Author Topic: Churchill Tank  (Read 34503 times)

Offline tankmodeler

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Re: Churchill Tank
« Reply #150 on: January 12, 2015, 12:32:26 PM »
One gun I am surprised didn't have a longer barrel was the 95mm howitzer although there is probably a perfectly logical reason for the chosen length perhaps relating to the infantry version that didn't in the end enter service but I really don't know. 
I think the main reason is that it didn't need to. The CS guns were supposed to be line of sight, direct assault guns for laying down smoke or HE on targets immediately near the tanks, not for indirect artillery fire. Range and accuracy were not important in that role. Range was seldom more than several hundred yards and the accuracy was sufficient with the quite good HE or smoke rounds.

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Why then didn't they just increase the length of the barrel, removing the need for the counter weight and potentially improving accuracy and increasing muzzle velocity (note I did say potentially as I know there are other factors involved).
As they say, perfect is the enemy of good enough. The gun was good enough, why waste a second or a penny on making it better than was needed?

Paul

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Re: Churchill Tank
« Reply #151 on: January 12, 2015, 06:49:12 PM »

Now, if you are willing to add a full superstructure, kinda like a Priest, above the track-line, then the vehicle itself would easily support it, but there were better vehicles available at the time, so why bother. But it wouldn't be impossible. just clumsy and likely pretty ugly. :-)



That was more what I was thinking.  As for practicality…bah!


Something like this but using more space over the track guards for ammo storage and the like, which makes a lot of sense.



Love it!
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Offline Volkodav

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Re: Churchill Tank
« Reply #152 on: January 12, 2015, 10:35:19 PM »
One gun I am surprised didn't have a longer barrel was the 95mm howitzer although there is probably a perfectly logical reason for the chosen length perhaps relating to the infantry version that didn't in the end enter service but I really don't know. 
I think the main reason is that it didn't need to. The CS guns were supposed to be line of sight, direct assault guns for laying down smoke or HE on targets immediately near the tanks, not for indirect artillery fire. Range and accuracy were not important in that role. Range was seldom more than several hundred yards and the accuracy was sufficient with the quite good HE or smoke rounds.

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Why then didn't they just increase the length of the barrel, removing the need for the counter weight and potentially improving accuracy and increasing muzzle velocity (note I did say potentially as I know there are other factors involved).
As they say, perfect is the enemy of good enough. The gun was good enough, why waste a second or a penny on making it better than was needed?

Paul

While I agree with the sentiment of "perfect is the enemy of good enough", and have seen examples of it, there are also many examples of temporary, or band aid fixes becoming permanent in place of, sometimes highly affordable, or even cheaper, occasionally elegant, permanent solutions.  Apart from those you read about I have seen more than my fair share in over two decades working in engineering, both automotive and defence, some are perfectly good enough and don't need to be replaced while others can be quite troublesome but for one reason or another are never superceded. 

The 95mm howitzers barrel was a short length of the 3.7" AA barrel suggesting that it would not have been difficult to produce a slightly longer version of it, if for no other reason than to balance the weapon in the turret, compared to the added complexity and cost of fabricating and fitting the counter weight.  I recall reading that accuracy was a problem with the 95mm compared to the preceding 3"howitzer, from memory inadequate muzzle velocity was also mentioned but I am not as certain of this as the accuracy problem.  For all I know a longer barrel may have been trialed and / or rejected for perfectly valid reasons, it's just persisting with a counter weight instead of lengthening a barrel that was a shorter version of a longer barrel, especially when accuracy is a criticism of the weapon seems a bit odd to me.

Offline finsrin

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Re: Churchill Tank
« Reply #153 on: January 13, 2015, 05:45:40 AM »
Dang nice :)
Would not thought of this configuration.
Like it better than original Churchill.

Offline Rickshaw

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Re: Churchill Tank
« Reply #154 on: January 13, 2015, 11:18:45 AM »
Volkodav, like most high performance, high velocity guns, the 3.7in AA gun used multiple tubes to create what we call a "barrel".  These are held inside the externally visible, monoblock "barrel" and are designed, as they wear to be easily replaced.  They lock together to form one continuous tube which the shell travels down. The 95mm How. utilised one of these tubes, attached to, as you've already noted a 25 Pdr breech block on a 6 Pdr mount.  Ian Hogg IIRC described it as a "bit of a mongrel of a gun" with descent from many different breeds.   

The idea was to make a "cheap" infantry support gun (during the period when everybody thought that one of the keys to German successes on the battlefield was their provision of infantry guns to directly support their infantry in the attack.   The American 105mm Airborne How. also got pressed into this use by the US Army).  While this meant that it could be easy to upgrade the barrel length it also meant that it would rather defeat the concept of "cheap".  You'd have to make new barrels rather than utilising existing tubes.  You could, I suppose extend the barrel by adding two tubes instead of one and accept the limitations that would entail.

My question is why?  While the 95mm How's performance was pretty weak with a muzzle velocity of only 330 m/s (which must have made watching it a lot of fun 'cause you could easily have seen the shell in flight!) it was intended for HE firing (mainly) and used a HEAT round for AT use (which meant MV was immaterial to penetration).  It's MV was adequate for the role envisaged for it of direct fire support for infantry and armoured units.  Its shells were essentially the same weight as 25 Pdr rounds (although that idea fell by the wayside along the ways when a fixed round was adopted) so they carried about the same explosive filling as the then standard British field artillery round.   You'd get a higher MV with a longer tube but as the weapon wasn't intended for indirect fire there appears little point as the increased range wasn't required.

« Last Edit: January 13, 2015, 02:05:14 PM by Rickshaw »

Offline Volkodav

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Re: Churchill Tank
« Reply #155 on: January 13, 2015, 12:46:07 PM »
Based on the length of an existing barrel segment, now that makes sense.  I didn't realise the 3.7" was built up with a segmented, or even separate, barrel liner.  Anyway that would explain the barrel length and the resulting need for a counter weight, the whole thing just seems to make the 25pdr as trialed in the AC3 a more sensible approach as that weapon excelled in both direct and indirect fire.

On the 95mm not being intended for direct fire, while I realise CS tanks could be used for indirect fires, I was under the impression that the reason for their existence was to provide direct, high explosive, fire support against enemy emplacements (bunkers, pillboxes, MG nests etc.), AT guns and infantry, the sort of targets the 6pdr was not well equipped to engage.  Engaging such point targets requires a degree of accuracy that cannot be achieved with indirect fire, here increased velocity and a flatter trajectory would help but is not vital.

Offline Rickshaw

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Re: Churchill Tank
« Reply #156 on: January 13, 2015, 02:25:33 PM »
Based on the length of an existing barrel segment, now that makes sense.  I didn't realise the 3.7" was built up with a segmented, or even separate, barrel liner. 

Most modern guns are.  It makes them easier to manufacture and maintain.

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Anyway that would explain the barrel length and the resulting need for a counter weight, the whole thing just seems to make the 25pdr as trialed in the AC3 a more sensible approach as that weapon excelled in both direct and indirect fire.

The problem with using a tank mounted gun for indirect fire is that you really need a higher elevation than most turrets can handle for it to really be effective as a tactical use of such a weapon.  Without higher elevation angles, your range actually remains rather short to be really useful in such a role.  A 25 Pdr CS weapon would make sense but by the time that became obvious, the days of the 25 Pdr were starting to be numbered.  25 Pdr is a bit light for destructive shoots and was really intended for suppressive shoots.

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On the 95mm not being intended for direct fire, while I realise CS tanks could be used for indirect fires, I was under the impression that the reason for their existence was to provide direct, high explosive, fire support against enemy emplacements (bunkers, pillboxes, MG nests etc.), AT guns and infantry, the sort of targets the 6pdr was not well equipped to engage.  Engaging such point targets requires a degree of accuracy that cannot be achieved with indirect fire, here increased velocity and a flatter trajectory would help but is not vital.

It is also important because it just becomes a larger tank gun, so tank gunnery training can be used.  Artillery training is a different kettle of fish.  The role of British field artillery was to suppress the enemy, to prevent him from being able to shoot at the infantry while they advanced to the assault.  This was based on WWI practice, which had been so successful.  Having a close support weapon under the direct command of the assaulting commander means that he can direct and control it himself and not have to go through several layers of command in order to get a target destroyed.

Offline tankmodeler

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Re: Churchill Tank
« Reply #157 on: January 13, 2015, 11:45:02 PM »
On the 95mm not being intended for direct fire,
I think you may have misread Rickshaw's comment:
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You'd get a higher MV with a longer tube but as the weapon wasn't intended for indirect fire there appears little point as the increased range wasn't required.
The 95 was not intended for indirect fire for exactly the reasons you state. As for accuracy, accuracy is relative. Something that for an indirect shoot to 9 km is considered inaccurate may be quite accurate enough to put a round into or quite near an embrasure opening at 300-400m.

The muzzle velocity of the 95 was so low that almost everything would be lobbed anyway. Hitting the enemy house or bunker would be enough to surpress that fire from 400m and allow the infantry to close and knock it out. Putting a round into the hole is nice, but not normally required.

Paul

Offline Volkodav

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Re: Churchill Tank
« Reply #158 on: January 14, 2015, 02:21:03 AM »
Yes I did miss read his post, I thought it odd as CS tanks are quite clearly intended for direct fire.  Getting a round through a window may not have been necessary, but hitting a dug in AT gun or machinegun emplacement could be critical.  Interestingly modern CS and even demolition is provided by specific ammunition types fired by regular tanks.

Offline tankmodeler

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Re: Churchill Tank
« Reply #159 on: January 14, 2015, 02:48:50 AM »
Getting a round through a window may not have been necessary, but hitting a dug in AT gun or machinegun emplacement could be critical.
Indeed and the 95mm was quite good enough to hit a Pak 38 at 600m.

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Interestingly modern CS and even demolition is provided by specific ammunition types fired by regular tanks.
Modern tank HE rounds are generally either a HEAT round or a HESH round, AT rounds used in a duel purpose mode. Even if the explosive filling is less than an equivalent arty shell, it is generally good enough for infantry support, especially compared to the ww II 75mm round.

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Re: Churchill Tank
« Reply #160 on: January 14, 2015, 04:10:42 AM »
Moving away from Howitzer based systems, what about a self propelled weapon using a heavy mortar as its main weapon - say an Ordnance ML 4.2 inch Mortar mounted in a Churchill hull?  Or for something different, maybe have one of the large Soviet weapons put into production?
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Offline tankmodeler

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Re: Churchill Tank
« Reply #161 on: January 14, 2015, 04:28:43 AM »
Moving away from Howitzer based systems, what about a self propelled weapon using a heavy mortar as its main weapon
Make it a major change.

Put a large open topped casemate in the front of the tank. Have the driver either in a fold-away seat in front or in a permanent maount above the engine over the track guard. Place the baceplate on a reinforced floor and shortened support legs on a 360 ish deg turntable at trackguard height. Ammo stored in the corners of the casement or, if the baseplate is hieng enough off the floor of the chassis, under the level of the baseplate. Fold down side doors to permit rapid replenishment during sustained fire missions as opposed to using the ready rounds stored onboard.

Something vaguely like this?

Offline raafif

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Re: Churchill Tank
« Reply #162 on: January 14, 2015, 04:35:27 AM »
mortars are just a one-bang device :icon_nif: .... what you need (& that superstructure suggests it) is a bank of rockets ala LCT (R) C:-)

Offline tankmodeler

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Re: Churchill Tank
« Reply #163 on: January 14, 2015, 06:13:01 AM »
mortars are just a one-bang device :icon_nif: .... what you need (& that superstructure suggests it) is a bank of rockets ala LCT (R) C:-)

Oooo! Mount a Canadian "Land Mattress" (q.v) rocket rack on that puppy! Loads of bang thrown essentially randomly down range!

http://i661.photobucket.com/albums/uu336/8Hussar/Allied%20Artillery/Canadian%20Land%20Mattress%203%20Inch%20Rocket%20System/IMG_9262.jpg

Paul

Offline Rickshaw

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Re: Churchill Tank
« Reply #164 on: January 14, 2015, 08:21:18 AM »
The British 4.2in mortar wasn't a terribly good weapon being out ranged initially by the smaller 3in weapon.

The 4.2in was originally designed expressly for chemical use and only later pressed into service as a general heavy mortar.   It would be a bit of a small weapon for a vehicle the size of a Churchill.  Land mattress would be an interesting weapon to use although, it appeared rather late.  However, in either case would such vehicles really need as much armour as the Churchill carried?  Surely there are better uses for such a vehicle?

How about a Conga mine clearing system? Although carrying and pumping nitro-glycerine around next to me would not be something I'd particularly want to be doing (which is why putting it in an engineless Universal Carrier trailer was a much better idea IMHO).

Here is a trick question - what calibre was the British 3in infantry mortar?