Browning says demand for M2 is booming

[Interlinked]

13 hours ago, Rick said:

Regarding the Soviets, did fact that several U.S. 4 engine bombers, including some B29's, cause the choice for the heavy armament for the MIG 15?

The idea of a 37mm gun as fighter armament came shortly after Barbarossa, long before the problem of defending against heavy bombers became a real concern. There was a mid-war desire to give fighters "universal" gun armament, and when this was combined with a preference for a 3-gun combo of 2x lighter guns + 1 heavy gun, fighter gun armaments built up a final configuration of 2x 23mm + 37mm. The 37mm was developed during the mid-war period because it could give the desired "one hit kill" capability against tactical aircraft (not bombers) while also having good effects on ground targets. It was not conceived as an anti-bomber weapon.

Earlier configurations included 2x 12.7mm + engine 23mm, then 2x 20mm + engine 23mm, and then 2x 20mm + engine 37mm. During the creation of the Yak-9UT, it was recognized that 2x20mm + engine 23mm was better for air combat, while 2x20mm + engine 37mm was more flexible because of better effects on ground targets. This evolved into 2x 23mm + 37mm in postwar fighters and was carried over to jets.

[Stuart Galbraith]

22 hours ago, bojan said:

2, not 6.

Even with cannons removed there was no place for more than 4, hence Brits decided that 20mm was better choice if you can fit only limited number of guns.

TBH, you could have filled the thing full of .50's (if they fit and I accept you are right, they probably wouldnt) and it would have turned like a ruptured duck.   The .30 had apparently a weight of 31 lb. The .50 was listed at 84lb (I dont know if the aircraft installation was any lighter). So I dont see how that could work in what was a comparatively small aircraft compared to the P51 and the P47. It already had a relatively poor rate of roll at low altitude, hence why they clipped the wings.. The Germans also compartively lightly armed the 109 (and it paid for it when the luftwaffe insisted on bolting 30mm's on it).

There was presumably a similar dilemma for the Soviets. We sent Hurricane IIB's IIRC, which at least some had 12 gun wings (.303). The Soviets pulled all the guns and fitted them with 2 Soviet 20mm's and 2 12.7's. They could surely have fitted at least 6 12.7's, but  I guess they prefered the ability to turn(and add a miniscule amount of extra speed) than strict firepower.

To me, this all points to the problem being less the space, than the increased weight. I think a 20mm was a better choice than .50, except if you couldnt fit them.

The question to me the question is not 'why didnt they give the Spitfire 6 .50's, its 'why didnt the P51 get 20mm cannons.' After all P51A's built for the RAF got them, and  they seemed to work with the airframe ok, albeit on comparatively low altitude operations compared to the merlin powered ones operated by the USAAF.

Edited October 17, 2025 by Stuart Galbraith

[Stuart Galbraith]

1 hour ago, Markus Becker said:

That's what ended up happening but it wasn't planned at all. The so called Bomber Mafia was 110% convinced that bombers didn't need a fighter escort in the first place. Allegedly so much that they even stonewalled the introduction of long range version of the P-47 that could have been operational much sooner than the P-51.

I'm going that they continued to the .50 because that's all they had. They certainly wanted cannons but could not make them work. 

Well they had the one Hispano on the P38, and it kept jamming all the damn time. The USAAF seemingly  seemingly ignored RAF efforts on the Hispano, whom had similar troubles with its reliablity on integration on the Spitfire 1B during the Battle of Britain. In British service, the Hispano eventually worked fine. NIH applies I guess.

 

Edited October 17, 2025 by Stuart Galbraith

[Markus Becker]

6 hours ago, Interlinked said:

The idea of a 37mm gun as fighter armament came shortly after Barbarossa, long before the problem of defending against heavy bombers became a real concern. There was a mid-war desire to give fighters "universal" gun armament, and when this was combined with a preference for a 3-gun combo of 2x lighter guns + 1 heavy gun, fighter gun armaments built up a final configuration of 2x 23mm + 37mm. The 37mm was developed during the mid-war period because it could give the desired "one hit kill" capability against tactical aircraft (not bombers) while also having good effects on ground targets. It was not conceived as an anti-bomber weapon.

 

The P-39 and it's 37mm Browning cannon immediately come to my mind. 

[Markus Becker]

5 hours ago, Stuart Galbraith said:

Well they had the one Hispano on the P38, and it kept jamming all the damn time. The USAAF seemingly  seemingly ignored RAF efforts on the Hispano, whom had similar troubles with its reliablity on integration on the Spitfire 1B during the Battle of Britain. In British service, the Hispano eventually worked fine. NIH applies I guess.

Per Wikipedia that was easy to clear in flight with a manual re cocking mechanism. Probably just a lever and a connection rod. A system for wing mounted guns was developed but dropped by the RAF because their 20s didn't need it. 

The problems during the BoB were either teething troubles or related to switching from drum mags to belted ammo and short lived in any case. 

[Ssnake]

5 hours ago, Stuart Galbraith said:

To me, this all points to the problem being less the space, than the increased weight. I think a 20mm was a better choice than .50, except if you couldnt fit them.

It's not just volume and weight, but where you place your masses. For quick maneuverability you want the masses to be concentrated as closely to the aircraft's center of gravity as possible. A gun on a wingtip has the full length of the wing as leverage for increased rotational inertia.

[Stuart Galbraith]

1 hour ago, Markus Becker said:

Per Wikipedia that was easy to clear in flight with a manual re cocking mechanism. Probably just a lever and a connection rod. A system for wing mounted guns was developed but dropped by the RAF because their 20s didn't need it. 

The problems during the BoB were either teething troubles or related to switching from drum mags to belted ammo and short lived in any case. 

It was ammunition feed problems during turns apparently. When Martin Baker designed a new ammunition feed, the problem went away.

Interestingly it took years to shake off the legacy. Douglas Bader distrusted cannon armament so much he stuck with an all 303 Spitfire VA, whilst pretty much everyone  else was using cannon armed VBs. Mind you, he was a bit of a prick.

[Markus Becker]

52 minutes ago, Stuart Galbraith said:

Interestingly it took years to shake off the legacy. Douglas Bader distrusted cannon armament so much he stuck with an all 303 Spitfire VA, whilst pretty much everyone  else was using cannon armed VBs. Mind you, he was a bit of a prick.

First impressions matter: SB2C, P-39 and Ross Rifle, though that was 1st to 3rd or 4th. 

 

[R011]

9 hours ago, Stuart Galbraith said:

Well they had the one Hispano on the P38, and it kept jamming all the damn time. The USAAF seemingly  seemingly ignored RAF efforts on the Hispano, whom had similar troubles with its reliablity on integration on the Spitfire 1B during the Battle of Britain. In British service, the Hispano eventually worked fine. NIH applies I guess.

 

It was a manufacturing issue with US made guns themselves, not the mounting.  US made Lend Lease Hispanos stayed in storage rather than be fitted to RAF aircraft.

[Yama]

9 hours ago, Stuart Galbraith said:

Well they had the one Hispano on the P38, and it kept jamming all the damn time. The USAAF seemingly  seemingly ignored RAF efforts on the Hispano, whom had similar troubles with its reliablity on integration on the Spitfire 1B during the Battle of Britain. In British service, the Hispano eventually worked fine. NIH applies I guess.

A gun expert once described Hispano-Suiza as a "watchmaker company who never made guns suited for wartime use", and said that 20mm HS only became serviceable after years of engineering by Brits and Americans. Finnish experience on 20mm Hispano on Morane-Saulnier was fairly negative, and most of the MS 406 actually had a machinegun as centreline weapon.

1960s acquisition of 30mm Hispano-Suiza did not improve perception on the manufacturer...

 

[sunday]

1 hour ago, Yama said:

Hispano-Suiza as a "watchmaker company

Yeah, sure.

https://en.wikipedia.org/wiki/Hispano-Suiza_piston_aero-engines

[Ssnake]

1 hour ago, Yama said:

A gun expert once described Hispano-Suiza as a "watchmaker company who never made guns suited for wartime use",

Sadly, that didn't stop them from dabbling with armored fighting vehicles.

[Yama]

46 minutes ago, sunday said:

Yeah, sure.

https://en.wikipedia.org/wiki/Hispano-Suiza_piston_aero-engines

He probably wasn't too familiar with their other exploits, only referred their gun division...

[bojan]

5 hours ago, Markus Becker said:

First impressions matter: SB2C, P-39 and Ross Rifle, though that was 1st to 3rd or 4th. 

Unlike SB2C and Ross, there was nothing fundamentally wrong with P-39.

[Stuart Galbraith]

10 hours ago, Yama said:

A gun expert once described Hispano-Suiza as a "watchmaker company who never made guns suited for wartime use", and said that 20mm HS only became serviceable after years of engineering by Brits and Americans. Finnish experience on 20mm Hispano on Morane-Saulnier was fairly negative, and most of the MS 406 actually had a machinegun as centreline weapon.

1960s acquisition of 30mm Hispano-Suiza did not improve perception on the manufacturer...

 

Well, I think they were reliably working in British service by 1941, so I think 'years' was an exaggeration on their part. 

11 hours ago, R011 said:

It was a manufacturing issue with US made guns themselves, not the mounting.  US made Lend Lease Hispanos stayed in storage rather than be fitted to RAF aircraft.

I dont doubt you are right, but to me that is even more incomprehensible. They listen to the RAF about putting Merlins in Mustang. They listen to the RAF about building lighter airframes. They listen to the RAF about Radar, but for some reason, it completely seems to miss their attention the RAF have cannons, and they have been working reliably for years.

 

[Stuart Galbraith]

9 hours ago, sunday said:

Yeah, sure.

https://en.wikipedia.org/wiki/Hispano-Suiza_piston_aero-engines

It also seems to be forgotten quite how many of them powered Schneider Tropy aircraft.

https://en.wikipedia.org/wiki/List_of_Schneider_Trophy_aircraft

[Stuart Galbraith]

7 hours ago, bojan said:

Unlike SB2C and Ross, there was nothing fundamentally wrong with P-39.

No, it was just built for the wrong war.

In the European theatre, combat wasnt occuring where the P39 was at its best, on the deck. On the Eastern Front combat seemingly rarely occurred about 10000 feet. Add in US radios, and the 37mm, yes, Im not surprised they liked it. That said, I think they stripped out the under wing guns to improve its manoeuvrablity.

[Yama]

1 hour ago, Stuart Galbraith said:

Well, I think they were reliably working in British service by 1941, so I think 'years' was an exaggeration on their part. 

I dont doubt you are right, but to me that is even more incomprehensible. 

Well, Americans also fluffed up copying MG151...

[Stuart Galbraith]

38 minutes ago, Yama said:

Well, Americans also fluffed up copying MG151...

'Look what you could have won!'

https://en.wikipedia.org/wiki/ADEN_cannon

[Markus Becker]

10 hours ago, bojan said:

Unlike SB2C and Ross, there was nothing fundamentally wrong with P-39.

None of them was fundamentally flawed.

The Ross was IMO the worst of them but it was debugged in the end. But only after everyone had completely lost faith in it, so it was replaced anyway.

The SB2C had its specs changed when already in development and was rushed. Thus the -1 and -2 were utter garbage, the -3 was a lot less bad and even saw a bit of combat. The -4 and -5 were reliable, very capable and well liked.

The early P-39s had some mechanical issues and an engine with a critical altitude that would have been ok-ish in 1940. Max speed was reached at just 12k feet and dropped very fast at higher altitude. The models the Soviets got were good up to 20k feet.

[R011]

9 hours ago, Stuart Galbraith said:

Well, I think they were reliably working in British service by 1941, so I think 'years' was an exaggeration on their part. 

I dont doubt you are right, but to me that is even more incomprehensible. They listen to the RAF about putting Merlins in Mustang. They listen to the RAF about building lighter airframes. They listen to the RAF about Radar, but for some reason, it completely seems to miss their attention the RAF have cannons, and they have been working reliably for years.

 

It turns out reverse engineering is very hard.  Recall Bojan's posts on Yugoslavian MG-42 production.  Sometimes it goes very well, like the American made Bofors, and sometimes it doesn't.

[Markus Becker]

1 hour ago, R011 said:

It turns out reverse engineering is very hard.  Recall Bojan's posts on Yugoslavian MG-42 production.  Sometimes it goes very well, like the American made Bofors, and sometimes it doesn't.

The US or the UK for that matter didn't reverse engineer the HS404, they got a license. 

[R011]

1 minute ago, Markus Becker said:

The US or the UK for that matter didn't reverse engineer the HS404, they got a license. 

I know.  Close enough.

[Markus Becker]

That came with a technical data package, so it should have been a straightforward case of conversion from metric. Something the UK managed.  

Didn't the UK have a license for the Bofors too? Via the British Army? 

[R011]

9 minutes ago, Markus Becker said:

That came with a technical data package, so it should have been a straightforward case of conversion from metric. Something the UK managed.  

Didn't the UK have a license for the Bofors too? Via the British Army? 

Conversion from metric.  Conversion of drawing perspectives.  Adaptation to US production methods abd available materials and tooling . . .