Solid Rocket Motors

History of Solid Rocket Motors

The first solid rocket motor (SRM) designed by Yuzhnoye was a 15D15 main motor for the first stage of the 8K99 missile. The motor development started in 1963.

The first firing of the 15D15 motor was conducted in April 1965.

However, in October 1969, development of the 8K99 missile was stopped regardless of a series of completely successful launches. The experience in SRM development allowed working on new advanced approaches to the definition of the optimum configuration of future main solid rocket motors.

In 1969, Yuzhnoye started the development of the 15Zh43 ICBM and its first-stage motor, the 15D122.

A number of breakthrough technologies were proposed for the motor design:

• Combined casing with a fiber-glass longitudinal-circumferential wound pipe and metal motor heads
• Case-bonded block of solid butyl-rubber propellant
• Central fixed nozzle partly submerged into the combustion chamber, with thrust vector control provided by injecting hot chamber gas into the submerged diverging section of the nozzle.

The 15D122 motor firing tests demonstrated the motor performance and characteristics of the thrust vector control system based on the hot-injection technique.

In this period, Yuzhnoye developed steering SRM for deployment of objects in space. The 15D161, 15D171, and 15D221 motors featured increased running time and control forces. The motors used end-burning charges made of metal-free propellant mixture with an original design of case bonding and a unique configuration of the seal in bearings of the rotating nozzles.

The next work Yuzhnoye performed in the SRM design was the development of the 3D65 main motor for the first stage of the 3M65 naval missile (designed by Makeyev design bureau). The motor design incorporated the most advanced engineering solutions:

• All-wound cocoon casing with a load-bearing shell made of high-strength organic fiber and embedded parts made of titanium alloy
• Case-bonded charge of high-energy butyl-rubber propellant
• Fixed nozzle with a three-axis thrust vector control system based on the hot-injection technique
• A number of engineering solutions determined by the specifics of using the motor in
• the naval missile (for both above-water and underwater launches).

In 1982, the 3D65 motor was accepted for series production.

In the mid-1970s, Yuzhnoye started developing main solid rocket motors for a silo-based 15Zh44 ICBM and a rail-mobile 15Zh52 ICBM: the 15D206 motor for the first stage and the 15D207 motor for the second stage.

To reduce the scope and period of development tests, the 15D206 motor was designed as a complete analog of the 3D65 motor. The modifications included increased thrust/consumption performance, increased throat diameter, and increased chamber pressure.

The following new technologies were used in the 15D207 motor:

• Fixed nozzle with an extendable high-altitude exit cone
• Carbon-carbon composite materials in the throat liner
• Formulation of propellants with higher energy characteristics
• Block of solid propellant with high chamber volumetric loading efficiency.

Ground tests of the motors started in 1979.

However, in 1983, it was decided to stop the development of the 15Zh44 and 15Zh52 missiles and use them as the basis for the 15Zh60 and 15Zh61 missiles with higher performance characteristics and better nuclear hardness.

A new motor, 15D290, was designed for the second stage of rail-mobile 15Zh61 missiles. Better performance of the motor was attained by using a new high-energy propellant mixture and making a number of design decisions to increase the motor’s nuclear hardness.

In the 15Zh60 missile, the first- and second-stage main motor requirements necessitated the development of a fundamentally new motor, 15D305, for the first stage and the upgrade of the 15D339 motor for the second stage.

The 15D305 motor design was based on the following unique technologies:

• High-energy propellant based on cyclotetramethylene tetranitramine (octogene)
• Cocoon casing
• Central swiveling nozzle with a one-piece throat liner made of 3D reinforced carbon-carbon material.

For the 15D339 motor, a multifunctional coating to protect the casing against all nuclear effects was developed; mass efficiency of the motor and erosion resistance of the nozzle were improved.

In 1986-1988, development tests of the 15D290, 15D305, and 15D339 motors were completed, and series production started.

In 1988, Yuzhnoye design office was tasked with developing the 15Zh65 ICBM first-stage propulsion system, the 15D365.

The 15D365 motor design features include:

• Block of propellant with a swiveling control nozzle, following a circular motion pattern
• Organic plastic cocoon casing
• Case-bonded octogene-based propellant mixture.

Five firing tests were conducted, and the 15D365 motor was accepted for flight tests. However, due to collapse of the Soviet Union, all work on the 15D365 in Yuzhnoye was shut down.

Besides main and steering motors, Yuzhnoye developed 82 types of small motors, pressure accumulators, and gas generators, which were used for a broad range of applications:

• Missile ‘mortar’ launch
• Missile ‘mortar’ staging
• Missile ‘wag’ during a mortar launch
• Nose-cone inflatable tip geometry change
• Increase of a main motor nozzle altitude capability
• Separation and removal of various objects away from the missile trajectory
• Missile parts flight control
• Ejection of objects from the missile and support a specified velocity of their flight
• Spin stabilization.

Many years of successful operation have proven high reliability and high operating environment resistance of the developed SRM.

Basic specifications of main motors

Name	Vacuum thrust, kgf	Propellant	Vacuum specific impulse, kgf?s/kg	SRM loaded mass, kg	Missile/Launch Vehicle
15D15	70	PEKA-181D mixture	265,0	20,0	8K99 (SS-X-15) missile first-stage steering motor
3D65	205,8	Т-9BK-8E mixture	274	52,65	3М-65 naval missile second-stage steering motor
15D206	235,7	Т-9BK-8E mixture	271,2	52,45	15Zh43 and 15Zh52 (SS-24 Mod 1) missile first-stage steering motor
15D207	142,8	OPAL mixture	291,2	32,2	15Zh43 and 15Zh52 (SS-24 Mod 1) missile second-stage steering motor
15D290	145,7	START mixture	297,5	32	15Zh61 (SS-24 Mod 3) missile second-stage steering motor
15D339	147,3	START mixture	296,6	32,05	15Zh60 (SS-24 Mod 2) missile second-stage steering motor
15D305	310,8	OPAL mixture	280	51,57	15Zh60 (SS-24 Mod 2) missile first-stage steering motor
15D365	145	OPAL mixture	283	27,55	15Zh65 Universal (SS-X-27) missile first-stage steering motor

Basic specifications of post-boost motors

Name	Vacuum thrust, kgf	Propellant	Vacuum specific impulse, kgf?s/kg	SRM loaded mass, kg	Missile
15D171	260	T-9BKN-9K cryogenic mixture	232,0	250	15А15, 15А16 missiles
15D161	780		229,0	940	15А14 missile
15D221	910		234,5	1343

Basic specifications of small SRM

Propellant	Composite propellant with a burning temperature of 1200 to 3300°K and aluminum content of 3 to 18% Ballistite (bibasic) propellant with a burning temperature of 1600 to 2800°K
Charge mass, kg	0.006 to 120
Bonding type	Mixture: inserted and case-bonded Ballistite propellant: inserted and glued into a heat-shielding barrel
Motor case material	High-strength steel, aluminum alloy, titanium alloy
Configuration	Classic design: straight or deflected nozzle Skewed nozzle Single-nozzle, two-nozzle, four-nozzle configuration with a plume spreader (for cartridge-pressure accumulator) Segner wheel shaped Ignition on nozzle side Ignition from electrical and mechanical pyrocartridges
Total thrust impulse, kgf?s	5 to 6 000
Thrust, kgf	7 to 16 680
Running time, s	0.1 to 60
Thrust (consumption) variation diagram shape	Rectangular Degressive, stepped Progressive ( 3-20 times) Thrust reversal with frequency of 15 Hz

Управляющий двигатель для ракеты-носителя

Двигатель предназначен для создания управляющих усилий по крену в процессе полета 1-й и 2-й ступеней РН. Управляющие усилия создаются благодаря последовательного (поочередного) открытия-закрытия сопел двигателя с помощью электромагнитных двухкаскадных клапанов.

Launch vehicle Steering motor

Thrust per nozzle, not less than, kgf	30
Running time, not less than, s	75
Solid charge weight, kgf	16
Motor weight, kgf	35
Maximum valve switching frequency, Hz	5-10