Chapter CLVIII: A Sacrifice for the Son of Jupiter.
Chapter CLVIII: A Sacrifice for the Son of Jupiter.
The immediate priority in the Air Ministry's review of it's engine portfolio was the Speed Spitfire project, the aircraft in question would be powered by a heavily boosted and exotically fuelled Merlin II engine. The challenge was formidable as the world landplane record was held by a heavily modified Messerschmitt Bf 109 powered by a 33L Daimler Benz 601R engine, as the Merlin was only 27L displacement the British engineers were starting at a considerable disadvantage. The combined Rolls Royce/Royal Aeronautics Establishment (RAE) team would manage to brief coax over 2,100hp out of the record attempt engine, double what the standard Merlin II of the time could manage, and just in excess of what was believed to be required to take the record. The team did note that that their work to get to 2,000hp+ would have been a lot easier had they been starting with a larger engine and this chimed with a broad trend the Air Ministry technical section had observed, the growing tendency to use clever engineering instead of raw size to achieve an increase in engine power. On it's own terms this approach had worked, comparing the engines in the 'standard' fighter version of the Spitfire and Bf 109 the power outputs were broadly similar despite the disparity in displacement. Within the industry this had been viewed with a degree of pride, clever engineering producing equal results to brute size, while the civil service viewed the whole thing as a matter for the engine manufacturers; the Air Ministry approach had been to specify the power output required and any special requirements, but leave how that was achieved up to the engine designers. The increased importance attached to speed meant there was a growing view that while using clever engineering to match the output of a larger engine was a fine achievement, starting with a larger engine and then applying that same ingenuity would produce engines that out-performed rather than merely matched their foreign rivals. This did not mean the Air Ministry would start interfering with details such as displacement or engine size, they would instead revise their expectations of what was possible and start requiring larger power outputs from future engines. This new perspective would very much inform how the Ministry approached the rest of the engine review and the decisions they made.
The Speed Spitfire in flight over the RAE airfield at Farnborough, the bold 'lightning strike' design visible though sadly the vivid blue colour is not. The world air speed record had to be set at low level, indeed the course had to be no higher than 75m above sea level, and at that altitude a standard Spitfire Mk.I could manage a shade under 300mph in ideal conditions. The Speed Spitfire had double the engine power of the Mk.I, a host of aerodynamic tweaks and a low level optimised 4 bladed propeller, yet the design team were only aiming at just over 400mph. This was a reflection of the harsh realities of drag and speed, all else being equal to double an aircraft's speed did not require double the horsepower, it required eight times the power. These diminishing returns on increased power were another reason the Air Ministry was keen to look at ever more powerful engines.
The review began with Rolls Royce who had no less than seven aero engines under some degree of development or production, along with various other engine related endeavours. This was not quite as bad as it seemed as the engines could be grouped into two main design families and there was a large degree of commonality between the members of each group. The 'bird of prey' family were all liquid cooled inlines and could all trace their lineage back to Kestrel, the mainstay of the RAF in the late 20s and early 30s and still in production for training aircraft. The other members were Peregrine, which was a modernised Kestrel, Vulture, which was graphically described as 'two Peregrines performing an unnatural act in close formation' (it was two V-12 Peregrines bolted onto a common crankshaft to form an X-24 engine), the well known Merlin, and finally the enlarged version of Merlin tentatively named Griffon. The other family was the air-cooled X-shape inlines, both named after rivers and both being developed for the Fleet Air Arm, the Exe and it's still entirely on-paper enlarged version the Tamar. While there had already been efforts to reduce the burden on Rolls Royce by banning them from the marine engine market the considered view of the Technical Department was that this was still a very heavy work load, particularly given the deadlines from the wider aircraft development programme. The Merlin was the engine for Fighter Command's two main fighters as well as several upcoming prototypes for other specifications, in addition the Committee for Imperial Defence (CID) were very quick to make clear that the Dominion Merlin work was a non-negotiable priority on political and diplomatic grounds. With the Air Ministry having just decided that larger and more powerful engines were a good idea Griffon was also safe, while Vulture was one of the specified engines for next generation of fighters and bombers so was also deemed very important. This left Peregrine which, at a mere 900hp at that point, was the least powerful and so a prime candidate for cutting as there were plenty of other engines in that power band, however as a Vulture was two Peregrines combined together much of the development work on Vulture would benefit Peregrine as a side-effect and vice-versa, so the actual savings in time and effort from a cancellation would be minimal. Moreover Peregrine was the preferred engine for the Westland entry to the F.37/35 cannon fighter spec, the P.9 used two Peregrines so the actual installed power would be more than competitive. As Fighter Command were very keen to see a high performance cannon armed fighter in service, and as the Westland design was seen as the lower risk of the two proposals selected for prototyping, this was another good reason to keep the Peregrine under development.
With a grim sense of inevitability the Fleet Air Arm representatives recognised this meant it was one of their engines which was being eyed up for the chopping block. The Griffon was technically an FAA design, or at least they had asked for it before the RAF had thought of it, but the Exe and Tamar were arguably the first modern British aero-engines that had been designed just for naval use. Naturally the FAA did not want to give them up and the Admiralty was prepared to put it's full weight behind ensuring that it got it's way. Their starting point was suggesting that the Air Ministry had been looking at things the wrong way, rather than shrinking the workload to fit Rolls Royce's capacity, surely they should be encouraging an increase in that capacity. Given the tendency of all the armed services to try and throw most engine problems at the firm this would beneficial to all involved and hopefully reduce the need for such brutal decisions in the future. While a reasonable seeming suggestion it was sadly not that simple, not least because Rolls Royce were already trying to expand but so were a host of other engineering firms to meet the rise in military and civilian orders, all of them drawing from the same pool of specialist workers. The general staff shortage was particularly acute for design work, while a new welder or production line worker could be trained up in a few weeks or months an engineering draughtsman needed a five year apprenticeship and a fully qualified design engineer took even longer to educate and train. As any expansion to the training pipeline would not bear fruit until the early 1940s it was a particularly short term solution and indeed the long time lag raised another serious issue; was a far larger industry design capacity sustainable? The current spending was 'Re-armament' which amongst other things implied it was a limited exercise, once the armed forces were in an undefined 're-armed' state then things would return to an equally unclear 'normal' spending level, all of this assuming a future government did not just cancel the scheme. The Air Ministry, and indeed the Admiralty, had spent the 1920s and early 30s carefully protecting design capacity in the face of government spending cuts and so were understandably sceptical about diverting funds from current needs to invest in future capability if it could all end up being cut at the next election. While the issue was 'kicked up stairs' to the CID in the vain hope it might prompt some political action in the short term it was accepted design capacity was a constraint and plans would have to be made accordingly. The main counter-argument from the Air Ministry was that the Exe was not really required, it had a similar power output to the Merlin and so the FAA could just use Merlin instead of an Exe in their upcoming specification. As the FAA believed the inherent damage resistance of an air-cooled engine was important for carrier aircraft, to say nothing of the advantages in not having to include large radiator intakes, this was rejected, the option of delaying Tamar was equally unacceptable as they too could see larger higher power engines would be needed in the future. With neither side willing to compromise, and Rolls Royce management unwilling to upset it's key customers by just refusing work, it appeared the decision was to tolerate over-loading the Rolls Royce design teams with target dates and deadlines pushed back accordingly.
A Rolls Royce Exe on the test stand at Hucknall Aerodrome, home of the Rolls Royce Flight Test Establishment. The starkest example of the trend for clever design and not increasing size could be found in the progression from the Kestrel to the Exe, both had a 22L displacement but power had over doubled from 450hp in the first Kestrel to a shade under 1,000hp in the prototype Exe. There were three main ways to increase power without increasing displacement, higher rpm, higher boost and sleeve valves, and the Exe successfully combined all three. To add to the almost showing off feel of the design Arthur Rowledge had also implemented a novel low-drag air cooling method and done so without any significant issues or any of the panic of the cooling crisis which had hit other firms. The main criticism of the Exe initially was it's power, there were no shortage of 1,000 hp engines and aircraft would soon be needing far more power to remain competitive, but this was not a problem with the design per se but a reflection of the limited ambition of the FAA who had specified it. They had asked for a 1,000hp engine in the smallest package practical and that was what they got, they were fortunate that thanks to hard work and the designers skill the Exe would eventually be developed into a 1,500hp unit, one which could provide the level of power the FAA required.
The deadlock was broken through the slightly unexpected intervention of the Ministry of Defence Co-ordination (MoDC), unexpected because it was mostly received well by the services, at least initially. The MoDC probably had the broadest view of the various projects underway of any group in Whitehall or Westminster, while the CID had a better knowledge of highly classified projects or anything with Dominion interfaces they tended to avoid the details and while the Treasury theoretically knew all, they also tended not to ask about details beyond the price or impact on the economy. As a result it was the MoDC that noticed the potential in Kestrel to both solve a number of disparate problems and to lighten the load on Rolls Royce. As discussed previously Kestrel had been the preferred engine for much of the 1920s and as a result the RAF had a very large number in stock, taken from all the biplanes hastily being pulled from service. Recognising most of those engines were still fairly new the Air Staff has planned not to procure new Kestrel engines for the next generation of training aircraft, but instead to refit the old engines to a new standard. The MoDC had also seen the request for high powered marine engines, while not challenging the decision on ruling out Merlin they did suggest that a marinised Kestrel engine would fit the power and size requirements of both the RAF High Speed Launches and the Admiralty's motor torpedo boats. They also pointed out that the marinisation could be done by a different firm, provided there were a steady supply of base engines to work on. On the land side it was known that after the A9 Tank trials where the Phantom II car engine had failed Rolls Royce had been looking at tank engine supply, while the Army was expecting the next generation of tanks needing a large jump in engine power. An un-supercharged Kestrel engine, even on the much lower octane Army Pool Petrol, would produce around 500hp and so be well within the range the Army was looking at. As final flourish the MoDC suggested to the CID that Kestrel could be the ideal engine for the next generation of aircraft to be offered to Spain, even in de-tuned training-spec it was still a 720hp engine which was a vast improvement over the less than 500hp Wolseley Libra in the Spanish Venom, while being a last generation engine it minimised the risk of modern technology leaking out. Apart from the RAF trainer engines all of these were fairly small projects requiring from a few dozen to just over a hundred engines, nowhere near the quantity to justify a major scheme. As a job lot they were almost the definition of unsuitable for standard mass production as they had very different details and fittings despite the common engine block, crankshaft and other key parts, so the line would be constantly changing to switch between versions. However they were a good fit for a Woollard style approach, particularly if it could be done in a purpose built shadow factory, which was something that could be justified by the total number of all the required variants. Therefore if all the Kestrel work were passed over to a different firm, including the marinisation and land variant development, then Rolls Royce could shut down their Kestrel team and stop investigating tank engine options, freeing up resources for their aero-engine projects and reducing the over-load on their design teams.
While all of this was attractive the killer argument was that such a new factory could pull in funding from a range of non-defence budget sources, especially if it were built in a Special Area, to the point it would be virtually 'free' for the services. A new facility in a Special Area would also gain them plenty of political brownie points for pushing investment towards politically convenient areas and lower the pressure on the other suppliers to relocate their factories. A decent sized production run and minimal capital costs to cover also meant the various Kestrels would be cheap, even after allowing for a reasonable licence fee to Rolls Royce for the design and tooling. The MoDC also had an answer for the short term engine needs, proposing the use of the stocks of decommissioned Kestrels from the RAF and FAA be used for limited rate low volume production while the shadow factory was brought into full production. As was becoming traditional the MoDC attempted to push it's luck and take control of the endeavour, arguing that a scheme that crossed all three services and had foreign export considerations was the very definition of one that needed defence co-ordination. Equally traditionally the Admiralty, War Office and Air Ministry united to resist this bureaucratic empire building, correctly believing the MoDC had the long term aim to wedge itself into defence procurement and so refusing to set a precedent, indeed the service chiefs themselves had a common aim to see MoDC abolished with it's co-ordination duties passed to the Committee for Imperial Defence, which at least had service representatives on it rather than just politicians and civil servants. With that particular round of bureaucratic infighting complete it was easily agreed to proceed with the plan and that the new factory fit within the Air Ministry's existing Shadow Factory Scheme. The chosen technical partner was Henry Meadows Ltd, a moderately sized manufacturer of engines and gearboxes that crucially also had experience of producing marine engines. After a somewhat dispiriting review of the options within the Special Areas, and a number of very serious meetings about whether the extra cost (both financial and political) of going to a traditional site was actually a price worth paying, the location selected was Newcastle. The factory would in some ways be a shadow facility to the existing Vickers works at Elswick, as this would aid in developing the tank engine variant and allow a bit of cross-pollination between the experience Vickers works and the new factory being laid out on Woollardist lines. True to the MoDC's predictions the endeavour did attract a great deal of interest from the various development and investment bodies; the Special Area Commissioners approved the full range of allowances and exemptions, the Treasury approved the necessary grants and the still relatively new British Investment Finance and Industrial Development Corporation was keen to prove it's strategic worth by under-writing it's first defence scheme. Ground would be broken that autumn and by the spring of 1938 the first batches of new build Kestrels would be leaving the factory surrounded by a clamour of politicians keen to take the credit and show off a high profile investment in the North East. Somewhat less well publicised was the low rate production of engines underway in Henry Meadows Wolverhampton factory, these engines would make their way to the various Motor Torpedo Boats, High Speed Launches and Tank prototypes under development in the rest of the country.
The last Ford Model A Van rolling off the production line at Trafford Park, Greater Manchester, in 1931. Such was Ford's reputation and lingering association with the idea of mass production that there were regular calls for the firm to be involved in the Shadow Scheme and the Trafford Park site, which had lain abandoned since 1931, was often touted as a facility that should be modernised and brought back into use. While the site had been tentatively identified as a potential Rolls Royce shadow factory no real progress had been made, in part because Rolls Royce already had two other engine factories under development (Crewe and Glasgow) and given the revised fighter-focused production plans that was predicted to be sufficient. The other part was Ford itself, with Ford US having decided to back the Republicans in the Spanish Civil War relations between Ford senior management and the British government were somewhat awkward. More seriously after the Fordson tractor debacle and Ford UK's ongoing struggles with profitability there were real concerns about long term viability of any scheme. The decision to pursue the more flexible Woollardist approach was the final nail, asking Ford to abandon the manufacturing approach they had pioneered and indeed named would hardly be well received.
There is one other matter to cover before moving on from Rolls Royce, the Phoenix sprint engine. Engine design is normally a matter of balancing various factors; power, size, complexity, efficiency and so on. The sprint engine is the answer to the question "What if you don't care about fuel efficiency?" The concept had come from the Tizard Committee's considerations of aerial defence, at the time it was thought that a defending fighter didn't really need much range but desperately needed maximum power to allow it to climb to altitude, therefore the committee proposed producing a 'sprint' engine that was optimised for short range interceptors. The key feature of such an engine would be the choice of the powerful but wasteful 2-stroke cycle rather than the far more efficient 4-stroke cycle of almost every other aero-engine. Development work began under Harry Ricardo and the concept soon grew in complexity and ambition; sleeve valves, liquid cooling, stratified charge, direct fuel injection, vortex supercharging and exhaust turbine energy recovery were all included in the 'ideal' engine layout. The final concept for the engine was not just one of the most advanced 2-stroke aero engine ever attempted, it was arguably one of the most advanced aero engines of any type. In terms of the Air Ministry portfolio the design slotted in as both speculative and as a backup, not to any other piston engine but to the possible failure of RDF development. RDF had pushed back the warning times and made fighter defence practical, however if advances in bomber speed and height outpaced improvements in the range of RDF then it was feared the situation would change once again and warning times start to decrease. In that scenario have a high powered sprint engine uncompromisingly designed for a raid climbing and interception could be invaluable in keeping fighter defence viable. The original plan had been to hand this immense technical challenge to Rolls Royce for development, however this hit the objections of the CID and indeed parts of the Air Staff about overload and other priorities. After a great deal of wrangling the engine ended up with Alvis-Napier, at least for the single cylinder testing and development phase. The combined company had the facilities from Alvis' brand new factory and technically capable staff from Napier, with Ricardo and his company providing additional specialist support, the question therefore was whether the company had the organisation and ability to utilise those resources, as such the project was also something of a test of the new company. As was standard it was the design firm who named the engine and the choice of the name Phoenix was officially because Alvis-Napier had chosen 'mythical creatures' as the theme for this family of engines, however it is hard not to miss the symbolism of the choice.
Finally we turn to Bristol, who had reason to be somewhat confident about the review. The massive investment in sleeve valves was finally paying off, while the cooling crisis and the problems of their rival radial makers had only highlighted their technical prowess in mostly avoiding such issues. In terms of range they had six engines in production or development, the two poppet valve radials Mercury and Pegasus, and the four sleeve valve radials Perseus, Taurus, Hercules and Centaurus. There had already been a degree of trimming of the range, the Air Ministry culling the far too small Aquila sleeve valve to allow Bristol to concentrate production efforts on the larger engines. Development wise Bristol had hoped to stop work on the 'legacy' poppet valve Mercury and Pegasus, however much of the current generation of RAF aircraft had been designed around them, not least the Bristol Blenheim (which had an entire network of Shadow Factories dedicated to it) and the Vickers Wellington (which was at that time a linchpin of British and Dominion medium bomber plans). As we have seen both engines were getting an upgrade to make full use of 100 Octane fuel, their future development beyond that would be tied to decisions about the high priority, and high profile, aircraft which used them. Turning to the sleeve valves the Perseus had ended up a mainstay of the Fleet Air Arm, powering the Blackburn Skua and the prototype Gloster Griffon, with the Admiralty even considering replacing the engines in the Fairey Swordfish with Perseus to get everything on a common engine and simplify logistics. The Perseus had also been included in a number of RAF specifications for land planes and this gave it a large enough user base that it would also need upgrading to 100 octane fuel. The Air Ministry was concerned at this surprisingly large workload, particularly when they moved to look at the larger engines. The enormous 18 cylinder Centaurus was at least still a mostly paper design as Bristol were focusing on the nominally 1,000hp Taurus and it's larger brother the 1,300hp Hercules. Both were 14 cylinder twin row engines and in theory the main difference was the larger cylinder size on the Hercules, giving it a larger displacement and so more power than it's smaller sibling. In practice there were considerable differences in detail and layout, crucially Hercules was based on the standard cylinder size Bristol had been using since the 1920s while Taurus had a new bespoke cylinder size. This seemingly small difference, and some unfortunate clamp design choices, had made Taurus' development prolonged and unproductive, yet it remained Bristol's priority as the board believed in developing the lower powered engine first. This misunderstanding of the Air Ministry's views was quickly corrected, the Hercules was either first or backup choice in most of the submissions for the next generation of medium and heavy bomber, in contrast the Taurus had not yet even been listed as an approved option for specification. If that were not enough the Air Ministry technical section considered the Taurus as too little, too late; there were already several 1,000hp engines available (Merlin, Dagger, Exe and Sabretooth) at various stages of maturity, so there seemed little point in developing yet another similar sized engine, particularly one which was not even reliably passing type testing.
An Armstrong Siddeley Tiger Mk.VIII being fitted to a Whitley heavy bomber. Bomber Command had originally intended to fit the more powerful Merlin engines to the later marks of Whitley, however they had been over-ruled by the Air Council who prioritised the equipment of Fighter Command. Knowing Bomber Command still wanted more powerful engines on the Whitley the new management at Armstrong Siddeley proposed a further development of the Tiger, dubbed the Sabretooth Tiger (as they were truly running out of big cat names), with a central bearing and various other minor improvements. The first Sabretooth would come out at 1,100hp, almost entirely due to the increase in rpm that the central bearing allowed, which was a significant improvement on the Tiger Mk.VIII but nothing particularly special. The advantage to the relatively simple nature of the changes was that it would take only a few months to go from suggestion to the engine starting type testing and then into the next production batch of Whitley bombers. The Air Ministry took this as further reassurance both that they were adequately stocked with 1,000hp odd engines and that the changes to Armstrong Siddeley were starting to have a positive effect.
The existence of firms beyond Bristol capable of producing an air cooled high power engine was important, not just for the traditional reasons of competition and design variety, but due to some very specific concerns about Bristol at that time. As we have discussed the choice of sleeve valve had been a bold and expensive risk, but which had technically very much paid off. Bristol sleeve valve engines were in front line service with the Fleet Air Arm and on paying service with Imperial Airways, living up to the promise of higher efficiency, better reliability, lower maintenance and lower noise. There was just one small problem; every engine had to be carefully hand finished as they required individually matched cylinders, sleeves and pistons all fettled to fit. The heat treating processes tended to very slightly deform the elements, particularly the sleeves, and the exact deformation was slightly variable. These were small deformations, ovalisation of a few thousands of an inch (0.1 to 0.2 mm) on a 5.75 inch nominal bore cylinder, but this was still enough to ruin an engine unless all the components had the same deformation. For the small volume of engines required so far this had not been a serious issue, as we have seen up to a certain output the fixed costs of mass production outweigh any savings and so small batch craftsman production can be the best option for a run measured in dozens not thousands. Bristol had also been diligently working on adapting the sleeve valve manufacturing process to be suitable for mass production, the problem was they had been working on the issue for several years and up to that point had only demonstrated many dozens of methods that weren't suitable. Given the national importance of the sleeve valve in Air Ministry plans, and the likely requirement to ramp up production of Hercules into the hundreds and possibly thousands, the group working on the problem had been widened to include the steel specialists at Firth-Vickers as well as the alloy team at High Duty Alloys, as a result Bristol's technical team were confident they would soon solve the problem, however they had been confident of solving the problem 'soon' for most of the decade so understandably concerns were still mounting. Taking all this into account it was a fairly easy decision for Air Ministry to kill off Taurus, removing it from the specifications then under draft and directing that Bristol's priorities should be Hercules and finally solving the sleeve valve manufacturing issues. With the engine pipeline re-ordered to their satisfaction, the Air Ministry could turn it's attention to the aircraft that they would hopefully be powering.
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Notes:
I did consider splitting this into two, but it's honestly not that long. Well not by Butterfly standards anyway. In any event it has a title I love dearly and I don't even mind if no-one else bar me gets it.
Those of you familiar with WW2 British aero-engines will hopefully be fascinated by the changes seen, those who have let their studies lapse hopefully found it enjoyable anyway. I tried not to get bogged down in marks and variants of the engines, just to be clear engines generally increased in power during their life as they got developed so nominal power is normally what the first variant produced, even if later ones produced more. As a handy rule of thumb an engine was expected to add ~250/300hp during it's life, some struggled to do that, others smashed it and doubled or more.
The trend towards clever not big engines is not something you see much discussed, yet I would argue it is a serious under-current. The Speed Spitfire project was OTL just too late, the engine was ready nice and early but they had to wait till Spitfire production was well underway before they could 'borrow' one for modification. In Butterfly the rush to get Spitfire into production (and stopping Supermarine building various crap flying boats so they had the capacity) has brought the timetable forward considerably, though at some cost to Coastal Command as we shall see in the next update.
I love the Rolls Royce Exe, it is a tour de force of brilliant engineering. It is also just too small and the best option would have been to kill it, being a X-24 sleeve valve it is fairly resource intensive compared to a 'simple' V12 Merlin, Lord Hives (RR Works manager) reckoned 275 Exe was the production equivalent of 1,200 Merlins. Now he was trying to get Exe killed and Merlin had been optimised for mass production by then in a way Exe hadn't, but even so you have twice the number of cylinders (even if they are smaller) and as mentioned later sleeve valves are more demanding in manufacture. That said I am trying to make plausible mistakes here so Exe lives and the FAA get 'their' engine, even if really they should just be using Merlins.
The many Kestrel variants are mostly things that were discussed, RR did look at Kestrel as a tank engine in 1941 but the Army wanted 600hp+ so they used Merlin instead to make Meteor. The RN asked about Kestrel/Peregrine for their MTBs in 1940 when they lost their Italian supplier, but ended up going with Packard. The RAF trainers used Kestrel Mk.XXX engines, which were older Kestrel blocks from biplanes given a refurb and de-tune, then pushed into service. Meadows did tank engines (*whisper* Covenantor) and the engine performed as promised it was just everything else that was awful, so I felt they deserved to get a good tank for once. We shall see what aircraft the Spanish Kestrel ends up in at some point in the not-too-soon future. The MoDC deserved a little win, even if Macmillan did once again overplay his hand.
OTL Trafford Park ended up a Merlin shadow factory, as befits a Ford factory it took ages to get going but once finally operational produced huge amounts of engines (400 a week at peak) most to chuck into Lancasters and Halifaxes as fast as the airframe could be built, all of them Series 20 as the line was too inflexible to be changed much. Government is no longer planning a tens of thousand strong heavy bomber force, and Ford UK is having a rough time of things as noted, so Trafford Park stays derelict for now.
The Phoenix sprint engine was the RR Crecy in OTL. Another absolute masterpiece of engineering, it was if anything too successful as the few times they looked at fitting a prototype into an aircraft (Spitfire, P-51, Mosquito) they concluded it had far too much power for the airframe to cope with. Overtaken by the jet engine of course and again the hindsight decision is scrap it, but instead the crazy gang at Napier get to play with it while Alvis try to make sure the sane ones focus on Sabre. The A-S Sabretooth Tiger never existed, they were took busy panicking about Deerhound being a disaster, but they have new competent management and honestly had the capability to do a small tweak to an existing engine while working on a new one, all they needed was a decent chief designer which they now have. Plus I like the name and thought A-S deserved a little success as well.
Finally Bristol and the cancellation of Taurus, it was just a horrible problem child for years. I spared us all a discussion of the clamp problems but briefly Taurus had a hairpin maneton clamp which never really worked properly and no other Bristol had that sort of clamp for long and not interesting reasons. As this was the clamp that held the two parts of the crankshaft together, it should be clear why a failure was always catastrophic. Killing Taurus will not really help with getting sleeve valves ready for mass production, that's a materials and finishing issue not a design one, but it will free up people to get Hercules running and de-bugged a fair chunk earlier than OTL, which will please the Air Staff greatly.
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