Liquid-propellant Rocket - Propellants

Propellants

Thousands of combinations of fuels and oxidizers have been tried over the years. Some of the more common and practical ones are:

• liquid oxygen (LOX, O₂) and liquid hydrogen (LH2, H₂) – Space Shuttle main engines, Ariane 5 main stage and the Ariane 5 ECA second stage, the first and second stage of the Delta IV, the upper stages of the Ares I, Saturn V, Saturn IB, and Saturn I as well as Centaur rocket stage, the first stage and second stage of the H-II, H-IIA, H-IIB
• liquid oxygen (LOX) and kerosene or RP-1 – Saturn V, Zenit rocket, R-7 Semyorka family of Soviet boosters which includes Soyuz, Delta, Saturn I, and Saturn IB first stages, Titan I and Atlas rockets
• liquid oxygen (LOX) and alcohol (ethanol, C₂H₅OH) – early liquid fueled rockets, like German (World War II) A4, aka V-2, and Redstone
• liquid oxygen (LOX) and gasoline – Robert Goddard's first liquid-fuel rocket
• T-Stoff (80% hydrogen peroxide, H₂O₂ as the oxidizer) and C-Stoff (methanol, CH₃OH, and hydrazine hydrate, N₂H₄•n(H₂O as the fuel) – Walter Werke HWK 109-509 engine used on Messerschmitt Me 163B Komet a rocket fighterplane of (World War II)
• nitric acid (HNO₃) and kerosene – Soviet Scud-A, aka SS-1
• inhibited red fuming nitric acid (IRFNA, HNO₃ + N₂O₄) and unsymmetric dimethyl hydrazine (UDMH, (CH₃)₂N₂H₂) – Soviet Scud-C, aka SS-1-c,-d,-e
• nitric acid 73% with dinitrogen tetroxide 27% (=AK27) and kerosene/gasoline mixture (=TM-185) – various Russian (USSR) cold-war ballistic missiles (R-12, Scud-B,-D), Iran: Shahab-5, North Korea: Taepodong-2
• hydrogen peroxide and kerosene – UK (1970s) Black Arrow, USA Development (or study): BA-3200
• hydrazine (N₂H₄) and red fuming nitric acid – Nike Ajax Antiaircraft Rocket
• Aerozine 50 and dinitrogen tetroxide – Titans 2–4, Apollo lunar module, Apollo service module, interplanatary probes (Such as Voyager 1 and Voyager 2)
• unsymmetric dimethylhydrazine (UDMH) and dinitrogen tetroxide – Proton rocket and various Soviet rockets
• monomethylhydrazine (MMH, (CH₃)HN₂H₂) and dinitrogen tetroxide – Space Shuttle orbiter's Orbital maneuvering system (OMS) engines and Reaction control system (RCS) thrusters.

One of the most efficient mixtures, oxygen and hydrogen, suffers from the extremely low temperatures required for storing hydrogen and oxygen as liquids (around 20 K or −253 °C)) and low fuel density (70 kg/m³), necessitating large and heavy tanks. The use of lightweight foam to insulate the cryogenic tanks led to tragedy for the Space Shuttle Columbia's STS-107 mission, as a piece broke loose, damaged its wing and caused it to break up and be destroyed on atmospheric reentry.

For storable ICBMs and interplanetary spacecraft, storing cryogenic propellants over extended periods is awkward and expensive. Because of this, mixtures of hydrazine and its derivatives in combination with nitrogen oxides are generally used for such rockets. Hydrazine has its own disadvantages, being a very caustic and volatile chemical as well as being toxic and carcinogenic. Consequently, hybrid rockets have recently been the vehicle of choice for low-budget private and academic developments in aerospace technology. Also the RP-1/LOX combination has become a popular choice for reliable and cost-sensitive commercial spaceflight applications.