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 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.[1]
UH 25 was used in Ariane rocket versions 2 through 4, and in the Indian GSLV Mk III.
UH 25 is a mixture of 75% UDMH and 25% hydrazine hydrate.[2] It is hypergolic with dinitrogen tetroxide as oxidizer, and both can be stored as liquids at room temperature.
^Die Geschichte der Europarakete Ariane (German)
^Tim Furniss: Ingenieure bei der Arbeit, Raumschiffe und Raketen, Tessloff Verlag, Nürnberg (1989), ISBN 3-7886-0493-X Seite: 31 (German)
UH25 is a fuel mixture for rockets. It was developed for the European Ariane 2–4 launch vehicles. UH25 was developed after a disaster during flight 2...
the original on 2012-10-29. Retrieved 2013-02-02. "Piasecki PV-18 (HUP/H-25/UH-25) (Photo)". pictaero.com. Retrieved 2 February 2013. Skaarup, Howard (2009)...
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them to France for the Ariane 1 first and second stages (replaced with UH25); ISRO rockets using Vikas engine. Less-common or obsolete hypergolic propellants...
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000 lbf) Specific impulse 2,376 N‑s/kg (242.3 s) Burn time 138 s Propellant UH25 / N2O4 Second stage – L-33 Height 11.47 m (37.6 ft) Diameter 2.60 m (8 ft...
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