Improve the Churchill tank.

Depends on what you want the tank to do.

There's a place for Scouting and Exploitation, where speed and smaller size is a bonus.
But small and light rules out many of the other things on that list.

But all should note, that the M3 Stuarts did well as 'Infantry Tanks' in the Pacific, given to poor distribution of Armor and AT Guns in the Japanese Army.
Besides the unnatural addictions to machine guns everywhere, the M3 had Radio, and peashooter 37mm had a very useful anti-personnel canister round.
About the only thing it couldn't do, was toss smoke, and lacked the telephone on the rear to talk with infantry

So a proper small US Infantry Tank early in the war, could have been an up armored M3 with an M8 75mm pack howitzer, with a proper top and TC cupola
Actually, all the US light tanks did rather badly in the Pacific. The M2 and M3 lights were found to be well, too light. They regularly impalled themselves on Palm stumps during the Island campaigns in US Marine service. In Australian service, they would found not to have sufficient "oomph" to get out of the swamps they often found themselves in (they were quite able to bog themselves). The Matilda was an excellent vehicle and was substituted for the US lights in Australian service. It had sufficient armour to withstand most Japanese AT weapons and sufficient power to get out of the swamps it often found itself in. The US Marines substituted the M4. The Australians, after trials opted for the Churchill, buying over 200 of them but they didn't arrive before the war ended. Churchill Mk VII was found to have better soft ground performance and wide enough tracks to cross most difficult ground. The M4 was basically a failure as far as the Australians were concerned. It's armour was too thin and it was underpowered.
 
1. The ground, to my mind, has never discussed the rationale behind the basic Churchill vehicle design from, a human ergonomics point of view. By any standard of functional man-machine interface the Churchill, in my judgement, like many a fighting machine on this forum, has not been addressed that way. Nor has its specifics, as virtues and deficiencies as to inside room to move about. hand things off among crew members (passing ammunition from the front carry boxes in the forward hull to the crew in the fighting compartment, as an example.), or the "turret monster", which is to say the basic inside "grab you and tear off an arm or leg" hazards inside the Churchill been shown as to be either a virtue or a hazard to the man-machine interface, nor has overall visibility, situational awareness, ease of gun feed or gun lay or engagement cycle time first round hit, been addressed in detail.

2. By 1. I mean the American understand this whole "ease of fightability of the system" concept. It is the British, whose reports I read, who do not seem to get the "Look, communicate, move, shoot, cycle". when it comes to anything remotely comparable to combined arms, even as a fighting unit. I even commented on that in some macros respects in posts; #16, #32, and #51 as to what I thought were the problems and the reasons why with the Churchill.

3. I am well aware of what system failure and success matrices are. If I am to judge by the Churchill's success, I would rate it as a decent mid-war British tank with a decent mechanical reliability and available for service upon contact with the enemy percentage rate, of about 80%. That is good. What I find substandard is what I have mentioned. It is not an easy tank to use as a fighting platform. It improves from Mark IV to Mark VII, but I flat out reject that it was ever as good as a Sherman as a tank.

4. Based on 3, how can I claim the Sherman was superior? Simple. The Sherman was several things the Churchill was not.
a. The Sherman was what the British would recognize as a "cruiser", or in American parlance "an exploitation tank"; that is a "cavalry or shock action" tank.
b. The Sherman mutated into just as many and as effective "funnies" as the Churchill and STILL could be used for its primary role as defined by a.
c. The Sherman chassis became the basis for tank destroyers, assault guns, self propelled artillery, kangaroos, armored engineer vehicles, Murphy knows how many field expedient hedgerow plows, bulldozers, mine clearers, and expedient engineer vehicles while still be able to flame throw, shoot and crunch stuff under its treads, depending on the Sherman.
d. The Churchill because of the way it was built and was intended to be used could be a "funny" but it lost its primary purpose in the process. It could not "tank" after it became a mine clearing vehicle or a wall breacher as easily as a Sherman. It was never intended to do so.

e. And besides, when the British tried for an early war replacement for a "main battle tank" or "universal" which they began to recognize as a tank role, that is what the Sherman defacto became, This actually is what the British army wanted... midwar.


f. They wanted a main battle tank. . a cruiser. Like the Sherman. Not the Churchill.



g. The point I made about the Black Prince was that it was an example of British tank designers being not clued in as to what the tank was supposed to do. It was in effect the British answer to the German Tiger I and it made about as little sense function wise.



h. For an infantry tank, that is close support of infantry, the Churchill Mark I to IV as a direct support platform could outclimb and it could cross terrain a Sherman tank could not. this is true. As a part of the British combined arms drill, that is look, understand, cooperate with artillery, infantry and airpower in the total matrix, no way in Murphy's hell, was it as good as a Sherman. Not even the Mark VII was as good in the ergo as to the situational awareness and communications department; and it sure was never as good as an overall expendable individual fighting platform. The Churchill fulfilled an infantry close assault specialist niche, and that it did fairly well, but the Wallies could have won without it. Not so without the Sherman tank. The Sherman disappears and something like it (T-23/M25 or even the M7 for example), has to replace it in the hole it leaves behind. A main battle tank (cruiser) has to be there for the Wallies, as the T-34 was for the Russians. Tanks are attritional inside the combined arms matrix. Survive long enough to do its job across the entire battle matrix.



i. Zu spät ist so gut wie nie. (Too late is almost never.)



j. The Americans understood infantry tanks and cavalry tanks. They legislated it into their national law in the 1920 National Defense Act. They even incompetently tried to build to it with a whole series tanks that were optimized for cavalry exploitation and infantry close assault roles. The M3 was the scout, the M6 was the American abortion that could be compared to the Churchill in mission role, and the M4 was the American "cruiser". Guess which two worked well?



k. Hard to say, that the Churchill was a result of enemy action. The British army did even not want it. They tried to KILL it in development.

l. One last comment on British attention to human ergonomics...


j. The British did understand ergonomics. (At least the end-users were aware when they tested the things and wrote up all the fail issues.). However when war happens and one needs a tank to do a job: one sends out a Grant/Lee or a Churchill Mark I to IV, and then fixes the bodges later. (Sherman and or Churchill VII).

McP.
You are applying 20/20 hindsight. That will never fail to find fault with what the British did. They however didn't have that ability, they just did what they thought was the right thing to do at the time. They just muddled through.
 
You are applying 20/20 hindsight. That will never fail to find fault with what the British did. They however didn't have that ability, they just did what they thought was the right thing to do at the time. They just muddled through.
Well; if you mean by 2020 hindsight US and British army WWII reports and the user comments therein such as the load path to the M3 90 mm gun was "unacceptable" in the T-26 tank unless and until the commander's position was moved back and right out out of the loader's way, for example, then I am guilty of 2020 hindsight.

McP
 
The M4 was basically a failure as far as the Australians were concerned. It's armour was too thin and it was underpowered.
The only country to think that, given that the A12 had two 410 cubic inch, 87hp@2000rpm bus engines for a 25 ton tank with 16.2 psi ground pressure, if you want to talk about underpowered.

Soviets found them worthless for their boggy conditions.
1596955038986.png

But hey, Oz seemed to like those overengineered tanks
 
See second previous comment. I will say that this problem of branch politics and service tradition still carries forward somewhat into France 1944 in that the incompetent RAF did not get with the program this time; ignoring Desert Air Force close air support lessons learned!
Really? 83 Group would disagree.
 
Re the Australians and Matildas. The Australians were there. They made a choice based upon being there. We play Top Trumps with book information. I go with the Australians. It was clearly right for them. The New Zealanders went for the Valentine.

I suspect that they got diesel low rev torque plus medium tank armour in a light tank size. Shermans are huge towering things by comparison. The Churchill is a big version with a proper QF75mm gun. I am too idle to look it up but I think that the Matilda, Valentine and Churchill could do zero radius turns whilst the M4 Medium could not. A very handy skill in jungle.
 
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The only country to think that, given that the A12 had two 410 cubic inch, 87hp@2000rpm bus engines for a 25 ton tank with 16.2 psi ground pressure, if you want to talk about underpowered.
What the RAAC wanted was a tank that was small enough with sufficient armour to fit on their landing barges. They got that with the Tilly. They got the right size but with insufficient armour in the M3. The Tilly stayed in service until 1954. It was the right tank for the circumstances. They developed their own 2 Pounder HE round for the gun as well. It was based fused, which ensured that it would penetrate the Japanese bunkers before exploding, unlike the British nose fused round. The Churchill was determined to be a good replacement for the Tilly. It had more than sufficient armour and more torque than anything else to get it out of swamps. Torque, not horsepower is what makes tanks mobile.
 
Matilda, Valentine and Churchill could do zero radius turns whilst the M4 Medium could not. A very handy skill in jungle.
Only the Churchill had the Merritt-Brown triple differential that allowed neutral steer to pivot in place of the Meadows crash gearbox with Clutch and Brake differential steering in the Valentine or Wilson gearbox with Rackham Steering clutches in the Matilda. The T-34 and early war Mk i and Mk II German tanks used clutch and brake steering as well. Most other nations had changed to geared steering systems

Clutch and Brake was non-regenerative, meaning power is lost in a turn. Controlled differential, like the M4 Cletrac or the Merritt-Brown, was fully regenerative losing no power in a turn.

The difference between Cletrac and Merritt-Brown is the Cletrac had a fixed ratio for a turn, while the other was fully variable. Cletrac was simpler and more robust, the reason it's still used in Bulldozers.
 
Really? 83 Group would disagree.
Narrative.

Assembling the Allied Tactical Air Forces
As OVERLORD embarked upon its preparatory phase, tactical air power increasingly came into play. Two great tactical air forces existed to support the ground forces in the invasion--the AAF's Ninth Air Force and the RAF's Second Tactical Air Force. Both were under the overall command of Royal Air Force Air Chief Marshal Sir Trafford Leigh-Mallory. In addition, of course, Eisenhower and his ground commanders could call upon strategic aviation as required, in the form of the AAF's Eighth Air Force and Great Britain's Bomber Command.
In June 1944 the Ninth Air Force consisted of several commands, including the IX Fighter Command. The IX Fighter Command in turn spawned two Tactical Air Commands, the IX TAC and the XIX TAC. IX TAC had three fighter wings, and the XIX TAC had two. Each of these fighter wings contained at least three-and usually four-fighter groups, a group typically consisting of three fighter squadrons. Of the two, IX TAC was the "heavy"; it could muster no less than eleven fighter groups, while the XIX TAC could muster seven. From late 1943 to early 1944, IX Fighter Command had served primarily as a training headquarters, under the command of Brig. Gen. Elwood Quesada. Eventually Quesada assumed command of the IX TAC, and Brig. Gen. Otto P. "Opie" Weyland took

--4--


over XIX TAC. No in-theater formalized structure linked the Ninth and its subordinate commands directly to specific land forces units, though there was a general understanding that the IX TAC would support the First Army, and the XIX TAC would support Lt. Gen. George Patton's Third Army once the Third became operational in France nearly two months after D-Day. Eventually, on August 1, 1944, when both Patton's Third Army and Bradley's 12th Army Group became operational, this arrangement was formalized.
On the British side, the RAF's Second Tactical Air Force (2 TAF) had grown out of initiatives in mid-1943 to structure a "Composite Group" to support the invasion of Europe. It had risen from the ashes of the moribund and never-satisfactory Army Cooperation Command. In January 1944, Air Marshal Sir Arthur Coningham took command of 2 TAF, and two months later he assumed additional duties as commander of the Advanced Allied Expeditionary Air Force (AAEAF). Ironically, at this critical point, two serious command problems arose. Relationships among the RAF commanders, particularly Coningham, Leigh-Mallory, and Arthur Tedder (Deputy Supreme Commander for OVERLORD) were strained at best. Much more serious was the breakdown between the RAF commanders and 21st Army Group Commander, Field Marshal Sir Bernard L. Montgomery, who also wore an additional hat as commander of Allied ground forces during the invasion.
While fighting Rommel in the Western desert, Montgomery had enthusiastically supported air action in the Mediterranean and accepted whole-heartedly Coningham's thoughts on air support. Ironically, Montgomery and the RAF now came to disagree over the relationship between the air and the land commander. Montgomery paid lip service to the concept of independent air action, but his actions in early 1944 clearly indicate that he considered his equals in the RAF merely advisers. For their part, Coningham and Tedder nursed grudges going back to the plodding advance after second El Alamein and Montgomery's notorious slowness during the pursuit of Rommel's retreating forces.
For the airmen, the critical question in OVERLORD was how rapidly Montgomery would advance to seize airfields so Allied tactical air forces would not have to operate across the Channel, from bases in England. In fact, this issue turned out to be far less important than originally thought. Bases were quickly hacked out of the Normandy terrain, often only a few thousand yards from opposing German forces. Montgomery's planned advance from the beachhead (which the airmen considered too slow) turned out to be

--5--



SHAEF Organization Chart

--6--


instead over-optimistic; the actual advance was even slower. Given this, Allied air power in Normandy proved all important. As historian John Terraine has noted:

History insists that the last word, in regard to the Battle of Normandy, must be that the quarrels did not, finally, matter: Allied air power was so overwhelming that the defeat of Allied intentions on the ground never threatened disaster, only delay, and that only in the early stages, well compensated later. But let us be quite clear about it: what made the ultimate victory possible was crushing air power.
IOW... incompetent. As in success in spite of, not because of. I tend to think Montgomery had those two yahoos (Leigh Mallory and Tedder) pegged about right. Coyningham is another fish kettle. He did well. Western Desert, you know?

McP.
 
Torque, not horsepower is what makes tanks mobile.
I have been very unsuccessful in finding out how much actual torque the AEC produced. From Calculation, that should be 228.5 ft-lbs for each motor at max rpms, and probably
250ft-lbs best at lower rpms

That's not a lot. the GM 6-71 diesel, similar in displacement, had twice as much torque and higher HP. Advantage of being a two-stroke diesel with a blower, which is why the Valentine did well with a single 6-71, and M4A2 with two of them.

The weight of the later 95hp Leland E170 twin mount per Soviet Sources have at 1200kg, and the Valentine single 165 hp 6-71 of 725kg, and M4A2 double install of 6-71 at 2040kg
 
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What the RAAC wanted was a tank that was small enough with sufficient armour to fit on their landing barges
Exactly. But there was an additional problem.

After crossing the start line at 0700 hours, the tanks moved at an infantry pace, with the infantry moving beside or close behind. This work was not what the Stuarts were designed for and continuous slipping of clutches and low engine revs caused the drivers much trouble. Where the tanks encountered Japanese bunkers, these were attacked by the tanks at point blank range and finished off by the infantry throwing in grenades. The left flank company, having no supporting armour, faired badly and suffered many casualties. As Captain Whitehead had left his troop leaders to run their own battle, he was at a loose end until the request for tank support came from the left flank company. Turning west, he came up against three strongpoints. The southern bunker was despatched with five rounds and turning to take on the next, the gunner‘s sights fogged over. Whitehead had his face pressed against one of the turret vision slits when a Japanese soldier leaped onto the tank and fired his rifle against the slit. Severely wounded by shrapnel from the armour and the bullet, Whitehead fell into the tank. As the tank turned to evacuate him, the gunner fired a 37mm round at another Japanese firing from behind a tree.

After crossing the start line at 0700 hours, the tanks moved at an infantry pace, with the infantry moving beside or close behind. This work was not what the Stuarts were designed for and continuous slipping of clutches and low engine revs caused the drivers much trouble. Where the tanks encountered Japanese bunkers, these were attacked by the tanks at point blank range and finished off by the infantry throwing in grenades. The left flank company, having no supporting armour, faired badly and suffered many casualties. As Captain Whitehead had left his troop leaders to run their own battle, he was at a loose end until the request for tank support came from the left flank company. Turning west, he came up against three strongpoints. The southern bunker was despatched with five rounds and turning to take on the next, the gunner‘s sights fogged over. Whitehead had his face pressed against one of the turret vision slits when a Japanese soldier leaped onto the tank and fired his rifle against the slit. Severely wounded by shrapnel from the armour and the bullet, Whitehead fell into the tank. As the tank turned to evacuate him, the gunner fired a 37mm round at another Japanese firing from behind a tree.
One gets the idea? The M3 Stuart was a "reconnaissance tank", a scout vehicle being used as a classic British style "infantry tank". Of course the Stuart was not going to work well. The Matilda II was an infantry tank designed for close assault to fit the British method of methodical battle.

It is no knock on either tank to suggest that the Australians used the wrong tank, the wrong way at Buna and Goa, but that was what they had, what they could lift and so the Stuart was used. Matilda II shows up and the Australians have a small tank with a thick hide and seemingly a better fit for British style combined arms. If it had been an M7 it might have fared as well as a Matilda II...

But one will never know, because the M7 was not built.
 
The M3 was all that was available at the time. It was desperate times. They used what they had and it was inadequate. No arguments there but the Tilly, once it became available for use in New Guinea and the Islands was a perfect fit for what the RAAC wanted it for. As much as you might argue this or that might have been better, they weren't available, at the time or in that place. So, the RAAC muddled through. The M3 was proven too light and too unreliable for what was asked of it. As you note, it doesn't make it a bad vehicle, it just made it the wrong vehicle.
 
The M3 was all that was available at the time. It was desperate times. They used what they had and it was inadequate. No arguments there but the Tilly, once it became available for use in New Guinea and the Islands was a perfect fit for what the RAAC wanted it for. As much as you might argue this or that might have been better, they weren't available, at the time or in that place. So, the RAAC muddled through. The M3 was proven too light and too unreliable for what was asked of it. As you note, it doesn't make it a bad vehicle, it just made it the wrong vehicle.
Kind of missed the point I aimed at. My fault. It is that if the Stuart had been built more like a Matilda II, it would have been more successful as an "infantry tank". Take a good hard look at the M7 and ask oneself why was it not built?


Source...
M7 Light Tank Walk Around Page 1

Too Heavy for a Light, too Light for a Medium

The trial stages of the M7 were where the tank's biggest issues came to light. It was soon apparent that this vehicle far surpassed the required weight limit even further than originally thought, as fully loaded, the tank came to weigh in at 28 to 29 tons. It was soon found this problem was caused by a number of parts being cast thicker than specified. The M7 barely scraped into the Medium Tank weight class, however, weighing a base tonnage of just 27. The M4, for instance, weighed up to to 38 tons.

Further trials with the M7 soon showed it to be somewhat ineffectual. The tank had weaker armor than the M4 Sherman, at just 64 mm (2.52 in), compared to the Sherman's 75 mm (2.95 in). Also, it granted nothing in the way of greater anti-armor firepower and had only a partial advantage in speed and maneuverability. The M7 Medium Tank project was canceled due to these issues as soon as the trials had finished. The heads of the American Armored Forces instead opted to stick with their battle-hardened M4 Mediums and M5 Lights. Both of which would serve until the end of the war.

An article by Mark Nash
From Tank Encyclopedia online.

M7 Medium Tank Specifications (finalised design)
Dimensions (L-W-H)17'2'' x 9'4'' x 7'9'' 5.23 x 2.84 x 2.36 m
Total weight27 tons
Crew5 (driver, co-driver/bow gunner, gunner, loader, commander,)
PropulsionContinental R975 C1; 9 cylinder, 4 cycle, radial gasoline 350 hp
Speed (road)30 mph (48 km/h)
Armament75 mm (2.95 in) Tank Gun M3 2x 30 cal. (7.62 mm) machine guns
Armor13–64 mm (0.51–2.52 in)
 
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Take a good hard look at the M7 and ask oneself why was it not built?
Delays.
I go into this a bit at https://www.alternatehistory.com/forum/threads/name-five-plausible-things-the-us-can-do-to-better-enter-wwii.491969/post-20759611

Wasn't the every shifting design, as much as the getting the authorization after much of the USA's tooling and raw material had already been assigned to other projects with higher War Production Board priorities, had to wait for P&W and Bridgeport to fill other orders before they could get Mills and Lathes delivered.

So you had a vertically integrated Tank Arsenal, with the capacity to build thousand of AFVs a year, do final assembly before shipping, stuff like fitting British or Soviet specific gear for L-L(Radios, sandshields, etc), and only built seven tanks from start.

Having 12mm less armor on the gun mantlet than an M4A1(only location with 76mm armor, near everything else was 50mm) is hardly a make or break deal for a tank that was 5 tons lighter.

Much smaller profile, too


Some innovations,
1596983072396.png

later used with the M18 TD, rails to slide out engine and final drive/transmission- both able to beremoved and swapped in 20 minutes, getting close to the 'power egg'
like the M18, had a Spicer torque converter in place of a clutch, and low drive shaft
1596983348440.png
 
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Delays.
I go into this a bit at https://www.alternatehistory.com/forum/threads/name-five-plausible-things-the-us-can-do-to-better-enter-wwii.491969/post-20759611

Wasn't the every shifting design, as much as the getting the authorization after much of the USA's tooling and raw material had already been assigned to other projects with higher War Production Board priorities, had to wait for P&W and Bridgeport to fill other orders before they could get Mills and Lathes delivered.

So you had a vertically integrated Tank Arsenal, with the capacity to build thousand of AFVs a year, do final assembly before shipping, stuff like fitting British or Soviet specific gear for L-L(Radios, sandshields, etc), and only built seven tanks from start.

Having 12mm less armor on the gun mantlet than an M4A1(only location with 76mm armor, near everything else was 50mm) is hardly a make or break deal for a tank that was 5 tons lighter.
Take a good perusal of the walkaround photos at the citation provided and ask how 5 men do in 30% less internal working human volume than a Sherman, while trying to do a Sherman's job as a recon tank.

The M-24 Chaffee starts to make sense?
 
Take a good perusal of the walkaround photos at the citation provided and ask how 5 men do in 30% less internal working human volume than a Sherman, while trying to do a Sherman's job as a recon tank.

The M-24 Chaffee starts to make sense?
M7M24
Crew5, 3 man turret4 or 5
Hull Length206"198"
Width112"118"
Height93"109"(with AA MG)
Ground Clearance16"18"
Fire Height/Bore Axis77 "73"
Turret Ring diameter64"60"
Ground Pressure10.7 psi11.3 psi
Weight, loaded53,95040,500 lbs
Power to weight13 hp/ton10.9 hp/ton
Ammo71 rounds48 rounds
Fuel138 gallons110 gallons

1596986785584.png
1596987011262.png

So M24 is even smaller, less volume to the M7, as needed a taller hull for the Radial, less protection, and M7available to the troops a year and a half sooner
Beats using a M3A3 or M5 for Recon
 

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Was that because of the tracks? I was under the impression that was an intelligence failing, in picking the wrong beaches. Considering how famous the Churchill’s climbing ability is, it seems unlikely any other tank would have done better.
No tank likes shingle beaches!
 
Well, that's not very accurate.

You originally said:

The most effective support from the DAF was under Broadhurst, who commanded 83 Group and was unlikely have forgotten the lessons learned (even if it's not clear what you think those lessons were :)).
I know what I wrote. I also know what I quoted from Hyperwar. Please compare and reach your own conclusions. My opinion is not written in stone. But I trust the USAAF narrative more than my opinion and they said what I said.

McP.
 
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M7M24
Crew5, 3 man turret4 or 5
Hull Length206"198"
Width112"118"
Height93"109"(with AA MG)
Ground Clearance16"18"
Fire Height/Bore Axis77 "73"
Turret Ring diameter64"60"
Ground Pressure10.7 psi11.3 psi
Weight, loaded53,95040,500 lbs
Power to weight13 hp/ton10.9 hp/ton
Ammo71 rounds48 rounds
Fuel138 gallons110 gallons

View attachment 573731View attachment 573736
So M24 is even smaller, less volume to the M7, as needed a taller hull for the Radial, less protection, and M7available to the troops a year and a half sooner
Beats using a M3A3 or M5 for Recon
I will allow Nicholas Moran to make my rebuttal.


Note how the internal volume is distributed.
 
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