Oxidizer hydrogen is the number of hydrogen atoms in an oxidizer molecule. There are no uncombined oxygen atoms in typical fuels, so hydrogen in the oxidizer doesn't react, it only adds mass to the exhaust. Oxidizers that are high in hydrogen generally release less energy per unit mass in a reaction with an oxidizer, leading to a lower combustion temperature and a lower exhaust velocity.

The only common oxidizer with hydrogen in use is hydrogen peroxide, which decomposes into water and oxygen. It is a liquid at room temperature and can be bought in a pharmacy in low concentration, generally a three percent solution in water. Oxidizer hydrogen is used to calculate oxidizer mix hydrogen, oxidizer molecular and oxidizer oxidation.

oxidizer mix hydrogen = oxidizer mix * oxidizer hydrogen + propellant mix * propellant hydrogen

oxidizer molecular = oxidizer hydrogen + 16 * oxidizer oxygen

oxidizer oxidation = 2 * oxidizer oxygen - oxidizer hydrogen
 
 

This is used in astropolis, bipropellant rocket, tripropellant rocket, pumped rocket and rocket cost.
 
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