Naval Gun Projects

[cluttonfred]

I am reviving this thread from a couple of months ago with a question:

Why, in the naval or land-based context, does the shotgun concept seem to be rarely if ever to be used in anti-aircraft weapons?

Legality aside, no one would hunt a duck with an accurate, small caliber machine gun, so why don't close-in weapons systems targeting aircraft and missiles use, in effect, big shotguns? Even at modest velocities that seems more effective at putting up a "wall of lead" than an autocannon. Perhaps some sort of variable choke would allow adjusting the pattern for various ranges? It seems like that would substantially reduce the technical challenge of hitting a sea-skimming missile, yet I have never heard of it being used.

Enlighten me!

 

[red admiral]

I would think that the typical engagement ranges would reduce the accuracy and lethality of a small number of subprojectiles.

The Spanish Meroka weapon here is sort of similar but uses multiple barrels instead of one large one. Range is pretty short though.

 

[RP1]

Re: Naval Gun Projects (Shotguns)

Why, in the naval or land-based context, does the shotgun concept seem to be rarely if ever to be used in anti-aircraft weapons?

Shotgun projectiles have been proposed for anti surface use:

http://www.dtic.mil/ndia/2003gun/steel.pdf

"5-Inch Shotgun Projectile", L Steelman, 2003

The AHEAD (Advanced Hit Efficiency And Destruction) rounds could be regarded as shotgun-esque, as they release pellets rather than casing fragments, and rely as much on the target velocity as the pellet velocity:

http://www.rheinmetall-defence.com/index.php?lang=3&fid=2177

Also, of course, the IJN developed 18 inch "sankaidan" incendiary shrapnel anti-aircraft rounds for the Yamato class vessels. These would explode under the target creating a cone of shrapnel. However, as noted below, they were not safe and exploded in the gun barrel.

http://www.navweaps.com/Weapons/WNJAP_18-45_t94.htm

A conventional shotgun cartridge, where the shot is released directly from the barrel, would be ineffective against most aerial targets due to the poor ballistics of the pellets - this is why shotguns are safer for hunting than, say, rifles, as the shot looses lethality very quickly. The pellets would thus have low penetration and subsequent internal effects on the target.

The shotgun projectile requires an increase in accuracy over a conventional fragmentation round, in that the cone of shot produced has to be pointing at the target - with a (roughly) spherical burst the round may be effective even if it is alongside the target.

RP1

 

[Orionblamblam]

Legality aside, no one would hunt a duck with an accurate, small caliber machine gun,

Not necessarily true. I live within earshot of a waterfowl hunting area, and every now and then during duck hunting season I hear fully automatic weapons opening up. I too question the value of using an M-16 or an AK-47 to hunt ducks, but there it is.

 

[tinlail]

I am reviving this thread from a couple of months ago with a question:

Why, in the naval or land-based context, does the shotgun concept seem to be rarely if ever to be used in anti-aircraft weapons?

Legality aside, no one would hunt a duck with an accurate, small caliber machine gun, so why don't close-in weapons systems targeting aircraft and missiles use, in effect, big shotguns? Even at modest velocities that seems more effective at putting up a "wall of lead" than an autocannon. Perhaps some sort of variable choke would allow adjusting the pattern for various ranges? It seems like that would substantially reduce the technical challenge of hitting a sea-skimming missile, yet I have never heard of it being used.

Enlighten me!

I suspect the main issue is one of reloading speed. Since ducks rarely bomb hunters let another duck fly by is no great loss after downing the first one. As reloading speeds increase your weapon starts to take on the characteristic of a machine gun.

 

[pathology_doc]

And hit the pilot, though that might be too late to stop a Kamikaze

The equivalent of a CIWS causing missile warhead detonation is AA fire exploding a Kamikaze's bombload, yes? The difference is that in a missile, the warhead forms a significant proportion of vehicle volume, so that anything which can hit the vehicle is likely to detonate it; whereas the warhead (e.g. underslung 500lb bomb) forms only a small part, volume wise, of a diving A6M.

But a missile weighing several thousand pounds is a difficult target to stop in anyone's language, surely. I suspect that if the current US Navy had to face WW2 Kamikazes, most of the surface-to-air kills would be made by SM-2 or RIM-7.

 

[RP1]

Interesting problem this. Putting fragment holes in an aircraft's wings won't unnecessarily cause it to miss it's target, unlike a missile where the control and lifting surfaces are quite small. Unless you can get a controlled fragmentation pattern a HE blast warhead might be preferable - the resulting loss of an entire control surface would be likely to make the Kamikaze miss its intended target. I note from designation-systems.net that the early USN SAM Lark used a HE warhead - perhaps that is why?

RP1

 

[Jemiba]

"..the resulting loss of an entire control surface would be likely to make the Kamikaze miss its intended target.."

It's a matter of the distance, at which the target, Kamikaze or missile can be hit and so a matter of
weapons range. If the target is too close, it won't need any more flight control, as it just will follow
on the ballistic trajectory and hit nevertheless. As I've read, that was exactly, what happened to a
lot of Kamikazes, which still hit the target, although wings and control surfaces were shot away and
the "guidance system", the pilot, probably already out of action. In consequence, the USN moved away
the 20mm AA guns from their ships, keeping only the 40mm, which proofed not to be effective enough,
too, to secure total disintegration of the attacker.

 

[Demon Lord Razgriz]

Sorry to go slightly off topic, but does anyone have an idea what the caliber is going to be on a full-size Naval Rail Gun? I've looked and I can't find it.

 

[sferrin]

Sorry to go slightly off topic, but does anyone have an idea what the caliber is going to be on a full-size Naval Rail Gun? I've looked and I can't find it.

I doubt they've progressed to the point that there's actually an answer to be had there.

 

[smurf]

http://www.youtube.com/watch?v=y54aLcC3G74
that projectile looks to be about 4 to 5inch, and 5in is a US standard

 

[RP1]

Just a quick one: Advert for the GAU-8 based "Satan" CIWS, from USNI Proceedings October 1985.

RP1

 

[sferrin]

Just a quick one: Advert for the GAU-8 based "Satan" CIWS, from USNI Proceedings October 1985.

RP1

Looks like they combined the sensor and gun into Goalkeeper.

 

[Lauge]

I live within earshot of a waterfowl hunting area, and every now and then during duck hunting season I hear fully automatic weapons opening up.

Wouldn't that most likely be the ducks returning fire?

Regards & all,

Thomas L. Nielsen
Luxembourg

 

[TomS]

Looks like they combined the sensor and gun into Goalkeeper.

The gun mount in Goalkeeper was actually a General Electric design (EX-83) and was proposed for quite a few different CIWS applications in the 1980s -- Goalkeeper, SATAN, SAGEM's SAMOS, VSEL's Sea Dragon (referenced earlier in this thread), and possibly more.

 

[sferrin]

Looks like they combined the sensor and gun into Goalkeeper.

The gun mount in Goalkeeper was actually a General Electric design (EX-83) and was proposed for quite a few different CIWS applications in the 1980s -- Goalkeeper, SATAN, SAGEM's SAMOS, VSEL's Sea Dragon (referenced earlier in this thread), and possibly more.

The one in the 2nd post in this thread is still my favorite.

 

[RP1]

A note on the calibre of Rail Guns. I recently co-authored a paper on "The Impact of Integrated Electric Weapons on Future Warship Design" at INEC 2010 and dug up a lot of information on the on going EM Rail Gun projects (most of which are IEEE papers and so can't be disseminated here).

Calibre is a poor indicator of EMRG firepower and "flight mass" and muzzle velocity, together giving muzzle energy, are more normally used, since one aim is to achieve target destruction through kinetic energy effects alone. The most complete recent figures I have (from 2003) are a flight mass of 16.4kg, launch mass of 21.9kg (the projectile is launched in an insulating sabot and conducting armature), MV of 2000m/s and bore diameter of 146mm. The ~63MJ system frequently alluded to has a similarly sized projectile with an increased MV of 2500m/s. [1][2]

RP1

[1] 21. McFarland, J & McNab, I R, “A Long Range Naval Railgun”, IEEE Transactions on Magnetics, Vol. 39, No. 1, January 2003
[2] 25. Ellis, R, “Exploring the Possibilities of a Naval Electromagnetic Rail Gun”, 38th Annual Gun & Ammunition Symposium March 24 – 27, 2003

 

[TomS]

The gun mount in Goalkeeper was actually a General Electric design (EX-83) and was proposed for quite a few different CIWS applications in the 1980s -- Goalkeeper, SATAN, SAGEM's SAMOS, VSEL's Sea Dragon (referenced earlier in this thread), and possibly more.

The one in the 2nd post in this thread is still my favorite.

Nice gun, but that's not a relative of EX-83 at all. The 35mm case telescoped CIWS was based on the Phalanx mount, which is quite different from EX-83.

 

[uk 75]

In a 70s pic of .U.S.N guns a 3" gun in spherical mount next to a mk 65. Need more info

 

[thebig C]

Hey

Does anybody have any info on a Bofors 76mm naval gun. It was used by Norway on the Storm class patrol boats and Singapore on their Vosper FPBs. It possibly derived from a WWII aa gun. Anyway, it is very elusive and there are few references to it on the Net. It featured a very distinctive half-egg shaped turret. Going on the vintage of the vessels involved is it safe to assume that Bofors abandoned it in the 1960s to concentrate on the 57mm?

Also, and I might be dreaming this one), I have a vague recollection of reading about a new turret (possibly of intermediate calibre betweem Oto Malera 76mm and the French 100mm), in an illustration/mock up it sort of resembled an Oto Malera in that it was cylindrical but featured a much flater top. Am I dreaming?

C

 

[TomS]

Hey

Does anybody have any info on a Bofors 76mm naval gun. It was used by Norway on the Storm class patrol boats and Singapore on their Vosper FPBs. It possibly derived from a WWII aa gun. Anyway, it is very elusive and there are few references to it on the Net. It featured a very distinctive half-egg shaped turret. Going on the vintage of the vessels involved is it safe to assume that Bofors abandoned it in the 1960s to concentrate on the 57mm?

The post-war Bofors 76mm gun (TAK76) was one of the very few low-angle guns produced in that era, suitable only for surface fire. It's possible that it was derived from the M1927 anti-aircraft gun, but I doubt it given its low-angle only design. I believe it fired the same ammunition as the US 3-inch/50 gun. As you surmise, it was displaced by the SAK57 dual-purpose gun, which was heavier but far more versatile. I think I've got more info in one of my older reference books, but I'm getting ready to move, so it may not be accessible.

 

[thebig C]

Hey

Does anybody have any info on a Bofors 76mm naval gun. It was used by Norway on the Storm class patrol boats and Singapore on their Vosper FPBs. It possibly derived from a WWII aa gun. Anyway, it is very elusive and there are few references to it on the Net. It featured a very distinctive half-egg shaped turret. Going on the vintage of the vessels involved is it safe to assume that Bofors abandoned it in the 1960s to concentrate on the 57mm?

The post-war Bofors 76mm gun (TAK76) was one of the very few low-angle guns produced in that era, suitable only for surface fire. It's possible that it was derived from the M1927 anti-aircraft gun, but I doubt it given its low-angle only design. I believe it fired the same ammunition as the US 3-inch/50 gun. As you surmise, it was displaced by the SAK57 dual-purpose gun, which was heavier but far more versatile. I think I've got more info in one of my older reference books, but I'm getting ready to move, so it may not be accessible.

Hey Tom

Thanks a million for that. I could find very little info, and, it seems that this gun was used for relatively few applications. Perhaps because of the drawbacks you suggest.

C

 

[Abraham Gubler]

Thanks a million for that. I could find very little info, and, it seems that this gun was used for relatively few applications. Perhaps because of the drawbacks you suggest.

They weren't drawbacks but what it was designed to do. It was a gun to destroy other fast attack boats and was in the vein of the 6 Pounder (57mm) gun on British MGBs during WWII. At that time (the 50s and 60s) there were very few medium calibire (57-76mm) anti aircraft guns and all of them were usually huge. It wasn't until the Oto Gun (76mm) and the Bofors SAK 57 fielded in the mid to late 1960s that fast attack boats could carry a gun bigger than the Bofors 40mm for anti aircraft fires. So by the time demand for western fast attack boats really caught on the late 60s and 70s there were excellent dual purpose guns to arm for air defence and sinking other boats.

 

[TomS]

Thanks a million for that. I could find very little info, and, it seems that this gun was used for relatively few applications. Perhaps because of the drawbacks you suggest.

Found more in a copy of Jane's Naval Weapon Systems. Per Jane's, the gun was a private venture by Bofors begun in 1962, and was adapted from a 76mm/50 coast artillery gun, but modified to 3-inch (a very minor change in dimension) "because that ammunition was more commonly used by navies." The ammunition is described as a fixed cartridge weighing 11.3kg, which could mean it's not the US 3-inch/50 round, which apparently weighed 10.9 kg complete (however, I see some variation between sources). Muzzle velocity is 825m/s, nearly identical to the US round (2 m/sec difference).

The turret is fully automated, fed from a motor-driven hoist to a below-deck magazine with 100 rounds. Two loaders move ammo from the magazine to the 5-round feed drum, which in turn feeds the vertical hoist. From there, a transfer arm in the turret moves the rounds to the loading tray and the rounds are then rammed home. RoF is 30 RPM. Traverse was 350º with elevation limits of -10 to +30º. Range was credited as 6.8 nautical miles (12.6 km). The turret is roughly 1.5 m high, with a penetration below decks of 2.9 m. Total mount weight was 6.5 tons.

The image below is from Jane's, but I think it was probably originally from the manufacturer.

 

[Petrus]

the gun was ... adapted from a 76mm/50 coast artillery gun, but modified to 3-inch...

The Swedish used, if my memory serves me well, coastal guns in 75mm rather than 76mm calibre. They were automatic weapons as well and their cupolas seemed quite similar to those of the 76mm ship gun.

By the way, the drawing is really breathtaking. Thank you for posting it.

Piotr

 

[TomS]

Makes sense. There was a Swedish 75mm/57 gun used mainly in fixed installations that was fielded in 1957; it seems a likely candidate for adaptation to US 3-inch/50 ammunition (basically similar velocity and shell weight, despite the minor caliber change). Probably the Jane's reference to 76mm is a typo or mistake.

http://en.wikipedia.org/wiki/7.5_cm_tornpj%C3%A4s_m/57

 

[thebig C]

Hey TomS

Thanks for those posts!! Some great info there.

The start date for this project of 1962 is interesting because off the top of my head I can only think of a handful of vessel classes that used them. Namely, the Storm Class patrol boats and Sleipner Class corvettes of Norway and on the Vosper FACs of Singapore. They are all of 1960s vintage meaning that Bofors must have ceased marketing this weapon after just a few years.

When you look at the low ROF compared the Bofors 57mm mk i (developed around the same time early 1960s) and the slightly later (mid 1960s) Oto Malera 76mm its perhaps unsurprising that it was given the heave-ho! To say nothing about its lack of adaptability to different tasks as you have pointed out!

It is worth noting though that the imensely successful Oto 76mm of today is the second attemt. The original 76mm "allargato" gun was pretty unsuccessful, being ordered only by the Italian Navy. It does make you wonder though, given that Oto took a couple of attempts to get things right, if Bofors had persisted they might just have produced something excellent and really dominated the medium calibre market. Not exactly a pipedream when you consider so of the great guns they have produced!

Its probably a bad reference, but just look at the TAK120. It was developed, as with the TAK76, in 1962 as a private venture. It was only adopted by Finland (Turunmaa Class 1960s) and Indonesia (Corvettes early 1980s). In all likelyhood it was harmed by the Swedish decision to disgard all vessels larger then torpedo/missile boats from 1968 onwards. Anyway, it was 120mm and managed 80!! rounds per minute. A staggering rof for a gun of that vintage!

http://www.navweaps.com/Weapons/WNSweden_47-46_TAK120.htm

C

 

[TomS]

It's interesting that the 120mm single also failed to gain much success (a couple of Finnish ships and three for Indonesia is all, IIRC). I suspect that it could not have been terribly reliable at full speed; most of the other extremely fast guns in that general size range had issues with jamming and were significantly derated.

I've had a conversation with some other folks and am now convinced that the TAK 76 used US pattern 3-inch/50 ammunition. Tony Williams (Jane's Ammunition Handbook, among other things) says that Norway was making a 3-inch/50 round with Bofors-style designations that exactly matches the measurements of the US round.

 

[cluttonfred]

That TAK120 had only ten ready rounds in two, five-round magazines? That seems pretty dicey if you have only five rounds per target type, even if they are big shells.

 

[Petrus]

That TAK120 had only ten ready rounds in two, five-round magazines? That seems pretty dicey if you have only five rounds per target type, even if they are big shells.

Somewhere (a Polish magazine) I've read that those magazines were reloaded manually. Could you confirm this information?

Piotr

 

[cluttonfred]

Per link in thebigC's post...

Sweden
120 mm/46 (4.7") TAK120
Updated 18 November 2006
--------------------------------------------------------------------------------
A fully-automatic weapon intended for large Fast Attack Craft (FAC). Developed on a private-venture basis from an anti-aircraft field gun. Uses a water-cooled barrel with a replaceable liner and a vertical-sliding breech block, which opens downward during recoil. The gun feeds alternatively from two magazines, one on each side of the barrel. Each of these magazines holds five rounds. This arrangement allows for two different kinds of ammunition to be loaded so that the gun can be immediately switched between ammunition types. The automatic loader uses a spring-powered rammer, which is cocked by the recoil forces.

 

[TomS]

Jane's gives slightly different info about the TAK 120 L/46 ammunition supply. It says there were magazines on each side of the gun consisting of four compartments with five rounds each. These in turn supported a pair of feed tables, each holding six rounds. That's either 32 or 52 rounds on mount, depending on how you interpret it (4x5 total or 4x5 on each side). Those rounds could then be manually reloaded in 2.5 minutes by two human reloaders. The gun would have to return to a loading position for this evolution.

 

[thebig C]

Jane's gives slightly different info about the TAK 120 L/46 ammunition supply. It says there were magazines on each side of the gun consisting of four compartments with five rounds each. These in turn supported a pair of feed tables, each holding six rounds. That's either 32 or 52 rounds on mount, depending on how you interpret it (4x5 total or 4x5 on each side). Those rounds could then be manually reloaded in 2.5 minutes by two human reloaders. The gun would have to return to a loading position for this evolution.

I would love to get a confirmation because that is some disparity. A 32-52 round capacity makes it a much more attractive proposition then a 5 round capacity!

I think you could be right about the jamming issue. Particularly on weapons of that vintage the quoted stats were often a little "theoretical"!

C

 

[TomS]

I would love to get a confirmation because that is some disparity. A 32-52 round capacity makes it a much more attractive proposition then a 5 round capacity!

Friedman's Guide to World Naval Weapon Systems says the TAK 120 turret had two 25-round magazines, one on each side of the breech. That looks pretty consistent with the Jane's description, give or take one round in the feed trays (possibly the difference between a round "up the pipe" or not).

 

[Petrus]

As for the TAK120, the gun was based upon land-based anti-aircraft automatic Lvakan 4501 gun, which had two magazines (each side of the breech) each with 24 rounds (take a look at photos attached), so it would be quite logical that the feeding system had been retained in the naval mounting.

However in a Swedish forum https://www.flashback.org/t1058569p10 I've found information on the ammunition capacity of the TAK120, which we know from http://www.navweaps.com/Weapons/WNSweden_47-46_TAK120.htm:

12cm L/46 TAK120 hade dock reducerad ammunitionskapacitet jämfört med 12 cm lvakan 4501, med 10 granater i magasinen och 16st i tornets bakkant för 12cm L/46 TAK120 vs. 48 granater i magasinen för 12 cm lvakan 4501.

The text doesn't seem to be simply copied from another source and its author says about reduction of the TAK120's ammo capacity as compared to the Lvakan 4501, so perhaps indeed the naval mounting had fewer ready to fire ammunition than the land-based gun.

Anyway it would be really interesting to know how the mounting was actually arranged internally.

Piotr

 

[TomS]

Thanks for that reference; I was not familiar with the land-based gun the TAK 120 was based on. Wish there was an easy way to reconcile the various sources, but they seem mutually incompatible.

 

[TomS]

A quick update. Tony DiGiulliani from Naval Weapons let me have a look at an official Bofors data sheet for the TAK 120 and it confirms the Jane's figures of 52 rounds in magazines and feed tables. There were also 16 rounds in the turret rear. These rounds were probably (my guess) a ready reserve in case of trouble with the hoist that would bring reserve ammunition up to the turret from stowage magazines. The hoist could only bring ammo up into the turret while the later was in the loading position.

Sadly, Tony was given the data sheet on the condition that he not post it online, so I must honor that constraint. He said he would update his website accordingly.

 

[Petrus]

Tony DiGiulliani from Naval Weapons (...) said he would update his website accordingly.

Do you mean www.navweaps.com?

Piotr

 

[TomS]

Yes.

Edit: Please do not bug Tony asking for copies of this. He shared it with me because we've known each other (online) for many years and he's a bit annoyed with me that he's now getting other folks he does not know mailing to request the file.

 

[Brickmuppet]

This sounds very similar to the ammo system of the Bofors 57mm weapon which makes sense. It also needs to move to a fixed firing position to reload its ready use trays.