Yakovlev Yak-15
| Company type | Military aircraft |
|---|---|
| Industry | Aerospace |
| Founded | 1947 |
| Headquarters | Moscow (Yakovlev design bureau) , Soviet Union |
| Products | Jet fighter aircraft |
| Parent | Yakovlev design bureau |
The Yakovlev Yak-15 (Russian: Яковлев Як-15; NATO reporting name: Feather, USAF/DoD designation Type 2) represents a first-generation Soviet turbojet fighter crafted by the Yakovlev design bureau immediately following World War II. Its fuselage was adapted from the piston-engine Yakovlev Yak-3, modified to accommodate a reverse-engineered German Junkers Jumo 004 turbojet. Among early jet conversions, only the Yak-15 and the Swedish Saab 21R successfully transitioned from piston propulsion to jet-powered production aircraft. A total of 280 units were manufactured in 1947. Though classified as a fighter, its primary role was to train pilots experienced with piston engines to operate jet aircraft.
Development and description
On 9 April 1945, the Council of People's Commissars commissioned the Yakovlev OKB to design a single-seat jet fighter powered by a German Jumo 004 engine. To expedite development, Yakovlev based this model—initially called the Yak-3-Jumo or Yak-Jumo—on the latest Yak-3 piston fighter airframe. The piston engine was removed, and the jet engine installed beneath the forward fuselage, with exhaust exiting underneath mid-fuselage. A steel heatshield was affixed beneath the fuselage to protect it from exhaust heat. This deeper forward fuselage gave the aircraft a "pod-and-boom" appearance. Minimal modifications were made to the metal fuselage aside from reshaping the nose to house two 23-millimeter (0.91 in) Nudelman-Suranov NS-23 autocannons, an auxiliary fuel tank above the engine, and the jet engine itself. The wings remained unchanged except for removal of oil cooler air intakes and reshaping of the front wing spar into an inverted U to clear the engine. The vertical stabilizer was slightly enlarged while the tailplane stayed unaltered. Conventional landing gear was retained with modifications limited to fitting multiple steel leaf springs as shock absorbers on the tailwheel. The Yak-Jumo carried 590 kilograms (1,300 lb) of fuel.
Taxi trials commenced in October 1945 but revealed that the heatshield was insufficiently long; engine exhaust heat melted rear fuselage duralumin skin and damaged the tailwheel tire. Fixes were implemented by late December. By then, a second prototype featuring a solid steel tailwheel and enlarged tailplane had been completed. Following additional taxi tests, it underwent comprehensive wind tunnel analysis at TsAGI until February 1946. On 26 February, new performance criteria were issued by the Council of People's Commissars: maximum speeds of 770 km/h (480 mph) at sea level and 850 km/h (530 mph) at 5,000 meters (16,400 ft), climb to that altitude within four and a half minutes or less, and a range of 500 kilometers (310 mi) at ninety percent maximum speed. Two prototypes were required for flight testing by 1 September.
Concurrently, Mikoyan-Gurevich OKB was developing their MiG-9 jet fighter. According to historians Bill Gunston and Yefim Gordon, on 24 April 1946 representatives from both bureaus flipped a coin to decide which aircraft would achieve first Soviet jet flight; Yakovlev lost, resulting in his prototype performing only one circuit before landing. Factory testing concluded on 22 June; however, due to early success, on 29 April the Council of Ministers mandated two aircraft powered by domestically produced RD-10 engines (designated Yak-15 or Yak-15RD10) with revised specifications: increased range of 700 kilometers (430 mi) at optimal cruise speed and reduced ceiling of 14,000 meters (45,930 ft). Two prototypes were ordered for flight evaluation by September.
Yakovlev adapted existing prototypes for RD-10 engines with minimal issues; one participated in Tushino air show flypast in August 1946. The day following this event, Joseph Stalin summoned Artem Mikoyan and Aleksandr Yakovlev, instructing each OKB to produce fifteen aircraft for the upcoming November parade commemorating the October Revolution anniversary in Red Square. Factory No. 31 in Tbilisi was chosen due to its ongoing production of conventional Yak-3s facilitating transition to jet fighters. All fifteen units were completed before deadline but lacked armor, featured enlarged fuel tanks instead of armament, and had incomplete avionics systems. After parade cancellation, two planes were modified with single 23 mm cannons and entered State acceptance trials lasting until April 1947.
Testing uncovered several issues: thick wings inherited from Yak-3 restricted maximum speed; engine exhaust damaged airfield surfaces; cockpit smoke intrusion occurred due to kerosene and oil leaks onto engine; and operational range was limited. Nonetheless, pilots transitioning from piston fighters found the Yak-15 highly manageable, leading Soviet Air Forces (VVS) to adopt it as a conversion trainer.
Before State trials ended, production was authorized by Council of Ministers in December 1946 for fifty aircraft between January and April 1947—split evenly between single-seat fighters and two-seat trainers armed with one cannon each. Development problems delayed trainer variants; thus all initial batch units were single-seaters. Fifty aircraft participated in Moscow’s May Day flypast in 1947. Overall production reached 280 units by year-end excluding prototypes. These jets were distributed in small quantities among fighter regiments across USSR, Poland, Romania, Hungary, and Manchuria primarily as conversion trainers. Their agility also made them popular with various informal aerobatic teams during late 1940s.
The two-seat trainer prototype was first produced by Factory No.31 in autumn 1946 but did not commence factory flight tests until April 5, 1947. Differences from single-seat versions included redesigned forward fuselage housing an additional cockpit for trainees where armament had been located and a sideways-opening canopy. Initially called Yak-Jumo vyvoznoy, it later received designations such as Yak-21 or sometimes Yak-15V/Yak-15UT/Yak-21V in documentation. Further development ceased following success of tricycle undercarriage-equipped trainer variant of the Yak-17.
In 1949, one Yak-15 served as a testbed for an aerial refueling prototype system; however, installations on both this fighter and its Tupolev Tu-2 tanker counterpart were mock-ups intended solely for procedural evaluations and fit checks.
Yak-17-RD10
On 29 April 1946, shortly after the first flights of the Mikoyan-Gurevich I-300 (MiG-9 prototype) and the Yak-Jumo, the Council of Ministers directed the Yakovlev OKB to develop a new aircraft resembling the Yak-Jumo but powered by the RD-10 engine and featuring enhanced aerodynamic design. While it retained a general likeness to the original model, this version introduced completely redesigned wings with laminar flow airfoils, an enlarged tail assembly, and was equipped with an ejection seat.
The pilot’s seat included armor plating on its back, complemented by a bullet-resistant windscreen safeguarding the cockpit. The canopy was also restructured to fit this new windscreen design. Due to the slim wing profile, the landing gear could not retract into the wings and was therefore redesigned to fold into the fuselage. Both low and high wing loading configurations were evaluated, with the prototype ultimately adopting low wing loading wings measuring 15-square-meter (160 sq ft).
The Yak-17-RD10 designation was assigned to this fighter, which was projected to reach a maximum speed of 822 km/h (511 mph) at 5000 meters altitude—a marked improvement over the production Yak-15. Assembly was completed on 3 September, followed by ground testing through 26 September; however, it never achieved flight as production had already commenced on the Yak-15, whose conventional landing gear was considered outdated.[1]
Survivors
The only remaining Yak-15 is known as 'Yellow 37' and is displayed at the Vadim Zadorozhny Technical Museum near Moscow. This aircraft became part of the museum's collection after acquisition from the Yakovlev OKB's dissolved museum in 2006.[2]
Variants
Information source: OKB Yakovlev[3]
- Yak-Jumo (Yak-3-Jumo): Early prototypes of the Yak-15 series powered by captured Jumo 004 jet engines.
- Yak-15-RD10: Also called Yak-RD; initial prototypes and early production units utilizing Soviet-manufactured RD-10 engines (copies of Jumo 004), typically fitted with no or minimal armament.
- Yak-15: Production variant equipped with full weaponry.
- Yak-21: A two-seat trainer version derived from the Yak-15; only one was constructed as it was superseded by the successful trainer variant of the Yak-17.[4]
- Yak-15V: (V - Vyvozny - familiarisation trainer) An alternative designation for the Yak-21.
- Yak-15U: (U - Uchebnotrenirovochnyy - training) Another name used for the Yak-21.
- Yak-15U (Yakovlev Yak-15U-RD10): (U - uloochshenny - improved) An enhanced version featuring tricycle landing gear and external drop tanks; served as the prototype for the definitive Yak-17.
Yak-17-RD10: This experimental model bore visual similarities to the Yak-Jumo but incorporated substantial redesigns including advanced aerodynamics, pilot protection, and an ejection seat. The single prototype never flew as development ceased on 26 September 1946 during taxiing trials.[1]
Operators
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, Dmitriy 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. Sandomierz, Poland: Stratus, 2008.