6"/70 S.B. Mounting

[LiBF4]

When browsing Vickers Tyne & Wear Archive I noticed a really intersting and obscure design proposal. Not only by the strangely long barrel, sci-fi look turret (this is a 1946 drawing), but also the insane stats and unique operating mechanism. I also cannot find any information of this proposal online.
The file was archived in Tyne & Wear Archive with identification number DS.VA/6/25/13. It contains 2 page brief description, 1 mounting design plans and 1 firing timetable.

The turret is capable of firing at 24rpm per barrel, adding up to 48rpm per turret: faster than the 20rpm for 6"/50 Mark N5 gun. Other stats of the projectile are unknown. But considering later 5"/70 N1 with similar long barrel design, or the 6"/50 N5 firing superheavy shells, this gun might also fires a superheavy 6" shell at very high muzzle velocity. With 1inch thick shield the empty revolving weight was 179 ton while with 2 inch thick shield weight was 208ton -- A really low weight considering the rotating structure of real built 6" QF Mark 26 mount is 171ton.

This gun lacks water cooling systems. Considering such high rate of fire the intense heat may soon lead to a forced cooldown.

The gun seems to be fed from 2 swinging magazines, one is being reloaded from the bottom magazine while another is loading the gun at the gun position. The loading mechanism seems closer to those used on later fast firing N1 projects.I am, however, really having trouble understanding the working mechanisms, although a long documentary demonstration was provided. In my view one 4-round swinging magazine can only reload the gun on the either side, given the timechart, my assumption makes the twin turret only able to fire one of the gun simultaneously.

As far as I know, no projects were planned to use such mounting.

In addition, I tried to figure out what "S.B" abbreviation means. This is highly unlikely to be "smoothbore".


In order to better discuss the design background and working mechanisms I will just directly put the origial description and two drawings here. All photos are from the Tyne & Wear Archives. Due to copyright concerns at the moment I won't upload the high resolusion scan. I will delete the post if a violation to the copyright was confirmed.

 

[robunos]

My guess is that 'S.B.' means 'Ship Board', or 'Ship Bourne'.

my assumption makes the twin turret only able to fire one of the gun simultaneously.

This may be a way of controlling the heat issue that you mentioned . . .

cheers,
Robin.

 

[Cthell]

For high-angle fire I believe each gun has 2 4-round transfer magazines (one on each side of the barrel), but each magazine can only be loaded with 2 rounds at a time from an upper ammunition loop (with a seperate loop for each gun) via the 2 loading hoists. That enables one transfer magazine to be loaded (in 2 stages) while the other feeds the gun.

For low-angle fire, there is a seperate single hoist per gun that only feeds the outermost transfer magazine - this is manually loaded from the level of the lower ammunition loops (but from a separate magazine located within the automatic ammunition chain.

That means for high-angle fire, both guns can fire simultaneously and continously, while for low-angle fire they can only fire in either single-shot or 4-round burst (depending on whether they load the whole transfer magazine and then fire, or just load/transfer/fire as quickly as the crew can feed shells into the hoist)

 

[JFC Fuller]

The turret is capable of firing at 24rpm per barrel, adding up to 48rpm per turret: faster than the 20rpm for 6"/50 Mark N5 gun. Other stats of the projectile are unknown. But considering later 5"/70 N1 with similar long barrel design, or the 6"/50 N5 firing superheavy shells, this gun might also fires a superheavy 6" shell at very high muzzle velocity. With 1inch thick shield the empty revolving weight was 179 ton while with 2 inch thick shield weight was 208ton -- A really low weight considering the rotating structure of real built 6" QF Mark 26 mount is 171ton.

This gun lacks water cooling systems. Considering such high rate of fire the intense heat may soon lead to a forced cooldown.

The gun seems to be fed from 2 swinging magazines, one is being reloaded from the bottom magazine while another is loading the gun at the gun position. The loading mechanism seems closer to those used on later fast firing N1 projects.I am, however, really having trouble understanding the working mechanisms, although a long documentary demonstration was provided. In my view one 4-round swinging magazine can only reload the gun on the either side, given the timechart, my assumption makes the twin turret only able to fire one of the gun simultaneously.

As far as I know, no projects were planned to use such mounting.

In addition, I tried to figure out what "S.B" abbreviation means. This is highly unlikely to be "smoothbore".

Thank you for posting these, I have never seen them before and they are fascinating.

S. B. may be smoothbore, the high muzzle velocity, long barrel and date put it in the MCDP/Green Mace early timeline and these guns were planned with a smooth bore at points in their development, see this thread.

I don't see any evidence in the pictures you posted for the idea that only one gun could fire at a time. The description states that each gun had two swinging magazines, one magazine would be loading the gun whilst the second was being replenished. The time chart is for a single gun.

As you say, there is no indication of any form of water cooling, at a sustained 24 rpm the barrels would soon overheat. However, the text states that the lower belts are fed manually, e.g. rounds were to be man handled into them, and that the automatic system only held a total of 96 rounds per gun. Therefore, after the first four minutes the rpm would fall to whatever speed the magazine crews could load rounds into the lower belts.

Does the document state the shell weight anywhere?

 

[LiBF4]

post edited for easier read.

 

[LiBF4]

For high-angle fire I believe each gun has 2 4-round transfer magazines (one on each side of the barrel), but each magazine can only be loaded with 2 rounds at a time from an upper ammunition loop (with a seperate loop for each gun) via the 2 loading hoists. That enables one transfer magazine to be loaded (in 2 stages) while the other feeds the gun.

For low-angle fire, there is a seperate single hoist per gun that only feeds the outermost transfer magazine - this is manually loaded from the level of the lower ammunition loops (but from a separate magazine located within the automatic ammunition chain.

That means for high-angle fire, both guns can fire simultaneously and continously, while for low-angle fire they can only fire in either single-shot or 4-round burst (depending on whether they load the whole transfer magazine and then fire, or just load/transfer/fire as quickly as the crew can feed shells into the hoist)

Ahh yes I finally noticed that it is each gun, not each turret, has 2 4-round "swinging magazine". This answers how the gun keeps 24 rpm fire. Thanks for your further explaination.

 

[LiBF4]

Thank you for posting these, I have never seen them before and they are fascinating.

S. B. may be smoothbore, the high muzzle velocity, long barrel and date put it in the MCDP/Green Mace early timeline and these guns were planned with a smooth bore at points in their development, see this thread.

I don't see any evidence in the pictures you posted for the idea that only one gun could fire at a time. The description states that each gun had two swinging magazines, one magazine would be loading the gun whilst the second was being replenished. The time chart is for a single gun.

As you say, there is no indication of any form of water cooling, at a sustained 24 rpm the barrels would soon overheat. However, the text states that the lower belts are fed manually, e.g. rounds were to be man handled into them, and that the automatic system only held a total of 96 rounds per gun. Therefore, after the first four minutes the rpm would fall to whatever speed the magazine crews could load rounds into the lower belts.

Does the document state the shell weight anywhere?

Yes reminded by other members. Each gun has two 4 round feeders.

However I doesn't really think this is a smoothbore gun. Indeed, Smoothbore was the only abbreviation I can think of before really saw the content. However in the drawings, the projectiles semms to be the ordinary ammo for a rifiled gun. Smoothbore version Green Mace was equipped with special fin-stablized ammo to obtain good accuracy at long ranges. In addition the very early date: 23rd May, 1946, also weaken its connection with the following MCDP projects and Green Mace. But they could still having a connection for all being fast firing anti-air focused weapon.

Unfortunately the file didn't mention anything about the ammunition. No weight, muzzle velocity information was provided. However due to roughly measuring from the drawings, the catridge (shown in yellow) is almost 1.3 meters in length. The catridge length for British Mark N5 was not known, but for American DP Mark 16 gun it is 152x970mm, indicating that the gun still holds more propellant than other guns of the similar caliber. With such a long barrel, the muzzle energy could be extremely high.
For the watercooling issues, it's true that the gun will quickly run out of ammo storage to a forced cooldown. In a different document about the Vickers Mark N (R) Naval gun, there's a statement:

..."46 rounds is considered to be sufficient to meet any demand likely to arise in action, before a pause occurs, during which reloading from the ready-use storage can take place."

Although build with different caliber, their general purpose could be the same. The ammo storage was pretty low but still sufficient to deal with most circumstances. In other words, maybe long lasting firing was not a priority during the concept design progress. They're supposed to deal with the threat in minimum bursts, allowing reloading and cooling down before the next threat show up.

Furthermore, I also found the design drawings representing the model mount shown in the link you posted. Being the 4"45 cal barrel option in the design of Vickers Mark N (R). The final exported 4"/62 version use the same structure but the turret shield was extended to fully protect the loading mechanism. Those are beyond this topic so I will pause. Too much newly discovered projects in the visit and I will gradually look into and share them in the future.

 

[JFC Fuller]

The other notable feature is that all 31 low angle rounds in the system are described as being manhandled. Combined with the 70 cal barrel and 85 degree elevation it leaves the impression that this was an AA weapon that had a secondary anti-surface capability. That in turn reinforces my opinion that S.B. refers to smoothbore, not that the barrel would have been smoothbore over its entire length but that it would have been only gradually rifled, as in the 3.7" Mk.VI.

Interest in high velocity, high RoF heavy guns started almost as soon as the war was over (and I suspect before). The 5"/70 was being considered for future destroyer construction at least as early as August 1948 and the early MCDP work was undertaken on the same contracts that had been put in place for the much less ambitious 5.25" Mk.IV during the war. This proposal may reflect very early RN interest in such weapons.

Curiously, the turret shape is reminiscent of the turrets drawn on this "Warship of the Future" artists impression. I am not suggesting that they are intended to be this mount, for a start it would be much larger, but the shape might have been an inspiration for them on what looks like an odd mash of different features.

The Vickers Mark N (R) drawing you posted is the same as the one at Kew in the file that contains the RN view of it (they didnt like it).

 

[Tzoli]

Add that this is a 6" barrel which is plenty for proximity fuzes and with such burst fire you can easily shoot down torpedo and dive bombers.

 

[zen]

6" takes us firmly into dual purpose capability. Such a mount would give a Cruiser quite a potent Anti-ship capability.