AA guns + rockets alternatives for 1935-45

[SplitRz]

Z Battery 'non rotating projectiles' did go on to form the chassis of post war AC sports cars. Just as Morrison shelters became Cooper racing car chassis with brake drums made of surplus ship engine cylinder liners. Good steel was at a premium in post war Britain. Hence Land Rovers came with aluminium bodywork not steel. But I digress from the OP.

Didn't the Z battery projectiles also form the basis for the later aircraft mounted 25 and 60lb PRs that were so instrumental later against submarines, shipping and for ground attack?

[edit!] Yes! it seems they did. So very much not entirely wasted - Z-battery - RP-3

Sadly, Z Battery operation possibly killed more British civilians than German aircrew. A Z Battery was infamous for being the cause of this horrific disaster: The Bethnal Green Tube Disaster

 

[SplitRz]

British gave up fairly quickly on AA rockets and for an army that hung onto the Smith gun, the Northover projector and the Blacker bombard that may tell us something.

The Smith Gun, Northover projector and Blacker Bombard were IIRC only ever issued to The Home Guard, and never actually deployed in action, let alone with the regular army (except possibly for some early war exercises).

The main impetus behind these rocket (and/or black powder propelled) weapons was to get something/anything into production at a time when invasion looked like a real threat. By the time that has passed by '41, all the best weaponry was clearly going to be needed in theatres like North Africa and beyond. So all the Heath Robinson stuff stayed at home for the Old Boys to exercise and drill with.

I believe that the Northover projector was actually credited with a kill when fired from a trawler and managed to knock down an HE111! Joking aside, given it used next to no resources of any significance and the ships own steam lines for its propellant, I think it was a rather cunning invention. More recently, I wondered if they shouldn't have dusted off something similar as an anti-pirate weapon firing internationally 'plausibly deniable' ammo like bowling balls at the Go-Fasts off the Horn of Africa!

 

[Shortround6]

The Smith Gun, Northover projector and Blacker Bombard were IIRC only ever issued to The Home Guard, and never actually deployed in action, let alone with the regular army (except possibly for some early war exercises).

Turns out they gave rockets to the Home Guard

There was a single launcher with around 1000 made by Sept 1940
Most went to Merchant Navy.

 

[yulzari]

The Smith Gun, Northover projector and Blacker Bombard were IIRC only ever issued to The Home Guard, and never actually deployed in action, let alone with the regular army (except possibly for some early war exercises).

The main impetus behind these rocket (and/or black powder propelled) weapons was to get something/anything into production at a time when invasion looked like a real threat. By the time that has passed by '41, all the best weaponry was clearly going to be needed in theatres like North Africa and beyond. So all the Heath Robinson stuff stayed at home for the Old Boys to exercise and drill with.

I believe that the Northover projector was actually credited with a kill when fired from a trawler and managed to knock down an HE111! Joking aside, given it used next to no resources of any significance and the ships own steam lines for its propellant, I think it was a rather cunning invention. More recently, I wondered if they shouldn't have dusted off something similar as an anti-pirate weapon firing internationally 'plausibly deniable' ammo like bowling balls at the Go-Fasts off the Horn of Africa!

The Blacker Bombard was not just for the Home Guard but was issued to the Regular army and served in action in North Africa. Post Dunkirk it was also issued to Regular infantry in Britain until they could make enough anti tank guns for them.

It was the foundation of the very successful naval Hedgehog spigot mortar which allows ASW vessels to fire forwards when approaching an asdic contact. Equally the proven spigot mortar Bombard was a model for the later PIAT infantry man portable anti tank weapon.

One finds Blacker Bombard Home Guard weapon pits filled in post war all over Britain, especially in the south and east. Built to a standard pattern in concrete with a central weapon pin swivel post and protected reload. In a suitable position they can dominate any target within their range which would be exceeding displeased with receiving a substantial HE round landing on them. Ideally placed where they can be covered by small arms fire to keep enemy infantry at a distance. Especially used in suburban situations with the petrol fougasse being more popular in rural areas. My grandfather's village had a large Canadian Pipe Mine/s in the road behind the village. Stayed there until the war was over. Always fun as laid full of an explosive liable to deterioration that sometimes needed to be emptied when found unstable and refilled. Still occasionally found when digging works and some are still full of that potentially unstable explosive. Another occasional find is a group of rusted out oil drums in the undergrowth by a dip in the road which were filled with petrol and a throwing/igniting charge to toss them flaming into a movement restricted area like a sunken road and ruin an enemy's day and do no good at all to any transport.

https://zeticauxo.com/wp-content/uploads/2023/02/pipe-mines.pdf

Thousands of These Mortars Dotted the British Countryside For An Invasion That Never Came

Worst. Mortar. Ever.

www.historynet.com

Hedgehog (weapon) - Wikipedia

en.wikipedia.org

View: https://www.youtube.com/watch?v=uk_vS-VdYas&t=117s

Flame fougasse - Wikipedia

en.wikipedia.org

 

[SplitRz]

Another occasional find is a group of rusted out oil drums in the undergrowth by a dip in the road which were filled with petrol and a throwing/igniting charge to toss them flaming into a movement restricted area like a sunken road and ruin an enemy's day and do no good at all to any transport.

Ah, the infamous Flame Fougasse! Weirdly, one thing we were never short of in wartime were petrol reserves.

Another still fairly regular find in attics and old sheds are stores of Northover Projector / improvised grenade 'incendiary projectiles' - basically a stoppered bottle of petrol containing a lump of phosphorous. Something to be dropped onto a hard surface or uncorked out of curiosity at your peril!

 

[peceed]

In the case of Poland, the most obvious alternative is to improve decision-making and introduce more 40 mm Bofors guns into production earlier. Additionally, the Polsten gun should have been introduced before the war.

As for heavy anti-aircraft artillery, the 75 mm gun should have been abandoned and a 105 mm heavy gun should have been created instead, which could provide better protection against high-altitude bombing of cities. Practice has shown that medium-caliber artillery is completely sufficient for front-line units, which makes the mobility of heavier artillery irrelevant.

A 10.5cm shell held 1.5kg of explosive and about 5.6kg of propellent but used a crap load of steel. That 500kg charge in the rocket is 333time more expensive in explosive.

They had different mechanisms of damage. The blast damage scales very poorly with distance compared to fragments.
If I had to improve something in this warhead, i would experiment with fuel-air explosion, using coal dust.
Even if the resulting explosion was not stronger, it would be many times cheaper.

Germans were using obscene amounts of war material just to kill one bomber, or to damage a few.

This reasoning has wrong assumptions - that the primary purpose of AA artillery was to destroy aircraft. In fact, the primary purpose of artillery was to reduce the effectiveness of air raids by frightening crews and raising the altitude of bombing.
This is the main strategic strategic goal in worsening the enemy's cost-to-effect ratio. Increasing aircraft losses is a secondary effect and requires disproportionate resources to the primary effect - in this respect, fighters work better.

The Germans would have been helped the most by a proximity fuse, but in the absence of one I once developed alternative concepts for increasing the effectiveness of AA artillery.
It is known that at some point the use of impact fuses instead of time fuses increased the effectiveness of German artillery by a factor of 3x. In that case, however, the shells were too large, giving a huge overkill. So I decided to create cluster ammunition with impact sub-shells, separated by a time fuse. The simplest solution seems to be standard tubes with a diameter of about 4 cm, creating bundles composed of 3, 4 and 7 elements for shells of calibres 88, 105 and 128 mm, weighing 2.5 kg and containing 400 grams of hexogen (guaranteeing the downing of the aircraft).
Another, even more hardcore solution is to recover shells that have not hit using bright parachutes (a mechanism designed in such a way that opening the parachute requires unscrewing the fuse.
The final idea is to create a 5 cm smoothbore gun that would fire aerodynamically stabilized shells at very high speed using very long barrels (~1300 m/s). Such a gun would fill the gap between 37 mm and 88 mm guns.

 

[tomo pauk]

Some self-propelled options:
- twin 20mm or one 25mm or one 30mm on the Wespe base (obviously, without that tall superstructure)
- 4x 20mm, 2x 30mm or 1x 37mm on the StuG-III base
- twin 20mm on a truck for basically any country
- Soviets actually producing the light tank with the twin HMG for AA work
- one 25mm or twin 20mm on the Lorraine 37 tractor

A good 75mm AA gun on the truck or on another vehicle (half-track or a fully-tracked vehicle) would've probably also came in handy, and easier to do than with the 85mm and bigger guns. Also useful for anti-tank work, as well as, need-be, 'normal' artillery piece.

Probably the best of that lot were the Hungarian Nimrod, as well as the British Crusader AA tank, both with 40mm Bofors as the business end.

 

[z42]

In the case of Poland, the most obvious alternative is to improve decision-making and introduce more 40 mm Bofors guns into production earlier. Additionally, the Polsten gun should have been introduced before the war.

As for heavy anti-aircraft artillery, the 75 mm gun should have been abandoned and a 105 mm heavy gun should have been created instead, which could provide better protection against high-altitude bombing of cities.

Were the LW bombers flying above the ceiling of 75mm AA guns early in the war?

Practice has shown that medium-caliber artillery is completely sufficient for front-line units, which makes the mobility of heavier artillery irrelevant.

Many armies fielded heavy AA guns somewhere in the range of 90mm, which seem to have been about the largest size gun that was still decently road mobile. Or do you mean medium caliber as something like the 40mm?

If I had to improve something in this warhead, i would experiment with fuel-air explosion, using coal dust.
Even if the resulting explosion was not stronger, it would be many times cheaper.

Hmm, I'm not sure a fuel-air explosion works for AA. Getting the fuel to mix properly with air when the bursting charge of the supersonic rocket/shell cracks it open sounds like a non-trivial problem.

But for a somewhat less ambitious attempt, they could have increased the ammonium nitrate content in their amatol mixture? Even at a 80/20 AN/TNT mixture it has about 2/3 the power of pure TNT, and a lot cheaper.

The final idea is to create a 5 cm smoothbore gun that would fire aerodynamically stabilized shells at very high speed using very long barrels (~1300 m/s). Such a gun would fill the gap between 37 mm and 88 mm guns.

As I pointed out back on page 1 of this thread, they had something like this in prototype stage. A 88mm smoothbore gun firing fin stabilized saboted shells (about 50-60mm diameter?) at high velocity and equipped with an impact fuse. This was not so much filling the gap between 37 and 88mm, as something envisioned to be a better heavy AA providing improved kill probability against Allied heavy bombers.

 

[peceed]

Many armies fielded heavy AA guns somewhere in the range of 90mm, which seem to have been about the largest size gun that was still decently road mobile.

That's right, which answers your previous question - the 75 mm caliber was considered too weak even before the war.
The Germans bombed from an altitude of over 8 km, which would have left practically no room for horizontal fire maneuvers. Ju-86P with an altitude of 12 km were in preparation. That's why I propose to skip the 90 mm caliber. An additional advantage is the fact that the 105 mm can share the production of ammunition with 105 mm field guns.
And finally - large shells with a time fuse are more economical, because the density of fragments counts, so the area affected by the explosion scales as the mass of the shell raised to the power of 3/2. In the case of proximity fuses, this no longer matters and their effectiveness (basically the area perpendicular to the direction of the shell's flight) is proportional to the mass.

Hmm, I'm not sure a fuel-air explosion works for AA. Getting the fuel to mix properly with air when the bursting charge of the supersonic rocket/shell cracks it open sounds like a non-trivial problem.

The velocity of the fragments after the explosion is much higher and can be directed sideways, which can positively use the speed of the projectile. But this is uncharted territory - blast warheads scale their effect poorly with distance and have lost their effectiveness abruptly against structurally stronger supersonic aircraft.

This was not so much filling the gap between 37 and 88mm, as something envisioned to be a better heavy AA providing improved kill probability against Allied heavy bombers

As I pointed out back on page 1 of this thread, they had something like this in prototype stage. A 88mm smoothbore gun firing fin stabilized saboted shells (about 50-60mm diameter?) at high velocity and equipped with an impact fuse.

I do not like sabots for AA - just make longer barrels!

This was not so much filling the gap between 37 and 88mm, as something envisioned to be a better heavy AA providing improved kill probability against Allied heavy bombers.

My idea was to make a cost efficient gap filler.
In order to increase hit probability from 88 mm guns i have cluster loads

 

[Shortround6]

The Germans bombed from an altitude of over 8 km, which would have left practically no room for horizontal fire maneuvers. Ju-86P with an altitude of 12 km were in preparation. That's why I propose to skip the 90 mm caliber.

Could bomb from 8km is a lot different than did bomb at 8km. Most B-17s did NOT bomb at 8km. Most He 111s didn't fly at 8km until the bombs were gone and around 1/2 the fuel was used up. Do 17z had service ceiling of about 7000 meters at normal max load. Bombers could not fly at service ceiling altitude and say in formation. TO stay in information planes had to fly 1-2km lower than their service ceilings.

An additional advantage is the fact that the 105 mm can share the production of ammunition with 105 mm field guns.

The two can share some production facilities, tooling.
You don't really want to share actual projectiles between 105mm Field guns (howitzers) and AA guns. The US 105 Howitzer used just over 3lbs of propellent, the US 105mm AA gun (not many made) used over 10.5lbs of propellent. The Howitzer shells used over 1/3 more HE content even though the shells were similar in weight.
A lot may depend on the types of steel you can use in the shell bodies and the heat treatment. Firing thin wall shells at high velocity sometimes doesn't end well (shell bursts in the gun tube).

 

[ThomasP]

re

In order to increase hit probability from 88 mm guns i have cluster loads

The main problem with using an 88mm cluster load is that you would only be able to have 2(?) sub-munitions of usable size. A second problem is that the round will be lighter (both in mass and in structure), resulting in lower muzzle velocity and/or greater loss in velocity at range.

A third problem is cost - ie what would be the monetary cost in terms of personnel and materiel, and the logistics costs of man hours and supply/number or rounds required, of the AA cluster round vs a conventional AA round vs the % chance of a hit.

Rockets, on the other hand, lend themselves to cluster munitions. The Germans looked at AA rockets with cluster munitions during the war, though I do not think any made it past the advanced design stage?

"What if the Germans had radar proximity fused AA shells?"

 

[peceed]

The main problem with using an 88mm cluster load is that you would only be able to have 2(?) sub-munitions of usable size.

How? The most obvious solution is to have 3 sub-shells in the common "sabot"!

A second problem is that the round will be lighter (both in mass and in structure)

After thinking it over, I decided that the best solution would be a segmented design similar to that used in the SALVO program.
In this way, you can easily get 3 sub-shells, and with a lot of effort - maybe even 4 for the 85 mm caliber.A very interesting case would be the 128 mm shell, which can get up to 14 sub-shells.

A third problem is cost - ie what would be the monetary cost in terms of personnel and materiel, and the logistics costs of man hours and supply/number or rounds required, of the AA cluster round vs a conventional AA round vs the % chance of a hit.

Each sub-shell could cost as much as an entire classic 88mm shell with an impact fuse and still be a worthwhile upgrade. Additionally, we do not have to worry about shell fragmentation, so we can optimize it solely for pure strength. I see only one real challenge - creating sufficiently reliable and safe fuses.

Finally, an interesting fact - 128 mm shells are much more effective with a time fuse than with an impact fuse due to their size, so the increase in effectiveness with cluster shells would only be roughly 3 times (for 14 sub-shells). Therefore, 128 mm shells would benefit more from a proximity fuse with an appropriate range: first of all, they have a lot of space for electronics, the lowest accelerations when firing, and provide the best damage to fuse cost ratio (provided that one with the appropriate sensitivity can be created).

The Germans considered that about 400 grams of PETN are needed to be sure of shooting down the plane regardless of the place of impact.It would be good to know what the statistics were. Because if, for example, 200 grams gave 50%, then it is worth using twice the number of smaller sub-projectiles, which in addition to the same number of shoot-downs would add the same number of severely damaged.

Rockets, on the other hand, lend themselves to cluster munitions.

And reusability. A reusable Taifun with a parachute that only needs to be refueled before the next use could reduce the cost of air defense by a factor of at least 5x - assuming free collection of missiles by civilians.

With the cost of firing a missile reduced from 25 to 5 RM, even the need to fire 16 thousand missiles to shoot down a bomber would guarantee a sensational cost ratio: 80k RM for destroying an aircraft costing 300k dollars (about 750k RM).

 

[z42]

Some self-propelled options:
- twin 20mm or one 25mm or one 30mm on the Wespe base (obviously, without that tall superstructure)
- 4x 20mm, 2x 30mm or 1x 37mm on the StuG-III base
- twin 20mm on a truck for basically any country
- Soviets actually producing the light tank with the twin HMG for AA work
- one 25mm or twin 20mm on the Lorraine 37 tractor

A good 75mm AA gun on the truck or on another vehicle (half-track or a fully-tracked vehicle) would've probably also came in handy, and easier to do than with the 85mm and bigger guns. Also useful for anti-tank work, as well as, need-be, 'normal' artillery piece.

Probably the best of that lot were the Hungarian Nimrod, as well as the British Crusader AA tank, both with 40mm Bofors as the business end.

Per this video from MHV Germany was apparently planning to start mass manufacturing a SP AA vehicle mounting something like the Kugelblitz turret with two 30mm Mk 103 on a Pz 38 / Hetzer chassis starting in spring 1945. Reason was that apparently production of Pz IV chassis was scheduled to stop around that timeframe, but Pz 38 production was still to continue.

No idea how that was planned to work, it was apparently already difficult to fit the Kugelblitz turret on the Pz IV chassis, and the Pz 38 chassis is a lot smaller still. Perhaps it was some kind of reduced size variant of the Kugelblitz turret?


View: https://www.youtube.com/watch?v=HGEXluz5nFA&t=705s

 

[tomo pauk]

No idea how that was planned to work, it was apparently already difficult to fit the Kugelblitz turret on the Pz IV chassis, and the Pz 38 chassis is a lot smaller still. Perhaps it was some kind of reduced size variant of the Kugelblitz turret?

The Hetzer was 50cm wider than that of the Pz-38(t)and it was also considerably heavier.
Possibly the separate radioman will not be on this combo vehicle? Note also that the Hetzer gained some sort of sponsons, that might allow for the more comfortable turret installation than the Pz-38(t).
Armor of the Kugelblitz turret was not that thick, meaning that turret was light.

 

[SplitRz]

This reasoning has wrong assumptions - that the primary purpose of AA artillery was to destroy aircraft. In fact, the primary purpose of artillery was to reduce the effectiveness of air raids by frightening crews and raising the altitude of bombing.
This is the main strategic strategic goal in worsening the enemy's cost-to-effect ratio. Increasing aircraft losses is a secondary effect and requires disproportionate resources to the primary effect - in this respect, fighters work better.

Indeed, interesting! However, to achieve the primary objective, there has to be a provable, viable threat - and that means aircrew *knowing* that a squadron mate has not come back, or has experienced having their own aircraft hit by flak. And that means matching improvements in aircraft performance with improved accuracy, destructive power, and range in the artillery firing at them.

So its an interesting trade-off and I'm not convinced it was factored into its 'primary purpose' at a design and development or strategic deployment level, was it? Surely gun makers designed guns and sighting systems with the prime intent of hitting and destroying aircraft and were funded to do their utmost to achieve that, and Flak generals and civic leaders sited AA, radars and searchlight batteries not to indirectly reduce effectiveness or raising altitude (though it undeniably had that impact where and when it was effective) - but specifically to attrite enemy bombers.

I'm reminded of countless stories from WW1 where a lot of pilots pretty much ignored the AA (or 'Archie' as they called it): A bit of gentle weaving and a change in altitude was enough to throw off the simple sighting and low velocity rounds coming up at them from slow firing artillery pieces. It was the machine guns and mass rifle fire at low level that they feared, unless they were attacking an observation balloon. AA that can be treated with contempt because it is not a mortal threat, will not do much to hurt morale or effectiveness.

If it wasn't true, surely the British would have soldiered on with the Z batteries and developed them further, and the Germans would actually have developed things like 'scarecrow flak rounds' which would have been real pyrotechnics and not a myth covering up a grim reality?

One undeniable, overlooked and tbh, rather unsung contributor which had the express intention of 'reducing the effectiveness of air raids by frightening crews and raising the altitude of bombing' was the humble barrage balloon. That seemed like a very cost effective form of air defence / enhancement against low level attacks and was also useful against V1s. (In fact, in the age of low level cruise missiles and drones and carbon-fibre cables, I wonder if they're an idea that might usefully be dusted off. )


[edit] - This article from 1989 is a bit Barrage balloons - then and now?long in the tooth, but makes for interesting reading IMO -