Red fuming nitric acid
) is a storable oxidizer
used as a rocket propellant
. It consists mainly of nitric acid
), also containing 13% dinitrogen tetroxide
and 3% water
. The color
of the resulting red fuming nitric acid is due to the dinitrogen tetroxide, which breaks down partially to form nitrogen dioxide
. White fuming nitric acid
does not contain free dinitrogen tetroxide.
It is usually used with an inhibitor (with various, sometimes secret, substances, including hydrogen fluoride; any such combination is called IRFNA) because nitric acid attacks most container materials.
It can also be a monopropellant; with substances like ammonium nitrates dissolved in it, it can be used as the sole fuel in a rocket. It is not normally used this way however.
During World War II, the German military used RFNA in some rockets. The mixtures used were called S-Stoff (96% nitric acid with 4% ferric chloride) and SV-Stoff (94% nitric acid with 6% dinitrogen tetroxide).
Inhibited RFNA, used in modified SS-1 Scud missiles as an oxidizer by the Iraqi military during the 1991 Persian Gulf War, was suggested as a possible factor causing Gulf War Syndrome. However, this theory was later refuted.
- IRFNA IIIa: 83.4% HNO3, 14% NO2, 2% H2O, 0.6% HF
- IRFNA IV HDA: 54.3% HNO3, 44% NO2, 1% H2O, 0.7% HF
- S-Stoff: 96% HNO3, 4% FeCl3
- SV-Stoff: 94% HNO3, 6% N2O4
- AK20: 80% HNO3, 20% N2O4
- AK20F: 80% HNO3, 20% N2O4, fluorine-based inhibitor
- AK20I: 80% HNO3, 20% N2O4, iodine-based inhibitor
- AK20K: 80% HNO3, 20% N2O4, unknown inhibitor
- AK27I: 73% HNO3, 27% N2O4, iodine-based inhibitor
- AK27P: 73% HNO3, 27% N2O4, unknown inhibitor