Talk:Bussard ramjet

message: 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/talkedits> 20:48, 26 December 2007 (UTC)
replies: text: I agree entirely. "Ram scoop" should be merged into this one. DanielCristofani (talk) 10:03, 28 July 2008 (UTC)
thread_title: Ram Scoops Separate Article

message: 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)
thread_title: Fusion Reactions

message: 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)
thread_title: Ramjet speed

message: 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)
replies: text: You forgot about relativistic effects - haven't you heard that speed of light is unattainable for objects with non-zero rest-mass? Mithoron (talk) 01:38, 20 January 2015 (UTC)
thread_title: Time to achieve light speed

message: 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)
replies: text: -That depends on what speed the ramjet reaches on internal fuel before attempting to initiate ram collection. Obviously the thinner the density of hydrogen in interstellar space, the higher velocity you need to be at to collect enough to maintain sufficient fuel supply. It is also obvious that any ramjet vessel will begin its journey inside a solar system where hydrogen densities are much higher from solar wind. The real question is that as the vessel gains speed and exits the solar system, whether the declining hydrogen density is sufficient at the higher velocity to maintain fusion. Also note that if hydrogen is less dense, this also means that drag would also be lower.75.67.80.68 (talk) 01:46, 22 May 2009 (UTC)

text: Interstellar space contains about 1 hydrogen atom per cubic centimeter.  This means the total swept out volume of 1 light-year by 1 square kilometer contains only about 10 kilograms of hydrogen. DonPMitchell (talk) 00:13, 27 September 2012 (UTC)
thread_title: Not enough hydrogen

message: 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)
thread_title:  Non-ramjet material removed 

message: 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)
thread_title:  Deceleration 

message: 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)
replies: text: It's no more a perpetuum mobile than something propelled through water by a water-jet--like, say, a squid.  Admittedly, the ramscoop has to do more with its fuel than just squirt it out the back (it has to fuse it first), but there's no physical law being violated.  Nagakura shin8 (talk) 10:51, 6 March 2009 (UTC)
replies: text: It is more like a motorboat that can run forever because it is traveling in a sea of gasoline.  Sure there is drag from scooping the gasoline into the engine, but you get a lot more power from burning the gasoline than you lose from the drag of siphoning it into your engine.  It is the stored energy in the hydrogen atoms that is unlocked by fusion that prevents anything like perpetual motion.  It actually does expend the fuel, it is theoretically possible to deplete the free hydrogen in the interstellar medium, but practically impossible because there is just so damned much of it.  128.97.68.15 (talk) 21:24, 17 October 2012 (UTC)
thread_title:  Ramjet 

message: 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)
thread_title: Oh, John Timberlake

message: 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)
thread_title:  Where is the original paper ? 

message: 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)
thread_title:  Separate 'Cultural References' section? 

message: This section has no references. aajacksoniv (talk) 14:53, 13 January 2013 (UTC)
replies: text: Still didn't six months later so I deleted it. Pure WP:OR 202.81.243.196 (talk) 15:09, 25 July 2013 (UTC)
thread_title:  Speed Limit 

message: 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)
thread_title:  Feasibility