RD-0109

The RD-0109 is a rocket engine burning liquid oxygen and kerosene in a gas generator combustion cycle. It has single nozzle and is an evolution of the RD-0105. It was the engine used on the Vostok Block-E that launched Yuri Gagarin to orbit.

After the success of Sputnik 1, Korolev sent series of letters to the Central Committee of the Communist Party of the Soviet Union proposing a bold plan to send robotic spacecraft to Mars and Venus. As part of such plan, a fourth stage was needed to enhance the three stage R-7 rocket and enable it to send useful payloads to those high energy destinations. This fourth stage was called Block-E, and its development started during 1958.

Korolev's OKB-1 design bureau initially competed two projects for the Block-E propulsion: 8K72, using the S.A. Kosberg's OKB-154 RD-0105, and the 8K73, using Glushko's OKB-456 RD-109 engine. Due to the complication of developing that latter, Kosberg got the contract.

Since the February 20, 1958 order of development, it took nine months to develop the engine. It was done by using RD-0102 assemblies and combustion chamber. Fifty eight static tests were conducted with 27 engines.

Between 1959 and 1960 the engine was modified to improve reliability for crewed flight. Thrust was also increased 2%, thanks to improved injection elements. It also introduced an innovation attributed to S.A. Kosbergs in its construction, that has been a staple of Soviet (and later Russian) engines. It used a corrugated metal construction for the cooling jackets, with the lower section of the nozzle lacking an external liner, to save weight. This led to a 9.3% weight reduction even with the increased thrust. This new version was christened as the RD-0109 and entered service on the December 22, 1960, launch of a (Vostok) spacecraft aboard a Vostok-K 8K72K.

The RD-0109 is the basis for the Brazilian Space Agency L75 engine project.

While the first launches for Sputnik 1 satellites could be done with the two stage booster Sputnik, to achieve escape velocity required by the Luna programme, a third stage was needed. The task of developing the specified engine was entrusted to OKB-154 (KBKhA), which did the job in 9 months. The engine received intra name RO-5.

The first flight of a Luna 8K72, which included the new Block-E stage propelled by the RD-0105 was on September 23, 1958. It was supposed to launch the Luna E-1 No.1 probe, but ended 92 seconds after launch when the rocket broke up from longitudinal vibration, causing the strap-ons to separate from the vehicle, which then crashed downrange. Neither was successful the second flight of a Luna 8K72 (October 11, 1958), which was to launch the Luna E-1 No.2 probe and ended 104 seconds after launch when the rocket again disintegrated from vibration. The third flight of a Luna 8K72 (December 4, 1958), which was to launch the Luna E-1 No.3 probe, also ended 245 seconds after launch when the Block-I core stage shut down from loss of engine lubricant.