Yakovlev Yak-25

This article deals with the interceptor aircraft. For the test fighter of the same name see Jakowlew Jak-25 (1947)

Yakovlev Yak-25
Jak-25M in the Monino Museum
Type:	All-weather twin-engine interceptor
Design country:	Soviet Union
Manufacturer:	OKB Yakovlev
First flight:	June 19, 1952
Commissioning:	1955
Production time:	1954 to probably 1960
Number of pieces:	638

Jakowlew Jak-25 ( Russian Яковлев Як-25 , NATO code name Flashlight ) is the name for a twin-engine all-weather interceptor aircraft from the Experimental Design Office (OKB) Jakowlew , which was developed in the early 1950s and produced in over 600 copies. Based on this model, the Jakowlew Jak-28 was later created .

history

In 1950 the Soviet air forces requested a long-range interceptor that was suitable for night and all weather. The latter emerged victorious from the competition in which Mikoyan with the I-320 (Project R), Sukhoi with the Su-15 , Lavochkin with the La-200 and Yakovlev with the test model Jak-120 participated. The Jak-120 was the only one of the named models to have the new Axial-TL AM-5 , the other developments were powered by Radial-TL RD-45 or WK-1 . On June 19, 1952, this prototype completed its maiden flight with Valentin Volkov. After successfully completing the tests and making minor changes, the model finally went into series production in 1954 as the Jak-25 in Saratow Plant No. 292. In September 1954 the first machines left the production line and in 1955 the first air defense unit converted to this model. The Jak-25 was first presented to the public on July 3, 1955 at the traditional air parade in Tushino .

Since the originally planned onboard radar Sokol at the start of production was not yet ready for use, the machines initially received a modified RP-1D thorium - Funkmessgerät that the entire bow of the Yak-25 claimed because of its size; a total of 67 machines of this design were built. The aircraft, designed as a cantilever middle- wing aircraft, had wings swept at 45 ° with two boundary layer fences each . The tail unit was also swept.

The Jakowlew design office , which had already gained experience with tandem trolleys with the Jak-30 and Jak-1000 , adopted this design for the Jak-25.

In November 1953, the Sokol on-board radar was finally ready for use. It offered significant advantages over the RP-1 radar used in the first series ; Among other things, low-flying targets could now also be recorded. In April 1954 the device was tested in the Jak-120 and finally put into production as the RP-6. In May 1954 the state order was issued to put the Jak-25 equipped with the Sokol radar into production immediately. In fact, the production changeover lasted until January 1955. The new aircraft were now referred to as Jak-25M and at the same time received improved engines and a revised weapons and fuel system. As an experiment, some Jak-25M received the Gorizont-1 system, with which weapons could also be deployed using ground-based radar; the machines modified in this way were called Jak-25MG.

At the beginning of the fifties, parallel to the development of new aircraft, corresponding requirements were made for the development of air-to-air guided missiles , for which the suitable launch vehicles now seemed to be available. Various missile projects were under development as K-5, K-6, K-51, K-7, K-75 and K-8 and included both radio measurement and infrared guided variants. The designers of fighter aircraft have now received the order to integrate these missiles and their associated equipment into their aircraft and to test these weapon systems.

Jakowlew used modified Jak-25M as a missile carrier, whereby the general name of these missile-armed machines was Jak-25K. The first missile complex tested in 1955 was the K-5 (RS-1U) of OKB Gruschin . The Jak-25M's Sokol radar was replaced by a specially modified Isumrud system. The cannon armament was removed and a pair of pylons for the rockets were attached between the fuselage and the engine nacelles under the wings. The redesigned machine was named Jak-25K-5. The tests were carried out in parallel with the Mikojan SP-6, which was equipped with an analogue system, and proved to be successful. Both types were then manufactured in small series. The Mikoyan pattern was named MiG-17PFU and was partially used until the early 1970s.

At the beginning of 1956 a serial Yak-25M was converted to use the K-75 missile by I. I. Toporow. This Jak-25K-75 also had a modified Isumrud radar, an improved ASP-3NM sight and a revised fuel system. The flight tests began in March and showed a behavior practically identical to that of the Jak-25M. Field tests confirmed the usefulness of the missile and radar system, which allowed target engagement over a distance of several kilometers; Despite the positive results, the K-75 complex did not go into series production. Another Jak-25K-7L was tested with two large K-7 missiles, but did not go into production either. The last missile system was the K-8 from the OKB Bisnowat . Four Jak-25K-8 were created by converting the standard Jak-25K-5. They had two rocket pylons and the Sokol 2K radar, which was optimized for the K-8. Although this Jak-25K-8 was the most powerful model of the Jak-25K series, it came too late for a production launch, as the improved further development Jak-27 was already successfully in flight tests.

The Jak-25 was very popular with pilots, but became increasingly obsolete in the 1960s. Along with the MiG-19 fighter and the Tu-16 bomber, the model formed the backbone of the Soviet air force in the 1950s and early 1960s. From 1963 the gradual replacement of the Jak-25 began in the role of interceptor aircraft, the last machines were decommissioned in 1967.

From 1957, the Soviet Union also developed a single-seat high-altitude reconnaissance aircraft called Jak-25RW ( NATO code name "Mandrake"), which was modified again after a US U-2 was shot down and put into service in 1963. This was equipped with the R11-W300 engines specially modified for use at great heights . In July 1959, test pilot Vladimir Smirnow set two world height records with a Jak-25RW: 20,456 m with a 1000 kg payload and 20,174 m with a 2000 kg payload.

Versions

Jak-25RW-II in Monino

• Jak-25 - interceptor aircraft
• Jak-25F - interceptor aircraft
• Jak-25K - interceptor aircraft
• Jak-25M - interceptor aircraft
• Jak-25MG - experimental interceptor aircraft
• Jak-25P - front-end fighter
• Jak-25R - Tactical scout, also known as Jak-125
• Jak-25RM - maritime patrol aircraft
• Jak-25B - bomber, also known as Jak-125B
• Jak-25RW - high-altitude reconnaissance aircraft
• Jak-25U - trainer aircraft

Further developments were the Jak-26 , Jak-27 , which were equipped with more powerful engines and modified wings, and the Jak-28, which was also built in series .

Technical specifications

Three-sided tear

Parameter	Jak-25 (1953)	Jak-25M (1955)	Jak-25K-75 (1956)
Conception	All-weather interceptor aircraft
crew	2 men
span	10.96 m	10.94 m
length	15.67 m
height	4.35 m	k. A.	k. A.
Wing area	28.94 m²		28.95 m²
Empty mass	5,678 kg	k. A.	k. A.
Takeoff mass	normal 9,450 kg maximum 11,500 kg	normal 9,220 kg maximum 10,045 kg	8,830 kg
Wing loading	k. A.	347.00 kg / m²	305.00 kg / m²
Top speed	1,090 km / h at an altitude of 5,000 m	1,090 km / h at an altitude of 5,000 m	950 km / h at an altitude of 10,000 m, 1,000 km / h at an altitude of 5,000 m
Rate of climb	50.00 m / s	44.00 m / s near the ground	k. A.
Rise time	2.0 min at 5,000 m 5 min at 10,000 m	5.5 min at 10,000 m	2.5 min at 5,000 m 6 min at 10,000 m
Summit height	14,500 m	k. A.	13,600 m
Range	a maximum of 2,730 km	maximum 2,560 km	k. A.
Takeoff route	735 m	800 m
Landing route	800 m	850 m
Flight duration	3 h 25 min	3 h 15 min	?
Engines	two Mikulin AM-5A	two Mikulin RD-5A
power	19.6 kN each	20.0 kN each
Armament	two 37 mm MK N-37L (50 shells each)	two 37 mm MK N-37L (100 shells each)	four air-to-air guided missiles K-75

literature

• Joachim Barschin: Jakowlew's twin-beam in war and peace . In: Flieger Revue Extra . No. 8 . Möller, 2005, ISSN  0941-889X .
• Rainer Göpfert: First Soviet all-weather interceptor: Jakowlew Jak-25 . In: FliegerRevue . No. 6/2017 , p. 50-54 .

Web links

Commons : Jakowlew Jak-25  - Collection of pictures, videos and audio files

Individual evidence

1. ↑ Nikolai Jakubowitsch: Jakowlew Jak-25. Russian guard . In: Aviation Classics . No. 5/2016 . Motor Presse, Stuttgart, p. 54-59 .
2. ^ Karl-Heinz Eyermann , Wolfgang Sellenthin: The air parades of the USSR . Central Board of the Society for German-Soviet Friendship, 1967, p. 38 .
3. ↑ FAI Record ID # 14658
4. ↑ FAI Record ID # 14660