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Dual-thrust
In a dual-thrust solid propellant rocket engine, the propellant mass is composed of two different types (densities) of fuel. In the case of a tandem dual-thrust motor, the fuel nearest to the rocket nozzle burns fast, and the fuel further into the motor's body burns slower. This gives the rocket higher thrust initially, accelerating it rapidly to high speed. When all the fast-burning propellant has burnt, the slow-burning propellant delivers a lower level of thrust. The first phase of acceleration is called "boost" and the second phase "sustain". Not all dual-thrust motors are in a tandem arrangement but non-tandem motors function much the same; they just have a different physical layout of fuel. For example, they might burn from the inside to the outside (core burning), rather than from the end in (end burning). The advantage of dual-thrust motors is that, if the fuel were all of the fast-burning kind, the rocket would accelerate up to a higher speed initially but because air res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid Propellant Rocket
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 Arabs, Chinese, Persians, Mongols, and Indians as early as the 13th century. All rockets used some form of solid or powdered propellant up until the 20th century, when liquid-propellant rockets offered more efficient and controllable alternatives. Solid rockets are still used today in military armaments worldwide, model rockets, solid rocket boosters and on larger applications for their simplicity and reliability. Since solid-fuel rockets can remain in storage for an extended period without much propellant degradation and because they almost always launch reliably, they have been frequently used in military applications such as missiles. The lower performance of solid propellants (as compared to liquids) does not favor their use as primary propulsion in modern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rocket Engine
A rocket engine uses stored rocket propellants as the reaction mass for forming a high-speed propulsive jet of fluid, usually high-temperature gas. Rocket engines are reaction engines, producing thrust by ejecting mass rearward, in accordance with Newton's third law. Most rocket engines use the combustion of reactive chemicals to supply the necessary energy, but non-combusting forms such as cold gas thrusters and nuclear thermal rockets also exist. Vehicles propelled by rocket engines are commonly called rockets. Rocket vehicles carry their own oxidiser, unlike most combustion engines, so rocket engines can be used in a vacuum to propel spacecraft and ballistic missiles. Compared to other types of jet engine, rocket engines are the lightest and have the highest thrust, but are the least propellant-efficient (they have the lowest specific impulse). The ideal exhaust is hydrogen, the lightest of all elements, but chemical rockets produce a mix of heavier species, reducing the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tandem
Tandem, or in tandem, is an arrangement in which a team of machines, animals or people are lined up one behind another, all facing in the same direction. The original use of the term in English was in ''tandem harness'', which is used for two or more draft horses, or other draft animals, harnessed in a single line one behind another, as opposed to a pair, harnessed side by side, or a team of several pairs. The tandem harness allows additional animals to provide pulling power for a vehicle designed for a single animal. The English word ''tandem'' derives from the Latin adverb , meaning ''at length'' or ''finally''. It is a word play, using the Latin phrase (referring to time, not position) for English "at length, lengthwise". Tandem bicycles are named for their tandem seating, a more common arrangement than side-by-side "sociable" seating. ''Tandem'' can also be used more generally to refer to any group of persons or objects working together, not necessarily in line. Automob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Resistance
In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or between a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, the drag force depends on velocity. Drag force is proportional to the velocity for low-speed flow and the squared velocity for high speed flow, where the distinction between low and high speed is measured by the Reynolds number. Even though the ultimate cause of drag is viscous friction, turbulent drag is independent of viscosity. Drag forces always tend to decrease fluid velocity relative to the solid object in the fluid's path. Examples Examples of drag include the component of the net aerodynamic or hydrodynamic force acting opposite to the dire ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multistage Rocket
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. By jettisoning stages when they run out of propellant, the mass of the remaining rocket is decreased. Each successive stage can also be optimized for its specific operating conditions, such as decreased atmospheric pressure at higher altitudes. This ''staging'' allows the thrust of the remaining stages to more easily accelerate the rocket to its final speed and height. In serial or tandem staging schemes, the first stage is at the bottom and is usually the largest, the second stage and subseq ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
