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	Bussard ramjet - Wikipedia, the free encyclopedia
		The Bussard ramjet method of spacecraft propulsion was proposed in 1960 by the physicist Robert W. Bussard and popularized by Carl Sagan in the television series and subsequent book Cosmos as a variant of a fusion rocket capable of fast interstellar spaceflight.
		The typical velocity of the interstellar wind is 50 km/s beyond the heliopause.
		In Coyote by Allen Steele the Starship Alabama uses a Bussard ramjet for propulsion on the journey to 47 Ursae Majoris.
	en.wikipedia.org /wiki/Bussard_ramjet (2355 words)

	Ramjet - Wikipedia, the free encyclopedia
		In a ramjet, owing to the high flight speed, the ram compression is sufficient to dispense with the need for a compressor and a turbine to drive it.
		Ramjets generally give little or no thrust below about half the speed of sound, and they are inefficient (less than 600 seconds due to low compression ratios) until the airspeed exceeds 1000 km/h (600 mph).
		Ramjets are found almost exclusively in missiles, where they are boosted to operating speeds by a rocket engine, or by being attached to another aircraft (typically a fighter).
	en.wikipedia.org /wiki/Ramjet (1302 words)

	Ramjet - Indopedia, the Indological knowledgebase
		Ramjets reduce engine complexity by eliminating most of the moving parts; the speed of an aircraft is enough to compress air at the ramjet's inlet, eliminating the need for fans.
		Ramjets essentially do not work at all below half the speed of sound, and ramjets are inefficient due to low compression ratios until the airspeed exceeds 600 mph (1000 km/h).
		Scramjets, or "supersonic combustion ramjet" are similar to Ramjets in that they rely on the ram effect for compression, but the air goes through the entire jet at supersonic speeds.
	www.indopedia.org /Ramjet.html (640 words)

	interstellar ramjet
		Set against the desirability of achieving speeds for star travel that are a significant fraction of the speed of light is the perennial problem of rocketry – having to carry, in addition to the payload, the reaction mass needed for propulsion.
		The interstellar ramjet neatly avoids this problem by harvesting hydrogen for use as a propellant from the interstellar medium.
		A modified design, known as RAIR (ram-augmented interstellar rocket), proposed by Alan Bond in 1974, tackles the fusion-reaction problem by using the scooped-up interstellar hydrogen not as fuel but simply as reaction mass.
	www.daviddarling.info /encyclopedia/I/interstellar_ramjet.html (886 words)

	Ramscoop and RAIR ships
		Bussard recognised that the interstellar medium was very thin, so his projected craft would not be able to collect enough hydrogen at low speeds; it was suggested that the ramscoop would need to exceed 6% of lightspeed to provide acceleration, and that a magnetic scoop would be required, to save mass.
		Interplanetary (or interstellar) dust and hydrogen collected by the relatively small ramscoop is used as inert propellant mass, while conserving as much of the kinetic energy of the medium as possible to avoid braking effects.
		Bussard ramscoops are also utilised in inner solar systems to sweep dust away from inhabited regions; beanstalks and other megastructures are vulnerable to micrometeorite impact, so the disruption caused by periodic magnetic dust collection is considered worthwhile.
	www.orionsarm.com /ships/Bussard_Ramscoop.html (694 words)

	Bussard Ramjet (George Herbert; Henry Spencer)
		It is reasonably obvious to anyone who does a real analysis of the Bussard ramjet instead of relying on analogy from "ordinary" jets.
		Bussard himself suspected that the interstellar medium near the Sun might be too thin to run his ramjet.
		The key problem for bussard ramjets has always been trying to deal with the energy lost accellerating the interstellar medium to ramship speed.
	yarchive.net /space/exotic/bussard_ramjet.html (1340 words)

	What Types of Interstellar Spacecraft Have Been Proposed?
		Interstellar spacecraft, or spacecraft capable of making trips between solar systems, would need to be considerably more advanced than the interplanetary craft that mankind has already constructed.
		An interstellar spacecraft would likely have to serve as an autonomous space colony, perhaps housing generations of individuals and the means for their survival and prosperity.
		Although the amount of free-floating hydrogen in interstellar spaces is diffuse, much hydrogen could be harvested if the craft were moving at near the speed of light, as its design demands.
	www.wisegeek.com /what-types-of-interstellar-spacecraft-have-been-proposed.htm (750 words)

	Bussard ramjet (Site not responding. Last check: 2007-10-23)
		It use a large scoop (on the order miles) to compress hydrogen from the interstellar medium and fuse it.
		A problem that will have to overcome is that most interstellar hydrogen is hydrogen-1 instead of the easier-to-fuse deuterium and tritium isotopes and so makes a poor fusion it is possible that this could be by using a carbon-nitrogen-oxygen catalysed nuclear cycle.
		The ramjet has been used occasionally in science fiction : Paul Anderson's 1970 novel Tau Zero is about a journey through the in a Bussard ramjet and in the Star Trek fictional universe vessels commonly have magnetic hydrogen collectors.
	www.freeglossary.com /Bussard_interstellar_ramjet (451 words)

	ITSF Brochure: Propulsion Techniques: Ram Scoop Devices
		The top speed of a Bussard ramjet is theoretically very close to the speed of light, but practically it may be hindered by the density of interstellar matter, the drag of the magnetic field and the braking of the incoming protons.
		The maximum velocity of Niven's ramjets is reached when the speed of interstellar hydrogen coming in matches the speed of the exhaust at a significant percentage of the speed of light.
		Modifications of the original ramjet concept include charging incoming neutral particles using a laser, getting the ramjet to ram speed using a light sail, boosting the thrust of the craft by anti-matter/ matter reactions, using an accelerator as an alternative reaction-mass drive – the last concept could be enhanced using fusion or anti-matter catalysation.
	www.itsf.org /brochure/ramscoop.html (1001 words)

	Interstellar Travel Summary - Interstellar Travel Information
		However, interstellar travel would be extremely difficult withcurrent technologies because of the tremendous distances to even the nearest stars, the amount of energy required, and the constraints imposed by the laws of physics.
		Although there are no specific plans in place for interstellar missions, and there are only a few spacecraft that are heading into interstellar space, a number of concepts for human and robotic spacecraft that could travel from this solar system to another star have been developed.
		Human interstellar missions may require suspended animation or the development of "generation ships," in which the descendants of the original crew members will arrive at the destination.
	www.bookrags.com /sciences/astronomy/interstellar-travel-spsc-04.html (1133 words)

	Interstellar Bussard Ramjet Propulsion System Grants (Site not responding. Last check: 2007-10-23)
		The Exotic Technologies Institute Grants for Bussard Ramjet Propulsion System The next propulsion system grant candidates are ingenious extension of many spacecraft types including the Bussard interstellar ramjet propulsion systems.
		Set against the desirability of achieving speeds for star travel that are a significant fraction of the speed of light is the perennial problem of rocketry -- having to carry, in addition to the payload, the reaction mass needed for propulsion.
		(In interstellar clouds where the average density is ~10² H-atoms/cm², a scoop with one-tenth this area would suffice.) Even assuming knowledge of materials science far in advance of our own, it seems inconceivable that such a scoop could be constructed with a mass less than that budgeted for the entire vehicle.
	www.thebridgeacrosstheuniverse.com /smallbusiness/id33.html (913 words)

	Articles: Cruising the Infinite: Strategies for Human Interstellar Travel, by Paul Lucas
		Very efficient ramjet drives could come to within a hairbreadth's of the speed of light, though some source say that a ramjet's more practical limit may be between 50% and 85% of lightspeed.
		One of the main difficulties in building a Bussard Ramjet (aside from getting it up to the minimal operational velocity of one to six percent of lightspeed) is creating magnetic fields large enough to gather enough fuel to be strong enough to handle the stresses of scooping and fusing hydrogen at significant fractions of lightspeed.
		Moving at significant fractions of lightspeed, the repeated impacts of the interstellar hydrogen on the immense ramscoop field is thought by some to offset much of the acceleration produced by the fusion engines, greatly reducing the starship's capabilities.
	www.strangehorizons.com /2004/20040621/travel.shtml (3948 words)

	Bussard Interstellar Ramjet
		Such a vehicle need not in fact draw the interstellar gas inside itself, but only be coupled to it in some manner, by electric or magnetic fields for example.
		In this phase the relative speed of the vehicle through the interstellar medium is greater than the speed of the rocket let leaving the vehicle, and so it pays to boost the jet velocity using some of the external energy in this manner.
		Hydrogen scooped from the interstellar medium by a vast magnetic field created by the vehicle undergoes cyclic reaction in a fusion reactor to convert four hydrogen atoms into one helium atom, releasing energy in the process.
	www.bisbos.com /rocketscience/spacecraft/bussardramjet/bussard.html (1103 words)

	Interstellar Spaceflight: Is It Possible? (Site not responding. Last check: 2007-10-23)
		One interesting idea is the Bussard ramjet first proposed in 1960 by the American physicist RW Bussard.
		Although commonly perceived to be empty, interstellar space has a minuscule amount of hydrogen gas - at a density of about one or two atoms per cubic centimeter.
		Bussard’s idea is to scoop this gas up using electromagnetic force fields that extend outwards in front of the spacecraft.
	www.ufoarea.com /physics_cosmology_interstellar.html (1395 words)

	The Ultimate Ramjet Dog Breeds Information Guide and Reference
		Sometimes called a stovepipe jet, a ramjet is a type of jet engine designed by William Avery.
		The basic principle of a ramjet is the same as that in a jet engine: intake, compression, combustion, exhaust.
		Ramjet propulsion was used on the British Bristol/Ferranti Bloodhound surface to air missile.
	www.dogluvers.com /dog_breeds/Ramjet (645 words)

	BBC - h2g2 - The Bussard Ramjet - An Interstellar Drive?
		An interstellar rocket, which would have to travel distances measured in light years, would therefore be enormous, and most of the fuel would be used accelerating other fuel.
		This is the "medium" for the Bussard ramjet.
		The short story is more of a cautionary tale of the unforeseeable consequences of cryonic preservation, and the novel is a fantasy of the far future, but both rely on the concept of the Bussard ramjet in passing.
	www.bbc.co.uk /dna/h2g2/A578153 (1018 words)

	Bussard ramjet (Site not responding. Last check: 2007-10-23)
		The Bussard ramjet design was proposed in 1960 by the physicist Robert W. Bussard as a variant of a fusion rocket.
		It would use a large scoop to compress hydrogen from the interstellar medium and fuse it.
		To save mass, some people have suggested using a magnetic field for a scoop.
	bopedia.com /en/wikipedia/b/bu/bussard_ramjet.html (223 words)

	The Physics of Interstellar Travel - UFO Evidence (Site not responding. Last check: 2007-10-23)
		This essay will explain the challenges of interstellar travel, the prospects and limitations of existing propulsion ideas, and the prospects emerging from science that may one day provide the breakthroughs needed to enable practical interstellar voyages.
		This Bussard Interstellar Ramjet concept, from the 1960's, relies on scooping up the lonely protons that drift in interstellar space, and then somehow getting them to fuse to make a nuclear rocket.
		The mission objective of the Voyager Interstellar Mission (VIM) is to extend the NASA exploration of the solar system beyond the neighbourhood of the outer planets to the outer limits of the Sun's sphere of influence, and possibly beyond.
	www.ufoevidence.org /documents/doc1060.htm (3560 words)

	Bussard Ramjets
		A Bussard ramjet (named after R. Bussard, who first postulated the idea) is a rocket engine which collects its fuel and reaction mass from the interstellar medium as it moves through space.
		Since the interstellar medium is highly ionised, the physical collecting funnel can be augmented by an electromagnetic field system, which will draw nuclei into the funnel from a much wider area.
		This means the acceleration of a ramjet is dependent only on the size of the collecting funnel, density of the interstellar medium, efficiency of the nuclear fusion reaction, and mass of the ship, and is a constant over time.
	www.dangermouse.net /gurps/science/ramjet.html (906 words)

	Atomic Rocket: Slower Than Light
		Accelerating at 1 g a Bussard ramjet could reach the center of the galaxy in a mere twenty years of proper time, and could theoretically circumnavigate the entire visible universe in less than a hundred years.
		The Bussard ramjet concept has gotten a lot of scrutiny, trying to derive a spin-off concept without the crippling flaws but with most of the benefits.
		In a pure Bussard ramjet, the hydrogen scooped up has to be braked to a stop, creating drag (unless you can manage to make the hydrogen fuse while it is still travelling at whatever percentage of lightspeed the starship is travelling, which is pretty darn close to being impossible).
	www.projectrho.com /rocket/rocket3aj.html (8404 words)

	Bussard Ramjet
		This was first proposed in a 1960 paper by Robert W. Bussard and popularised by Carl Sagan in the Cosmos television series (1980).
		Then there is the size of the magnetic scoop, which needs to be upwards of 50,000 kilometers in diameter to collect the needed fuel and even in the vacuum of interstellar space that can produce drag like trying to go swimming underwater while pushing a washtub in front of you.
		This has lead to some calculations that the ramjet might not be able to go faster than 16% of the speed of light.
	davidszondy.com /future/space/bussard.htm (386 words)

	Advanced Space Propulsion Study - Appendix A
		The energiesrequired to launch a manned interstellar transport are enormous, for the mass to be accelerated is large and the cruisespeed must be high.
		TheBussard interstellar ramjet [Bussard, 1960] is one example.The interstellar ramjet carries no fuel because it uses ascoop to collect the hydrogen atoms that are known to exist in"empty" space.
		In the pellet-pushed-probe concept [Singer, 1980], smallpellets are accelerated in the solar system and accuratelyguided to an interstellar probe where they are intercepted andtransfer momentum to the spacecraft.
	www.transorbital.net /Library/D001_AxA.html (2777 words)

	[No title] (Site not responding. Last check: 2007-10-23)
		This way the ship doesn't have the drag a true ramscoop would have accelerating interstellar fuel that is going much slower than the ship is. All incoming mass is hit with a short length of electric or magnetic forward thrust once it enters the ship.
		The interstellar mass, being at a far different speed and direction than the ship, will blow past the magnetic catcher into the main thrust accelerator (powered by the soon to be burned fuel).
		The problem with using an interstellar scoop, is their isn't much in interstellar space to scoop up.
	www.urly-bird.com /LIT/interstellar/Explorer_Class/RAIR_Drive.html (1545 words)

	Bussard ramjet - Engineering (Site not responding. Last check: 2007-10-23)
		However, in their calculations they assumed that: 1, the exhaust velocity of their interplanetary ion propulsion ramjet could not exceed 100,000 m/s which is 100 km/s; and, 2, that the largest available energy source could be a 500 kilowatt nuclear fission reactor.
		This condition of course resulted in the drag force exceeding the thrust of the hypothetical ramjet in the Zubrin/Andrews version of the design.
		is the mass of the collected ramjet propellant multiplied by the exchaust velocity at which it is expelled from the Ramjet engine to generate thrust.
	engineering.wikia.com /wiki/Bussard_ramjet (1563 words)

	Final Gallery
		The vastness of the universe would be impossible to explore without the ability to travel at and exceed the speed of light several times, but at the time, this is both a mathematical impossibility and a theoretical inconsistency.
		Interstellar travel at warp speeds only dreamed of in Star Trek and Star Wars would require two other major innovations to be achieved.
		It would be necessary to combine Forwardâs Interstellar Laser Sails System with a shuttle design (with Astronaut living quarters) and rovers that would be deployed as the spacecraft passed planets (see design).
	aerospacescholars.jsc.nasa.gov /has/Students/finalGall.cfm?id=1106 (1140 words)

	[No title]
		One concept that was proposed over 20 years ago was the Bussard ramjet.
		The Bussard Ramjet collects and uses the hydrogen of interstellar space as a propellant.
		The Bussard ramjet will only work when the vehicle is moving fast enough to collect enough interstellar mass.
	abyss.uoregon.edu /~js/space/lectures/lec25.html (1287 words)

	s3.1
		Bussard (ref. 3) has proposed an ingenious spaceship that would use interstellar hydrogen both as fuel and propellant.
		A sober appraisal of all the methods so far proposed forces one to the conclusion that manned interstellar flight is out of the question not only for the present but for an indefinitely long time in the future.
		Interstellar probes are appealing as long as someone else sends them, but not when we face the task ourselves.
	history.nasa.gov /SP-419/s3.1.htm (2336 words)

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