Specific impulse is a measure of how efficiently a rocket or jet engine uses propellant, expressed as the thrust produced per unit weight of propellant consumed per second, conventionally given in seconds. A higher specific impulse means an engine extracts more thrust from a given mass of propellant, which is why it is the standard figure of merit for comparing propulsion systems from chemical rockets to ion thrusters. Chemical rocket engines typically achieve specific impulses in the low hundreds of seconds, while electric propulsion systems can exceed several thousand seconds at far lower thrust.
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Read the Wikipedia article for Specific impulse in full (raw MediaWiki extract, not a summary); it defines and explains the quantity at length but credits no individual and gives no date for formulating or naming it. Concept Domain Connections
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Wikimedia FoundationSpecific impulse, propulsion systems comparison sectionQuote, Specific impulse, propulsion systems comparison section
In many cases, propulsion systems with very high specific impulse-some ion thrusters reach 25-35 times better Isp than chemical engines-produce correspondingly low thrust.
Specific impulse (Wikipedia)
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Specific impulse (usually abbreviated as Isp) is a physical quantity defined as the ratio of change in momentum (impulse) to the mass used, usually fuel.
In Group: Rocket Performance and Propulsion, Lead sentence
Specific impulse (usually abbreviated as Isp) is a physical quantity defined as the ratio of change in momentum (impulse) to the mass used, usually fuel.
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