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Why does the ram scoop concept have a separate article? It seems to me that it is essentially the same concept. Plus, the ram scoop article is terribly short and uninformative. Why not merge it with this one? < ~Zebraic/ talk edits> 20:48, 26 December 2007 (UTC)
Those fusion reactions on the page are completely fudged. D-D Fusion is NOT 17MeV, it's around 3. And that's by far the most likely operating mechanism of this design. Tritium is rare on earth, it's needle-in-a-haystack in the interstellar medium. —Preceding unsigned comment added by 76.174.13.182 ( talk) 05:18, 19 March 2010 (UTC)
anybody want to talk about ramjets? —The preceding unsigned comment was added by Tmayes1999 ( talk • contribs) on 09:34, 12 June 2005.
I have a question about ramjets: In the section about the example ramjet design the solar wind velocity relative to the ramjet scoop in interstellar space is said to be 50km/s. But what about when the ramjet exceeds this speed? How can a ramjet approach the speed of light if it keeps getting pushed back by the interstellar medium? Can someone put up an example of what would happen if the ramjet was travelling at, say, 0.9c? Felix Dance 04:20, 9 November 2005 (UTC)
I don't understand how the calculation was made to get to just 77% of light speed in a year at 10 m/s/s acceleration. Taking 299,792,458 m/s (light speed) and dividing it by 60*60*24 * 10 (s/day * 10 m/s/s), I get to 100% light speed in 347 days. 107.138.117.80 ( talk) 00:47, 20 January 2015 (UTC)Jon Coombs
"The typical velocity of the solar wind within the solar system is 500 km/s."
In the article this is taken as drag. Now, since we still are within the solar system at the time, then this should be taken as draw (or push), instead of drag. The solar wind is outwards, which also is the direction of the spaceship.
Thus, when still within the solar system, it can enjoy capturing a solar wind of 500km/s, and thrusting its ions back to the same direction, "winning both ways", so to speak. —The preceding unsigned comment was added by 80.186.145.218 ( talk • contribs) on 00:17, 17 December 2005.
Ignoring the velocity of the solar wind, does drag not scale as velocity squared, whilst thrust scales as velocity? Take limits for VMax? —The preceding unsigned comment was added by 155.198.10.247 ( talk • contribs) on 12:31, 8 January 2006. If the drag is from the electrostatic force of the particles being drawn in, do those particles not give an equal and opposite force to the device which generates the electrostatic field? That is, is not the "drag" actually somehow pulling the vessel forward, since you are charging particles only forward? Or at worst, a net wash in force, at least at low speeds, as particles behind the ship drawn in would slow it, and particles in front would pull it? however, once you start to clear a wake, that will no longer be the case, as you will be travelling through a region cleared of material by the scoop.
That is, it seems to me that the drag is not in accordance with the properties of physics as I know it.
Jonathan Schattke
I wouldn't edit the main article directly, I just made this account, but I *am* an astrophysicist.
Now, the whole idea of a scoop fails miserable because particles hitting the collector at an angle (to be scooped up) will either 1) go right through, or 2) bounce back again at an angle depending on the shape of the scoop. The point is that it is not trivial to get the particles that hit the scoop concentrated in to the engine. In fact, you might as well ditch the scoop all together.
When an electrostatic field is used for ion collection the electrostatic attraction force of the charged grid on the ions will prevent scooped ions from bouncing out of the ramscooop. Tmayes1965
The effective area of the scoop will never be larger than the size of your engine. You would be riding a giant cylinder and I'm afraid the time needed to build up any appreciable acceleration would be too long for any practical purposes.
Odegard 05:01, 12 February 2006 (UTC)
There are some well known calculations that show there is not enough intersteller hydrogen for the ramjet to work. That seems to be the primary issue of feasability. DonPMitchell 04:25, 15 March 2006 (UTC)
I'm neither a mathematician nor an astrophysicist, but there seem to be a couple of things off in the calculation that don't conform to normal rules regarding drag and energy calculatons.
The first is the actual "stopping power" of the shield. As you speed would increase, the relative speed of the ions woul increase as well. At some point you shield would need to be abe to stop and funnel to the engine particles at very, very high speeds. My guess is that this alone will cause a hard cut-off point in your speed. Unless the engine is the same size as you disc, which seems imposible from an engineering point of view.
The second problem is that your drag will increase with your speed as well. If your engine exhaust speed is 500.000m/s, then this seems to be your maximum speed in deep space (when the effect of positive solar winds are trivial). Since you captured ions will hit you shield at 500.000m/s, and you also spit them out at the same speed. I've seen nothing in the description about the initial impact speed of the ion being preserved and te exhaust speed being added to it, so I must assume that the exhaust speed is the maximum speed.The ions will exit the ramjet engine at a much higher velocity, then the velocity at which the ions enter the scoop because the ramjet engine accelerates the ions .tmayes1965
The third problems is that the system still seems to require a lot of fuel just to get started and get it past a speed where enough ions are collected to power the shield, the engine and any power overhead some of the suggested might require (a fussion reactor requires a lot of initial energy).Nuclear fission can also power ramjets. It does not have to be nuclear fusion to power them.tmayes1965
Janbart
I've removed this material --
" It could also be an inertial confinement fusion reactor in which pellets of lithium 6, or lithium 7 deuteride, undergo Teller-Ulam radiation implosion by high energy laser beams, maser beams, or proton or antiproton particle beams. This will heat and compress the fusion fuel pellet until its temperature is more than 100,000,000 degrees Celsius, and increase the density of the fusion plasma by up to 30 times. This will ignite nuclear fusion in the fusion fuel pellet.
-- because it isn't about ramjets, and maser beams and antiproton particle beams aren't among the plausible ways to ignite inertial confinement fusion reactions. 67.117.145.211 03:58, 27 December 2006 (UTC) Your wrong about that . Go learn about the AIMStar project at the nuclear engineering department of pennsylvania state university . tmayes1965
I deleted this paragraph about electrostatic scoops because it seemed unclear:
The flux of the interstellar galactic electric field is 1.6 * 10^ -19 electron volts. This means that an electric ion ram scoop field will have an ion collection radius that is the square root of 1013 times (about three million times) greater than the ion collection radius of the electromagnetic ion ramscoop.
First, fields are not measured in electron volts. Second, there is not enough information to determine how the author does an apple-to-apples comparison of electrostatic scoops to electromagnetic scoops. Third, there's no citation. Is this an original calculation by the author of the section, or is there a reference for this calculation? Geoffrey.landis 21:00, 27 June 2007 (UTC)
I'm no astrophysicist, but i'm wondering how a bussard ramjet travelling to another star system would decelerate as it arrives. If it is travelling (presumably) at fractions of light speed, how could the magnetic funnel retrieve enough H to power the engines when the spacecraft was travelling in reverse relative to its motion? Unless the engines were reoriented i suppose. Perhaps this could be included in the article. Dallas 15:35, 14 July 2007 (UTC)
Ok, assume a working ramjet is designed and several are built for intra-system exploration - travel to the other planets, asteroid mining and whatnot. Wouldn't space around Earth quickly become depleted of viable fuel? Or would galactic rotation ensure that there is always a fresh supply? Applejuicefool ( talk) 21:37, 15 January 2008 (UTC)
Article needs to have calculations for using stored antimatter onboard as a power source when combined with scooped matter. —Preceding unsigned comment added by 72.200.76.139 ( talk) 03:19, 1 August 2008 (UTC)
This thing sounds somewhat like a perpetuum mobile. Is it? If it accelerate by collecting fuel from 'empty' space, and traverse increasingly more of space as acceleration increase, then fuel intake should increase as well, leading to yet higher acceleration, resulting in yet more traversal of space, resulting in yet more fuel, and hence yet more acceleration, ad infinitum (or maybe rather 'ad lightspeed'). I don't think the article is very clear on this effect, if it covers it at all. —Preceding unsigned comment added by 83.89.0.118 ( talk) 18:40, 14 August 2008 (UTC)
Who';s the MORON who redirected "Bussard Collector" into "Bussard Ramjet?!?!?!?!?!?!
Whoever did it needs to be backhanded for doing things backwards! If you're going to redirect, it should be Ramjet into Collector!
Fix your goof or take a hike!
75.8.36.225 ( talk) 23:34, 19 January 2009 (UTC)
Just noticed "Consider also the case of a wessel leaving a star system", once more a star trek reference leaks into a "science" article —Preceding
unsigned comment added by
94.194.42.49 (
talk) 22:30, 26 April 2009 (UTC)
lol @ "It is the title of John Timberlake's book[6] where he addresses notions of realism and fiction in photography and their proximity to constructions of utopias/dystopias. Interweaved with his images and bearing on 9/11, fusion-theory and space travel, John Timberlake’s compelling, three part narrative weaves Sci-Fi with contemporary realism to counter tarnished and myopic notions of 'future' civilisation and landscape." —Preceding unsigned comment added by 67.85.36.128 ( talk) 05:11, 20 April 2010 (UTC)
Why is: Robert Bussard, “Galactic Matter and Interstellar Flight,” Astronautica Acta Vol. 6 (1960), pp. 179–94 not referenced? aajacksoniv ( talk) 22:29, 3 September 2012 (UTC)
It may be a good idea to move the cultural references from the first paragraph to their own section. This would allow for a clearer distinction between the scientific issues and the portrayal of the technology in science fiction works as well as easier integration of other cultural reference not currently included in this article. (e.g. The vessel Red Dwarf in the Brittish sci-fi sitcom of the same name was intended as a ramjet - link)
Prosthetic Head ( talk) 19:10, 11 November 2012 (UTC)
This section has no references. aajacksoniv ( talk) 14:53, 13 January 2013 (UTC) Neglected is miss spelled. aajacksoniv ( talk) 14:54, 13 January 2013 (UTC)
This wiki article needs to be updated. Saying that "the bremsstrahlung losses from compressing protons to fusion densities exceeds the power that could be produced by a factor of about 1 billion", ignores the last four decades of fusion research. Particularly, suppression of bremsstrahlung losses enables dense plasma focus to attain billion degree temperatures. What was considered to be infeasible in 1975 is something to include for historical context only. -- 135.23.66.249 ( talk) 06:47, 28 November 2017 (UTC)
Where is the source citation for the Zubrin/Andrews analysis indicated by "Robert Zubrin and Dana Andrews analyzed one hypothetical version of the Bussard ramscoop and ramjet design in 1985". Without a direct reference to the article paper or work where this analysis was performed there is no method to verify that this is what Zubrin and Andrews actually said. This analysis reference should be cited or this entire section should be removed as lacking foundation. 47.135.194.69 ( talk) 17:05, 4 January 2022 (UTC)