Technical data
Type	Yak-25K-75
Function	Interceptor
Year	1956
Crew	2
Engines	2*2000kg RD-5A
Length	15.67m
Height	?m
Wingspan	10.94m
Wing area	28.95m2
Empty weight	?kg
Loaded weight	8830kg
Wing Load (kg/m2)	305
Thrust to Weight	0.45
Speed at 5000m	1000km/h
Speed at 10000m	950km/h
Landing Speed	km/h
Landing Roll	850m
Takeoff Roll	800m
Turn time	?sec
Range	?km
Flight Endurance	?h
Ceiling	13600m
Climb
5000m	2.5min
10000m	6.0min
Payload
Fuel	2650kg
Armament
Guns	None
Rockets	4*81kg K-75 (Type 129)

Yak-25K-7L with semi-active K-7L missiles at Russian Power Yak-25 page

In the early 50's few Governmental Orders were issued, aimed on creation of guided AA weapons and corresponding interceptor platforms. Several projects were under development (K-5, K-6, K-51, K-7, K-75, K-8) with radar guided and heat-seeking variants. Fighter designers received an order to accommodate those missiles and related equipment on their aircraft and evaluate the performance of new interceptors. A.S.Yakovlev (OKB-115) used modified Yak-25M as a missile platform. General designation for missile-armed Yak-25's was Yak-25K.

First missile complex to be tested (1955) was the K-5 (RS-1U) designed at OKB-2 (P.D.Grushin). Standard 'Sokol' radar of the Yak-25M was replaced by specially modified 'Izumrud' system. Cannons were removed and pairs of pylons for RS-1U missiles were installed between the fuselage and engine nacells on each side. This variant received designation Yak-25K-5.

Trials were performed in parallel with A.I.Mikoyan/M.I.Gurevich MiG-17PF (SP-6). Both Yak-25K and MiG-17PFU were in small series production. MiG's saw much wider service with PVO until early 70's.

In the early 1956 one of series Yak-25K N°1608 was modified to carry K-75 (Product 129) missile (OKB-134, I.I.Toropov). Yak-25K-75 had modified 'Izumrud' radar, improved ASP-3NM optical sight and modified fuel system. Aircraft was flown March 5 to July 10 1956 by pilots F.L.Abramov and E.N.Pryanichnikov (navigators G.N.Ulehin and V.N.Makarov). Twenty three flights were performed, totaling 16h34min. Aircraft with four missiles was pushed to Mach=1.07 in shallow dive. Handling was practically identical to the series Yak-25M.

Most of flights were performed with mockup weight-equivalent missiles (324kg total), only three life firings were performed in horizontal flight at altitudes 5000 and 12000m. target of the Il-28 at altitudes 5000 to 8000m could be detected at 7 to 7.5km, confident lock-on - at 4 to 4.5km. Despite trial conclusion was positive, K-75 missile system was not accepted for mass production.

Trials of Yak-25K-7L, carrying two large K-7 missiles were carried out, but this missile was also not accepted.

Yak-25K-8 with K-8 missiles at Russian Power Yak-25 page

The latest (end of 1956) of AA missile systems (and the most advanced) was K-8 (OKB-4 M.R.Bisnovat). Four aircraft were built, two of them - modified series Yak-25K-5. Yak-25K-8 carried two launch pylons (forward and backward swept pylons were explored), 'Sokol-2K' radar station optimized to work with the K-8 missiles. Flight program included 111 flight-hours, 72 of them - with missiles. 42 launches were performed, two of them - against target drone. Despite the Yak-25K-8 was the most successful of the Yak-25K family (one of four was even considered as a pre-production Yak-25SK-8 or Yak-25S), this interceptor was too late to enter production, because more advanced Yak-27 was already on the flight trials stage.

Drawing of Yak-25K missile armed variants, Russian Power

Predecessors	Modifications
Yak-25M/MG	None

---

References	Links
"Russian aircraft since 1940" by Jean Alexander, p.477-482 'Aviatsia i Vremia' Vol.6 1997	Yak-25 at the Russian Power.