November 24, 2023

Open Thread 144

It's time once again for our regular Open Thread. Talk about whatever you like, so long as it isn't Culture War.

Hope my American readers had a good Thanksgiving.

Overhauls are Iowa Part 4, Falklands Part 8, Missouri Part 3, The Navy and the Space Program, Falklands Part 19, Naval Bases from Space - San Diego, and for 2022, my review of Udvar-Hazy and The Case for the F-35.


  1. December 03, 2023muddywaters said...

    Why are guided shells such a recurring tried-and-abandoned idea??

    I can see why they might be a bad idea, compared to a rocket of similar size and guidance: it seems plausible that guided weapons mostly don't care about the advantages of shells over rockets, and do care about their disadvantages. A shell has to fit in the gun and survive the extreme acceleration of being fired, which are plausibly difficult for steering fins. Guns are heavy enough that you often only have one, limiting the rate of fire, while rockets can be fired from basically their storage box, allowing many to be fired at once. Shells probably have better unguided accuracy than rockets, but that's plausibly irrelevant when better is still bad enough that you're fitting guidance either way. Differences in the cost of the base projectile are less relevant when most of the total cost is the guidance system.

    However, if it were that obvious that they were a bad idea, it wouldn't make sense to waste money trying to make them. And several did try, from the 1940s to the present and from 57mm to 16". Some succeeded in making a working prototype, proving that it is possible, but decided not to put it into production, implying that it wasn't worth it even with the development costs already paid.

    Also, that reason would also apply to land forces, and those do have apparently successful guided shells. Possibly the key difference is that land combat is much more likely to take place at the short ranges where unguided shells are useful, and hence land forces have a higher ratio of guns to rocket launchers?? And since those are on separate vehicles and dispersed to make them harder for the enemy to find, replacing a few of each gun's shells with guided shells adds more flexibility than replacing some of the guns with rocket launchers?? While at sea, missiles are dominant enough that boats too small to have both pick the missile launcher, and heavy-ish guns only remain because proper ships are big enough to easily have both?

    The Zumwalt in particular feels vaguely like an attempt to satisfy political demands that the Iowas couldn't be fully retired until there was a replacement that could match 16"/50 performance, by building something that's technically a shell but practically closer to a missile, and hence super-high-performance for a shell but expensive enough that you're better off using real missiles.

    However, that doesn't explain all of them. Am I missing something that's obvious to those who know more?

  2. December 03, 2023John Schilling said...

    Guided shells in land combat are used in indirect fire just as was expected of the Zumwalt's guns. There's not much point in using them for direct fire because at direct-fire ranges a modern fire control system can put even a dumb round on target on the first shot. If you're firing a howitzer from 15 miles away, you want it to be shooting American GPS-guided "Excalibur" 155mm shells, or Russian laser-guided "Krasnopol" 152mm. Experience in Ukraine is that these work very well, but there's never enough to go around. Land warfare uses a lot of shells.

    Naval warfare, you're limited to the number of shells you can fit in the magazine, and given the cost of putting that magazine within reach of the enemy, they really ought to all be guided. And while there is some added complexity to achieving Excalibur-like performance from a naval platform, it really shouldn't be a problem.

    The problem is that the USN wouldn't consider using Army-type shells even as a "good enough" fallback option, and insisted on making the perfect the enemy of the good. And pretty much nobody but the USN has A: the budget and B: the warships to make it worthwhile to make the attempt.

    Italy, in their role as naval ordnance provider to non-US NATO, did come up with the the 76mm and 127mm "Vulcano" guided shells; these reportedly work pretty well but that may be shaded by marketing hype; they've been purchased only in small numbers and never used anywhere - probably because non-US NATO mostly only pretends to be capable of high-intensity warfighting.

  3. December 03, 2023bean said...

    I think a lot of the problem is organizational. Land-based artillery is important to a lot of people, and making it better is clearly a priority for them. But nobody cares that much about naval guns, because they're basically there to put shots across the bows of merchantmen and do a bit of light shore bombardment in a pinch. So if the program runs over budget, just cancel it. Zumwalt was a partial exception, but the issue there was that there were only a few ships and they showed up too late. There's also the issue that naval guns often have a secondary AA role, which often gets included in the list of things guided shells need to do. This makes them a lot harder to build.

  4. December 03, 2023muddywaters said...

    Possibly what I'm missing is just how often military projects in general are cancelled after they technically worked? (Either because they didn't work as well as the designers hoped, or because changed circumstances made them less useful.) So there's nothing mysterious here, it's just normal for a concept in the "might or might not be worth it" zone to have this many abandoned attempts?

    I think we basically agree on why they're more worth it on land: the more guns you have, the more it's worth improving their shells instead of switching to missiles.

  5. December 04, 2023Hugh Fisher said...

    I suggest the reason people kept trying guided shells at sea is because they're not obviously a bad idea.

    As a system a gun has a big, heavy, expensive "launcher" with small, cheap projectiles. A WW2 battleship would carry around a thousand main rounds, a cruiser a few thousand. Looks very attractive compared to the max hundred or so shots from a big modern warship. The guidance system pushes the shell cost up, but still cheaper than a missile - especially if you're thinking only of ship to ship combat, where you don't need to be as precise because a warship is a lot bigger than a tank or bunker.

  6. December 05, 2023muddywaters said...

    I'm not claiming they're an obviously bad idea, more being surprised to see that many technically-working but abandoned attempts, and apparently no successes. (Which I may have been wrong about: given the above, Vulcano may count as a success.)

    I'm mostly comparing them to the small missiles that would have similar performance and cost, not to big missiles.

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