RD-8

The RD-8 (Russian: РД-8 and GRAU Index: 11D513) is a Ukrainian liquid propellant rocket engine burning LOX and RG-1 (a rocket grade kerosene) in an oxidizer rich staged combustion cycle.[5][6] It has a four combustion chambers that provide thrust vector control by gimbaling each of the nozzles in a single axis ±33°.[2] It was designed in Dnipropetrovsk by the Yuzhnoye Design Bureau as the vernier thruster of the Zenit (GRAU: 11K77) second stage.[7] As such, it has always been paired with the RD-120 engine for main propulsion.[8][1]

RD-8 (РД-8)
Country of originSoviet Union
First flightApril 13, 1985
DesignerYuzhnoye Design Bureau
ManufacturerYuzhmash
ApplicationSecond Stage Vernier
Associated L/VZenit
SuccessorRD-809M
StatusIn Production
Liquid-fuel engine
PropellantLOX / RG-1
Mixture ratio2.4
CycleStaged Combustion
Configuration
Chamber4
Performance
Thrust (vac.)78.45 kN (17,640 lbf)
Chamber pressure7.747 MPa (1,123.6 psi)
Isp (vac.)342 s (3.35 km/s)
Burn time1100 s
Gimbal range±33°
Dimensions
Length1,500 mm (59 in)
Diameter4,000 mm (160 in)
Dry weight380 kg (840 lb)
Used in
Zenit family second stage
References
References[1][2][3][4][5][6]

It can only be started once, and as a high altitude engine it has a thrust of 78.45 kN (17,640 lbf) and a specific impulse of 342 s (3.35 km/s).[5][6] It is the first ever steering engine to use the staged combustion cycle, and as such is the basis for a family of planned engines for the Mayak launch vehicle family.[3]

The engine itself is built like a hollow cylinder, with a cylindrical space in the center so the RD-120 nozzle can pass through.[9]

Derivatives

Whilst Yuzhnoye's propulsion experience had been mostly on hypergolic propellants engines, like RD-855 or RD-861, they are considered too toxic for current ecological standards.[7][8] While Yuzhnoye still offer to develop hypergolic propulsion, such as RD-843 for the Vega's AVUM stage or the Tsyklon-4 project, Yuzhnoye selected a more environmentally friendly LOX and kerosene propellant for the Mayak launch vehicle family.[3]

Not only had Yuzhnoye mastered the most complex cycle for the propellant (oxidizer rich staged combustion cycle) with the RD-8, but they had worked closely with NPO Energomash during the RD-120 program. The manufacturing is done at its sister company of Yuzhmash in Dnipropetrovsk, and the RD-120 thrust augmentation project of 2001 to 2003 had been a mixed project between the three companies.[3]

On the base of this experience, a family of derivatives engines were proposed. While the RD-801 and RD-810 are really just based on the general technology, the other members of the family are related enough that they reuse many components of the RD-8.[3] One characteristic of this family is the limitation of keeping the preburner output temperature below 500 °C (932 °F).[3]

  • RD-805 (or RD-802): A proposed upper stage engine of just 19.62 kN (4,410 lbf) of thrust, it would use a single chamber of the RD-8.[10] While many new components would be required, it is considered a low technological risk since it only needs smaller versions of already developed component. [3]
  • RD-809 (sometimes identified as RD-809M): It is an RD-8 re arranged to minimize its diameter. It would use practically every single component of the RD-8, but arranged without the big hollow section in the middle. It was a proposed engine for a proposed liquid upper stage of the Antares rocket, then named Taurus II.[3] It would be capable of five engine burns in a single mission.[11]
  • RD-809K: A proposed single nozzle version of the RD-8. It would mix most principal elements of the RD-8 like the turbopumps with a main combustion chamber and nozzle adapted from the RD-861K.[3][12] It would be capable of 4 starts in a single mission.[12] It is expected to be used in a dual engine configuration in the Mayak upper stage.[3]
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References
  1. Gunter Dirk Krebs (2015-12-15). "Zenit family". Gunter's Space Page. Retrieved 2016-07-14.
  2. Brügge, Norbert (2016-07-11). "Ukrainian space-rocket and missile liquid-propellant engines". B14643.de. Retrieved 2016-07-14.
  3. Degtyarev, A . V.; Shulga, V . A.; Zhivotov, A . I.; Dibrivny, A . V. (2013). "Создание семейства кислородно-керосиновых жидкостных ракетных двигателей на базе отработанных технологий для перспективных ракет-носителей гп «Кб «Южное»" [The development of LOX - kerosene liquid rocket engines family for perspective launch vehicles of SDO Yuzhnoye based on proven technologies] (PDF). Авиационно - космическая техника и технология (in Russian). National Aerospace university them. NE Zhukovsky. 2013 nr. 01 (98): 44–50. ISSN 1727-7337. Archived from the original (PDF) on 2016-08-16. Retrieved 2016-07-14.
  4. "RD-8". Defense Industry Of Ukraine Products And Services. Archived from the original on 2016-08-18. Retrieved 2016-07-14.
  5. "RD-8". Yuzhnoye. Archived from the original on 2016-07-09. Retrieved 2016-07-14.
  6. "Liquid rocket engine RD-8". Yuzhmash. Retrieved 2016-07-14.
  7. "Двигатели 1944-2000: Аавиационные, Ракетные, Морские, Промышленные" [Aviadvigatel 19442-2000: Aviation, rocketry, naval and industry] (PDF) (in Russian). pp. 265–266. Retrieved 2015-07-25.
  8. Hendrickx, Bart; Vis, Bert (2007-10-04). Energiya-Buran: The Soviet Space Shuttle (UK 2007 ed.). Springer. p. 80. ISBN 978-0-387-69848-9.
  9. Zak, Anatoly (2013-01-31). "Stage II of the Zenit rocket". Russian Space Web. Retrieved 2016-07-14.
  10. "RD-802". Defense Industry Of Ukraine Products And Services. Retrieved 2016-07-14.
  11. "RD-809". Yuzhnoye. Retrieved 2016-07-14.
  12. "RD-809K". Yuzhnoye. Retrieved 2016-07-14.

See also
  • RD-120 – The Zenit second stage main engine which is the companion of the RD-8 and the basis for some of its derivatives.
  • Zenit – The launch vehicle family for which the RD-8 was developed.
  • Mayak – Prospective Ukrainian launch vehicle family for which the RD-805, RD-809 and RD-809K are being developed.
  • Yuzhnoe Design Bureau - The RD-8 designer bureau.
  • Yuzhmash - A multi-product machine-building company that's closely related to Yuzhnoe and manufactures the RD-8.
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