Alternative German tanks & AFVs (1 Viewer)

[tomo pauk]

How much the Germans have 'slept' on the captured 47mm stuff. Once outfitted with the cored ammo, the Czech 47mm ATG used 642g of propellant, the French 47mm used 560g of propellant, while the short 50mm used 557 g of propellant.
(sorry for the lousy quality of the Czech/German PzGr40 cartridge)



Respective shot weights were 800g for the Czech gun, 825g for the French gun, and 900g for the 5cm gun.

 

[Elan Vital]

If one had made no diesel engine worth speaking about, and the fuel flow was more or less unproblematic, then keeping it with the gasoline-powered tanks was a no brainer

Aside from Russia the other 'major' uses of diesel engines in tanks were the Japanese and Italians.
The Italians tended to bounce back and forth. They wanted diesels but an useable diesel was not always available and they resorted to petrol engines while they sorted out higher powered diesels. How good the 1943 higher powered diesels were may never be known. Not many were built and conditions were not good.
Japanese had started making diesels in very early 30s but getting powerful diesels may have taken a while. Powerful is relative. Japanese were using a 21.7 liter air cooled diesel of 170hp in 1941 in their 15ton (roughly) medium tank at that time. They got 240hp from the engine later (1943?)
The late war Czech diesel used the later 8 wheeled armored cars was 14.8liters and gave 220hp and was air cooled.
In the late 30s Diesels may not have given the power to weight ratios or power to volume ratios that were wanted.
Soviet V2 was powerful, it was also large, and it may not have been very long lived. The Soviets may have accepted the trade-offs. Other countries may not have.

The Japanese appear to have made the worst tank diesels from a power-to-displacement standpoint. The 21.7 L engine on the Chi-Ha had been rushed (barely tested) before approval. The Type 100 employed on the Chi-He and Chi-Nu had got the time to be better designed, hence the 240 hp (1940).

The Type 4 on the Chi-To developped from 1942-43 onwards initially made 412 hp out of 37.7 L and 500 hp when supercharged, which was still mediocre compared to V-2 analogues, but more or less acceptable.

Italian diesels started worse than even some commercial British ones (save for the more convenient V8 form factor). Some were derived into petrol versions in emergency but as they were not built for this fuel from the start, they were not very efficient (as opposed to the gasoline engine made for the Sahariano tank which was efficient). The SPA 242 in the P26/40 did do 330 hp out of 24L which was respectable, and was to be pushed to 430 or 460 hp in the SPA 342 or 343 mooted for faster versions of the tank, but killed by Italy's fall. There was a large 700 hp diesel in development, but displacement is unknown.

Daimler-Benz set for itself the target of getting a very modern and efficient diesel tank engine in 1938 which led to the MB 809. However, they trended towards making a smaller engine rather than keeping displacement the same and increasing power: they went from 400 hp at 24 L to 360 hp at 17.5 L and 300 hp at 14.8 L. The marine MB 507/517 family mooted for the Maus and VK-3002 (DB (800 hp naturally aspirated and 1200 supercharged at around 42-44 L) was also efficient, if a bit large. MAN also worked on a diesel before 1942 but just like the 809, couldn't be upscaled to meet the needs of the VK-3002 program. But from 1942 onwards, almost all new engines in development in Germany were diesels, with only Maybach continuing development of the existing gasoline engines. Even then, they also moved to diesels derived from the HL 230 family towards the end of the war. The issue here was not performance, but simply that it was too late and that the engine couldn't be expected to enter production until late 1945/46.

Britain employed commercial diesels early in teh war which were on the inefficient side but still better than Japanese and Italian early models. Work on (allegedly purpose-made) tank diesels happened some time around 1940-41 but they were made for no more than 350 hp, so unsuitable for the needs of the new tank programs by then. Harry Ricardo briefly worked on a family of H16/24 and I6/8 diesels from 1939 onwards which were quite efficient and could deliver up to 560 hp unsupercharged and 720 supercharged (not even mentionning TOG's Paxman Ricardo), but Ricardo was too busy on aircraft engines and the Army focused more on the Meteor.

America was very unlucky as the Guiberson radials tried before the war were fundamentally flawed and Buda/Guiberson was not actually interested enough to redesign them accordingly. The Detroit Diesels were good but it was too late to expand production enough to make a real surplus, considering these engines were in very high demand for naval assets. Caterpillar diesel radials and half-radials were too late. George H Rarey, an officer involved in tanks in the interwar period, recommended diesels (albeit with a rather ambitious desire for 5 hp per pound of engine weight), especially in flat and radial forms. Ironically, the target power ouputs (25-30 hp per ton on the US interwar tanks) translated to 375-450 hp for the medium tank and 187.5-225 hp for the light tank, which was right in the class needed for the main US tanks fielded during the war.

French tank inspectors were quite interested in diesels ever since 1929 or so, with some in development for Renault FT and FCM 2C modernizations. The B2, B3 battle tanks and BB fortress tank all employed dedicated tank diesels, half or more of the light tank entries in 1933-35 used diesels (but were not adopted for unrelated reasons), the ARL and AMX 45t fortress tanks used diesels (commercial and dedicated alike), and AMX went with only diesels ever since it started working on new tanks. Dedicated engines (instead of commercial/aircraft engines until then) for 65 octane gasoline remained the norm for the new developments of 1939-40 - as by this point, mass adoption of diesels in a sea of gasoline engines would face an uphill struggle just like in the US.

The USSR was unique in that
- it was used to high output tank engines so the V-2 was suitable for the entire war, while even dedicated engines designed elsewhere could well have been too small and weak to serve the entire war (in tanks at least)
- V-2 development started all the way back to 1932, so that the engine was already well-developped (if a little short-lived still) when Barbarossa happened
- the state of the Soviet gasoline process industry and civilian road economy was such that road gasoline engines were not particularly important, unlike certain Western countries.

Even then, Harry Ricardo noted that before WW2, the British had moved on to diesel engines for heavy trucks, such that there weren't many high power gasoline engines in use.

So other than the Soviets, most belligerents had not made a serious dieselization effort (with dedicated, high output designs) until they were already too deep in WW2 to transition.

 

[Shortround6]

I would note that most (all?) of the Japanese diesels were air-cooled which may affect the power per unit of displacement.
The V-1790 diesel used in the M-60 tank in the late 50s was 750hp from 29.3 liters. Based off the 810hp gasoline version of the engine (which had been cut in 1/2 for a 500hp 6 cylinder engine in the M-41 tank).
Basically in the 1930s-40s you were trading engine size/weight for fuel efficiency when you swapped diesel for gasoline engines. M3 Grant gained about 3000lbs when they stuck in the twin diesels, there were other changes but that was the main change in weight.
Now what is not figured in here is the overhaul life. A lot of these heavy duty engines in later years were rated at different power levels for different applications. Like stationary powerplant, marine, over the road, emergency vehicle and/or military use. There can be further categories or overlaps. Are you going to use that Detroit Diesel 8V-71 in a fishing trawler for days at a time or a ferry boat or a sportfishing yacht a few week-ends a month? All Marine use but different duty cycles.

A Chieftain video says the early T-34 engines were good for about 100hrs before overhaul. Where he got that from I don't know but that is probably a different expectation than AEC or Leyland had for their bus engines. Granted the Buses probably didn't weigh 15 tons or more and rarely drove in dirt or sand for very long in 1-2nd gear.

 

[Shortround6]

In hindsight and with swapping around of manufacturing capability the Pz II should have been tossed in the rubbish bin in early 1941. Any attempts to keep it in production should have been ruthlessly squashed.
The Pz 38(t) was a superior platform and needed less mucking about with (engine was 25% bigger for one thing).

By the time they got the extended chassis MK II to hold the 15cm Infantry gun they were up to 16 tons, even the V-8 engine was overloaded and at 16 tons they should have been looking at the MK III for any further improvements.
The 15cm inf gun was put into the Pz 38 (t) chassis with a lot less grunting, groaning, and straining and while not ideal, it worked about as well as the Wespe. With expanded manufacturing capacity the Pz 38(t) could have replaces the Wespe and most of the Pz II 75mm AT guns.

 

[Reluctant Poster]

The Japanese appear to have made the worst tank diesels from a power-to-displacement standpoint. The 21.7 L engine on the Chi-Ha had been rushed (barely tested) before approval. The Type 100 employed on the Chi-He and Chi-Nu had got the time to be better designed, hence the 240 hp (1940).

The Type 4 on the Chi-To developped from 1942-43 onwards initially made 412 hp out of 37.7 L and 500 hp when supercharged, which was still mediocre compared to V-2 analogues, but more or less acceptable.

Italian diesels started worse than even some commercial British ones (save for the more convenient V8 form factor). Some were derived into petrol versions in emergency but as they were not built for this fuel from the start, they were not very efficient (as opposed to the gasoline engine made for the Sahariano tank which was efficient). The SPA 242 in the P26/40 did do 330 hp out of 24L which was respectable, and was to be pushed to 430 or 460 hp in the SPA 342 or 343 mooted for faster versions of the tank, but killed by Italy's fall. There was a large 700 hp diesel in development, but displacement is unknown.

Daimler-Benz set for itself the target of getting a very modern and efficient diesel tank engine in 1938 which led to the MB 809. However, they trended towards making a smaller engine rather than keeping displacement the same and increasing power: they went from 400 hp at 24 L to 360 hp at 17.5 L and 300 hp at 14.8 L. The marine MB 507/517 family mooted for the Maus and VK-3002 (DB (800 hp naturally aspirated and 1200 supercharged at around 42-44 L) was also efficient, if a bit large. MAN also worked on a diesel before 1942 but just like the 809, couldn't be upscaled to meet the needs of the VK-3002 program. But from 1942 onwards, almost all new engines in development in Germany were diesels, with only Maybach continuing development of the existing gasoline engines. Even then, they also moved to diesels derived from the HL 230 family towards the end of the war. The issue here was not performance, but simply that it was too late and that the engine couldn't be expected to enter production until late 1945/46.

Britain employed commercial diesels early in teh war which were on the inefficient side but still better than Japanese and Italian early models. Work on (allegedly purpose-made) tank diesels happened some time around 1940-41 but they were made for no more than 350 hp, so unsuitable for the needs of the new tank programs by then. Harry Ricardo briefly worked on a family of H16/24 and I6/8 diesels from 1939 onwards which were quite efficient and could deliver up to 560 hp unsupercharged and 720 supercharged (not even mentionning TOG's Paxman Ricardo), but Ricardo was too busy on aircraft engines and the Army focused more on the Meteor.

America was very unlucky as the Guiberson radials tried before the war were fundamentally flawed and Buda/Guiberson was not actually interested enough to redesign them accordingly. The Detroit Diesels were good but it was too late to expand production enough to make a real surplus, considering these engines were in very high demand for naval assets. Caterpillar diesel radials and half-radials were too late. George H Rarey, an officer involved in tanks in the interwar period, recommended diesels (albeit with a rather ambitious desire for 5 hp per pound of engine weight), especially in flat and radial forms. Ironically, the target power ouputs (25-30 hp per ton on the US interwar tanks) translated to 375-450 hp for the medium tank and 187.5-225 hp for the light tank, which was right in the class needed for the main US tanks fielded during the war.

French tank inspectors were quite interested in diesels ever since 1929 or so, with some in development for Renault FT and FCM 2C modernizations. The B2, B3 battle tanks and BB fortress tank all employed dedicated tank diesels, half or more of the light tank entries in 1933-35 used diesels (but were not adopted for unrelated reasons), the ARL and AMX 45t fortress tanks used diesels (commercial and dedicated alike), and AMX went with only diesels ever since it started working on new tanks. Dedicated engines (instead of commercial/aircraft engines until then) for 65 octane gasoline remained the norm for the new developments of 1939-40 - as by this point, mass adoption of diesels in a sea of gasoline engines would face an uphill struggle just like in the US.

The USSR was unique in that
- it was used to high output tank engines so the V-2 was suitable for the entire war, while even dedicated engines designed elsewhere could well have been too small and weak to serve the entire war (in tanks at least)
- V-2 development started all the way back to 1932, so that the engine was already well-developped (if a little short-lived still) when Barbarossa happened
- the state of the Soviet gasoline process industry and civilian road economy was such that road gasoline engines were not particularly important, unlike certain Western countries.

Even then, Harry Ricardo noted that before WW2, the British had moved on to diesel engines for heavy trucks, such that there weren't many high power gasoline engines in use.

So other than the Soviets, most belligerents had not made a serious dieselization effort (with dedicated, high output designs) until they were already too deep in WW2 to transition.

I previously posted these US Army memos on their plans diesel engines in tanks.

Napier keeps making liquid-cooled engines in 1930?

The attached collection of US army memos shows that was a lot of effort made to dieselize but eventually gasoline was preferred.

ww2aircraft.net

 

[Reluctant Poster]

I previously posted these US Army memos on their plans for diesel engines in tanks.

Napier keeps making liquid-cooled engines in 1930?

The attached collection of US army memos shows that was a lot of effort made to dieselize but eventually gasoline was preferred.

ww2aircraft.net