specific impulse


Definition of specific impulse 

: the thrust produced per unit rate of consumption of the propellant that is usually expressed in pounds of thrust per pound of propellant used per second and that is a measure of the efficiency of a rocket engine

Examples of specific impulse in a Sentence

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Never used before in a larger engine, propylene has useful properties of higher density and specific impulse that will give Vector's small rocket more performance. Eric Berger, Ars Technica, "Rocket Report: SpaceX gets Moon launches, South Korean rocket, BE-4 wins," 28 Sep. 2018 Cold gas thrusters can get to a specific impulse of about 70 seconds. Loren Grush, The Verge, "Here’s how Elon Musk might use rocket thrusters on the new Tesla Roadster," 16 June 2018 This measures the thrust generated by any given amount of fuel, and liquid engines have a higher specific impulse than solids, which explains a great deal of their attraction. Joe Pappalardo, Popular Mechanics, "The Rocket Fuel Rivalry Shaping the Future of Spaceflight," 10 Apr. 2018 An electric propulsion engine—such as a Hall thruster that ionizes xenon gas—has a high specific impulse, as much as 10 times that of NTP. Jay Bennett, Popular Mechanics, "NASA's Nuclear Thermal Engine Is a Blast From the Cold War Past," 21 Feb. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'specific impulse.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of specific impulse

1947, in the meaning defined above

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Last Updated

7 Dec 2018

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The first known use of specific impulse was in 1947

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