Alternative airborne guns 2.0

[tomo pauk]

My hypothetical "ideal" ammo is the 20x110 upnecked to 23 mm.
135-gram mineshell with 30 gram PETN 850 mps, with more conventional shell as backup: 175 gram with 20 gram PETN, 750 mps.
Germans could use 24x138 mm, but mentioned earlier 30x111 analog (let's call it 30x110RB) would be the best option.

My hypothetical "ideal" ammo is the 20x110 upnecked to 23 mm.
135-gram mineshell with 30 gram PETN 850 mps, with more conventional shell as backup: 175 gram with 20 gram PETN, 750 mps.
Germans could use 24x138 mm, but mentioned earlier 30x111 analog (let's call it 30x110RB) would be the best option.

In order not to clutter the 'P-39 mondial' thread, here is a thread about the alternative guns of 1935-45. To spice it up - let's say that the historical heavier guns are exception, while the new norm should be the alternative guns at your liking. So - the Hispano cannon is merely a footnote, Germans don't buy the MG FF, Soviets make a faster move away from the Shvak, Italians make something else besides the Breda LMG and HMG etc.
Anything between 7mm and 60mm is in the play, to deal with the suitable targets in the air and on surface, with extra points for coming out with the gun(s) that can actually fit on the existing aircraft, especially on the 1-engined fighters of the day.
Extra points also for keeping the guns simple, on the tech level of that decade.

 

[bf109xxl]

That is almost like a Soviet 23x115 with a 200 g projectile.
One of the clearest examples of the inefficiency of the Soviet system. The Soviets could have a near-perfect gun for WWII conditions as early as 1941, but they executed the designer and barely started production of his slightly modified gun in 1944 instead...

 

[tomo pauk]

The 'west' in general might've also put the 23mm in their arsenals, with the Madsen 23mm being a know quantity in the late 1930s. The 174g HE shell was fired at 720m/s, while the gun was belt-fed - checks all the boxes, IMO. Gun was not overweight (just to the contrary), the 400 rd/min RoF was not the worse thing in the world considering the potent shell and the modest gun weight.
Hispano were also working on the 23mm gun, but the downfall of 1940 put the stop on that.

Another country that might've benefitted from necking-out the 20mm stuff to 23mm (like what Madsen did?) was Japan, with their very powerful 20 mm cartridges/guns used by the IJA. The more potent shells would've cancel out the main shortcoming of the Ho-1/-3 guns, these being the sedate RoF of some 400 rd/min.
The really big 20x142mm cartidge would've probably do well if necked-out to 25mm; granted, a gun should've also been made for it
FWIW

 

[bf109xxl]

The 'west' in general might've also put the 23mm in their arsenals, with the Madsen 23mm being a know quantity in the late 1930s. The 174g HE shell was fired at 720m/s, while the gun was belt-fed - checks all the boxes, IMO. Gun was not overweight (just to the contrary), the 400 rd/min RoF was not the worse thing in the world considering the potent shell and the modest gun weight.

Yeah, the ammunition is pretty much the same parameters. The gun itself was still a bit heavy (55 kg vs. 36 kg of NS-23) and the rate of fire was still required to be higher. But in general I agree - it is almost ideal in terms of ammunition.

Another country that might've benefitted from necking-out the 20mm stuff to 23mm (like what Madsen did?) was Japan, with their very powerful 20 mm cartridges/guns used by the IJA. The more potent shells would've cancel out the main shortcoming of the Ho-1/-3 guns, these being the sedate RoF of some 400 rd/min.

The Soviets used even 14,5 mm cartridge (14,5x114) for 23 mm. This indicates a wide range of possibilities for developing 23mm caliber ammunition.

The really big 20x142mm cartidge would've probably do well if necked-out to 25mm; granted, a gun should've also been made for it
FWIW

The experience of the Soviet VYa with 23x152 ammunition was rather negative - the gun had too strong recoil and was unsuitable for fighters.

 

[tomo pauk]

Yeah, the ammunition is pretty much the same parameters. The gun itself was still a bit heavy (55 kg vs. 36 kg of NS-23) and the rate of fire was still required to be higher. But in general I agree - it is almost ideal in terms of ammunition.

The gun was also available some 4 (5?) years before the NS-23 - that is eternity in the context of the ww2.

The experience of the Soviet VYa with 23x152 ammunition was rather negative - the gun had too strong recoil and was unsuitable for fighters.

The VJa-23 and the "VJa-25" would've been far more suitable for the fighters than the NS-37. From standpoint of the recoil, size, RoF and mass.

 

[bf109xxl]

The gun was also available some 4 (5?) years before the NS-23 - that is eternity in the context of the ww2.

The NS-23 was just a further development of the PTB-23 by Taubin. The development of the latter started in 1938.

The VJa-23 and the "VJa-25" would've been far more suitable for the fighters than the NS-37. From standpoint of the recoil, size, RoF and mass.

The recoil of the 11P gun (future NS-37) was about the same as that of the VYa in ground tests. And in general, the NS-37 was not the best choice for a fighter.

 

[tomo pauk]

The NS-23 was just a further development of the PTB-23 by Taubin. The development of the latter started in 1938.

There is nothing that stops the western or Japanese competent people to further develop on the 23mm Madesn cartidge, too. Like making new and better guns for it, just like they did for different 20mm ammo.

The recoil of the 11P gun (future NS-37) was about the same as that of the VYa in ground tests.

Was it?

And in general, the NS-37 was not the best choice for a fighter.

Hence (but not just because of it) this thread.

 

[bf109xxl]

There is nothing that stops the western or Japanese competent people to further develop on the 23mm Madesn cartidge, too.

Sure. I just mentioned that the story of the NS-23 began much earlier.

Like making new and better guns for it, just like they did for different 20mm ammo.

But nobody did it indeed! It is a bit surprising to me.

Was it?

Yes, the value of 5500 kg was measured for both the guns. But the Soviets had problems with the methodology of the tests - there was no full understanding of how to measure correctly. Therefore, the results of measurements sometimes differed radically. Ground tests of the 11P in 1944 showed recoil force from 4050 to 4750 kg, depending on the fluid and adjustment of the recoil brake. If I'm not mistaken, the pilots thought that the 11P had a weaker recoil than the VYa. The power of the VYa ammunition was obviously excessive.

While the effectiveness of 23 mm guns against bombers is not in doubt, their effectiveness against fighters is not quite obvious to me. Taking into account the ammunition capacity of about 75-100 shells per barrel and high rate of fire, I cannot draw a definite conclusion.

 

[tomo pauk]

Yes, the value of 5500 kg was measured for both the guns. But the Soviets had problems with the methodology of the tests - there was no full understanding of how to measure correctly. Therefore, the results of measurements sometimes differed radically. Ground tests of the 11P in 1944 showed recoil force from 4050 to 4750 kg, depending on the fluid and adjustment of the recoil brake. If I'm not mistaken, the pilots thought that the 11P had a weaker recoil than the VYa. The power of the VYa ammunition was obviously excessive.

You will excuse my skepticism wrt. the conclusion that recoil of the VJa-23 and NS 37 were in the ballpark.

While the effectiveness of 23 mm guns against bombers is not in doubt, their effectiveness against fighters is not quite obvious to me. Taking into account the ammunition capacity of about 75-100 shells per barrel and high rate of fire, I cannot draw a definite conclusion.

It depends on who has the gun, and who is the enemy.
For the Soviets, Germans and Japanese, the big-ish gun made good sense. For the Americans and the British, less so.
75-100 shells for the cannon was very tall order for most of the folks before 1941.

 

[bf109xxl]

You will excuse my skepticism wrt. the conclusion that recoil of the VJa-23 and NS 37 were in the ballpark.

The recoil of the VYa was considered by the Soviets to be too high, because of its very high muzzle velocity - almost 900 m/sec. Even with the same ammunition, the MP-6 of Taubin design had much lower recoil.

Depends who has the gun, and who is the enemy.

Agree.

75-100 shells for the gun was very tall order for most of the folks before 1941.

La-9 pilots, for example, did not complain about too little ammunition. I have a feeling that the difference was only in the ingrained stereotypes. If pilots were trained from the beginning to use such ammunition, the opinion might be changed.

 

[tomo pauk]

The recoil of the VYa was considered by the Soviets to be too high, because of its very high muzzle velocity - almost 900 m/sec. Even with the same ammunition, the MP-6 of Taubin design had much lower recoil.

Recoil is dependent on the projectile weight as much as it is dependent on the muzzle velocity. The heavy 37mm shell, that was also fired at high MV, is bound to produce a much higher recoil than the 200g 23mm shell, that is also fired at high velocity. A gun that is heavier will lower the recoil, the heavier the better (but not better if we want to have the gun installed on a small fighter, so some compromise need to be found).
With that said - sometimes the gun recoils 'worse' than the other because one designer team used different operation system, and/or opted not to install recoil-reducing devices, like the recoil buffers or additional springs, and/or muzzle brake. Eg, when compared for single-shot, the recoil of the Johnson LMG was vicious, while that of the FG 42 was mild, despite the later being a lighter gun. So it is very much possible that the reciprocating parts of the VJa-23 were allowed to slam on the end of the receiver at the end of the travel, while Taubin perhaps took care of that problem already in the design phase?

 

[bf109xxl]

Recoil is dependent on the projectile weight as much as it is dependent on the muzzle velocity. The heavy 37mm shell, that was also fired at high MV, is bound to produce a much higher recoil than the 200g 23mm shell, that is also fired at high velocity. A gun that is heavier will lower the recoil, the heavier the better (but not better if we want to have the gun installed on a small fighter, so some compromise need to be found).

Yes, of course. But it's the recoil that is transferred to the gun, with a recoil brake you can reduce the force transferred to the mount. To reduce the recoil the VYa required recoil dampers on the carriage, which made it bulky. And the 11P was actually of Taubin's design - Nudelman was Taubin's second-in-command and saved his designs for the future developments.

So it is very much possible that the reciprocating parts of the VJa-23 were allowed to slam on the end of the receiver at the end of the travel, while Taubin perhaps took care of that problem already in the design phase?

Taubin paid more attention to the recoil problems. The MP-6 gun's automatics operated much smoother than those of the VYa, and the weight of the gun was considerably less. Nevertheless, even with a very good gun design, only the switch to the 23x115 ammunition with reduced power instead of 23x152 allowed to change the situation radically and create a gun with the required characteristics. The Madsen were visionaries, but they were not appreciated properly.

 

[tomo pauk]

Options for Germany:
- a HMG designed around the 13.2x92 cartridge, ie. the rimless spin-off of the known 13.2mm TuF
- a 'MG 151/23' - scaled-up MG 151 cannon to fire the 23mm ammo (that can be derived from that of Madsen); talk a 50-60 kg gun, 700+- rd/min, ~150g M-shell
- a 'MK 102' - about a 100 kg heavy gun, that uses the 25mm full-power ammo akin to that of the French 25mm AA gun; 500 rd/min, ~200g M-shell at 950 m/s

More later.

 

[ThomasP]

I have always wondered bout the Besa 15mm for a what-if.

Heavier than the .50 cal Browning Aircraft Gun (at 121 lbs vs 64 lbs for the .50 cal Aircraft Gun), firing a heavier projectile (1160 grain vs 700 grain) with a similar MV of 2700 ft/sec. Belt-fed with a high ROF of 750-850 rpm (similar to the mid- to late-war .50 cal Browning) and already in production in 1940 in its AFV version.

Maybe too heavy for early-war fighters in its AFV version, but it could probably be lightened a bit. And it could have useful AP/I, Incendiary, and HE rounds.

[edited]

 

[peceed]

Clean-sheet alternative history without restrictions is not that interesting.

Germany: Skipping Oerlikons, faster introduction of MG 151/20, then faster introduction of MK 108, using a "preincarnation" of the 30x111mm (72 kJ) cartridge with Minengeschoss shells.

France: faster introduction of HS.406. Its ammo - 23 mm, 200 g, 900 mps (81 kJ), could be up-necked to use 25 mm shells. Then they can copy German Minengeschoss projectiles, up-necking again (to 27 - 30 mm).

USA: In 1936 Browning created the 12.7 mm M3 gun, with a built-in conversion option (by a barrel swap) to a new 16 mm cartridge - upnecked variant of 0.50.
60-gram shell elaborated by around 6 grams of HEI (the same as Soviet 20x99mmR!) reaches 792 mps (2600 fps). With 1200 rpm it is a formidable competitor for historical 20 mm guns.

Poland: Considering all financial and operational constraints (single cartridge for AT, AA and aircrafts was strongly preferred), the optimal solution was to get a license for Oerlikon FFS as early as possible, simplify it (POLSTEN) and create a domestic mechanism for belt feeding. Then create lighter and faster firing FK-38D for fighters.

Japan: Just force standardization between different branches of the military.

 

[Shortround6]

I have always wondered bout the Besa 15mm for a what-if.

Already in production in 1940 in its AFV version. Heavier than the .50 cal Browning Aircraft Gun (at 121 lbs vs 64 lbs for the .50 cal Aircraft Gun), firing a heavier projectile (1160 grain vs 700 grain) with a similar MV of 2700 ft/sec. Belt-fed with a high ROF of 750-850 rpm (similar to the mid- to late-war .50 cal Browning) and already in production in 1940 in its AFV version.

Maybe too heavy for early-war fighters in its AFV version, but it could probably be lightened a bit. And it could have useful AP/I, Incendiary, and HE rounds.

It is best handled by the department of redundancy.

By the time you make and install the 15mm Besa you could have built/installed a 20mm Hispano.

The Rim and back end of the case was within 0.1-0.2mm of the size of the 20mm Hispano case. The 20mm H-S used less taper and a lot less neck.
20mm H-S fires a much bigger diameter (and heavier) projectile at a similar velocity. Obviously a 15mm HE shell has about the same number of pieces and manufacturing operations as a 20mm shell. Very little savings in either brass or propellent.
As an AP round it has some advantages, as an HE round it has none.

 

[Shortround6]

7.62x56r
German 13.2x92r
US .50 cal 12.7x99
British .55 Boys
12.7x108
14.5x114
French used the US .50 cal necked up to 13.2 and with a 96mm long case.

For the Germans there was no manufacturing base left for the 13.2x92 cartridge. Might as well design something new and better (less taper, sharper neck).
And decide what you want. The German 13x64 and the Vickers 12.7x81 offered smaller/lighter guns than the bigger cartridges, not always acted upon.

World War 2 Fighter Armament Effectiveness

Anthony G Williams & Emmanuel Gustin (with acknowledgements to Henning Ruch) The comparative effectiveness of fighter guns in the Second World War is a subject of perennial fascination (and a g…

flying-guns.com

Has got pictures of most of the cartridges used.
The pictures are not the same scale. The last cartridge on the right of a picture is the first cartridge on the left of the picture below it.

Recoil is generated by mass times velocity of the 'stuff' going out the muzzle. Projectile mass x velocity + propellent mass x velocity. This NOT the energy of the projectile. The velocity of the escaping gas is much closer between guns than the velocity of the projectiles and it is much higher than the veleocity of projectile/s. For estimates you can use a constant. This gives you the recoil impulse

Recoil of the gun gets tricky. You do have to deal with the recoil impulse somehow. But the actual recoil impulse of the gun depends on the weight of the gun which affects the velocity of the gun's recoil. The force can be distributed over time/distance.
API guns use some of the recoil to counteract the force of the breech block moving forward (and/or barrel also moving forward).
On some of these large guns there is a peak recoil force and a total recoil force. A longer distance traveled by the gun (or a large part of it like the barrel) spreads out the total force in time and lowers the peak force. Makes things easier on the mount/aircraft. But this can slow down the rate of fire of the gun. Abrupt starts and stops, as noted by others, can also affect the recoil forces transmitted to the structure.

 

[tomo pauk]

British:
- not giving the .50 HMG a try was a mistake IMO, so this time around they should've try it - there is no reason that each Hurricane and Spitfire already by 1938 could not be armed with 4 HMGs, that each weapon is at least an equivalent of the Italian HMG; the HMG will also be a much better self-defense weapon than a LMG of the era
- as a step up - buy 20mm guns at Oerlikon for the RAF, too, not just for Army and RN; T. WIllians favored (and he still is, if I'm not mistaken) the FFL - again, the Oerlikons should've been available earlier than the Hispano

Germans again, with an obvious accent to the Mine shells:
- MK 103/37 - the spin off on the basic MK 103 design, that fires a 37mm M-shell of 550g at some 700 m/s (the 'normal' M-shell ammo for the BK 3.7 was fired at ~915 m/s) and at ~400 rd/min; also useful for armor-piercing job when provided with APCR ammo, that weighted 410g for the BK 3.7
- MK 108/25 - a way to utilize the 25mm barrels from the thousands of 25mm ATGs captured in France, that were being hopelessly outdated by 1941; a 70-80 kg gun, firing perhaps a 200 g M-shell at well over 900 m/s by the propellant charge of some 60g - basically, ballistics close to that of the VJa-23; bonus - should be also very useful as an AA gun

 

[yulzari]

It is best handled by the department of redundancy.
View attachment 803527
By the time you make and install the 15mm Besa you could have built/installed a 20mm Hispano.

The Rim and back end of the case was within 0.1-0.2mm of the size of the 20mm Hispano case. The 20mm H-S used less taper and a lot less neck.
20mm H-S fires a much bigger diameter (and heavier) projectile at a similar velocity. Obviously a 15mm HE shell has about the same number of pieces and manufacturing operations as a 20mm shell. Very little savings in either brass or propellent.
As an AP round it has some advantages, as an HE round it has none.

Which makes perfect sense as the 15mm BESA was developed exactly for the AP role. Ground or vehicle mounted.

Hence the British preference for using it on armoured cars in semi automatic fire for accuracy. Necking it up to 20mm for HE would indeed be reinventing the wheel. By late in the war they were abandoning it as they had literally shedloads of American 37mm guns taken off obsolete armour so went over to mounting those instead as a simple route to HE etc fire.

Not unlike the Sudanese AEC ordered Staghound armoured cars with AEC turrets instead the Staghound 37mm ones.Gluing Sherman 75mm mantlets and guns onto the AEC turrets as the ROF QF75mm guns and mounts normally used were no longer available. But that was more an alleged story of corruption than of tactical planning.

 

[peceed]

not giving the .50 HMG a try was a mistake IMO, so this time around they should've try it - there is no reason that each Hurricane and Spitfire already by 1938 could not be armed with 4 HMGs, that each weapon is at least an equivalent of the Italian HMG;

You can't judge a weapon in isolation from the quality of the ammunition available.
The .50 only reached its maximum effectiveness when the design of the Soviet BS-32 armor-piercing incendiary shell was copied, and then its firepower doubled. This clearly shows that previously they could not have been very effective, and so it turned out in the British tests. The effectiveness of the larger shells was not much greater than those already in possession, and in the same mass it was possible to have a weapon firing 4 shells instead of one.
Actually, I think that the Americans in the Pacific would benefit greatly from replacing their .50 with double the amount of .30 with British armor-piercing incendiary ammunition - thanks to the lack of protection in Japanese aircraft.

a step up - buy 20mm guns at Oerlikon for the RAF, too, not just for Army and RN; T. WIllians favored (and he still is, if I'm not mistaken) the FFL - again, the Oerlikons should've been available earlier than the Hispano

And they should quickly make long 4 row magazines for 100 shells. Length around 80 centimeters is quite managable.

- MK 103/37 - the spin off on the basic MK 103 design, that fires a 37mm M-shell of 550g at some 700 m/s (the 'normal' M-shell ammo for the BK 3.7 was fired at ~915 m/s) and at ~400 rd/min; also useful for armor-piercing job when provided with APCR ammo, that weighted 410g for the BK 3.7
- MK 108/25 - a way to utilize the 25mm barrels from the thousands of 25mm ATGs captured in France, that were being hopelessly outdated by 1941; a 70-80 kg gun, firing perhaps a 200 g M-shell at well over 900 m/s by the propellant charge of some 60g - basically, ballistics close to that of the VJa-23

Conversely. From the barrels of the 25 mm guns, the MK 103/25 variant should have been made, which would be at least as effective as the original, because the smaller caliber would allow for a lighter sabot.

In turn, for the aforementioned 37 mm shells, the enlarged MK 108/37 cannon could be adapted, which would weigh about 140 kg, have a rate of fire of 450 rpm and operate on 37x140mmRB ammunition.