Information about Thrust
Thrust is a reaction force described quantitatively by Newton's Second and Third Laws. When a system expels or accelerates mass in one direction the accelerated mass will cause a proportional but opposite force on that system.
A fixed-wing aircraft generates forward thrust when a spinning propeller moves air, or gases are ejected from a jet engine (or rocket engine), opposite the direction of flight. The forward thrust is proportional to the (mass of the air) multiplied by (average velocity of the airstream). Reverse thrust can be generated to aid braking after landing by reversing the pitch of variable pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, and vector some of this thrust fore and aft to control forward speed.
A motorboat generates thrust (or reverse thrust) when the propellers are turned to accelerate water backwards (or forwards). The resulting thrust pushes the boat in the equal and opposite direction to the sum of the momentum change in the water flowing through the propeller.
A rocket's mass is propelled forward by a thrust force equal to, and opposite of, the time-rate of momentum change of the exhaust mass accelerated from the combustion chamber through the rocket engine nozzle. This is the exhaust velocity with respect to the rocket, times the time-rate at which the mass is expelled, or in mathematical terms:
where:
Of course, for a launch the thrust at lift-off should be more than the weight, and with a fair margin, because a "slow launch" would be very inefficient.
Each of the three Space shuttle main engines can produce a thrust of 1.8 MN, and each of its two Solid Rocket Boosters 14.7 MN, together 34.8 MN. Compare with the mass at lift-off of 2,040,000 kg, hence a weight of 20 MN.
By contrast, the simplified Aid for EVA Rescue (SAFER) has 24 thrusters of 3.56 N each.
In the air breathing category, the AMT-USA AT-180 jet engine developed for radio-controlled aircraft produce 90 N (20 Lbf) of thrust.[1] The GE90-115B engines fitted on the Boeing 777-300ER, recognized by the Guinness Book of World Records as the "World's Most Powerful Commercial Jet Engine," have a tested thrust of 569 kN (127,900 lbf).
Examples
)
Forces on an aircraft
A fixed-wing aircraft generates forward thrust when a spinning propeller moves air, or gases are ejected from a jet engine (or rocket engine), opposite the direction of flight. The forward thrust is proportional to the (mass of the air) multiplied by (average velocity of the airstream). Reverse thrust can be generated to aid braking after landing by reversing the pitch of variable pitch propeller blades, or using a thrust reverser on a jet engine. Rotary wing aircraft and thrust vectoring V/STOL aircraft use engine thrust to support the weight of the aircraft, and vector some of this thrust fore and aft to control forward speed.
A motorboat generates thrust (or reverse thrust) when the propellers are turned to accelerate water backwards (or forwards). The resulting thrust pushes the boat in the equal and opposite direction to the sum of the momentum change in the water flowing through the propeller.
A rocket's mass is propelled forward by a thrust force equal to, and opposite of, the time-rate of momentum change of the exhaust mass accelerated from the combustion chamber through the rocket engine nozzle. This is the exhaust velocity with respect to the rocket, times the time-rate at which the mass is expelled, or in mathematical terms:
where:
- T = thrust generated (force),
rate of change of mass with respect to time (fuel burn rate).
- v = exhaust velocity.
Of course, for a launch the thrust at lift-off should be more than the weight, and with a fair margin, because a "slow launch" would be very inefficient.
Each of the three Space shuttle main engines can produce a thrust of 1.8 MN, and each of its two Solid Rocket Boosters 14.7 MN, together 34.8 MN. Compare with the mass at lift-off of 2,040,000 kg, hence a weight of 20 MN.
By contrast, the simplified Aid for EVA Rescue (SAFER) has 24 thrusters of 3.56 N each.
In the air breathing category, the AMT-USA AT-180 jet engine developed for radio-controlled aircraft produce 90 N (20 Lbf) of thrust.[1] The GE90-115B engines fitted on the Boeing 777-300ER, recognized by the Guinness Book of World Records as the "World's Most Powerful Commercial Jet Engine," have a tested thrust of 569 kN (127,900 lbf).
References
See also
- Gimballed thrust, the most common thrust system in modern rockets
- Thrust-to-weight ratio
- Thrust vectoring
Action and the other the Reaction (actio et reactio in Latin). Both forces are equal in magnitude and opposite in direction. The distinction between action and reaction is purely arbitrary: anyone of the two forces can be considered an action, in which case the
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In physics, force is an action or agency that causes a body of mass m to accelerate. It may be experienced as a lift, a push, or a pull. The acceleration of the body is proportional to the vector sum of all forces acting on it (known as net force or resultant force).
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Sir Isaac Newton
Isaac Newton at 46 in
Godfrey Kneller's 1689 portrait
Born 4 January 1643 [OS: 25 December 1642]
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Isaac Newton at 46 in
Godfrey Kneller's 1689 portrait
Born 4 January 1643 [OS: 25 December 1642]
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Newton's laws of motion are three physical laws which provide relationships between the forces acting on a body and the motion of the body, first compiled by Sir Isaac Newton.
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acceleration is defined as the rate of change of velocity, or, equivalently, as the second derivative of position. It is thus a vector quantity with dimension length/time². In SI units, acceleration is measured in metres/second² (m·s-²).
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Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic
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fixed-wing aircraft is a heavier-than-air craft where movement of the wings in relation to the aircraft is not used to generate lift. The term is used to distinguish from rotary-wing aircraft, or ornithopters, where the movement of the wing surfaces relative to the aircraft
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propeller is essentially a type of fan which transmits power by converting rotational motion into thrust for propulsion of a vehicle such as an aircraft, ship, or submarine through a fluid such as water or air, by rotating two or more twisted blades about a central shaft, in a
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jet engine is an engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's . This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets, but in common usage, the term generally refers to a
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rocket engine is a reaction engine that takes all its reaction mass from within tankage and forms it into a high speed jet, thereby obtaining thrust in accordance with Newton's third law.
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Mass is a fundamental concept in physics, roughly corresponding to the intuitive idea of "how much matter there is in an object". Mass is a central concept of classical mechanics and related subjects, and there are several definitions of mass within the framework of relativistic
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velocity is defined as the rate of change of position. It is a vector physical quantity, both speed and direction are required to define it. In the SI (metric) system, it is measured in meters per second (m/s). The scalar absolute value (magnitude) of velocity is speed.
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Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's output so that the thrust produced is directed forward, rather than aft. This acts against the forward travel of the aircraft, providing deceleration.
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Rotorcraft is a category of heavier-than-air flying machines that use lift generated by wings that revolve around a mast called rotor blades. Several rotor blades mounted to a single mast is referred to as a rotor.
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Thrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine(s) in a direction other than parallel to the vehicle's longitudinal axis.
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motorboat is a vessel propelled by an internal combustion engine driving a jet or a propeller. The International Regulations for Preventing Collisions at Sea defines a "power driven vessel" as any vessel propelled by machinery
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momentum (pl. momenta; SI unit kg m/s, or, equivalently, N•s) is the product of the mass and velocity of an object. For more accurate measures of momentum, see the section "modern definitions of momentum" on this page.
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rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving fluid from within a rocket engine.
The history of rockets goes back to at least the 13th century[1].
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The history of rockets goes back to at least the 13th century[1].
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Space Shuttle Main Engines (SSMEs) are the three main engines on the Space Shuttle orbiter. They are constructed by Pratt & Whitney's Rocketdyne Division. The SSME is also designated as the RS-24 for engineering purposes.
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The newton (symbol: N) is the SI derived unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics.
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The Space Shuttle Solid Rocket Booster (SRB) is the rocket that provides 83% of liftoff thrust for the Space Shuttle. It is the largest solid rocket ever flown. Each SRB produces 1.8 times the liftoff thrust of the F-1 engine used in the Saturn V moon rocket.
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Simplified Aid for EVA Rescue (SAFER) is a small, self-contained, propulsive backpack system used to provide free-flying mobility for a Space Shuttle or International Space Station (ISS) crewmember during extra-vehicular activity (EVA).
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Radio-controlled aircraft (abbreviated RC aircraft or RC plane) is a model aircraft that is controlled remotely via radio control. It is typically controlled with a hand-held transmitter and a receiver within the craft.
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Type Airliner
Manufacturer Boeing Commercial Airplanes
Maiden flight 1994-06-12
Introduction 1995-06-07 with United Airlines
Primary users Singapore Airlines
Air France-KLM
Emirates
United Airlines
Produced
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Manufacturer Boeing Commercial Airplanes
Maiden flight 1994-06-12
Introduction 1995-06-07 with United Airlines
Primary users Singapore Airlines
Air France-KLM
Emirates
United Airlines
Produced
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Guinness World Records, known until 2000 as The Guinness Book of Records (and in previous U.S. editions The Guinness Book of World Records
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Gimballed thrust is the system of thrust vectoring used in most modern rockets, including the Space Shuttle and the Saturn V lunar rockets.
In a gimballed thrust system, the exhaust nozzle of the rocket can be swiveled from side to side.
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In a gimballed thrust system, the exhaust nozzle of the rocket can be swiveled from side to side.
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Thrust-to-weight ratio is, as its name suggests, the ratio of instantaneous thrust to weight (where weight means weight at the Earth’s surface). It is a dimensionless parameter characteristic of rockets and jet engines, and of vehicles propelled by such engines (typically
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Thrust vectoring is the ability of an aircraft or other vehicle to direct the thrust from its main engine(s) in a direction other than parallel to the vehicle's longitudinal axis.
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