Talk:Bouncing bomb

You do not win the Victoria Cross. You are awarded the Victoria Cross. 143.81.252.12 14:59, 27 October 2006 (UTC)

Bouncing cannonballs

Given the limited adjustments and control of the variables afforded a 19th century gunner, I doubt that deliberately bouncing cannonballs was a viable technique. It is more likel;y that it was observed that cannonballs did bounce occasionally when they hit the water at the right angle. Dabbler 13:27, 7 June 2006 (UTC)

Not sure how accurate it is, but in the film "The Dam Busters", the Barnes Wallis mentions that Nelson commented on the bouncing of cannon ball off the sea during the Battle of the Nile as tactic that increased range and destructive power. KingStrato 19:03, 28 August 2006 (UTC)

Sorry if I have this wrapped entirely round my neck, but I was told when I joined the aviation industry (long, long ago) that the spherical bouncing bomb was invented well before the dates quoted in the article (early 20's?) and that it was used in trials against naval vessels. If it struck even heavily armoured ships below the water line it could penetrate the armour, and above the water line it was equally effective. It was fairly accurate, fast and deployed at a range where the aircraft of the day were able to turn away before light weapons were able to properly engage - thus giving ships a very poor defence capability. It should also be remembered that at this time deck officers in the RN were having trouble even speaking to their own flying staff, let alone the RAF, holding them and their aircraft beneath contempt. The only "proper" weapons against big ships at that time were big guns on other big ships, furthermore the torpedo was a notoriously unreliable, slow and ungentlemanly, so the whole bouncing bomb concept was buried deep and forgotten in case somebody else got one. When Barnes Wallace wanted to use "his" weapon against the dams the battle was to get the Navy to permit it to come out of the pit of secrecy in which it had been cast. Even then, he was utterly forbidden to use a spherical casing and finally had to settle for a cylindrical device. Because of the poor directional stability of the cylindrical device and the reduced structural strength the bombers had to fly much lower and slower than previously necessary. Hence the retraining of the aircrew and the reduced success rate.

Or is that a load?

Drg40 (talk) 14:54, 26 June 2008 (UTC)

Well, a major problem with the above "version" is that Wallis did start off with spherical bombs, in the sense that the actual cylinderical Upkeep was inside a spherical wooden shell. It was only the continued failure of the wooden shell and the fact that the cylinder was observed to function adequately even after all the wood had broken off that let to the cylinder being used on its own. Even so, the small Highball retained a spherical shape throughout. Nick Cooper (talk) 16:23, 29 September 2008 (UTC)

+++

Trex, 7 Feb 09: Morpurgo's biography of Wallis states that he was denied the resources to make casting a full-scale round bomb possible.

Another point - citing the US Strategic Bombing Survey for the raid resulting in limited damage to two dams is questioned. It is certain that the raid did not achieve all that had been hoped and it is acknowledged that the damage was eventually repaired. However, both the Moehne and the Eder dams were completely breached. The damage to mines, electrical generation facilities and industrial installations below them was significant; probably greater than conventional bombing could have done in a much greater time. Further, the Germans immediately diverted large numbers of troops and equipment to dam protection, resources which could have been used directly against the Allied efforts. Brickhill is always a bit 'enthusiastic', but he cites the official German analysis as estimating that dam raid was "equivalent to the loss of production of 100,000 men for several months." Hardly limited results. —Preceding unsigned comment added by 66.222.251.144 (talk) 16:54, 8 February 2009 (UTC)

In answer to questions about whether the raid was a success it should be perhaps pointed out that the objective of the raid was to attempt to destroy all three dams. Thus the raid was only 'partially' successful, the Sorpe dam remaining intact. It should also be pointed out that the area had a large number of coal mines which would be flooded by the released water which would then lead to the underground galleries collapsing, thus making the pits unusable, and the released water would also put out the fire in any blast furnaces in the Ruhr area. The fires in blast furnaces can take days to get to the right temperature once they have been extinguished, so simply putting the fires out was quite effective in delaying production of steel. So quite apart from the reduced electricity supply available from the loss of the dams, other damage was not negligible to the German war economy.

BTW, I wouldn't take too much notice of what the USSBS had to say - they had an axe to grind and were not likely to say anything good about the RAF's efforts. They were reporting on targets that had been bombed by the USAAC which, according to German eyewitness on the ground, did nothing but blow the windows in, and generally cause a minor inconvenience. The RAF would then bomb the same target at night and effectively obliterate the place, often resulting in heavy machine tools such as lathes being blown half a kilometre away. They did this at Krupp's at Essen IIRC, and also at Schweinfurt. The USSBS would then classify the damage as being due to the USAAC raid. Generally, the RAF would bomb a target at night and then the USAAC would send over a few bombers to the same target just so that they could claim to have 'bombed so-and-so'. The US media would then show pictures of damage caused by the RAF raid. The US raids would only consist of say 150-300 B-17s, carrying a couple of hundred (US) tons of small bombs, whereas the RAF raids might consist of 600-800 Lancasters and Halifaxes carrying around 2,000 tons, many of which would be 4,000lb Cookies and the even larger 8,000lb and 12,000lb bombs. They could also fly in almost any weather, and if you know European weather you know that for 8-9 months of the year its pretty lousy most of the time. So that means Blind Flying (IMC) conditions. And if you only have VFR-trained pilots operating in those weather conditions it results in errors like the Bombing of Schaffhausen in World War II. So all the while the USAAC was grounded due to bad weather (either over England or the Continent) the RAF carried on as-normal. And after the introduction of FIDO even the infamous old 'London fog' didn't stop them.

... oh, and if you watch contemporary German newsreel films of the attacks you'll see that most of them are filmed in the dark, at night ... and only the RAF flew at night. —Preceding unsigned comment added by 86.112.62.148 (talk) 12:57, 13 March 2011 (UTC)

Operation Chastise line doesn't make sense

The article currently has a line "In May 1943, Operation Chastise attacked dams in Germany's Ruhr Valley -- two were breached "with limited effect".[10]" However, the wikipedia article on Operation Chastise goes on at some length about how the Chastise dam breaches had major effects included major consequences for Germany's food supply. Either this article's line or the Operation Chastise article is wrong. Also, the wikilink from "with limited effect" in this article's line goes to Operation Crossbow, not to Operation Chastise. —Preceding unsigned comment added by 204.140.148.4 (talk) 16:32, 20 May 2009 (UTC)

This seems partly to have been addressed with "variously described as", but I've looked and see no obvious relevance in the wikilinks to the Operation Crossbow article, so I'll remove them. Nortonius (talk) 22:31, 16 July 2010 (UTC)

Highball or Upkeep?

Coming to this article knowing v little about the subject, I'm confused by the fact that, in the article, the "Highball" version is said to be spherical, and the "Upkeep" version cylindrical; yet, in the photograph of the prototype recovered from Reculver and now on display in Herne Bay, the caption clearly states that this is a "Highball", despite the fact that it's cylindrical. Could someone straighten this out please - I would like to know, for the Reculver article. Thanks.

BTW, I remember seeing at least one of these cylindrical prototypes, just like the one in the museum, in muddy areas inland of the sea wall at Reculver, when I used to holiday there regularly with my family in the latter half of the 1960s - curiously, this is precisely where the "prototype" seems to be heading in the "artist's impression", in the museum display. See also archive footage of testing at [1] for broadband, [2] for dialup, where the prototype goes clear over the sea wall! Were the prototypes really dredged up from the sea bed in the 1990s, or were they picked from the mud, inland of the sea wall? I wonder! Nortonius (talk) 08:24, 16 July 2010 (UTC)

Some progress: I've had an email back from Royal Air Force Museum London, on the basis of which I've deleted "store" from the "code name", so now it just reads "Upkeep". Contact at the museum hadn't heard of "Upkeep store", and said they "wouldn't expect a code name to include the word 'store' - it defeats the object of a code word by telling everyone that UPKEEP is a store rather than (say) an operation. It would be like saying 'OBOE navigation aid'". Hopefully more to follow from me. If you're interested, the word "store" was added to the article unsourced in this edit of March 2005. Nortonius (talk) 18:44, 3 August 2010 (UTC)

Re "store", Google searches suggest that this is no more than jargon for "bomb", or even just "any payload that might be carried by a bomber", so my guess is that it probably got added to "Upkeep" in the article by a simple misunderstanding: see e.g. here, here, here, and especially here and here. Tip: search the pages reached for the word "store"! Nortonius (talk) 11:40, 7 August 2010 (UTC)

Contemporary film of the Highball tests with the word 'Store' - "backspin of store" - used in caption here: [3] — Preceding unsigned comment added by 80.7.147.13 (talk) 15:33, 12 April 2014 (UTC)

Yes, very interesting footage. About "store" though, the point is that this was just a general term for "bomb", i.e. not part of the bomb's name. Nortonius (talk) 16:18, 12 April 2014 (UTC)

Major re-write

As I remained confused about the issues raised by me above, and no-else has piped up about them, I thought I'd look into them myself. The more I did so, the more confusion and errors I found. The result is, I've just uploaded a major re-write of the article. It won't be perfect, but hopefully it's an improvement. Nortonius (talk) 17:13, 13 August 2010 (UTC)

Why was the bomb given a spin?

A great many articles which I have come across state or imply that the spin of the bomb was needed to achieve the bounce. Is this correct? The spin may increase the apparent velocity of the bombs surface against the water but would this really have any significant effect? I suspect that the only purpose of the spin was to keep the bomb aligned and stable in flight and that spin had no direct influence on the bounce. I think this article needs to be factually checked because it states “…back-spin, which improved the height and stability of its flight and its ability to bounce…”. —Preceding unsigned comment added by 90.199.197.41 (talk) 11:42, 19 October 2010 (UTC)

The statement about the effect of the bomb's spin is currently referenced with no less than three separate sources - you're welcome to check those, or any other relevant, reliable source, and change the article if you find it in error. The article says what it does there because it's already been checked, by me, in the sources cited, but the sources are cited precisely so that you can go and check them for yourself! Of the sources cited, Flower is a book, not cheap, and hard to come by at the time of writing, Johnson is a journal article available online for a fee or through institutional access, and Sweetman is available online for free, and external links are provided in the references. As I recall from the sources, backspin increased the ricochet effect as the bomb struck the water, whereas with no spin or forward spin the bomb tended to plough into the water sooner. Nortonius (talk) 13:11, 19 October 2010 (UTC)

Spinning had two effects; one to stabilise the bomb with the gyroscopic force so that even if it hit a wave at an angle, it would continue strait. Secondly, the spin gave greater relative speed to the water, hence a greater vertical deceleration force. Flying at 220mph, ie, 354kph, the forward velocity of the bomb when it hits the water, is 97m/s, neglecting air resistance. The backward spin of a two-metre diameter bomb at 500rpm, gives an additional velocity of 50m/s, so the water hits the underside of the bomb at about v = 150m/s. The upward force due to Bernouille pressure is 1/2*rho*v^2, where rho is the density of water, 1,000kg/cubic metre. The upward decelerating force is thus 11 million Newtons/ square metre. The bomb, of about 6 tonnes weight, has a vertical speed of 20m/s, falling from an altitude of 20 metres. it is stopped and reversed within about ten centimeters of submersion. In theory it should bounce up with the same vertical velocity, but friction and drag means that subsequent bounces are lower and shorter. When on one of these bounces the bomb submerges more than its radius, the net force reverses and the bomb does not bounce. — Preceding unsigned comment added by 92.16.54.133 (talk) 08:32, 9 October 2019 (UTC)

Thanks for the considered reply. It sounds like these references are hard to check so I will take your word for it. I do still think that some further technical details on the physics of the delivery would be of interest. 90.199.197.41 (talk) 14:55, 19 October 2010 (UTC)

No problem, glad it seems to have been of some use - but ahh! More "technical details on the physics of the delivery"! From memory, Johnson is the only source to discuss physics, and he doesn't discuss the bouncing bomb directly as such, but rather describes it as an example: trying to pin down sources for the physics of delivery was for me one of the most frustrating aspects of editing this article. My impression was that everyone's so taken up with the story, the actual physics barely gets a mention - you have to comb through carefully and combine the pieces yourself! I can only hope I've done it adequately. Until someone else finds a better source, that is - or, has better knowledge of the physics, and the patience to re-work what's already in the article! That would be great... Cheers. Nortonius (talk) 15:38, 19 October 2010 (UTC)

I have read the referenced paper (#1, part 2) "Ricochet of spinning and non-spinning spherical projectiles, mainly from water Part II: An outline of theory and warlike applications". Ibid: 25–34. doi:10.1016/S0734-743X(97)00033-X". On page 28-29:

The critical angle of ricochet was known to be 18°/(p/p') l/z, where (pip') is the effective specific gravity of the bomb. However, it was necessary to increase the angle of approach and reflection much above this predicted figure if success was to be achieved. Wallis proceeded to explore the effect of spin in the ricochet process and it was soon shown that spin causing increased lift generally increased ability to ricochet on water to much above that achieved by non-spinning spheres.

and:

Thus it was proposed by Wallis to attack all the dams with back-spinning spherical bombs. The angle of the dam face at the top was 45 ° , so that once impact occurred, the rotating sphere would bounce backwards as well as upwards and later would fall, the backward spin causing it to move alongside and into contact with the dam face.

and:

The bomb was to be exploded on the dam face using a hydrostatic pistol but the entrainment of a large bubble of air, generated on plunging through the surface, apparently made for an uncertain depth of explosion. However, the air bubble was no longer carried down when adequate spin was introduced, and thus rendered the depth at which explosion should occur, controllable.

which indicate that back spin had three purposes, (1) to achieve or improve bounce, (2) to allow the bomb to stay in contact with the dam wall face and (3) to ensure that the barometric fuse operated at the correct depth. However for (1) the paper seems to say that lift achieved by the Magnus Effect(non symetrical friction of air on a spinning body) was enough to alter the angle of impact with the water below the critical angle of ricochet [18°/(p/p') l/z] so that ricochet was achieved. Accordingly, it seems to me that the spin did not directly influence bounce characteristics, but was a "workaround" to alter impact angle.

As always, I'd be interested in anyones elses views on this. 130.88.149.140 (talk) 14:14, 23 November 2010 (UTC)

The spin may have had a fourth advantage, the spin may stabalise the bomb fall so that the contact with the water is at good angles. 2.103.152.77 (talk) 18:30, 2 September 2014 (UTC)

The main purpose of the back-spin was to increase the distance that the bomb would travel on the water after dropping before the energy of the launch was expended and the bomb stopped bouncing and then sank. This is the reason the German counterpart 'Karl' used a rocket to accelerate it to higher speed for the same purpose, as the British use of back-spin in 'Upkeep' had not been discovered or deduced from the recovered example found near the wreckage of IIRC, Byers' or Rice's aircraft. — Preceding unsigned comment added by 95.149.172.230 (talk) 20:56, 26 March 2019 (UTC)

Quotation marks etc.

About this diff, showing the result of two recent edits: no offence intended, and you may disagree on some points, but...

• Vickers-Armstrong is a re-direct, owing to the fact that the company's name was "Vickers-Armstrongs": see the relevant WP page, Google the name, or look here for BAE Systems' own "heritage" page.
• Pesky quotation marks - I agree that WP's use of "these quotation marks" vs. 'these' is inappropriate, as I understand it, but there's a reason for it, see here. I always kept "these" for reported speech only, until I started editing WP...
• Square brackets when clarifying a quotation of reported speech, from a book, etc., i.e. "Wallis was trying to do his ordinary job [for Vickers Armstrongs] as well as all this…", not "Wallis was trying to do his ordinary job (for Vickers Armstrongs) as well as all this…"

I'd go through and re-edit the article myself, but they were serious edits and I didn't want to cause offence unnecessarily - there are also a lot of pesky quotation marks! Cheers. Nortonius (talk) 10:24, 3 April 2011 (UTC)

• Vickers Armstrongs. I concede the point, pleading failure to check relevant article. It was inconsistent though, and perhaps it could be examined within an overall cleanup of overlinking in this article. I have a bee in my bonnet about the silly habit of unnecessarily pluralising an organisation.
• Speech marks. I, too, was taught to use double quote marks only for quoted speech, and I don't agree to change my practice just to satisfy the spurious policy reasons quoted by WP. It seems like a lot of those I amended could simply be deleted rather than changed back.
• Square brackets. I concede this, pleading that square brackets in quotations was just off my awareness radar.
• New point, Op. Cit. Ugh. WP rightly deprecates Latin abbreviations such as this. It's archaic, obscure, redundant, and perhaps also ambiguous with the two versions of Flowers book that have differing page numbers. Just a simple "Flowers (2002), p. 99" should suffice, and save code. I'll do the job, if consensus. Personally, I also favour using page number tagged onto footnote numbers, as in 25, so we would have just one footnote for Flowers (2002) etc, but admittedly more personal taste issues there. PeterWD (talk) 11:40, 3 April 2011 (UTC)

Ok...!

• Vickers Armstrongs: bee-in-bonnet understood and I sympathise, also clean up overlinking by all means, but it was "Vickers Armstrongs", whether we like it or not.
• Quotation marks: I totally agree in style terms - the reason WP gives is that searching quotations like 'this' doesn't work properly, but that's pathetic, the software should be written so it does; but, really, rather than altering an article to suit your own preferences, wouldn't it be better to take that up with the appropriate people? As I say, I agree, and I'd do that myself, but frankly I cba. In the meantime, and however much I agree with you, changing "this" to 'this' here only introduces inconsistency within WP - after all, every publication we read is written according to a style guide, and no way are all of them going to please everyone; but, go ahead and delete any quotation marks that you think are redundant, who knows but it might be an improvement.
• Square brackets: ok, sorted!
• op. cit. etc.: just as you "don't agree to change [your] practice just to satisfy the spurious policy reasons quoted by WP", I was taught to use things like "op. cit.", and cba to change now. Can you show me where WP "deprecates" "op. cit." etc.? I've a feeling I might've seen something about this, but forget where, and can't find it now - all I can find is here, where, far from being deprecated, it's used to illustrate abbreviation. As it happens, I did once remove all such Latinisms from an article, only to have them put back again by another editor, so again it's neither something that I'd insist on, nor something that offends everyone; but equally, I don't see what's wrong with such coded abbreviations - they're of long standing (the ones I'm talking about, anyway), so can easily be learned and recognised, and, if there's one I haven't seen before, I just go to a dictionary and learn something new. They're only "archaic, obscure, redundant" etc. if you're not familiar with them. But, as I say, if you want to do the legwork and change all those refs then be my guest.

So, on the whole, fine, carry on! Nortonius (talk) 22:50, 3 April 2011 (UTC)

Thanks for continuing discourse. I understand what op. cit. means, having been taught Latin, but short of GCE 'O' level. I repeat my claim that it is redundant, since Flower (but which edition?) and page number are usually stated. In this article it's clearly ambiguous. See also WP:IBID. Disagree that WP articles in practice conform to a style guide, otherwise we wouldn't have so many alternatives such as in citation styles. Happy to clean up after my mess, perhaps leave it a while longer to allow for other contributions here.PeterWD (talk) 23:47, 3 April 2011 (UTC)

No problem. Re "Flower (but which edition?)", it's only become potentially ambiguous since another edition was added to the "References" section, but only one edition is cited in the refs. so far, so not really ambiguous at the moment, but it could become so, I agree; and, paradoxically, doesn't the addition of another edition of Flower render "op. cit." more useful, rather than redundant, since it points the reader to the edition which was referred to last? But, this is little more than quibbling! I have used "ibid.", but I wouldn't use it in WP! Yep, by all means see if anyone comments, but my experience is they won't on this article, or at least not for quite some time... In which case, I've already said I don't really object to anything you've done, I just have reservations about what we do with WP's insistence on "this" vs. 'this', so feel free and take your time, as far as I'm concerned. Cheers. Nortonius (talk) 00:14, 4 April 2011 (UTC)

Stage 1 now done. Note Foxwarren link - present use of the site and hangar is by the Cobham Bus Museum, that I hope will get its own article sometime. Search on that for images at Commons, and click through to a mapping site that also shows adjacent Silvermere lake on which Wallis carried out his own early experiments.PeterWD (talk) 16:20, 4 April 2011 (UTC)

Stage 2 now done, replacement of op. cit. occurrences. I used search and replace techniques, and sincerely hope that nothing got broken in the process. I spent more time checking than doing, but please feel free to tweak my stuff or ask me to do any corrections.PeterWD (talk) 00:17, 6 April 2011 (UTC)

Bouncing bombs do not "bounce", but "ricochet"...

... but according to the relevant Wikipedia article, a "ricochet is a rebound, bounce or skip off a surface, particularly in the case of a projectile." Is this a distinction without a difference? Moletrouser (talk) 18:46, 11 August 2013 (UTC)

Interesting – I suspect imprecise language in the Ricochet article, but I'm no physicist, so I'm not going to start looking there: instead I've made this edit, which I hope answers your question. The information I've added may be a bit too much detail on ricochet here, but, as I say, I'm not going to start fiddling with the Ricochet article. Cheers. Nortonius (talk) 20:04, 11 August 2013 (UTC)

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