UH 25

from Wikipedia, the free encyclopedia
UH 25
Brief description Rocket fuel
Characteristic components

75% 1,1-dimethylhydrazine and 25% hydrazine hydrate

properties
Physical state liquid
Hypergol with

Dinitrogen tetroxide , nitric acid , MON

safety instructions
GHS labeling of hazardous substances
02 - Highly / extremely flammable 05 - Corrosive 06 - Toxic or very toxic
08 - Dangerous to health 09 - Dangerous for the environment

danger

H and P phrases H: 225-226-301-310-330-350-314-317-410
P: 301 + 310-303 + 361 + 353-305 + 351 + 338-320-361-405-501
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Components
Structure of 1,1-dimethylhydrazine
Structure of hydrazine
1,1-Dimethylhydrazine (UDMH, above)
and hydrazine (below), the two
components of UH 25

UH 25 is a rocket fuel mixture developed for the Ariane 2 to 4 launch vehicles .

After combustion instabilities had occurred during the second flight in a Viking engine of the first stage of an Ariane 1 , which ultimately led to the engine fire and the missile launch incorrectly, it was decided to change the fuel. However, the change did not take place until the reinforced versions Ariane 2 and Ariane 3 , with the change from pure UDMH to the fuel mixture UH 25. This is how they wanted to prevent such accidents in the future.

The mixture was used in Ariane 2 to 4 and still today in the Indian PSLV and GSLV missiles . These use Viking engines manufactured under license in India .

UH 25 is a mixture of 75% UDMH and 25% hydrazine hydrate . Together with the oxidizing agent nitrogen tetroxide , it forms a hypergolic , toxic and corrosive fuel mixture that can be stored at normal temperatures . Aerozin 50 consists of similar components .

hazards

Like its constituents hydrazine and UDMH, UH 25 is toxic, corrosive and carcinogenic.

Individual evidence

  1. ↑ a b Entry on 1,1-dimethylhydrazine in the GESTIS substance database of the IFA , accessed on April 28, 2008(JavaScript required) .
  2. ↑ a b Entry on hydrazine in the GESTIS substance database of the IFA , accessed on April 28, 2008(JavaScript required) .
  3. ↑ The history of the European Ariane rocket. Accessed: February 25, 2011
  4. ↑ Tim Furniss: Engineers at work, spaceships and rockets , Tessloff Verlag, Nuremberg (1989), ISBN 3-7886-0493-X page: 31