ABLE IV Space Engine

How it Works

The Design Challenges for the world’s first rocket engine to fire and operate in space.

Cold start in the vacuum of space.

Simplicity for reliability

Minimize engine & fuel weight

Multiple restart (previous rocket engines simply burned until their fuel was exhausted)

Variable start and duration times controlled from earth

1800°F hydrazine decomposition temperature requires suitable materials for thrust chamber and exhaust nozzle

Hydrazine decomposition requires preheating the catalyst above 500°F


Never been done before by anyone!

Why Hydrazine?

Does not require an oxidizer or igniter

Can be stored as liquid on earth at normal temperatures (freezing and boiling points similar to water)

In presence of catalyst, liquid Hydrazine breaks down into ammonia, nitrogen, and hydrogen gases.

Decomposition process is exothermic process well suited to rocket propulsion.

Combination of hydrazine and nitrogen is hypergolic (spontaneously ignites without an igniter) This combination yielded Able IV’s  “bipropellant slug starts” for preheating the catalyst.

The following information is from Glasser & Spangler,”The Able – 5 Lunar Satellite,” 1960, pg 37

http://www.sdfo.org/stl/60-00-00%20The%20Able-5%20Lunar%20Satellite.pdf

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