Chapter CLIX: A Season for Decisions Part 1.
Chapter CLIX: A Season for Decisions Part 1.
The realities of aircraft development were such that even if there had their been no changes to the aero engine development plans the RAF Air Staff would still have had many decisions to make in the Autumn of 1937. The development of a new aircraft, particularly a large or ambitious one, was not a quick process and even with the more 'streamlined' approach taken by the Churchill Air Ministry it could still take several years to go from writing the operational requirement to a fully operational squadron. Given the speed of technological advance an aircraft could go from cutting edge to only fit for second line duties in considerably less time than that, consequently it had become standard practice to begin looking at the next generation of aircraft even before the prototypes of the current generation had finished testing, so as to keep a steady stream of 'modern' aircraft entering service. For all that the biggest threat to a design was generally not the advance of technology but the sometimes even faster changes in priorities and strategic thinking both within and without the Air Ministry. The most recent set of defence priorities had been set at the Imperial Defence Conference the previous year, or at least the general ideas had been discussed there and had subsequently been worked over by the Committee of Imperial Defence and turned into some slightly more practical service specific priorities. For the Air Ministry and RAF these were;
• Home defence
• Provision of the aerial component of the expeditionary force
• Support for imperial security and policing missions
• Far Eastern operations
At first reading nothing on that lists seems to require or even suggest that "Build a large fleet of strategic bombers" was an intended priority, yet it was with the bombers that the Air Staff started their work. This was not just the bomber barons taking advantage of the still somewhat vague nature of the priorities, but a reflection that the Air Ministry still saw a significant role for bombers of all types across the priorities. To start with Home Defence while politicians were increasingly seeing that as being a job for fighters and the various Chain Home systems, the deterrent effect of a large bomber fleet was still valued even by those who doubted the 'morale effect' was quite as strong as Bomber Command had claimed. Moving to the next point one of the results of the Chetwode Reforms had been a standing Expeditionary Force, while mostly an Army affair it was intended for the force to have an aerial component for everything from artillery spotting through to air attacks on depots, bridges and similar targets. Much of the detail was still the subject of a three way tussle between the Army, Strike Command and Bomber Command as we shall see in the following chapters, but all agreed that bomber support would be required in some fashion. 'Imperial security' was the latest incarnation of the Air Policing role that the RAF had been carrying out across the Middle East since the early 1920s, most recently in 1934 when they had supported the High Commissioner in Aden and the local pro-British Emir. While not a solution to every problem a squadron of RAF aircraft was a valuable reminder of British power and an efficient way of supporting favoured local rulers and preventing local difficulties becoming problems London had to do something about. This priority was therefore a reminder to the Air Staff not to neglect this mission which was a priority for the Foreign, Colonial and Indian Offices. Finally there was Far Eastern Strategic Operations which perhaps had the widest range of interpretations, politically it had been seen as defence of Singapore through fighters, reconnaissance craft and torpedo bombers to support the fleet and the RAF and Dominion Air Forces had deployed squadrons accordingly. The difference was the Air Staff looked beyond that towards strategic bombing of the Japanese Empire and eventually the Japanese Home Islands themselves, in line with their belief that air power alone could win any war if your just applied enough of it. If the politicians had truly intended this is less than clear, however the CID and Air Ministry could see the value in a credible Far Eastern bomber force if only as a deterrent, so were prepared to let the Air Staff attempt to prove such a thing was possible.
RAF Brize Norton, one of the new training bases built under RAF Expansion Scheme A it was declared operational in the summer of 1937 when No.2 Flying Training School and it's collection of biplane trainers flew in. The distinctive 'ribbed' roofs of the four Type C Hangars are clearly visible as are the other station buildings clustered to the left of them on the picture. What is not visible are any marked runways, instead a faint perimeter road marks the extent of the large grass 'flying field' while the shorter cut grass which marked out the 'runways' are not visible in the photos. A properly levelled and drained grass runway was surprisingly all weather capable, but only if the newly laid grass was given at least three years to properly form its root structure. The various attempts to short cut this process almost uniformly ended poorly, the most notorious example being the 'sinking planes' at Gatwick airport over the winter of 1937/38. Equally relevant for the Air Staff was the fact that a grass runway was far less efficient than a concrete or tarmac one, a bomber that needed 1,500 ft to take off on a grass field would only need 1,000 ft on concrete.
Before looking at the two bomber projects under consideration it is worth understanding the implications and consequences of a key concept that was in both specifications - overloaded launch. As we have seen for much of the 1920s and early 1930s the notional enemy for the RAF was France and ranges were set accordingly, the 1934 specification for the Whitely has been the first where the range had been set with Germany in mind, specifically the target was Berlin. As the plans department and economic warfare department really started studying Germany it was soon noted that while the Ruhr was the economic heart of the country the industry in eastern Germany and Silesia could not be ignored. To hit those targets a 'radius of action' of 700 miles would be needed, adding on the fuel for take off, landing and provision for emergencies and combat this meant a nominal range of 2,000 miles would be required. The issue with achieving such range was weight, more specifically the weight of the loaded bomber at take off and so the required runway length; all else being equal a heavier aircraft will have a higher take off speed and so need a longer runway to reach that speed. With advances in flaps, variable speed propellers and engine power this was considered achievable on a typical grass strip of the time, but anything heavier would require a longer runway than existed at many of the RAF's older Great War era airfields. This was where overload came in, for missions that either required either much longer range or very heavy bomb loads the aircraft would be 'overloaded' with extra fuel and bombs and then launched via a 'frictionless take-off device'. This deliberately vaguely defined device would rapidly accelerate the aircraft to take-off speed in a very short distance and so bypass the runway limitations entirely. In practice the Air Staff expected the device to be a catapult, various iterations of which had been trialled since the 1920s and were in regular use on Royal Navy ships to launch scout planes. Crucially though no firm decision had been made as the Air Staff were concerned with the result not the specific method, while this did leave space for bad ideas such as large flywheels or 'gravity launch' (harness the power produced from dropping large weights down wells) it also meant more useful options could be developed.
Overload had been a pre-Abyssinian War idea and when the Air Staff came to reconsider it in light of the revised post-war defence priorities the situation had changed considerably. With the need to plan for operations in the Far East range had become even more important and as we have seen in-flight refuelling was being investigated as a range-extender, but it was not without it's own drawbacks, not least the large number of tanker aircraft required. The extra range allowed by an overload launch was therefore attractive as it didn't 'waste' any aircraft as tankers. The bad news came from the Royal Aircraft Establishment (RAE) who had been working on the catapult launch option for several years and had produced a preliminary design, the implications of which were unfavourable to say the least. The RAE confirmed that technically a catapult capable of launching a 30tonne aircraft in a very short distance was entirely possible, however it would require a great deal of power (around 8-10,000 HP), a fairly complex rig which would limit cycle time (several minutes per launch, meaning it could take up to an hour to launch a whole bomber squadron) and somewhat ironically a concrete launch track, indeed to allow for wind direction changes several concrete launch tracks. The irony being that part of the motivation for the 'frictionless take-off device' had been to avoid the costs of converting existing grass airfields to concrete or laying new ones. With an estimated cost of around £100,000 per catapult it was still cheaper than building concrete runways, a three runway arrangement with concrete paving was estimated at around £200,000, however the specialists required for the pneumatic systems made it far more challenging to install at overseas bases. The limited cost advantage and the serious operational problems were enough to see the catapult option shelved, though the RAE catapult section would survive by becoming a joint operation with the Admiralty. While the Air Staff hoped this would be a cheap way for the RAF to keep their options open the section soon became entirely focused on ship-borne devices for float planes and hydraulic catapults for aircraft carriers. This was not the end of the overload launch option however, as mentioned the requirement had been non-specific on launch method and in amongst the many bad suggestions there was another far more viable option, RATO - Rocket Assisted Take-Off. RATO had been identified by the RAE as a possibility in a report in early 1936, this was not a particularly insightful conclusion as Germany and the Soviets had been independently testing the use of rockets since the mid 1920s. The principle was exactly as simple as it sounded, rockets were attached to the aircraft and rapidly accelerated it up to take off speed in a very short distance. As the next generation of bombers had been designed for overload it was believed they were already capable of taking the loads imposed by this acceleration, thus the only issue was the rockets themselves. At this point we must once again delve into the world of inter-service rivalry.
The almost incredibly unimpressive cordite filing room at RAF Martlesham Heath, the then home of the Rocket Establishment alongside various other research groups. British rocket research had focused on solid fuelled rockets and had developed a new solvent free form of cordite to power them, unimaginatively called Cordite SC (Solventless Cordite), along with a range of tools and techniques to manufacture the rocket bodies. By late 1937 had produced a fairly powerful 2" diameter rocket and were looking at scaling it up to 3". While far from the most high performance rockets in the world, they were cheap, reliable and optimised for mass production. This was something of a hallmark of all the groups working at Martlesham Heath, a willingness to select a second best approach in the cause of getting something working faster.
The Rocket Establishment had been established to meet Army and Air Force research requirements and so to avoid excessive squabbling fell under the CID, that body had set the original research objectives;
• Anti-aircraft defence
• Long-range attack
• Air-launched weapons
The first was the cheap rocket weapon the Army had hoped would be a more economic alternative to heavy AA guns, long-range attack was the latest iteration of LARYNX which hoped to hit targets several hundred miles distant, while the air-launched weapon project was an idea that had come from the Tizard Committee about the potential for defending fighters to launch barrages of rockets at formations of enemy bombers. Notably absent was any rocket assisted take off idea, not for any technical reason but because at the time of the establishment being started the Air Ministry was focused on catapults and did not see the need. When there has been no functional rockets there had been very little dissent about the order of the priorities as in principle and indeed in practice, the same rocket engine and body could do multiple jobs so the work advanced all the objectives equally. The successful testing of a viable rocket focused minds about which project would get priority for practical implementation and so the RATO work became part of the ongoing inter-service discussions. The starting point was that the Army had a good claim to top priority, just as for the Air Ministry the priorities for the War Office had been set by CID and Home Defence was their top priority for them. As the anti-aircraft rockets were intended to supplement, and perhaps even replace, the existing AA guns assigned to home defence they inherited this priority. If one stuck to the intent of the system then home defence was more important to the cabinet and Westminster than improved bomber performance, thus the Army should win out. Fortunately for the Air Staff the Imperial General Staff were prepared to negotiate the point, not out of any high minded duty but because of the nature of the new rockets. While the prototype 2" rockets had the power and endurance to hit targets at 15,000ft or more the accuracy at that height was terrible, as a result even after making a generous assumption on how cheap a mass produced rocket could be they seemed a less cost effective solution that heavy AA guns. What would make a difference was improving the accuracy of the AA gun predictors, something with the ongoing radar work on the Gun Laying Radar was intended to do. The War Office proposition therefore was that if the Air Ministry's larger and more experienced radar team would provide extra assistance to the Army Cell working on AA radar, then the Army would allow AA rockets to drop down the priority list. The CID soon weighed in to agree that joint radar research was obviously better than many separate siloed teams the Air Ministry agreed the point before something was forced on them. The two ministries agreed that both the air launched rockets and the AA rocket programme would benefit from increased accuracy, so this would be the second priority after RATO for the Rocket Establishment. The long-range attack idea, while enthusiastically endorsed by the Churchill and the Air Council, had become stuck on the issue of control and guidance. It was therefore agreed that the Rocket Establishment could safely ignore work in that area until the control issues had been worked out and there was an actual rock requirement for them to work on.
A Whitely Mk.IV heavy bomber with two RATOG (Rocket Assisted Take Off Gear) pods attached, undergoing trials near Orford Ness. The RATOG pods are the two items outboard of the engines, one on each wing, and consisted of a cluster of rockets bundled together into a steel tube and then fired sequentially to provide extra thrust at take off. As this was a trials aircraft the pods remained attached so the scientists and engineers could study them when the Whitley landed, one of the priorities for the trials flight was to assess what the impact of the pods was on aerodynamic performance and range, to determine if a detachable pod was worth the cost in terms of lost and damaged dropped pods. An early key finding was confirmation that the stresses imposed from a RATO launch were not particularly severe, opening up the possibility of much wider employment of the technique.
A trials unit was soon established at RAF Martlesham Heath, initially with a flight of Armstrong Whitworth Whitley bombers on the basis that they were the nearest in size to the future heavy bombers. Almost inevitably this unit would be joined in the summer of 1938 by one of the first production Vickers Wellington bombers, as the 'Empire Bomber' it would have to operate on everything from Australian dirt strips to frozen fields in the Canadian high north, to say nothing of it's deployments to the Middle and Far East. The RAF (and indeed the RAAF and RCAF) had high hopes that RATO would avoid the need to upgrade and improve quite so many runways to get the maximum range and capacity out of the Wellington. It should be noted that the enthusiastic rush to trial RATO did not mean the issue of concrete vs unpaved runways had been resolved, aside from the range/weight issues it was recognised a concrete runway was more resilient than a grass strip to extremes of weather but that this had to be set against the extra cost. To the distress of the Air Staff the runway debate would soon get dragged into the ongoing airplane vs seaplane battles that were still raging inside, and outside, the Air Ministry, as we shall see in the following chapters. For now it is enough to say that RATO was seen as a way of keeping options open and that overloaded launch remained a valued ability. As we are now hopefully in possession of a better understanding on the priorities of the Air Staff and the Ministry, let us turn our attention to the aircraft themselves.
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Notes:
As is traditional this one somewhat got away from me, but in an interesting way I hope. The priorities are not quite OTL as they do reflect the many change, however aerial policing remains something that much of the government is interested in and doesn't want the RAF to forget about. The RAF operation in 1934 in Aden was an interesting thing as it was (in OTL) the last aerial policing before WW2. The RAF had got the technique refined by then and were operating in support of the High Commissioners negotiations not instead of them, while not phrased that way they were aware of 'minimum use of force' and lots of other counter-insurgency thinking that would get used post-war. I also wonder if it the success also influenced wider RAF thinking as it was mostly the psychological ('morale') impacts of the bombing that did the work, 95% of the bombs dropped were 5lb 'bomblets' that were noisy but basically harmless, with the occasional dropping of larger bombs as a threat.
Catapults and Overload were a key strand of Air Staff thinking, because most of the WW1 era grass runways would struggle to cope with long take offs and the Bomber Boys really wanted to carry big bomb loads to long ranges. In OTL the massive investment in Expansion Air Bases in the East of England provided a large number of much longer runways, though eventually they would have to concrete most of them just to get good all weather performance and to cope with the ever larger weights of the bombers. The 3 years for grass to 'root it' was something that was a well known rule of thumb but often ignored due to pressure to get things operational and was another driver for concrete runways, particularly once you needed bases for the USAAF there just wasn't time. In any event this meant there was no need for catapults as the RAF could just set very long take off lengths, not quite the case in Butterfly though the problems with catapults remain.
The Whitley RATOG tests did happen but that photo is from 1943. There was some earlier work done spring 1941 but that was FAA/Navy driven. That said the 1936 RAE paper is OTL (as is the Germans and Soviets doing it first), however RATO was a very low priority for the rocket research team so very little happened. OTL AA rockets remained the top priority of the rocket team and the date for developing a decent 2" rocket is correct, the change is the deal on changing priorities. In a world where radar is more widely known, if not necessarily more advanced, a gun laying radar solves the Army AA problem far better than cheap inaccurate rockets so this makes sense to me. Also the British armed services may mock each other and disagree over priorities, but they are capable of sometimes co-operating for mutual benefit. Of course when budgets are tight and cuts have to be made, the infighting can reach Imperial Japanese levels.
The long range missile project is surprisingly OTL, as early as 1936 ideas were being sketched out but again at a very low priority. As described guidance and control were the main problems and didn't really get sorted until well in the 1940s, so this stays on the back burner for now while other boffins try to solve the problem. Air launched anti-bomber rockets were also on the 1936 list, but Fighter Command wasn't fussed and there was some doubt about whether the enemy would operate large formations of bombers or use other tactics. Broadly the same here, so again remains a lower priority but still being thought about and poked.
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