Why no Luftwaffe-derived engines in Heer vehicles?

[Milosh]

Despite the commonplace assumption, the new-generation Packard marine engine, initially tagged the 4M-2500, was anything but a repopped Liberty. Instead, Vincent started with a clean sheet and designed a four-stroke, 60-degree V-12 with an aluminum block with a bore of 6.04 inches and a 6.50-inch stroke, which brought it to 2,490 cubic inches. Weighing 2,900 pounds, the 4M-2500 had four valves per cylinder, a 6.4:1 compression ratio, and a centrifugal supercharger with intercooler. A Holley 1685F aircraft carburetor supplied the fuel, 100-octane gasoline, fired by two spark plugs per cylinder. The first engines developed 1,200hp, but improved versions with higher boost levels nominally made 1,500hp. Packard built 14,000 marine engines during the war, three of which went into each of the Navy's 768 PT boats, two astern and one amidships for better service access.
https://www.hemmings.com/stories/article/powering-to-victory

 

[Shortround6]

I am not sure if the Marine engine was a clean sheet of paper from the A-2500 aircraft engines of the 1920s but those were certainly a major change from the Liberty.

Liberty had a 45 degree angle between the banks and 2 valves per cylinder. A Liberty weighed 858lbs without reduction gear and had a 5in bore and a 7in stoke.

The aircraft engines, unsupercharged, went about 1120lbs without reduction gear. They were rated at 800-810 hp. They had, as Milosh has stated, 4 valve heads, a 60 degree angle between the cylinder banks and the 6.5in stroke. Bore may be in dispute, most sources say 6.375in for a displacement of 1540cu in. Marine engines got thicker cylinder walls?
Later versions of the aircraft engines did get superchargers.

Packard at the same time (early to mid 20s) was also building an A-1500 with pretty much the same features as the A-2500 except smaller. There were also a number of experimental engines including a batch of eleven A-2025s built in 1920 (or started then) with the 60 degree V and 4 valves per cylinder and the 6.5 in stroke.

for a complete list of Packard aircraft engines see; http://www.enginehistory.org/Piston/Packard/StatsAllPackardAero.pdf

 

[swampyankee]

Not sure what they would put it in unless some of the experimental heavy tanks T-28 and T-29 series? The T-29 got the Ford V-12.

One could argue that the Ford 60 degree V-8 GAA was an aero-derivative engine as it was derived from a V-12 that Ford was proposing to build instead of license building Merlins. The Ford aero V-12 never got picked up, but when a tank engine was needed, they adopted the V-12 to V-8 form and, voila, tank engine! Later, there was a V-12 version developed when the V-8 was too small.

Some post-war tanks used aero-derivative engines, such as the Swedish S-tank, which used a CODAG power plant. AAI was working on a light tank powered by a LTS-101 which ended up going nowhere. While aero engines are highly developed, the dedicated tank diesels that have been produced by MTU, SACM, and Continental in the west and the Soviet/Russian equivalents are all highly specialized and quite expensive. They're also not exactly long-lived. When I worked at Lycoming, the most powerful variant of the AVDS-1790 in use at the time (late 1970s to early 1980s) had a mean time between removal of less than 50 hours and an MTBOH of less than 250. The AGT-1500 had a MTBR, once Chrysler found out how to make an air filter, of over 500, and, when I left Lycoming for greener pastures, had an expected MTBR (based on service testing) greater than an individual tank's expected peacetime operating life. Tank diesels are not like the diesels in long-haul trucks; they're more like the diesel equivalent of the engines used for LeMans racers.

 

[Shortround6]

When the advertising brochures of 1960/70s tanks start touting how fast a complete engine or powerpack change can be done in field (assuming a handy 5 ton crane and a spare engine/powerpack) one could assume that engine life was not very long even without seeing the numbers.

 

[Shortround6]

Getting back to the original question

Why didn't German army vehicles use aeroplane-derived engines?

The Germans didn't really need anything that large until they got to the Tiger tank.
Maybach, for whatever reason, (political?) had the lock on engines for tracked vehicles made in Germany. Unfortunately for the Germans the weights of the tanks tended to rise without any increase in engine size, Tiger excepted, which went from a 21 liter engine to a 23 liter engine.
Czech vehicles and armoured cars didn't use Maybachs.

for most other vehicles (anything except medium/heavy tanks) in other armies Aircraft engines weren't needed. The Americans replaced the small radials in the M2-M3 light tanks with a pair of 5.7 liter Cadillac car engines in the M3A3, M-5, M-24 and a number of self propelled guns. The Australians used three of these engines ganged together in the Sentinel tank.

It may have been heavy and unsophisticated but it worked. It freed up Continental to make engines for aircraft.

What counted on tanks was the size of the whole engine package.
While on aircraft engine weight was important, on tanks it was not, another 300-400lbs of engine weight in a 20-30 ton tank? under 1%.
Armor is 40lbs per sq ft per inch of thickness. adding 6 in of length to an engine compartment could add several hundred pounds of armor counting both sides, top and bottom.

You also need to match the engine to the transmission, Sticking an 800hp engine on a transmission designed for 500hp means a lot of broken parts. Getting a tank up to speed means a lot of full throttle time between each shift.

 

[Koopernic]

I find it interesting that the Italians used diesels in their tanks instead of designing something off of their aircraft engines. With a limited industrial base, Italy seems a good candidate for consolidation of designs across services.

. It would seem the British, Italians and Japanese all had the expedient of adapting a bus or truck engine for their tanks. The British moved on to the Merlin derived Meteor since they started to build tanks that were exceptionally heavy (like Churchill) or meant to be exceptionally fast. British tanks have a tradition of emphasising exceptional ground and object crossing capability, good track protection, good armour. I think this can be seen in Matilda, Churchill, Chieftain and Challenger so they tended to focus a little less on power. To an extent they sacrifice top speed but they often had very good acceleration within their speed range. Furthermore does top speed matter when your tank can't cross certain kinds of difficult terrain or its tracks are damaged?

 

[Admiral Beez]

. It would seem the British, Italians and Japanese all had the expedient of adapting a bus or truck engine for their tanks. The British moved on to the Merlin derived Meteor since they started to build tanks that were exceptionally heavy (like Churchill) or meant to be exceptionally fast. British tanks have a tradition of emphasising exceptional ground and object crossing capability, good track protection, good armour. I think this can be seen in Matilda, Churchill, Chieftain and Challenger so they tended to focus a little less on power. To an extent they sacrifice top speed but they often had very good acceleration within their speed range. Furthermore does top speed matter when your tank can't cross certain kinds of difficult terrain or its tracks are damaged?

Best engine in a "British" tank was probably the GM diesel in the Canadian-made Valentine.

 

[Koopernic]

Well they did TRY to....Panzer VIII Maus.

However broadly I cant imagine a worse tank engine than an aero engine.

1) Aero engines are hideously expensive because they have to be very high output AND very low weight and very small size. At least 1 and probably 2 of those
dont matter for a tank.

SNIP.

Getting back to the original question

The Germans didn't really need anything that large until they got to the Tiger tank.
Maybach, for whatever reason, (political?) had the lock on engines for tracked vehicles made in Germany. Unfortunately for the Germans the weights of the tanks tended to rise without
It may have been heavy and unsophisticated but it worked. It freed up Continental to make engines for aircraft.
SNIP
You also need to match the engine to the transmission, Sticking an 800hp engine on a transmission designed for 500hp means a lot of broken parts. Getting a tank up to speed means a lot of full throttle time between each shift.

Guiberson R-1020 and Packard R-980 were both aircraft engines was a US aircraft diesel adapted to use in tanks, and used in quantity.

There are probably vast numbers of reasons why Germany didn't use aero-derivative engines in their tanks, starting with lavish pre-war spending on tank development and continuing with a supply system that didn't try to consolidate multiple streams of government procurement until fairly late in the war.
SNIP

Looking at its history I think the argument can be made that Maybach as a company had some unique markets and capabilities that made it well placed to produce a specialised tank engine.

Wilhelm Maybach was a partner of Gotlied Daimler, in 1911 he argued with the Directors and left to form his own company which traded under several names until being known as Maybach. The company still exists as MTU. He produced aircraft engines and zeppelin engines. In 1919 he put his son Karl as Director and the company had to start making automobile engines since manufacture of aircraft engines was forbidden by the Treaty of Versailles. This forced the company to start making cars since most car makers already made their own engines. They also started making marine diesels, zeppelin diesels, locomotive engines and stationary engines. Maybach automobiles were ultra luxury cars for bankers and industrialists that spared no expense. By the mid 1930s they were making V12 saloon cars with 150kW 8 litre V12 engine cars with 7 speed pneumatically operated gearboxes capable of 190km/h.

You can see those 8L V12 turning up in half tracks. Being able to make big engines and being able to design and make high performance bespoke engines meant increasing their size to 12L (HL120) or 23L (HL230) was relatively easy. They were not truck or bus engines but high performance engines. The HL in HL120 or HL230 stands for Hoch Leistung or "High Performance" so they didn't tend to be like bus or truck engines but more compact and powerful.

Maybach's ability to produce transmissions capable of pneumatic operation also put them in a good position for the complex tank steering mechanism.

Certainly German rearmament spending was a factor but they were also coming from way way behind with absolutely no tanks Panzer I and Panzer II really being derived from commercial vehicles. One would think that when issuing a specification for a new tank, like the German Heer did with Panzer III and Panzer IV they would make sure that there was an appropriate engine.

These engines were reliable. The al alloy block HL210 initially used in Tiger and Panther, prior to being replaced with the slightly enlarged cast iron block HL230 was also good. The Panther had an installation problem in that the engine had been placed in a walled of aquarium structure so that the Panther had to be able to ford rivers since it was to heavy to cross many bridges. This enclosed space gave it a installation and overheating problem.

The HL230 at 585 hp was OK on a 43 ton Panther or 56 ton Tiger I. The 55 ton Chieftain tanks entered service with 585 hp as well in the 1960s. The plans for this engine included fuel injection to achieved 800-900hp and supercharging to achieve 1200hp.

 

[Shortround6]

It would seem the British, Italians and Japanese all had the expedient of adapting a bus or truck engine for their tanks

When the tanks weighed 7-14 tons the use of bus/truck engines was a useful expedient.

Furthermore does top speed matter when your tank can't cross certain kinds of difficult terrain or its tracks are damaged

It is not just the tracks. The crew was often injured by slamming into objects inside the tank in "high" speed cross country travel. High is in quotes because this could be as little as 8-10mph depending on type of suspension and actual terrain.
This was part of the promise of the Christie suspension, long wheel travel to soak up the bumps without bouncing the tank and crew around too bad. Now that you could actually go faster on worse surfaces than a paved road you did need larger engines.
In general, for moderate mobility you needed about 10hp per ton and this could be achieved without going to aircraft engines until the tank weights were in the high 20 to 30 ton range. This ignores transmissions and multiple gear sets (as in more than 4) could, to some extent, make up for a marginal engine. It does help if the driver can actually change gears on the transmission without the aid of a good mallet/hammer
Good transmissions and steering gear are often overlooked in discussing tank mobility.
British went for the Meteor because instead of settling for 15-18hp per ton they wanted 20hp per ton. This was too much for even the Christie suspension of the time as it turned out but it did mean the British didn't have to worry too much about a new tank engine until the 1950s.

 

[Koopernic]

Ignore

 

[Shortround6]

While diesel engines can help tanks achieve much better range than gasoline engines some of the other advantages are not quite as clear cut. Diesel tanks will still burn, and in fact more tanks are destroyed by ammunition fires than by fuel fires.

Most armies used very few diesel powered trucks or other vehicles in the early part of the war meaning that having diesel tanks often complicated the fuel supply situation.

In the 1950s NATO pushed for a "multi fuel" situation in which not only tanks and SP guns ran on diesel but so did light armor and most trucks, at least the ones in the tactical catagory. But gasoline was supposed to able to be used if needed,
Ideally the driver was supposed to be able to adjust the engine for best performance by turning a dial or knob on his control panel to suit the the type of fuel. This lead to a bunch of very expensive prototype engines and some limited production ones but eventually the whole thing was forgotten nad most vehicles just used Diesel fuel.

The Germans in the advance across France are reputed to have refueled at French petrol stations on occasion. In NA the capture of enemy fuel and supply depots often meant the continuation of an advance or not. Or at least eased the supply situation for a few days. Using Diesels when your opponents use gasoline tends to diminish the value of captured supply dumps.

 

[Koopernic]

While diesel engines can help tanks achieve much better range than gasoline engines some of the other advantages are not quite as clear cut. Diesel tanks will still burn, and in fact more tanks are destroyed by ammunition fires than by fuel fires.

Most armies used very few diesel powered trucks or other vehicles in the early part of the war meaning that having diesel tanks often complicated the fuel supply situation.

In the 1950s NATO pushed for a "multi fuel" situation in which not only tanks and SP guns ran on diesel but so did light armor and most trucks, at least the ones in the tactical catagory. But gasoline was supposed to able to be used if needed,
Ideally the driver was supposed to be able to adjust the engine for best performance by turning a dial or knob on his control panel to suit the the type of fuel. This lead to a bunch of very expensive prototype engines and some limited production ones but eventually the whole thing was forgotten nad most vehicles just used Diesel fuel.

The Germans in the advance across France are reputed to have refueled at French petrol stations on occasion. In NA the capture of enemy fuel and supply depots often meant the continuation of an advance or not. Or at least eased the supply situation for a few days. Using Diesels when your opponents use gasoline tends to diminish the value of captured supply dumps.

I believe the British with the Chieftains Horizontally Opposed Leyland L60 engine was the only one of the NATO MBT that complied with the multifuel requirement until decades latter when the AGT1500 gas turbine was introduced on the M1 Abrams. The early L60 reliability problems are by some blamed on this requirement. Its hard to see how it caused leaking cylinder liners though it probably caused the initial P/W ratio issue of the 585hp L60. The engine latter achieved a respectable 860hp.

 

[Reluctant Poster]

Using gasoline as the fuel for tanks was a deliberate choice of the western allies. To quote noted tank authority Richard Ogorkiewicz from one of his many books and articles, in particular:

Tanks: 100 Years of Evolution

"By comparison, other armies dissipated their resources by successively developing different types of engines. One reason for the was changes in policy concerning the availability of fuels. In particular, the US National Petroleum Board decode during the Second World War that military vehicles should use spark ignition petrol engines because petrol was considered to be more readily available than diesel fuel. Similar views were held after the war within NATO. As result, engines developed for tanks towards the end of the war and in its aftermath were all petrol engines, and production of petrol-engined tanks such as the US M48 and the British Centurion, did not cease until 1959."

The comparison referred to is with the Soviets Unions standardization on a single diesel engine to power all its medium and heavy armored vehicles. Interestingly, the Japanese were the first to go all diesel for their tanks beginning in 1932.

Ogorkiewicz also states:

"All this was overshadowed by the development of a diesel engine for tanks in the Soviet Union. It began in 1931 and was originally intended to power aircraft as well as tanks, as the M17 petrol engine had done. The idea of using it in aircraft was gradually abandoned, but it retained to its advantage the characteristics of an aero engine and in particular its light weight."

Aero engines and tank engines have a very strong connection.

 

[rinkol]

Having Maybach and Praga focus primarily on AFVs helped to keep the much-needed aircraft engines going to aircraft.

By the way, Daimler's MB500 series marine diesels were based on the DB600 engine.

The Porsche Maus was intended to use DB engines.

 

[rinkol]

I believe the British with the Chieftains Horizontally Opposed Leyland L60 engine was the only one of the NATO MBT that complied with the multifuel requirement until decades latter when the AGT1500 gas turbine was introduced on the M1 Abrams. The early L60 reliability problems are by some blamed on this requirement. Its hard to see how it caused leaking cylinder liners though it probably caused the initial P/W ratio issue of the 585hp L60. The engine latter achieved a respectable 860hp.

 

[swampyankee]

Multi-fuel engines, at least diesel-type multi-fuel engines, need very high compression ratios. The AGT-1500 was able to burn diesel of various qualities, home heating fuel, gasoline (the worst problem was lead oxide deposits), and quite a few other liquid fuels. There was an attempt to get the engine qualified on marine diesel. I don't know how that worked.

Gas turbines can burn all sorts of crap; when I worked for Lycoming there was an LTC-4 (civil version of the T-55) running on pulverized peat.

 

[Koopernic]

Well they did TRY to....Panzer VIII Maus.

However broadly I cant imagine a worse tank engine than an aero engine.

1) Aero engines are hideously expensive because they have to be very high output AND very low weight and very small size. At least 1 and probably 2 of those
dont matter for a tank.

SNIP.

Getting back to the original question

The Germans didn't really need anything that large until they got to the Tiger tank.
.

Using gasoline as the fuel for tanks was a deliberate choice of the western allies. To quote noted tank authority Richard Ogorkiewicz from one of his many books and articles, in particular:

Tanks: 100 Years of Evolution

"By comparison, other armies dissipated their resources by successively developing different types of engines. One reason for the was changes in policy concerning the availability of fuels. In particular, the US National Petroleum Board decode during the Second World War that military vehicles should use spark ignition petrol engines because petrol was considered to be more readily available than diesel fuel. Similar views were held after the war within NATO. As result, engines developed for tanks towards the end of the war and in its aftermath were all petrol engines, and production of petrol-engined tanks such as the US M48 and the British Centurion, did not cease until 1959."

The comparison referred to is with the Soviets Unions standardization on a single diesel engine to power all its medium and heavy armored vehicles. Interestingly, the Japanese were the first to go all diesel for their tanks beginning in 1932.

Ogorkiewicz also states:

"All this was overshadowed by the development of a diesel engine for tanks in the Soviet Union. It began in 1931 and was originally intended to power aircraft as well as tanks, as the M17 petrol engine had done. The idea of using it in aircraft was gradually abandoned, but it retained to its advantage the characteristics of an aero engine and in particular its light weight."

Aero engines and tank engines have a very strong connection.

Agreed, It's easy to forget that the decisions over engine type are sometimes driven at a higher level over logistics issues rather than technical.

The US had the best petroleum refining technology in the world and was well capable of supplying this. There are probably many reasons for this including pull factors such as the mass production of automobiles for increasingly well of American consumers, the type of crude oil that came out of US Oil wells. One of the most interesting ones is post WW1 prohibition that came out of giving women the vote (prominet suffragets were tea totters) and anti German sentiment (Most prominent US brewers were of German heritage). The whisky distillers (Not Moon shiners) found employment in the oil industry and their skills and knowledge increased output of gasoline fractions by 20%. (Petroleum refining in non technical language)

The Japanese learned how to make synthetic diesel from coal by the Fischer Tropsch route from the Germans but their Synthetic gasoline plants by the Bergius Hydrogenation route were a failure due to them bypassing the pilot plant stage, they relied on coal pyrolysis which at most gives 5% liquids and school children collecting pine tree cones (pineol has a RON of over 100), so the Japanese Army had diesel.

i immagine the nature of the crude comming out of Soviet controlled wells were particularly suitable for diesel. Soviet oil refining and fuels technology was nowhere as good as British or American.

Note: British oil refining was also excellent due to them fostering well finance and organised global oil corporations capable of securing oil for the Admiralty and so they made many technical advances such as acid alkylation).

 

[gjs238]

Agreed, It's easy to forget that the decisions over engine type are sometimes driven at a higher level over logistics issues rather than technical.

The US had the best petroleum refining technology in the world and was well capable of supplying this. There are probably many reasons for this including pull factors such as the mass production of automobiles for increasingly well of American consumers, the type of crude oil that came out of US Oil wells. One of the most interesting ones is post WW1 prohibition that came out of giving women the vote (prominet suffragets were tea totters) and anti German sentiment (Most prominent US brewers were of German heritage). The whisky distillers (Not Moon shiners) found employment in the oil industry and their skills and knowledge increased output of gasoline fractions by 20%. (Petroleum refining in non technical language)

The Japanese learned how to make synthetic diesel from coal by the Fischer Tropsch route from the Germans but their Synthetic gasoline plants by the Bergius Hydrogenation route were a failure due to them bypassing the pilot plant stage, they relied on coal pyrolysis which at most gives 5% liquids and school children collecting pine tree cones (pineol has a RON of over 100), so the Japanese Army had diesel.

i immagine the nature of the crude comming out of Soviet controlled wells were particularly suitable for diesel. Soviet oil refining and fuels technology was nowhere as good as British or American.

Note: British oil refining was also excellent due to them fostering well finance and organised global oil corporations capable of securing oil for the Admiralty and so they made many technical advances such as acid alkylation).

Didn't Prohibition come before women's suffrage?

From Wikipedia:
The Eighteenth Amendment (Amendment XVIII) of the United States Constitution established the prohibition of alcohol in the United States. The amendment was proposed by Congress on December 18, 1917, and was ratified by the requisite number of states on January 16, 1919.

The Nineteenth Amendment (Amendment XIX) to the United States Constitution prohibits the states and the federal government from denying the right to vote to citizens of the United States on the basis of sex. Initially introduced to Congress in 1878, several attempts to pass a women's suffrage amendment failed until passing the House of Representatives on May 21, 1919, followed by the Senate on June 4, 1919. It was then submitted to the states for ratification. On August 18, 1920, Tennessee was the last of the necessary 36 states to secure ratification. The Nineteenth Amendment was officially adopted on August 26, 1920.

 

[xylstra]

Are you referring to post war? After the war, all German armament industry was demolished. There was no ability to produce these engines. The post war Heer was not established until 1955. 10 years after the war. It would have been too expensive to restart and retool up the assembly lines. Plus the equipment and plans probably no longer existed, at least not in Germany.

Interesting side-bar remark: In the immediate post-war period the British re-initiated manufacture of the German Tiger tank in limited numbers for evaluation trials in Germany.

 

[DerAdlerIstGelandet]

Interesting side-bar remark: In the immediate post-war period the British re-initiated manufacture of the German Tiger tank in limited numbers for evaluation trials in Germany.

Panthers actually, not Tigers. The German factory finished 9 Panthers under direct British supervision. They were then shipped back to England for testing.