A thrust curve, sometimes known as a "performance curve" or "thrust profile" is a graph of the thrust of an engine or motor, (usually a rocket) with respect to time.
An engine or motor is a machine designed to convert one form of energy into mechanical energy. Heat engines burn a fuel to create heat which is then used to do work. Internal combustion engines are heat engines that burn fuel in a combustion chamber to extract work from the pressure of expanding gases. Electric motors convert electrical energy into mechanical motion; pneumatic motors use compressed air; and clockwork motors in wind-up toys use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create forces and eventually motion.
Most engines do not produce linear thrust (thrust which increases at a constant rate with time). Instead, they produce a curve of some type, where thrust will slowly rise to a peak, and then fall, or "tail off". Rocket engines, particularly solid-fuel rocket engines, produce very consistent thrust curves, making this a useful metric for judging their performance.
This information is vital when designing spacecraft, particularly multistage spacecraft, since it may be advantageous to separate the engine and its associated fuel tanks and machinery before the fuel has been fully exhausted. This is because even though the engine is still producing thrust during the tail off phase, it may be so little that the spacecraft would be more efficient without it.
A multistage rocket, or step rocket, is a launch vehicle that uses two or more rocket stages, each of which contains its own engines and propellant. A tandem or serial stage is mounted on top of another stage; a parallel stage is attached alongside another stage. The result is effectively two or more rockets stacked on top of or attached next to each other. Two-stage rockets are quite common, but rockets with as many as five separate stages have been successfully launched.
A rocket is a missile, spacecraft, aircraft or other vehicle that obtains thrust from a rocket engine. Rocket engine exhaust is formed entirely from propellant carried within the rocket before use. Rocket engines work by action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space.
A solid-propellant rocket or solid rocket is a rocket with a rocket engine that uses solid propellants (fuel/oxidizer). The earliest rockets were solid-fuel rockets powered by gunpowder; they were used in warfare by the Chinese, Indians, Mongols and Persians, as early as the 13th century.
A hybrid-propellant rocket is a rocket with a rocket motor that uses rocket propellants in two different phases: one solid and the other either gas or liquid. The hybrid rocket concept can be traced back at least 75 years.
A nuclear thermal rocket is a proposed spacecraft propulsion technology. In a nuclear thermal rocket a working fluid, usually liquid hydrogen, is heated to a high temperature in a nuclear reactor, and then expands through a rocket nozzle to create thrust. This kind of thermal rocket, the nuclear reactor's energy replaces the chemical energy of the propellant's reactive chemicals in a chemical rocket. The thermal heater / inert propellant paradigm as opposed to the reactive propellants of chemical rockets turns out to produce a superior effective exhaust velocity, and therefore a superior propulsive efficiency, with specific impulses on the order of twice that of chemical engines. The overall gross lift-off mass of a nuclear rocket is about half that of a chemical rocket, and hence when used as an upper stage it roughly doubles or triples the payload carried to orbit.
Propulsion means to push forward or drive an object forward. The term is derived from two Latin words: pro, meaning before or forward; and pellere, meaning to drive. A propulsion system consists of a source of mechanical power, and a propulsor.
JATO, is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term JATO is used interchangeably with the term RATO, for rocket-assisted take-off.
A rocket engine uses stored rocket propellant mass for forming its high-speed propulsive jet. Rocket engines are reaction engines, obtaining thrust in accordance with Newton's third law. Most rocket engines use combustion, although non-combusting forms also exist. Vehicles propelled by rocket engines are commonly called rockets. Since they need no external material to form their jet, rocket engines can perform in a vacuum and thus can be used to propel spacecraft and ballistic missiles.
A propellant or propellent is a chemical substance used in the production of energy or pressurized gas that is subsequently used to create movement of a fluid or to generate propulsion of a vehicle, projectile, or other object. Common propellants are energetic materials and consist of a fuel like gasoline, jet fuel, rocket fuel, and an oxidizer. Propellants are burned or otherwise decomposed to produce the propellant gas. Other propellants are simply liquids that can readily be vaporized.
The Space Shuttle Solid Rocket Boosters (SRBs) were the first solid fuel motors to be used for primary propulsion on a vehicle used for human spaceflight and provided the majority of the Space Shuttle's thrust during the first two minutes of flight. After burnout, they were jettisoned and parachuted into the Atlantic Ocean where they were recovered, examined, refurbished, and reused.
Solid-fuel rocket boosters (SRBs) are large solid propellant motors used to provide thrust in spacecraft launches from initial launch through the first ascent stage. Many launch vehicles, including the Ariane 5, GSLV MK3, Atlas V, and the NASA Space Shuttle, have used SRBs to give launch vehicles much of the thrust required to ascend from the launch pad. The Space Shuttle Solid Rocket Boosters were the largest solid propellant motors ever built and designed for recovery and reuse.
Little Joe II was an American rocket used from 1963–1966 for five unmanned tests of the Apollo spacecraft launch escape system (LES), and to verify the performance of the command module parachute recovery system in abort mode. It was named after a similar rocket designed for the same function in Project Mercury. Launched from White Sands Missile Range in New Mexico, it was the smallest of four launch rockets used in the Apollo program.
Estes Industries is a model rocket company that was started in Denver, Colorado, USA. The company was the first to mass-produce model rocket engines with consistent and reliable performance.
Aerojet's M-1 was the largest and most powerful liquid-hydrogen-fueled liquid-fuel rocket engine to be designed and component-tested. The M-1 offered a baseline thrust of 6.67 MN and 8 MN as its immediate growth target. If built, the M-1 would be larger and more efficient than the famed F-1 that powered the first stage of the Saturn V rocket to the Moon.
Ammonium perchlorate composite propellant (APCP) is a modern solid-propellant rocket used in rocket vehicles. It differs from many traditional solid rocket propellants such as black powder or zinc-sulfur, not only in chemical composition and overall performance, but also by the nature of how it is processed. APCP is cast into shape, as opposed to powder pressing as with black powder. This provides manufacturing regularity and repeatability, which are necessary requirements for use in the aerospace industry.
Rocket propellant is a material used either directly by a rocket as the reaction mass, or indirectly to produce the reaction mass in a chemical reaction. The reaction mass is that which is ejected, typically with very high speed, from a rocket engine to produce thrust.
The Star is a family of American solid-fuel rocket motors used by many space propulsion and launch vehicle stages. It is used almost exclusively as an upper stage.
Tom Mueller is an American rocket engineer and rocket engine designer. He is a founding employee of SpaceX, a space transport services company headquartered in Hawthorne, California.
The Algol family of solid-fuel rocket stages and boosters built by Aerojet and used on a variety of launch vehicles. It was developed by Aerojet from the earlier Jupiter Senior and the Navy Polaris programs. Upgrades to the Algol motor occurred from 1960 till the retirement of the Scout launch vehicle in 1994.
A liquid apogee engine (LAE), or apogee engine, refers to a type of chemical rocket engine typically used as the main engine in a spacecraft.
AJ-60A is a solid rocket booster produced by Aerojet Rocketdyne. They are currently used as strap-on boosters on United Launch Alliance's Atlas V rocket.