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The specific impulse of a rocket can be defined in terms of thrust per unit mass flow of propellant. This is an equally valid (and in some ways somewhat simpler) way of defining the effectiveness of a rocket propellant. For a rocket, the specific impulse defined in this way is simply the effective exhaust velocity relative to the rocket, v e ...
The highest-specific-impulse chemistry ever test-fired in a rocket engine was lithium and fluorine, with hydrogen added to improve the exhaust thermodynamics (all propellants had to be kept in their own tanks, making this a tripropellant). The combination delivered 542 s specific impulse in vacuum, equivalent to an exhaust velocity of 5320 m/s.
The primary specific impulse advantage of liquid propellants is due to the availability of high-performance oxidizers. Several practical liquid oxidizers ( liquid oxygen , dinitrogen tetroxide , and hydrogen peroxide ) are available which have better specific impulse than the ammonium perchlorate used in most solid rockets when paired with ...
A liquid-propellant rocket or liquid rocket uses a rocket engine burning liquid propellants. (Alternate approaches use gaseous or solid propellants.) Liquids are desirable propellants because they have reasonably high density and their combustion products have high specific impulse (I sp). This allows the volume of the propellant tanks to be ...
Ammonium perchlorate composite propellant is typically for aerospace rocket propulsion where simplicity and reliability are desired and specific impulses (depending on the composition and operating pressure) of 180–260 s (1.8–2.5 km/s) are adequate.
A tripropellant rocket is a rocket that uses three propellants, as opposed to the more common bipropellant rocket or monopropellant rocket designs, which use two or one propellants, respectively. Tripropellant systems can be designed to have high specific impulse and have been investigated for single-stage-to-orbit designs.
A hypergolic propellant is a rocket propellant combination used in a rocket engine, ... (ClF 5) presents the same hazards, but offers higher specific impulse than ClF 3.
The higher the specific impulse, the less propellant is required to provide the desired impulse. The specific impulse that can be achieved is primarily a function of the propellant mix (and ultimately would limit the specific impulse), but practical limits on chamber pressures and the nozzle expansion ratios reduce the performance that can be ...