The S5.4 (AKA TDU-1, GRAU Index 8D66), was a Russian

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, an ...

rocket engine A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive Jet (fluid), jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, i ...

burning TG-02 and AK20F in the gas generator cycle. It was originally used as the braking (deorbit) engine of the Vostok, Voskhod, and Zenit

spacecraft A spacecraft is a vehicle or machine designed to spaceflight, fly in outer space. A type of artificial satellite, spacecraft are used for a variety of purposes, including Telecommunications, communications, Earth observation satellite, Earth ...

, which later switched to solid engines. The engine produced of thrust with a

specific impulse Specific impulse (usually abbreviated ) is a measure of how efficiently a reaction mass engine (a rocket using propellant or a jet engine using fuel) creates thrust. For engines whose reaction mass is only the fuel they carry, specific impulse is ...

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. It was designed by OKB-2, the Design Bureau led by Aleksei Isaev, for the Vostok program. The braking engine for the first manned spacecraft was a difficult task that no design bureau wanted to take. It was considered critical, as a failure would have left a cosmonaut stranded in space. A solid engine was considered, but the ballistic experts predicted a landing error, versus a tenth of that for a liquid engine. It took the coordinated efforts of Boris Chertok and

Sergei Korolev Sergei Pavlovich Korolev (russian: Сергей Павлович Королёв, Sergey Pavlovich Korolyov, sʲɪrˈɡʲej ˈpavləvʲɪtɕ kərɐˈlʲɵf, Ru-Sergei Pavlovich Korolev.ogg; ukr, Сергій Павлович Корольов, ...

to convince Isaev to accept the task.

References

External links

KB KhIMMASH Official Page ''(in Russian, Archived)''
Rocket engines of Russia Rocket engines of the Soviet Union Rocket engines using hypergolic propellant {{rocket-stub