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Applied Chemistry and Physics
Published in Robert A. Burke, Applied Chemistry and Physics, 2020
In contemporary usage, the terms “hypergolic” or “hypergolic propellant” usually mean the most common such propellant combination, dinitrogen tetroxide plus hydrazine and/or its relatives monomethylhydrazine and unsymmetrical dimethylhydrazine.
Launch Vehicles, Propulsion Systems, and Payloads
Published in Janet K. Tinoco, Chunyan Yu, Diane Howard, Ruth E. Stilwell, An Introduction to the Spaceport Industry, 2020
Janet K. Tinoco, Chunyan Yu, Diane Howard, Ruth E. Stilwell
Based on research to date, nation-states use a variety of propellants. Table 3.8 compares countries with their most prevalent propellant type, while Figures 3.16, 3.17, and 3.18 highlight the propellant of choice used by the U.S., Russia, and China, respectively. Most LVs in the U.S. today use solid propellant and LOX/kerosene. Russian rockets largely use N2O4/Unsymmetrical dimethylhydrazine (UDMH) and LOX/kerosene, while China favors N2O4/UDMH, followed by solid. This, of course, depends on the number of rocket stages and boosters needed for the mission at hand. Finally, once LV manufacturers lock into a reliable design that meets their requirements, they typically create scalable versions of the same design. Hence, SpaceX uses LOX/kerosene with its Merlin-1D rocket engines. It builds larger rockets and fulfills increased propulsion needs by adding more Merlin-1D engines. This standardization leads to increased savings in time and money.
The Apollo command and service modules
Published in Jonathan Allday, Apollo in Perspective, 2019
The service propulsion engine was just over 1 m long and its engine bell extended 2.7 m from the base of the service module and opened to a maximum diameter of 2 m. This crucial engine had to be ultra-reliable, with the fewest number of parts possible. If it did not ‘light’ at the appropriate moment, the spacecraft could not enter lunar orbit, or worse, break free of orbit to return to Earth. To ensure reliability, pumps were not used to transfer fuel and oxidiser to the thrust chamber. Instead, pressurised nitrogen from the two tanks mounted in the central core was used to force fuel and oxidiser from their storage tanks into their respective sump tanks and from there to the thrust chamber, a process that simply required valves to open. A hypergolic propellant mixture (fuel: 50% hydrazine and 50% unsymmetrical dimethylhydrazine (UDMH) oxidiser: nitrogen tetroxide) was used and 75% of the fully deployed module's mass was propellant.
Preparation and characterization of graphene oxide/O-carboxymethyl chitosan (GO/CMC) composite and its unsymmetrical dimethylhydrazine (UDMH) adsorption performance from wastewater
Published in Environmental Technology, 2023
Jun Su, Ying Jia, Ruomeng Hou, Yuanzheng Huang, Keke Shen, Zhaowen Hao
Unsymmetrical dimethylhydrazine (UDMH, (CH3)2NNH3) is a high-energy liquid rocket propellant with good performance [1]. The large amount of UDMH wastewater generated by its leakage and emergency disposal poses a major threat to the environment and humans. UDMH can lead to carcinogenic, mutagenic, convulsive, teratogenic, embryotoxic, and other adverse consequences [2]. Hence, UDMH is known as a highly dangerous toxic substance with the maximum permissible concentration in ambient water as low as 0.02 mg · L−1 [3]. Therefore, the removal of UDMH is highly significant and desirable.