John Lilley

The RAF Bomber Command lost 55,000 airmen in WW2, although the USAAF also had losses which amount to not THAT dissimilar levels of horror, they did so in daylight and without really effective escort until quite late in the war. But arguably daylight without top class escort proved to be not much worse than bombing at night unescorted. What always bothered me was, given how heavily armed the American heavy bombers were, WHY did we send so many pilots out armed with what were more or less pop-guns? Luckily, an Operational Requirements War Diary gives much of the story of why Bomber Command had heavy bombers with such light weight defences. When the British heavy bombers we all know were being planned, 303`s in power operated turrets WERE in fact pretty state of the art, and were dramatically better than the German tactic of having hand aimed guns (this is confirmed in WW2 German files also). However, around the time of the Battle of Britain, self sealing fuel tanks, armored glass and aircraft steel armour plating generally gave the Luftwaffe quote: "comparative immunity from small arms fire". The British Air Staff were not surprised by this and had been planning for the day when 0.5" or 20mm cannon turrets would be needed back in 1939. After deliberations they decided that 0.5" was not enough of an improvement, and decided upon 20mm cannon turrets for the first new bomber specification issued to tender in January 1939 (B.1/39), which require EIGHT 20mm cannon. Plans were made that the current operational and soon-to-be operational bombers could be converted to two, 20mm turrets. However, the Air Staff had underestimated the additional equipment needed when war arrived, and the bombers rapidly became so overloaded with armour plating, new radios and suchlike that the designers stated the center of gravity of the bombers would not stand 20mm turrets whilst retaining safe flight characteristics. (a 2x20mm turret weighed 350lbs more than a 4x303 turret and had triple the drag). At this point Lord Beaverbrook cancelled the B.1/39 programme, and also, all work on 20mm turrets (some time before mid 1940). It was then decided that .5" guns were needed, as an improvement was required and 20mm was no longer an option. However, no 0.5" gun was being manufactured in England at the time, and the USA only promised a low volume of "export" pattern 0.5" guns (inferior to American service guns). When tested these showed only marginal gains over the .303. Britain then entered into talks with Breda and FN, in Italy and Belgium respectively, but when Italy entered the war on the German side and Belgium was overrun, this plan floundered. Boulton-Paul designed a 0.5" gun turret for manufacture in the USA, but trials at night showed that it was very hard to damp the 0.5" muzzle flash at night, which rapidly blinded the gunner and studies showed that such heavy turrets seriously lowered the range of the bomber, and it was inferred that the 0.5" gun at night was further rendered of low utility as the main ballastic advantage was longer range than 303, but at night, the gunner could never see far enough away to engage at the range where the 0.5" could "reach" out so much further than the .303 anyway. The Air Staff concluded that therefore any armanent upgrade at night, was useless until the Mk II gyro gunsight was in service (letter dated 23rd Oct 1942) Hopefully this helps explain the story of why the RAF had to endure such poor armament for so long, although it does seem that had it been given maximum priority, its possible that some more serious modifications could have been made the the bombers to apply very heavy armaments. However, the whole reason that the Lancaster could carry so much bombload compared to American bombers, was that it was designed to carry maximum bombload so less bombers were needed, at the cost of armour and weapons when used at night. So to have outfitted them adequately would have required material and doctrinal shifts in parallel, which was probably asking too much. There were though, clearly many very sound and intractable reasons why larger armaments were not adopted, and so it was not just a case of wilful neglect of the Air Crew.