Saturday, February 29, 2020

Postblogging Technology, November 1949, II: Atom Bombs, Radars and GREEN MACE

In November of 1949 we saw a bit of an "AA" renaissance. Wartime AA chief, Lieutenant General Sir Frederick Pile (Bart)'s book-length version of his war's end communique, Ack-Ack; and American technocrat Vannevar Bush's Modern Arms and Free Men manage to make it into the back pages (sort of) of the periodicals we follow.

Our apologies to whatever second-rate archaeological dreck or wartime reminiscence that Time and Flight, respectively, would otherwise have covered. Thanks to that forebearance, we know that Pile was robustly enthusiastic about AA in the new nuclear age, whilst Vannevar Bush thought that it was actually now possible to defend against the nuclear terror weapon. While we're a long way from the Reagan-era high flowering of Star Wars, that day is perhaps peeping over the horizon. 

So it seems like a good week to stop and contemplate ABM, a sort of recurrent fever or  species of social contagion, not entirely unlike other moral and other panics that periodically infect us. 

This isn't to say that such things are entirely futile. Runaway cold virii sell a lot of garlic, ginger and onions, the green grocer knows, and vast schemes of antiballistic defence may produce electronic (and other) spin-offs.

GREEN MACE: By Tony Symonds - Symonds Family Archive, CC BY 4.0,
Have I mentioned Memex? Everyone mentions Memex. Thanks a lot, Charles Stross!
Another of those incredibly cool RAINBOW CODE products of the old Ministry of Supply, GREEN MACE was an automatically-fed mobile 5" AA gun firing fin-stabilised discarding sabot ammunition at a rate of 96 rounds  a minute from 14 round drums. Although the prototype was "only" in 102mm calibre. Considering how big a 4" round is, this all seems a bit mechanically staggering and might call for a discussion of all that "mechanical handling" stuff we're seeing in the engineering literature, but I have enough on my plate for this post as it is. There was apparently a bit paper on the question in the Proceedings of the Institution of Mechanical Engineers in 1962 that I'm going to look at this afternoon, but after some reflection, I've decided that it can be left out of this post, as radar is a fuck of a lot more important.

GREEN MACE seems to have made its first appearance in 1954, was delivered to the Royal Artillery in '56, put through its paces, and then stored away in what looks like an abandoned garage out back the Woolwich barracks forever after, because it is fairly pointless. There is no discussion of the director or radar attached to the gun, but, as I edit, I am here to report that I eventually got on with it. As far as Wikipedia, the grognards and the display card are concerned, it just showed up one fine day in 1956 (or 1954). But that doesn't mean that we can't reconstruct it, insofar as it is worth reconstructing. 

AA Command got its start a ways back in WWI, and became a political football in the run up to WWII as Winston Churchill's son-in-law, Duncan Sandys, ignited a controversy over it not having as many guns as it needed, and it all being Neville Chamberlain's fault. I've touched on this before, as Sandys used a secret(?) instant-developing camera to take pictures of secret(!) documents at AA headquarters, and it all went sideways when he loaned it to his girlfriend to take some louche pictures, showing that for all the suggestions of nepotism in his rise, the man really did have some ability to grasp what a given technology is really for. At the time I was mainly concerned in pursuing the existence of a polaroid camera a decade before Edward Landis invented them, but there's only so far you can go there without becoming some kind of hobbyist nerd, so I'll leave a self-link and be done. 

The Sandys controversy had mainly to do with AA Command's desire for an entirely or mostly mobile force. In heavy AA parlance, that's a gun that fires from a travelling carriage, as opposed to a "static" gun that has to be winched in and out of a built foundation from its travelling platform. While both are mobile, and the "static" gun is more effective, because there's the whole planet to absorb its vibrations and not just wheels and trail, only mobile guns move fast enough to catch up with an enemy air force as it shifts between targets to disperse defensive efforts. (A practice that causes the giant-brained "Nuh-unh bombers" crowd to accuse air forces of doing strategy wrong, but I digress.)

In any event, reality intruded on the pre-1939 War Office's utopian fantasies, in this as in other matters, and most of AA Command's guns were static. A discussion can be found in the early chapters of the official history before it peters out into mostly boredom, because AAA just is boring. (An hundred pounds the copy. Holy crap!)

Well, except for the technology part, where AA Command soon realised that their 3.7" AA lacked performance at altitude and borrowed the Navy's 4.5" and later 5.25" AA guns, which fired heavier guns with more momentum to reach up to the German stratospheric bombers that never came, and the recon Ju86Ps that did. The 5.25"s, in particular, were installed right in Navy style turrets, which introduced the army to the Navy's interests in automatic loading, but also directors and radar and automatic direction. All of this had ended up a bit of a balls-up on shipboard, but with a turret of their own to play with, the army proceeded to crawl all over the Navy's stuff. It is not exactly clear how this ended, perhaps because at the end of the war, the engineers all went off to design wiredrawing machines Now New and Improved with Back Pull. The main point is that the engineering innovations (translation: "crazy-assed shit") that went into GREEN MACE were already being tested on the bench back in WWII. 

This brings us to the bit where AA Command briefly stopped being boring, which was when the German V-weapons showed up. The V-1 is moderately famous as the German "vengeance weapon" that could have worked, and AA Command gets due credit for the Divers Belt that shot down so many of them, in no small part due to American radars and directors guiding tachymetric-stabilised and power-driven AA installations, leading to much writing about "cybernetics" in the postwar era, including in one of my first posts, way back when. The Command's success led to Sir Frederick proposing to do the same to V2s, which, since they plummet from semi-orbital altitudes at hypersonic velocities, is something of a different kettle of fish. 

I feel like I'm being trolled here.
Freddie's wander into Strangelovian territory is pretty well known, because it was hilarious. A proposal that worked out to firing  320,000 3.7" rounds across the path of a descending V2 crossed the desk of the committee (CROSSBOW) tasked with  V2 defence, and given an estimated dud rate of 2%, never mind shrapnel, so obviously amounted to a proposal to level a property with shelling in order to save it from missiles, that everyone had a good laugh and saved it for posterity. 

Nothing daunted, fortunately on the spin-off front, Pile came back with a proposal involving an improved fuze (to reduce the dud rate) and a closer analysis that suggested firing 150 shells per rocket to give a 2% kill rate. The Wikipedia article I'm still quoting from says that members Roderick Hill and Charles Drummond Ellis liked the proposal. 

Having some supporters on the committee allowed Pile's proposal to advance to some kind of independent feasibility study. It would be interesting to know just how that happened. While crazier ideas have percolated to the surface in wartime, a quick scan of the biographies of the two men suggest unhappy relegation to the committee, and leave me wondering whether CROSSBOW might have had lower priority than the situation would seem to warrant. Ellis was a scientific mandarin, having been exiled from the Cavendish to White Hall for the crime of failing to realise that he was looking at neutrinos in time to win another Nobel for Cool Britannia. Hill, meanwhile, had a reputation for being one of the cleverer technicians amongst the air officering set. If I'm not misremembering, he had a hand in the Westland Pterodactyl? Perhaps gun-based ABM suggested itself as a way back to the corridors of power for both men. If so, it didn't work, as they remained relegated to the outer darkness of academic administration and tobacco advocacy postwar, respectively. Even the final draft of the "plan" allocated 60,000 shells per missile; which seems to me to be accomplishing what I would have thought would be impossible; To wit, losing a strategic war of economic attrition to the V2.

Given the larger burst radius and higher velocity, GREEN MACE is perhaps a solution to the whole "60,000 is a lot of shells" problem, even if the more obvious use for it was to shoot down individual commie pinko nuclear bombers coming in at B-29 altitudes. We don't know as much as we'd like about postwar AA Command plans --a source on the Internet seriously cites the archaeologists of English Heritage about changes in battery layouts in the mid-Fifties, since evidently the rationale was inaccessible to the writer. This leads one to wonder if English Heritage has an explanation, and --ta-da!  It turns out that the grognards don't know as much as they think. The link is to a description of the Halls Green Farm site, completed in 1949--50 as part of the IGLOO line, intended to take 4 3.7" guns, but the introductory material notes that more elaborate battery sites for 5.25" guns also existed, and that these had automated loading systems. 

Now I'm regretting not hauling my ass out to the library this sunny afternoon. Oh, well, procrastination is king, and the radar is a lot more important here.  The official history of the British strategic deterrent has an entire chapter on ABM, and manages to get through 1949/50 and the publication of Ack-Ack with a single reference to Henry Tizard demolishing a proposal for a new radar that would detect boost phase Russian missiles with the comment that there existed no practical means of shooting them down. While Matthew Jones has a great deal of ground to cover in this chapter, as it turns out that the ABM effort was intimately involved in the effort to develop penetration aids for BLUE STREAK and to motivate BLUE KNIGHT as providing a re-entry vehicle to practice on, this is giving some things short shrift. The urban exploring site, Subterranea Britannica, of all places, puts me on the right track, discussing the proposed control suite for the new IGLOO sites, comprised of a new director, the Predictor No. 11, a tactical radar (YELLOW RIVER) and an operational radar, ORANGE YEOMAN, with a range of 90km and a maximum elevation of 60,000ft. Obviously not a boost-phase detection system, given how impractical that is in the context of 1949, I might be overinterpreting here. ORANGE YEOMAN went on to be trialled by AA Command before being handed over to the RAF on the Command's stand down, and became the AMES Type 82 tactical control radar for Bloodhound Stage 1, and was intended for the VIOLET FRIEND ABM missile system.

As this is something that I literally just learned about right now, we're going to take a bit of a swerve here. VIOLET FRIEND employed BLUE YEOMAN (someone isn't paying enough attention to how the colour code system is supposed to work) radar, later AMES 85, following from BLUE RIBAND, a monster radar designed to burn through EW jamming, itself a development of GREEN GARLIC, at which point I have successfully backtracked my way through Wikipedia to the kind of systems that Tizard was on about.

It turns out that GREEN GARLIC was an experimental radar set, developed at the RAF's TRE in 1949 when IGLOO and ROTOR were coming together. Meanwhile,  the Army's RRDE and the Admiralty's ASE were perhaps more loyal to the initial brief, which was to upgrade the wartime Chain Home with a powerful, comprehensive "microwave early warning" radar. Reading between the lines, perhaps including things that aren't actually there, ORANGE YEOMAN was the Army's choice, while ASE was developing what became the Type 984 3D radar for the Navy.  

So, is there, in the summer of 1949, a fight going on between proponents of "MEW" and the new GREEN GARLIC? Tizard doesn't seem like the guy to be fighting in the bureaucratic trenches against this wonderful lashup of a shiny new 2 MW magnetron and the engineering required to support same, but Type 984 frankly sounds even cooler.  
"Revolt of the Admirals" more like "Revolt
of the assholes," amirite?

Meanwhile, it looks like the cousins were quite taken by all of this, because Bendix, GE and Bell Lab materialised a similar radar in time for the 1951 bomb tests at Eniwetok, the AN/FPS-20. Given the timing, it sure seems like the prospect of GREEN GARLIC galvanised activity on the American side of the Atlantic, where there was admittedly more than enough going on with the recent initiative to build a radar system capable of catching incoming B-36s --or at least demonstrate that such a thing was practical, in order to collect an Air Force bomber scalp for the Navy. We've arrived on Vannevar Bush's doorstep, even if we will go no further for now, as I am waiting on the H-bomb announcement, still several months away. 

It's interesting, by the way, that a licensed Japanese version, appears to have been involved in the invention of the tunnel diode. Or maybe the JDAF just put a tunnel diode in their version to support the home side. I don't know, but hope to find out!  Anyway, I've decided to pretend, for as long as it is viable, that Tizard was fighting for the 984. When it comes to ABM, a distant future technological goal to pursue is a much greater social good than anything actually installation-ready. It's like the great cures for the common cold, which don't actually cure common cold, but which are definitely worth the effort. 

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