19 July 1959, the USSR Council of Ministers decided to start developing a new projectile aircraft to arm existing and future submarines. The missile, designated P-7, should have been a further development of the P-5 developed at that time, but had a different purpose. The task of the new rocket was the destruction of areal coastal and concentrated surface targets with previously known coordinates. The required flight range was 1000 km. The flight was proposed to be carried out at an altitude of 100 m above the surface. New development weapons assigned OKB-52, headed by V.N. Chelomeem. This organization has already been involved in several naval missile projects. fleet, including the P-5 missile, which was proposed to be used as the basis for the P-7.
The main design tasks of the P-7 project were the improvement of the airframe and the power unit of the base rocket, as well as the development of updated control systems. According to some data, the second task was proposed to be solved by borrowing instruments from the P-5D rocket, which differed from the initial P-5 by enhancing certain characteristics. It was planned to increase the flight range by using a more economical engine, increasing the stock of fuel and optimizing aerodynamics. As subsequent events showed, the methods for solving the tasks were chosen correctly.
The only known image of the P-7 rocket. Photo Militaryrussia.ru
As an option of deep modernization of the existing product, the P-7 rocket was supposed to receive a glider representing modified units of the base P-5. The main element of the rocket was an elongated fuselage of high elongation with a pointed head fairing. The head part of the fuselage had a circular cross section, and under the bottom of its central part it was planned to place the air intake of the main engine. Also in the central part of the rocket was installed folding wing of a large sweep. In the tail there were all-turning stabilizers of small scope, and under the bottom was attached the keel with the rudder. In the same place there were fastenings for the starting engine dumped after development of fuel.
In the project П-7 from the previous П-5, the automatic layout of the wing was transferred. When developing the P-5 product, it was decided to use special devices with which it was possible to reduce the cross section of the rocket. In the transport position, the wing console rocket went down-inward and was placed on the sides of the fuselage, reducing the transverse envelope from 2,6 to 1,6 m. When the rocket left the launch container, the console had to be horizontal and fixed in it.
The power plant rocket P-7 based on some new units. According to reports, the turbojet cruise engine KRD-26 of the P-5 rocket was replaced by a more economical product with similar parameters. The type of new engine, unfortunately, is unknown. Data on the replacement of the starting solid-fuel engine is not available. The principles of operation of the engines remained the same: for the initial acceleration, leaving the launch canister and putting the rocket to the required height, it was proposed to use a pair of solid fuel engines attached under the fuselage tail. After the production of fuel, they were separated and the further flight was to take place with the help of a sustainer power plant.
In addition to using the new engine, it was proposed to refine the fuel system in order to increase the capacity of the tanks. The main consequence of this was an increase in the starting weight of the P-7 product to 6600 kg. For comparison, the P-5 rocket in the launch configuration weighed less than 5400 kg. Taking into account the mass of the starting engine of the order of 900-920 kg, it is possible to determine the approximate flight weight of the rocket after the separation of the accelerators. In addition, it can be established that the difference in flight weight of the P-7 and P-5 missiles was 1,2 t. Most of this mass was in the extra fuel required to bring the flight range to the required values.
The new rocket was to be equipped with an updated inertial type control system. Its main element was the autopilot AP-71. In addition, in order to more accurately determine their own coordinates and deviations from a given route, a Doppler velocity meter and a drift angle of the “Sail” type were introduced into the electronics. Such processing of control systems made it possible to significantly improve the accuracy of hitting the areal target in comparison with the P-5 in the base configuration. Recall that the KVO of this product reached the 3000 m. As for the P-5D modification, such a rocket, being equipped with a Doppler velocity and drift meter, had a greater accuracy in 2-3 compared to the base product.
The unification of the P-7 rocket with an existing product also affected launch systems. Due to the similar design, the new rocket had full compatibility with launchers designed for the use of P-5 products. For the development of commands entered into the electronic equipment of the rocket, the Start control device was developed. This device could serve as new missiles P-7, and older P-5D.
To launch new missiles, it was planned to use the existing units developed in the framework of the previous project. The basis of the launcher was a container CM-49. It was a cylindrical device with a length of about 12 m with an inner diameter of 1,65 m. The end covers of the container were equipped with seals and creamer valves for hermetic closure in the transport position, and also had actuators for lifting before launching the rocket. The front cover allowed the product to leave the container, and the engine gases had to go out through the open rear end during launch. Inside the container there were a set of rails for moving the rocket and connectors for connecting it to the carrier systems.
Having found the target with their own systems or having received external target designation (a similar opportunity appeared by the mid-sixties), the P-7 submarine carrying the rocket using the Start system had to produce commands for the autopilot and enter them into its memory. Shooting a rocket could be carried out only in the surface position. To start, it was necessary to rise to the surface, with the help of special hydraulics, remove the CM-49 container to the starting angle 15 ° and open its lids. After that, the rocket had to turn on the engines, get out of the container, spread the wing and start the flight to the specified coordinates of the target.
Due to the use of an inertial guidance system without the ability to search for a target, a rocket could fly at a relatively low altitude: the absence of target search systems made it possible not to rise to a considerable height. During the flight, the automatics had to hold the rocket at an altitude of 100 m above the surface of the water or the earth. One of the main advantages of low-altitude flight was the possibility of the enemy's air defense breaking through with subsequent successful target destruction in a given area. For the air defense systems of the early sixties, the low-altitude supersonic rocket was a very difficult goal.
The widespread use of ready-made components allowed to complete the design work in a relatively short time. By the spring of 1961, the P-7 cruise missile project was ready for the start of flight tests. The 4A stand on the proving ground near Balaclava in the Crimea, where previous P-5 missiles were tested, was supposed to become a platform for testing promising missiles. The stand had a launcher based on the CM-49 container, which completely imitated the launch vehicles of existing and future carrier submarines.
The first test launch of the P-7 rocket took place on 21 on April 1961. At the time of launch, the systems worked normally and allowed the rocket to leave the launch canister. However, shortly after the launch, an explosion occurred that destroyed the prototype. Soon the second launch was made. Until July 1962, X-NUMX P-4 missiles took off from the 10 stand. Part of the launches ended in success, but the others were abnormal. There is no exact information about the number of successes and accidents.
In the second stage of testing, it was planned to use one of the submarines available from the navy. The submarine C-158 of the 644 project became the platform for test launches of the new missile. This diesel-electric submarine was laid at the end of 1952 of the year at the plant number 112 ("Red Sormovo") and was built according to the project 613. In the last days of 1953, the boat was included in the Black Sea Fleet. In October 1958, the submarine arrived at Shipyard No. 112 for re-equipment on the new project 644. In the course of these works, two lifting installations with CM-49 containers were installed behind the fencing, of which it was proposed to launch the P-5 missiles. At the end of 1960, C-158 returned to service in the USSR Navy, and in 1962 it was transferred to the Northern Fleet.
In 1962, the C-158 submarine again went for modernization, this time it was planned to be reequipped using the new project 644-7. The purpose of this work was the installation of a “Start” fire control device and other equipment necessary for the use of P-5D and P-7 missiles. By October of the same year, the boat was again ready to go to sea and launch cruise missiles.
Submarine C-158, view of the stern. Behind the felling fence are two containers for missiles. Photo Deepstorm.ru
In October, the 1962 of the year C-158 conducted the first launch of the P-7 rocket, which launched a joint flight test. At the White Sea testing grounds, X-NUMX P-11 missile launches were carried out on various training targets. This audit phase lasted several months and ended only in the 7 year. According to some data, taking advantage of the available capabilities, the C-1963 submarine fired 158-1962 during the tests and fired not only P-63 missiles, but also other types of products: P-7 and P-5D. The composition of the on-board equipment and the maximum unification of the missiles made it possible to use all the available weapons of the family.
In November, 1964, the submarine C-158 again set sail with P-7 missiles on board. The purpose of this campaign was to conduct test trials of the rocket. Two launches were performed that demonstrated all the capabilities of the new missile system. Control tests allowed to expect the adoption of a new cruise missile for service and the deployment of its mass production.
At the end of 1964 and the first half of 1965, the command decided the fate of the P-7 product. Due to recent successes in the field of missile weapons, the prospects for the П-7 project have been the subject of controversy. This rocket was distinguished by a fairly long range, but had low accuracy, limiting the range of tasks to be solved. At the same time, by the mid-sixties, there were already notable successes in creating guidance systems for cruise missiles. Also appeared quite successful ballistic missiles intended for submarines. After analyzing the current situation, it was decided to abandon the P-7 rocket. Resolution of the Council of Ministers on the complete cessation of work on this project was issued 2 August 1965.
Together with the P-7 project, all work on advanced sea-based cruise missiles intended for firing at coastal targets was stopped. Due to the presence of success in other areas, such tasks were now proposed to be solved with the help of ballistic missiles of submarines. Such weapons differed higher performance and great prospects. In addition, it allowed to attack targets with greater efficiency. Thus, the need for cruise missiles like the P-7 was now absent.
After the P-7 project was closed, OKB-52 staff continued to work on other missiles based on the original P-5. All of them were put into service and used for various purposes. The submarine C-158, upgraded by the 644-7 project, after completing all the tests, was returned to the Black Sea Fleet, where it served up to 1982, being the carrier of the P-5, P-5D and, possibly, P-6 missiles.
The P-7 cruise missile was supposed to complement the existing P-5 products and ensure the defeat of surface and ground targets at a range of 500-1000 km. The main design tasks were successfully resolved, but the development of alternative systems prevented the adoption of the missile. As a result, the P-7 project was closed, remaining in stories as the last domestic cruise missile for submarines, intended for firing at areal targets with previously known coordinates. In the future, these tasks were assigned to other weapons.
Shirokorad A.B. Weapons of the domestic fleet. 1945-2000. - Minsk: “Harvest”, 2001