Alternative History Armoured Fighting Vehicles Part 4

Thanks muchly good Sir, much appreciated! ๐Ÿ‘๐ŸŽ‚๐Ÿ‘

Unfortunately, the decorative candles look more like a fire storm these days!! ๐Ÿ˜ณ๐Ÿ˜‰๐Ÿคฃ
happy belated bday!!

just light them outside and use them to barbecue lol
 
Well, I've no idea how old you are, but here's a cake that you can save until the appropriate date.

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Many happy returns​
 
What were the length and height of the S35 engine?

I'm wondering if a mid-1930s US gasoline engine, such as the Hall-Scott "400" truck/bus-market version of the "Invader" marine straight 6 (310 peak hp in 1937-38) or "Defender" marine 60ยฐ V-12 (about 1000 hp in a 1940 supercharged version), would have fit into the engine bay.

If so, then once the French British Purchasing Committee was started up, SOMUA might have bought powertrains from USA as a fast way to leapfrog their tank design toward greater mobility and an ability to carry the weight of more armor and armament.
 
What were the length and height of the S35 engine?

I'm wondering if a mid-1930s US gasoline engine, such as the Hall-Scott "400" truck/bus-market version of the "Invader" marine straight 6 (310 peak hp in 1937-38) or "Defender" marine 60ยฐ V-12 (about 1000 hp in a 1940 supercharged version), would have fit into the engine bay.

If so, then once the French British Purchasing Committee was started up, SOMUA might have bought powertrains from USA as a fast way to leapfrog their tank design toward greater mobility and an ability to carry the weight of more armor and armament.
No exact data, but a quick pixel measurement using the 120mm bore of the engine on its schematic would give roughly 1165mm length and 1045mm height without accessories.

France wasn't short of powerful tank engines however, especially not for the Somua series of which only 36/month were expected towards late 1940. The Hall Scott Defender would be far too big at nearly 2000 cu in ( 36L engine!), while the 17-18L Invader would probably be bigger (longer anyway given it has 6 cylinders in line) than the Somua V8. And at this size, France had better specialized tank engines well advanced in development in 1940 (a 350hp Renault straight-6). Even just lengthening the Somua V8 to a V12 (apparently suggested for a SOMUA G1 offering) would give an engine of comparable displacement to the Invader, but in a more efficient V12 configuration and with a bit more power. US engines could mostly help with numbers, but not really with performance at this point.
 
The Hall Scott Defender would be far too big at nearly 2000 cu in ( 36L engine!), while the 17-18L Invader would probably be bigger (longer anyway given it has 6 cylinders in line) than the Somua V8.
The Defender and Invader were ~ the same length; the Defender was created by joining two Invader cylinder banks to a common crankshaft housing in V-form, with of course a slight cylinder offset.
And at this size, France had better specialized tank engines well advanced in development in 1940 (a 350hp Renault straight-6).
The (possible) advantage of an engine like the Invader over an engine in "advanced development" would be that the former had a number of years of real world proof of ruggedness and absence of issues and problems, in relatively high numbers since it was primarily a commercial truck and bus engine, in addition to the related marine version. Hall-Scott as a significant US engine manufacturer for heavy over-the-highway trucks, marine uses, fire equipment, mining equipment, crawler tractors, engine-powered railcars and the like produced two orders of magnitude more engines than the expected SOMUA tank production.
Even just lengthening the Somua V8 to a V12 (apparently suggested for a SOMUA G1 offering) would give an engine of comparable displacement to the Invader, but in a more efficient V12 configuration and with a bit more power.
Yes, but again comparing a theoretical solution to a proven one in (moderate) volume production and heavy duty usage every day for many years.
US engines could mostly help with numbers, but not really with performance at this point.
Yes, not arguing that Hall-Scott's technology was advanced. Certainly it was not. But, their mid-to-late-1930s engines had impressive track records for ruggedness, durability, drivability and maintainability. Their higher torque and therefore much-flatter power curve, compared to an equal-displacement diesel or to most other spark-ignition engines of even 25% more displacement, made them easy to drive in challenging situations with less shifting, and allowed use of simpler transmissions without sacrificing performance.

As a side note, the Invader / 400 series also existed in well-proven flat versions, i.e. a straight six laying on its side, originally for use in underfloor mounts for snub-nosed, rear-engine buses. Such an engine configuration could be utilized to create a medium tank or assault gun that, while wider, could be much lower than the late-1930s norm. That wouldn't have been relevant to the S35, but could have been to a future project.
 
The Defender and Invader were ~ the same length; the Defender was created by joining two Invader cylinder banks to a common crankshaft housing in V-form, with of course a slight cylinder offset.

The (possible) advantage of an engine like the Invader over an engine in "advanced development" would be that the former had a number of years of real world proof of ruggedness and absence of issues and problems, in relatively high numbers since it was primarily a commercial truck and bus engine, in addition to the related marine version. Hall-Scott as a significant US engine manufacturer for heavy over-the-highway trucks, marine uses, fire equipment, mining equipment, crawler tractors, engine-powered railcars and the like produced two orders of magnitude more engines than the expected SOMUA tank production.

Yes, not arguing that Hall-Scott's technology was advanced. Certainly it was not. But, their mid-to-late-1930s engines had impressive track records for ruggedness, durability, drivability and maintainability. Their higher torque and therefore much-flatter power curve, compared to an equal-displacement diesel or to most other spark-ignition engines of even 25% more displacement, made them easy to drive in challenging situations with less shifting, and allowed use of simpler transmissions without sacrificing performance.

As a side note, the Invader / 400 series also existed in well-proven flat versions, i.e. a straight six laying on its side, originally for use in underfloor mounts for snub-nosed, rear-engine buses. Such an engine configuration could be utilized to create a medium tank or assault gun that, while wider, could be much lower than the late-1930s norm. That wouldn't have been relevant to the S35, but could have been to a future project.
Fair enough. On a second glance, the Defender is actually very modern for a commercial engine of the time, and it could have been a credible powerplant for one of the long-hull Shermans or preferably a US heavy tank, since as a boat engine, it runs constantly at its peak rpm of 2100. In a tank it would not always run at peak so you could up the maximum regime to get a bit beyond 600hp. And it would be overall a much more compact powerplant for the M6, which could allow sufficient size reduction to be viable even at around 600hp. Or you can keep the supercharged 900hp version. In the former case, the Defender appears as an engine of somewhat similar output to the late-war Chrysler A-65 project, but with a greater displacement and thus even better torque curve for heavy tanks.
 
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I have once again updated part 2 of photodump after a visit to the french archives: https://photos.app.goo.gl/5tnqr7DG7vhBrVRB9
Haul was less successful than I hoped, but still interesting.

The documents I aimed for this time mostly concerned Franco-British exchanges regarding tanks in 1939-40. The French sent a mission lead by engineer Dupuy in 1939 and 1940 to see British tanks. At this point in time, most new British tanks were prototypes or had barely entered production. The French didn't find much of interest other than the Christie suspension of the A13, and the Liberty engine was a very powerful engine by early war standards, matching the French Panhard autorail engine. They noted that the armor of the Matilda II didn't follow French principles for armor distribution in that the roof and floor were quite thin and the main armor had weakened zones because the angled parts were too thin when accounting for the real orientation of the tank in normal movement. The British testing grounds were thought to be insufficient to properly test mobility on difficult terrain, and the French may well have been right as Matilda II proved to have poor mobility on wet french ground in 1939, which delayed its complete deployment in the BEF.
They also got to study what appeared to be the very late A20 before the A22 specification was issued. The British used weird armor arrays where a thin cemented plate was stacked over a thin RHA plate (20mm over 20mm at the front, angled, 25 over 18mm spaced away from another 18mm RHA plate for the sides). The British methodology was flawed as only 2pdr AP was used, which was notoriously poor against cemented plates, and they did not compare the side array to a 60mm cemented plate of comparable weight. The British hoped to uprate the 350hp engine (Meadows or Bedford at this point) to 450hp for a tank which was expected to weight 45 tons, but was more likely to reach 50 tons. The French were very concerned about the future of the A20 and offered joint production of B1 tanks until a suitable replacement (French, British or unified) is obtained.

Overall, the French concluded that the British were behind them in certain technical areas (welded assemblies) and in mass production, and offered their expertise and their testing grounds at Vincennes, Satory and elsewhere for British tanks. Meanwhile, Sir Albert Stern of the TOG enquired the French in late 1939 to discuss with local specialists about the unification of both countries' designs, the development of a superheavy tank, and suitable AT weapons for tanks (the French having more designs available at this point). In any case the French still found the A13 and Matilda II to be interesting and encouraged mass production of both types. They found the Nuffield tank factory at Birmingham to be spacious and well-equipped, on par with the AMX factory at Issy-les-Moulineaux, and estimated that a production rate of 24 A13s per month could be obtained if the full capacity was used. At this point, the limit on the utilisation of this factory was allocation of material, the scale of British mobilization and requirements.

I also found a few reports from the various French tank inspectors from 1931 to 1938. The main takeaways are:
- continued development of diesel engines for tanks was recommended as early as 1931,
- the FCM 36's engine could be easily uprated from 90 to 100hp in 1938 with some tuning of the injection system as the cooling system could now cope with the extra power. The tank inspectors once again deplored that orders for tanks such as the D2 and FCM 36 were too small to incentivize mass production measures in the factories.
 
Would it technologically be possible to make the Zubr Class hovercraft skirtless just like this guys designs ?

No matter the opinion i would like to receive some info on which mathematical formulas to use regarding the design of such a thing.I am almost an engineer myself so im familiar with formulas math,coeficients and all that jazz and i can learn a few (or a lot) more if they help my theoretical project move further ahead
 
A hovercraft is kept elevated by the average pressure under it, applied over its bottom area, being greater than its weight when it's sitting on the ground and equal to its weight when it's reached movement-height.

A hovercraft without skirts is very inefficient at creating pressure under itself. With a super-light hovercraft with a relatively large area, sufficiently powerful blowers/fans may be able to create enough pressure. With a heavier hovercraft, the needed pressure is much greater. As the needed pressure increases, the inefficiency of a skirtless design becomes ever harder to overcome.

Calculate the gross area of your object. Given its weight, that gives you the needed pressure. If it's more than a fraction of a PSI, a skirtless design is going to be implausible.
 
A hovercraft is kept elevated by the average pressure under it, applied over its bottom area, being greater than its weight when it's sitting on the ground and equal to its weight when it's reached movement-height.

A hovercraft without skirts is very inefficient at creating pressure under itself. With a super-light hovercraft with a relatively large area, sufficiently powerful blowers/fans may be able to create enough pressure. With a heavier hovercraft, the needed pressure is much greater. As the needed pressure increases, the inefficiency of a skirtless design becomes ever harder to overcome.

Calculate the gross area of your object. Given its weight, that gives you the needed pressure. If it's more than a fraction of a PSI, a skirtless design is going to be implausible.
When you say a fraction what numbers are we talking about ? 0.something 0.0something 0.00000 something ?
Zubr class weights 555 tons fully loaded,its 57 meters long,25 meters wide and i say the hull is 3 meters tall so the gross area is 3342 square meters.When i say skirtless i dont mean open plenum i mean one that works with a peripheral jet.Open plenum is very inefficient
 

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This is off topic. Edit your existing post with a link to somewhere else where it's not, and I'll respond further.

I don't do PMs.
 
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This is off topic. Edit your existing post with a link to somewhere else where it's not, and I'll respond further.
The Zubr class is an armored personnel and heavy vehicles carrier.It is also armed to a great extend.What im proposing is a slight change to its propulsion mechanism.In this forum i really dont know which section is better suited for this question.This is an alternative armored vehicles thread after all.Unless by armored vehicles we mean something that has tracks and or wheels and nothing else.If that is true then send me a private message explaining in detail why such an idea that im proposing wont work
 
This is off topic. Edit your existing post with a link to somewhere else where it's not, and I'll respond further.

I don't do PMs.

Come reply here
 
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Uploaded one last haul for a while from the french archives: https://photos.app.goo.gl/5tnqr7DG7vhBrVRB9

I will probably stop until late this year due to the archives being reorganized so some docs become unavailable, but I should also now be able to visit the Chรขtellerault facility which has more stuff (esp blueprints) on AFVs.

Last Saturday, I found stuff related to the program started in 1939 for the tanks of 1941 and 1942, and more random stuff on infantry and AT weapons.
The most interesting bit this time was that we finally have some real characteristics and details on the Renault 16t infantry support tank or DAC 1, nicknamed "Billancourt's Somua" after the Renault factory of Billancourt. This was seen as a potential basis for the future infantry support tank which would replace the Renault R40 and Hotchkiss H39 series, and supplant the interim AMX 38 which met most but not all requirements of the 1939 program. A wooden mockup was being made in May of 1940 and a mild steel prototype could be expected 4 months later.

The DAC 1, as of the first half of 1940, seems essentially like a new, more efficient take on the Renault D2. It was built around a simple rolled-steel hull, the running gear designed by Renault to modernize existing R35s but with an additional pair of wheels and 3 pairs of "elastic" wheels (see picture of a R35 with it), the 180-200hp 4-cylinder derivative of B1 Bis' 6-cylinder engine, also used in the AMC 35, mounted transversely this time, and the APX 4 turret of the B1 Bis (or any of its planned replacements like the ARL 2). Armor basis was 60mm at the front, sides and rear, and 24mm on the floor and roof (the floor would have been further reinforced to 30mm in a version suitable to the Army, making the crew very safe to mines). Weight was an estimated 18-19 tonnes. The proposed 3-man crew (extra radioman) would have been reduced to 2 (voice radio only instead of telegraphy), saving more space and weight for even more fuel.
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Improved "9-wheel" Renault suspension

The DAC 1 stands out with a remarkably lower hull, 25cm lower than the D2 and 17cm lower than the Somua S35, which contributes greatly to its weight efficiency. Width and length are overall similar to D2. Thanks to these changes, the DAC 1 has more engine power than the D2, carries more fuel (400L instead of 350L), is faster at up to 30kph, is a smaller target, and is more heavily armored while being slightly lighter. Compared to the AMX 38, it is somewhat heavier and uses a less fuel efficient engine, but has a greater power to weight ratio, a roomier turret, a greater top speed (that has more to do with the gear ratios on teh transmission though), slightly better trench crossing capability, and heavier side armor. As AMX didn't want to modify the 38 further to compete, the 38 was to remain the interim tank for 1941 while the DAC was seen as more promising.
nKHbs6n.png
renault_d2_1936-72306.jpg

A DAC 1 drawing compared to the D2. Note the squatter hull, more central turret and the outlines for the transversely mounted engine and its rear transmission.

Though a considerable improvement over any infantry support tank, the D2 and even to some degree the Somua, the DAC has the major problem that it won't enter production anytime soon (not until the second half of 1941 at best), at which time the proliferation of 50mm guns and 50mm of armor on the German side and war experience would have most likely required such alterations to the French infantry tank program that they would have converged towards full-blown medium tanks (a 2-man turret with the long 47 would have been required at least to be relevant against 50mm-thick face hardened plates on Pz III and IV).

My one gripe with the DAC is that since most of the components existed as early as 1935, it would have been really nice if some ideas (lower hull and transverse AMC 35 engine) had been implemented back then. The choice of the old small-wheel suspension concept instead of the torsion bars and larger wheels seen on G1R and contemplated for R40/H39 modernizations is also unfortunate. But who knows what would have happened after June 1940 if France hadn't fallen and could continue the project...
On the other hand, who knows if the S35 couldn't have been made a little wider (to the level of the D2) and the V8 engine mounted transversely while the hull was lowered from the start...
 
(...) the proliferation of 50mm guns and 50mm of armor on the German side and war experience would have most likely required such alterations to the French infantry tank program that they would have converged towards full-blown medium tanks (a 2-man turret with the long 47 would have been required at least to be relevant against 50mm-thick face hardened plates on Pz III and IV).
As of 1940 the Germans thought that a short 75mm direct-fire gun, i.e. KwK 37 L/24, was the optimal main armament for infantry support AFVs, because smaller-caliber guns' HE shells were much less effective against infantry-battlefield targets. Arguably, the Germans were right. Perhaps the French would have had a similar realization before too much more time had passed.

If the French tank program had continued to evolve, it...much like the early-war German program, with the PzKpfW III and IV, plus the StuG III...might have featured a convergence toward a medium tank armor-powertrain-crewing approach, but a continued divergence of main weapons between tank-fighting and infantry-fighting versions of that otherwise-converged medium tank until the later time when tank-fighting main armament finally evolved to 75mm caliber.

France had at least two short 75mm cannons available...the hull gun from the B1 tank series, and the leftover 75mm Schneider guns from WWI, some of which were in use in casemate versions of the Renault FT. The former probably was much more expensive to build than the KwK 37, so not optimal as a tank weapon. The latter was very old and low-performance. But, either could have provided a starting point for prototypes and battlefield trials.
 
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