Soviet-built RD-10 engine (known as the Yak-15, Yak-15RD10 or Yak-RD). Aside from the new engine, the requirement differed from the previous one only in a range of at optimum cruise speed and a reduction of the maximum
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to . Two prototypes were ordered to be available for flight testing on 1 September 1946. Yakovlev was able to adapt the two existing prototypes to the RD-10 with little trouble and one aircraft participated in the August 1946 Tushino
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. The day after the aerial display,
Joseph Stalin Joseph Vissarionovich Stalin (born Dzhugashvili; 5 March 1953) was a Soviet politician and revolutionary who led the Soviet Union from 1924 until Death and state funeral of Joseph Stalin, his death in 1953. He held power as General Secret ...
summoned Artem Mikoyan and Aleksandr Yakovlev to his office and ordered that each OKB build 15 aircraft to participate in the 7 November parade in
Red Square Red Square ( rus, Красная площадь, Krasnaya ploshchad', p=ˈkrasnəjə ˈploɕːɪtʲ) is one of the oldest and largest town square, squares in Moscow, Russia. It is located in Moscow's historic centre, along the eastern walls of ...
commemorating the anniversary of the
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. Factory No. 31 in
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was chosen to build the new aircraft because it was still building conventional Yak-3s and could easily switch to the jet fighter. All 15 aircraft were built before the deadline, although they lacked any armour, were provided with an enlarged fuel tank in lieu of armament, and had an incomplete
avionics Avionics (a portmanteau of ''aviation'' and ''electronics'') are the Electronics, electronic systems used on aircraft. Avionic systems include communications, Air navigation, navigation, the display and management of multiple systems, and the ...
outfit. The parade was canceled and two of the aircraft were modified with a single 23 mm cannon and began State acceptance trials which lasted until April 1947. The tests revealed a number of problems in that the thick wing inherited from the Yak-3 limited the top speed of the aircraft, the engine exhaust damaged the surface of the airfield, the cockpit often filled with smoke from kerosene and oil that had dripped onto the engine, and the aircraft was very short-ranged. Despite these problems, the Yak-15 proved to be very easy to fly, even for pilots accustomed to piston-engined fighters, and caused the VVS to accept the fighter as a conversion trainer. Even before the State acceptance trials were completed, the Council of Ministers ordered the aircraft into production in December 1946. 50 aircraft were to be built between January and April 1947, equally split between single-seat aircraft and two-seat trainers, armed with only a single cannon. The trainer ran into serious development difficulties and all the aircraft of the first batch were single-seaters. Fifty of these participated in the
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flypast in Moscow in 1947. A total of 280 Yak-15s were produced through the end of the year, exclusive of prototypes. The aircraft were distributed in small numbers to fighter aviation regiments based in the USSR, Poland, Romania, Hungary, and Manchuria for use as conversion trainers. The aircraft's manoeuvrability led it to be used by a number of informal acrobatic display teams throughout the late 1940s. A single prototype of the two-seat trainer was the first aircraft of the first production batch built by Factory No. 31 in the fall of 1946. The prototype did not begin manufacturer's flight testing until 5 April 1947, even though the primary differences from the single-seat version were limited to a redesigned forward fuselage that accommodated an additional cockpit for the trainee where the armament used to be and a sideways-opening,
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. The trainer was initially designated as the Yak-Jumo ''vyvoznoy'', but it was eventually designated as the Yak-21 although some documents refer to it as the Yak-15V, Yak-15UT or Yak-21V. Further work on the trainer was cancelled with the success of the trainer version of the Yak-17 with its
tricycle undercarriage Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', that is arranged in a tricycle fashion. The tricycle arrangement has one or more nose wheels in a single front undercarriage and two or more main wheels slightly aft of th ...
. One Yak-15 was used to test a prototype aerial refueling system in 1949, although the installation on the fighter and the
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bomber used as the tanker were both dummies to test procedures and fit.


Yak-17-RD10

On 29 April 1946, five days after the Mikoyan-Gurevich I-300 (MiG-9 Prototype) and the Yak-Jumo made their first flights, the Council of Ministers ordered that the Yakovlev OKB begin design of a new aircraft similar to the Yak-Jumo, using the RD-10 engine with improved aerodynamics. This generally resembled the original aircraft, but the wings were entirely redesigned with laminar flow airfoils, the tail structure was enlarged and an
ejection seat In aircraft, an ejection seat or ejector seat is a system designed to rescue the aircraft pilot, pilot or other aircrew, crew of an aircraft (usually military) in an emergency. In most designs, the seat is propelled out of the aircraft by an exp ...
was fitted. The back of the seat was armoured and the pilot was also protected by a bulletproof
windscreen The windshield (American English and Canadian English) or windscreen (Commonwealth English) of an aircraft, car, bus, motorbike, truck, train, boat or streetcar is the front window, which provides visibility while protecting occupants from t ...
. The entire canopy was also redesigned to accommodate the new windscreen. The landing gear could not be housed in the thin wings so it was redesigned to retract into the fuselage. Low and high wing loading wing versions were considered, but the low wing loading wings were chosen for the prototype. At an altitude of 5000 meters, the Yak-17-RD10, as the new fighter was designated, was expected to have a top speed of ; a significant improvement over that of the production Yak-15. The aircraft was completed on 3 September and ground tests lasted until 26 September, but it never flew as the Yak-15 had already been ordered into production and its
conventional landing gear Conventional landing gear, or tailwheel-type landing gear, is an aircraft Landing gear, undercarriage consisting of two main wheels forward of the Center of gravity of an aircraft, center of gravity and a small wheel or skid to support the tail ...
was already deemed obsolete.Gordon 2002, p. 62


Survivors

Only one Yak-15 survives, 'Yellow 37' at the Vadim Zadorozhny Technical Museum outside
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. It was purchased by the technical museum when the Yakovlev OKB's museum was liquidated in 2006.


Variants

''Data from: ''OKB Yakovlev * Yak-Jumo (Yak-3-Jumo): The first prototypes of the Yak-15 series, powered by captured Jumo 004 engines. * Yak-15-RD10: (also referred to as Yak-RD) Initial designation of prototypes and early production aircraft powered by Soviet-built RD-10 engines (copies of the Jumo 004), with no or reduced armament. * Yak-15: Production aircraft with full armament * Yak-21: Two-seat training version of Yak-15. One built, but not proceeded with because of the success of the trainer version of the Yak-17.Gordon 2002, p. 64 * Yak-15V: (V - ''Vyvozny'' - familiarisation trainer) Alternative designation for the Yak-21. * Yak-15U: (U - ''Uchebnotrenirovochnyy'' - training) Alternative designation for the Yak-21. * Yak-15U (Yakovlev Yak-15U-RD10): (U - ''uloochshenny'' - improved) Improved Yak-15 with tricycle undercarriage and drop tanks, became the prototype of the Yak-17 proper.


Similar but unrelated aircraft

Yak-17-RD10: An experimental aircraft, similar in appearance to the Yak-Jumo aircraft, but actually largely new, incorporating improved aerodynamics, an ejection seat and protection for the pilot. The sole prototype remained unflown after further development was cancelled on 26 September 1946, as taxi tests were being carried out.


Users

;. *
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Specifications (Yak-15)


See also


Citations


Bibliography

* Gordon, Yefim. ''Early Soviet Jet Fighters''. Hinkley, UK: Midland, 2002. * Gordon, Yefim and Dmitriy Kommissarov. ''Early Soviet Jet Fighters''. Manchester, UK: Hikoki Publications, 2014. * Gordon, Yefim, Dimtry Kommissarov, and Sergey Komissariov. ''OKB Yakovlev: A History of the Design Bureau and Its Aircraft''. Hinkley, England: Midland, 2005. * Green, William and Gordon Swanborough. ''The Complete Book of Fighters''. New York: Smithmark, 1994. * Greenwood, John T., Robin Higham and Von Hardesty. ''Russian Aviation and Air Power in the Twentieth Century''. Milton Park, UK: Routledge, 1998. * Gunston, Bill. ''The Osprey Encyclopedia of Russian Aircraft 1875-1995''. London: Osprey, 1995. * Gunston, Bill and Yefim Gordon. ''Yakovlev Aircraft Since 1924''. London: Putnam Aeronautical Books, 1997. * Mikolajczuk, Marian. ''Yakovlev Yak-23: The First Yakovlev Jet Fighters''. Sandomirez, Poland: Stratus, 2008.


External links


Description page on aviation.ru
{{Use dmy dates, date=January 2021 Yak-015 1940s Soviet fighter aircraft Single-engined jet aircraft Low-wing aircraft Aircraft first flown in 1946 Aircraft with retractable conventional landing gear