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The Cannons on the B-29 Bomber
- rangibaby 11y agoLinkbait title. They built something complex, but who knows if it was good or not?
- Kurtz79 11y ago"It was a plane so advanced, we wrote in June 1945 about how one crew fought off 79 fighter planes, downing 7 of them, during a bombing run on Kyushu, Japan. Its weapons platform was so dominant that fighter escorts were no longer strictly necessary—as Major General Curtis LeMay put it simply: "These big boys can take care of themselves."
- rangibaby 11y agoRemember that the war was basically over at that point, and they were fighting against an enemy starved of resources and experienced manpower, particularly pilots (cf. kamikaze tactics). The "79 fighter planes" claim doesn't pass the sniff test to me either. Remember that two months after this, the Japanese didn't even bother sending fighters to even try to intercept the planes that bombed Hiroshima (for example). I'm not saying that the claim is definitely false, but I wouldn't take anything written in the press during the actual war at face value.
- hydrogen18 11y agoI always figured the Japanese assumed the plane in the case of Hiroshima was a reconnaissance plane gathered ground photographs and checking on the weather. As you correctly noted, they didn't have many resources. I'd figure a lone reconnaissance plane would rank pretty low on the list of targets they were trying to intercept.
- LordKano 11y agoThat's a common interpretation of the Japanese reaction. I admit to a limited amount of knowledge on this subject but I have never seen anything that contradicts that view.
- Raphmedia 11y agoEven a lone bomber plane would not have been that much of a threat at this point. Bomb the weapon factories, the war is over. If they had known what was coming they would have deployed a lot more and evacuated the civilians. We all know what happened instead.
- jessaustin 11y agoThe "79 fighter planes" claim doesn't pass the sniff test to me either. Remember that two months after this, the Japanese didn't even bother sending fighters to even try to intercept the planes that bombed Hiroshima (for example). The first proposition is a reasonable explanation for the second. If you're not willing to lose 79 fighters, then don't engage a B-29.
- Blackthorn 11y agoHonestly that sounds like bullshit to me. See the Clash of Wings documentary, episode 11, for more about the bombing of Japan with the B-29.
- dandare 11y agoSummary please?
- Blackthorn 11y agoFew different points made in that episode, some relevant to this discussion some not and some I'm not remembering. 1) The B-29s had god-awful bombing accuracy in their original mission (high altitude level bombing) because of the as-of-yet-undiscovered jet stream over Japan. So when they flew too high and fast to be intercepted, they were basically useless when it came to doing damage. 2) This was already in the Kamikaze era of the war, and many B-29s were lost to that. Anyway, I'm not going to rewatch the whole 45-minute long episode again. I found some stats that listed a total of 74 lost from fighters, but I'm hesitant to post because I can't dig up the original source (it 404s now). Will if you so desire. The number lost due to weather, mechanical failure, etc., dwarf the number lost to fighters by a huge factor but it does make the original quote here sound like some amount of propaganda bullshit.
- RockyMcNuts 11y agoThe engines initially had a habit of catching fire and burning the wings off. http://www.fighter-planes.com/info/b29.htm http://www.fighter-planes.com/info/b29.htm (search for magnesium)
- dceddia 11y agoNearly as bad as if the front fell off! (https://www.youtube.com/watch?v=3m5qxZm_JqM https://www.youtube.com/watch?v=3m5qxZm_JqM)
- Tloewald 11y agohttp://www.historylink.org/index.cfm?DisplayPage=output.cfm&File_Id=3828 http://www.historylink.org/index.cfm?DisplayPage=output.cfm&... There's a recorded instance of a B29 shooting down 14 fighters over Tokyo (it was also rammed by two fighters and still made it home). There are also instances of B29s downing MiGs over Korea. The late model B17s were pretty effective too. An old Strategy & Tactics magazine quoted stats for two different air forces (recall it was the "US Army Air Corps" and "Air Forces" were simply an organizational unit) operating out of Britain over a two year period in WWII, one was bombers and the other fighters. Both shot down roughtly the same number of planes -- but the bombers used 100x as much ammunition. (Sorry, this is a 1970s print publication, no link, just my memory.) Also recall that the Japanese lost almost all their trained pilots early in the war, so the B29 was using a far superior weapon system against very inexperienced pilots.
- Pinckney 11y agoKill claims are notoriously overestimated during this period, frequently by ratios of 5:1 or more. The only reliable way to estimate kills is to look at enemy records and see how many aircraft were recorded as lost during a given period. Take a look at some of the entries here; April 17th stands out. https://en.wikipedia.org/wiki/Confirmation_and_overclaiming_of_aerial_victories_during_World_War_II https://en.wikipedia.org/wiki/Confirmation_and_overclaiming_... "the 91st and 306th Bomb Groups claimed 63 German fighters destroyed, plus 15 probable and 17 damaged. Only two were confirmed destroyed, with nine damaged."
- alricb 11y agoThey're talking about M2 .50 heavy machine guns; the B-29 didn't have what are considered "cannons" (usually 20 mm or more). For the most part, defensive guns on bombers weren't all that useful; even with a fire-control computer aiding you, it's very hard to hit a (possibly maneuvering) moving plane from another moving plane. It would probably have been better to omit those heavy guns and turrets and to leave those gunners on the ground to save weight, lives, and resources.
- cstross 11y agoLater on, they did exactly that: from about February onwards, Curtis LeMay had the guns and turrets stripped out of the force bombing Japan -- except for the tail position -- to save weight/increase range, speed, and bomb load. Operational consequences: https://en.wikipedia.org/wiki/Bombing_of_Tokyo https://en.wikipedia.org/wiki/Bombing_of_Tokyo
- ckozlowski 11y agoRepeated on the B-36 as well. http://www.airvectors.net/avb36.html http://www.airvectors.net/avb36.html
- gaius 11y agoIt would probably have been better to omit those heavy guns and turrets and to leave those gunners on the ground to save weight, lives, and resources That is exactly what Freeman Dyson said of the Lancaster bomber. Tho' no sooner had the belly turret been removed than the Luftwaffe invented upward-firing guns, they would slip into position directly under, matching speed and heading, then just let rip.
- _Codemonkeyism 11y agoAnd Germany - and the world at large - was at the edge of ground-air missles [1], making cannons on bombers obsolete. [1] https://en.wikipedia.org/wiki/Rheintochter https://en.wikipedia.org/wiki/Rheintochter https://en.wikipedia.org/wiki/List_of_German_guided_weapons_of_World_War_II#Surface-to-air_missiles https://en.wikipedia.org/wiki/List_of_German_guided_weapons_...
- ZanyProgrammer 11y agoThe "edge" as in "napkin weapons that would've never have been able to have been deployed and worked, effectively"
- VLM 11y agoIt was called flak and was quite effective. The Germans also deployed air to air missiles that were basically rockets with flak warheads on them. See the bomber guns had an effective range of 1000 yards or whatever so if you stood off 1200 yards in your ME-109 and launched rockets that blew up in 1200 yards that worked pretty well. I've read a couple memoirs of WWII pilots, interesting stuff. I'm pretty sure they're all dead now, whats documented out there is all we'll ever have. As for effectiveness, well, bomber aircraft losses were tremendous until the end of the war, yet they lost the war anyway. So its hard to say. If you can down 10% of the B-17 per bombing run against ball bearing factories, but still lose the war, was it effective or not? Or looking at the staggering economic and logistics costs of the air war, skipping the air war and focusing on shipping over tanks that don't suck might have ended the war in '44 or earlier, so maybe it was ineffective. Imagine if the winter battle of the bulge never happened because the war was already over by winter rather than lasting till spring. Or maybe no bombing would have meant more hardware would have meant the D-day invasion getting pushed back into the sea Dunkirk II style. Its an evenly balanced enough argument that academics will never lack for discussion topics.
- scurvy 11y agoI doubt that they've all passed away. My great uncle was a WWII B17 navigator, and he's still alive (and quite active).
- madaxe_again 11y agoThis article makes it out like gunning computers as a whole were some kind of new and revolutionary technology - while it's a feat of miniaturisation and lovely engineering, some of the earliest computers (either mechanical or electromechanical) were specifically for gunnery. Firing an artillery or naval shell 20 miles requires some pretty complex (well, if you're in a firefight - it's not that hard but it's not "oh let me think about that a moment") maths to compensate for aerodynamic effects, spin, and the Coriolis effect. https://en.wikipedia.org/wiki/Rangekeeper https://en.wikipedia.org/wiki/Rangekeeper has a decent summary of the development of this tech.
- Bjartr 11y agoSpeaking of targeting computers, one of my favorite videos on YouTube is a training film describing the theory of operation behind a purely mechanical fire control computer by the US Navy circa 1953 https://youtu.be/s1i-dnAH9Y4 https://youtu.be/s1i-dnAH9Y4
- nsxwolf 11y agoThank you for that. I just watched a few minutes, but already, watching a cam compute a reciprocal is by far the most interesting thing I've seen all week. Analog computers were basically voodoo to me before this. Looking forward to watching the rest!
- bcoates 11y agoI love that film, but it's kind of weird that it doesn't mention what's probably the most important invention that makes this type of computer possible: The torque amplifier. All the devices shown suffer power losses between input and output, some of them severe. A torque amplifier has two shafts that are 1:1 geared for speed but the output shaft has extra power taken from a third supply shaft, like the supply to a logic gate that lets it drive more output power than it draws from its inputs. https://en.wikipedia.org/wiki/Torque_amplifier https://en.wikipedia.org/wiki/Torque_amplifier
- aswanson 11y agoThanks...just goes to show how brilliant some of our pre-digital forbears were. I still give more props to old school television engineers to present day ones. The laws of physics are far more unforgiving than the laws of a compiler.
- Mvandenbergh 11y agoSome more links on the electromechanical fire computers of the B-29: http://www.twinbeech.com/CFCsystem.htm http://www.twinbeech.com/CFCsystem.htm (scroll down for technical information from the user manual) http://www.glennsmuseum.com/bombsights/everything.html#B-29_Central_Fire_Control_Computer http://www.glennsmuseum.com/bombsights/everything.html#B-29_... (great pictures) http://web.mit.edu/STS.035/www/PDFs/Newell.pdf http://web.mit.edu/STS.035/www/PDFs/Newell.pdf A bonus link, review paper on WWII electromechanical fire control computers.
- Blackthorn 11y agoI was quite surprised to learn recently how the B-29 was (A) about as expensive a project as the atomic bomb and (B) almost a complete failure (until the firebombing of Japan) due to no one knowing about the jet stream.
- arethuza 11y agoI believe there was also the prospect that if the B-29 hadn't been available the atomic bombs would have to been dropped from the British Lancaster - which was the only other bomber capable of carrying them at the time.
- mikeash 11y agoDoesn't (A) count the cost of producing all 3,970 airplanes, not just the R&D cost? Seems a bit misleading to compare that to an R&D program that produced one test device and two bombs.
- walshemj 11y agoB29 was built to bomb Germany from the USA in case the UK had fallen.
- dandare 11y agoCan someone please explain how the gunner/computer established the range and speed of enemy aircraft? The article says "a gunner would focus a series of dots" but unless at least two gunners are focusing the same plane I have no idea how they calculated range and speed. Thanks.
- marktangotango 11y agoI used to be a gunner on an M1A1, and although we had laser range finders, we also practiced with the old style optical sights that were installed alongside the main gun. How range finding works with optical sites is you usually have a series of marks in the viewfinder that you use to physically measure what you're aiming at, so if the tank/plane/whatever is between particular two pips (or whatever; edit iirc the M1 had two curved lines you would placer over the target) you know that it's about x meters away. The pips are calculated knowing the average length of the object, so this is, in practice, close enough. The procedure is; measure the target, then use cross marks on the cross hairs to raise the gun tube to the appropriate level, manually guess lead and defilade, fire, on the way. It obviously takes practice to get good at. I found it curious that the US Army continued to teach/train/use this method, as well as land navigation with compass/mapp instead of gps. The idea is to not rely on technology entirely. Edit: turns out I am describing stadiametric rangefinding: https://en.wikipedia.org/wiki/Stadiametric_rangefinding https://en.wikipedia.org/wiki/Stadiametric_rangefinding
- kiiski 11y agoWhat military doesn't teach navigation with a compass? I would also imagine that most, if not all, teach rangefinding to those who might need it; snipers/sharpshooters, gunners, etc. My only military experience is from my compulsory service in the Finnish Defence Forces, where everyone does have to learn how to read maps and use a compass (we never used gps/other equivalent). I was in signals myself, so I didn't have any training for rangefinding.
- digi_owl 11y agoI seem to recall that the gunner on one of the more successful German tank crews during WW2 basically had the sights set for a specific distance and then eyeballed it from there.
- rplnt 11y agoThat "share on pinterest" feature sure is annoying when it blocks text.
- jessaustin 11y agoThis confirms for me a complaint I've always had about the Millennium Falcon. A ship equipped with hyperdrive would certainly have had targeting systems as good as a B-29. There would have been no need for the midships ladders to the gun stations.
- JoeAltmaier 11y agoBut the best part of old WWII movies were the dogfighting scenes. And the movie you reference was cribbed from there. So, poetic license.
- deleted 11y ago[deleted]
- fit2rule 11y agoUnless the ship was assembled from parts of different things from around the empire...
- enraged_camel 11y agoYeah, I think it was implied that the MF is heavily modified to significantly expand the capabilities of the base ship. So maybe the stock automated cannons were replaced by manual but more powerful versions. Or something. ¯\_(ツ)_/¯
- david-given 11y agoHaving blown up a tonne of them in Tie Fighter, the stock YT-1300 basically had all the fighting ability of a cabbage. The only real thing to be worried about was ramming them by accident, or possibly laughing too much to rebalance your shields. So yes, I'm pretty sure the Millenium Falcon was heavily upgraded.
- gherkin0 11y agoIf I remember that scene correctly, the gun stations on the Millennium Falcon seem more like the B-29 sighting stations than directly operated "local control" guns (but located directly behind the remote controlled gun rather than next to it). The biggest problem that I see is that this causes the MF's sighting station's FOV to be smaller than the one pictured in the B29. But yeah, that scene is mostly artistic license.
- Pyxl101 11y agoI had no idea that fire control computers in airplanes were so sophisticated in the 1940s. Truly amazing! I don't know what I thought, but I guess I assumed that air battles back then relied primarily on line-of-sight and tracers to compensate. It's amazing how effective automation can completely transform an activity and elevate it to a new plane of effectiveness. I'll channel Andreessen and say: technology is eating the world.
- etangent 11y agoOut of curiosity (and possibly a dumb question), what is the main constraint preventing modern (subsonic) bombers from carrying CIWS-type defense system against missiles? Is it size, weight, recoil, aerodynamics, or special radar requirements? The initial push behind removing gun systems appears to have been development of AA missiles and increased reliance on fighter escorts. Yet modern CIWS on sea vessels have become so effective against missiles that they significantly upped the cost and requirements of anti-ship warfare, to the point that a single missile fired at a ship is not expected to be successful. Given advanced enough CIWS (using directed energy in near future?) one basically doesn't need stealth or other fancy/expensive/less reliable features.
- ckozlowski 11y agoI'm just guessing here, but I'm going to bet that defensive ECM is probably deemed better effective per pound that CWIS. It's worth noting here that CWIS' effectiveness hasn't really been proven. But what is certain is that it's theoretical effectiveness is being questioned as missiles get faster. The original 20mm CWIS had a pretty limited range. The Europeans went to 30mm with Goalkeeper, and now both are set to be replaced with either directed energy weapons (faster tracking, better accuracy) or systems like SeaRAM, which can engage further by switching to point defense missiles instead of guns. I can see how directed energy weapons could be attractive to aircraft once the power density issues are solved, but right now they're simply too heavy.
- pippy 11y agoHow did they do this without transistors? The only thing I can find is this diagram here which looks like a small box: http://www.twinbeech.com/images/TURRETS/cfc/CFC%20computer197web.JPG http://www.twinbeech.com/images/TURRETS/cfc/CFC%20computer19... which is smaller than a vacuum tube. I'd assume you'd need vector calculus to calculate the path of a bullet?
- monknomo 11y agoThe first thing to keep in mind is that these are not general purpose machines. They only do one thing, which is estimate the trajectory of a particular type of bullet, given several inputs. This lets the designer do a lot of precalculation, so they might use a series of cams that approximate known curves or differentials some known ratio. Useful google terms are things like "mechanical fire control computer" or "mechanical tide predictor". Check out "Old Brass Brains" it might give you an idea of how to approach this kind of problem mechanically; or at least how sophisticated a mechanical approach can be.