British 1936-42 purchase options, logistics and export/import of military hardware

tomo pauk said:

The RN's 6pdr is not a direct replacement for the Army's 6pdr, but a gun that should've been manufactured instead of the 2pdr. Thus, it looks splendid.
Instead of the Army's 6pdr, they need to start designing the tank-going 3in gun.

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FWIW, you're in esteemed company, sort of. A A.G. Williams suggests in AN ALTERNATIVE 1930s BRITISH TANK GUN to adopt the naval 6pdr ammo (with slight changes), but to design a new gun around it to take advantage of higher pressures made possible by contemporary propellant. With a steel core APCR AP performance estimated to be slightly better than the 2pdr, but substantially better HE. And later on as the steel core APCR runs out of steam, it's possible to introduces a tungsten core APCR with something like 50% better penetration. And substantially more compact than the historical 6pdr AT gun and ammo, so might better fit into early war tanks.

z42 said:

FWIW, you're in esteemed company, sort of. A A.G. Williams suggests in AN ALTERNATIVE 1930s BRITISH TANK GUN to adopt the naval 6pdr ammo (with slight changes), but to design a new gun around it to take advantage of higher pressures made possible by contemporary propellant.

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Tony starts out with the ww1 vintage gun
Not that I disagree with his suggestions there.

z42 said:

FWIW, you're in esteemed company, sort of. A A.G. Williams suggests in AN ALTERNATIVE 1930s BRITISH TANK GUN to adopt the naval 6pdr ammo (with slight changes), but to design a new gun around it to take advantage of higher pressures made possible by contemporary propellant. With a steel core APCR AP performance estimated to be slightly better than the 2pdr, but substantially better HE. And later on as the steel core APCR runs out of steam, it's possible to introduces a tungsten core APCR with something like 50% better penetration. And substantially more compact than the historical 6pdr AT gun and ammo, so might better fit into early war tanks.

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That is a good start, however in theory the penetration is proportional to the energy per unit of target area.
This is only good near the muzzle as shape of projectile and sectional density affect things with distance.
Mr. Williams uses the comparison of the German short 5cm gun to the 57mm gun in the 2nd paragraph.
50mm is close to 57mm right? Maybe is the real answer.
The 50mm is trying to make a hole 19.63 sq cm in area
The 57mm round is trying to make a hole 25.51 sq cm. or 29.9% bigger.
And do it while only starting with 14.1% more energy.

Now for a little more back story.
a 40mm hole is only 12.56 sq cm and the 2pdr shot at 853m/s has 392 Joules of energy.
This gives it 23.4% more energy per sq cm than the hypothetical 6pdr ammo full bore
Granted the 2pdr will loose penetration quicker at longer ranges.
BUT the 2pdr shot in example is the crappy, uncapped super simple, cheap shot.
Mr Williams wants to use a rather refined composite shot (more refined than most of the WW II APCR with more parts to assemble.
Basically, using a steel penetrator in the APCR MK I shot we are firing a 40mm penetrator at about the same speed as the 2pdr fires it's shot which means unless you use a lot longer penetrator body you are going to have the same energy. The outer shell body (aluminum?) is stripped away when the round hits and only weight of the penetrator counts.
Now you have the light weight 57mm APCR projectile fighting the air resentence so it is going to have worse penetration at long range than the standard 2pdr if you fire them at close to same velocity.
And as far a shape goes. Once the British got their thumbs out of their butts and designed an APCBC round (Pre WW I technology) the more streamlined shape allowed for 15% more penetration at 1000yds than the 2pdr HV shot and and 45% more at 2000yds. Unfortunately for the British troops this wonder of modern technology (1912?) didn't show up until 1943 which was too late to make any difference to the tank battles in NA.

For the British you not only have to select a decent gun (and the 2pdr was plenty decent in 1938-1940) you have to convince the treasury to spend money on decent ammo. Unless you can do that in 1938-39 all the 'trick' ammo in the world is going to sit on the experimental laboratory's shelf.

BTW the German 37mm AT/tank gun used a round that had 200,000 joules compered to the British 2pdr early ammo of 338,000 joules.
The German short 50 only had about 7% more power than the early British 2pdr ammo per sq cm of target area.

I would also be a little leery of trying to use widely differing projectile lengths though the same rifling twists. Extra long projectiles need more twist to keep the projectile stable.
Short high velocity projectiles can use a lot less twist.

tomo pauk said:

Bristol 2-engined aircraft: either have them be more ambitious, or have them be 1-engined instead. A keen eye needs to be had towards the most recent advances in airfoils in both cases.


A 'more ambitious' branch:
- Blenheim needs to be designed for a 2000 lb bomb load (alternatively a torpedo to be carried) fro the get-go.
- Beaufort needs to be designed for a 4000 lb bomb load, otherwise the Hampden is the type to be produced, not the Beaufort.
- Beaufighter - emphasis on performance, that means the aircraft need to be much smaller, talk ballpark of the Bf 110.
-

The 1-engined approach:
- The not-Blenheim to be sorta Dauntless.
- The not-Beufort to be size & weight of the Henley.
- The not-Beaufighter to be size of the F6F Hellcat (perhaps a bit smaller).

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The problem here is that the Blenheim and Beaufort were not fast enough. They needed more power, not fewer engines. The Beaufighter was brought into service quickly because they used Beaufort wings and tail. Would a design from scratch have been available for the night blitz? It was quick because they switched to the Hercules engines. The Beaufighter was successful to some extent because the British recognized that it was not a dogfighter. The Bf110 was useless when it went up against good single engined fighters.

The Hercules was small for a single-engined fighter radial, or for a single engined light bomber. It might have worked out in a fighter designed to be as small as possible, like the Fw190. The R2600 was not big enough for the Hellcat. The Hercules was smaller.

It is too bad the British lacked an airframe suitable for the Centaurus. I have just read By Jupiter, by Bill Gunston. Roy Fedden had plans to manufacture Centauruses in Montreal Canada in 1940. Unfortunately, there was no immediate demand. They would have made good substitutes for the R3350s that were burning up B-29s.

Howard Gibson said:

...They would have made good substitutes for the R3350s that were burning up B-29s.

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Politics excepted.

Shortround6 said:

Basically, using a steel penetrator in the APCR MK I shot we are firing a 40mm penetrator at about the same speed as the 2pdr fires it's shot which means unless you use a lot longer penetrator body you are going to have the same energy. The outer shell body (aluminum?) is stripped away when the round hits and only weight of the penetrator counts.

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Using a steel penetrator in the APCR Mk1 shot on the 2pdr gun means that penetrator is perhaps 25mm of diameter, like what the French used o their short 37mm. Since that means the shot is lighter, it will gain a lot of extra MV. French have gotten 600 m/s with the 390g 'APCR' shot there, vs. the old 500g AP shot doing under 390 m/s.
Penetration went up considerably, from 12mm at the muzzle for the old shot to about 20mm at 400m @ 35 deg.

Shortround6 said:

For the British you not only have to select a decent gun (and the 2pdr was plenty decent in 1938-1940) you have to convince the treasury to spend money on decent ammo. Unless you can do that in 1938-39 all the 'trick' ammo in the world is going to sit on the experimental laboratory's shelf.

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HE_capabilty multiplied with AP_capability = how good is a tank gun.
Army can make a decision to go with more substantial gun well before 1938, and that does not have to be the low MV 6pdr from ww1.

Howard Gibson said:

The problem here is that the Blenheim and Beaufort were not fast enough. They needed more power, not fewer engines.

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What kind of engine do you suggest for the Blenheim in 1936, or for the Beaufort in 1938?

Howard Gibson said:

The Hercules was small for a single-engined fighter radial, or for a single engined light bomber.

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Depends what one wants. A 400 mph A/C? 350 mph? 320 mph max, like what the historical Beaufighters did most of the time? Ability to mix with Axis best, or that is not a requirement?
And what that aircraft is supposed to do - intercept enemy bombers (day or night or both), at how log a range, does it need to lug some bombs/rockets/torpedo? Sacrifice performance in order to get a lot of them, or make a small numner but with high performance? How good is the company when it is about really fast aircraft in the last, say, 10 years?

Howard Gibson said:

It is too bad the British lacked an airframe suitable for the Centaurus. I have just read By Jupiter, by Bill Gunston. Roy Fedden had plans to manufacture Centauruses in Montreal Canada in 1940. Unfortunately, there was no immediate demand. They would have made good substitutes for the R3350s that were burning up B-29s.

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Typhoon/Tornado was there for the Centaurus.
Unfortunately, Roy Fedden would've been probably do much better if he designed better superchargers for Hercules, Pegasus and Mercury, than the 1940 manufacture of engine that was probably flight-ready in 1942?

Preventing the fall of France would require a major upgrade of allied army command and control plus much better training (plus AA guns) for reserve divisions to handle concentrated air attack. There is little the British can do in 1940 even if there was a combat ready force the size of 21st Army Group, it would need 2nd TAF as well at least (including things like radars and airbase mobility). France in 1940 was a form of proof the bomber would always get through, without adequate warning the defenders could not stop the Luftwaffe from carrying out a systematic plan of battle field support and interdiction with acceptable losses, on top of restricting allied army daylight mobility.

As people have noted starting in 1936 means a lot of better preparation is basic production capacity, registered unemployment was 1,710,000 in June 1938 and 1,270,000 in 1939 and 645,000 in June 1940, plenty of people available, the finance needed to employ them small compared with the 1945 government debt levels. Basic research, as noted, more factories with trained staff, aerodynamics, gas turbines, all the usual suspects. Do the research and development earlier and more extensively, however apart from obsolescence actually building stuff has limits, in 1936 about 5% of the western world merchant ship tonnage was laid up, better than the 20% or so in 1932 but not encouraging new ship building. Doing conscription without having the equipment for the new units would be counter productive. Pressuring the rest of the Empire to do similar defence expansions.

Minor note, pre war the flying schools worked on regulars trained during the week, reserves on weekends, declaration of war saw the reserves called up and the schools choke on the numbers. Sort that out at least for fighter pilots pre war. Put the 0.50 inch Browning into limited production in early 1940, if nothing else the USAAF will love you for it.

The key is to have any required item in production by April/May 1940 at the latest, after that delays of up to 2 years can be expected. The need for airpower will hurt the chances of obtaining suitable engines in numbers for 20 to 30 ton tanks.

Things like updated explosives and fuses, ordnance in general, fuels and other basic equipment that will only go into mass production when war occurs. Doctrine, speeding up decision times especially for the army, ensure the British Army armoured forces employed combined arms tactics, an area it largely shunned until as late as 1944, made obvious by the early Armoured Division "Support Group" name, size and equipment. Tank units did do combined arms, armoured ones did not. In mid 1942 in the desert an experienced British officer was given a unit of the new 6 pounder AT guns as part of his command and went into battle wondering what to do with them, not noticing how the Germans would incorporate AT guns in attacks. Yet the much maligned Portee for the 2 pounder gave the army the chance to do offensive anti tank actions. Understand units in a desert environment need more anti tank capacity at least than ones in Western Europe or a jungle, and probably more light AA. Understand the British Army in general had to reach a higher level of command for equivalent firepower compared to other armies, Bren versus MG42, 2 and 3 inch mortars versus 81mm, 25 pounder versus 105mm. This means better communication links and delegation of responsibilities, something achieved in the artillery area.

WO 169/3861 (Eighth Army) G(AFV) Branch dated 'End Sept.' [1942] headed "Tank Overhaul Programme." It gives the overhaul mileage limit/annual mileage rate/time in workshops for overhaul (weeks) as:
Crusader 1200 / 3000 / 8
Valentine 2500 / 3000 / 8
Matilda 1000 / 3000 / 8
Stuart 3500 / 3000 / 4
Grant 1500 / 3000 / 8
A Matilda doing its annual limit would spend 24 weeks in maintenance, a Crusader 20 weeks, a Valentine under 10 weeks, a Grant 16 weeks, a Stuart, the Honey, under 4 weeks. Investing in basic engineering for cost of building, reliability and ease of maintenance before building the new designs. Man hours per gun and carriage
2 pounder 2,682
6 pounder 1,293
17 pounder 2,726
25 pounder 3,085

A really good dual purpose HE/AP gun is very difficult in WWII as the higher the velocity the better the AP the worse the HE do scoping studies, including engine designs in the order of 500HP for tanks able to carry guns around 75mm to give HE performance and then what can be done for AP, while also updating bridging standards and ordering recovery vehicles. While doing that use the chassis as the basis for self propelled artillery.

Air force, better navigation training and more radio aids, a GEE system provides a faster fix than direction finding, simple inertial navigation improves over water navigation. You want coastal aircraft to be sure of where they are 200 miles out for a start, given early U-boat activities. The on board radars were noted as being very useful when returning, identifying the coast.

The two biggest areas of direct British losses 1939 to 1942 are the bombings of cities by night and the ships lost at sea. An important part in defence would be radar, to have the numbers required in 1940 means starting work around 2 to 3 years earlier, in theory starting slowly from 1925/26 building on the pulse echo idea for ionosphere research. Chain home to look outwards, then the next generation which track over land helping to eliminate the plotting errors associated with Observer Corps position reports. Radars for all medium and long range anti submarine aircraft and night fighters.

Force size, Bomber Command 1939 to 42 had the least return on investment, transferring 4 group to Coastal Command and put the Whitley VII into production instead of the V at the end of 1940 expanding Coastal Command ahead of Bomber Command. Transferring 2 Group to Fighter Command as the basis of the night fighter force and still form the historical night fighter units. To provide an adequate night fighter requires ordering the Beaufighter instead of the Beaufort, the fighter coming with racks for underwing bombs or fuel tanks and under fuselage bombs, fuel tank, mine or torpedo, in reality 254 Beauforts and Beaufighters to end June 1940, in the what if becoming around 130 Beaufighters in front line service, 40 to Coastal Command, the rest distributed amongst the night fighter units, 1 flight of Beaufighters mostly for combat, 2 of Blenheims mostly for training. By end 1940 there were 497 Beauforts and Beaufighters built.

Development of the Hercules needs to be speeded up, and can be helped by cancelling the Taurus, otherwise there is little disturbance of the actual aircraft production program with inevitable knock on effects from the above changes. Everyone knows the designs best not built if you want to use full hindsight and so on, Mosquito given the go ahead in 1938, the night fighter version appears in early 1941. It is so easy to know what to do after knowing the answer. Like build the Mosquito and outsource twin engine light/medium bomber design to the US, along with transports. The RAF urgently needed a twin engine bomber better than the Blenheim, yet after mid 1940 many of the losses cam for operations the RAF chose to do, not needed to do, the losses on operation channel stop for example and the way the Hurricane fighter bomber could replace them there.

The next level of combined arms is Army/Air Force joint planning. It is instructive to note the USAAC debates about the role in airpower in the 1920's by people like Spaatz and Arnold, they were about the next big war but often were reduced to ideas about 2 to 3 aircraft, the numbers they actually had available then. Who had control was a big one but also how many aircraft to the soldier, of what type, where used and so on. And what to build in peace time that would give them knowledge of what to build in war time, while still being useful in both peace and war time. While noting aviation was advancing far faster than any other military area, by the time something arrived in numbers someone else had a better one at least on the way. Procurement flops tend to result in cut budgets.

Ultimately it went something like this, the smallest type that could carry 2 to 3 people plus a radio and enough fuel for 2 or so hours, under control of the local army commander. a squadron or so per corps, operating mostly over friendly territory, venturing out to around artillery range, with a side line of leading the way if the ground unit was on the move. Every other aircraft under the air force subject to joint planning. Specialist multi crew bombers, normally conducting pre planned operations, if you like using yesterdays news, to hit the standard targets around the battlefield, needing escorts to do so safely. Ideally small/fast and/or dive and so able to operate at lower altitudes than the heavy bombers for greater accuracy. The problems of and times for getting an escorted bomber force over a target meant they could rarely be used for fleeting targets, reserving them for such duty turned out to be a significant waste. The final category is when the front is mobile or being able to hit targets of opportunity. The domain of the fighter bomber, they can defend themselves or come from the same unit, some as bomber, some as fighters, quicker to launch but more importantly able to orbit waiting for instructions and if no strike is requested then released to hunt targets of opportunity. We know that, it seems so logical and obvious. Pre war the army wanted air umbrellas, continual protection along with strike support. In France in 1944 at least they received it, but the size of the air force required was by pre war standards massive and needed a whole extra offensive force that pushed the enemy air force back from the battlefield allowing lots of small, heavily laden formations to operate low and slow with acceptable casualties.

May and June 1940 cost the Luftwaffe 28% of its starting strength, including 23% of its close range reconnaissance units, plenty of contested airspace. From the extensive lists at Martin's Aviation Pages 10 May to 22 June 1940, RAF France, 45 Battle abandoned, 136 lost, 21 Blenheim abandoned, 54 lost, 94 Hurricane abandoned, 161 lost, 37 Lysander lost, out of (abandoned + lost), 185 Battle, 204 Blenheim bomber, 21 Blenheim fighter, 403 Hurricane, 51 Lysander, 78 Spitfire fighters. Overall losses, 227 abandoned, 876 lost, 1,058 damaged, combat plus accidents. Not sure the Lysander did that badly given the circumstances, losses by squadron, 2 squadron - 4 aircraft, 4 squadron - 11 aircraft, 13 squadron - 9 aircraft, 16 squadron - 8 aircraft, 26 squadron - 14 aircraft.

Gloster built 194 Gauntlet in 1936, 10 Gauntlet and 278 Gladiator in 1937, 132 Gladiator and 10 Henley in 1938, 320 Gladiator, 171 Henley and 32 Hurricane in 1939, 16 Gladiator, 19 Henley and 1,211 Hurricane in 1940 (207 Gladiators were for export)

Squadrons of Bomber Command January 1938 by group,
1 Group, 15 (Hind), 18 (Hind), 21 (Hind), 34 (Hind), 40 (Hind), 57 (Hind), 62 (Hind), 82 (Hind), 88 (Battle), 90 (Blenheim I), 101 (Overstrand), 103 (Hind), 105 (Battle), 107 (Hind), 108 (Hind), 113 (Hind), 218 (Battle, Hart), 226 (Battle)

2 Group, 12 (Hind), 35 (Wellesley), 49 (Hind), 52 (Battle), 63 (Battle), 83 (Hind), 98 (Hind), 104 (Hind), 114 (Blenheim I), 139 (Blenheim I), 142 (Hind), 207 (Wellesley)

3 Group, 9 (Heyford III), 37 (Harrow), 38 (Hendon II), 77 (Wellesley), 99 (Heyford II,III), 102 (Heyford III), 115 (Harrow), 148 (Wellesley), 149 (Heyford I,II), 214 (Harrow)

4 Group, 7 (Heyford II, III), 10 (Whitley I), 51 (Anson I, Virginia X), 58 (Whitley I, II), 75 (Harrow), 76 (Wellesley), 78 (Whitley I, Heyford III), 97 (Heyford II), 166 (Heyford III), 215 (Harrow)

5 Group, 44 (Blenheim I), 50 (Hind), 61 (Anson I, Blenheim I), 110 (Blenheim I), 113 (Hind), 144 (Blenheim I), 211 (Hind)

Blenheim I, 8,839 pounds tare, 265 mph at 15,000 feet, 678 miles/230 mph/15,000 feet/1,000 pounds bombs, take off weight 13,100 pounds
Blenheim IV, 9,790 pounds tare, 266 mph at 11,800 feet, 1,160 miles/225 mph/15,000 feet/1,000 pounds bombs, take off weight 15,682 pounds
Battle I, 7,686 pounds tare, 241 mph at 15,000 feet, 795 miles/204 mph/15,000 feet/1,000 pounds bombs, take off weight 11,211 pounds
Lysander I, 4,768 pounds tare, 224 mph at 10,000 feet, 405 miles/192 mph/10,000 feet/no bombs, take off weight 6,282 pounds

Spitfire I at 180-190 mph, 8.9 mpg, adding 40 gallons gives a range of 930 miles, at 305 mpg, 6.4 mpg, 40 more gallons range 720 miles.

A 4 Pegasus engine bomber was called the Sunderland. Centaurus production began in October 1942.

Heavy bombers are the most economical way to deliver bombs, something that translates to lower running costs in peace time. RAF expansion plan A from July 1934, 8 Heavy, 8 medium, 25 light bomber squadrons, plan M from November 1938, 85 heavy bomber squadrons.

The British Army was a nominal 29 divisions in Britain and 3 in the Middle East in September 1939, 5 divisions in France by end 1939, 13 by end April 1940, many simply as work force, infantry without supporting arms.

Contract prices, British tanks, showing the savings due to mass production.
Matilda £18,000
Crusader £13,700
Valentine £14,900
Churchill £11,150
Cromwell £10,000

In August 1941 the US War Department let a $100-million order for 880 medium tanks, 2,300 light tanks and 1,090 armoured scout cars. In November Chrysler was awarded $127 million to expand their facilities and produce medium tanks. General Motors was awarded $25,780,000 to build the Flint Arsenal and Ford was awarded $39-million for the building the Grand Blanc Arsenal.

In September 1942 the 8th Report of the Army Service Forces Army Supply Plan, including the then current estimated costs, on "important" items of equipment. US prices are for the tank without armament and usually without the various items that were added as stowed equipment prior to unit issue.
Tank, Light, M3, M3A1, M5, M5A1 - $50,000
Tank Medium, M3 and M4 - $82,723
Tank, Heavy (undesignated) - $152,346

Gun, Tank, 37mm M5 and M6 - $1,425
Gun, Tank, 57mm - $5,500
Gun, Tank, 75mm M2 and M3 - $3,350
Gun, Tank, 76mm M1 - $3,500
Gun, Tank, 3" Heavy - $8,600

To compare the gun prices to the guns with carriage for use as antitank guns:
37mm - $3,480
57mm - $9,420
76mm - $21,300

Others are:
Gun, 40mm AA, mobile - $17,830
Gun, 3" AA, mobile - $37,500
Gun, 90mm AA, mobile - $43,800
Gun, 90mm AA, fixed Anti-MTB Mount - $23,000
Gun, 4.7" (120mm) AA, mobile - $151,000

Machine gun cost estimates were:
MG, calibre .30, M191A4 (fixed and flexible) - $350
MG, calibre .50, M2 HB (fixed and flexible) - $1,050

A summary of equipment costs dated 29 April 1944 gives the following representative costs:
Tank, Light, M5 and M5A1 - $37,560
Tank, Medium, M4 - $58,197
Tank, Heavy (undesignated) - $325,368
The "Tank, Heavy" was the M1, later re-designated as the M6. Only 40 were completed.

Aircraft Cannon, 75mm - $4,500
Gun, 40mm AA, with carriage - $13,100
Machine gun, calibre .30 - $147
Machine gun, calibre .50 - $323

Unit prices given for VJ-Day 1945 in a 1951 Army summary of costs were:
Tank, Medium, M4A3 - $47,339
Tank, Medium, M4A1 - $55,145
Tank, Light, M24 - $39,652
Tank, Medium M26 - $81,324

tomo pauk said:

Using a steel penetrator in the APCR Mk1 shot on the 2pdr gun means that penetrator is perhaps 25mm of diameter,

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I was referring to Mr William's proposed MK I shot for his 57mm gun.
Using a steel penetrator APCR shot for the historic 2pdr gun is not going to work well as the impact velocities are well into the shatter range.
The French 37mm APCR shot worked because the steel alloy penetrator would still work (not shatter) at the velocities the French 37mm guns were achieving.

tomo pauk said:

HE_capabilty multiplied with AP_capability = how good is a tank gun.
Army can make a decision to go with more substantial gun well before 1938, and that does not have to be the low MV 6pdr from ww1.

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The problem/s with a more substantial gun are that you need a more substantial tank to put it in.
And you are going to carry less ammo unless the tank is increased in size not just for the gun but for ammo storage.

The British really needed a new tank in 1942.
What they needed in 1940-41 was a lot less even though better than historic.

A large part of what they needed was better ammo. They needed better ammo for
Tank guns
AT guns.
25pdr field guns (better HE)
3in mortars (longer range)
larger artillery needed better shells (thinner walls/more HE)
Better bombs (more HE)

The Army needed better/more modern Artillery in general but the money had gone to the RAF.

tomo pauk said:

What kind of engine do you suggest for the Blenheim in 1936,

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Peregrines

tomo pauk said:

Depends what one wants. A 400 mph A/C? 350 mph? 320 mph max, like what the historical Beaufighters did most of the time? Ability to mix with Axis best, or that is not a requirement?
And what that aircraft is supposed to do - intercept enemy bombers (day or night or both), at how log a range, does it need to lug some bombs/rockets/torpedo? Sacrifice performance in order to get a lot of them, or make a small numner but with high performance? How good is the company when it is about really fast aircraft in the last, say, 10 years?

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A lot of the Hercules single engine aircraft depend on when.
There were two (?) single engine fighter proposals in 1935/36 that used Hercules engines of around 1500hp. Unfortunately a 1500hp Hercules was a little late in appearing.
Another problem was that Bristol (and most of the world up until 1941/42) thought that exhaust thrust from radials was not worth the effort.
There was a proposed 1940 (?) Bolton Paul light bomber/attack plane (P.35) that looked like it was designed by a team that had failed camel design. Hercules or Griffon power.
Included 2 Hispanos and eight .303s in the wing, a single 250lb bomb in each wing, not under. A single 250lb inside the fuselage bay (perhaps there was more than one fuselage bay?)
Tricycle landing gear with the rear legs folding forward leaving a little bit of wheel exposed, steeply swept outer wing to help with balloon cables, more but you get the idea.

Other companies just suggested updated Henley or P.4/34 (Fulmar) or land Barracuda.

By 1937/38 the single engine fighter proposals had shifted over the Vulture and Sabre.

It seems that the designers, for what ever reason, were not taken with the idea of the Hercules engine. Too much drag or uncertain future in the late 30s? The Sleeve valve was still somewhat experimental in the late 30s.

Mr. Sinclair has given us a very informative post with a lot of good information in it.

Geoffrey Sinclair said:

Man hours per gun and carriage
2 pounder 2,682
6 pounder 1,293
17 pounder 2,726
25 pounder 3,085

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This does show that the British were paying way, way too much for the 360 degree traverse on the 2pdr gun. A simple split trail with about 60 degrees of traverse would have cut the cost/man hours by at least half. Either more guns or more money for other things. Easier production might have allowed faster production after Dunkirk allowing for the change over to the 6pdr earlier.

Geoffrey Sinclair said:

. Understand the British Army in general had to reach a higher level of command for equivalent firepower compared to other armies, Bren versus MG42, 2 and 3 inch mortars versus 81mm, 25 pounder versus 105mm.

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The Bren was a lot closer in fire power to the MG 42 than many people think. The problem was not so much the rate of fire, it was the available ammo and the supply of spare barrels.
For the British the Vickers guns while not part of the official table of equipment many battalions had an attached Vickers gun platoon for extended durations.

Mortars changed during the war, on both sides. Germans started with a lot of 50mm mortars and the 81s were at battalion level. British 3in mortars were problem, France they only had 2 tubes per battalion. After France they went to 6 tubes. Unfortunately the 3in mortar had a rather short range which also increased reliance on higher command (actual artillery). In 1942 they beefed up the barrel and base plate to handle stronger charges and range went up to within a few hundred yds/meters of the German 81mm mortars.
The British 3in was actually 81mm and could fire captured German/Italian 81mm ammo. Setting the sights for the different ammo took some experience.
The British and German artillery organization was a bit different. On paper it looked very much the same but the Germans often split up the paper organizations into battle groups.
A battle group might get it's own battery of 105mm howitzers attached so that the group commander didn't have to send artillery fire requests to division HQ or filter through the division artillery HQ.
British Divisions tended to keep the artillery more centralized (not loan out battalions)

Something to remember here is that in a 5-6 year war a lot of things changed. In France in early 1940 a British infantry division might have 40 radios including the artillery. In Holland in late 1944 the division had almost 1000 radios. In late 1944 the British artillery system of fire (not the guns and ammo) was the best in the world. ANY forward observer had the authority and the responsibility to call for every gun within range and get shells on target in 5 minutes.

The whole 25pdr vs 105mm is worthy of a thread of it's own

Geoffrey Sinclair said:

A really good dual purpose HE/AP gun is very difficult in WWII as the higher the velocity the better the AP the worse the HE do scoping studies, including engine designs in the order of 500HP for tanks able to carry guns around 75mm to give HE performance and then what can be done for AP, while also updating bridging standards and ordering recovery vehicles. While doing that use the chassis as the basis for self propelled artillery.

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It was easy to do the really good dual purpose HE/AP gun in ww2. That was the case with many German guns, where the AP shots of different generations were using full charge, while the HE shells were using reduced charge.

Shortround6 said:

Using a steel penetrator APCR shot for the historic 2pdr gun is not going to work well as the impact velocities are well into the shatter range.
The French 37mm APCR shot worked because the steel alloy penetrator would still work (not shatter) at the velocities the French 37mm guns were achieving.

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The steel-cored APCRs can be used beyond 500m, while the 'normal' AP shots can be used on the closer ranges.

Shortround6 said:

The problem/s with a more substantial gun are that you need a more substantial tank to put it in.
And you are going to carry less ammo unless the tank is increased in size not just for the gun but for ammo storage.

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British tanks were alsredy more substantial that most of the French or German tanks. So put that ... substance into a good use.
Everyone was more than willing to pay the price of the lower ammo count when going from small guns to the bigger guns on the same tanks, so no worry there.

Shortround6 said:

The British really needed a new tank in 1942.
What they needed in 1940-41 was a lot less even though better than historic.

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I don't suggest a new tank vs. what they had in 1940-41, just that that tank is better armed and less cluttered (does not apply for the Matlida and Valentine).

Shortround6 said:

A large part of what they needed was better ammo. They needed better ammo for
Tank guns
AT guns.
25pdr field guns (better HE)
3in mortars (longer range)
larger artillery needed better shells (thinner walls/more HE)
Better bombs (more HE)

The Army needed better/more modern Artillery in general but the money had gone to the RAF.

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Agreed.

tomo pauk said:

It was easy to do the really good dual purpose HE/AP gun in ww2. That was the case with many German guns, where the AP shots of different generations were using full charge, while the HE shells were using reduced charge.

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Doctrine and sights. Germans put different aiming marks/scales in the sights and trained gunners to adjust the sight or sight picture for the different types of ammo. The British and Americans wanted all the shells to hit using the same aiming mark (or close) to simplify both training and sight construction (probably an error).

tomo pauk said:

The steel-cored APCRs can be used beyond 500m, while the 'normal' AP shots can be used on the closer ranges.

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Problem is that APCR ammo slows down faster and while it might work at 500m the small stuff gets a lot iffier at 1000m.
German 37mm AP 40 starts out great (30-50% depending on angle) at 100-200 meters but by 400 it is down to 14-29% depending on angle.
The German 5cm Pak 38 as the cross over starting at about 1250yds. Now please note that both of the these use Tungsten Carbide penetrators and are concentrating force into a smaller area.

tomo pauk said:

British tanks were alsredy more substantial that most of the French or German tanks. So put that ... substance into a good use.

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They did, they used the space for crew. We are talking volume, not weight. A Cromwell went into battle with with 64 rounds, a Churchill cold carry 84 rounds. The Sherman held 97 rounds. A 75mm Valentine carried 53 rounds and about 1/3 of the machine gun ammo of the Cromwell. 75mm Valentine also had a 2 man turret.
Crusader went from 110 rounds down to 65. Also went down to a two man turret for slower rate of fire and poorer situational awareness.
The Germans had the best crew layout and vision of the time in the MK III & IV tanks (still needed improvement).
Then they backtracked with the Covenanter and the Crusader and the............... didn't back in the vision game until the Comet.

tomo pauk said:

Everyone was more than willing to pay the price of the lower ammo count when going from small guns to the bigger guns on the same tanks, so no worry there.

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See above. The Sherman went from the 97 rounds of 75 to 71 rounds of 76mm to 42 rounds of 17pdr. And even then they lost the bow gunner (not anywhere near as bad as loosing turret crewman). The problem comes in when you are not fighting enemy armor but dug in infantry and towed AT guns. The tanks with small ammo capacities have to pull back out of action to rearm leaving their infantry supported by fewer tanks as they take turns.
They went to the bigger guns but there was definitely worry. Centurion I carried 70 rounds of 17pdr ammo.
US M-36 tank destroyer carried 47 rounds of 90mm and 1000 rounds of .50 cal, no small machine gun.
US M-26 tank carried 70 rounds of 90mm, 5,000 rounds of .30 cal and 550 rounds of .50 cal.

German MK III tank started with 121-131 rounds of 37mm and 4500 rounds of 7.9mm they ended with 54-64 rounds of short 75mm and 3750 rounds of 7.9mm
The short 75mm was on it's 3rd generation of HEAT shells while it did well for penetration, hitting ranges much past 500 meters started to become a problem.

The 2pdr was not a wonder weapon, but it was let down by the poor (one round only?) ammo selection issued by the British army for far too long.
Give it better projectiles (APCBC) and it wouldn't need trick APCR shells fired out of old WW I guns. Give it the same HE shells that everybody else was firing out their 37mm guns and while complaints about lack of HE wouldn't stop but they would be a lot less. At least Crusader crews wouldn't have to try firing 2in HE mortar rounds out of their 2in smoke mortars at close range for HE support.

Not sure if the British thought their crews couldn't deal with 2 different types of ammo and would get confused or what was going on.

Shortround6 said:

See above. The Sherman went from the 97 rounds of 75 to 71 rounds of 76mm to 42 rounds of 17pdr. And even then they lost the bow gunner (not anywhere near as bad as loosing turret crewman). The problem comes in when you are not fighting enemy armor but dug in infantry and towed AT guns. The tanks with small ammo capacities have to pull back out of action to rearm leaving their infantry supported by fewer tanks as they take turns.

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When you fight dug in infantry and towed AT guns, one 75-76mm shell has effect of perhaps 2-3 57-50 mm shells, or 5-6 37-40 mm shells.

Howard Gibson said:

It is too bad the British lacked an airframe suitable for the Centaurus. I have just read By Jupiter, by Bill Gunston. Roy Fedden had plans to manufacture Centauruses in Montreal Canada in 1940. Unfortunately, there was no immediate demand. They would have made good substitutes for the R3350s that were burning up B-29s.

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The Warwick was standing by to use Centaurus/Vulture/Sabre size/power engines with the Wellington thought of as the interim airframe until the Warwick got its two big engines. Vickers could easily transfer Wellington production into Warwick production. The build system being identical and drawing upon the same skills and materials for either.

I think we have to look at the progress of the Centaurus design as the drag here. Plus the urgency of Hercules production. We popularly note RollsRoyce's dropping of assorted other engines to maximise Merlin production and development but Bristol too dropped Perseus and Taurus development to concentrate upon the Hercules once both of the others had been made adequately reliable. With our clear hindsight we tend to look out the important through that hindsight but, at the time, urgency trumped important.

yulzari said:

The Warwick was standing by to use Centaurus/Vulture/Sabre size/power engines with the Wellington thought of as the interim airframe until the Warwick got its two big engines. Vickers could easily transfer Wellington production into Warwick production. The build system being identical and drawing upon the same skills and materials for either.

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The Warwick was tested with Centauruses in 1940, but the aircraft was not high priority.

Some options for the aero engines:
- Basic Merlin is as almost as good as it gets, and it should've provided even better 'mileage' if it is not wasted in many hundreds of irrelevant aircraft; having a surplus of Spitfires means that Hurricane does not need the heart transplant in 1940 thus leaving the Merlin XX for the Spitfire for BoB. No Exe, no Peregrine. RR can act even earlier with the 2-stage supercharging, that was known to work with V engines years before ww2.
- Bristol 850-1100 HP radials: I'd rather see the much improved superchargers on the Mercury and Pegasus than the resources invested in the Taurus; the earlier Hercules can be gotten into service, the better. Bristol was big in the inter-war altitude records with what were basically 2-stage supercharged engines, so there is a lot to be gained if these systems are adopted for the military use.
- As noted by the fellow member earlier, having Napier to make a big honking V12 instead of the Sabre would've been a boon. The Dagger might've been an useful (if a bit expensive) engine for the bombed-up fighters, for example something that Army might find interesting.
- Taking a look in the American radials, like the R-1830 or the R-2600, should've produced the actual engines more likely than it was the case with trying to mimic the G&R 14 at Alvis, or the 'dog' engines at A-S. Alvis + P&W, and A-S + Wright anyone?

Aircraft powered by these engines will do better if the engines have a much improved layout of exhausts, as well as with the more modern fuel metering systems - the float-type carbs were really a handbrake to the engine abilities.

What is clear today was not so clear in the late 30s.
Everybody knew that 100 octane fuel was coming, what was not understood/realized was vast improvement that 100/130 fuel could offer in some engines.
100 octane was really about 30% better than 87 octane if both are measured on the Performance Number scale and 100/130 is another 30% above 100 octane when running rich.
Air cooled engines did not benefit from 100/130 octane in the same way/extent that liquid cooled engines did. Air cooled engines were operating closer to the danger areas than the liquid cooled engines were and there was a lot of work needed on improving cooling.

Multi stage compressors were known going back to 1900 or late 1800s. The theory was known. But practice was not equaling theory. Even in industrial compressors. RR with Hooker really moved into the lead in compressor design. Not all companies could design comparable superchargers and many companies did not share information, even during the war.
Many companies did improve their superchargers during the war, but it was also race. For company A to equal company B's 1941 supercharger in 1942/3 did not mean they had really caught up unless company B had made no improvements in 1942/43. It could be that both companies had improved and company A was still behind.
Getting two stage superchargers to really work was very hard. That is to get them to work at different altitudes and at different loads. The RR two stage worked and worked well under a variety of conditions. P & W 2 stage superchargers used the neutral plus 2 speed drive to suit the air flow to the main supercharger at different altitudes.
The record setting Bristol 2 stage supercharger of the 30s was nice stunt but it was a stunt. They didn't even engage the 2nd stage until they were over 30,000ft. They were using an intercooler that never would have been acceptable on combat aircraft (too much drag at low altitude). It might point them in the right direction, it did not mean they had made it.

As far as Bristol goes. The older 9 cylinder engines had several problems. Lack of cooling was one, needing a stronger basic engine was another. Using more boost from a better supercharger wasn't going to do much unless they fixed the two basic problems. Bristol had also screwed themselves with their cylinder layout. They could adopt better exhaust systems for better thrust (not hard) but having the pipes have to do 180 degree turns right after leaving the cylinders was always going to result in less thrust that rearward facing exhaust pipes.

Most major engine companies thought they needed 3 different engines minimum. A small, a medium and a large. Bristol really screwed up because they tried to make 4 small engines and 1 medium. They were competing with themselves. And then they really screwed themselves with sleeve valve engines would not tolerate high boost pressure/BMEP. This problem did not show up until 100 and 100/130 fuel showed up and by that time Bristol was very deep in the hole. They can't use high boost pressures/BMEP without distorting or breaking the sleeves, they were close, maybe only 10-15% low but that was enough. Bristol got better but they were almost always behind Wright and P&W. Good superchargers on marginal engines does not work. Even if you could have stuck a Merlin XX supercharger on a Wright R-1820 engine in 1941 you were not going to get a 1200hp radial engine at 18,000ft.
The supercharger would do it. The existing cooling fins would not handle it and the crankcase/crankshaft would not handle it.

Shortround6 said:

Air cooled engines did not benefit from 100/130 octane in the same way/extent that liquid cooled engines did. Air cooled engines were operating closer to the danger areas than the liquid cooled engines were and there was a lot of work needed on improving cooling.

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Some engines - both liquid cooled and air cooled - benefitted more, some benefited less. The FS Mercury engines of late 1930s vintage went from being good for 800 HP at 9000 ft (and 840 HP at 14000 ft) on 87 oct fuel to 990 HP at 9000 ft on the early 100 oct fuel - an almost 25% increase.

Basically, only the Merlins were better in the % of extra power due to 100 oct fuel in that time, thatm in case of Mk.III gained about 35% at ~9000 ft (970 HP vs. 1300).

Shortround6 said:

The record setting Bristol 2 stage supercharger of the 30s was nice stunt but it was a stunt. They didn't even engage the 2nd stage until they were over 30,000ft. They were using an intercooler that never would have been acceptable on combat aircraft (too much drag at low altitude). It might point them in the right direction, it did not mean they had made it.

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Availability of the high-altitude models of engines does not mean that the low- or mid- altitude models are not made.
On the bombers, there is a lot of place to fit and streamline the intercoolers. So better start working on these, including the suitable gearing of both S/Cs, so the, at least, Welligtons and Hampdens can cruise well at 20000 ft instead at 15000 ft, with bomber Ensign-lookalike and Halifax (with Hercules) following suit.

Shortround6 said:

As far as Bristol goes. The older 9 cylinder engines had several problems. Lack of cooling was one, needing a stronger basic engine was another. Using more boost from a better supercharger wasn't going to do much unless they fixed the two basic problems. Bristol had also screwed themselves with their cylinder layout. They could adopt better exhaust systems for better thrust (not hard) but having the pipes have to do 180 degree turns right after leaving the cylinders was always going to result in less thrust that rearward facing exhaust pipes.

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As noted by the users of the Mercury and the 100 oct fuel, there was a lot of stretch wrt. the engine strength.
Appeal of the more refined superchargers is that they use less engine power to provide the same boost at the chosen altitude, meaning there is more power left to the prop (with IHP remaining the same).

Shortround6 said:

Most major engine companies thought they needed 3 different engines minimum. A small, a medium and a large. Bristol really screwed up because they tried to make 4 small engines and 1 medium. They were competing with themselves. And then they really screwed themselves with sleeve valve engines would not tolerate high boost pressure/BMEP. This problem did not show up until 100 and 100/130 fuel showed up and by that time Bristol was very deep in the hole. They can't use high boost pressures/BMEP without distorting or breaking the sleeves, they were close, maybe only 10-15% low but that was enough. Bristol got better but they were almost always behind Wright and P&W.

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Hence the suggestions to drop the Taurus in most of the what-if scenarios dealing with RAF for ww2.
High boost is not the only metric of the engine quality.

Shortround6 said:

Good superchargers on marginal engines does not work. Even if you could have stuck a Merlin XX supercharger on a Wright R-1820 engine in 1941 you were not going to get a 1200hp radial engine at 18,000ft.
The supercharger would do it. The existing cooling fins would not handle it and the crankcase/crankshaft would not handle it.

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Marginal engines don't achieve 25% power increase when going from 87 to the early 100 octane fuel.

This becames the same speke as the long range Spitfire - if it is not the 100% equivalent of the P-51D, then it is not worth it. To what I disagree 100% with.