RD-0110

The RD-0110 (, and its derivatives, the RO-8, RD-0108, RD-461) is a rocket engine burning liquid oxygen and kerosene in a gas generator combustion cycle. It has four fixed nozzles and the output of the gas generator is directed to four secondary vernier nozzles to provide attitude control for the stage. It has an extensive flight history with its initial versions having flown more than 65.8119354281139 years ago.

History

OKB-154 of S.A. Kosberg was tasked with developing an engine for the unmanned Molniya Block-I stage. Thus, the RD-0107 was developed in the 1960 to 1961 period, based on the RD-0106 (GRAU Index: 8D715) engine that powered the SS-8 Sasin ICBM, also designed by OKB-154. It also leveraged the experience in the field from the Vostok Block-E RD-0105/RD-0109 development. The engine had its debut flight on 10 October 1960, and the last Molniya flight was on 22 October 1967.

For the crewed carrying Voskhod Block-I, a version of the engine that complied with the human rating 3K Regulations was needed. During 1963 OKB-154 developed this new version of the engine. Known with by the GRAU index 8D715P, the RD-0108 kept the same characteristics and performance of the RD-0107 while fully complying with the crew rating regulations. This engine had its first flight on 16 November 1963, and last flew on 29 June 1976.

Design

The RD-0110 was created in a period when KBKhA had just started to design rocket engines. After many studies, simplicity and reliability were the main drivers of the design. For this reason a single shaft integrating the LOX pump, the RG-1 pump and the turbine was chosen. To provide acceptable suction performance, the RD-0110 turbopump has a dual inlet design with back to back centrifugal impellers. This allows it to work at relatively low inlet pressures without requiring additional booster pumps. The turbine is driven by a fuel rich gas generator. The ignition system for both the gas generator and the combustion chamber is done by pyrotechnic devices. The engine control is handled by a regulator, a throttle and a set of valves. It can throttle between 100% and 90.5%, with the option of 107% for a short time in emergencies.

During development, combustion instability issues were observed. The problem was found to be intimately related to the injection system design. It was finally solved by developing an optimized bi-propellant centrifugal atomizer design. During certification testing, high frequency combustion instabilities at start up were still observed. Even though the start instabilities were relatively rare at 1 in 60 to 80, and only on acceptance bench, great effort was made to eliminate the issue. Thanks to acoustic studies and modelling, a solution was found. Six combustible longitudinal felt ribs were placed at the inner surface of the combustion chamber and this solved the issue permanently.

The RD-0110 uses fuel as coolant for the regenerative cooling system. As most other Soviet designs, it uses a corrugated metal construction for the cooling jackets. The thrust chamber and upper nozzle sections has the corrugated metal sandwiched between an inner and outer metal layers. The lower section of the nozzle has no external lining, exposing the corrugated jacket to save weight. All these sections use steel for construction. Given the extreme temperatures at the throat section, this part is made of copper alloy with milled channels and an external lining. A separate film cooling system is implemented though a different manifold and is injected though a circular slot upstream of the throat.

country of origin	Soviet Union · Russia
first date	1965-10-05
designer	Chemical Automatics Design Bureau
manufacturer	Voronezh Mechanical Plant
purpose	Upper stage engine
associated	Current: Soyuz-2.1a Retired: Molniya-M and most Soyuz family rockets
predecessor	RD-0108
successor	RD-0124
status	In production
type	liquid
fuel	RG-1
oxidiser	LOX
mixture ratio	2.2
cycle	Gas-generator
combustion chamber	4 main, 4 vernier thruster
thrust(vac)	298.03 kN
thrust to weight	74.36
chamber pressure	6.8 MPa
specific impulse vacuum	325 isp
burn time	250 seconds
length	1575 mm
diameter	2240 mm
dry weight	408.5 kg
used in	Molniya-M Block-I and on most Soyuz Block-I

History

Design

Production

Versions

See also

External links

References