RAF's alternative doctrine and procurement between 1934 and 1940

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Some dead wood to cut + rationalization:
New 2-engined heavy bombers need to be able to hold a torpedo in a bomb bay: a 4-engined heavy bomber needs to have a bomb bay to hold two torpedoes. 1-engined bombers need to be trialed with an underslung torpedo.
That removes the need to have separate torpedo bomber types. The Botha debacle (1100+ engines and props invested at the end, plus a lot of other material, as well as man-hours) is thus removed, Blackburn can move on to make useful aircraft (Hampden, Wellington, what you have). Battle will need a better power-to-weight ratio to lift the torpedo, so now is time to install the Pegasus on it (saves ~500 lbs vs. Merlin III, can offer 130 HP more for take off).
 
I like to look at how things could have been done different with different decision. And try not use hindsight.
I may be using hindsight when I look at lessons from WW I that were forgotten or ignored at the beginning of WWII.

Somethings developed they way they did because in many cases you had to follow the chain.
It didn't do much good to try to build two stage superchargers in the mid 30s because the fuel wasn't going to make anywhere full use of them.

The Merlin (just using it as example, Pick R-1830 if you want) was limited to about 6lbs of boost using the original fuel and supercharger ( with a lower gear ratio and slower impeller it could use more at lower altitude). Now if you stick a two stage supercharger on it several things are going to happen using 87 octane fuel. If you try to get 6lbs of boost at say 24,000ft you are making a more heat in the superchargers and you cannon hit the 6lb boost limit without detonation unless you use a really, really big (read huge) intercooler system. You also have to look at the power being made in the cylinders. Instead of 1030hp at 16,000ft to prop with around 100hp going to friction and somewhere around 150hp (WAG) driving the supercharger you have the same friction, the same 150hp (or a bit less) driving one stage and now you have another 150hp or more driving the 2nd stage. So now you have about 900hp to drive the prop. The standard Merlin III was going to loose about 2% per 1000ft or give you around 900hp at 21,000ft without any extra 'stuff' hanging off of it.

Hooker did several things.
1, he realized that some of the formulas used to design superchargers had errors. This was somewhat masked by the low boost used and the lack of good instrumentation to correlate measured results to theory.
2. He straitened out the intake on the Merlin supercharger and got several thousand feet out of the rest of the design because the whole supercharger was more efficient. He got more compression from the supercharger while using less power to drive it and heating the intake charge less. Gets you to the Merlin XX and 45.

Now you can go to the 2 stage supercharger because you have a more efficient base supercharger and you are being given higher PN fuel that will give you higher performance.
P & W spent years trying to get a 2 stage supercharger to work and in 1938-39 they were using US 100 octane fuel. The performance they were getting in 1938-39 was better than the single stage supercharger but the cost was high.

Two stage engine was good for 1200hp at sea level, single stage engine was good for 1100hp at sea level
...............................................................1050hp at 17,000ft, .........................................................................950hp at 14,300ft

Single stage engine was about 200lbs lighter and didn't need the intercooler

see duct under the fuselage. It took a while to get the engine to be the one used the F4F.

Hooker probably could have helped them quite a bit but until you get 100/130 fuel you are not going to get a big increase in power over the single stage superchargers.
 
The central entry supercharger was not Hookers Idea. Rolls Royce was experimenting with it before Hooker joined the firm.
 
Is any more money being made available and if so when? More money earlier would enable more Battles and Blenheims, whether it would also deliver their replacements in a timely manner is more problematical. Now for some statements of the obvious.

We know the timeline, we know the designs and doctrine that worked, we know the real strength and capability of the Luftwaffe but say for example Germany, Italy and Japan align, the first two become nationalist but not expansionist until Japan decides to take South East Asia? Or the German attack on France in 1940 stalls? The USAAF and USN generally found the 0.5 inch machine gun an effective weapon in WWII, how about if they faced incoming B-17/24/29 equivalents? How about the self defending USAAF heavy bomber working if the enemy has fighters with only 2 or 4 rifle calibre machine guns?

The empty weight of the main RAF air targets, Bf109E 2 tons, Bf109G-6 2.7 tons, Fw190A-8 3 tons, Do17M 5 tons, Bf110C 5 tons, He11H-16 8.5 tons (the He111E-3 loaded weight was 9 tons), Do217E 9 tons, Ju88A-4 10 tons, He177A-5 17 tons. By using the Browning and wing guns the RAF more than doubled fighter firepower, Gladiator to Hurricane, less some loss due to harmonisation issues but the average size of the targets and so their airframe strength was also going up. The Bristol Fighter was one of the better WWI aircraft, a modern version, using a turret or some similar two man fighter must surely stand the same chance.

Consider how failure often teaches much more than success, we know what did not work because of what people tried, think of the various current ideas on better uses of the allied bomber fleet against targets that were not heavily attacked during the war.

Aircraft designs were becoming rapidly obsolete in the late 1930's and early 1940's as available reliable engine power around doubled to the 1,500 HP class, then performance somewhat unexpectedly plateaued as everyone had trouble with 2,000 HP class engines, high speed aerodynamics and the fall off in propeller efficiency with speed. And the sheer time to design, test and produce a new type given this. Understanding in late 1944/early 1945 the Mosquito by day and beginning at night was being exposed as becoming obsolete with the arrival of the jets. All the designs had their window where they were good, very good or the best, then the window closed. It is all moving targets.

When peace time stopped everyone ended up with their obsolete front line aircraft. They also had a great need for trainers, including advanced ones which the now obsolete types could help fill, the Lancaster Finishing Schools in Bomber Command being a extreme example, train on Stirlings and Halifaxes until a final transition to Lancasters. In the expansion of Fighter Command just after war was declared Battles gave the pilots experience with Merlin engines and retractable undercarriages while awaiting the fighters.

However air supremacy makes obsolesence obsolete. Air superiority almost as well. Or in other words how many Cubs and Austers as used in 1944 would have survived 1940 France. Given in May and June 1940 the Luftwaffe reconnaissance unit aircraft losses were close range 23%, long range 27%.

Production:
At least triple the average WWI development time and time to mass production allowance when doing forecasting. Look at common components, for example the York with its Lancaster engines, wings, tail and undercarriage. Ensure a general reconnaissance version and perhaps transport/paratroop version is developed of all the 2 and 4 engined bomber designs, enabling rationalisation of production, training and spares.

Development and time to mass production:
Engines take longest, Napier spent part of the Sabre development cycle tinkering to pass the test, not solving the basic problems. So more oversight seems required and more sharing of solutions earlier. Next time wise is airframes, ordering multiple prototypes and possibly pre production examples. Then comes armament, remembering all peace time stocks will be used in the first few weeks of any major shooting match. Development of new bombs, upgrading to heavier machine guns or cannon. A greater emphasis on electronics. More money for gas turbines earlier. Put more wind tunnels into service with higher speeds.

Training,
It seems in 1939 the RAF was running its training system flat out, regulars during the week then reservists on the weekend. Then war was declared, the reservists called up and training put under war zone restrictions. Pre war move some of the training system overseas, Rhodesia is a colony, Canada and South Africa would be uninterested but Australia and New Zealand should be agreeable. On declaration of war immediately accelerate the moves. (Hindsight: initially keep the fighter pilot training system running at capacity, limit the output of other aircrew if there are capacity issues)

Doctrine:
The basic objective of each branch of the armed services is to defeat their enemy opposite number. This can best be done by combined arms, the branches of the service having an agreed plan. While at the same time pushing the longer range navigation etc. needed for strategic bombing do regular theory and field exercises of joint headquarters exploring the abilities and limitations or airpower at sea and on land, more exercises like the mobile brigade one. In WWI aircraft did not have a big impact on naval war, nor did it do much to the enemy army beyond the front line. This had changed. Do the exercises even though the army had no plans for an expeditionary force until the 2 division idea in 1938. In per division terms the RAF provided about as many bomber and reconnaissance aircraft in 1940 to the BEF as it did to 21st Army group in 1944, but way less fighters and no mechanism to do joint planning or a coherent combined doctrine. Also note the main German breakthrough in 1940 was not in the BEF sector, imposing another layer between the bombers and targets.

Information:
Do more of the trials like where the obsolete aircraft were bombed to assess damage, expand that to obsolete factory equipment, rail tracks etc. Drop more real bombs in practice and recover the unexploded ones to find out why. Trials of explosives mixes and fuses. Similar for navigation trials, day and night interceptions, finding and tracking convoys, ships, warships at sea etc. Buy and examine the latest copies of other people's designs.
What to buy abroad, from components to whole aircraft? Cooperation between the friendly countries?
Overseas supply:
Comes down to what gaps are likely to be present at the probable war starting date, in 1938 it was advanced trainers and medium range patrol aircraft able to reach Norway from Britain. A definite requirement is foreign engine supply unless the changes enable British production of the required power and reliability levels to be increased. Against that is the US neutrality legislation, just as you really need the stuff the US stops supplying, plus the foreign exchange requirements.

The above list does not ask for much more money. Below the hindsight would enable savings to help pay for the extra stuff but also remember things like armour in fighters and more live fire exercises could wait until war is declared and spending limits are eased.

Electronics limitations, costs
Australian Archives A705 201/28/22 Part 1 p163
Cost of radar station in Australian pounds
5000 Site and accommodation and administrative buildings
1000 Technical buildings
7000 Equipment
2000 Power Supplies
3000 Communications (Say 10 miles of telephone line)
18000 Total
Or around one and a half to two single engine single seater fighter aircraft. The radio and radar fit of the P-61 was around $20,000, the B-29 $35,000, a complete P-51 around $52,000. To make the point more electronics will cost real money.

Hindsight,
The biggest direct losses to Britain in the early war period were to the U-boats and night bombing. Move the Whitleys to Coastal Command, using the mark V with Merlin engines, put a GR version of the Wellington into production in 1939/40 to replace the Whitley, give Coastal Command a higher priority. Build Beaufighters instead of Beauforts, the Beaufighters coming with provision for radar, underwing racks for fuel or bombs and under fuselage for torpedo, mine, bomb and fuel, able to be night fighters and a more survivable maritime strike aircraft while enabling one less design in production. Built the mark I Spitfire with mark VIII fuel tankage and allow for external tanks. Have Westland build the Seafire not the Whirlwind, replacing the Fulmar, given the extra fuel and drop tank capacity. Earlier Sabre and more so Centaurus fixes, perhaps to the point where the thin winged Typhoon (Tempest) switches from Sabre to Centaurus in 1943, enabling the end of Sabre production. The Barracuda designed from the start with a Merlin. Same for the Manchester, plus up the maximum weight allowed. A lower crisis response in 1940 when it comes to designs under test or entering production.

Know what gaps the US designs can fill, like day operation light and medium bomber, and cut back the effort on similar local designs until near the end of the war, the effort based on probable post war requirements not wartime.

Longer term outlook, a transport version of the Albemarle replaces the Whitley in production, dropping the non strategic materials requirement. Give the transport a rear fuselage loading ramp and thereby provide a versatile allied medium transport with self sealing fuel tanks, similarly the York in the large transport category but also with a tricycle undercarriage and loading ramp, coming into service in 1940/41, it keeps the British aviation industry in the transport business during the war which should help post war.

Better initial choices for shadow factory management, consider training courses for managers to help them cope with their suddenly expanding business. Napier gets quality control training in quantity.

Fighter tactics based on the pairs idea, better gunnery training including deflection shooting. Similar improvements for bomber and reconnaissance units, along with intelligence etc.

Pre war switch back to requiring leak proof rather than crash proof fuel tanks. More navigation aids like radio beacons, GEE. More realistic long range flying training. More and better reconnaissance. And so on.

And of course cancel or curtail a whole lot of what we know to be poor or not useful designs, tweak the ones that did work for earlier arrival, better performance and/or easier production. Engines, Airframes, Armaments.

All this on top of the things the RAF was doing right, production plans with reserves, training expansion schemes, ground controlled interception etc.
 

Well, in 1934-1939 the idea of using heavy bombers as torpedo bombers needs to be looked at long and hard. Using 4 engine bombers at under 100ft and at speeds barely over 120-150mph is really trading bombers for torpedo hits. Skip the torpedoes and just have the pilots crash into the ships. All it did was give you a big bomb bay you could use for other things.

The Botha debacle should have been seen by an 80 year old one eyed man with glaucoma while it was still on paper.
Take Blenheim as starting point, at 12,500lbs

add crewman and bigger bombload and extra "stuff".
Get weight up to 17,000-18000lbs
Scratch head at low performance calculations.
Tell Bristol they can change to the Taurus engine for more power.
Tell Blackburn, "sorry, no Taurus for you.....here is this nice Perseus engine instead of the Mercury, it has an extra 25hp for take-off over the Mercury, just make do"
Late Botha wound up over 12,000lbs tare weight and 18,450lbs gross.
just under 50% increase in weight for under 4% more power and the plane had higher drag.
The medium supercharged version of the engine did give about 21% more power at take-off.

We don't need the retrospectroscope to figure out how this ended.

If you want a Battle with a torpedo, just change the supercharger gear ratio. Merlin VIII as used in the Fulmar or the not produced R.M.1.M specification 1000-1080hp for take-off on 87 octane fuel.

It very strangely took a period of time to get the "torpedo bombers" engines that worked at low altitude instead of at 15,000ft.
one wonders what the intentions of the people that issued the specifications were???

The Botha was given the Perseus XA engine after a short period of time that cut the speed at 15,000ft from 253mph to 220mph cut the ceiling by about 5,000ft.
What it did do was give more speed at sea level and improved the rate of climb from 820fpm to 985 fpm (20% increase in rate of climb)
Amazing what putting a low altitude engine on a low altitude airplane will do

RR and Bristol had been making engines with no superchargers, low altitude supercharges (called medium) and high altitude superchargers (called fully supercharged for 12-15,000ft) for years before 1938. They knew how to optimized the engine for the altitudes they would be used at.

Of course if you want torpedo bombers you actually need torpedoes.
If you want a funding trick to sneak in extra light bombers then you don't need torpedoes and using engines that peak at 15,500ft for long rang cruise starts to make sense.
 
! Don't give Blackburn any work!

Sums it up...
I have, in the past, been one who is aghast at the Firebrand program but the brickbats are to be directed at the changes in requirements from the Admiralty. Blackburns themselves did a good job under the ever changing circumstances and the Firebrand went on to serve for six years as the principal anti shipping resource of the Home fleet tasked with sinking the major Soviet naval vessels. Being retained at home for that task despite the Korean War. Even to be fair to the Admiralty they asked for good in the future but knew they needed good enough now for fighters. Hence the retasking of the Firebrand once they squeezed their pre war request for Sea Hurricanes and Sea Spitfires out of the powers that be.

One might criticise their Skua but it was the worlds leading carrier borne strike aeroplane on it's entry. Of the Roc: well the customer came and asked for it and would pay so they did what they were asked to. Even though they pointed out that they had no capacity to actually make it so the customer had to shop around for another company to do the building.

Re the Botha. Yes it certainly had faults but Blackburns themselves said that it would be under powered and that the specified turret was an aerodynamic horror but, again, the customer insisted and Blackburn was a commercial company so did what they were paid to do. Had the Botha a pair of Taurus and the rudder blanking by the aero wobbling turret addressed we might be lauding the brave crews who struck at the Kriegsmarine in their Bothas so well in the face of losses and being the terror of the Italian Navy in the Mediterranean like the Beaufort IOTL.
 
The P.13/36 Spec that led to the Avro Manchester and HP Halifax, initially contained a number of requirements including the ability to carry torpedoes, which partially accounts for the long bomb bay in the Manchester as the indications are that they would be carried one behind the other.

Torpedo dropping requirement dropped 26 Aug 1937.
Catapult launch requirement dropped 4 July 1938
Dive bombing requirement dropped 11 Aug 1938 (the required 60 degree angle considered unobtainable)
Troop carrying requirement dropped 30 Jan 1940

It was mid-1937 that the Air Ministry were becoming so concerned about the RR Vulture that they decided the HP56 contender should become 4 engined. So HP were able to redesign their proposal by the end of the year, taking advantage of the lack of the torpedo dropping requirement to shorten the bomb bay in the redesigned HP57 Halifax. Construction of that prototype began in March 1938.

The main problem with torpedo dropping in the mid-1930s are the low speed and height limitations for dropping them (about 180mph & 70ft Max). The new Mk.XII torpedo was designed from 1935 which helped. But a lot of work was going on to improve dropping heights and speeds and it continued throughout WW2. These resulted in the Monoplane Air Tail. A consequence of the adoption of this device is that it precludes side by side carriage (the Mk.I version had a 50 inch wingspan and added to the length of the 16ft 3in Mk.XII torpedo).

The 1942 Mk.XV torpedo and MAT Mk.IV expanded the torpedo dropping envelope even further.

Such were the acknowledged risks involved with torpedo dropping that in 1939 work began to create a "stand off" torpedo type weapon. That led to the Toraplane and eventually Helmore

By 1947 the RAF had decided that torpedo dropping was so dangerous that the Brigand was re-roled as a light bomber.

Wellingtons, in the Middle East, and Hampdens, in Britain, were only switched to the torpedo bombing role in early 1942 due to a shortage of Beauforts to equip all the planned additional squadrons and the need to send squadrons from Britain to the Far East. Had Australian production started as originally planned the Far East requirement would have been met from that source.

A single engined Wellesley was used for torpedo dropping trials.


Note that both Spec B.12/36, leading to the Stirling, and P.13/36, leading to the Manchester and Halifax, called for "an aircraft that can exploit the alternatives between long range and very heavy bomb load which is made possible by catapult launching in an overload condition".

This requires some clarification. This was an era of grass airfields which were often wet enough to limit operations and/or the take off weight of aircraft (the first concrete runways on RAF airfields didn't appear until late 1938). So a scheme was hatched to assist them to get airborne without incurring the cost of massive concrete runways on every bomber airfield in Britain.

This was not "catapulting" as thought of in the context of aircraft carriers where the catapult physically pulled the aircraft into the air.

The task given to the RAE was to come up with a scheme to "assist" a heavily loaded aircraft to get airborne. The ultimate goal was to "launch" a 64,000lb aircraft at 120mph in a 50mph crosswind. The trial set up they came up with consisted of firstly a turntable. An aircraft aircraft would be loaded onto a trolley on the turntable, have its tail raised into a flying position and be prepared for flight. It would then rotated to face a permanent trackway laid across the airfield. That trackway had rails on which the aircraft main wheels sat. The only concrete involved was for the foundations on which the steel rails sat. The crew would board the aircraft, start the engines, and take off. With the aircraft already in a flying position, and without the added friction from the grass, take off at heavy weights from the trolley was intended to be achieved in about 1300-1400 yards with the trolley then being arrested and returned to the starting point for the next aircraft.

The RAE referred to this set up as "Direction Controlled Take-Off" or DCTO. In 1940 an HP Heyford aircraft was modified for tests and 2 launches were carried out. That was followed up in 1942 with a single launch using a Manchester bomber at 31,000lb ( some sources say July 1941 for the Manchester test at 38,000lb). Preparing the aircraft was however a lengthy task.






One effect of planning for this was that aircraft structures had to be strengthened to cope with the stresses involved. Not sure how it affected the Stirling, but I have found references to say that the first 20 Manchesters were too advanced in their construction when the requirement was dropped in July 1938, to be modified. But I don't know if subsequent aircraft were. Maybe this extra strengthening accounts for the Lancaster's ability to carry a 22,000lb bomb come 1944. It is however probable that George Volkert was able to take advantage when the HP56 was redesigned as the HP57 during 1937/38 because construction of the prototype had only begun about 4 months earlier.

So does a lack of realism about the increasing size of aircraft in 1936 and penny pinching on the infrastructure to operate them from for another 2-3 years ("cheap" catapult" v concrete runways) combines to hinder aircraft performance?
 
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Agreed. In many ways the Firebrand was a victim of wartime circumstances.

Having originated as a Hercules engined paper proposal (given the timescale it can have been no more than an outline of what Blackburn thought possible) in Dec 1939 in response to rapidly changing Admiralty requirements. It was selected for development in Jan 1940 because it looked "promising". By Aug 1940 a full Spec was written around that earlier proposal for a 400mph Sabre engined fighter, but with stringent, perhaps too stringent, carrier take off and landing limits and an order was placed for 50. Even with all the wartime delays it first flew (Feb 1942), just over 2 years from that very first paper proposal being accepted. That is not a bad development time even though everyone hoped it would be quicker.

Unfortunately it encountered two problems:-
1. In late 1941 the Admiralty had finally got its hands on the Spitfire denied it in 1939. First deck landing late Dec 1941. Seafire squadron service from June 1942. Prospect of several hundred quickly.
2. It was short on the promised performance (355mph v 400mph anticipated) I.e no better than the Seafire.

So what is the Admiralty supposed to do, with two more prototypes nearing completion and series production aircraft already on the line? So it made the best of a bad situation. It found a new role for the remainder on order. Expanded the centre section to allow carriage of a torpedo in the Mk.II.

As a "torpedo bomber fighter" it represents a considerable advance in the TB role when compared to the Barracuda which entered production in April 1942 and squadron service in Jan 1943. That role was becoming ever more dangerous (see Channel Dash, Midway and Beaufort losses in the Med in 1942). The next time the Admiralty got round ordering a new torpedo aircraft as a Barracuda replacement was in Dec 1943 to Fairey under Spec O.5/43 for what flew in July 1945 as the Spearfish.

Then what happens. Those nasty men at MAP decide in early 1943 that the Typhoon should have all the Sabre engines. Right decision but one in which the Admiralty and Blackburn had no say. So Blackburn are forced into another redesign to a revised Spec S.8/43 issued Oct 1943 and have a Centaurus powered Mk.III flying by the end of the year.

So from an initial order for 3 prototypes & 50 production aircraft back in 1940 the RN got:-
Prototypes - 3 (incl 1 rebuilt as a Mk.II Feb/Mar 1943 after crashing)
F.I - 9 whose build was too far advanced to be completed as Mk.II plus 2 rebuilt as Mk.III prototypes
TF.II - 12
TF.III - 27 (delivered from Nov 1944 to May 1945)

The real issue for me is not so much the decision to use the Firebrand as a torpedo fighter or even the change to the Centaurus engine but the delays in actually building these 50 aircraft, even the Mk.I, and especially of 12 months in going from prototype Mk.III in Dec 1943 to the first production aircraft in Nov 1944. It seems that an awful lot of problems had to be overcome or there was a lack of priority being given to the whole project. Probably both.

Eventually the improved Mk.IV from a new order began to flow in May 1945 following on the heels of the last Mk.III, with the first operational squadron, 813, forming in Sept 1945. Admiralty plans in 1945 envisaged the first two squadrons on light fleet carriers by mid-1946. 813's postwar service was marked by serviceability issues and a shortage of spare parts. They never operated from the light fleet carriers. That may be due to their take off run, when loaded with a torpedo, of 680ft, which would have necessitated the use of RATOG.

Having had some initial experience with the single seat TF concept, the RN followed up by issuing Spec S.28/43 in Feb 1944 and then S.10/45 for a thin winged Firebrand which emerged in 1947 as the Blackburn Firecrest (2 prototypes only flown). Single seat torpedo aircraft was clearly the way to go as the USN demonstrated later with the much better Douglas Skyraider and Martin Mauler.
 

Better start cranking these Hurricanes pronto, Gloster. Not having to produce 200 Henleys is a help from late 1938/early 1939.


Unions in the UK (and elsewhere, but not in the USA) are trade-based, not location-based. Brand new machinery will help greatly at Westland and Boulton-Paul.
Army cooperation aircraft is a topic of it's own.


It will still take off, no worries.
 
It is worthwhile taking a moment to consider the political background and attitudes around the start of the 1930s which does have an effect on the starting point of this discussion.

Disarmament
A Conference for the Reduction and Limitation of Armaments ran from February 1932 to November 1934 under League of Nations auspices before falling apart. One of the things it sought to do was to abolish Offensive Aviation.

One of the subcommittees addressed proposals for limiting construction programmes, payloads, and operational ranges of aircraft.

So how is this relevant to the 1934-1940 period? Well 1932-1934 is when the Specs were issued for aircraft like the Battle, Wellington, Hampden, Whitley etc. In ""The British Aircraft Specifications File" in relation to Spec B.9/32 issued in Sept 1932 that led to the Hampden & Wellington is this comment:-

"Four designs were considered against Specification B.9/32, with contracts awarded to Handley Page and Vickers. Both firms made representations to the Air Ministry about the weight limit imposed by the League of Nations, and the insistence that the tare weight of the aeroplane be adhered to as laid down in the specification. This requirement limited the structural weight and power of the engine. An agreement was reached."

In the Warpaint book on the Wellington this is noted as "outmoded thinking by the Air Ministry" and was "overcome".

"The Vickers team circumvented this restriction and the tare weight of the Wellington rose from 6,300 to 11,508 lbs between the time that the tender was first submited and the date on which the prototype first flew in 1936."

So over 3 years elapsed from issue of the Spec until the prototype Wellington & Hampden flew. Then revised Specs for both were issued in Jan 1937 for the production versions ordered the year before. And a Wellington Mk.I weighed 18,556 lbs empty. A Hampden empty weight was 12,764 lbs. How much redesign effort was expended along the way with these aircraft before we get to the next generation arising from B.12/36 and P.13/36 that led to the Stirling, Manchester and Halifax?

I haven't yet been able to track down any detail on these League technical committee limits to judge what other influences that they may have had on aircraft design.

League of Nations
In March 1933 Japan left the League of Nations. Hitler came to power in Jan 1933 and Germany left the League in Oct 1933.

Who is the enemy?
Until 1934, the RAF saw France as the potential enemy and sought to match it in numbers. That only changed at some point in 1934, when Germany becomes the focus of attention.

But the range characteristics for an aircraft needed to bomb France are different from those needed to bomb Germany. So B.9/32 called for a range of 720 miles at 15,000ft (extendable to 1,250 miles with auxiliary tanks). The Wellington Mk.I had a range of 2,250 miles at 15,000ft and the Hampden 1,720 miles.

Other
I found this study on RAF planning in the 1930s which I found of interest.

Some of this is also relevant to some of the other threads running about the RAF in the 1930s.
 
Some things not discussed here, that will require change in the RAF's doctrine:
- long-range fighters (even if not declared as needed for Europe, long range is needed for Asian and African commitments - this might be a loophole?)
- army cooperation aircraft, including the fighter bombers, or perhaps let's call them 'fast frontline bombers'; proper light transport aircraft for army (sorta pre-An-2, or something like Norduyn Norseman, or someting like Bellanca Aircruiser); small utility aricraft (rather a Storch equivalent, than a Hs 126 equivalent) for artillery spotting, frontline reconnaissance and to shuttle around important people
 
For the RAF idea of the situation.
In particular for this topic, from

The flying training section and "The Expansion of the RAF 1934-1939"

The above requires a surplus of fighters before they can be allocated to the sort of activities that did happen in 1918, along with the discovery of how survivable bombers were in contested airspace, even relatively close to the front line, yet the allies did field large numbers of light and medium bombers usually doing medium altitude level bombing, the fighter bombers adding to that firepower. Given the 1940 doctrine was more about targets behind the front line the use of Battle and Blenheim level bombers were the intended equivalent of the later war A-20/A-26/B-25/B-26 operations. The 1940 doctrine had plenty of peace time
assumptions, like accuracy and bomb damage expectations, which proved incorrect, but the big gap was intervention around the front line beyond what the Lysanders would do. The RAF actually sent relevant the bomber and reconnaissance assets to France in 1940, but with faulty doctrine and crucially not enough fighter support.

The USAAF did not really like the Norseman, the medical people took advantage of that in 1944 in France to set up their air transport system. Pre war and even Overlord planning did not envisage ground fighting taking place very far from operating rail heads, expecting lots of 1918 style steady advances, so no major need for a big "local" air transport system. No one in the 1930's had the knowledge to come up with a scenario of coping with a heavily damaged rail and port infrastructure with the front line up to hundreds of miles in front of working rail heads. Also air transport is expensive. One benefit of the desired allied airborne army was lots of transports usually available for supply purposes, it is unlikely in Europe at least that big a transport force would be created without the paratroop units being in theatre.

The Lysander was meant as the artillery spotter, local reconnaissance, light attack aircraft and short hop shuttle, remembering the more people you want inside the bigger the aircraft. In any case as was shown the light aircraft in production for civilian uses could be easily adapted and produced. In peacetime it is usually better to spend the money on the bigger aircraft and more combat types, since transports etc. are rather like small ships in the navy, hard to find money for pre war and usually the simplest requirement to fill during the war by cranking up the relevant civil production lines.

Also consider the wartime expansion of the definition of flyable weather, the more often the aircraft could fly the more useful they became, no one pre war had the information to envisage what the 9th Air Force did. Put a high quality radar near the front line and use it to guide aircraft onto targets in poor to bad weather, ground controlled ground attack, similar for the use of radio and radar based bombing aids. Pre war it was all visual bombing and the air forces were all well aware of how often the weather allowed that. Look at all the low activity due to weather, effectively rest, days during the Battle of Britain.
 
It will still take off, no worries.
Well, trying to take-off In a Hurricane with about under 700hp going to the Prop (with the wrong pitch) is a lot different than taking off with over 1200hp and prop with a much better pitch angle. You can get some of the early planes in the air but you are going to have more accidents.
This is thing with some of the "Just do it earlier" scenarios.
Hawker proposes 4 cannon Hurricane in 1937, Assume they could actually build first ones in 1938 or 1939.
Differences between early 1939 and late 1941 include.
Change from 87 octane fuel to 100/???
Change in propellers.
Change in the size and border obstructions on many of the airfields.

And it is not just taking off, coming in in bad weather/poor light the newer planes had a lower commit threshold. If something wasn't right they had a bit more time to decide to land or go around.
 
Some things not discussed here, that will require change in the RAF's doctrine:
- long-range fighters (even if not declared as needed for Europe, long range is needed for Asian and African commitments - this might be a loophole?)
We are covering 6 years or so.
In the early years you are trying to get enough aircraft to equip around 40 more squadrons (of all types) plus reequip many of the existing squadrons.
Historically the British just pushed older aircraft eastward.
For fighters this meant Gauntlets pushed older fighters out to the mid east and far east. Gladiators pushed Gauntlets out to the east and the older fighters were either junked or became trainers. Gladiators were sent east when they had enough Hurricanes at home and the Gauntlets became local trainers/etc.

The roughly 225 Gauntlets equipped, at times, 15 RAF squadrons and 4 Aux squadrons. Sometimes it was for less than a year. 3 squadrons equipped with Gauntlets in 1936 were reequipped with Gladiators in 1937 for example and some of Gauntlets were handed to newly formed up squadrons to, in effect, be operational trainers while waiting for the 8 gun fighters to show up. Of the 3 squadrons that got Gladiators one got Hurricanes and two switched to Spitfires. The Hurricane squadron also got Spitfires.
It wasn't until 1939 that Gauntlets were sent to the mid east, No 6 squadron in Palestine and No 33 and 112 Squadron in Egypt/Western Dessert.

Any high performance (Merlin powered) fighter you can come up with (or even a monoplane Mercury powered fighter) that you could send to the mid east would only come at the expense of fighters planed for the British Home front.

As for the escort fighter in general:
Now in this period we have several changes in what was possible and what was not possible. Bear with me here
In 1938 with Hurricane production established we have an opportunity to build an escort fighter.
We buy some American propellers, we jam an extra 20-30 gallons in the Hurricane, and we hang a couple of small drop tanks under wings.
AND we have a solution to escorting bomber XXX to the German border and fighting the BF 109D with Jumo 210 engine.
We need the American props to get airborne with the greater fuel load.
Problem is the unsporting, tricky Germans stop building the 109D 1939 and start building 109Es with DB 601 engines. Ability of the Hurricane I to fight/defend the bomber groups over Germany against 109Es is questionable in 1939-40. (even with new British made props).
Spitfires are being built in lower numbers than Hurricanes and are needed for home defense until production can be ramped up considerably.
The Defiant didn't go into production until Dec 1939 (1st delivery production started earlier) so canceling Defiant production does nothing in 1939 and not a whole lot in 1940.
The Roc was good for around 133 planes starting in April of 1939 and perhaps without trying build both the Roc and the Defiant prodcution of something else could have been ramped up sooner.

Once you have Better Merlins than the III and better than 87 octane fuel and have the Rotol Props in number, the escort fighter becomes a lot more possible using the Spitfire airframe. Still not a good to use Hurricanes.

However it may still requires a change in doctrine. Like for much of 1939 the British were not bombing the German production centers, which were around 250 miles away from possible forward British home bases (but overflying neutral countries)but were trying to bomb the German fleet which requires either different forward bases and/or flights of another 40-60 miles each way.

Target selection and routes from Britain to German targets got a lot easier in May-June of 1940 but try to predict that in 1938-39.
the British flubbed the whole army co-operation aircraft thing rather badly. So were many other nations.

But also consider that the British in 1938 or so (into early 1939? ) were only thinking of a 2 division expeditionary force. The British needed a lot more than just different types of aircraft to support the 10 divisions of troops eventually deployed. A number of British divisions were not even trained when they went to France and were trained in France.

This was part of the panic at the air ministry/war office with keeping Westland making the Lysander over the winter of 1939-40. They sent 4 squadrons in Oct 1939. How many more squadrons were sent is subject to question as they wound up with 175 aircraft in France ( enough for nearly 10 squadrons?) and these were MK IIs with Perseus engines. Many of the MK Is had been shuffled off the mid (or far) East.

And again, effective army co-operation requires not just faster, better armed aircraft but better selection of targets (point of effort) from ground commanders and better communications. British close support in the desert was helped by ease of spotting in the desert.


Maybe a US training center but gives the idea. Lack of vegetation and buildings means vehicles stick out like sore thumbs and planes follow tank/wheel tracks in the sand for miles (let alone the dust clouds) in case the vehicle crews did get tricky.

Didn't mean it was easy but but anything that shortened the learning curve was a help. If you are trying to start a doctrine/tactic use anything you can to get results to get established.



Local air transport is another subject but it can only be done at the expense of training aircraft.

3 seat DH Leopard Moth, the wings fold back.

But if you are building these then you are not building 8,800 Tiger Moths ( used the same engine for one thing)

British had several light aircraft that would have been suitable

6 seater with two 205 Gypsy Queen engines but again, there may have been production priorities.
 
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to expand on the above a bit. In Jan 1935 the British had 14 Fighter Squadrons at home.

Eight squadrons with Bristol Bulldogs IIa's

3 Squadrons with Hawker Fury I's with 117 built

In 1935 orders for another 23 Fury II's (more powerful engine) were placed with Hawker and another 89 built by General Aircraft Ltd, Hawker being rather busy.
Fury II's replaced/supplemented the Fury Is in No 25 squadron and equipped 3 additional squadrons in 1937.

The Hawker Demon equipped the last 3 squadrons.


The early version did not have the "turret". The Demon however points to some of the problems that started happening with the British procurement.

When the parent Hart bomber went into service it was discovered that the Standard Bulldog couldn't catch it or only could catch it with extreme difficulty, Which lead Camm with his modesty to claim that "to set a Hart to to catch a Hart". Six "fighter" Harts had been built after the first prototype Hart bomber had been modified into a fighter.
The "Hart" fighters were equal in maneuverability to the Bulldog and were faster and climbed better.
The Bulldog simply couldn't do the job that was required, to be fair it was old and first flew 1927 and the lack of cowling for the engine certainly didn't help.
A few more squadrons of Demons were ordered to have something a bit better than the Bulldogs and to get them in a hurry.
Instead of ordering more Fury's the RAF issued a requirement for the F.7/30 or rather used it's ongoing development (it was supposed to supply a 4 gun fighter with a 250mph speed which does make the Fury look rather antiquated) however the Air Ministry insisted on the Goshawk engine which doomed the whole generation of fighters designed around the specification. The world was heating up in 1935-36 and Several squadrons or flights were issued Demons in the Mid East in Egypt, Malta and Palestine.
Meanwhile specification 8/34 had been drawn up for a better Demon with the "turret" and after some modification it resulted in specification 40/34 with a more powerful Kestrel and transfer of production to Boulton Paul (Frazer-Nash was the maker of the gun mount), for 106 aircraft, only 61 of which had the "turrets"

By the time of Munich crises in 1938 Demons were equipping 8 squadrons of the RAF. Somehow the start of the Demon saga of it being a quicky solution to the obsolete Bulldog crisis was forgot and the "need" for a two seat replacement fighter combined with the enthusiasm for the 4 gun power turrets and no deflection shooting all combined to bring about the Defiant.
The later contract for the Fury II's was to help fill out squadrons when the F.7.30 aircraft all dropped into the toilet. The Gauntlet wasn't what the RAF wanted in 1934/35. It was it could get to replace the Bulldogs.
The Goshawk engines were so late being delivered that Hawker's entry ( a private venture) that the Gladiator was declared the winner.

The RAF was in a deep hole and needed planes that could at least keep up with foreign planes that were equipping foreign squadrons in 1936-37 and provide training for the pilots.\ and ground crew of the forming squadrons. The New planes (Hurricane and Spitfire) would take-over and be the future but until they got there the RAF something to replace the old Bulldogs which were nowhere good enough to stop any foreign attack. The Bulldog wasn't even 10mph faster than a Ju-52. The Ju-86 with diesel engines could cruise at fast as the Bulldog could fly at top speed (and a decent guess as to speed could be made looking at the times the Airline schedules were posting.
 
We are covering 6 years or so.

Local air transport is another subject but it can only be done at the expense of training aircraft

But if you are building these then you are not building 8,800 Tiger Moths ( used the same engine for one thing)
8,800 was total Tiger Moth production worldwide between 1931 and sometime postwar when overseas production ended. Over 2,800 of those were built overseas. And 3,400 were built 1941-45 by Morris Motors after DH transferred production to concentrate on Mosquito production.

Pre-war production at home and overseas totalled 1,424.

Even adding the Miles Magister trainer, produced from 1937, it only adds another 700 or so to the total by the outbreak of WW2.

But without these and other types used as trainers for pilots, navigators and radio operators in the 1930s there is no expansion of the RAF.
 

One of the many clever things Rolls Royce did was to rebuild older Kestrels into Kestrel XXXs for the Miles Master thus conserving production capacity for Merlins.
Here are some photos of Miles Master production
 
This book discusses RAF prewar procurement in great detail
Expensive but well worth it in my option.
Sinnott's PHD thesis which is the basis of this book is available online somewhere
 
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This book discusses RAF prewar procurement in great detail
Expensive but well worth it in my option.
Sinnott's PHD thesis which is the basis of this book is available online somewhere
Hi
For those interested there are quite a lot of books (let alone articles) available on British Air Policy, procurement and manufacture prior to and into WW2. These include:
'British Air Policy between the Wars 1918-1939' by H. Montgomery Hyde.
'The Beginnings of Strategic Air Power, A History of the British Bomber Force 1923-39' by Neville Jones.
'The RAF and Trade Defence 1919-1945, Constant Endeavour' by John Buckley.
'Strategy for Victory, The Development of British Tactical Air Power, 1919-1943' by David Ian Hall.
'The Eye in the Air' by Peter Mead.
'Industry and Air Power, The Expansion of British Aircraft Production, 1935-1941' by Sebastian Ritchie.
'British Aviation, Widening Horizons, 1930-1934, by Harald Penrose.
'British Aviation, Ominous Skies, 1935-1939' by Harald Penrose.
'Shadow Factories, Britain's Production Facilities During the Second World War' by David Rogers.

For the overall problems of British Defence Policy pre-war then there is from the OH 'Grand Strategy Volume I' by N. H. Gibbs, this does illustrated the changes in policy in the period due to changes in the world political situation and the knock on effects of procurement policy for the three armed forces (probably very useful read for those with 'alternative' ideas and their probable impact on the wider picture).

For naval matters there is the two volume 'Naval Policy between the Wars' by Stephen Roskill, Volume 1, subtitled, 'The Period of Anglo-American Antagonism 1919-1929' and Volume 2, 'The Period of Reluctant Rearmament 1930-1939'.

There will be plenty of other publications on the matter.

Mike
 

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