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Encyclopedia > Solid rocket
The Space Shuttle is initially launched with the help of solid-fuel boosters
The Space Shuttle is initially launched with the help of solid-fuel boosters

A Solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer). The earliest rockets were solid fuelled, powered by gunpowder, used by the Chinese in warfare as early as the 13th century. All rockets used some form of solid or powdered propellant up until the 20th century, when liquid rockets and hybrid rockets offered more efficient and controllable alternatives. Solid rockets are still used for their simplicity and reliability. Image File history File links Download high resolution version (700x813, 126 KB)Launching of the NASA Space Shuttle Columbia on STS-1 in April 1981. ... Image File history File links Download high resolution version (700x813, 126 KB)Launching of the NASA Space Shuttle Columbia on STS-1 in April 1981. ... The Space Shuttle Columbia seconds after engine ignition, 1981 (NASA). ... A Redstone rocket, part of the Mercury program The traditional definition of a rocket is a vehicle, missile or aircraft which obtains thrust by the reaction to the ejection of fast moving exhaust gas from within a rocket engine. ... Rocket fuel is a propellant that reacts with an oxidizing agent to produce thrust in a rocket. ... Fuel is a material with one type of energy which can be transformed into another usable energy. ... An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... Smokeless powder Gunpowder, whether black powder or smokeless powder, is a substance that burns very rapidly, releasing gases that act as a propellant in firearms. ... A propellant is a material that is used to move an object by applying a motive force. ... (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999 in the... A liquid rocket engine has fuel and oxidizer in liquid form, as opposed to a solid rocket or hybrid rocket. ... A hybrid rocket propulsion system is a rocket engine composed of a solid propellant lining a combustion chamber into which a liquid or gaseous propellant is injected so as to undergo a strong exothermic reaction to produce hot gas that is emitted through a De Laval nozzle for propulsive purposes. ...

Contents


Basic Concepts

Solid Rocket Motor
Solid Rocket Motor

A simple solid rocket motor consists of a casing, nozzle, grain (propellant charge), and igniter. Image File history File links SolidRocketMotor. ... Image File history File links SolidRocketMotor. ... Diagram of a de Laval nozzle, showing approximate flow velocity increasing from green to red A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube that is pinched in the middle, making an hourglass-shape. ...


The grain behaves like a solid mass, burning in a predictable fashion and producing exhaust gases. The nozzle dimensions are calculated to maintain a design chamber pressure, while producing thrust from the exhaust gases.


Once ignited, a simple solid rocket motor cannot be shut off, because it contains all the ingredients necessary for combustion within the chamber that they are burned in. More advanced solid rocket motors, like controllable solid motor, can not only be throttled but can be extinguished and then re-ignited by effective use of the nozzle throat area control.


Modern designs may also include; steerable nozzle for guidance, avionics, recovery hardware (parachutes), self destruct mechanisms, APU's, controllable tactical motors, controllable divert and attitude control motors and thermal management materials.
An Auxiliary Power Unit (APU) is a relatively small self-contained generator used in aircraft to start the main engines, usually with compressed air, and to provide electrical power and air conditioning while the aircraft is on the ground. ...


Design

Design begins with the total impulse required, this determines the fuel/oxidizer mass. Grain geometry and chemistry are then chosen to satisfy the required motor characteristics. t is the time duratio specific impulse [ ...


The following are chosen or solved simultaneously. The results are exact dimensions for grain, nozzle and case geometries;

  • The grain burns at a predictable rate, given its surface area and chamber pressure.
  • The chamber pressure is determined by the nozzle orifice diameter and grain burn rate.
  • Allowable chamber pressure is a function of casing design.
  • The length of burn time is determined by the grain 'web thickness'.

The grain may be bonded to the casing, or not. Case bonded motors are much more difficult to design, since deformation of both the case and grain, under operating conditions, must be compatible.


Common modes of failure in solid rocket motors include fracture of the grain, failure of case bonding, and air pockets in the grain. All of these produce an instantaneous increase in burn surface area and a corresponding increase in exhaust gas and pressure, which may potentially induce rupture of the casing.


Another failure mode is casing seal design. Seals are required in casings that have to be opened to load the grain. Once a seal fails, hot gas will erode the escape path and result in failure. This was the cause of the Space Shuttle Challenger disaster. Compression seal example A mechanical seal is a device which helps join systems or mechanisms together by preventing leakage (eg. ... The launch of the Space Shuttle Challenger on mission 51L/STS-33, the 25th of the STS (Space Transportation System) program, began at an estimated time of 16:38:00. ...


Grain

Solid fuel grains are usually molded from a thermoset elastomer, fuel, oxidizer and catalyst. HTPB and PBAN are typical elastomers which double as fuel. Ammonium perchlorate is the most common oxidizer. An oxidizing agent is a substance that oxidizes another substance in electrochemistry or redox chemical reactions in general. ... In chemistry, a catalyst (Greek: καταλύτης, catalytēs) is a substance that accelerates the rate (speed) or ease of a chemical reaction (see also catalysis) without itself being changed at the end of the chemical reaction. ... Hydroxyl-terminated polybutadiene (HTPB) is a polymer of butadiene terminated at each end with a hydroxyl functional group. ... PBAN - Polybutadiene Acrylonitrile copolymer. ... Ammonium perchlorate is a chemical compound with the formula NH4ClO4. ...


The hydrochloric acid and the aluminium oxide have negative effect on the environment. Furthermore, for military use, the smoke trail and the infrared radiation from the hot particles make it possible to detect the launch from space. These problems lead to the research in smoke less grain which contains nitrogen-containing organic molecules. The chemical compound hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. ... Flash point Non-flammable. ... Image of a small dog taken in mid-infrared (thermal) light (false color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than visible light, but shorter than microwave radiation. ...


The grain is cast in different forms for different purposes. Slow, long burning rockets have a cylinder shaped grain, burning from one end to the other. Most grains, however, are cast with a hollow core, burning from the inside out (and outside in, if not case bonded), as well as from the ends.


The thrust profile over time can be controlled by grain geometry. For example, a star shaped core will have greater initial thrust because of the additional surface area. As the star points are burned up, the surface area and thrust are reduced.


Casing

The casing may be constructed from a range of materials. Cardboard is used for model engines. Steel is used for the space shuttle boosters. Filament wound graphite epoxy casings are used for high performance motors. Use of steel requires a federal permit when building models. Categories: Rockets and missiles | Physics stubs ... The Graphite-Epoxy motor is a type of rocket engine used as a booster in the Delta II rocket, among others. ...


Nozzle

A Convergent Divergent design accelerates the exhaust gas out of the nozzle to produce thrust. Diagram of a de Laval nozzle, showing approximate flow velocity increasing from green to red A de Laval nozzle (or convergent-divergent nozzle, CD nozzle or con-di nozzle) is a tube that is pinched in the middle, making an hourglass-shape. ...


Sophisticated solid rocket motors use steerable nozzles for rocket control.


Performance

Solid fuel rocket motors have a typical specific impulse of 285 seconds (2.6 kN·s/kg). This compares to ~330 seconds (3.2 kN·s/kg) for kerosene/Lox and ~450 seconds (4.4 kN·s/kg) for liquid hydrogen/Lox bipropellant engines 1. The specific impulse (commonly abbreviated Isp) of a propulsion system is the impulse (change in momentum) per unit of propellant. ... Russian kerosene lamp Kerosene or paraffin oil (British English, not to be confused with the waxy solid also called paraffin) is a colorless flammable hydrocarbon liquid. ... Liquid oxygen (also LOx, LOX or Lox in the aerospace industry) is the liquid form of oxygen. ... LH2 is an acronym used in the aerospace industry, which stands for Liquid Hydrogen. ...


Solid rockets have a long history as the final boost stage for satellites. This is related to their simplicity, reliability, compactness and reasonably high mass fraction.[1] In aerospace engineering, the mass fraction is an important measure of a rockets efficiency. ...


Solids can also provide high thrust for relatively low cost. For this reason, solids have been used as initial stages in rockets (the classic example being the Space Shuttle), whilst reserving high specific impulse engines, especially less massive hydrogen fuelled engines for higher stages. The Space Shuttle Columbia seconds after engine ignition, 1981 (NASA). ...


But the ability of solid rockets to remain in storage for long periods, and then reliably launch at a moments notice, makes them the design of choice for very many military applications.


Amateur rocketry

Solid fuel rockets can be bought for use in model rocketry; they are normally small cylinders of fuel with an integral nozzle and a small charge that is set off when the fuel is exhausted. This charge can be used to ignite a second stage, trigger a camera, or deploy a parachute. A model rocket. ... Rocket Nozzle A nozzle is a mechanical device designed to control the characteristics of a fluid flow as it exits from an enclosed chamber into some medium. ... The second stage of a Minuteman III rocket A multistage (or multi-stage) rocket is, like any rocket, propelled by the recoil pressure of the burning gases it emits as it burns fuel. ... A camera is a device used to take pictures (usually photographs), either singly or in sequence, with or without sound recording, such as with video cameras. ... The Apollo 15 capsule landed safely despite a parachute failure. ...


Designing solid rocket motors is particularly interesting to amateur rocketry enthusiasts. The design is simple, materials are inexpensive and constructions techniques are safe.


Early amateur motors were gunpowder. Later, zinc/sulfur formulations were popular.


Typical amateur formulations in use today are; sugar (sucrose, dextrose, and sorbitol are all common)/potassium nitrate, HTPB (a rubber like epoxy)/magnesium/ammonium nitrate, and HTPB or PBAN/aluminum/ammonium perchlorate. Most formulations also include burn rate modifiers and other additives, and also possibly additives designed to create special effects, such as colored flames, thick smoke, or sparks.


Amateur rocket builders are very active in hybrid motor research.


Advanced research

  • Environmentally sensitive fuel formulations
  • Ramjets with solid fuel
  • Variable thrust designs based on variable nozzle geometry.
  • hybrid rockets that use solid fuel and throttleable liquid or gaseous oxidizer

A ramjet, sometimes referred to as a stovepipe jet, is a type of jet engine. ... A hybrid rocket propulsion system is a rocket engine composed of a solid propellant lining a combustion chamber into which a liquid or gaseous propellant is injected so as to undergo a strong exothermic reaction to produce hot gas that is emitted through a De Laval nozzle for propulsive purposes. ...

References

  1. Sutton, George P. (2000). Rocket Propulsion Elements; 7 edition. Wiley-Interscience. ISBN 0471326429.

See also

A Minuteman III missile after a test launch. ... The Jetex engine was a type of solid-fuel rocket engine developed for use as a powerplant for model aircraft. ... A skyrocket is a type of firework that uses a solid rocket motor to rise quickly into the sky. ... A remote camera captures a close-up view of a Space Shuttle Main Engine during a test firing at the John C. Stennis Space Center in Hancock County, Mississippi Spacecraft propulsion is used to change the velocity of spacecraft and artificial satellites, or in short, to provide delta-v. ... A liquid rocket engine has fuel and oxidizer in liquid form, as opposed to a solid rocket or hybrid rocket. ...

External links


  Results from FactBites:
 
Solid rocket - Wikipedia, the free encyclopedia (1007 words)
A Solid rocket or a solid fuel rocket is a rocket with a motor that uses solid propellants (fuel/oxidizer).
The earliest rockets were solid fuelled, powered by gunpowder, used by the Chinese in warfare as early as the 13th century.
Solid fuel grains are usually molded from a thermoset elastomer, fuel, oxidizer and catalyst.
Solid rocket booster - Wikipedia, the free encyclopedia (402 words)
Solid rocket boosters (SRB) are used to provide the main thrust in spacecraft launches from the launchpad up to an altitude of about 45 kilometres.
Relieving the rocket or shuttle of this weight eases the amount of liquid-fuel needed and lowers the launch vehicle mass.
Solid rocket motors cannot easily be turned off or have their thrust terminated during flight, which is a risk factor for manned spacecraft.
  More results at FactBites »

 
 

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