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Country of origin USSR
Date 1962–1967
First flight 1966-11-28 (Kosmos 133)
Designer OKB-2, Anton Tavzarachvili
Application Spacecraft main propulsion
Predecessor S5.4
Successor KTDU-426
Status Retired
Liquid-fuel engine
Propellant AK27I / UDMH
Mixture ratio 1.85
Cycle gas generator
Chamber S5.60: 1
S5.35: 2
Thrust (vac.) S5.60:4.09 kN (920 lbf)
S5.35:4.03 kN (910 lbf)
Chamber pressure S5.60:3.92 MPa (569 psi)
Isp (vac.) S5.60:278 seconds
S5.35:270 seconds
Burn time 500 seconds
Restarts 25
Length 1.1 m (43 in)
Diameter 1.5 m (59 in)
Dry weight 305 kg (672 lb)
Used in
Soyuz from 7K-OK to 7K-T and Progress 7K-TG
References [1][2][3][4][5][6]

The KTDU-35 (GRAU Index 11D62) was a Soviet spacecraft propulsion system composed of two liquid rocket engines, the primary, S5.60 (SKD) and the secondary S5.35 (DKD), fed from the same propellant tanks. Both engines burn UDMH and AK27I in the gas generator cycle.[4] It was designed by OKB-2, the famous Isaev Design Bureau, for the original Soyuz programme.[3]

Within the Soyuz and Progress, the SKD is the primary engine, the DKD is the backup engine for main orbital correction and de-orbit operations, the engine generate 4.09 kN (920 lbf) (SKD) or 4.03 kN (910 lbf) (DKD) of thrust with a specific impulse of 278 seconds and 270 seconds, respectively. The SKD nozzle is fixed in the aft of the craft, and the dual DKD nozzles are on either side, the spacecraft attitude system (DPO) is responsible for pointing the vehicle in the correct direction and keep it that way during SKD burns.[7]


This engine has been used in three variants:

  • S5.53: Orbital correction engine for the lunar version of the Soyuz.[4][3]
  • S5.60 (AKA KTDU-35 GRAU Index 11D62): Version for the LEO version of the Soyuz.[4][3]
  • S5.66 (AKA KTDU-66): Maneuvering engine version for the Salyut 1 and Salyut 4 stations. Increased burn time to 1000 seconds and increased number of starts. Also was composed of primary and secondary engines.[4][8]

See also[edit]


  1. ^ Brügge, Norbert. "Spacecraft-propulsion blocks (KDU) from Isayev's design bureau (now Khimmash)". B14643.de. Archived from the original on 2015-06-02. Retrieved 2015-06-02. 
  2. ^ "Soyuz". Rocket and Space Technology. Retrieved 2015-07-08. 
  3. ^ a b c d "KTDU-35". Encyclopedia Astronautica. Retrieved 2015-07-25. 
  4. ^ a b c d e "Основные двигатели разработки КБХМ" [The main engines produced by KbKhA] (in Russian). Retrieved 2015-07-25. 
  5. ^ Pillet, Nicolas. "Le système de propulsion du vaisseau Soyouz" [The propulsion system of the Soyuz spacecraft] (in French). Kosmonavtika.com. Retrieved 2015-07-14. 
  6. ^ McDowell, Jonathan. "5.2: Russian engines". Jonathan Space Report. Retrieved 2015-07-25. 
  7. ^ Chertok, Boris (May 2009). "Chapter 18 – Birth of the Soyuzes". Rockets and People Vol. 3 – Hot Days of the Cold War (PDF). Volume 3 (NASA SP-2006-4110). NASA. p. 562. ISBN 978-0-16-081733-5. Retrieved 2015-07-15. 
  8. ^ "KTDU-66". Encyclopedia Astronautica. Retrieved 2015-07-25. 

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