12cm AA Rocket with 0 effect

[el cid again]

The iron sights were to get the mounting on the target. This did not control the firing - which was based on an optical sensor. It is described in English in Naval Weapons of WWII I think.

[anarchyintheuk]

Thanks for the info T and John, et al. Not one of the IJN's better ideas if that weight of explosive is right . . . would have been better off w/ 25mms.

[el cid again]

I agree. The 25 mm - a rather old French design - was not that bad. Or they could have mass produced the captured Bofors 40 mm.
They DID - but took almost the entire war making trivial improvements first. Just do it monkey copy (like we thought they did everything)
and do it soon would be quite effective. Some 1945 mountings (singles and twins) look quite good.

[anarchyintheuk]

It may have smacked too much of the defensive to see priority but I haven't read anything concerning their 40mm program.

[el cid again]

You can find it in two places. First - in a naval ship reference on Japanese ships - look up the late war PC design - featuring the 40mm as main
battery. They finally got around to mass production of both guns and PCs - just in time for the economy to collapse! Second - look in
a naval weapons reference (e.g. Naval Weapons of The Second World War) - under IJN medium AAA. It is also mentioned sometimes in histories
of the Bofors. The Japanese really did improve the weapon system - but not enough to make any real difference in its effectiveness (at the most a %
or two). It was not worth the delay for design improvement - so say commentators.

[DuckofTindalos]

There was no mass production of the Bofors by the Japs, nor was it ever sent to sea. The post-war US tecnical mission to Japan studied some examples and found them poorly made, with low-quality machining and mismatched parts. It had problems with the ammunition feed as well.

The Japs took the British Army Bofors gun and and hand-cranked single mount captured at Singapore and spent three years trying to make it "better" by lengthening the tube (presumably to increase range) and adding a new flash suppressor.

It's slightly amusing, and must smack of very low prioritization, that the Japs took so long to copy a functioning Western design and broke it when they tried to improve it.

[inqistor]

Another report. Even earlier.

And another surprise. Only 12cm Rocket is described as "Extensively used". There is another model, HE, used for barrage, and described as used on "Shinzo" (I am guessing "Shinyo" Explosive Motor Boat). It have 1.63kg of explosives.
Surprise is... launcher. It is described as...
"Sextuple mounted on 2 wheels", yup, that actually make it... Japanese Nebelwerfer!


Of course, there should be 0.44lbs in my previous post, not 44, however, I have written "only", because this drawing shows 0.72 kg, as explosive. But even 0.22 kg is not small. Ho-301 had only 0.065, 40mm Bofors 0.068, while Japanese 10 cm/65 have 0.95.
Also, Rocket was modeled similar to San-Shiki, with shooting shrapnels into forward cone.

[DuckofTindalos]

[8|]

[inqistor]

Now, for data to be consistent with design:
effect is calculated simply from weight of projectile. Rocket weights 49.5, but it is complete shell+accelerator, so subtracting propellant we have EFFECT 42.

On the other side, it is less, than 10cm AA Gun, so should be weaker, that this gun, however it is specialized AA San-Shiki, so could be stronger.

Also, it is hard to calculte penetration. Maybe from comparison of bursting charge again.

Tests did not show much difference between 10 effect, 30 effect, and 14 penetration+30 effect. However, only in last case, those mountings with only 1 ammo actually shot, but it could be coincidence.

[el cid again]

A high velocity gun (doesn't matter much really - a long rifle fires more or less 900 m/sec - no matter it is a 6, 7 or 8 mm one in your hands,
a 75, 105, 155 mm in the field artillery - or a gigantic naval rifle or rail gun) - has much more penetration than a rocket does. Now if you
were to talk a truly long range rocket, coming in at mach 8, that would be different. The variable that would matter barely exists in the WWII
era - some kinds of rounds - e.g. the HEAT - would have exaggerated penetration (see, for example, the AT round for the 70 mm gun/howitzer
of the Japanese) - unlike most AT rounds of the period - and never mind the slow speed of the round (because it is a short tube) - the
penetration was respectable. For which reason AT rockets in our age - which still have the problem of low penetration due to low velocity
compared to a rifle shot - tend to use that solution. In sum, in AE, let penetration be a function of shell weight - based on ballistic data if you
have it - or on a same or almost identical shell if you do not. Does not matter much whose 8 inch shell you use - they are in the same ball
park for penetration - almost identical velocity and weight. Another factor for larger shells - AP penetration is better than HE - HE effect
is better than AP - and in RHS we went with the simple ration of HE shells had 2/3 the penetration of the same caliber AP shell did - while
effect became the square root of weight in pounds.

[Shark7]

ORIGINAL: Terminus

ORIGINAL: anarchyintheuk

ORIGINAL: inqistor


Well, with enough effect, they seem to work quite right. I am wondering if type of weapon makes any difference in combat algorithm (like rockets do not get penetration reduced etc.).

Now, considering weight of this Rocket, it seems, that 30 effect will be closer to truth.
Also, I do not understand why they have only 1 ammo point. They were light enough to get few hundred on-board, and few guys could rearm whole panel, probably under minute.

Does anyone have a picture of one of these launchers? If it's one of those 28-barrel launchers, I'd imagine it was difficult to hand reload and hand fuse 28 rockets. How far was the ammunition hoist from the firing system? Iirc the crews had to wear special gear and take cover while it was firing.

It would be interesting to know how many reloads were carried.

The launcher was adapted from the triple 25mm mount, and consisted of a box with four rows of seven rockets. Pretty simple and pretty useless.

Not much unlike the 25mm guns they replaced on the mounts... [:'(]

[el cid again]

25 mm were not useless.

In 1982, RN scoured the world to buy any form of 20 mm they could find.

They STILL matter re low fliers.

Granted - when the 20s open up - it is too late to prevent ordnance from hitting the ship.
So they are "revenge weapons." But they DO mess up the aimer - ANY AAA fire reduces
accuracy in fact IRL - typically cutting hit probability by half or so. Some simulaitons model
this - for all weapons.

[inqistor]

ORIGINAL: el cid again
A high velocity gun (doesn't matter much really - a long rifle fires more or less 900 m/sec - no matter it is a 6, 7 or 8 mm one in your hands,
a 75, 105, 155 mm in the field artillery - or a gigantic naval rifle or rail gun) - has much more penetration than a rocket does. Now if you
were to talk a truly long range rocket, coming in at mach 8, that would be different.

Penetration is calculated from simple formula, taking into consideration speed (most important), weight of projectile, and its diameter. I think I have it in one of my books. Small calibers are too light, to have any impact on standard armor (they need like MACH 3). But that is for simple physical penetration.

The variable that would matter barely exists in the WWII era -

But this is the whole reason, why Germany kick a** to this day (anyone wonders, who produces guns for Abrams?)! With longer gun, and greater bursting charge, you get greater speed, and penetration. That is why Panther Gun, despite also being 75mm (like PzIV, T-34 (almost), or Sherman), had even better shorter range penetration, that 88mm of Tiger I.

some kinds of rounds - e.g. the HEAT - would have exaggerated penetration (see, for example, the AT round for the 70 mm gun/howitzer
of the Japanese) - unlike most AT rounds of the period - and never mind the slow speed of the round (because it is a short tube) - the
penetration was respectable.

Now HEAT is based purely on explosive material. Speed (and range) have nothing to do with it (except for hit probability). No matter the range, shaped-charge explosion gives better penetration, that rocket speed. And it is PURELY by explosive material.

In sum, in AE, let penetration be a function of shell weight - based on ballistic data if you
have it - or on a same or almost identical shell if you do not. Does not matter much whose 8 inch shell you use - they are in the same ball
park for penetration - almost identical velocity and weight. Another factor for larger shells - AP penetration is better than HE - HE effect
is better than AP - and in RHS we went with the simple ration of HE shells had 2/3 the penetration of the same caliber AP shell did - while
effect became the square root of weight in pounds.

Well, problem is, that most guns could use BOTH AP, and HE. If they used AP, against armored ship, effect should be lower, but against unarmored merchant, they could use HE, and make greater damage. I do not think, simulation of this is possible in AE.

Now, the main problem with AA Rocket is:
Does penetration is accounted, in any way, during hitting airplane? No matter of the value, I doubt it will be more, than even smallest armor for ship. And this actually assumes, that Rocket will somehow fire against enemy ship (it have, like, 2 range).

Interesting enough, if number 0.73kg of explosive material is true, it is actually identical to TYPE 99 MINE, so penetration could be similar.

In 1982, RN scoured the world to buy any form of 20 mm they could find.

Was not this because of research for other, internal PHALANX version?

[dwg]

ORIGINAL: inqistor

In 1982, RN scoured the world to buy any form of 20 mm they could find.

Was not this because of research for other, internal PHALANX version?

During the Falklands war a considerable amount of light AA, often 7.62mm GPMGs, was strapped on to both the warships and STUFT troopships, with even small arms being used in Bomb Alley -- ISTR a mention of the NAAFI manager from one of the frigates firing a 9mm Sterling SMG from atop the helicopter hangar. After the end of hostilities many of the existing 20mm mounts were replaced with a mix of Oerlikon 20mm KAA and 30mm KCB, there were also plans for extensive fitting of 30mm Goalkeeper CIWS, but that only really happened on the Invincibles in the end.

[dwg]

ORIGINAL: Terminus

There was no mass production of the Bofors by the Japs, nor was it ever sent to sea. The post-war US tecnical mission to Japan studied some examples and found them poorly made, with low-quality machining and mismatched parts. It had problems with the ammunition feed as well.

Not to disagree with any of this, but wasn't that also true of the Swedish original? ISTR reading somewhere that when the US licensed the design they found a lot of 'file to fit' markings on the plans. Given the way Japanese industry was set up at the time, mismatched parts filed to fit might actually have suited their working practises better.

[Sardaukar]

ORIGINAL: dwg

ORIGINAL: inqistor

In 1982, RN scoured the world to buy any form of 20 mm they could find.

Was not this because of research for other, internal PHALANX version?

During the Falklands war a considerable amount of light AA, often 7.62mm GPMGs, was strapped on to both the warships and STUFT troopships, with even small arms being used in Bomb Alley -- ISTR a mention of the NAAFI manager from one of the frigates firing a 9mm Sterling SMG from atop the helicopter hangar. After the end of hostilities many of the existing 20mm mounts were replaced with a mix of Oerlikon 20mm KAA and 30mm KCB, there were also plans for extensive fitting of 30mm Goalkeeper CIWS, but that only really happened on the Invincibles in the end.

http://www.hmsardent.org.uk/page29/page29.html

The ship had lost its SeaCat launcher and the hanger roof had been ripped open like a sardine can. The flight deck was in flames, as was most of the back end of the ship. All computer weapon systems were off-line leaving only the close range guns to defend against further attacks ourselves with. The crew of Ardent now relied on people like the ships NAAFI canteen manger, John Leake, who had been made a Petty Officer when active service was declared. John had used a GPMG when he was in the Army and had volunteered to man the weapon again, when he was put in uniform. He was now alongside the weapons teams working under the direction of the visual weapons director. John's action throughout the Argentine attacks was inspiring to all the weapons crews. His award of the Distinguished Service Medal after the conflict was a credit to his bravery; and the confirmed "kill" of an Argentine Skyhawk forced to land at Port Stanley airport after its fuel tanks were hit by John's GPMG small arms fire.

[dwg]

ORIGINAL: Sardaukar

http://www.hmsardent.org.uk/page29/page29.html

The ship had lost its SeaCat launcher and the hanger roof had been ripped open like a sardine can. The flight deck was in flames, as was most of the back end of the ship. All computer weapon systems were off-line leaving only the close range guns to defend against further attacks ourselves with. The crew of Ardent now relied on people like the ships NAAFI canteen manger, John Leake, who had been made a Petty Officer when active service was declared. John had used a GPMG when he was in the Army and had volunteered to man the weapon again, when he was put in uniform. He was now alongside the weapons teams working under the direction of the visual weapons director. John's action throughout the Argentine attacks was inspiring to all the weapons crews. His award of the Distinguished Service Medal after the conflict was a credit to his bravery; and the confirmed "kill" of an Argentine Skyhawk forced to land at Port Stanley airport after its fuel tanks were hit by John's GPMG small arms fire.

And from further down on that page: "in a desperate bid to defend the ship, members of the ship’s flight were killed engaging the aircraft with small-arms fire"

Looks like I ran the two incidents together.

[Sardaukar]

ORIGINAL: dwg

ORIGINAL: Sardaukar

http://www.hmsardent.org.uk/page29/page29.html

The ship had lost its SeaCat launcher and the hanger roof had been ripped open like a sardine can. The flight deck was in flames, as was most of the back end of the ship. All computer weapon systems were off-line leaving only the close range guns to defend against further attacks ourselves with. The crew of Ardent now relied on people like the ships NAAFI canteen manger, John Leake, who had been made a Petty Officer when active service was declared. John had used a GPMG when he was in the Army and had volunteered to man the weapon again, when he was put in uniform. He was now alongside the weapons teams working under the direction of the visual weapons director. John's action throughout the Argentine attacks was inspiring to all the weapons crews. His award of the Distinguished Service Medal after the conflict was a credit to his bravery; and the confirmed "kill" of an Argentine Skyhawk forced to land at Port Stanley airport after its fuel tanks were hit by John's GPMG small arms fire.

And from further down on that page: "in a desperate bid to defend the ship, members of the ship’s flight were killed engaging the aircraft with small-arms fire"

Looks like I ran the two incidents together.

Some pretty amazing things happened on that ship that time and Leake was definitely not only one firing different weapons towards enemy planes, he is just best-known.