Liveblogging 1939, August, I: Technical Appendix: Stooping to Conquer

According to the 12th Edition of the Encyclopedia Britannica, the edition that actually was what the Eleventh Edition is often claimed to be, in the late 1930s, in the wake of the recent success of the National Grid, the city of Birmingham had begun to offer a new civic utility: high pressure water on tap at 800lb/sq into run hydraulic machinery directly off city mains.

By the Constantinesco principle of wave transmission, the next step would surely have been alternating-pressure transmission. You could run a differential analyzer with that....

Anyway, roads not taken, roads taken and placed under erasure. Here's Not-Rosie-the-Riveter:

Aviation, November 1943

Because I am who I am, I own this photocopy as an answer to excessive reliance on the notorious Fedden Report, the intended punchline being rather that these engineers are graduates of a nine week night school class. If you're not consumed with the desire to punch the awful Correlli Barnett in the face, you might look at this and conclude that there is a social issue at stake. Anyway, it eluded me at the time. Here is Martha Robertson, of Vega Aircraft.

 I'm not the gender history guy, but I will try to take a road through my own country that gets back to this point at the end.



Start with this:

A flight of Curtiss F-8C Helldivers. I've lifted it from some kind of English-language alt-history Finland site becase MGM apparently can't be bothered to get any good airplane stills out of 1932's Hell Divers, the first starring role of Clark and the dive bomber. Although, in spite of the title, the Helldiver was not designed as a dive bomber. The basic premise of the biplane being a structure that was light and lifty enough to get into the air behind a lawnmower engine, practically any biplane, like a paper airplane, could be all but stood on its nose and pointed at the ground, and would zoom out of its dive in good time. 

Not a bad way to pick up chicks, MGM thought, as it took a small cheque from the navy to make something fast and cheap to get Gable's face on the marquee. The navy lads stooging about Los Angeles probably thought it had advantages for bomb aiming, that it might even be a way of sinking ships, granted a design that could actually fly from a carrier deck, a mission that challenged the Helldiver, like many early would-be carrier planes.  

So a guy named Ernst Udet went to see the National Air Races, was taken by "dive bombing," and went back to Germany to sell it as a force multiplier. We know what happened next:

Simple, robust, lots of lift and lots of drag. Unlike many other single-engined bombers (1, 2), the Ju-87 took the back seat and filled it with a gunner rather than a bombardier. It worked okay. The popular history of the Ju-87's operational history is that its particular characteristics made it vulnerable to enemy fighters when the Germans lacked air superiority. The popular history of World War II aviation needs to reacquaint itself with the second raid on Schweinfurt. That being said, I've no doubt that dive bombing was a dangerous thing to do. I will even concede that enemy fighters made it more dangerous.

Here's the thing: if you are the Fifth Sea Lord, and it is your dream to sink the Italian navy with dive bombers, then I have a project for you.

But say that you want something more ambitious? Something like the "torpedo fighter" that Blackburn sold the Navy in the 1920s. (Although the Dart was only a fighter in the sense that it was a single seater, and it was a single seater because the designer couldn't find disposable weight for a back seater, the Dart was eventually claimed retrospectively as a precursor to an actual torpedo fighter. Still a solution looking for a problem, but at least something that could be defended as a fighter. [1,2, 3])

But before you get there, you're apparently going to have to play this whole dive bomber thing through:

Blackburn is, I think, the only member of the British aviation industry circle to get through WWII without a type in continuous service. And it is because of this ship: the Blackburn Skua fighter/dive-bomber. This line drawing appears in summer numbers of both Flight and Aeroplane, so it probably originates at Blackburn and was released through the Air Ministry. With WWII on the  horizon, the Skua was as far off the Secret List as it could possibly be.

In other words, its career was over before it started, though, to be fair, Skuas would shoot down a few planes and even sink a German light cruiser. Though, again, we are talking about a technological novelty needing to be put out its misery. (A central diesel engine was supposed to give worldwide wartime cruising range. It didn't.)

It's not hard to see why Reggie Henderson's incoming replacement gave up on the Skua. Blackburn had been more than amply rewarded with a series of huge production contracts: 192 Skuas, 136 Rocs. Not big by the standards of what was to come, but bear in mind that in the spring of 1940, the United States Navy had a total of 181 fighters and 740 bombers. That's units on hand, not squadron service.

The result was distinctly disappointing. In service fighter configuration, the 5,490lb (empty weight) Skua gave 225mph at 6500ft. The curse of service equipment is implied by the official performance of the target tower variant: 229mph at an unspecified height. This is not quite as bad as you might think at first glance: the 300mph+ fighters of the Battle of Britain were significantly slower at 6500ft. But it is bad, and you do not have to spend much time crunching the numbers to see why: 6.06lb/hp empty weight, compared with 3.89 for the Zero, 4.41 for the Bloch MB-150, 4.91 for the Grumman Wildcat, and 3.87 for the Gloster Gladiator.

Taken by itself, though, the project was not unsalvagable:

Here's a Wikilift: the stats block for the Bristol Perseus:

Type: Nine-cylinder single-row supercharged air-cooled radial engine

Bore: 5.75 in (146 mm)

Stroke: 6.5 in (165 mm)

Displacement: 1,520 in³ (24.9 L)

Length: 49 in (1,245 mm)

Diameter: 55.3 in (1,405 mm)

Dry weight: 1,025 lb (465 kg

And for the Bristol Taurus:

Type: 14-cylinder, two-row, supercharged, air-cooled radial engine with dual ignition

Bore: 5 in (127 mm)

Stroke: 5.625 in (143 mm)

Displacement: 1,550 in³ (25.4 L)

Length: 49.2 in (1,250 mm)

Diameter: 46.25 in (1,175 mm)

Dry weight: 1,301 lb (590 kg)

1100hp at 275 more pounds would give the Skua a much more respectable 5.21 lb/hp, the drawback being that the plane would have had to be completely redesigned to make use of the almost 9" reduction in engine diameter. In the event, hardly anyone used the Taurus. Or the Hercules, or the Centaurus. It is not, in the end, at all amazing that Roy Fedden was sacked as head of Bristol's aeroengine division and packed off to see America. It is a bit amazing that he was treated as an oracular seer of the future of technology when he returned to Britain. But somewhere on the Internet I have heard it theorised that always being wrong is no barrier to success if you are wrongly convinced of things that policy makers would like to be true.

Beyond problems with the engine, though, there is a more telling reason why the Skua programme was abandoned. Gesturing to dubious memory, I am going to cite an article on the development of the Vultee A-35 Vengeance, seen, per Wikipedia, being built here:

Hi, Rosie! Rosie doesn't have a name, by the way. Certainly not a name like "21-year old Martha Robertson, fresh from college." And I can tell you in perfect confidence that that picture would never have appeared in a wartime number of Aviation, which in a run of four years featured a single picture of a Black man, and felt compelled to label that photo an "Official War Department photograph," a credit that could have run under virtually all of their photos, but, of course, doesn't. Because editorial wants it to be clear that it didn't do anything so gauche as acknowlege the existence of coloured Americans in print.

Women, visible minorities, dive bombers. The article (that I'm waving at) brings them together, at least in my mind, by the Vultee engineer who explains how the Vengeance came to be known for "a number of fatal accidents"

And not, as Wikipedia explains, because of  

 improper dive procedures and a center of gravity problem when the aircraft was flown with the rear cockpit canopy open, but without a rear gunner. . .

That is, those were the causes, but the reason behind that is very simple. If you dive a monoplane, which is designed clean in order to be fast, at a very steep angle, it takes very great control forces on the flaps to pull it out of a dive. And the leverage on the flap that the pilot can apply will depend on the exact point at which the flap is bolted to the next thing along that transmits the control force. 

To give the flavour of it all. I quote Blackburn on the Skua:

The control surfaces are operated by a normal system of cables, pulleys and levers. The control-column has a knuckle-joint so that lateral movement of the upper portion controls the ailerons.

From the upper portion of the control-columns two chains are taken down the column over the sprockets to tie-rods connected to the horizontal arms of a three-armed lever mounted on the forward wall of the bomb compartment, Cables from the vertical arm of the lever are conducted by pulleys down to the centre line of each main-plane hinge-joint into the main-planes to levers linked to the leading edge of the ailerons. A balance-cable connects both ailerons.

One does not have to be able to visualise this Heath-Robinson contraption to see that it is an amazing, and slightly dubious bit of old-time rigging, and suspect that some of the dive bombers of 1940 that did not come home failed to come  home because of what Wikipedia tactlessly calls "improper dive procedures." In other words, it was beyond the strength of the pilot to pull out of a situation that the stresses of combat had put him in, because somewhere along the line, someone had put in some slack, or fastened one piece to another one link too far along, or an inch from where it was supposed to go. 

Moving right along, we get to the Dornier Do-217, a plane that fell into Allied hands at some point in 1942, and which features in a starring role in the Air Ministry "Report on Enemy Aircraft Number 8," which you will find in the December 1942 number of Aircraft Engineering, if you have a really awesome engineering library at your disposal. Otherwise, here's the blurb in Popular Science. While no-one would call the Do-217 a good aeroplane, Dornier set out to build a twin-engine bomber that could actually dive bomb safely, and the technical details of the interlinked tail brake and flaps and propeller and radiator flaps are beyond amazing. Unlike the Skua's hydraulically actuated-dive flaps, the Dornier design used electrics, reflecting the shortage of good-quality mineral oil in the German Reich. Good practice for the future, but I notice, buried deep in the Wikipedia article, that in an evaluation flight, it took 40 seconds for the Do217's undercarriage to retract on takeoff.

On the one hand, electrics tended to be sluggish, although I am not inclined to parse the wall of text that is the current version of the Wiki article, or slog out to the university library to confirm that the Do217's undercarriage even was electric. On the other, I'm going to let Edward M. Greer, President and Chief Engineer of Greer Hydraulics, and Lieutenant Commander Harry J. Marx, USNR (in charge of hydraulics at the Bureau of Aeronautics of the USN) take it away:*

"Even today, we see that, when the landing gear is retracted on airliners made available before the war, one wheel goes up first and the other follows at various rates of speed. This, of course, puts a side load on the airplane during takeoff --a load which must be compensated by the flight controls. 

One wheel rises before the other beause of unequal loads present in the hydraulic actuating unit due (1) to greater friction in one landing gear component over the other, (2) unequal wind loads during takeoff, or (3) friction in the hydraulic actuating cylinders themselves. To obbiate this in the case of wing flaps, it was the practice to emply a single hydraulic actuating cylinder to operate two flaps by mechanical linkage. This is acceptable for commercial a/c, where speeds during landing and takeoff are in the order of 100mph, but not with military a/c, especially dive bombers. where dive flaps must be operated against much greater air pressure. . . .

For this we need [lots of complicated hydraulic stuff] i.e. relief valves, pressure regulator valves, variable displacement or self-regulating pumps, hydraulic power valves and hydraulic boosters and deboosters."

At this point I am going to come around to remind you, as I always do, that by 1943, Dowty Hydraulics ads in the United States advertised that Dowty Live-Line hydraulics "think for themselves." In a more technical sense, Dowty faced the problem of uneven undercarriage retraction in the late 1930s, developed a fedback system that regulated the speed of retraction in one gear by the speed in the other, and extended the concept to its carburetor. By 1943, this idea of "hydraulic circuits" had reached the point that Greer and Marx describe, and which we can recognise in retrospect as an implementation of logic circuits in a parallel development to the one going on on the electric side of the shop, which was to prove to have some future.

The hydraulic logic circuit came and went in the aviation industry. Relatively novel in 1939, when Dowty's high technology swashplate engine developed pressures in the order of 1000hp.sq in, it was a field full of bright promise in  1943, when 5000lb/sq in was in sight, and hydraulicists could not see any reason to use electrics for anything, ever, only to come to grief, mainly on the problem of oil filtration. Dornier was right, after all. 

What interests me here in particular is the intersection between the physical building of a plane, its transformation from a blueprint to finished product, in the context of these new technologies. 

To put it another way, anonymous Rosie is shown to us in the posture of the manual labourer. There does not seem to be a great deal of top-down control over where she puts her rivets, but there does not seem to be a need, either. At the other extreme, the dive bomber tells a different story. Actually, it matters a great deal, and that is why 21-year old Martha Robertson, fresh from college, is measuring what looks like an already-assembled undercarriage, while Lucia Van Buskirk, former interior designer, takes notes. These measurements will differ form plane to plane, and those differences will matter to the performance of that particular plane, in particular to the hydraulics. Human skill has been inserted into the process, between design and serviceable aircraft. It has carved out a place within the technological process, and it is no surprise that, in the American condition, it is taken by 21-year old Martha Robertson, fresh from college. I do not know who Martha Robertson was, although Rootwebs yields a Mitch Robertson, who worked all his life at Lockheed-Vega, and has Marthas in his family tree: plausibly a nephew or brother. I am going to push my speculations a little bit further, and suggest that the odds are good that Martha Robertson's estate was large, and that, if she had grandchildren (or is it great-grandchildren by now?) they went to college, too.

I'm not going to end this by trying to launch into undermotivated grand social theory this time. It is perfectly obvious what happened here:

o) It's a recession, and it sucks. Until someone starts a war, using wicked cool dive bombers.

i) Policy makers want dive bombers. Now! So they threw money at factories to make them.

ii) Making dive bombers turned out to be hard, so the factories threw money at subcontractors to fix these problems.

iii) Subcontractors turned out hydraulics, while the factories turned out the designs to which the hydraulic lines had to be attached. Technology!

iv) This was painstaking work, calling for exact measurements and stuff like that.

v) There was a labour shortage at the time.

vi) Therefore, instead of taking their pick of university-trained engineers, employers had to put anyone they could find through 9 week night school courses and hope for the best.

viii) Somehow, the face of that training programme that Vega Aircraft chose to display to the world was 21-year old Martha Robertson, fresh from college.

ix)????

x) Profit! For the Robertson family, anyway.

All the talk of technology matters here mainly because right now we're talking endlessly about how technology is eliminating jobs. I am going to humbly suggest that we have been down this road before, and that the crucial step from (o) to (x) is not (iii) but (v). 

*"Pressure Control In Aircraft Hydraulic Systems," Aviation, January 1944, 169--72, 360. NB: that is not continuous volume pagination. An individual number of Aviation in the winter of 1944 ran almost 400 pages.

**I might have been suffering from caffeine withdrawal when I abstracted this quote.