14.5mm vs. 12.7 (50 cal) vs. 23mm

[gottschs]

I always wondered why the Russians skipped over the 14.5mm and went to the 12.7mm or 23mm for aircraft weapons.

The 14.5mm has a very flat shot (as opposed to the way the 23mm arc'd) and it hit much harder than the 12.7mm.

I realize the use of machine guns of the 7.5-7.9mm were very useful for volume shooting versus manpower.

Just wondering.

 

[tomo pauk]

VJa-23 was firing a 200g shell at 900 m/s at 550-650 rd/min, weight 66 kg. I don't see why should we characterize the 23mm as a cartridge with arcing trajectory.

 

[rinkol]

The Germans made the MG 151 in both 15 mm and 20 mm sizes. After initial use of the 15 mm version in the Bf 109F2, they mostly standardized on the 20 mm version. For air-to-air combat, it would seem that the 12.7 mm or similar weapons were preferable when size and weight were important, such as in the cowling installations of lightweight fighters or operation as manually aimed guns. Otherwise, the 20 mm and larger weapons were preferred due to their superior ability to benefit from explosive shells

 

[Shortround6]

Gentlemen, the reasons for skipping over the 14.5mm cartridge for aircraft weapons are relatively simple.

From Anthony Williams website. BOOKS BY ANTHONY G WILLIAMS

U.S. .50 cal on the left. Russian 12.7X108 is the 6th. German 15mm MG 151 round ins 8th and the Russian 14.5x114 is on the right.
You need a large and heavy gun to fire the 14.5mm round and barrels are going to get shot out rather quickly.
If you can put a 23mm cannon into the plane for about the same size and weight and if you can store about the same number of rounds of 23mm ammo in the space available (weight is different) why would you use the 14.5mm round?

The machine gun the russians developed for it weighs 49kg and fires at 600rpm. A dedicated aircraft gun might well be somewhat lighter and faster firing (and break more often) but the 14.5mm HE I projectiles weigh about 1/2 as much as a 20mm and 1/3rd as much as a 23mm projectile.

 

[Koopernic]

I always wondered why the Russians skipped over the 14.5mm and went to the 12.7mm or 23mm for aircraft weapons.

The 14.5mm has a very flat shot (as opposed to the way the 23mm arc'd) and it hit much harder than the 12.7mm.

I realize the use of machine guns of the 7.5-7.9mm were very useful for volume shooting versus manpower.

Just wondering.

It would be interesting to see the Soviet Russian arguments for skipping over the 14.5mm gun. It's worth looking at the German experience.

When the Me 109F1 was introduced it also introduced the MG 151 canon with a calibre of 15mm. This gun has a very high muzzle velocity and was explosive filled. It replaced the 20mm MG FF/M on the Me 109E7. Me 109E1-E3 were armed with the MG FF and from the Me 109E4 onwards the MG FF/M which was the same gun with minor modifications to fire the lighter and faster Minenengeschuss which were thin walled and filled with more explosives.

The MG 151 15mm was liked by many pilots who were good shots, its long range, accuracy and flat trajectory allowed them to get high hit rates. The MG 151 15mm however not so good for average pilots who could not get as high a percentage of hits and I suspect it did not perform well against bombers and soon most MG151 were the MG 151/20 which had a much heavier round with more explosive filler fired at a still respectable velocity.

In the same way that the Germans necked out their 15 x 104 mm to 20 x 104 the Russians necked out the 14.5 x 115 to create 23 x 115. So, in a way, they made the same decision as the Germans.

The MG 151/15 was equal to the Soviet 14.5mm in ballistics. The MG 151/20 had inferior ballistics but they were still good to 500m and had a much more destructive shell.

The VVS however made little use of the 23mm except on some ground attack aircraft. They used 20mm ShVak and 12.7mm (which could replace 7.62 in most cases)

So the Russians would have face the same problem: the 14.5mm gun was accurate and had good ballistics but not enough destructive power for the weight carried in an aircraft.

The 23mm gun was significantly more powerful than the MG 151/20 in terms of muzzle velocity and shell weight and in fact the British variants of the Hispano were also more powerful than the MG 151/20 in terms of velocity.

The other problem with the 14.5mm gun is that its just too big to be used on a flexible mount and to fit into locations such as an synchronised engine mount.

For instance the German 13.2mm MG 131 with its 13.2 x 64mm round was less powerful than the US 50 or Russian 12.7 or 14.5 but its strength was an much higher firing rate than these guns and the fact it could replace 7.92 mm rifle calibre guns in compact nose mounts yet had 2-3 more times the destructive power and penetration than rifle calibre. In fact the bullets could be explosive filled.

The Soviet 14.5mm seems to have developed as an AT gun round to replace or supplement the 12.7mm. When converted into a machine gun it was too heavy for troops. It was found very useful for Anti Aircraft use. This weapon was an army weapon and just not ready until mid war, it entered service as an AAA weapon in 1944.

The German 2.0cm FLAK C30 and C38 had different rounds and cartridges to the MG 151/20 both much heavier and with much higher velocity. I don't believe they were ever used in an aircraft.

If the Germans needed FLAK they used their MG 34 or MG 42 with the tripod (which was an effective AAA mount) or they upsized to the 2.0cm C38 in a hand cranked, geared heavy mount that guaranteed accuracy for the massive recolil.

Another issue was likely synchronisation. German MG 151 and MG 131 could be electrically synchronised via electrical primers. The Russian 23mm gun could be synchronised (I suspect hydraulically). A synchronisation mechanism may just not have been worth developing.

The MG 151/15 seemed to still show up in some German aircraft projects eg Dornier Do 335 because its ballistics matched the larger Mk 103 30mm canon.

MG 151/20 were used for FLAK but only because of a shortage of C38 guns.

The 14.5mm barrel would also have been long compared to the 23mm, difficult to install.

 

[Aurum]

You are absolutely wright, dear K Koopernic

But there are some corrections )
1)

The German 2.0cm FLAK C30 and C38 had different rounds and cartridges to the MG 151/20 both much heavier and with much higher veolocity. I don't believe they were ever used in an aircraft.

In fact there was a attempt to convert 2.0cm FLAK C38 into the aircraft weapon performed by Rheinmetal. Cannon had designation MG C/30L (MG.102). There is nice story, pics & tech. data of its construction but in russian.

2)

If the Germans needed FLAK they used their MG 34 or MG 42

FLAK - thats a cannon but not machine-guns i.e. 2 cm [Flak 30 & 38], 3.7 cm [Flak 18, 36, 43], 5 cm [FlaK 41], 5,5 cm [Gerat 58], 3 cm [Flak Mk103] ets.

 

[swampyankee]

Tony Williams has published several articles about this. See his website (BOOKS BY ANTHONY G WILLIAMS) and, for example, these articles:
" The Development of RAF Guns and Ammunition from World War 1 to the Present Day" (RAFHS 08)
" CANNON OR MACHINE GUN? The Second World War Aircraft Gun Controversy" (CANNON OR MACHINE GUN)
"WORLD WAR 2 FIGHTER ARMAMENT EFFECTIVENESS" (WORLD WAR 2 FIGHTER GUN EFFECTIVENESS)

There's a reason that pretty much everybody abandoned heavy machine guns as aircraft armament by 1950. The question is why anybody kept using them.

 

[Koopernic]

You are absolutely wright, dear K Koopernic

But there are some corrections )
1)
In fact there was a attempt to convert 2.0cm FLAK C38 into the aircraft weapon performed by Rheinmetal. Cannon had designation MG C/30L (MG.102). There is nice story, pics & tech. data of its construction but in russian.

2)

FLAK - thats a cannon but not machine-guns i.e. 2 cm [Flak 30 & 38], 3.7 cm [Flak 18, 36, 43], 5 cm [FlaK 41], 5,5 cm [Gerat 58], 3 cm [Flak Mk103] ets.

I spent 2 moths learning Russian with Babel while working on a mine in Siberia, not good enough for this excellent article. Once I learned Cyrillic I had an epiphany and understood how close European languages are with each other. The Google Translate version comes out very well:
Google Translate

I hadn't realised but WW2 Russia developed two 23mm cartridges. The 23 x 114mmm (which came out of the 14.5 x 114 ) associated with the NS 23 autocannon and modern NR 23 and the far more powerful 23 x 152 associated with the Volkov-Yartsev VYa-23 autocannon used on IL-2 and IL-10 Sturmovik though they did manage to squeeze them on variants of the Yak 9 and LaGG 3. All these cartridges are still in use today.

The problem with the 20 x 138 based MG C/30L (MG.102) for use on aircraft was probably not the weight (70kg) but the fact that it was a recoil operated mechanism that was therefore slow firing since the extra recoil needed to operate extraction slows the rate of fire as the cartridge gets longer. Slow firing is OK for FLAK where sustained fire is important and multiple guns can be used. The solution was gas operation, which both the Russian guns used as did the allies on the Hispano. The Luftwaffe seems to have focused on the 3.0cm Mk 103 as the next size up and which was gas operated but at 140kg was too big for the wing roots of the Fw 190. It could fit into the wing roots of the Ta 152 and it seems could be used as a motor canon on Ta 152 and Fw 190D series (experimental installation). It was possibly a mistake since the Fw 190F9 could dive attack at 60 degrees and the 20 x 138 should have been a threat to all allied tanks except maybe IS-2.

In Luftwaffe terminology anything at or under 2.0cm was a machine gun and that above a machine canon. Rather redundant. I think the terms C30 and C38 are German naval designations representing the year of acceptance into service. The designations seems to have made it over into FLAK terminology used by the Army (or Luftwaffe since the Luftwaffe provided most of the German Armies FLAK till 1944 or so) So either the Germans themselves mixed the designations when the weapon was adopted by another service or post war allied historians mangelled it.

The Luftwaffe did start to develop the MG 213 revolving breech autocannon and its said it was to offer 1000 m/s velocity, 1000 rpm cadence and 1000m range. That sort of performance could only have come from a cartridge of the same power as the 20mm x 138 and it seems they used a 20 x 135 cartridge.. It would have been hard work introducing a new ammunition type so I expect the round might have been the same, as the MG 213 could be synchronised to fire through a propeller and thus in the German system an electrical primer might be needed. The advantage of revolving breeches is the resistance to jamming gas and recoil guns have.

 

[gottschs]

The other problem with the 14.5mm gun is that its just too big to be used on a flexible mount and to fit into locations such as an synchronised engine mount.

The 14.5mm barrel would also have been long compared to the 23mm, difficult to install.

Thanks for the feedback all. So the 14.5mm would be too large or barrel to long for a spinner mount in an in-line engine (e.g., DB or Merlin)? And the recoil would be too much for a wing mount...for example in a P-36?

 

[tomo pauk]

Thanks for the feedback all. So the 14.5mm would be too large or barrel to long for a spinner mount in an in-line engine (e.g., DB or Merlin)? And the recoil would be too much for a wing mount...for example in a P-36?

My take:
- no, the barrel of the 14.4mm machine gun will not be too long for the 'spinner mount'
- recoil of the 14.5mm will be lower than of non-Oerlikon-based 20mm cannon (talk MG 151, Shvak, let alone Hispano)
- we can recall that French were using the Hispano in flexible mounts, so the 14.5mm will not be that far fetched

 

[swampyankee]

My take:
- no, the barrel of the 14.4mm machine gun will not be too long for the 'spinner mount'
- recoil of the 14.5mm will be lower than of non-Oerlikon-based 20mm cannon (talk MG 151, Shvak, let alone Hispano)
- we can recall that French were using the Hispano in flexible mounts, so the 14.5mm will not be that far fetched

Considering that the Soviets had through-hub 37mm and 45mm guns, I'd not think the 14.5 mm would be "too long" or "too large."

Note that the Germans had a perfectly serviceable 15 mm MG and pretty much completely replaced it with a 20 mm created by necking out the cartridge, I'd say that pretty much everybody -- except the USAAF* -- were of the opinion HMG were not the best choice.


---------------

* And the USAAF's opinion my have been biased by the massive problems the US had in getting a 20mm aircraft cannon into production.

 

[Koopernic]

Thanks for the feedback all. So the 14.5mm would be too large or barrel to long for a spinner mount in an in-line engine (e.g., DB or Merlin)? And the recoil would be too much for a wing mount...for example in a P-36?

I was thinking of the problem in wing mounting. The Hispano was developed as a "motor canon" by the French as it was actually quite long to clear the spinner with the breech behind the gun. The British (and US?) licensed produced it but found that because the barrels produced well ahead of the leading edge they created much drag. Although they developed all sorts of streamlining shrouds the ultimate solution was to reduce barrel length. I don't know how this effected ballistics.

The P-51A looked mean with those 3 Hispano's sticking out.