AA guns + rockets alternatives for 1935-45 (3 Viewers)

[Shortround6]

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?

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.

 

[tomo pauk]

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.

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?

 

[Shortround6]

Germans perhaps reckoned that, as far as the automatics go, their 37mm lacked the oomph with the 640g shell @ 820 m/s?

Step one. Hit the target.
Step two, Worry about the effectiveness.

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.

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.

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?

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

 

[tomo pauk]

Step one. Hit the target.
Step two, Worry about the effectiveness.

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.

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.

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.

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.

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.

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.

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

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

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.

 

[Shortround6]

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.

Most of these guns were good for 2000-3000meters for range. What they really needed was better sights/fire control

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.

see below

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.

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.

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.

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.

 

[tomo pauk]

Most of these guns were good for 2000-3000meters for range. What they really needed was better sights/fire control

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.

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.

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.

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.

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.