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

"A new concept for in-space propulsion is proposed in which propellant is not ejected from the engine, but instead is captured to create a nearly infinite specific impulse," Burns wrote in the paper's abstract.

From Fox News

Cold gas thrusters can get to a specific impulse of about 70 seconds.

From The Verge

Cold gas thrusters have a relatively low specific impulse, which means they need a lot more fuel — or air, in this case — to get a decent amount of thrust.

From The Verge

The efficiency of rockets are generally measured by their specific impulse, which is the ratio of how much thrust a rocket produces to the weight flow of its fuel.

From Forbes

Traditional chemical rockets have a specific impulse of 460s, which is why they rely on multiple stages to reach orbit – one rocket engine firing isn’t enough.

From Forbes