October 04, 2019

Open Thread 36

It's time for our regular Open Thread, although it's a couple days earlier due to the recent ordering shuffle. Talk about anything you like, even if it's not naval/military related.

One of the main goals of my riverine warfare series is to form a framework for a more definitive history of the subject, because I have only seen one book that attempts a worldwide perspective on the matter, and it's a history of ships, not of operations. It also only goes back to the 1850s/1860s in most cases. The problem is that my knowledge before that is pretty limited, and this is a hard subject to look for. I'm sure that a lot of you are familiar with parts of history that I'm not, and can provide suggestions for where to go looking. I've already incorporated a few of these, such as Red Cliffs, but I could use more. Any suggestions for where to look?

Overhauled posts this time (list somewhat shortened by the change in dates) are the last three parts of the series on secondary armament and my review of Albacore, wrapping up my series on New England.

Comments

  1. October 04, 2019Lambert said...

    Came across this clip the other day: https://imgur.com/MyiDOMX

    As the jet age loomed, the RN decided that, with no propellors to collide with the deck, you could land aircraft on a giant inflatible crashmat. The RN added this to HMS Warrior in the late 40s and sucessfully landed a Sea Vampire this way.

  2. October 04, 2019Neal said...

    Wondering how those of you with Naval knowledge and interest would answer that old flight of fancy question if you had one modern weapon (nukes excluded) that you could employ on 1 January 1942 against both Germany and Japan what would it be?

    In the cockpit we usually played this game from the perspective from the Air Force. For example 1 F-16 with a LANTIRN pod and a KC-135 to refuel it. Take it downtown Berlin one night and then a few weeks later to Tokyo.

    I know it sounds a bit silly, but it does make one think a bit about exactly what you would want to strike.

    For the Navy would it be as simple as a sub with Tomahawks?

    The real question that all this gets to is how fast do you think you could effect a full surrender and a withdraw of forces to a status quo antebellum situation. Which weapon system would afford you the opportunity to end it with minimal effort as quickly as possible. Again, no ICBMs and/or tactical nukes.

    Thouggts?

  3. October 05, 2019Alexander said...

    Leaving aside questions of what counts as a weapon (a carrier group? A comprehensive history of the 20th century) I'm not sure how you'd defeat Germany with even a Ohio's worth of Tomahawks. What 154 coordinates end the war? With Japan sinking even a few dozen capital ships would give the allies sufficient naval superiority to hasten the end of the war, though probably not an immediate surrender.

  4. October 05, 2019Philistine said...

    @Neal,

    Why a fighter instead of a heavy bomber? A B-1, for instance? And instead of downtown Berlin and Tokyo (since both Germany and Japan proved extremely resilient to having vast swaths of their capitals bombed to ruin), how about a scenic tour of German and Japanese petroleum production and refining capabilities... with a few dozen guided bombs? Then, if losing their entire petroleum industries overnight fails to bring them to the table, you might make a return tour focusing on, say, electricity production.

    For a naval option... If a modern SSN with cruise missiles is in the mix, is a fully-loaded CVN fair game? Or would that be a bit too much?

  5. October 05, 2019ryan8518 said...

    Probably not the end of the world given the modern focus on GPS degraded targetting, but something to think about with bringing out a guided weapon to a time period with none of the GPS or really even the comms/reconaissance to take advantage of it. If I had to pick just a singular object to bring forward, it would probably be something like an AEHF satellite (or a Keyhole) over the Atlantic or Western Pacific, since we'll get a lot more mileage out of the improved comms capability than out of a relative handful of weapons (assuming we can figure out the ground stations problem). A nuclear attack sub would be an incredibly nasty individual platform if brought out on the Axis side, while I suspect an AWACS platform could be put to very good use by the allied forces. With WMD's off the table it's hard to come up with something that's enough of a force multiplier on its own for more than a single battle to convincingly change the course of the war. I'd really like to come up with something that would clearly affect the ground war in Russia, but I'm drawing a blank on a good idea for anything better than a modern long range/high mobility integrated artillery/radar unit.

  6. October 05, 2019bean said...

    I'm going to go with some B-52s and a bunch of LGBs. On a clear day, you can just loiter at high altitude, plinking targets. Nothing can touch you, and you get about two dozen bombs per sortie. Needs a lot less tanker support than a fighter, too. Probably none against Germany.

    @Lambert

    Flex deck is certainly interesting. One of the big issues was interoperability, because suddenly naval aircraft couldn't land on normal runways.

  7. October 05, 2019Neal said...

    Great answers as to be expected from this group as the responders understand that there is some thinking required about exactly what one is trying to do. Most people just jump in with the idea of just trying to decapitate those regimes without considering the vast expanse of territory they held.

    Whatever actions were taken, they had to be enough to make the regime leadership not only to cease kinetic operations, but also cede those territories and regions that they had conquered--a big ask to be sure.

    Philistine mentioned a B-1 and that would fit in well with Bean's suggestion of a loiter capable B-52 with PGMs. Perhaps much better than the LANTRIN equipped F-16 or F-15. I was lulled into thinking that this would all night and low visibility attack capability but the weapons payload would have been significantly less and required tanker support.

    I like Alexander's mulling of what 154 targets bring about the end state I mentioned. He made me think that combined with Bean's and Phillistine's suggestion of a multi-platform bomber that one could have, for example, gone heavily after the submarine pens and bases. This would have denied the Germans their second Happy Time of Jan to early summer of 1942 and have denied an entire theatre of operations.

    Ryan raises some really cool points and ones that I had never heard mentioned before. I like that what he puts forward is something that creates a comm infrastructure for further offensive actions across wide areas.

    Thanks for the replies. Well thought out suggestions. I appreciate the thinking.

    Btw...While I like imagining how it would be directly employed, like the tactical or strategic nukes I think a CVN would be putting a thumb too heavily on the scales for this scenario.

  8. October 05, 2019Alexander said...

    In addition to going after hardened targets, you might get some use of the Tomahawks as perfect pathfinders. If you want to level an industrial facility but don't have many missiles available then use just one and inform the first wave of bombers that there will be a large blast there at (say) 02:00 marking the location. I wonder if there was ever sufficient coordination with resistance forces that a blast or fire set by people on the ground was used like that.

  9. October 05, 2019Jade Nekotenshi said...

    I doubt this would actually be enough to bring the war to a close, but how much difference could a modern warship - say, a Ticonderoga or a Kirov - make in the Atlantic?

  10. October 05, 2019bean said...

    I'm very not sure you could use Tomahawk like that. It's a weapon that takes a lot of support infrastructure to use properly, and I think the framing of Neal's hypothetical denies us that sort of stuff. That's why I picked the B-52/LGB combination. You basically just need a map of the city with the targets marked on it, and can self-designate for the bombs.

    @Jade

    I presume you're talking ASW, right? It would make a massive difference. Having something which can detect any diesel boat on engines within several hundred miles and ping out to dozens suddenly means that so long as your torpedoes hold out, they're just dead, and so long as you have good comms with the conventional escorts, they're not getting very far.

  11. October 05, 2019Doctorpat said...

    One (1) laptop computer with a selection of modern decryption software packages.

    Probably want a couple of spare batteries and a selection of rechargers too.

  12. October 06, 2019Cyril said...

    Nerve gas

  13. October 06, 2019bean said...

    WMDs were ruled out of the original prompt. Also a bad idea. The Germans had the stuff, and using it would have lead to retaliation.

  14. October 06, 2019Lambert said...

    How does a modern strategic bomber with iron bombs stack up against what they had in WWII?

    Even without GNSS, do INS, automatic celestial navigation and digital bombsight computers improve accuracy much?

    I was just thinking about the case where 'and a bunch of LGBs' doesn't count as one thing.

  15. October 06, 2019Chris Bradshaw said...

    A modern surface combatant would also shut down any Focke-Wulf Fw 200 Condor sorties over the North Atlantic. Surface raiders like Bismarck would also have a really bad time, although I'm not sure if Tico's Harpoons could penetrate a Bismarck's armor belt and sink it outright. If the Harpoon dove into the superstructure, a mission kill is probable. Kirov's larger, faster, and more numerous P-700s are a better bet for outright sinking anything from WW2.

  16. October 06, 2019bean said...

    @Lambert

    It's better, but I don't know exactly how much better. The B-52s did a pretty good job over Hanoi in 1972, and technology has gotten better since then. That said, I think a reasonable number of weapons have to be included, or you're going to go with something like an Ohio.

    @Chris

    No way is a Harpoon penetrating Bismarck's belt. Frankly, I'd keep a ship like that as far away from any serious surface raiders as I could. The best use for it is as a force multiplier, providing more conventional forces with a vastly better view of the action, particularly under the sea and in the air. Way too valuable to risk against Bismarck. Kirov is a slightly different matter, obviously.

  17. October 06, 2019Chris Bradshaw said...

    Well as long as you stay out of Bismarck's gun range you shouldn't have any problems. Tico is faster and has infinitely better situational awareness, so just getting within Harpoon range, launching a salvo, and then bugging out should be fairly safe. Even if Harpoons can't sink her, they can at least destroy Bismarck's fire control center, rangefinder, radar, or secondary AA batteries, which makes the job easier for other Allied capital ships and aircraft.

  18. October 06, 2019Alexander said...

    What support do the Tomahawks need? Satellites for GPS or a link to the launch platform? Or some sort of data about the target that 1940s reconnaissance can't provide? I probably overestimated the capability of TERCOM and underestimated the difficulty of precisely locating the target.

    If you don't plan on fighting surface ships (and by 1942 Bismarck itself is on the bottom) I'd prefer an Izumo or similar to a Kirov, for the extra helicopters and a few decades less wear. You'd have to be careful in the Pacific though - people might get the wrong idea about the rising sun! I reckon an Ohio would be better still, because it's got the sensors to support the sub hunters, would be able to put any surface ship on the bottom (probably even when using whatever torpedoes the allies could build for it) can cover great distances at speed and I'd be surprised if they couldn't get some use out of the cruise missiles.

  19. October 06, 2019bean said...

    @Chris

    Things sometimes go wrong. I'd rather keep the Harpoons for self-defense, and let the conventional forces deal with it. (Note that Hood's loss was a fluke.) Not to mention that I'd probably have the Tico doing something else, like hunting submarines.

    @Alexander

    The big problem is that you need not only navigation data but also good georeferenced coordinates for the target. This looks easy today with Google Earth and such, but it's really not. I don't think you could do it without satellites. And TERCOM is not trivial to set up, either. During the time between Saddam's invasion of Kuwait and Desert Storm kicking off, the planners only managed to build a few TERCOM routes, one out of the Persian Gulf, another out of the Red Sea. Plus, a typical ship doesn't carry TERCOM planning systems, and you can't generate the data without satellites.

    A big part of the problem is that the scenario is seriously underspecified. The modern military requires a lot of support infrastructure, and how much comes through is a serious question. As is how much ordnance we get. B-52s with LGBs optimizes for low infrastructure (in terms of mission planning and such, not spares and maintenance) and needs extra weapons but if you get no extra weapons, you're probably best off with something like a Tico.

  20. October 06, 2019Alexander said...

    I remember your posts on strike warfare explaining that it is complicated, but I didn't quite grasp how much so, or how interconnected everything is.

  21. October 06, 2019Lambert said...

    I daresay with a B-52 full of smart bombs, you could destroy every bridge over the Rhein from Strasbourg to the North Sea in a single night.

    Go back a few days later to sink any freight vessel you see and you've cut Western Europe in half, logistically.

    Do similar with alpine passes, rail tunnels and the Danube downstream of Ingolstadt.

  22. October 06, 2019Neal said...

    I like the thinking here. The scenario is purposely left pretty open to see how one wrestles with real or imagined constraints. One can crank or loosen those constraints to reveal options. Bean did intuit that I wanted limits in this round so as not to lard on layers of infrastructure. He was correct in interpreting this as more or less a single weapons platform and the decision required as to where and how to employ it.

    Perhaps not surprisingly when the scenario is cranked all the way down to just a single airframe or vessel, a lot of Navy pilots used to tell me that they would have wanted a P-3 in order to put a stop to the German submarine threat both in the Atlantic but the Med and Baltic as well.

    As far as a laptop and encrypted messaging goes what a time saver that would have been for secure comms. The effort to encrypt and decrypt even basic messaging back then seemed like an exercise in practice bleeding.

  23. October 06, 2019bean said...

    I'm not actually sure that a P-3 would have been a good choice there. MPAs usually require queuing against submerged submarines by something like SOSUS, which is actually not a bad choice if you want to win in the Atlantic, but it's also way too much to bring back as an adjunct to the P-3. Against surfaced submarines, it doesn't have any serious advantages, and it trades a lot in versatility when matched against the B-52/LGB combination or something of that nature.

  24. October 07, 2019Lambert said...

    Now I understand why bomb units are so modular.

    Turns out a Mk80 series will accept both a Quickfire naval mine conversion kit and a JDAM kit.

    If you can get it to work with an LJDAM or Paveway, then our anachronistic bombardiers get to precision-mine Europe's vital inland waterways and ports.

  25. October 07, 2019bean said...

    The big advantages of precision mining are standoff and the precise knowledge of where the thing is so you can clean it up after the war. We care a lot more about the second than they used to, and area defense weapons weren't what they are now.

  26. October 07, 2019John Schilling said...

    "What support do the Tomahawks need? Satellites for GPS or a link to the launch platform?"

    Skip the Tomahawks, and the B-52 and the LGBs and all that, and send the satellites. Or, per the rules, just one satellite. I'll refrain from speculating as to exactly which one on account of reasons, but there are several delightful options to choose from.

    The allied powers in WWII had demonstrably sufficient aerial bombardment capabilities, but their overhead reconnaissance was usually insufficient even to tell them whether they had actually blown up what they had already decided was worth aerially bombarding. Also, they kept getting surprised by surprise attacks. Enough with that already.

  27. October 07, 2019Directrix Gazer said...

    I like Bean's B-52 with LGBs, but a question occurred to me: are there any runways in 1942 that can handle it? Otherwise it's a single-shot weapon. I suppose this need for greater support facilities is a key weakness of an aircraft vice a naval platform for the posited scenario.

  28. October 07, 2019BakerEasy said...

    I think B-52-grade runways are within 1942 capabilities, if not actually built. But say you get two runways along with it, one in Europe, one in the Pacific. Where do you put them? IIRC there was a plan to base B-29s in Northern Ireland (to give them more time to climb to altitude); that may be a plausible site for BUFF Base One. The safe choice for BUFF Base Two is probably Midway; Honolulu is even more secure but puts parts of Japan at the edge of the B-52's reach. For an aggressive option, I'd suggest Davao - is one B-52 enough to break the siege of Bataan? If so, the whole of Japan and SEA are within easy reach from there.

  29. October 07, 2019Lambert said...

    Looking at the operational ranges, you could get away with a single base in Pakistan, so long as the Himalayas don't mess things up. It would cover all of Europe, Japan, China and Mainland SEA. (Alex Wellerstein's MissileMap is a good tool for this.)

  30. October 07, 2019Philistine said...

    The obvious choice for the Pacific runway is Guam. But since that won't be available, Darwin might be a good second option: it's a long flight from there to the Home Islands, but well placed for cutting off the Southern Resource Area.

    The various proposals for Final Countdown-ing various communications and intelligence assets are great, and would give the Allied forces significant advantages in basically fighting WW2 somewhat better than as in @. But that seems to me to be a bit beside the main point of the OP, which was to force the Axis powers to surrender as quickly as possible and with as little effort as possible. To me, that says we do NOT want to (for example) re-fight the Battle of the Atlantic - Only Better! It says to me that we're looking for a lever long enough to shift two very aggressive and irrational regimes from "Yeah! We're totally winning this thing!" to "Time to get out while the getting is good!" virtually (or actually) overnight. That's why the ideas started with decapitation strikes, and targeting critical industries. If you're proposing sending back tech that would have a huge effect, but only over months or years, I'd love to read WHY that's the fastest and most efficient way to speed the end of the war.

  31. October 07, 2019Alsadius said...

    For the naval side, an attack sub seems the obvious choice. Load up with as many modern torpedoes as you can, use them to KO the bulk of the Japanese capital fleet, and then once they're expended, spend the rest of the war vectoring ASW forces against the U-boats in the Atlantic. Maybe save a couple to kill an Italian capital ship or two, and clear the Med a bit. You've basically won the naval war at a stroke(well, within a few months), even before you consider the psychological impact. I doubt Japan or Germany would give up immediately, given their psychology at the time and the fact that they were both doing well on land, but naval forces can almost never force an immediate decision on land.

    On the air side, whichever heavy bomber has the best payload, though I'll bias towards stealthy ones given the choice (since the Germans weren't dumb, and could probably come up with a countermeasure at 60,000 feet given time). A quick glance suggests the B-1B has the best load of the US fleet, and definitely enough stealth for the 1940s. Toss a few bombs at leadership, then use the rest on strategic resources of various sorts. Immobilize the German oil supply, and the war gets vastly easier. That said, that approach really helps Stalin, so maybe you want to use it for recon primarily until you're ready to launch Normandy. Then cut Europe in half like some of the other proposals, and get a much better advance than you'd otherwise be able to.

  32. October 08, 2019Alsadius said...

    As a side note, the reason I picked the sub above is that modern carriers seem poorly equipped to deal with armoured capital ships. They're designed for modern targets, not 12" armoured belts. If I'm wrong about this, and a modern carrier can do for battleships fairly reliably, then I'll take the carrier. (Even without escorts.)

  33. October 08, 2019bean said...

    Modern carriers aren't really optimized to kill battleships, but that doesn't mean they'd be totally useless. WWII air defenses are bad enough you can do all sorts of stuff that would be way too dangerous to pull off today. The best option is probably to take a BLU-109, fit it with a Paveway kit and a good delay fuze, and land it on one of the battleship's turrets. I'd give at least 50/50 odds of setting off the turret's magazine with a single hit. If that won't work (I don't really know how a BLU-109 will do against steel), you use the carrier as an enabler for other forces. Hit the battleship with a bomb on each director and another few at the stern to hopefully muck up the rudder and screws. This is utterly trivial for modern aircraft, and makes it a lot easier for, say, a destroyer squadron to go in and sink the thing with torpedoes.

  34. October 09, 2019Jade Nekotenshi said...

    Y'know, it strikes me that if I'm picking a surface warship, I'd take Kirov over Tico because she's got 53cm torpedoes. Those can definitely do in a BB or an armored CV easily in a pinch, and with guidance, are a lot deadlier than the period-correct torps would be.

  35. October 09, 2019Blow Stuff Up said...

    The obvious choice for the Pacific runway is Guam. But since that won't be available, Darwin might be a good second option: it's a long flight from there to the Home Islands, but well placed for cutting off the Southern Resource Area.

    Darwin is a bad idea since it'd be within range of Japanese bombers, proven by actually being bombed during WWII and the same applies to Northern Ireland as Europe base.

    A super weapon like that especially if an Axis power learns you've only got one is going to attract bombers so you really want to keep it out of reach.

    For Europe: The B52 would probably have the range that it could be based in the Northeastern US which puts it well out of reach of Germany, maybe Eastern Canada or Newfoundland if that'd be too far.

    For the Pacific: Mt. Isa might provide the best combination of closeness to targets and farawayness from Japanese bombers.

    The idea of a single base in Muslim India (Pakistan doesn't exist then) is appealing but it's also going to be a logistical nightmare to supply fuel, (crappy WWII era) bombs and whatever spare parts can be made using the tech of the time.

    I could see US sonar being better than what Russia has which would argue strongly towards a Tico and as bean said, something like that would be much more useful as a sensor platform than a fighting ship.

    Also remember that the anti-submarine helicopter carries homing torpedoes which could mission kill a battleship if they're aimed well, fire at the stern and an acoustic homing torpedo might head straight for the screws.

    The biggest problem is that the really good ammo isn't something that you'll get resupplied with as it can't be made with that tech so you use the crap they can build but with the better sensors and navigation wherever you can.

    That raises the question of how much of a technological jump they'd get from looking at future stuff, maybe pulling whatever comes back apart would help even more than actually using it.

    On targets: Blow up the factories making U-boat batteries, even if you can't bring back a history book with information on where everything is the allies at least know of the largest factory.

  36. October 09, 2019ADifferentAnonymous said...

    As far as winning the war at sea, I'm tempted to just ask for lots of Mk 48 torpedoes. (I'm assuming they'd be compatible with the tubes of era ships and subs, being the same diameter and shorter than US WWII torpedoes)

    Even assuming you can't use the wire guidance at all*, you have a full-power torpedo that can hit enemies from outside gun range as long as you can roughly predict their course. Seems especially devastating to an enemy who hasn't seen them before, so make sure to arrange a kantai kessen for the big unveiling. Once the enemy figures out the basic capabilities--long range torpedo with autonomous terminal homing--you won't be able to sink whole fleets without losses, but they'll find it hard to make much use of the sea when their battleships have to run away from destroyers.

    • I don't know anything about the electronics of this, but if the interface requires a digital computer that's probably not happening. If you could rig a way to send commands, you'd be constrained by the quality of your plots to know what commands to send, but I suspect the allies could come up with a system capable of getting significant value out of it.
  37. October 09, 2019ec429 said...

    Not sure it's really in the spirit of the question, but: One pistol. Along with instructions to shoot Admiral King* with it.

    • or insert your least favourite commander / obstructive bureaucrat / damnfool inventor whose harebrained ideas get good men killed, etc.
  38. October 09, 2019bean said...

    I've occasionally flirted with the idea that the actual best answer is a submarine tender or something of the type because it's going to give the best boost to native tech.

    Re Kirov vs Tico, I'm weakly on Team Kirov. The P-700 would be pretty effective against armored ships, and the differences in sensor capability won't be huge relative to the advantage it provides. Not to mention the nuke plant, which helps logistics. And there are some systems they could probably resupply, like the anti-submarine mortar.

  39. October 09, 2019cassander said...

    @bean

    Your modern carrier is going to have a fair number of helos with ASW torpedoes. Not ideal for sinking battleships, but I assume the torpedoes could be made to home on one, and they aren't all that much slower than torpedo bombers.

    @Alsadius

    This sounds like the right answer to me. The Nautilus was able to run rings around 50s era ASW practices, with a sonar that basically didn't work, a non-streamlined hull, and no experience operating at those speeds.

    A single modern attack submarine with a well trained crew would be absolutely devastating to any fleet of the era. They'd have no way to find it and virtually no way to kill it.

  40. October 09, 2019Chuck said...

    I think the real key is that whatever is chosen the focus should be informational rather than physical. An Arleigh Burke is not the best choice to go toe-to-toe with a BB, but it could keep track of it with impunity and kill u-boats pretty much as fast as it can steam from one to the next simply because of advanced sonar. Likewise an AWACS could essentially have taken the place of the entire British radar network, and had the added benefit of being used later to monitor the offensive air war as well.

    The problem with picking pointy bits is that as much damage as you may do, the combatants in WW2 were using relatively robust systems and had a vast capacity for repair. An excellent comment by Cassander way back in Open Thread 1 aptly points out one of the biggest issues in WW1 was the lack of overland logistics to exploit openings. 200 pinpoint strikes* could possibly set the Germans back a month, but that only gives you a relatively small window for your WW2 era army to capitalize on. Picking information instead of weapons allows existing forces to be used more efficiently, or lets you respond to threats that otherwise aren’t engageable.

    *Also keep in mind you are would be planning those strikes with WW2 era intel. Being able to hit a 20m target isn’t much use if you don’t know what town the target is in, much less have accurate coordinates.

  41. October 09, 2019Lambert said...

    I wonder whether you could do GNSS with modern satellites but WWII-era recievers.

    Maybe have each satellite broadcast a chirp in sync with each other. Mixing the various signals against each other at the reciever will let you calculate the difference in TOF between them. Either get humans to do the maths or set up some basic analogue circuitry to let you know when you're near a preprogrammed location.

  42. October 09, 2019John Schilling said...

    "But that seems to me to be a bit beside the main point of the OP, which was to force the Axis powers to surrender as quickly as possible and with as little effort as possible"

    So, a satellite optimized for oceanic surveillance. Then, once a day every day we send Tokyo a message with, A: the exact location of every Japanese warship and B: today's surrender terms, getting a little bit worse every day.

    Germany will be a bit harder, because there's more latitude for keeping things hidden on land and it will be harder to convince them that they are hopelessly outclassed. But convincing Japan to stand down would I think go a long way here. Or maybe we just wind up starting a war between the Imperial Japanese Navy and the Imperial Japanese Army.

  43. October 09, 2019Neal said...

    @John

    I like your thinking with you last post and one that very much is in the spirit of the original scenario. Your two step approach allows us to gain a staggering amount of Intel on Japananese force configuration and deployment.

    Step two is to have a chat the the opposing representatives and give them what amounts to a fait accompli. Should they demure, then the jiffy quick despatchement (destruction in other words) of some of those aforementioned deployed and hostile forces would foster at least some minds to be changed.

    This nicely slides into "we know where the targets and we can depatch them quickly and with ease so let's chat again.

  44. October 10, 2019cassander said...

    @john & Neal

    I think that a 30kt submarine hanging out outside Truk sinking one ship a day would have a greater effect.

    Less tongue in cheek, I'm not sure how much better information buys you. The allies already had a substantial intelligence lead. Modern intelligence systems would, of course, be vastly better, but that would be to the most in the early stages of the war when the allies were still on the back foot. It would still needed to be ended by long and brutal exhaustion of the Axis.

    Other than nuclear weapons, there aren't many other single technologies that could dramatically accelerate the process. Something that can sink any Japanese task force, however, is one of the few things that could. I think you could cut at least a year a year off the pacific war by radically accelerating the a lot of the early blow trading while preserving more US assets.

  45. October 10, 2019bean said...

    I feel compelled to point out that satellite ocean surveillance is still a hard problem. Even the best single-satellite systems can't really combine good resolution with wide coverage. I'd suggest a photographic recon satellite is your most valuable option if you go for a space system. You can't effectively go after ships at sea, but ships spend a lot of their time in port, particularly when they're short on oil. And you will know when they sortie, so long as there are no clouds.

  46. October 10, 2019John Schilling said...

    I unfortunately have to be extremely vague as to exactly which satellite I would want to send back to 1942 and with what mix of optical, radar, and SIGINT capabilities. And I'm not even necessarily limiting it to US satellites(*). But I'm pretty sure we can have Yamamoto breaking out his brown pants.

    And from a metafictional standpoint, suspension of disbelief is probably easier to manage for a satellite than a warship or airplane; just handwave something about a passing wormhole or being caught in the wake of the starship Enterprise on one of her once-per-season visits to Earth's historic past. Or maybe Planet Express Ship; those guys are much less careful with the space-time continuum.

    Hmm, if we go that route, I have to start thinking about what sort of last-minute software patch we send to the satellite to have it signal the boffins at MIT that it exists and how to establish communications with reasonable bandwidth. Tricky.

    • Fortunately all of the plausible candidates are run by people with serious grudges against 1942-Japan.
  47. October 11, 2019ec429 said...

    @Lambert: Dealing with the ephemerides (motion of the satellite) will make it a bit tricky, but the basic principle of multilateration/TDOA ranging was definitely in use by 1942 for bomber navigation. Two examples were the British GEE and OBOE systems.

    OBOE was a fairly straightforward extension of the kind of range-and-bearing systems that were already around (such as the Wotan II (aka Y-Gerät)). Those combined a directional radio 'beam' (often produced by the Lorenz system) with a transponder in the aircraft to measure round-trip time (via the phase delay in the modulation). OBOE however did not involve a beam, instead applying the same range-measuring transponder with two ground stations (rather than just one). The aircraft (typically a Mosquito, thanks to the type's high ceiling altitude maximising the range of the VHF signals) would fly on a circular arc centred on one station, until its range from the other station reached the proper value. OBOE was very accurate, but as a transponder system had the problem that only one aircraft at a time could use it (as a result it was mainly used to drop Pathfinder flares to mark targets for the heavy bombers).

    GEE, however, was in a sense much more sophisticated: as a hyperbolic navigation system it had much in common with today's GPS. A pulse would be sent by one ground station, and received and re-radiated (with a known electrical delay) by two others. The receiver on board the aircraft would be used to measure the time delay between the 'master' and 'slave' pulses, which could then be looked up on a chart (map) with intersecting hyperbolae (the locus of points with a given difference in distance from two reference points is a hyperbola) to find the aircraft's position. As a passive system GEE could be used simultaneously by arbitrarily many receivers, and allowed the aircraft to maintain radio silence; but it was rather less accurate than OBOE, and was susceptible to jamming.

    Later, in 1943, a further system named GEE-H was developed. This used modified GEE equipment to implement a variation on the OBOE principle, as a reverse transponder system. Instead of the ground station interrogating the aircraft as in OBOE, the GEE-H unit on board the aircraft would send out the initial pulse, to which each ground station would reply. The aircraft could then use the time delay of each signal to determine ranges and calculate its position. The clever part was that each aircraft used a slightly different pulse repetition rate, so that many (in practice about 70-80) could use a station at the same time, and see only their own replies.

    So, could 1942 engineers have built a GPS receiver? Well, no; CDMA is probably beyond them, as is calculating the 4-D solution (intersection of hyperboloids of revolution) from the ephemerides on-the-fly. But, if we are allowed to reprogram the satellite before we send it back, then we can probably come up with something that can usefully be received with GEE-level technology — though it's an open question how much more accurate the resulting navigation would be than GEE itself. We'd almost certainly need the satellites to maintain circular orbits, and we'd want to obtain fixes from triples of satellites in the same orbital plane, as that hugely simplifies the calculations — you can keep the angular separation constant, and thus have a set of grid charts for that separation that only needs to be offset to account for the mean anomaly.

    One advantage this system would have over GEE is that the intersection angle of the signals could be much greater; it is this angle that determines the accuracy of hyperbolic navigation for a given accuracy of timing measurement. Also, of course, it would still work when outside line-of-sight of friendly territory; and the signals coming from above should be somewhat distinguishable from jamming coming from below.

  48. October 11, 2019bean said...

    I'm very not sure you could do something like GEE on 1942 tech. The satellite is moving, and there's no good way to compensate for that in electronics of the day. You'd be much more likely to build something useful based on Transit, the original satellite navigation system. It used the doppler shift of a single satellite pass to work out location, somewhat less accurately than GPS, but still a big improvement over LORAN and other similar systems. And it was developed in the late 50s, so you only have 15 years of electronics to make up.

    Of course, LORAN (another hyperbolic system) is the fly in the ointment of all of this. It was actually available late in WWII, covered most of the world, and could do the gross navigation tasks we today associate somewhat with GPS. You can't drop bombs with it, but you can make sure you're dropping on the right city.

    @John

    We could probably even make that patch give it some store-and-forward comsat capability. But yeah, I suspect that communications is going to be the big bottleneck with that one.

  49. October 12, 2019Lambert said...

    So doppler probably flummoxes everything involving space.
    But I bet you could improve on gee if you have modern transmitters on the ground synchronised using atomic clocks and the like.
    Get one ground station to do a linear chirp from 100-101MHz 100 times a second and another to chirp from 105-106MHz at exactly the same time. Have the aircraft recive each signal and mix them together.
    If they're equidistant, you'll get out a signal of exactly 5MHz. Deviation from 5MHz will tell you exactly how much further from one station you are compared to the other. No mucking around with local valve oscillators.

    On a somewhat different tack, how about we give the Allies modern global weather forecasting tech?

  50. October 12, 2019Neal said...

    @Lambert

    "On a somewhat different tack, how about we give the Allies modern global weather forecasting tech?"

    Indeed. Even just accurate winds aloft would have been of a valuable first step.

  51. October 13, 2019quanticle said...

    The problem with modern weather forecasting tech is that it relies on a comprehensive network of ground stations and satellites to supply it with data. Without that data, you can have the most powerful supercomputer in the world and all you'll get is garbage-in-garbage-out.

  52. October 13, 2019Lambert said...

    I mean to include weather sats and ground stations throughout the Allied world.

  53. October 15, 2019bean said...

    Does anybody have a good link for the "Argentina sunk Invincible" theory? I mean an argument in favor of it, just to prove that such people exist in an upcoming post. At least on the Anglophone internet, I usually find a OP written in broken English with the credibility of a flat-earth conspiracy theorist.

  54. October 15, 2019Daib said...

    Wait, people believe that?

    Another completely random question: Can anyone ID the warship that appears in the Dr.Doolittle trailer? It looks vaguely French, but I can't place it.

    https://youtu.be/FEf412bSPLs?t=67

  55. October 15, 2019bean said...

    Apparently, a lot of people in Argentina do. I can't really blame the pilots who attacked Avenger. They were flying single-seat jets at extreme low level in dubious weather and half of their number were downed by British fire. But the confusion should have lasted a couple days, not 35 years.

  56. October 15, 2019Chuck said...

    @Dalib

    It looks like it is based on the Russian battleship Tsesarevich, which was French built. It has some elements of the French battleship Jauréguiberry (which the Tsesarevich was based on), so I think it’s probably a mashup of the two.

  57. October 16, 2019Chuck said...

    @bean

    thanks for fixing my butchered href tag!

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