Machine Guns and Cannons (Ground, Vehicle, and Aircraft Mounted Weapons)

[dy031101]

I'd think that the Japanese could have come up with and/or mass-produced only so many newly-developed ordnances, considering all the resources that went to naval use.  Asking for more and they would have to improvise.

[jcf]

Wikipedia claims that the Ki-45Kai Otsu is armed with a manually-loaded 37mm gun.

Interesting...... I wonder how the installation looks like and how the crew is supposed to load it......

Does anyone have illustration on how the whole thing worked?

Type 98 37mm (IJA license copy of French 37mm  gun according to Francillon) mounted in the ventral tunnel.
In other words mounted in the belly and accessible from the cockpit.



If indeed it was the license built French gun, then it would be the Type 11 Infantry Gun, however, the Type 94 AT makes more sense than the Type 11.

http://en.wikipedia.org/wiki/Type_11_37_mm_Infantry_Gun

http://en.wikipedia.org/wiki/Type_94_37_mm_Anti-Tank_Gun

[dy031101]

According to this...



... the Type 94 is utilized.

I wonder how the Type 1 47mm would have worked...... it's reputed to be light for its class.

[rickshaw]

Just had a look through my library and found this:

"The early 37mm Type 98, a version of the Type 94 tank gun used the same 37x132R ammunition, was manually loaded...."

p 174, Rapid Fire The Development of Automatic Cannon, Heavy Machine Guns and their Ammunition for Armies, Navies and Air Forces.  A.G. Williams.

According to The Boys and Girls Own Book of World Knowledge:

The Type 94 37-mm AT gun was introduced in 1936. The design originated as an improvement to the Type 11 37 mm Infantry Gun, which was also used as a primitive anti-tank weapon...

The Type 94 37 mm AT gun was based on a German (Rheinmetal-Borsig) quick fire design, the 3.7 cm PaK 36...

The Army claimed a penetration capability of 20 mm of armor  at a distance of 1000 meters, and penetration of up to 40 mm at shorter distances. However, it appears unlikely that this performance was achieved in actual combat, as the Army Technical Bureau continued to experiment with ways to increase muzzle velocity through 1941.

Rate of fire    30 rpm
Muzzle velocity    700 m/s (2,300 ft/s)

[Maverick]

Seems odd that they chose a manually loaded weapon.  Single shot is entirely fair enough for the calibre (although there were automatic weapons of the same size) but clip loaded surely.  Definitely a Japanese way of doing things.

Wikipedia wasn't very forthcoming on how long the version stayed in service before being replaced (especially given that it was developed to counter B-17s) and the only things I currently have access to are Japanese e-books that don't shed light on the subject (in English that is).

One would have to think that with a cyclic rate (if you could call it that!) of 2! rounds per minute, it wouldn't have been to well received by the IJAAF.

Regards,

Mav

[icchan]

Idle thoughts.  Say you have a navy that's still tugging around old early-mid-WWII-era destroyers and such, and you'd like to get them on a little better modern footing (ca. Vietnam).  How hard would it be to swap out the 40mm Bofors cannons that were everywhere, and start putting in Oerlikon 35s, possibly even in a Gepard turret mount?  I'd heard somewhere it was considered once, but I'm thinking more for modernizing old ships.  Considering the timeframe, CIWS is a little ways off yet and pretty advanced, so the R2D2 is not available.

Missile defense should be considered.  How well would a suitable ship-based radar system work if it could feed fine target data to the gun turret, which would have operators inside to make sure the guns feed happily and to pull triggers/fine-adjust the controls?  I can see something like the operator having a gunsight like a contemporary fighter HUD, with the computer in the ship calculating angles and lead and such.

Considering the era, a countermissile system like RAM is flat-out unavailable, and these destroyers aren't going to be very big and it's supposed to be a relatively inexpensive upgrade, so even a one-armed bandit and its magazine is kind of out of the question.

[Weaver]

Idle thoughts.  Say you have a navy that's still tugging around old early-mid-WWII-era destroyers and such, and you'd like to get them on a little better modern footing (ca. Vietnam).  How hard would it be to swap out the 40mm Bofors cannons that were everywhere, and start putting in Oerlikon 35s, possibly even in a Gepard turret mount?  I'd heard somewhere it was considered once, but I'm thinking more for modernizing old ships.  Considering the timeframe, CIWS is a little ways off yet and pretty advanced, so the R2D2 is not available.

Entirely possible: there were two different twin Oerlikon 35mm mountings produced:

A) Oerlikon Type GDM-A. This is basically the same as their land-based twin mount, but in a weatherproof GRP turret. The guns are clip-fed KDCs so on-mount crew are needed, but the gun can have RPC for remote aiming by whatever FCC you fancy.

B) Oerlikon/OTO-Melara Type GDM-C. This may be the one you're thinking of. It uses two belt-fed KDA cannons in side pods on a box-shaped turret, the whole thing looking like a simplified Gepard turret with no on-mount radar. It can still have an on-mount layer, but the whole thing is much more oriented towards remote control. Apparently, the USN seriously considered this gun as an option for the FFG-7s before plumping for the 76/62 compact mount instead.

You might also consider 30mm weapons: there's an Oerlikon twin belt-fed mount with an enclosed or open cabin to one side (built under licence in the UK by BMARC and seen on various post-Falklands RN ships), and there's also the US Emerlec mounting, which has a manned cabin with podded guns to either side.

Missile defense should be considered.  How well would a suitable ship-based radar system work if it could feed fine target data to the gun turret, which would have operators inside to make sure the guns feed happily and to pull triggers/fine-adjust the controls?  I can see something like the operator having a gunsight like a contemporary fighter HUD, with the computer in the ship calculating angles and lead and such.

The problem is computing power. You need a fast radar scan rate which reduces the detection range, giving you less than two minutes to detect the threat, evaluate it and react to it. You then have to slew the trackers and/or guns onto target, acquire the target, engage it, evaluate the results and re-engage if neccessary. 1960s radars wern't brilliant at tracking targets at low elevations, so you want optical backup, but frankly, that's better done by a co-axial TV camera on the target tracking radar operated by the same guy who's running the whole engagement from the nice warm CIC anyway, than by a frozen, bored gunner on the mounting who's got to be told when to take over.

[kitnut617]

Seems odd that they chose a manually loaded weapon.  Single shot is entirely fair enough for the calibre (although there were automatic weapons of the same size) but clip loaded surely.  Definitely a Japanese way of doing things.
Mav

I believe that the 75mm mounted in the B-25 was also one-shot and manually loaded ---

[icchan]

B) Oerlikon/OTO-Melara Type GDM-C. This may be the one you're thinking of. It uses two belt-fed KDA cannons in side pods on a box-shaped turret, the whole thing looking like a simplified Gepard turret with no on-mount radar. It can still have an on-mount layer, but the whole thing is much more oriented towards remote control. Apparently, the USN seriously considered this gun as an option for the FFG-7s before plumping for the 76/62 compact mount instead.

Didn't know that about the USN, though I think they're better served with the 76mm.  Me, I definitely want the dedicated rapid-fire AA capability, rather than the more multirole thing. As far as the GDM-C goes, I think that's the one - found a pic here of the thing on the stern of a Libyan corvette.  Frankly that's about spot-on, I think, now the big question is whether or not it'd fit in the gun tubs of a Fletcher-class.  Namely the ones just behind B turret, and then the ones just below B torpedo launcher.

You might also consider 30mm weapons: there's an Oerlikon twin belt-fed mount with an enclosed or open cabin to one side (built under licence in the UK by BMARC and seen on various post-Falklands RN ships), and there's also the US Emerlec mounting, which has a manned cabin with podded guns to either side.

Post-Falklands is a bit late for my timeframe; the GDM-C turret is just right.  Relatively new but still in for Vietnam, with (in my opinion) great tracking speed, just over three seconds for a full circle.  Elevation means it'll do fine against small craft as well, -15 is some sweet depressed fire even up real close.

Hm.  Idly, if I wanted to go lighter, what about a ZSU-23 turret?  Again, no on-mount radar, just working from the same idea.

The problem is computing power. You need a fast radar scan rate which reduces the detection range, giving you less than two minutes to detect the threat, evaluate it and react to it. You then have to slew the trackers and/or guns onto target, acquire the target, engage it, evaluate the results and re-engage if neccessary. 1960s radars wern't brilliant at tracking targets at low elevations, so you want optical backup, but frankly, that's better done by a co-axial TV camera on the target tracking radar operated by the same guy who's running the whole engagement from the nice warm CIC anyway, than by a frozen, bored gunner on the mounting who's got to be told when to take over.

I figured that was going to be the killer.  I know you can get good radar direction for some things at the time, and high-altitude targets will work fine, but I'm fully sold on the coax camera.  Put a big zoom lens on it and some stabilization, and you get a great target ID rig as well.  Considering antiship missiles of the era, you either get subsonic cruise shots that should be trackable like an attacking aircraft, or the "screw it we're doomed anyway" shot from a high-angle Kh-22.  Not a whole lot in between in that timeframe, and they're all pretty massive, which helps somewhat.

[Maverick]

I believe that the 75mm mounted in the B-25 was also one-shot and manually loaded ---

Indeed it was, but it wasn't designed to take on bombers or other aircraft, whereas this aircraft was.  One might suggest that a single shot weapon would be adequate for a single strafing pass on a ship whilst attacking an aircraft might require a couple of shots at least.

Regards,

Mav

[Weaver]

As far as the GDM-C goes, I think that's the one - found a pic here of the thing on the stern of a Libyan corvette.  Frankly that's about spot-on, I think, now the big question is whether or not it'd fit in the gun tubs of a Fletcher-class.  Namely the ones just behind B turret, and then the ones just below B torpedo launcher.

I think that Libya was the ONLY customer actually: most customers were keener on either the Swiss mount (easy bolt-to-deck fitting) or the Breda-Bofors twin 40mm, but the Swedish involvement blocked that one from going to some export customers. My book (US Naval Institute World Naval Weapon Systems 1989 by Norman Freidman) says it comes in two flavours, one with a below-deck shank and one for surface mounting. I don't know what the above-deck mounting looks like though: if it's similar to the Breda-Bofors then it's substantial: a one-deck high cylinder.

You might also consider 30mm weapons: there's an Oerlikon twin belt-fed mount with an enclosed or open cabin to one side (built under licence in the UK by BMARC and seen on various post-Falklands RN ships), and there's also the US Emerlec mounting, which has a manned cabin with podded guns to either side.

Post-Falklands is a bit late for my timeframe; the GDM-C turret is just right.  Relatively new but still in for Vietnam, with (in my opinion) great tracking speed, just over three seconds for a full circle.  Elevation means it'll do fine against small craft as well, -15 is some sweet depressed fire even up real close.

I only said "post-Falklands" because that was when the RN started using them: the actual mounting goesback to 1968: http://www.navweaps.com/Weapons/WNBR_30-75_GCM.htm

The Emerlec goes back along way too, and is very popular, with over 150 sold. The US version didn't penetrate the deck either, although most export ones do. IIRC, South Korea used it in exactly the way you suggest, as an add-on for WWII destroyers.  http://www.navweaps.com/Weapons/WNUS_30mm_Emerlec.htm

I figured that was going to be the killer.  I know you can get good radar direction for some things at the time, and high-altitude targets will work fine, but I'm fully sold on the coax camera.  Put a big zoom lens on it and some stabilization, and you get a great target ID rig as well.  Considering antiship missiles of the era, you either get subsonic cruise shots that should be trackable like an attacking aircraft, or the "screw it we're doomed anyway" shot from a high-angle Kh-22.  Not a whole lot in between in that timeframe, and they're all pretty massive, which helps somewhat.

Didn't know that about the USN, though I think they're better served with the 76mm.  Me, I definitely want the dedicated rapid-fire AA capability, rather than the more multirole thing.

Hm.  Idly, if I wanted to go lighter, what about a ZSU-23 turret?  Again, no on-mount radar, just working from the same idea.

I've lumped all these quotes together because they illustrate a general point. There's a fundamental debate been going on for years about CIWS weapons between those who advocate high-rate small calibre weapons and those who think bigger, longer ranged guns are better. Small weapons like Phallanx have the advantage of neat mountings with on-mount fire-control that makes them easy to re-fit to exisiting ships. However the problem is their short range: shooting down a subsonic 1300lb Exocet at 300 yds is okay 'cos it crashes into the sea, but shooting a diving supersonic 5000lb missile to smithereens at 300yds is ineffective because the smithereens still hit you at over mach 1 and do almost as much damage as if they were still in one piece. This is why Breda and Bofors have been pushing the Fast Forty with it's proximity-fused ammo for years. The Italian navy is the principle exponent of using bigger guns to engage further out, and now uses the 76mm Super-Rapid as it's anti-missile weapon. Although this argument came after the adoption of small guns, it actually reflects the same considerations that drove the move from 40mm to 3" in the USN at the end of WWII in response to Kamakazi attacks.

One thing you might consider for your re-fitted WWII destroyer therefore is the older OTO-Melara 76mm weapon wheich preceded the 76/62 Compact. It wouldn't fit in every 40mm slot one-for-one, but I bet you could get a fair few on-board. http://www.navweaps.com/Weapons/WNIT_3-62_MMI.htm

[icchan]

Well, the way things are going for this fictional military and whiffery, there's a preference to the higher caliber rounds.  I thought about it, and realized that you can hit with a lot of small rounds, but the vital bits that would be affected aren't that large - and neither is the pop of the 20mm shell.  It has to hit very close, while the 30mm can be further away from the particular vital spots and still hit them.  It makes the "kill area" of the target larger, so there's an advantage to the bigger shell.  That may explain the mean-rounds-to-kill variation.

So I'm all for the 35s, as they're "only slightly smaller" than the 40s they replace and yet are still explosively happy.  And I can only imagine the pain you could cause with them to a small attack boat that strayed too close...

[rickshaw]

The main problem with attempting to retrofit modern, larger calibre weapons onto smaller, older platforms is that the modern, larger calibre weapons (>=40mm) require substantial below decks ammunition handling equipment and storage in order to gain the advantages you're seeking in higher rates of fire.  Smaller calibre weapons have much smaller needs for such things - although even their power consumptions are substantially higher than the older weapons they replace so there would be a need to considerably increase power generation, not only for the weapons and their mounts but also their handling machinery and electronics to run the whole lot.

I'd be very surprised to find many WWII era ships still around today, though.   Most would have been replaced by the 1970s when their machinery and hulls were worn out.  Even the US Navy with its substantial wealth was finding it difficult to maintain its WWII era DDs in service by the 1960s and was looking for the substantial number of hulls required to replace them.

[dy031101]

I'd be very surprised to find many WWII era ships still around today, though.   Most would have been replaced by the 1970s when their machinery and hulls were worn out.  Even the US Navy with its substantial wealth was finding it difficult to maintain its WWII era DDs in service by the 1960s and was looking for the substantial number of hulls required to replace them.

Speaking of which, I was personally thinking of the other way around- maybe, say, some country wanted to develop their shipbuilding industry, so they salvaged old guns and maybe some sensors (the radars of PRC's first indigenous frigates came from decommissioned torpedo boats, so I don't think the idea is as outrageous as it sounds) and put those stuffs onto newly-designed hulls: the hulls could be of comparable size and/or mostly-comparable weapon fits, could be of a similar configuration, may or may not have more-efficient mobility, may or may not have better sea-keeping qualities, may or may not have better accommodation, but at least the machinery would be all-new.

Then perhaps new close-in defense cannons could be fitted to those hulls as well......

(P.S. The 35mm GDM-A mount actually looks to me like a smaller 76mm Compact...... which I found kinda cool  )

[rickshaw]

That may work for the first or perhaps even second generation but as the PRC has show, if you want to compete with the big boys, you need the same toys they've got which mean advanced radars and sonars, advanced weapons, advanced hull forms, etc.