AA guns + rockets alternatives for 1935-45

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tomo pauk said:
BTW - is there any worth in making the 50-57mm automatic guns for the 1935-45 period, with the (perhaps false) premise that each of these produced means the two of the 37-40mm automatics don't get produced?
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You may be close, estimating costs based on weight in action a bit questionable but it is all that we have.
As to the worth, the Germans tried 2-3 times and the first try, the 5cm Flak 41 showed that while such a gun was desirable, the 5cm Flak 41 was not it.

5 cm Flak 41 - Wikipedia

en.wikipedia.org

Ian V. Hogg's book on German Artillery says.
"It was unstable when fired, the center of gravity was so high it was also unstable when being towed, it was difficult to conceal, it could not track targets fast enough, the sight was too complicated and was a poor calculator in the Bargain."
Hogg's book has some different numbers than Wiki in that it shows emplaced weight and practical rate of fire (130rpm) and a much more optimistic effective range.


The 5.5cm Flak Ger 58 was a gold plated, cost is no object, goal was 100% destruction using a 6 gun battery defending high value targets. This never made it into service.
This started when the Germans discovered the 5cm shell size was unsuited to the job needed. It was impossible to design/build a shell that held the desired amount of explosive that would remain stable at the high velocities demanded. Back to the drawing board and the move to the 5.5cm shell size.

The only other examples are the post war Bofors 57mm guns and the Soviet post war 57mm guns.
US and British pretty much jumped right to 75-76mm guns using proximity fuses.
The British did have a long and torturous path with the 6pdr 6cwt AA gun (which only shares bore size with the host of other British 6pdr guns) and would up with a twin gun that weighed over 24,000lbs in action and managed 35 rpm per barrel when everything worked right, which it much more often than not didn't.
This Path took from the Idea in 1940 to the specification in Jan 1941 finally, after many twists and turns to the cancelation on March 30th 1945.
Work on a single barrel continued for a while after the war that lead to good information on high speed loading systems but not much else.
 

Germans perhaps reckoned that, as far as the automatics go, their 37mm lacked the oomph with the 640g shell @ 820 m/s?
My pet 'project' would've been that they make a modern gun for the powerful Navy's cartridge (750g shell @ 1000 m/s) by the late 1930s. There was such a project by the time war was on, named 'Geraet 341', made in 4 copies per Waffen Revue 46, but it remained stillborn. Cyclic RoF of 250 rd/min, the main problem was the increased barrel wear (a combo between the very high RoF, high pressures and temperatures and an low-quality barrel material saw to it). The 4 guns were tested between mid-1943 and mid-1944.

To move upwards with the caliber brackets:
For the 75-105mm guns, a shell with the rocket boost might offer a feasible way to increase the reach without the need for going one step up with the gun calibre, size, weight and price. Nothing flashy and big, but just a way to add another 100-150 m/s to the MV?
 
tomo pauk said:
Germans perhaps reckoned that, as far as the automatics go, their 37mm lacked the oomph with the 640g shell @ 820 m/s?
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Step one. Hit the target.
Step two, Worry about the effectiveness.
We also have to balance a number of factors. The German 3.7cm naval gun was a real side track down a dead end siding. At least for around 10 years.
Gun......................................................shell weight.......................propellent weight.......................MV..........................rate of fire
G. 37mm Flak 36...................................644g......................................175g........................................820m/s.......................160-180(?)
G. 37mm Flak 42...................................644g......................................175g........................................845m/s.......................160-180(?) got a longer barrel
G. 37mm Flak 43...................................644g......................................190g........................................820m/s.......................250rpm
G. 37mm SKC/30...................................748g.......................................365g....................................1000m/s..........................30rpm
40mm Bofors..........................................955g.......................................303g......................................820m/s........................160rpm

Now in all cases the rate of fire is the maximum and actual rate of fire could be a lot lower. 40mm Bofors figures are for the gun in German service.
Please note that the Americans and British navies both used water cooled and air cooled 40mm Bofors guns to solve the cooling problem for guns firing for long periods of time vs guns that were weight limited.
You can try to solve the heat problem with spare barrels, brave men and asbestos gloves.
German 37mm SKC/30 also used a 80-83 caliber length barrel, and that much weight that far out hurts elevation and traverse and smooth tracking.
I will also note that if you scaled a German 644g shell up to 40mm you would have an 813g shell. If you scale up the 748 gram shell you get 942 grams.
Granted the 40mm Bofors may not have ideal but it was available and it is hard to say that it did not work.
Germans tried for too a high a velocity in a lot of things.

It seems that the rocket motors always (or almost always) caused an increase in dispersion (loss of accuracy) even in the 1970s/80s.
The question is if the shorter time of flight make up for the increased circular error? I don't know but personally, I would not bet on it in WW II. I do have the advantage of hindsight
 
Shortround6 said:
Step one. Hit the target.
Step two, Worry about the effectiveness.
Click to expand...
Very true.
We also know that a shell of the same or similar diameter, but with ~2/3rds more muzzle energy (like the Bofors L60 and the German navy cartridge) will stand better chances to hit the target at the last kilometer of the efficient range. And/or that it might add another 500 m to the efficient range.

Shortround6 said:
We also have to balance a number of factors. The German 3.7cm naval gun was a real side track down a dead end siding. At least for around 10 years.
Click to expand...

I have not ever said that the naval 3.7cm was a good gun.
It was firing a powerful ammo, that I'd say the Germans made an omission not to make a more modern gun for.

Shortround6 said:
You can try to solve the heat problem with spare barrels, brave men and asbestos gloves.
German 37mm SKC/30 also used a 80-83 caliber length barrel, and that much weight that far out hurts elevation and traverse and smooth tracking.
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Toning down the rate of fire (it was 250 rd/min cyclic for the experimental gun) would've been my 1st suggestion. Or, tone down the propellant charge weight, say by some 10% (so the barrel can be cut down to perhaps 75 cal lengths?). Mix and match the two solutions to arrive at the optimal combination.
Even a 200 rd/min RoF gun that does 950 m/s with a 750g shell is still head and shoulders over the Flak 18.

The 40mm Bofors was probably the best of the lot, IMO.


Perhaps the users required too much from the RAP? Like increasing the range by some 40%, that required that rocket motor is about 30% of the weight devoted to the non-metal parts of the shell (ie. explosive charge is 70% of that weight). My goals are more modest, thus the negative effects of the rocket assist will also be more modest.
 
Most of these guns were good for 2000-3000meters for range. What they really needed was better sights/fire control
tomo pauk said:
I have not ever said that the naval 3.7cm was a good gun.
It was firing a powerful ammo, that I'd say the Germans made an omission not to make a more modern gun for.
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see below
Hmmm, take the 37mm x 380 case, neck it up to 40mm, Stick a Bofors shell in it and load it into modified Bofors gun. A little slow velocity but it solves several problems.
As is you are burning about 20% more propellent than the Bofors (or perhaps 15% compared to Allied loadings?).
As a guide to barrel length
Gun......................................................shell weight
G. 37mm Flak 36...................................57
G. 37mm Flak 42...................................62
G. 37mm Flak 43...................................50
G. 37mm SKC/30...................................80
40mm Bofors..........................................48

These are the length of rifling (?) The German naval Flak 42 used a longer barrel than the land Flak 36 but was otherwise similar. the longer barrel was good for about 25ms using the same powder charge, you do get diminishing returns on really long barrels. An 8mm rifle barrel that was 80 calibers in length would be 640mm long from the start of the rifling. and that is not where the cartridge case ends. There is gap between the case the start of the rifling.

The existing Flak 43 gives a much better practical rate of fire than either the old German 37mm or the Bofors gun. Doesn't need water cooling (or at least not anywhere near as much, has a short length allowing for quick traverse and elevation. See if you can push development and run with it.


Artillery tends to wobble around the axis is flight (a lot of bullets do) both nose and tail turn in small circles while the main body stays on axis with the nose and tail being on opposite sides at the same time. Like yawing. When the rocket motor kicks in the projectile will start on a new trajectory in line with where it is pointed when the motor starts up, not the original trajectory/flight path. With the projectile spinning at over 1000 rev per second (and each shell rotating slightly different to each other) there is no way to time the rocket motor start to be uniform from shell to shell. Your going to get the shells/projectiles spreading out over a wide area than the non rocket shells. Using a less powerful motor may mean less deviation but it is always going to be more than the non rocket shell of the same quality and shape.
 
Shortround6 said:
Most of these guns were good for 2000-3000meters for range. What they really needed was better sights/fire control
Click to expand...

The better the infrastructure, the more can be gotten from a gun.
Having a better gun still helps, though. Americans had no problems in admitting that the 40mm Bofors was a better gun than their 37mm piece, and acted accordingly.
Shortround6 said:
Hmmm, take the 37mm x 380 case, neck it up to 40mm, Stick a Bofors shell in it and load it into modified Bofors gun. A little slow velocity but it solves several problems.
Click to expand...
if we're taking the whole Bofors gun and we're using it's shell, then why bother? Make a deal with the Swedes to continue the production of the Bofors & it's ammo once the Polish production line is captured (unless the Soviets have it now?), and expand from there .
The German mid/late 37mm guns were designed with the accent of fast(er) production in mind, that the Swedish product lacked. It took a lot of effort and time for the Americans to adopt the gun for the faster production, or at least the rumor has it that way.


Test the idea in the late 1930s and during the course of war. If it works - great. If not, it is not a great loss of money and effort.
 
A baby 37-40mm AA gun might've been possible for ww2. By 'baby', I mean the light and compact gun that can be used by a single gunner, but still packing a punch and range. We should keep the MV usable for an AA gun, without going to ~600 m/s as it was for the M4 gun on the P-39.

The least powerful of the new ww2 such pieces was the US 37mm - 610g shell at 790 m/s. The late 1940s Soviet N-37 was similar, firing the much heavier (~730g, same as the more powerful NS-37) shell at 670 m/s. So we might get the light shell for the Soviet gun, while the US gun will need to became somewhat lighter. Muzzle brake might help.
Soviet gun will probably need to have the RoF reduced down from 400-450 rd/min, there is no steady stream of cold air to cool it in the AA role.
Germans might want to make a sibling of the MK 101/103 in 37mm calibre. Somewhat less powerful than the 'normal' 37mm Flak; usage of the 500-550g mine shell is bound to keep the recoil low and MV high enough.
British - the 3pdr Class S gun, but with a 2pdr HE shell instead? The 3 pdr shot was doing 570 m/s, while the 1lb shot was doing 990 m/s - the 2pdr shell should be doing close to 800 m/s? Gun itself was light, while the RoF should be improved.
 
Options for the Japanese:
- buy the licence for the 40mm Bofors; Navy should be the prime user of this gun

Other guns will be less powerful, but might be worth taking a look, like the French 37mm automatic that the French don't want, or the German 37mm Flak 18, or the Breda 37mm. The 34mm Flab from Switzerland is interesting since it features the water-cooled barrel, so firing prolonged bursts will be damaging the barrel less (make a deal for a heavy barrel if this is not wanted eventually).

The low-tech approach would've bee necking-down the 2pdr to 37mm, so a 650-700g modern 37mm shell is fired instead of the 910g 40mm shell. Might have gotten the upgraded guns do 750+ m/s perhaps, and close to 800 m/s with a bit longer barrel?

Anything foreign and smaller is a flawed choice. Make the own 20mm guns, however, like the very potent Type 98 (this one would've looked good necked up to 23mm, sorta magum Madsen 23mm).
 
tomo pauk said:
A baby 37-40mm AA gun might've been possible for ww2. By 'baby', I mean the light and compact gun that can be used by a single gunner, but still packing a punch and range.
Click to expand...

Not sure what you mean?

Single gunner, as in a single person for handling everything with the weapon? Don't think that's feasible, even the USN 20mm Oerlikons IIRC had essentially a 3 man crew, 1 gunner and 2 helpers carrying ammunition from the lockers/hoists to the gun.

Secondly, for shooting beyond the range of a 20mm, can you realistically hit anything with just a spiderweb sight? Even without director control like the late war naval Bofors mounts, it seems in pictures you see one crew member wielding a rangefinder. So you might need something slightly more advanced than spray-and-pray for longer range shooting?
 
Single gun-aimer.

See the 2cm Flak, it's sights were better than just the spiderweb type. Bofors guns were also with sights that took target data from the outside source, both naval and land types. OTOH, there were 37-40mm guns that were still racking up the kills with the simple sights.

The 37mm will be much rangier, while sporting the punch better than a 20mm twin or the 25mm single, and possibly comparable with the 20mm quad. Against some SP AA that were a too small gun on a too big vehicle (like the Flak Pz38), the baby 37mm would've represented a sizable jump in both range and punch.
Last but not least, it will be better in killing lightly armored vehicles, even without the tungsten-tipped ammo.
 
tomo pauk said:
Anything foreign and smaller is a flawed choice. Make the own 20mm guns, however, like the very potent Type 98 (this one would've looked good necked up to 23mm, sorta magum Madsen 23mm).
Click to expand...
Looking at the propellant weights, the widely-used 20x138B had 40 grams + 1.5g of aux peopellant, while the Japanese Type 98 used the ammo with 59 grams of propellant.
Another powerful cartridge, the 20mm Madsen, used 41-42g; the 23mm Madsen used 34.5g to propel the 175g shell at 720 m/s. Soviet 23mm 'short' ammo was similar, while the 23mm 'long' ammo used 64g of propellant to do ~900 m/s with a 190-200 g projectile.

Basically, the 23mm Type 98 might've been halfway between the 23mm Madsen and 23mm VJa, talk about 55g of propellant to make a 185g shell go 850 m/s?
 
Japanese (ex-french) 25mm would've also need some up-necking. As-is, the HE-T shell carried only 10g of explosives, while the HE shell had 14g. That is barely better than what the better 20mm shells had in the West, and worse than what the 23mm VYa had. The Soviet 275g 25mm AA shell carried 24 g of explosives.
Propellant weight for the Japanese 25mm was between 102 and 110g, shell weight of some 250 g had the MV of 900 m/s.
A 30mm HE shell of some 350g can allow for the greater HE content; even 25g is far better math than what the 25mm shell had. It will sacrifice some MV (the MK 103 did about 900 m/s with the 330g M-shell while using 112g propellant).
 
Shortround6 said:
You are our resident light AA expert.
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Shortround6 said:
How effective or easy to operate were the twin 30mm guns you worked on? Granted your targets were expected to much faster. Manual training and elevation? Sight system?
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It was hardest on the loaders, the almost 90 kg heavy magazines (each: when full with 50 rds; quad row) required some training to perfect. That was a 2-men job, though: stick the 1st one (closer to the aimer's post), then another,then retreat, either back in the vehicle or in the place of cover.
For the uninitiated, the ammo for the Czech 30mm was the most powerful of the 30mm cartridges used, and very heavy, a tad more than 1 kg each cartridge. The later Yugoslav/Serbian 30mm developments were centered around the less powerful Soviet 30mm cartridges.
There was both manual and electric training and elevation - some sort of mechanical help was indeed needed when the each gun at 270 kg was 100 kg heavier than a single US 37mm.

Optical sight was with 6 transparent plates with spiderwebs engraved (etched?), aimer was to pick the one commanded by the commander that was either just behind him on the gun (see here). or aside to the driver, when the intercom was used. The plates were to cater to the different speeds and distances of the target. If there was a radar coverage, commander was receiving the target data by them - as on can expect, that will be very clumsy against the saturation attack by modern aircraft. The 1st plate was for the targets of about 150 m/s speed (we've done all of training and shooting on the sleeve with that plate), 6th one for the fastest targets, while also featuring an additional spiderweb for slow targets, like helicopters, within the spiderweb for the fastest targets.
Target shooting, once per generation of gunners, was in the most cases successful after several months of training, but that training was not of high intensity in the 1st place.

There was a program to upgrade the 30mm systems with the same sight system from the Italian company Galileo, that featured the mechanical computer, same as used on the 20mm M55A4s but these were rare on the 30mm.

Back in the 1990s, neither of the light AAA systems was racking scores (although there was a number of kills, between the helicopters and MiG-29s), the MANPADS were better in scoring hits. The only AA gun that was able to automatically track the targets via electronic help was the Bofors 40mmL70, but these were few and far between.
The AA guns were mostly used against the ground targets, most notoriously against the helpless people trying to escape the Srebrenica cauldron.
 
Towed version with the SP version behind.

I have no idea if the towed version had powered assist or not.
Having a single man cranking on wheels seems like a job for very strong men
I have no idea what is in the box on the right side of the mount. Just tools or ammo or battery and motor?

Advantage for a WW II gun is that the planes are shorter and the aircraft weapons are shorter ranged,
WW II AIrcraft rockets were slow and short ranged so they had to get closer to the AA guns?
WW II AA gun can be a bit lower powered and so be smaller/lighter with easier control by man/men?
 
Shortround6 said:
Towed version with the SP version behind.
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The M53 (the towed, initial version) was tray-fed; note the sheet metal ammo holders. Genes of the different German 30 and 37mm are apparent, the M53 was probably little more than the MK 303 that people at Brno/Brunn continued with. The M53/59 adopted the box magazine ammo feed.

Shortround6 said:
I have no idea if the towed version had powered assist or not.
Having a single man cranking on wheels seems like a job for very strong men
I have no idea what is in the box on the right side of the mount. Just tools or ammo or battery and motor?
Click to expand...
The towed version was also probably with battery-powered electric motor? On the SP version, in that box were two 12V batteries, so it is not out of ordinary to expect that the towed version had these, too. Visits to the charging station for all the vehicles and guns was very frequent occurrence for us back then
(colleagues that operated the triple 20mm were pouring fuel for the small engine on their guns)
The gun was well balanced, though, but indeed manual operation was not something one wanted. The operators on the Strela 1 (SA-9 Gaskin) had it worst, there was no assisted turret operation on their system.
;
edit: the batteries on the towed version can be seen in the photos here; note that the cylindrical object next to the box is the spring-loaded counter-ballancer for the guns

The light AAA took numerous aircraft back in ww2, and crewmen were right to be concerned in every mission that involved bombing/strafing/rocketing at low altitudes. The bigger, slower and clunkier aircraft, the juicier target for the AA gunners. However, we can recall that the light AA guns were also claiming the very fast (V1) and nimble (fighter-bombers) provided that target information was good, that gunners were well trained, and that the guns were good and numerous.
USAF trying to use dive-bombing by the P-47s that started from as high as 20000 ft was probably the safest way around this problems, that still offered the reasonably high accuracy against the tactical targets? That is without considering the guided weapons, that came with their own set of problems.
 
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Thank you Tomo, that link shows several things, like the electric motors that powered the elevation and traverse?

It also illustrates the problems with trying to use larger guns or twin guns (and larger numbers) in hand worked mountings. Some users were complaining about slow traverse (mostly) in some of the 25mm and larger guns using hand cranks being able to track the attacking aircraft.

In many cases the adoption of multiple guns was to get around the low rates of fire and/or limited ammo capacity of the existing feed systems.
A twin Oerlikon can put out almost as many shells per second as a German quad 20mm and you have to reload two of the German guns to equal the number of rounds already in the Oelikons.
Japanese triple 25mm was an attempt to increase rate of fire but if it is too slow to track the targets you don't have much.
 
This was kinda why I was pontificating about the small & light 37-40mm guns.
The twin 30mm weighted like 3 US 37mm AA cannons (weights without the mounts), trying to hand-crank it often and in daily basis will require Arnie's muscles. Add two 90 kg magazines, and even Arnie might struggle
It might be possible with a single light 37mm gun, though.
 
For German AA guns (talking about troop defence) (especially 20mm) probably the first improvement would be to switch from small magazines to large drums with 60-90 shells and a direct hit (like British Polsten). The 4x20mm was made because only two barrels (alternately) fired because the small magazines had to be constantly changed. An AA 20mm system that uses the same number of crews as an 88mm AA is ... a bad way to use crews.
Having said that, the German AA was certainly effective, but it was overrun by a large number of Allied fighter bombers.
For national defence what they could (should) have developed faster is a system like Ezian. It does not need (missile) guidance, it is used as an AA grenade (with 500 kg of explosives). Both during the day and during the night. And it can use all equipment from 88 AA batteries - directors, radars ect. And don't use pilots like Me 163 . And even if the number of directly shot down planes is not large, disrupting boxes or night streams would be a major benefit.
 

Even before the war started the 20mm flak was considered marginal by the German brass. It was kept in production, and use expanded, due to expediency rather than any thinking it would be anywhere close to an 'optimal' point defense AA. If they hadn't been continually thinking they'll win the war in just a few more months, maybe they could have switched over to the more effective 37mm system sooner. (The quad 20mm weighted about as much as a single barrel 37mm flak 36, and more than the improved 37mm flak 43.)

Having said that, the German AA was certainly effective, but it was overrun by a large number of Allied fighter bombers.
Click to expand...

Yes. But it was also a major consumer of resources such as nickel, which would have been sorely needed elsewhere.


I'm not sure about that. Thanks to the tyranny of the square cube law, even with a really big boom you need to get fairly close to an enemy plane. Wikipedia mentions a lethal range for the Enziam 500kg warhead of about 45m. Compared to IIRC somewhere around 5-10m for the usual heavy AA shells. So you'd have to steer it manually from the ground within to 45m of a bomber. I'm just not seeing how that could be any kind of effective system. Guided missiles were the future of heavy AA, but getting all the pieces of the puzzle together for such a system to see service during WWII is probably too much to ask.
 
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