UH 25 is a fuel mixture for rockets. It was developed for the European
Ariane 2–4 launch vehicles.
UH 25 was developed after a disaster during flight 2 of the Ariane 1 rocket. During launch, one of the four
Viking
Vikings ; non, víkingr is the modern name given to seafaring people originally from Scandinavia (present-day Denmark, Norway and Sweden),
who from the late 8th to the late 11th centuries raided, pirated, traded and se ...
engines on the first stage developed a combustion instability which led to an engine fire, subsequent explosion and destruction of the vehicle. Following this event and starting with Ariane 2, the fuel was changed from pure UDMH to the mixture UH 25.
UH 25 was used in Ariane rocket versions 2 through 4, and in the Indian
GSLV Mk III
The Launch Vehicle Mark-3 (LVM 3), previously referred to as the Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk3), is a three-stage medium-lift launch vehicle developed by the Indian Space Research Organisation (ISRO). Primarily desi ...
UH 25 is a mixture of 75%
UDMH and 25%
hydrazine hydrate.
[Tim Furniss: ''Ingenieure bei der Arbeit, Raumschiffe und Raketen'', Tessloff Verlag, Nürnberg (1989), Seite: 31 (German)] It is
hypergolic
A hypergolic propellant is a rocket propellant combination used in a rocket engine, whose components spontaneously ignite when they come into contact with each other.
The two propellant components usually consist of a fuel and an oxidizer. T ...
with
dinitrogen tetroxide
Dinitrogen tetroxide, commonly referred to as nitrogen tetroxide (NTO), and occasionally (usually among ex-USSR/Russia rocket engineers) as amyl, is the chemical compound N2O4. It is a useful reagent in chemical synthesis. It forms an equilibrium ...
as oxidizer, and both can be stored as liquids at room temperature.
Danger
Like its components, UH 25 is flammable, toxic (carcinogenic) and corrosive.
Safety labels
See also
*
Aerozine 50 - a 50:50 mix of hydrazine and UDMH.
*''
C-Stoff
C-Stoff (; "substance C") was a reductant used in bipropellant rocket fuels (as a fuel itself) developed by Hellmuth Walter Kommanditgesellschaft in Germany during World War II. It was developed for use with T-Stoff (a high-test peroxide) as an o ...
'', the 50:50 mix of hydrazine and methanol fuel used for the
HWK 109-509 Nazi rocket motor series.
References
This Article has been based on a translation of the Article UH 25 from the German-speaking Wikipedia in the Version from February 9, 2006 13:01 CET. A List of the main Authors (History) in accordance with GNU FDL
The GNU Free Documentation License (GNU FDL or simply GFDL) is a copyleft license for free documentation, designed by the Free Software Foundation (FSF) for the GNU Project. It is similar to the GNU General Public License, giving readers the r ...
i
here
Rocket fuels
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