Sir John Valentine Carden survives.

Status
Not open for further replies.

Mark1878

Donor
I'm afraid that I've been guilty of what Catholics call the sin of presumption.
So, Carden's original back of the envelope mentions using "our M/C gun". Which I presumed to be Machine Cannon, therefore the 2-pdr pompom. The tank sold to the Latvians with Vickers own 2-pdr in the turret which I've adapted onto the Carden A11 was also presumed by me to be the pompom.
Now though, having looked at the Osprey book British Anti-tank Artillery 1939, Vickers own 2pdr was an alternative design to the Woolwich 2pdr which eventually was put into production. Vickers own gun had orders of only 44, then the improved Woolwich design replaced it for an order of 812. So the Latvian tanks will have been given the failed to be ordered Vickers 2pdr, which makes sense as it would otherwise be the latest British army gear sold to a foreign buyer.
I think I can still handwavium the pompom as I still can't find what M/C stands for. Medium Calibre?
Anyway, just though I'd confess my sin.
Allan.
View attachment 602077
Doesn't this also suggest why the Army didn't like Vickers guns as they had proof that ROF could do better.
 
Machine cannon gun makes no sense. It is either cannon or gun, not both.
"An autocannon, automatic cannon or machine cannon is a fully automatic gun that is capable of rapid-firing large-caliber (20 mm/0.79 in or more) armour-piercing explosive or incendiary shells, as opposed to the smaller-caliber kinetic projectiles (bullets) fired by a machine gun."

The term was used for guns which could rapid fire "Cannon" ammunition (ie, anything large enough for a useful HE round, normally over 20 mm)
 
An automatic cannon like the pom-pom would he a poor substitute for the HE firepower a 3+ inch CS howitzer could provide, and it would probably be harder to aim and use, especially in a tank.
 
An automatic cannon like the pom-pom would he a poor substitute for the HE firepower a 3+ inch CS howitzer could provide, and it would probably be harder to aim and use, especially in a tank.
The 3" howitzer was mostly equipped with smoke rounds. AIUI that was because its origin as a howitzer made it very difficult to actually hit anything reliably. I am inclined to think the Pom-pom might be better for this application.
 
So the Vickers M/c gun some thoughts.

M/c (if it is M/c and to me it does look likely) could have a few meanings.
The first is it is actually the Vickers M gun internal model c perhaps. You already have the Vickers K and the Vickers S so the Vickers M isn't such a stretch. The fact we don't know about this gun is possibly because it was only ever in limited development and never progressed very far hence the /c part. basically the third iteration of a design that is on the back burner. What the Vickers M might be though, who knows. An automatic cannon based on the pom pom is as good a guess as any.

The second is it could also be Machine cannon so a variation of the pom pom perhaps but Carden was looking at a single shot version. Then you have a Gun based on the machine cannon ammo? Not the best theory but could be true.

The third is again it is Machine cannon and the gun added afterwards was just a slip by Carden. Entirely plausible, it wasn't an official document but a hastily scribbled note by the looks of things so a small mistake or two is to be expected.

Just some thought's but either way the pom pom isn't some massive Wank or completely implausible so I'd stick to that personally. It also potentially gets away from some of the animosity of E M C Clarke as it isn't a newly designed gun and rather a repurposed existing one. Anyway Keep up the good work Allan, nice post on solving the engine issue as well, I'm impressed.
 
While not so much use against tanks (although if they are modifying the HV 2-pdr AA ammo it has a useful mv), it would be devastating against non-armoured transport and targets. Which of course are the ideally intended targets for exploitation tanks
 
Just my random thought, but in reading about British cannons, I've never seen the term "machine cannon".
I've seen "autocannon" and "automatic cannon", but not machine cannon.
 
Just my random thought, but in reading about British cannons, I've never seen the term "machine cannon".
I've seen "autocannon" and "automatic cannon", but not machine cannon.

Is that in period documents or modern books/papers etc looking back?. Also are the official documents or private ones. There is a big difference between an author using modern terminology to describe period items and the period terminology. See SMG/submachine gun and machine carbine for Britain, I almost included that in my list above but didn't as it really makes no sense. Also just because an official terminology exists does not mean an internal private terminology must be the same. The British army could use the term autocannon, Vickers does not have too. Finally Vickers could have more than one weapon in the works that qualifies as autocannon, the pom pom and an weapon derived from it say for tanks. The internal coding for those would be different even though they are both autocannons.

You do raise a very valid point but this is pretty much uncharted territory and short of contacting the pattern room or something I don't know how we could realistically get an accurate answer. This speculation is the best we can manage.
 
Is that in period documents or modern books/papers etc looking back?
Both. It just doesn't seem to be used as a common term in the UK, from my limited resources.

However, I'm going to throw something out there. The note was talking about .303 and ammunition quantity before the scribble in question..
Was (is?) a common abbreviation by engineers for machine M/c? Could he be talking about the Vickers K?
 
Both. It just doesn't seem to be used as a common term in the UK, from my limited resources.

However, I'm going to throw something out there. The note was talking about .303 and ammunition quantity before the scribble in question..
Was (is?) a common abbreviation by engineers for machine M/c? Could he be talking about the Vickers K?

If referring to the Vickers K why not just use the abbreviation k gun? It was designed in 35 so was around and known about.
 
10 July 1939. Newcastle-upon-Tyne. England.
10 July 1939. Newcastle-upon-Tyne. England.

The gun division of Vickers-Armstrong weren’t happy with what they’d been asked to do. There was so much work on, that looking at yet another adaptation of a gun was a pain. The Royal Navy had been looking to get as many of their old 12-pdr guns refurbished as possible for use on various second line ships. The 3-inch/45 20cwt QF HA gun had been designed before the Great War and there were 553 Mark I, 186 Mark II, 27 Mark III and 111 Mark IV in stock, and Vickers were working with the Royal Navy to get them fit for action.

The request from the tank division of the company was to look at the possibility of using this gun as the basis for a new tank gun was an unwelcome addition to the gun design teams’ work load. They knew that Woolwich was working on making a 3-inch howitzer to replace the QF 3.7-inch tank mortar used in the Close Support tanks, but that was a different proposition to what was being requested from Sir John Carden.

He wanted a dual-purpose tank gun that would have enough muzzle velocity to beat 3.5 inches (90mm) of armour with an anti-tank round, and an HE shell with a reasonable bursting charge. The team which had been given the task looked at various solutions, from the easy to overly-complex. But, with all the other work that was being done, just about every element of the company’s capacity was backed up already. Since the gun was a pre-Great War design, to bring it up to date, would mean that the design team would almost have to begin almost from scratch. A few shortcuts might be available, someone suggested using the new 25-pdr’s breech and recoil system and marry it to the 3-inch barrel. The problem was that the army was screaming out for as many 25-pounder guns as they could get their hands on. Any complications to the order for artillery guns would be frowned upon.

The only machinery which was standing relatively idle was the line for the Model 1931 75mm AA gun. This had been a particularly good seller: Romania and Denmark had bought a license to build it themselves. Belgium, the Netherlands, Lithuania, Finland, Turkey, Switzerland and China had all bought numbers of guns directly from Vickers. It hadn’t been taken up by any of the British armed forces, 75mm wasn’t a calibre it used much. Finland’s order had been rechambered to take their 76.2mm x 505R, so there was the equipment to make it a 3-inch gun if required, which would simplify sourcing ammunition.

The problem with transforming a gun designed as an anti-aircraft weapon and make it into a tank gun wasn’t insurmountable, but it wouldn’t be easy. First of all, the weight of the gun, just under three tons, would have to be stripped down as far as possible. The barrel length at 10 feet and seven inches, and the recoil length would either need to be reduced, otherwise the turret would look more at home on a ship than on a tank. To achieve this, and keep the muzzle velocity between 2000 and 2500 feet per second, to give it the penetration required, was all a difficult juggling act.

With the drawings of the Close Support Valiant turret to work with, the team had used the 3.7-inch howitzer’s fittings as the basis for attempting the forced marriage. It would take some doing, but they were able to send a report saying that this was the most feasible answer to the request. The draughtsmen’s opinion was that with the current size of the turret it would probably mean that there wouldn’t be room for three crewmen. If they were to progress to a working model, it would be necessary to get the go-ahead from the Board of Directors, to provide the funds to actually build the gun and then fit it to a turret to check for balance and all the other things that went into getting a tank gun working properly.
 
Nice! I like the way this is going. Well done representing the difficulties in getting a gun into service. We often stick guns on tanks in our discussions like it is a matter of dropping it in, so it is good to see the process actually illustrated.
 
So TTL’s Valentine will be like OTL’s Valentine, sacrificing a crew member to accommodate a buffer gun. The big difference is that the Valiant can take the 6 pounder so it’s relevant until at least mid war in Europe. I suspect the 75mm AA gun here will work, but the requirement for a 3 man turret crew will probably mean that Carden will end up designing a new tank for the bigger gun! Or by that time some one says if it’s an AA gun you want why not try the 3.7 inch!
 
So TTL’s Valentine will be like OTL’s Valentine, sacrificing a crew member to accommodate a buffer gun. The big difference is that the Valiant can take the 6 pounder so it’s relevant until at least mid war in Europe. I suspect the 75mm AA gun here will work, but the requirement for a 3 man turret crew will probably mean that Carden will end up designing a new tank for the bigger gun! Or by that time some one says if it’s an AA gun you want why not try the 3.7 inch!
Well the army is taking all the 3.7" AAs they can get their hands on, so that's not likely to be doable for a while yet. In Addition, a muzzle velocity of 2,000-2,500 fps sits the gun somewhere between the Americans' 75mm and 76mm guns in terms of power, which is a pretty decent weapon even into the late war. As a weapon for later marks of the Valiants it's a pretty good choice, but sticking a later-war gun on an at best mid-war tank is indeed going to require some compromises.

I do wonder though, could the weapon could be fitted in the Sherman.
 
Last edited:
Status
Not open for further replies.
Top