Talk:Nuclear weapon yield

message: I have added a bit on the calcualtions that G.I. Taylor used.  I'm not sure what the US military does for their calcualtions, but G.I. Taylor is well known in chemical engineering for having accurately determined the yield of weapons that only pictures were issued of without yields to accompany.  An example regarding the trinity test is provided.  Sorry about some of my grammar, but I'm an engineer, not an english major.
-MDL 01:25 08 March 2006
Added links for Trinity test and G. I. Taylor.  Listed reference for G.I. Taylor's paper on the subject.
-MDL 09:37 09 March 2006
MDL: please note that a physically-based alternative to G.I. Taylor's approach proves that the correct formula for the energy is
E={\frac {8\pi\,\rho\,{R}^5}{75(\gamma\ - 1){t}^{2}}}
and avoids the approximate integration that Taylor used: http://glasstone.blogspot.com/2006/03/analytical-mathematics-for-physical.html 172.212.100.165 11:24, 30 March 2006 (UTC)
thread_title: Estimating/measuring yield

message: One problem is that the result given in the WP section can't actually be used alone to figure out the answer, because the value of c is not given. 
"A good approximation of the yield of the Trinity test device was obtained from simple dimensional analysis by the British physicist G. I. Taylor.  Taylor noted that the radius R of the blast should initially depend only on the energy E of the explosion, the time t after the detonation, and the density ρ of the air.  The only number having dimensions of length that can be constructed from these quantities is:
 
R=c\left( {\frac{{E{t}}^{2}}{\rho}} \right)^{\frac {1} {5}}
Using the picture of the Trinity test shown here (which had been publicly released by the U.S. government and published in Life magazine), Taylor estimated that at t = 0.025 s the blast radius was 140 metres.  Taking ρ to be 1 kg/m³ and solving for E, he obtained that the yield was about 22 kilotons of TNT (90 TJ).  This very simple argument agrees within 10% with the official value of the bomb's yield, , which at the time that Taylor published his result was considered highly-classified information. (See G. I. Taylor, Proc. Roy. Soc. London A 200, pp. 235-247 (1950).)"
COMMENT: Cute, but if you go through the equation above, you find from pure dimensional analysis that "c" (not the speed of light!) is a dimensionless constant "k", but you need to know what it is, to calculate E from R. In the equation above, for example, you can estimate E from  R if you assume c is about 1, but that's a coincidence. If you have two sets of t and R (two timed stills of the blast, which I assume were available), you can show R^5/t^2 is constant, and from them you can estimte E*c^5 if you know density rho, but without a value for c you still don't know E without some further considerations about the heat capacity of air. Taylor worked by integrating the energy in air shockwaves to get a numerical esitmate of c as approximately 1. The link given shows that you can use gas dynamical estimate of the heat capacity of air to show that c^5 = 8π/[75(γ-1)] or c = [75(gamma-1)/(8pi)]1/5 which is close to 1. If you assume γ = 7/5 for a hot diatomic gas, then this gives c^5 = 0.84, or c = 0.965. That's really close to 1, all right, but again, totally coincidentally! In the paper it notes that a combination of dissociation  and vibration returned gamma coincidentally at 5000 K back to the "room temp" gamma of 1.4, so c becomes 1.036. Again, quite coincidentally close to 1, from the dimensional analysis sense.  Also, interestingly Taylor's classified work was done in 1941, and declasified along with application to the Trinity results in 1950. By then the Soviets had the atom bomb anyway, so there was no point in keeping all this a secret. I'll add some material to the main article.  BTW, Taylor used a density for air of 1.25 kg/m^3, but for the Trinity conditions it just happened to be closer to 1.0 (altitude and so on). SBHarris 23:46, 13 March 2011 (UTC)
thread_title: COMMENT on above

message: It would be really great if someone could add a section on how yield has been historically measured, and about some of the more difficult yield estimates (i.e. exactly how powerful the Trinity, Little Boy, and Nagasaki bombs were; whether the Tsar Bomba was 50 or 55 Mt, and disputed yields in relation to the India/Pakistan tests). --Fastfission 17:33, 17 November 2005 (UTC)
thread_title:  Modern methods of yield estimation 

message: The shock propagation method described above only allows to estimate the mechanical (blast) fraction of the yield. But the energy distribution between blast, thermal radiation and nuclear radiation greatly depends on the weapon type and the total yield. Bombs with large yield-to-weight ratio tend to release more energy as heat while reducing the blast fraction (between 50 and 60 according to Carey Sublette's Nuclear Weapon Archive). In fact, this variance is even larger then, e.g., the uncertainties of the yield of the Tsar Bomba (50-57 MT). Could it be the case that the 50-MT-estimate addresses the blast equivalent while the 57 MT is more closely related to the total energy yield that could be estimated e.g. by the amount of radioactive particles or simply by assuming a typical blast-to-thermal relation extrapolated from earlier tests?--SiriusB (talk) 07:56, 11 April 2008 (UTC)
thread_title: Yield estimation and energy distribution

message: "The United States claimed they had the capability of tipping a Titan II ICBM with a 35-megaton-of-TNT (150 PJ) fusion bomb. If this were the case, the yield to weight ratio would be about 9.5 megatons of TNT per metric ton (40 TJ/kg)."
The theoretical limit is stated as 25 TJ/kg in the previous passage.  Are both of these numbers right?  If so, should a sentence be added here to make this contradiction clear?  What is the source of that theoretical ceiling ?  I don't know much about this subject, but it seems like a secondary's output might be on the
order of 500 TJ/kg just based on T-D fusion and very rough math ... Obviously, there 
needs to be a primary, but what assumptions are included about the primary's design in that limit calculation?  Again I don't know much about this subject I got the 500 TJ/kg number by using a 14 MeV number for D-T and converting it to TJ/kg, perhaps, I have gotten it wrong or this is completely wrong way to think about it...  Can anyone expand on this part?
Garick  —Preceding unsigned comment added by 128.91.197.64 (talk) 16:00, 27 January 2009 (UTC)
thread_title:  Am I reading this section correctly ? 

message: In a fictional series I watch, they say that a next-generation atomic weapon is really advanced because it has an "8% blast to target ratio".  That is...actual "weapon yield" is the amount of energy released when the bomb detonates....but most of this energy is radiated outward; an explosion happens in all directions.  The bigger the bomb, according to the inverse-square law, actually the less efficient it is (i.e. a 20 megaton bomb only has 10 times the radius of a 20 kiloton bomb, not a thousand times greater).  Regardless, what is the term for this?  That is, "the amount of blast yield that actually hits the target and it not lost by being directed upwards and outwards"?  The idea was that these fictional next-generation bombs were able to "focus" a lot better, losing less of their energy to the environment but concentrating it all more efficiently.  Answer on my talk page.  --Vi Veri Veniversum Vivus Vici (talk) 20:32, 16 September 2008 (UTC)
thread_title: Blast efficiency to target

message: Wiki never stops to amaze me.
Claims to be encyclopedia, but presents nearly all US warheads, and only one soviet test. As I said, Amazing.
Mk-36 bomb had a 19 megaton yield.6 mt was clean version,but clean weapons apparently never been deployed.Source-Report of NSC AD HOC Working Group on  the technical feasibility of a cessation of nuclear testing(Hans Bethe and others).That can be found at www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB94/tb02.pdf.So that Hansen numbers wrong.  —Preceding unsigned comment added by 94.242.180.237 (talk) 10:56, 26 June 2010 (UTC)
thread_title:  Amazing. 

message: Does it strike anyone else as odd that an event that can't be confirmed to have actually occurred, let alone what parties were involved, and doesn't even have any hypothetical information for yield and name can be classified as "milestone?"  I'm not really certain of Wikipedia etiquette with regards to editing, and I don't want to screw anything up, but maybe that line in the table should be removed?  Either that or a significant amount of caveats added within the "significance" cell for the line.  As it stands now, I feel the entry is misleading and misplaced. 84.229.55.39 (talk) 08:29, 29 July 2012 (UTC)
thread_title:  "Vela Incident?" 

message: Hello fellow Wikipedians,
I have just modified 2 external links on Nuclear weapon yield. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
*Added archive https://web.archive.org/web/20051201184506/http://www.cddc.vt.edu/host/atomic/nukeffct/enw77a.html to http://www.cddc.vt.edu/host/atomic/nukeffct/enw77a.html
*Added archive https://web.archive.org/web/20060405211214/http://www.saag.org/papers5/paper451.html to http://www.saag.org/papers5/paper451.html
When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.
Cheers.—InternetArchiveBot (Report bug) 18:07, 24 January 2018 (UTC)
thread_title:  External links modified (January 2018) 

message: I came to this page trying to remember what fraction of fissile material actually fissions in a fission bomb. I know it is a little more for implosion than gun design.  It might also be nice to know for fusion bombs. Gah4 (talk) 05:25, 24 March 2021 (UTC)
thread_title:  fraction yield 

message: The article says: measurement of the energy released by TNT has always been problematic, and then quotes yields to three digits, though most are only two. Gah4 (talk) 13:12, 8 November 2021 (UTC)
thread_title:  [[sigfigs]] 

message: — Assignment last updated by SapientiaMundus (talk) 16:56, 25 April 2023 (UTC)
thread_title: Wiki Education assignment: Cold War Science