specific impulse

American  

noun

Rocketry.

1. a measure, usually in seconds, of the efficiency with which a rocket engine utilizes its propellants, equal to the number of pounds of thrust produced per pound of propellant burned per second.

2. the specific impulse that a given combination of propellants would produce in an ideal rocket engine providing complete combustion, no friction losses, and no lateral expansion of the exhaust.

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specific impulse British  

noun

1. the ratio of the thrust produced by a rocket engine to the rate of fuel consumption: it has units of time and is the length of time that unit weight of propellant would last if used to produce one unit of thrust continuously

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Etymology

Origin of specific impulse

First recorded in 1945–50

Example Sentences

In rocket language. the hydrogen engine produces a "specific impulse" 30% greater than its kerosene-burning rivals.

From Time Magazine Archive

Using liquid fluorine as the oxidizer instead of liquid oxygen would boost specific impulse to between 300 and 345 Ibs.

From Time Magazine Archive

Its reaction has a specific impulse of 373.

From Time Magazine Archive

The specific impulse of the traditional kerosene-oxygen combination is only 249.

From Time Magazine Archive

“It’s a means of determining the relative merits of propellants. By using the number denoting the specific impulse, calculations can be made to determine the exhaust velocity of a rocket and ultimately its overall performance.”

From "October Sky" by Homer Hickam