Yakovlev Yak-15
Encyclopedia
The Yakovlev Yak-15, NATO reporting name
NATO reporting name
NATO reporting names are classified code names for military equipment of the Eastern Bloc...
: Feather, USAF/DOD designation Type 2) was a first-generation
First generation jet fighter
Aircraft classified as first generation jet fighters are the first attempts at creation of military aircraft using jet engines. A few were developed during the closing days of World War II but saw very limited combat operations...
Soviet
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
turbojet fighter
Fighter aircraft
A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets...
developed by the Yakovlev
Yakovlev
The Yak Aircraft Corporation is a Russian aircraft designer and manufacturer...
design bureau (OKB) immediately after World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. It used a reverse-engineered
Reverse engineering
Reverse engineering is the process of discovering the technological principles of a device, object, or system through analysis of its structure, function, and operation...
German Junkers Jumo 004
Junkers Jumo 004
The Jumo 004 was the world's first turbojet engine in production and operational use, and the first successful axial compressor jet engine ever built. Some 8,000 units were manufactured by Junkers in Germany during late World War II and powered the operational Messerschmitt Me 262 jet fighter,...
engine. Along with the Swedish Saab 21R
Saab 21R
|-See also:-References:NotesBibliography* Andersson, Hans G. Saab Aircraft since 1937 . London: Putnam, 1989. ISBN 0-85177-831-3....
, it was one of only two jets to be successfully converted from a piston-powered aircraft and enter production. Although nominally a combat aircraft, it mainly served to convert pilots with experience with piston-engined fighters to jets.
Development and description
On 9 April 1945, the Council of People's Commissars 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) the on the latest version of his successful Yakovlev Yak-3Yakovlev Yak-3
The Yakovlev Yak-3 was a World War II Soviet fighter aircraft.Robust and easy to maintain, it was much liked by pilots and ground crew alike....
piston-engined fighter. The piston engine was removed and the jet engine was mounted underneath the forward fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
so that it exhausted underneath the middle of the fuselage. The deeper forward part of the fuselage gave the aircraft a "pod-and-boom" configuration. Very few changes were made to the metal fuselage, aside from adding a steel heatshield to the bottom of the fuselage, other than at the aircraft's nose. This was recontoured to house the armament of two 23 millimetre (0.905511811023622 in) Nudelman-Suranov NS-23
Nudelman-Suranov NS-23
The NS-23 was a aircraft cannon designed by A. E. Nudelman, A. Suranov, G. Zhirnykh, V. Nemenov, S. Lunin, and M. Bundin during World War II as a replacement for the Volkov-Yartsev VYa-23 cannon. It entered service in 1944...
autocannon
Autocannon
An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...
, an additional fuel tank above the engine and attachment points for the engine. 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
Spar (aviation)
In a fixed-wing aircraft, the spar is often the main structural member of the wing, running spanwise at right angles to the fuselage. The spar carries flight loads and the weight of the wings whilst on the ground...
into an inverted U-shape to clear the engine. The vertical stabilizer
Vertical stabilizer
The vertical stabilizers, vertical stabilisers, or fins, of aircraft, missiles or bombs are typically found on the aft end of the fuselage or body, and are intended to reduce aerodynamic side slip. It is analogical to a skeg on boats and ships.On aircraft, vertical stabilizers generally point upwards...
was slightly enlarged, but the tail plane was unmodified. The conventional landing gear
Conventional landing gear
thumb|The [[Piper PA-18|Piper Super Cub]] is a popular taildragger aircraft.thumb|right|A [[Cessna 150]] converted to taildragger configuration by installation of an after-market modification kit....
was also unmodified other than the tail wheel which now used several steel leaf spring
Leaf spring
Originally called laminated or carriage spring, a leaf spring is a simple form of spring, commonly used for the suspension in wheeled vehicles...
s as shock absorbers. The Yak-Jumo carried a total of 590 kilograms (1,300.7 lb) of fuel.
Taxi
Taxiing
Taxiing refers to the movement of an aircraft on the ground, under its own power, in contrast to towing or push-back where the aircraft is moved by a tug...
tests began in October 1945, but the heatshield proved to be too short and the heat from the engine exhaust melted the duralumin
Duralumin
Duralumin is the trade name of one of the earliest types of age-hardenable aluminium alloys. The main alloying constituents are copper, manganese, and magnesium. A commonly used modern equivalent of this alloy type is AA2024, which contains 4.4% copper, 1.5% magnesium, 0.6% manganese and 93.5%...
skin of the rear fuselage as well as the rubber tire
Tire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
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 TsAGI
TsAGI
TsAGI is a transliteration of the Russian abbreviation for Центра́льный аэрогидродинами́ческий институ́т or "Tsentralniy Aerogidrodinamicheskiy Institut", the Central Aerohydrodynamic Institute....
for full-scale windtunnel 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 770 kph at sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
and a speed of 850 kph at an altitude of 5000 metres (16,404.2 ft). It should be able to climb to that altitude in four and a half minutes or less and it should have a range of 500 kilometres (310.7 mi) at 90% of maximum speed. Two prototypes were to be ready for flight testing on 1 September.
According to aviation historians Bill Gunston
Bill Gunston
Bill Gunston OBE FRAeS is one of the most internationally respected and published aviation and military authors. He flew with Britain's Royal Air Force from 1943 to 1948, and is a flying instructor. He has spent most of his adult life doing research and writing on aircraft and aviation. He is the...
and Yefim Gordon, representatives from Yakovlev and the Mikoyan-Gurevich OKB 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 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 700 kilometres (435 mi) at optimum cruise speed and a reduction of the maximum ceiling
Ceiling (aeronautics)
With respect to aircraft, a ceiling is the maximum density altitude an aircraft can reach under a set of conditions.The word ceiling can also refer to the height of the lowest obscuring cloud layer above the ground.-Service ceiling:...
to 14000 metres (45,931.8 ft). 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
Soviet air show
In the life of Soviet Union, air shows were a highly regarded type of parade, almost always of military nature. They happened on various occasions and anniversaries, in many locations across the country, but if one would want to point one most notable air show, it would be the Tushino Air Show...
flyby
Flyby
Flyby may refer to:* Flypast or flyover, a celebratory display or ceremonial flight* Planetary flyby, a type of interplanetary spacecraft mission* Gravity assist, a spaceflight maneuver* "Fly by II", a single released by the UK band Blue...
. The day after the aerial display, Joseph Stalin
Joseph Stalin
Joseph Vissarionovich Stalin was the Premier of the Soviet Union from 6 May 1941 to 5 March 1953. He was among the Bolshevik revolutionaries who brought about the October Revolution and had held the position of first General Secretary of the Communist Party of the Soviet Union's Central Committee...
summoned Artem Mikoyan and Aleksandr Yakovlev
Alexander Sergeyevich Yakovlev
Alexander Sergeyevich Yakovlev was a Soviet aeronautical engineer. He designed the Yakovlev military aircraft and founded the Yakovlev Design Bureau. -Biography:...
to his office and ordered that each OKB build 15 aircraft to participate in the 7 November parade in Red Square
Red Square
Red Square is a city square in Moscow, Russia. The square separates the Kremlin, the former royal citadel and currently the official residence of the President of Russia, from a historic merchant quarter known as Kitai-gorod...
commemorating the anniversary of the October Revolution
October Revolution
The October Revolution , also known as the Great October Socialist Revolution , Red October, the October Uprising or the Bolshevik Revolution, was a political revolution and a part of the Russian Revolution of 1917...
. Factory No. 31 in Tblisi 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 armor, were provided with an enlarged fuel tank in lieu of armament, and had an incomplete avionics
Avionics
Avionics are electronic systems used on aircraft, artificial satellites and spacecraft.Avionic systems include communications, navigation, the display and management of multiple systems and the hundreds of systems that are fitted to aircraft to meet individual roles...
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 May Day
May Day
May Day on May 1 is an ancient northern hemisphere spring festival and usually a public holiday; it is also a traditional spring holiday in many cultures....
flypast in Moscow in 1947. A total of 280 Yak-15s were produced through the end of the year, exclusive of prototypes.
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 was limited to a redesigned forward fuselage that accommodated an additional cockpit for the trainee where the armament used to be and a common, sideways-opening, canopy. 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.
On 29 April 1946, five days after the Mikoyan-Gurevich I-300
Mikoyan-Gurevich MiG-9
The Mikoyan-Gurevich MiG-9 was the first Soviet turbojet fighter developed by Mikoyan-Gurevich in the years immediately after World War II. It used reverse-engineered German BMW 003 engines...
and the Yak-Jumo made their first flights
Maiden flight
The maiden flight of an aircraft is the first occasion on which an aircraft leaves the ground of its own accord. This is similar to a ship's maiden voyage....
, the Council of Ministers ordered that the Yakovlev OKB begin design of a new version of 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
Empennage
The empennage , also known as the tail or tail assembly, of most aircraft gives stability to the aircraft, in a similar way to the feathers on an arrow...
was enlarged and an ejection seat was fitted. The back of the seat was armored and the pilot was also protected by a bulletproof windscreen. The entire canopy was also redesigned to accommodate the new windscreen. The wings were too thin to house the landing gear so they were redesigned to retract into the fuselage. Two versions of the wings were considered for the modified aircraft, but the 15 square metres (17.9 sq yd) wings were chosen. At an altitude of 5000 meters, the Yak-17-RD10, as the new fighter was designated, was expected to have a top speed of 822 km/h (510.8 mph); 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
thumb|The [[Piper PA-18|Piper Super Cub]] is a popular taildragger aircraft.thumb|right|A [[Cessna 150]] converted to taildragger configuration by installation of an after-market modification kit....
was already deemed obsolete.
One Yak-15 was used to test a prototype aerial refueling system in 1949, although the installation on the fighter and the Tupolev Tu-2
Tupolev Tu-2
|-See also:-References:NotesBibliography* Bishop, Chris. The Encyclopedia of Weapons of WWII: The Comprehensive Guide to Over 1,500 Weapons Systems, Including Tanks, Small Arms, Warplanes, Artillery, Ships, and Submarines. New York: Sterling, 2002. ISBN 1-58663-762-2.* Ethell, Jeffrey L. Aircraft...
bomber used as the tanker were both dummies to test procedures and fit.
Variants
Yakovlev 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.
Yakovlev Yak-17-RD-10
- An experimental version of the Yak-Jumo aircraft incorporating improved aerodynamics, an ejection seat and protection for the pilot. Only one built, but never flown.