Kerosene Usage in Space Rockets

When people think of space rockets they tend to think of exotic fuels such a hydrogen or hypergolic propellants such as hydrazine, however one of the most frequently used rocket fuels today and through space exploration history is in fact a refined form of kerosene called RP-1. Often referred to as Rocket-Propellant-1. RP-1 is used first-stage boosters of the world most frequently used rocket the Soyuz, which ferries astronauts to the international space station. And you got many commercial launch vehicles (whole rocket assembly except the payload) such as Atlas using it for first stage. The most used commercial rocket today the Falcon 9, uses only RP-1 in all stages.

Uh, Oh. Some problems here. For starters, rockets going into space rarely if ever use kerosene. You are confusing this with jet engine which DO use kerosene (they call it JP4 and such) AND atmospheric oxygen.

Jet engines and rocket engines do have a lot in common. A rocket engine just doesn’t have a part that compresses air, rather it gets oxygen typically in a liquid form from a tank. In fact one of the more famous rocket engine designers Nikolai Dmitriyevich Kuznetsov who designed the NK-15 and later NK-33, had a jet engine design background. He was brought onboard to help develop engines for the Soviet N-1 moon rocket in the 60s. He made perhaps the most impressive kerosene rocket engines ever built. It was an oxygen rich combustion engine which in the west was believed impossible to build.

In fact after the cold war Americans were so impressed by these engines that they decided to use the RD-180 which was derived from these engines in the Atlas V rockets. That is the source of the problems during the Crimean crisis. The US could not completely boycot Russia because American space industry depended on these Russian built kerosene rocket engines.

IIRC, the Saturn five uses liquid hydrogen and liquid oxygen. Various boosters use Thiokol (sp?).

I think the source of confusion because the Space Shuttle famously used liquid Hydrogen/LOX propellant, along with solid propellant boosters. Thiokol I believe made the sold propellant.

However the Saturn V, used in the Apollo program used 5 large kerosene rocket engines for its first stage called RF-1 developed by the Rocketdyne corporation. F-1 is the largest rocket engine of any kind ever built.

Now one may wonder why so many different fuel choices? Why kerosene instead of hydrogen? I recommend reading my story on rocket propellants and rocket engines, which goes into more details on why you would pick one kind of propellant over another.

And the difficulties of starting and stopping a nuclear rocket are much exaggerated. But yes, to get off earth, you most likely need chemical rockets.

The difficulty is not really in shutting it off, you could just use something like control rods for that. However the issue which all nuclear reactors face is to cool down. Look inside at a nuclear reactor facility and use see large pools of water where spent fuel rods sit cooling off. They need weeks to cool off the excess heat.

Nuclear submarines are somewhat more lucky in that they are surrounded by water they can use for cooling. Yet the needs for cooling is massive enough that one of the ways they can be spotted is the large thermal trace they leave.

Space rockets don’t have that luxury. They are not surrounded by any kind of mass which can be used for cooling. So you are completely dependent on using your propellant for cooling. If somebody is an idiot and leaves the reactor on for too long, you may not have enough propellant left to cool it and you end up melting your whole spacecraft.

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Geek dad, living in Oslo, Norway with passion for UX, Julia programming, science, teaching, reading and writing.

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