S5.4

S5.4
Vostok spacecraft replica at the Technik Museum Speyer, Germany. The lower conical section was the service module with the S5.4/TDU-1 engine.
Country of originUSSR
Date1959-1961
First flight1959
DesignerOKB-2, A.M. Isaev
ApplicationSpacecraft braking engine
SuccessorS5.35
StatusRetired
Liquid-fuel engine
PropellantAK20F / TG-02
Mixture ratio3.07
CycleGas generator
Configuration
Chamber1 main + 4 vernier
Performance
Thrust, vacuum15.83 kilonewtons (3,560 lbf)
Chamber pressure5.6 megapascals (810 psi)
Specific impulse, vacuum266 seconds
Burn time45 seconds
Propellant capacity250 kilograms (550 lb)
Dimensions
Length1.13 metres (44 in)
Diameter0.95 metres (37 in)
Dry mass98 kilograms (216 lb)
Used in
Vostok, Voskhod and Zenit
References
References[1][2][3]

The S5.4 (AKA TDU-1, GRAU Index 8D66), was a Russian liquid rocket engine burning TG-02 and AK20F in the gas generator cycle. It was originally used as the braking (deorbit) engine of the Vostok and Voskhod crewed spacecraft, and Zenit satellites, which later switched to solid motors.[4]

The engine produced 15.83 kilonewtons (3,560 lbf) of thrust with a specific impulse of 266 seconds in vacuum, and burned for 45 seconds, enough for the deorbit. It had a main fixed combustion chamber and four small verniers to supply vector control. It was housed in the service module and had two toroidal tanks for pressurization.[5][6][7]

It was designed by OKB-2, the Design Bureau led by Aleksei Isaev, for the Vostok program. The braking engine for the first crewed spacecraft was a difficult task that no design bureau wanted to take.[citation needed] It was considered critical, as a failure would have left a cosmonaut stranded in space. A solid motor was considered, but the ballistic experts predicted a 500-kilometer (270-nautical-mile) landing error, versus a tenth of that for a liquid engine. It took the coordinated efforts of Boris Chertok and Sergei Korolev to convince Isaev to accept the task.[8]

  1. ^ Cite error: The named reference b14643-isayev was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference ea-s5.4 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference kn-vostok was invoked but never defined (see the help page).
  4. ^ Okninski, Adam (2022). "Solid rocket propulsion technology for de-orbiting spacecraft". Chinese Journal of Aeronautics. 35 (3): 128–154. doi:10.1016/j.cja.2021.07.038.
  5. ^ Cite error: The named reference rsw-vostok was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference tsr-2011-04-11 was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference turner was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference chertok-ratpv3-p26 was invoked but never defined (see the help page).