Why no heavier RAF machine gun calibres? (1 Viewer)

[pbehn]

If the British had called their cannons 80 CAL and stopped fitting 0.303 MGs in Spitfires in 1940 regardless of the reasons they did it for, then this discussion wouldnt happen.

 

[SaparotRob]

Wasn't the problem getting the larger calibers to work which the .303s did?

 

[pbehn]

Wasn't the problem getting the larger calibers to work which the .303s did?

Of course, and both the gun and the munitions are heavier which adds to the problem. When the Whirlwind was ordered no single engine was powerful enough to lift 4 cannons in its wings and cannons didnt fire effectively or reliably in aircraft wings at the time. Stanford Tuck wanted cannon in 1940, but so did the RAF. If there was a cannon as reliable and long firing as a 0.303MG then it would have been fitted. As it was they didnt get cannons to work reliably until after the BoB and it has been discussed ever since.

 

[PAT303]

The .50 was better for that than the 20MM, ESPECIALLY after the API round came out. You throw out a hellava more rounds with .50's than 20MM, thus enabling more hits during those fleeting sight pictures of fighter vs. fighter combat.

The Hispano had a higher rate of fire than the .50 browning as well as having more effective ammunition, two 20mm's being the equivalent to six .50's so don't know where your coming from here, I bet if P47's-P51's pilots had four Hispano's fitted and loaded with SAPI HEI API belts they would never give the .50 and M8 rounds another thought.

 

[Alan Stevens]

Consider, if the Computer system worked against a target at a 400= MPH closing speed. then all of the B-29 losses would be from flak or mechanical failure. I know if I was behind the sight, I would use all the guns I had to protect my crew and save nothing.

I would not argue against bringing as may barrels into the fight as possible.

I just wondered if there was a selector switch on that forward upper turret.

 

[Reluctant Poster]

It was probably called only by the Americans as such.
The .303 Browning won the war, since it was instrumental in giving the Luftwaffe the 1st taste of defeat.


War was being won (or lost) in Europe and in North Atlantic. SBDs played almost no role there.

The war was won when the British Purchasing Commission gave $100,000,000 to Todd Shipbuilding to construct 60 Ocean Class freighters and to construct the entirely new yards where they were to be built. The Ocean Class freighter was designed by J L Thompson and Sons to be cheap to build and cheap to run. One of the myths is that the design they brought with them was based on an 1879 tramp steamer. This is complete nonsense. It was an up-to-date design with extensive water tank testing to develop a hull form with low resistance yet with as few curves as possible to make it easy to build and cheap to run.
At the same time as the Oceans were being built the Americans began producing their modified version of this design, the Liberty ship. The main change was the substitution of oil-fired water tube boilers for coal fired scotch boilers. Contrary to popular opinion when the Americans continued producing the design they did not redesign it for welding. The design was always intended to be riveted and or welded and in fact some British shipyards made extensive use of welding and only one American shipyard use full welding.

Without the 2,700 + Liberty ships and 100s of the same design produced in Canada and Britain bringing everything needed to fight a war across the oceans nothing else matters.

Honorable mention goes to Sun Ship Building's T-2 tanker design.

 

[PAT303]

The war was won when the British Purchasing Commission gave $100,000,000 to Todd Shipbuilding to construct 60 Ocean Class freighters and to construct the entirely new yards where they were to be built. The Ocean Class freighter was designed by J L Thompson and Sons to be cheap to build and cheap to run. One of the myths is that the design they brought with them was based on an 1879 tramp steamer. This is complete nonsense. It was an up-to-date design with extensive water tank testing to develop a hull form with low resistance yet with as few curves as possible to make it easy to build and cheap to run.
At the same time as the Oceans were being built the Americans began producing their modified version of this design, the Liberty ship. The main change was the substitution of oil-fired water tube boilers for coal fired scotch boilers. Contrary to popular opinion when the Americans continued producing the design they did not redesign it for welding. The design was always intended to be riveted and or welded and in fact some British shipyards made extensive use of welding and only one American shipyard use full welding.

Without the 2,700 + Liberty ships and 100s of the same design produced in Canada and Britain bringing everything needed to fight a war across the oceans nothing else matters.

Honorable mention goes to Sun Ship Building's T-2 tanker design.

I think your going to have to expand on this, I think we are all very interested in learning more.

 

[Thumpalumpacus]

I think your going to have to expand on this, I think we are all very interested in learning more.

There's that whole Battle of the Atlantic thing, you might have heard of it.

 

[z42]

There's that whole Battle of the Atlantic thing, you might have heard of it.

Here's a short overview in case someone missed it:
View: https://youtube.com/watch?v=dCqa9_ZOnT0&pp=ygUcbWl0c2kgYmF0dGxlIG9mIHRoZSBhdGxhbnRpYw%3D%3D

 

[PAT303]

There's that whole Battle of the Atlantic thing, you might have heard of it.

Referring to the money granted for the design and manufacturing of the ocean class of freighters

 

[EwenS]

I think your going to have to expand on this, I think we are all very interested in learning more.

John Henshaw in his book " Liberty's Provenance. The Evolution of the Liberty Ship from its Sunderland Origins" published in 2019 delves into the whole subject in detail and demolishing the various myths and claims that grew up from early on in the story of the Liberty Ship.

https://www.amazon.co.uk/gp/aw/d/B07R992LB8/ref=tmm_kin_swatch_0?ie=UTF8&dib_tag=se&dib=eyJ2IjoiMSJ9.FPOS_OS9NusCAGI1joG9o5fjTcbksOb-eO3DP1bNsCLMD394ZedFMVhefvwNU24SdjOcAp6KJQ7xT06vYawP8_ARGJ2C7Q-DzQUba-7O_Pl-8KQLAAPtE3hkzoB3A97qdhXYxvVr2JpEOzQ3DZuBkXIhAUVmVXJN0Oca11YG23lCVgZiNZbf3g3xxXBdUTMME8p7bsdxDnLKIvGqwY8cSw._EWbFkHclUmSgvb9AmhSioNAtpGO7TSg8ecB-lFxxn8&qid=1733993139&sr=8-9

Currently available heavily discounted here.

https://www.naval-military-press.com/product/libertys-provenancethe-evolution-of-the-liberty-ship-from-its-sunderland-origins/

The family tree can be traced back to Thompson's SS Embassage (completed Sept 1935), to SS Dorrington Court (completed May 1939), to the Empire Wind / Wave series (completed Oct 1940 to Oct 1941), to the Empire Liberty series (completed Nov 1941 to Oct 1944).

Thompson led a Mission to the USA in Sept 1940 to see about constructing new merchant ships there. (Confusingly there was another Mission at the same time concerned with acquiring existing ships from the US merchant fleet.). But he arrived in the middle of the US elections so initially it proved difficult getting officialdom engaged. In the space of 3 weeks he toured 35 shipyards in the US and Canada, plus engineering works and potential green field sites. Negotiations proved difficult. Many yards were already very busy with home orders. Many in the USA thought Britain a lost cause and didn't want to become involved.

Then Henry Kaiser appeared on the scene. The first meeting was on 23 Oct 1940. More meetings followed and a report went to the US Treasury Dept on 13 Nov. The deal was worth about £24m ($100m in 1940 terms) with 10% relating to the two new shipyards and the remainder for 60 ships. On 1 Dec he received the necesary US approvals and sailed for Britain on the 6th with all the necessary contracts, only to be sunk by a U-boat en route. Fortunately he and his soggy paperwork were rescued, and despite protests from the British Treasury that the cost was higher than expected, the contract was signed on 20 Dec 1940.

The ship plans Thompson took with him to the USA were those of the Empire Liberty according to the company history written in 1946. The US Naval architects Gibbs & Cox became involved in assisting the amendment of those plans to suit Kaiser's methods, including widespread use of welding, and assembly by a new largely unskilled workforce, which required many more drawings of greater accuracy than would have been normal for a British yard with a skilled workforce. And so was born the Ocean class.

The Richmond yard on the west coast was quickly constructed and was able to lay down its first Ocean on 14 April 1941. It was launched as Ocean Vanguard on 16 Aug 1941 and completed Nov 1941.

The Portland, Maine site proved a bit more difficult to construct, but managed to lay its first ship down on 24 May 1941.

At the beginning of Dec 1940, someone from Thompson's Mission went to Canada and signed contracts for the construction of the first Ocean type vessels there. These became the -

Fort ships - coal fired with 3 Scotch boilers (198 built)
Park ships - as above for the Canadian govt owned Park Steamship Co Ltd (114 built)
Victory ships - (not to be confused with the later US Victory ships) - two water tube oil fired boilers identical to the Liberty ships.
Canadian ships - 3 Scotch boilers but capable of burning coal or oil.

Meanwhile back in the US the US Maritime Commission (USMC) was trying to decide which US designed ships could / should be built. Three days before Thompson left for Britain there was a request from the White House to Gibbs & Cox for details of the Oceans, as the newly re-elected President wanted another increase in merchant shipbuilding. Thompson agreed to the release. On 26 Dec 1940 the head of the USMC, seeing the writing on the wall, wrote to the President proposing a new construction programme including 200 of a new emergency type. Eventually in Jan 1941 it was decided to base it on the Ocean but modified to meet US requirements. Gibbs & Cox were once again involved. The first Liberty Ship was laid down on 30 April 1941, just 6 weeks after contracts were signed, and about 3 months after the decision to base it on the Ocean design.

So what changes were made to get from an Ocean to a Liberty? Well firstly most of the framing forming the bones of the two types were identical. Thereafter:-

1. Oil firing in place of coal, with oil tanks in the double bottom and the coal bunkers eliminated in no3 hold.
2. Water tube boilers in place of Scotch type.
3. Combining accommodation amidships into one block.
4. Reduction in number of different plate thicknesses required in construction from 75 to 27.
5. Minimization or removal of deck camber where possible, again to simplify construction
6. A number of other more minor modifications to replace chain railings or canvas Dodgers with steel bulwarks, different davits for lifeboats.

So in summary a US Liberty was an amended Ocean design which in turn was an amended Empire Liberty designed by Thompsons in early / mid 1940. Gibbs & Cox were involved in both amendments, but their claim to have designed the Liberty Ship is without foundation, as the author John Henshaw demonstrates. Given the timescales it would have been impossible for them to design an entirely new ship from a blank sheet of paper.

 

[PAT303]

John Henshaw in his book " Liberty's Provenance. The Evolution of the Liberty Ship from its Sunderland Origins" published in 2019 delves into the whole subject in detail and demolishing the various myths and claims that grew up from early on in the story of the Liberty Ship.

https://www.amazon.co.uk/gp/aw/d/B07R992LB8/ref=tmm_kin_swatch_0?ie=UTF8&dib_tag=se&dib=eyJ2IjoiMSJ9.FPOS_OS9NusCAGI1joG9o5fjTcbksOb-eO3DP1bNsCLMD394ZedFMVhefvwNU24SdjOcAp6KJQ7xT06vYawP8_ARGJ2C7Q-DzQUba-7O_Pl-8KQLAAPtE3hkzoB3A97qdhXYxvVr2JpEOzQ3DZuBkXIhAUVmVXJN0Oca11YG23lCVgZiNZbf3g3xxXBdUTMME8p7bsdxDnLKIvGqwY8cSw._EWbFkHclUmSgvb9AmhSioNAtpGO7TSg8ecB-lFxxn8&qid=1733993139&sr=8-9

Currently available heavily discounted here.

https://www.naval-military-press.com/product/libertys-provenancethe-evolution-of-the-liberty-ship-from-its-sunderland-origins/

The family tree can be traced back to Thompson's SS Embassage (completed Sept 1935), to SS Dorrington Court (completed May 1939), to the Empire Wind / Wave series (completed Oct 1940 to Oct 1941), to the Empire Liberty series (completed Nov 1941 to Oct 1944).

Thompson led a Mission to the USA in Sept 1940 to see about constructing new merchant ships there. (Confusingly there was another Mission at the same time concerned with acquiring existing ships from the US merchant fleet.). But he arrived in the middle of the US elections so initially it proved difficult getting officialdom engaged. In the space of 3 weeks he toured 35 shipyards in the US and Canada, plus engineering works and potential green field sites. Negotiations proved difficult. Many yards were already very busy with home orders. Many in the USA thought Britain a lost cause and didn't want to become involved.

Then Henry Kaiser appeared on the scene. The first meeting was on 23 Oct 1940. More meetings followed and a report went to the US Treasury Dept on 13 Nov. The deal was worth about £24m ($100m in 1940 terms) with 10% relating to the two new shipyards and the remainder for 60 ships. On 1 Dec he received the necesary US approvals and sailed for Britain on the 6th with all the necessary contracts, only to be sunk by a U-boat en route. Fortunately he and his soggy paperwork were rescued, and despite protests from the British Treasury that the cost was higher than expected, the contract was signed on 20 Dec 1940.

The ship plans Thompson took with him to the USA were those of the Empire Liberty according to the company history written in 1946. The US Naval architects Gibbs & Cox became involved in assisting the amendment of those plans to suit Kaiser's methods, including widespread use of welding, and assembly by a new largely unskilled workforce, which required many more drawings of greater accuracy than would have been normal for a British yard with a skilled workforce. And so was born the Ocean class.

The Richmond yard on the west coast was quickly constructed and was able to lay down its first Ocean on 14 April 1941. It was launched as Ocean Vanguard on 16 Aug 1941 and completed Nov 1941.

The Portland, Maine site proved a bit more difficult to construct, but managed to lay its first ship down on 24 May 1941.

At the beginning of Dec 1940, someone from Thompson's Mission went to Canada and signed contracts for the construction of the first Ocean type vessels there. These became the -

Fort ships - coal fired with 3 Scotch boilers (198 built)
Park ships - as above for the Canadian govt owned Park Steamship Co Ltd (114 built)
Victory ships - (not to be confused with the later US Victory ships) - two water tube oil fired boilers identical to the Liberty ships.
Canadian ships - 3 Scotch boilers but capable of burning coal or oil.

Meanwhile back in the US the US Maritime Commission (USMC) was trying to decide which US designed ships could / should be built. Three days before Thompson left for Britain there was a request from the White House to Gibbs & Cox for details of the Oceans, as the newly re-elected President wanted another increase in merchant shipbuilding. Thompson agreed to the release. On 26 Dec 1940 the head of the USMC, seeing the writing on the wall, wrote to the President proposing a new construction programme including 200 of a new emergency type. Eventually in Jan 1941 it was decided to base it on the Ocean but modified to meet US requirements. Gibbs & Cox were once again involved. The first Liberty Ship was laid down on 30 April 1941, just 6 weeks after contracts were signed, and about 3 months after the decision to base it on the Ocean design.

So what changes were made to get from an Ocean to a Liberty? Well firstly most of the framing forming the bones of the two types were identical. Thereafter:-

1. Oil firing in place of coal, with oil tanks in the double bottom and the coal bunkers eliminated in no3 hold.
2. Water tube boilers in place of Scotch type.
3. Combining accommodation amidships into one block.
4. Reduction in number of different plate thicknesses required in construction from 75 to 27.
5. Minimization or removal of deck camber where possible, again to simplify construction
6. A number of other more minor modifications to replace chain railings or canvas Dodgers with steel bulwarks, different davits for lifeboats.

So in summary a US Liberty was an amended Ocean design which in turn was an amended Empire Liberty designed by Thompsons in early / mid 1940. Gibbs & Cox were involved in both amendments, but their claim to have designed the Liberty Ship is without foundation, as the author John Henshaw demonstrates. Given the timescales it would have been impossible for them to design an entirely new ship from a blank sheet of paper.

Brilliantly informative post as always Ewen, thanks mate.