The big thing that we're told, again and again, about WWI is that the world went into it not anticipating the impact of new military technologies. I want nuance here. I've suggested that the impact of the machine gun is overstated relative to the rapid fire gun. But I'll pivot on that when this discussion gets to its end. As I've already signalled, I'm going to suggest that the light machine gun is a hugely socially transformative technology. I'm just taking my time getting there because the argument that I can feel in my mind looks so much more convincing there than in any form that I've so far articulated it.
So I'm not going to talk about that, but rather something else where the timing of the great industrial-social-strategic rhythms of the Twentieth Century were determined by this (understandable) failure to extrapolate the scale of the tactical transformations that took place in 1914--18: the gas engine.
So we know that WWI came in the early stages of the transition to the auto age. Henry Ford launched the Model T in 1908. Both sides used trucks and armoured cars in the earliest stages of the war, and there were lots of trucks, then tanks. The old potted history that I used to get pushes things back to the first automobiles in the late 1880s, so it was a bit of a revelation to me to find that internal combustion engines were first used commercially as regenerators in open hearth steel plants, extracting additional energy from waste gas. Now, of course, we have Wikipedia and its completists, and you can find a timeline pushing the story of the internal combustion engine back into the 1830s, albeit still leaving out my steel plant applications.
What matters here is that the great powers entered WWI without any sense that this particular technology was one that needed to be pushed to the limit to produce peak horsepower per unit weight. I mean, sure, that's always an engineering goal, but, say, high power/light weight diesels and electric motors didn't turn out to be a potentially war-winning technologies. The gasoline engine was unique, because performance turned out to be so vital to air fighting, and air fighting turned out to be so much more pervasive and important than could have been guessed in 1914, even by the air enthusiasts.
As I say, the issue here is timing. The French army, having pushed aviation technology even before the war, had some nice engines delivering in the range of 100 to 200hp. The Germans had imitated them (unless I'm understating German innovativeness in the interest of brevity) and the Americans and British licensed them. That wasn't a very satisfactory state of affairs, and the Ministry of Munitions went looking for "All-British engines." The story of the Rolls-Royce Eagle, which was requested (Wikipedia says) in August 1915, actually ordered in January 1915, first run on the bench in February, and first flown in December is hair-raising compared with the development periods of even a few years later. The first flew in ordered in Napier Lion, Rolls-Royce Condor, and what became the Armstrong-Sideley Jaguar and Bristol Jupiter were all emerging from the woods as the war ended. This is hardly surprising. Reviewing the trends of the era, F. R. Banks noted in 1950 that hp per cubic inch of piston displacement had risen two-and-a-half times from the sporting engines of 1909 from 0.12 to 0.3 in 1919.(1) Bristol Aeroengines "officially" recalls that the Bristol Jupiter came to it from Cosmo in 1920 along with boy chief designer Roy Fedden as a 9 cylinder engine with a 7.5" stroke and 1500 cu. inch capacity projecting 450hp, although as late as 1922, the Jupiter III the first of the series to pass a 50 hour type test (i.e., it ran on the bench for 50 hours.(3) Putting aside various dreams for various two-row designs, Bristol, or, rather, Fedden, with a staff of only 50, committed to getting the Jupiter into service. (2)
They were finally rewarded by a 1923 Air Ministry contract for a 436hp Jupiter IV. Air Ministry imprimatur guaranteed export sales, and in later years Bristol engines were to be manufactured under license in, among other countries, Sweden, Poland, Czechoslovakia and the Netherlands. (And Germany, too, although the Air Ministry there understandably ended this dependence as quickly as it could after the beginning of air rearmament.)
Almost a decade after the panicked recognition that the air war would require new high performance engines, one of the later mainstays of the industry was finally actually delivering a version of an engine that had been contemplated within the industry since before it was really an industry. The era of the improvised war engines, the Bentley radial, Hispano Upright 6, and Rolls Royce Eagle was finally, decisively, at an end. By 1929, hp per cubic inch had risen to 0.4, both a significant increase and a comment on the overall slow progress of the 1920s, given that the increase to 1939 would be to 0.59, and through 1945 to 1.34.
Taking the latter as the key figure of merit, I guess you could go two ways here. An early twentieth century Ray Kurzweil would be disappointed by the levelling off of exponential growth. No automotive singularity for us! In absolute terms, however, an increase of 0.85hp/cubic inch is much more impressive than one of 0.18. It implied more than doubling horsepower per square inch of piston, an increase in typical engine speeds from 1900rpm to over 2500. It required the development of supercharging and higher octane fuels. Turning all of that power into thrust meant changes at the propeller end: reduction gearing to reduce propeller tip speeds as engine rpms went up and pitch variation by rotation, so that the airscrew turned to present a more aerodynamically favourable angle as engine power output increased.
Looking at the inside of an engine of circa 1942, engineers of the day focus on gearing and metallurgy. In material terms, the miracle is that the same old components are withstanding higher stresses and temperatures. As mechanisms, it is just amazing to see engine power fed to the airscrew through gears that do not fail at these speeds, and via a pitch-changing mechanism that similarly withstands these enormous rotational speeds. More power is taken off by gears or auxiliary drives and used to run mechanical superchargers (even American turbocharged plants have engine-driven superchargers for takeoff boost). We have a pistons moving at thousands of feet per second to drive a camshaft at thousands of rotations per minute to run a gearshaft that ultimately turns the turbine blower that compresses the air charge into the pistons at more thousands of rpm. As if that isn't enough, some of the more inventive firms use hydraulic transmissions on the supercharger, or interpose engine cooling fans, or put a second state on the supercharger to further compress the charge after it has been run through an intercooler.
And it all works! More or less. I confess that I shudder a little bit thinking about men up in the air in single-engined machines running these monstrosities, and the accidental failure rate was quite high. I suspect far too high to maintain operational efficiency in the Japanese and perhaps Russian cases, but, still, not nearly as high as you'd expect when you look under the hood at a Rube Goldberg contraption like the Napier Sabre.
Behind that, though, is the story told by a staff writer for The Engineer in a visit to Derby sometime before March 1942. The writer reports how light machining is now carried out on specialised equipment by female labour at the plant and in dispersal. Cylinder liners are done by a Bullard boring mill. Camshafts are bored out by rifle boring machines. Cams are formed and ground by equipment built at Rolls-Royce. Grinding is similarly done by machines designed and made at Rolls-Royce. Supercharger machining is by equipment "including" Heald Borometers, Cincinnati Hydrotels, and Natco multi-spindle milling machines. Another Cincinnati with hand-tracing attachment does cylinder blocks and crank case section. Cylinder boring is with an Asquith boring mill. Specially designed Borometers and Cincinnati Hydromatics "assist output materially and relieve the labour problem." Ambrose Shardlaw, cincinnati broachers, and Landis grinders do crankshafts. "Orcutt gear grinders among other equipment produce the 80 kinds of gears (some needing 50 operations to produce.") (4)
The aeroengines of 1942 are far more complex, and far more powerful than the ones of 1914, or for that matter 1918 or even 1939. Indeed, throughout the period there is a general pattern of acceleration under state impulsion. This would be an interesting story for military historians if it were confined to the specialised technology of military aviation. But it's not. The story of machine tools "diluting" skilled labour is, of course, an old one, going back to WWI. It was not, however, in WWI, a story about internal combustion engines. In 1942, it is.
Rolls-Royce and its principal machine tool suppliers are collaborating on the mechanisation and automation of automotive engine production on a massive scale. And that is certainly interesting and relevant for any era of automation. On the one h and, it is interesting to see the transfer of skilled labour from the business of building engines to designing machine tools. Again I have occasion to regret that so far the only people to treat the rise of the "programmed" machine tool are David Noble and Kurt Vonnegut, because the overarching story here is just how wrong they are. We do not see automation reducing the amount of labour in the industry. What we see it doing is producing more, better aeroengines.
Now, that's specifically because the war creates unlimited demand for labour. There can be no such thing as unemployment, innovation-driven or otherwise, when the war machine can consume everything that labour can produce. Yet there was also no innovation-driven unemployment in the post-war era, when the technologies developed at Derby spread through the automotive industry as a whole and transformed our driving experience. One story about this is that the supply of newer, better cars created its own demand. Another version of it might be that the Baby Boom created the demand that spread the technology. I like that story better.
1. F. R. Banks, "James Clayton Lecture: The Aviation Engine," Jour. Inst. Mech. Eng. 162 (1950): 433ff.
2. "Bristol Fashion, II: Rise of the Radial," Flight, March 9, 1939: 236ff.
3. 6% of hours at takeoff rating, 27% at rated power, 0.6% at "overspeed," if you were wondering, and if it matched the later Air Ministry standard. Arthur Nutt, "Aero-Motors and Their Development: An American Viewpoint," Flight, December 29, 1939, 841.
4. "The Rolls-Royce 'Merlin' Aero-Engine,' The Engineer, 6 March, 1942: 199--201.