British Rearmament Before World War 2

Why when 20 mm Hispano or Oerlikon are available if you have any money to spend?
Yes, the Vickers .50 was lower velocity than the Browning and besides 20mm had much more HE than any .50 on the planet. Even the US had concluded that .50 BMG was obsolescent as fighter/attack aircraft armament by 1943, it was only a combination of production momentum and US ordnance screwing up 20mm Hispano production that meant the Browning soldiered on for as long as it did.
 
showing the comparative mass of firepower in grams per second. the 50 cal arrangements are extremely competitive in this category. later in the video he presents evidence that you can often score dirty hits with a 50 cal armament where a 20mm gun will give you clean miss.
Is the 20mm not far better if you fit it with the LW style mineshells as it will do significant damage even if it hit none critical parts?
 
Even if it has a 60 round drum not a belt It's still better against a bomber than anything else available?
With rate of fire and the fact that you are carrying 4 hmg for the weight of two cannons you are probably firing 6 rounds from hmg for 2 for cannon.

Does a fighter carry its armament to win the air battle or to shoot down bombers.

I presume we are crossing a common historical doctrinal argument. I'd be in favour of win the air first (so the key question is what kills fighters better). In general with fighters being smaller its easier to get a kill so you get by with smaller ammunition.

The heavy machine gun is heavy enough to ignore the cheap bits of armour or self sealing fuel tanks that started to add to fighters mid way through 1940.

Anyway my point was that I can understand the historical decision to wait for cannons and I could understand someone going for heavy machine guns mid way through the 1930s.

Edit to add: Very rule of thumb. Comparing below the number of one weapon system against the other (2 cannons are similar weight to 4 hmg and similar weight to 8 lmg and the rounds fired by the other options for every 2 cannon rounds).

Number/rounds fired
LMG 8/16
HMG 4/6
Cannon 2 /2
 
Last edited:
With rate of fire and the fact that you are carrying 4 hmg for the weight of two cannons you are probably firing 6 rounds from hmg for 2 for cannon.

Does a fighter carry its armament to win the air battle or to shoot down bombers.

I presume we are crossing a common historical doctrinal argument. I'd be in favour of win the air first (so the key question is what kills fighters better). In general with fighters being smaller its easier to get a kill so you get by with smaller ammunition.

The heavy machine gun is heavy enough to ignore the cheap bits of armour or self sealing fuel tanks that started to add to fighters mid way through 1940.

Anyway my point was that I can understand the historical decision to wait for cannons and I could understand someone going for heavy machine guns mid way through the 1930s.

Edit to add: Very rule of thumb. Comparing below the number of one weapon system against the other (2 cannons are similar weight to 4 hmg and similar weight to 8 lmg and the rounds fired by the other options for every 2 cannon rounds).

Number/rounds fired
LMG 8/16
HMG 4/6
Cannon 2 /2

IMHO (no doubt somewhat with the benefit of hindsight..)

A reasonable path for the RAF might have been:
Plan A) Proceed with the .303 Browning more or less as they did in our time line (maybe carry out more pre war firing trials and if possible accelerate the development of modern AP, Incendiary and perhaps API style ammo.)

Plan B) Develop 20mm cannon systems (ie. drum and belt fed options along with modern API, and HE ammo (including "mine" style shells with as fast an ROF as possible.)

As a distant third choice look at a possible off the shelf buy (possibly followed by license production if needed) of .50 Browning's as a plan C if 20mm cannon systems are not ready in time and modern .303 ammo fired from 8 .303 Browning's isn't up to dealing with the threat aircraft. Ideally the RAF would jump from the .303 to the 20mm and skip over the HMG step.
 
There was still some doubt that a single naval seat fighter was doable as they saw there would be a need for a navigator to find the carrier again. The USN had worked out how to do this and had various radio and other navigational aids to help, the RN would need to agree that these were practicable and effective first before going for a navilised Sea Hurricane.
My answer is Sea Gladiator!

In the late '30s, a single seat land fighter WAS adopted in the FAA.

A modified Mk II, the Sea Gladiator, was developed for the Fleet Air Arm, with an arrestor hook, catapult attachment points, a strengthened airframe, and an underbelly fairing for a dinghy lifeboat, all for operations aboard aircraft carriers.[12][13] Of the 98 aircraft built as, or converted to, Sea Gladiators, 54 were still in service by the outbreak of the Second World War.[12]
 
Perhaps if the RN had gotten their twin 5.25" turret and remote power control system fully worked up well before WW2 and were able to produce it in quantity pre WW2 (which would likely be a POD on its own) that might have been another option for arming at least some 2,000 ton sloops. With director control, remote power control of the turrets and a reasonable rate of fire that might have been a potent weapon system for a convoy escort with both anti aircraft and anti surface capabilities. Depending on the time lines getting all that sorted out pre WW2 on a series of sloops might also have had some ripple effects vis a vis later battle ships and cruisers having better DP secondary armament as well. If there are issues accommodating the weight of the turrets in a 2,000 ton design maybe leave the bulk of the armor off the ship, but design the ship so it could be added later if the treaties are no longer in force ?
I think a 4.7"/45 standard DP wepons would have been better from 30s to end of WWII replacing all 4.7"/5.25/4.5" guns..... not that I think you will have spare expensive fire control for sloops, so old 2nd hand, hand worked 4" for them!
Yeah but the German navy seemed fixated on having 15 cm secondary guns on their larger ships so there may have been some perceived reasons why more or less 6" guns were seen as desirable by at least some navies in the WW2 era. Perhaps given the apparent German attitude to guns of that caliber (I seem to recall they even equipped some destroyers with them ?) equipping at least some RN escorts with similar caliber guns might have had a deterrent effect vis a vis German opponents ?

That being said I think the 5.25" might have been a better choice for the RN for a notional pre WW2 Sloop if they wanted something more powerful than their various 4.x " options (if only to help get the 5.25" system fully debugged for use on cruisers and battle ships.)
I think the 15cm idea (and the same RN 6" pre WWI) is more to stop a DDs charge with a relatively few hits at close range and very short time before they torpedo you?

I think It's far too expansive to fit 5.25s and anything not hand worked on a sloop? I would go for a couple of 4" single gun to be easy to work in an ocean seaway and sufficient to get through a sub pressure hull, anything more is wasted on a 2000t or less sloop that can't win a gunfight anyway?
 
Last edited:
I think a 4.7"/45 standard DP wepons would have been better from 30s to end of WWII replacing all 4.7"/5.25/4.5" guns..... not that I think you will have spare expensive fire control for sloops, so old 2nd hand, hand worked 4" for them!

I think the 15cm idea (and the same RN 6" pre WWI) is more to stop a DDs charge with a relatively few hits at close range and very short time before they torpedo you?

I think It's far too expansive to fit 5.25s and anything not hand worked on a sloop? I would go for a couple of 4" single gun to be easy to work in an ocean seaway and sufficient to get through a sub pressure hull, anything more is wasted on a 2000t or less sloop that can't win a gunfight anyway?

I am inclined to agree that the RN would have benefited from some rationalization vis a vis 4.5" thru 5.25" gun systems pre WW2. I do see a role for basic hand worked 4" systems no matter what.

The issue of equipping a 2,000 ton sloop style vessel with guns bigger than 4", using power turrets vs simple gun mounts and perhaps fitting complex fire control systems is likely going to at least partially hinge on the RN being able to build up a cruiser force that is fully compliant with the treaty and meets all their needs.

If the RN has already built all the cruisers they can and pre war feels they need more, then I could see them wanting to build sloops with at least some cruiser attributes (at least until the treaty is no longer relevant.)

Once war starts they might also see value in having slower vessels that don't need as much propulsion machinery as cruisers that can fill at least some of the role as a crusier (hence my suggestion to have a some what larger design prepared.)

The longer range of larger caliber and more powerful weapons might be of some value in the AA role and perhaps anti surface role in terms of engaging air craft and perhaps surface raiders as early as possible but yes I agree a complex fire control system would likely be needed to exploit the extra range and the RN might decide the extra cost wasn't with it.

Sorry I really don't have much to say re the realitive effects of various shell sizes on surface targets. I do believe larger / more powerful guns coupled with better fire control systems are probably more likely to score hits at longer ranges. Maybe a surface raider that comes under effective fire at longer ranges will be less likely to pursue merchant ships that escorts are protecting ? (Maybe the surface raider decides to sink the escort via long range gun fire as soon as the fire from the escort is perceived as effective by the raider, this in turn might give Merchant ships more time to escape ?) Maybe with hindsight larger caliber and longer ranged AA guns will be of more use against bombers equipped with early stand off weapons ?

Your comments re the perceived need to use 15cm guns to fend off torpedo attacks does make sense and I doubt that would be a major consideration for a sloop.
 
Last edited:
The issue of equipping a 2,000 ton sloop style vessel with guns bigger than 4", using power turrets vs simple gun mounts and perhaps fitting complex fire control systems is likely going to at least partially hinge on the RN being able to build up a cruiser force that is fully compliant with the treaty and meets all their needs.

If the RN has already built all the cruisers they can and pre war feels they need more, then can I could see them wanting to build sloops with at least some cruiser attributes (at least until the treaty is no longer relevant.)

Once war starts they might also see value in having slower vessels that don't need as much propulsion machinery as cruisers that can fill at least some of the role as a crusier (hence my suggestion to have a some what larger design prepared.)
I just dont think you ever get sufficient CLs for RN needs (or CV/BB guns) to start spending such limited resources/money on slow 2000t ships? Also Slow AA platform would want to get larger anyway for stability when shooting to make the most of good fire control, so large merchant (or old CLs) conversions not sloops?
Sorry I really don't have much to say re the realitive effects of various shell sizes on surface targets. I do believe larger / more powerful guns coupled with better fire control systems are probably more likely to score hits at longer ranges. Maybe a surface raider that comes under effective fire at longer ranges will be less likely to pursue merchant ships that escorts are protecting ? Maybe with hindsight larger caliber AA guns will be of more use against bombers equipped with early stand off weapons ?
I think you want 6" cruisers and 6" AA/DP (unlikely to get working by 45 without massive butterflies) at a minimum to hit stand-off aircraft?
 
I just dont think you ever get sufficient CLs for RN needs (or CV/BB guns) to start spending such limited resources/money on slow 2000t ships? Also Slow AA platform would want to get larger anyway for stability when shooting to make the most of good fire control, so large merchant (or old CLs) conversions not sloops?

I think you want 6" cruisers and 6" AA/DP (unlikely to get working by 45 without massive butterflies) at a minimum to hit stand-off aircraft?

You may very well be right on all counts :)

Altough maybe later without needing to worry about treaties the design might transform into something larger, more useful but with a speed well under 30 Knots. Building some 2,000 ton ships pre war might help iron out some of the details.
 
Last edited:
for a bunch of reasons. first off because that's a boring rehash of otl, and that's no fun.

also my mind works funny. i tend to focus on the unsexy details that don't show up on paper. note how that table never included the power of the ammo, only if it was available.
as long as a piece of kit can do the job it has been assigned then factors like cost, availability, and reliability are more important to me.



not necessarily, aiui the .50 cal guns worked just fine on any plane other than the 4 engine heavy bombers

here's a video on the p47 and it's armament. of note is a chart stating at 16:40 showing the comparative mass of firepower in grams per second. the 50 cal arrangements are extremely competitive in this category. later in the video he presents evidence that you can often score dirty hits with a 50 cal armament where a 20mm gun will give you clean miss.

but yeah for early war a .50 cal will do just fine
The problem with AN2 50 cal is it is almost 3 x heavier than a Mk 2 Browning .303 and the ammo is 5 x the weight

The .50 cal in a brace of 6 or 8 guns certainly makes sense but early war aircraft cannot mount such a weapon load out.

The 8 gun loadout on the P47 was over 600 KGs

A hurricanes armament was about 140 KGs all up - 8 guns plus 350 rounds per gun - a F4F-3 with 4 .50cal MGs (450 rounds per gun) all up is about 320 kgs - over twice as heavy.

So you can understand why the British went with Cannon as 4 x MK II HS404 20mm cannon were only 344 KGs - 2 cannon and 4 Browning 303s was 235 KGs while the 2 HS404 and 2 M2 .50 cal mounted in some Spitfires/Seafires was 276 KGs

Later in the war as engines got increasingly more powerful the ability to carry more 'dakka' increased

The USA did not go with cannon only because it struggled to reliably build 20mm cannon in a rare example of utter incompetence in the face of an obvious solution to the ongoing head spacing issue that was still dogging US made cannon long after the war was over.

I get it - they were late to the war they had not planned to fight in

It is perhaps fortunate that mid/late war the utter dominance of the allied air forces coupled with the relatively unarmoured Japanese aircraft and the largely single engine fighters making up the usual German opposition allowed the USAAF to muddle through with the .50 cal being good enough for most air targets.

A good early war weapon system IMO would be the FF series of cannon which was at 26.5 KGs lighter than the 29 kilo AN/M2 .50 cal and while its ROF and MV was inferior to the .50 cal it brought a relatively reliable explosive shell to the fight in time for 1940.

So my suggestion is to go the German / Japanese route with a 4 x FF 20mm cannon mounting on the Hurricane and a 2 x FF 20mm Cannon / 4 x MK2 Browning on the Spitfire (assuming the thin wing prevents an outer cannon being fitted.
 
I've been playing with this idea in my head about a standardized British DD design based on the I-class ships --- 1500 tons, 4 120mm guns, 8 to 10 torpedo tubes, 2x4 pom poms, 6 to 8 .50 caliber single AA MG (to be replaced with Polsen or Oeriklion 20mm in the future) welded hulls, unit machinery. Be willing to get a top speed of 34 knots instead of 36 knots. The ship will be a few feeet wider and perhaps a foot deeper in draft.

The big differences are the combination of hull welding and an extra ~130 long tons of displacement allows for a more comfortable ship that has a lot more endurance in all aspects (magazine, fuel, crew attention etc) plus having the mass and volume to take on upgrades.

Keep on building these ships in addition to TRIBALS. Make only major upgrades (4.5inch DP guns etc ) instead of minor ones to assembly line the production as much as possible.

I was thinking exact same types.....and a standardization based on those two types based on roles (as the roles are different).

I would SPAM out modified I-class (with y-turret removed and replaced with depth charges) for mid-ocean patrols....where their 4.7" (or 4.5") would not be effective against large enemy surface raiders. Against those surface raiders, priority would be on maximizing torpedo load so again agree on adding some displacement to ensure capability to carry 2x5 torpedo load.

Then SPAM out Tribals to be the primary Fleet Destroyer anywhere where their 4.7" (or 4.5") would be effective against enemy destroyers and torpedo boats.....with the caveat that any sane look at the Med or Asia would necessitate a re-worked AAA configuration.
 
Last edited:
Against those surface raiders, priority would be on maximizing torpedo load so again agree on adding some displacement to ensure capability to carry 2x5 torpedo load.
given the lack of success with far better IJN vessels, I don't think that is the right call
HMAS Yarra is illustrative of what an Erie type sloop would suffer against real warships attacking a convoy.
Other than no armor and 3 small 4" guns , slower and half the displacement, yeah, almost the same as an Erie.
And 3 CAs to a 1000 ton sloop, or 10,000 ton Exeter, there's only one outcome of that gang bang
 

Sooty

Banned
so, i'm looking at aircraft armaments, and some idea's i've come up with are:
ideapro'scon's
convert the Vickers .50 cal into an air cooled gun,everything important is already in production. trim down the mass and you have a decent hmg that you can mount in air craftpossibly obsolescent before development even begins
not sure if production can keep up with demand
convert the .50 Browning AN/M2 to .50 Vickerstakes advantage of current ammo production. raf is already switching to .303 browning's so the idea might gain acceptance
possibility to purchase additional units from us
requires new production lines for the guns.
might be better to just bight the bullet and use .50 bmg (that has it's own set of pros and cons)
develop an air craft variant of the 15 mm Besa machineguncan be (and was) used on the groundrequires new production lines for the guns and ammo
not sure if production can keep up with demand
heaviest option on this list
one more type of ammo to keep track of
use the F.N. Calibre 13,2 mm machinegunraf is already switching to .303 browning's so the idea might gain acceptance
possibility to purchase additional units from us
requires new production lines for the gun's and ammo
one more type of ammo to keep track of
50 Browning AN/M2 in .50 bmgraf is already switching to .303 browning's so the idea might gain acceptance
in full (if limited) production at start of war
ability to purchase additional units from us
requires new production lines for the gun's and ammo
one more type of ammo to keep track of
0.5" half the weight of a Browning M2.
 
I keep wondering how an M2 necked out to something larger ala the 16x99mm Vega would have performed as a substitute for a 20mm cannon early in the war? The shell should be large enough for a HE filling, considering that the 15mm MG151 had them.
 
given the lack of success with far better IJN vessels, I don't think that is the right call.

Just a hypothetical, you're the captain of the Admiral Scheer and you come across a convoy with your choice of 6 Tribals with 4 Torpedoes each and many 4.7" guns, or 6 TTL I-class with 10 Torpedoes each, which would you prefer to engage?

Don't forget, that German captain won't know about IJN success rates at that time.

He will be able to count the opposing Destroyers and multiply each by "10 torpedoes" each of which could give him a bad day and weigh the potential risk to his ship and his men.

If only facing 4.7" guns I think that captain would assess that risk to his ship and men at close to zero.
 
The main problem is that the J Types usually lost their after bank of tubes for a high angle 4inAA mount, whereas the Tribals traded one of their twin 4.7's for a HA 4in twin instead. It's pretty much a wash.

A better investment from hindsight would have been something like the late war 'Weapon' Class with their original layout of three twin 4in DP, 10 21in tubes and a 40mm light AA battery.
 
Top