Hypergolic fuel
From Free net encyclopedia
Hypergolic rocket fuels spontaneously ignite when their two components come into contact with each other. While the fuel is difficult to handle, the hypergolic engine is easy to control and very reliable.
The engine can be precisely controlled with only two valves, one for each fuel component. This simplifies the control system and eliminates points of failure. With no complex starting procedure the thrust is predictable i.e. the direction and velocity of the rocket will closely match calculations.
Hypergolic fuels have been used for intercontinental ballistic missiles, especially the Titan II missile, but because of difficulties in storing fuel, the trend in ICBMs has been to move toward solid fuel boosters.
They are less likely to explode when starting. This is called a "hard start."
Some common hypergolic fuel combinations are:
- Hydrazine-nitric acid (toxic but stable)
- Aniline-nitric acid (unstable, explosive)
- Hydrogen peroxide-aniline (dust-sensitive, explosive)
- UDMH-nitrogen tetroxide (by far the most common hypergolic fuel, less reactive than others, but by no means inert)
- MMH-nitrogen tetroxide used in the end stage of the European Ariane 5 rocket
- T-Stoff and C-Stoff used in the Messerschmitt Me 163 rocket fighter plane
- Hydrazine and nitrogen tetroxideda:Hypergolisk