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Encyclopedia > Ramjet
Schematic diagram showing simple ramjet operation, with Mach numbers of flow shown.
Schematic diagram showing simple ramjet operation, with Mach numbers of flow shown.

A ramjet, sometimes referred to as a stovepipe jet, is a form of jet engine that contains no major moving parts and can be particularly useful in applications requiring a small and simple engine for high speed use; such as missiles. They have also been used successfully, though not efficiently, as tipjets on helicopter rotors. Ramjet may refer to: Ramjet, the high speed propulsion engine free of moving parts Ramjet (Transformers), a character in the Transformers toyline Roger Ramjet, the animated television comedy Category: ... Image File history File links Broom_icon. ... Image File history File links Ramjet_operation. ... Image File history File links Ramjet_operation. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... Moving parts are the components of a device that undergo continuous or frequent motion, most commonly rotation. ... For other uses, see Missile (disambiguation). ... Tipjets refer to the jet nozzles located at the tip of some helicopter rotor blades. ... For other uses, see Helicopter (disambiguation). ...

Contents

History

The idea of the ramjet (not to be confused with the Pulse jet engine of V-1 flying bomb fame, or with the Scramjet) was patented as early as 1908 by the french engineer René Lorin. In the Soviet Union, the GIRD-08 ramjet engine was built by Yuri Pobedonostsev and test fired in 1933. In France the works of René Leduc were notable, as was that of William Avery in the United States. Leduc's Model 010 was the first-ever ramjet-powered aircraft to fly, in 1949. A pulse jet engine (or pulsejet) is a very simple form of internal combustion engine wherein the combustion occurs in pulses and the propulsive effort is a jet; a reaction to the rearward flow of hot gases. ... The V-1 (German: Vergeltungswaffe 1) was the first guided missile used in war and the forerunner of todays cruise missile. ... X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the key difference being that the flow in the combustor is supersonic. ... René Lorin is the inventor of the ramjet, which he patented in 1908. ... René Leduc was a French engineer who is much acclaimed for his work on ramjets. ... William H. Avery (1913–June 26, 2004) was an influential aeronautics engineer. ... René Leduc was a French engineer who is much acclaimed for his work on ramjets. ... René Leducs model 010, more commonly known as the Leduc experimental aircraft was the first ever aircraft powered by ramjets to fly, which it did in 1949. ... Year 1949 (MCMXLIX) was a common year starting on Saturday (link will display the full calendar) of the Gregorian calendar. ...


Design

In its simplest form a turbojet consists of an air intake, compressor, combustor, turbine and nozzle. In a ramjet, owing to the high flight speed, the inlet ram compresses the air sufficiently to eliminate the need for a turbine driven compressor. A ramjet is therefore sometimes referred to as a 'flying stovepipe', a very simple device comprising of an air intake, a combustor, and a nozzle. Normally the only moving parts are those within the turbopump, which pumps the fuel to the combustor, in a liquid fuel ramjet. Solid fuel ramjets are even simpler. Turbojets are the simplest and oldest kind of general purpose jet engines. ... A Siemens steam turbine with the case opened. ... A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume. ... 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. ... A turbopump can refer to either of two types of pump. ...


Inlet

Ramjets try to exploit the very high dynamic pressure within the streamtube approaching the air intake lip. A reasonably efficient intake will recover much of the freestream stagnation pressure, to support the combustion and expansion processes. Most ramjets operate at supersonic flight speeds and use one or more conical (or oblique) shock waves, terminated by a strong normal shock, to decelerate the airflow to a subsonic velocity at intake exit. Further diffusion is then required to get the air velocity down to level suitable for the combustor. Velocity pressure is also called fluid dynamic pressure or Q given by the equation. ... Stagnation pressure is the pressure at a stagnation point in a fluid flow, where the kinetic energy is converted into pressure energy. ... A United States Navy F/A-18E/F Super Hornet in transonic flight. ... This article is about the geometric object, for other uses see Cone. ... Introduction The shock wave is one of several different ways in which a gas in a supersonic flow can be compressed. ...


Combustor

Since there is no downstream turbine, a ramjet combustor can safely operate at stoichiometric fuel:air ratios, which implies a combustor exit stagnation temperature of the order of 2400 K for kerosene. Normally the combustor must be capable of operating over a wide range of throttle settings, for a range of flight speeds/altitudes. Usually a sheltered pilot region enables combustion to continue when the vehicle intake undergoes high yaw/pitch, during turns. Other flame stabilization techniques make use of flame holders, which vary in design from combustor cans to simple flat plates, to shelter the flame and improve fuel mixing. Overfuelling the combustor can cause the normal shock within a supersonic intake system to be pushed forward beyond the intake lip, resulting in a substantial drop in engine airflow and net thrust. Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in chemical reactions (chemical equations). ... Flight dynamics is the science of air and space vehicle orientation and control in three dimensions. ...


Nozzles

The nozzle is a critical part of a ramjet design, since it accelerates exhaust flow to produce thrust. 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. ...


For a ramjet operating at a subsonic flight Mach number, exhaust flow is accelerated through a converging nozzle. For a supersonic flight Mach number, acceleration is typically achieved via a convergent-divergent nozzle. 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. ... Diagram of a de Laval nozzle, showing approximate flow velocity increasing from green to red in the direction of flow 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. ...


Performance and control

Ramjets have been run from as low as 45 m/s (100 mph)[1] upwards. Below about Mach 0.5 they give little thrust and are highly inefficient due to their low pressure ratios.


Above this speed, given sufficient initial flight velocity, a ramjet will be self-sustaining. Indeed, unless the vehicle drag is extremely high, the engine/airframe combination will tend to accelerate to higher and higher flight speeds, substantially increasing the air intake temperature. As this could have a detrimental effect on the integrity of the engine and/or airframe, the fuel control system must reduce engine fuel flow to stabilize the flight Mach number and, thereby, air intake temperature to sensible levels. An object falling through a gas or liquid experiences a force in direction opposite to its motion. ... An F/A-18 Hornet breaking the sound barrier. ...


Due to the stoichiometric combustion temperature, efficiency is usually good at high speeds (Mach 2-3), whereas at low speeds the relatively poor compression ratio means that ramjets are outperformed by turbojets or even rockets. A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... US Smarties (by Ce De Candy) US Smarties (by Ce De Candy) In the United States, Smarties are a type of artificially fruit-flavored candy produced by Ce De Candy. ...


Ramjet Types

Ramjets can be classified according to the type of fuel, liquid or solid, and the booster.[2]


In a liquid fuel ramjet (LFRJ) hydrocarbon fuel (typically) is injected into the combustor ahead of a flameholder which stabilises the flame resulting from the combustion of the fuel with the compressed air from the intake(s). A means of pressurising and supplying the fuel to the ramcombustor is required which can be complicated and expensive. Aerospatiale-Celerg have designed a LFRJ where the fuel is forced into the injectors by an elastomer bladder which inflates progressively along the length of the fuel tank. Initially the bladder forms a close-fitting sheath around the compressed air bottle from which it is inflated, which is mounted lengthwise in the tank.[3] This offers a lower cost approach than a regulated LFRJ requiring a turbopump and associated hardware to supply the fuel.[4] The Aerospatiale Corvette first flew in 1970 and went into service in 1974. ...


A ramjet generates no static thrust and needs a booster to achieve a forward velocity high enough for efficient operation of the intake system. The first ramjet powered missiles used external boosters, usually solid-propellant rockets, either in tandem, where the booster is mounted immediately aft of the ramjet, e.g. Sea Dart, or wraparound where multiple boosters are attached alongside the outside of the ramjet e.g. SA-4 Ganef. The choice of booster arrangement is usually driven by the size of the launch platform. A tandem booster increases the overall length of the system whereas wraparound boosters increase the overall diameter. Wraparound boosters will usually generate higher drag than a tandem arrangement. Type surface-to-air, surface-to-surface Nationality UK Era Cold War Launch platform ship Target aircraft or ship History Builder British Aerospace Date of design Production period Service duration 1973 Operators UK (Royal Navy), Argentina Variants ? Number built 2,000+ Specifications Type Diameter 0. ... A 2K11 TEL in transit. ...


Integrated boosters provide a more efficient packaging option since the booster propellant is cast inside the otherwise empty combustor. This approach has been used on solid, for example SA-6 Gainful, liquid, for example ASMP, and ducted rocket, for example Meteor), designs. Integrated designs are complicated by the different nozzle requirements of the boost and ramjet phases of flight. Due to the higher thrust levels of the booster a different shaped nozzle is required for optimum thrust compared to that required for the lower thrust ramjet sustainer. This is usually achieved via a separate nozzle which is ejected after booster burnout. However, designs such as Meteor feature nozzleless boosters. This offers the advantages of elimination of the hazard to launch aircraft from the ejected boost nozzle debris, simplicity, reliability, and reduced mass and cost[5], although this must be traded against the reduction in performance compared with that provided by a dedicated booster nozzle. A 3M9 TEL with missiles erected. ... The Air-Sol Moyenne Portée (abbreviated ASMP) is a French air-launched missile with a nuclear warhead. ... The Meteor missile is a highly agile long-range air-to-air guided missile for future complex beyond-visual-range (BVR) threat scenarios built by MBDA. Meteor started out as the UK MoD Staff Requirement 1239, for a Beyond Visual Range Air-To-Air Missile (BVRAAM) system, to replace the...


Integral rocket ramjet/ducted rocket

Main article: Air-augmented rocket

These are a slight variation on the ramjet where the supersonic exhaust from a rocket combustion process is used to compress and react with the incoming air in the main combustion chamber. This has the advantage of giving thrust even at zero speed. Air-augmented rockets (also known as rocket-ejector, ramrocket, ducted rocket, integral rocket/ramjets, or ejector ramjets) use the supersonic exhaust of some kind of rocket engine to further compress air collected by ram effect during flight to use as additional working mass, leading to greater effective thrust for any...


In a solid fuel integrated rocket ramjet (SFIRR) the solid propellant is cast along the outer wall of the ramcombustor. In this case fuel injection is through ablation of the propellant by the hot compressed air from the intake(s). An aft mixer may be used to improve combustion efficiency. SFIRRs are preferred over LFRJs for some applications because of the simplicity of the fuel supply but only when the throttling requirements are minimal i.e. when variations in altitude or Mach number are limited.


In a ducted rocket a solid fuel gas generator produces a hot fuel-rich gas which is burnt in the ramcombustor with the compressed air supplied by the intake(s). The flow of gas improves the mixing of the fuel and air and increases total pressure recovery. In a Throttleable Ducted Rocket (TDR), also known as a Variable Flow Ducted Rocket (VFDR), a valve allows the gas generator exhaust to be throttled allowing control of the thrust. Unlike a LFRJ solid propellant ramjets cannot flameout. The ducted rocket sits somewhere between the simplicity of the SFRJ and the unlimited throttleability of the LFRJ. A compressor stall is either of two failure modes of an axial flow jet engine caused by a stall of the vanes of the compressor rotor. ...


Flight speed

Ramjets generally give little or no thrust below about half the speed of sound, and they are inefficient (less than 600 seconds) until the airspeed exceeds 1000 km/h (600 mph) due to low compression ratios. Even above the minimum speed a wide flight envelope (range of flight conditions), such as low to high speeds and low to high altitudes, can force significant design compromises, and they tend to work best optimised for one designed speed and altitude (point designs). However, ramjets generally outperform gas turbine based jet engine designs and work best at supersonic speeds (Mach 2-4)[6]. Although inefficient at slower speeds they are more fuel-efficient than rockets over their entire useful working range up to at least Mach 5.5. This page is about the physical speed of sound waves in a medium. ... Specific impulse (usually abbreviated Isp) is a way to describe the efficiency of rocket and jet engines. ... An aircrafts performance limits, specifically the curves of speed plotted against other variables to indicate the limits of speed, altitude, and acceleration that a particular aircraft can not safely exceed. ... A United States Navy F/A-18E/F Super Hornet in transonic flight. ... An F/A-18 Hornet breaking the sound barrier. ... This article is about vehicles powered by rocket engines. ...


Ramjets top speed is limited by disassociation to about Mach 5.5.


Related engines

Air turbo ramjet

Another example of this is the Air Turbo Ramjet (ATR) which operates as a conventional turbojet at subsonic speeds and a fan assisted ramjet at speeds below Mach 6. The Air Turbo Ramjet (ATR) is an aircraft engine that operates as a conventional turbojet at subsonic speeds and a fan assisted ramjet at speeds below Mach 6. ...


Scramjets

Main article: Scramjet

Ramjets always slow the incoming air to a subsonic velocity within the combustor. Scramjets, or "supersonic combustion ramjet" are similar to ramjets, but the air goes through the entire engine at supersonic speeds, eliminating the creation of a strong shock wave in the intake. This increases the stagnation pressure recovered from the freestream and improves net thrust. Owing to the hypersonic (rather than supersonic) flight speeds experienced, scramjet air intake temperatures are too high for burning kerosene, so hydrogen is normally used as the fuel. Thermal choking of the exhaust is avoided by having a relatively high supersonic air velocity at combustor entry. Fuel injection is often into a sheltered region below a step in the combustor wall. Although scramjet engines have been studied for many decades it is only recently that small experimental units have been flight tested and then only very briefly (e.g. the Boeing X-43).[7] X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the key difference being that the flow in the combustor is supersonic. ... X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the key difference being that the flow in the combustor is supersonic. ... Boeing X-43 at Mach 7 In aerodynamics, hypersonic speeds are speeds that are highly supersonic. ... NASA technicians working on the X-43A at the tip of a Pegasus rocket attached to a Boeing B-52B prior to launch (March 27, 2004) The X-43 is an unmanned experimental hypersonic aircraft design with multiple planned scale variations meant to test different aspects of highly supersonic flight. ...


Precooled engines

A variant of the pure ramjet is the 'combined cycle' engine, intended to overcome the limitations of the pure ramjet. One example of this is the SABRE engine; this uses a precooler, behind which is ramjets as well as turbine machinery. French naval officers sabre of the 19th Century From left to right: two bayonets, a short curved infantry or artillery briquet, a straight infantry officers sabre, and a carbine. ...


The ATREX engine developed in Japan is an experimental implementation of this concept. It uses liquid hydrogen fuel in a fairly exotic single-fan arrangement. The liquid hydrogen fuel is pumped through a heat exchanger in the air-intake, simultaneously heating the liquid hydrogen, and cooling the incoming air. This cooling of the incoming air is critical to achieving a reasonable efficiency. The hydrogen then continues through a second heat exchanger position after the combustion section, where the hot exhaust is used to further heat the hydrogen, turning it into a very high pressure gas. This gas is then passed through the tips of the fan providing driving power to the fan at sub-sonic speeds. After mixing with the air it's then combusted in the combustion chamber. The ATREX engine developed in Japan is an experimental precooled jet engine that works as a turbojet at low speeds and a ramjet up to mach 6. ... A heat exchanger is a device built for efficient heat transfer from one fluid to another, whether the fluids are separated by a solid wall so that they never mix, or the fluids are directly contacted. ...


Nuclear powered ramjets

Main article: Project Pluto

During the Cold War the United States designed and ground-tested a nuclear-powered ramjet called Project Pluto. This system used no combustion - a nuclear reactor heated the air instead. The project was ultimately canceled because ICBMs seemed to serve the purpose better, and because a low-flying missile would have been highly radioactive. On January 1, 1957, the U.S. Air Force and the U.S. Atomic Energy Commission selected the Lawrence Livermore National Laboratorys (LLNL) predecessor, the Lawrence Radiation Laboratory, to study the feasibility of applying heat from nuclear reactors to ramjet engines. ... For other uses, see Cold War (disambiguation). ... On January 1, 1957, the U.S. Air Force and the U.S. Atomic Energy Commission selected the Lawrence Livermore National Laboratorys (LLNL) predecessor, the Lawrence Radiation Laboratory, to study the feasibility of applying heat from nuclear reactors to ramjet engines. ... Core of a small nuclear reactor used for research. ... A Minuteman III missile soars after a test launch. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ...


J58

The SR-71's Pratt & Whitney J58 engines act as turbojet-assisted ramjets at high-speeds (Mach 3.2). The Lockheed SR-71, unofficially known as the Blackbird, is a long-range, advanced, strategic reconnaissance aircraft developed from the Lockheed A-12 and YF-12A aircraft by Lockheeds Skunk works, which was also responsible for the U-2 and many other advanced aircraft. ... The Pratt & Whitney J58 (also known as the JT11D) was the jet engine used on the Lockheed SR-71 Blackbird. The J58 produced 32,000 lbf (142 kN) of thrust. ...


Ionospheric ramjet

The upper atmosphere above about 100km contains monatomic oxygen that has been produced by photochemistry by the sun. A concept was created by NASA for recombining this thin gas back to diatomic molecules at orbital speeds to power a ramjet.[8]


Bussard ramjet

Main article: Bussard ramjet

The Bussard ramjet is a space drive that fuses interstellar wind and exhausts it at high speed from the rear of the vehicle. Artists conception of a Bussard ramjet. ...


References

  1. ^ RAMJET PRIMER
  2. ^ "A Century of Ramjet Propulsion Technology Evolution", AIAA Journal of Propulsion and Power, Vol.20, No.1, January - February 2004
  3. ^ "Aerospatiale studies low-cost ramjet", Flight International, 13 - 19 December 1995
  4. ^ "Hughes homes in on missile pact", Flight International, 11 - 17 September 1996
  5. ^ Procinsky, I.M., McHale, C.A., "Nozzleless Boosters for Integral-Rocket-Ramjet Missile Systems, Paper 80-1277, AIAA/SAE/ASME 16th Joint Propulsion Conference, 30th June to 2nd July 1980
  6. ^ [1]
  7. ^ "Boeing: History -- Chronology 2002-2004"
  8. ^ PRELIMINARY SURVEY OF PROPULSION USING CHEMICAL ENERGY STORED IN THE UPPER ATMOSPHERE By Lionel V, Baldwin and Perry L. Blackshear

Aircraft using ramjets

The Hiller HOE (Hornet) was a helicopter powered by ramjets located on the tips of the rotor produced around 1954. ... René Leducs model 010, more commonly known as the Leduc experimental aircraft was the first ever aircraft powered by ramjets to fly, which it did in 1949. ... The D-21 mounted on the back of the M-21 - Photo: Lockheed The Lockheed D-21 was a Mach 3+ reconnaissance drone that began development in October 1962. ... This aircraft article has not been updated to WikiProject Aircrafts current standards. ... Griffon II The Nord 1500 Griffon was the prototype of a ramjet-powered fighter aircraft designed and built in the mid-1950s by French state-owned aircraft manufacturer Nord Aviation. ... The Republic XF-103 Thunderwarrior was an American project to develop a Mach 3 interceptor aircraft to destroy Soviet bombers. ... SR-71 redirects here. ...

Missiles using ramjets

Bomarc missile launch The Bomarc Missile Program was a joint United States of America-Canada effort between 1957 and 1971 to protect against the USSR bomber threat. ... The BrahMos is a supersonic cruise missile that can be launched from submarines, ships, aircraft or land. ... Bloodhound Mk 2 Type SAM Nationality UK Era Cold War Launch platform Fixed installation Target High altitude bomber History Builder Bristol Aeroplane Co. ... A RIM-8G missile. ... The SM-64 Navaho was the last-built in a line of intermediate-range ballistic missiles designed by North American Aviation in the late 1950s for the U.S. Air Force. ...

See also

  • Wikibooks: Jet propulsion

A ram accelerator is a gun that utilizes ramjet compression to accelerate a projectile to extremely high speeds. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... X-43A with scramjet attached to the underside at Mach 7 A scramjet (supersonic combustion ramjet) is a variation of a ramjet with the key difference being that the flow in the combustor is supersonic. ... // Calculations TS Diagram Typical Temperature vs. ... Jet aircraft are aircrafts with jet engines. ... A rider on a Yamaha Waverunner XL performing a high-speed turn A jetboat is a boat propelled by a jet of water ejected from the back of the craft. ... Schematic diagram of high-bypass turbofan engine CFM56-3 turbofan, lower half, side view. ... Turbojets are the simplest and oldest kind of general purpose jet engines. ... A schematic diagram showing the operation of a turboprop engine. ... Schematic diagram showing the operation of a simplified turboshaft engine. ... A Pratt and Whitney turbofan engine for the F-15 Eagle is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. ... 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 any method used to change the velocity of spacecraft and artificial satellites. ... A supercharger (also known as a blower) is an air compressor used to force more air (and hence more oxygen) into the combustion chamber(s) of an internal combustion engine than can be achieved at ambient atmospheric pressure (natural aspiration). ... Air foil bearing-supported turbocharger cutaway made by Mohawk Innovative Technology Inc. ... This machine has a single-stage centrifugal compressor and turbine, a recuperator, and foil bearings. ... Artists conception of a Bussard ramjet. ... This article is being considered for deletion in accordance with Wikipedias deletion policy. ...

External links

а Aviation encompasses all the activities relating to airborne devices created by human ingenuity, generally known as aircraft. ... This is a timeline of aviation history. ... This list of aircraft is sorted alphabetically, beginning with the name of the manufacturer (or, in certain cases, designer). ... This is a list of aircraft manufacturers (in alphabetic order). ... List of aircraft engines: // Two- and four-stroke rotary, radial, inline. ... This is a list of aircraft engine manufacturers both past and present. ... This is a list of airlines in operation (by continents and country). ... This is a list of air forces, sorted alphabetically by country, followed by a list of former countries air forces. ... This is an incomplete list of aircraft weapons, past and present. ... Below is a list of (links to pages on) missiles, sorted alphabetically by name. ... A Boeing 720 being flown under remote control as part of NASAs Controlled Impact Demonstration The following is a list of Unmanned aerial vehicles developed and operated by various countries around the world. ... This is a list of experimental aircraft. ... // This is a list of notable incidents and accidents involving military aircraft grouped by the year that the incident or accident occurred. ... This list of notable accidents and incidents on commercial aircraft is grouped by the years in which the incidents or accidents occurred. ... // This list of notable accidents and incidents involving general aviation is grouped by the years in which the incidents or accidents occurred. ... This is a list of some well-known people who have died in aviation-related events. ... The SR-71 Blackbird is the current record holder. ... Flight distance records without refueling. ... It has been suggested that this article or section be merged with List of altitude records reached by different aircraft types. ... The flight endurance record is the amount of time spent in the air. ... Aircraft with a production run greater than 5,000 aircraft. ... Transcontinental air speed record In-flight and on-ground time is counted 1929 Frank Hawks 1937 Howard Hughes Junior transcontinental air speed record For the junior record only in-flight time is counted 1929 Richard James 1930 Stanley Boynton East to West, 24 hours, 2 minutes in 6 days 1930...


  Results from FactBites:
 
Ramjet Propulsion (547 words)
In a ramjet, the high pressure is produced by "ramming" external air into the combustor using the forward speed of the vehicle.
The combustion that produces thrust in the ramjet occurs at a subsonic speed in the combustor.
Because the ramjet uses external air for combustion, it is a more efficient propulsion system for flight within the atmosphere than a rocket, which must carry all of its oxygen.
  More results at FactBites »

 
 

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