AM-34 was designed in Italy, while the AM-42 have had only 'some Soviet input'? You are unbelievable, Greg.
BTW, the standard Soviet fuel was 95 oct, suspiciously close to the German of 96 oct C3 fuel, and not that far away from Allied 100 oct.
Inline engines: Modern air cooled vs WWII water cooled
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AM-34 was designed in Italy, while the AM-42 have had only 'some Soviet input'? You are unbelievable, Greg.
BTW, the standard Soviet fuel was 95 oct, suspiciously close to the German of 96 oct C3 fuel, and not that far away from Allied 100 oct.
wuzak
Captain
There was also these:
Daimler Benz DB 605: 2,176 CID (35.7l)
Junkers Jumo 211: 2,135 CID (35l)
Junkers Jumo 213: 2,135 CID (35l)
Rolls-Royce Griffon: 2,239 CID (36.7l)
Napier Sabre: 2,238 CID (36.7l)
Shortround6
Major General
I would also note that neither the Merlin or the Allison were designed with 100 octane (and especially higher PN) fuel in mind.
Both engines were well into the test stage (at least ground testing) by the time 100 octane fuel was being tested or used in record breaking flight. The fuel used by Howard Hughes to set the speed record in 1935 was said to have cost 10 times per gallon what "normal" aviation fuel cost. People could guess that 100 octane fuel was coming but predicting when would be a huge gamble to base the design/production of an engine on.
Both engines were well into the test stage (at least ground testing) by the time 100 octane fuel was being tested or used in record breaking flight. The fuel used by Howard Hughes to set the speed record in 1935 was said to have cost 10 times per gallon what "normal" aviation fuel cost. People could guess that 100 octane fuel was coming but predicting when would be a huge gamble to base the design/production of an engine on.
You are surely correct Greg, I have no doubt that RR could have got the Vulture to work EVENTUALLY, but it was shelved in favour of more merlin and some Griffon development. That is a big clue. In time of war RR had almost unlimited call on resources people technology and money but still had to shelve the Vulture. Technology moved on and the merlin ended up producing what the Vulture was originally asked to (2000BHP). OK the USA is bigger than the UK but if the UK couldnt find the people to develop the Merlin Griffon and Vulture at the same time there is no chance that an engine like the vulture (or even the Merlin) would be privately developed today, these engines only exist because of the pressing urgency of a war coming and various nations in various ways pouring resources at the problem. Eventually the development was mainly with super and turbo charging and quickly the "middle man" of the piston engine was cut out of the equation.
The lancasters that bombed the Tirpitz from Russia ran like dogs on Russian fuel.
GregP
Major
Hi Tomo,
Not quite sure what you mean, but the AM-42 is directly traceable to the Italian-designed AM-34, with changes made by Soviet engineers. That's all I was saying. Not surprisingly, the Soviets had engineers working for them from many different countries, and it is hard to say what nationality made all the required changers to produce the AM-42 from the AM-34. In the Soviet Union, the design bureau takes credit, but it might have been almost anyone who really made the changes.
Not quite sure what you mean, but the AM-42 is directly traceable to the Italian-designed AM-34, with changes made by Soviet engineers. That's all I was saying. Not surprisingly, the Soviets had engineers working for them from many different countries, and it is hard to say what nationality made all the required changers to produce the AM-42 from the AM-34. In the Soviet Union, the design bureau takes credit, but it might have been almost anyone who really made the changes.
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Indeed, the Wikipedia article claims that M-34 was designed in Italy, referencing it to an 1944 US report that deals with tank engines.
Soviets/Russians say, that lineage is like this: BMW VI -> M-17 ('motor 17', license built; also used on tanks) -> M-34 (a wholesale redesign of the M-17 by Mikulin's team, keeping just bore, stroke and, roughly, external dimensions; later the reduction gear was installed, among other modifications) -> AM-35 and AM-35A ('Alexandar Mikulin'; further improvement of the M-34). The AM-37 and AM-39 were further developments, aimed for use on fighter aircraft, but the need for the AM-38 and -38F (both for Il-2) was more urgent. The AM-42 was used on Il-10, a 2000 HP engine for low altitudes, with 'slow' supercharger just like the AM-38 line, counter-ballanced crankshaft for better RPM, and low CR for greater boost.
The M-34 initially did not featured supercharger nor reduction gear, same as the M-17 - just when the Italians were supposed to engineer these and pass it to the Soviets?
Anyway, here is what the Russians have to say, from here:
In 1930 Mikulin embarked ideas that matured him back in 1928 .: creation engine, more powerful than the M-17. At the initial stage, he met strong opposition from the US* leadership. Despite this, in May 1930 Mikulin managed to get the approval of his proposed layout engine. Mikulin was well aware that the new process equipment plant nobody will. Therefore, for the rapid implementation of the new motor in a series of its main dimensions, the diameter of the cylinder and the piston stroke were kept the same as that of the legacy M-17. This decision determined the choice of the Rybinsk plant number 26 for the organization of all further work.
Development of working drawings was completed in July 1930. In October, began testing the prototype unit, and by August 1931 was carried out and break-in the preliminary test "full" motor. From August 2 to November 7 engine, designated the M-34, has successfully passed the 100-hour state tests and in the beginning of 1932 was transferred into production at the Moscow plant № 24. In parallel, it was produced, and the formation of the Central Institute of Aviation Motors (CIAM) where Mikulin was appointed chief designer. M-34 possessed outstanding for its time, technical data and surpasses the best foreign samples. Its rated power is 750 hp, and takeoff - 850 hp when the dry weight of 535 kg.
* hiccup of the google translator - not the US, but NAMI (cyrilic НАМИ; Ð"ÐЦ Ð*Ф ФÐ"УП "ÐÐМИ"), an institution that oversaw engine development.
Soviets/Russians say, that lineage is like this: BMW VI -> M-17 ('motor 17', license built; also used on tanks) -> M-34 (a wholesale redesign of the M-17 by Mikulin's team, keeping just bore, stroke and, roughly, external dimensions; later the reduction gear was installed, among other modifications) -> AM-35 and AM-35A ('Alexandar Mikulin'; further improvement of the M-34). The AM-37 and AM-39 were further developments, aimed for use on fighter aircraft, but the need for the AM-38 and -38F (both for Il-2) was more urgent. The AM-42 was used on Il-10, a 2000 HP engine for low altitudes, with 'slow' supercharger just like the AM-38 line, counter-ballanced crankshaft for better RPM, and low CR for greater boost.
The M-34 initially did not featured supercharger nor reduction gear, same as the M-17 - just when the Italians were supposed to engineer these and pass it to the Soviets?
Anyway, here is what the Russians have to say, from here:
In 1930 Mikulin embarked ideas that matured him back in 1928 .: creation engine, more powerful than the M-17. At the initial stage, he met strong opposition from the US* leadership. Despite this, in May 1930 Mikulin managed to get the approval of his proposed layout engine. Mikulin was well aware that the new process equipment plant nobody will. Therefore, for the rapid implementation of the new motor in a series of its main dimensions, the diameter of the cylinder and the piston stroke were kept the same as that of the legacy M-17. This decision determined the choice of the Rybinsk plant number 26 for the organization of all further work.
Development of working drawings was completed in July 1930. In October, began testing the prototype unit, and by August 1931 was carried out and break-in the preliminary test "full" motor. From August 2 to November 7 engine, designated the M-34, has successfully passed the 100-hour state tests and in the beginning of 1932 was transferred into production at the Moscow plant № 24. In parallel, it was produced, and the formation of the Central Institute of Aviation Motors (CIAM) where Mikulin was appointed chief designer. M-34 possessed outstanding for its time, technical data and surpasses the best foreign samples. Its rated power is 750 hp, and takeoff - 850 hp when the dry weight of 535 kg.
* hiccup of the google translator - not the US, but NAMI (cyrilic НАМИ; Ð"ÐЦ Ð*Ф ФÐ"УП "ÐÐМИ"), an institution that oversaw engine development.
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The Continetal AV-1790 engine needs to be mentioned. An air cooled V-12 5.75 inch (146mm) bore x 5.75 inch (146mm) stroke, it started in the 1950s as a 600 hp gasoline (spark ignition) engine. Later versions were compression ignition (diesel), with the latest offering 1200 HP @ 2400 rpm. It continues to be availble as an engine for tanks and other heavy military vehicles.
I am sure that if the governor were recalibrated to allow operation at 3000 or even 3200 rpm, that it could produce 1500 HP or more, for 5 minutes. That is starting to get into Merlin / DB 601 / AM-37 kind of power.
Downside is, at least according to the internet, it is a real porker, weighing 4000 pounds or more AS A TANK ENGINE. Before we immediately discount this engine, we need to consider the differences between a tank engine and an aircraft engine. Since a tank has to be able to pull full power while moving oh so slowly across the desert, the 4000 pound weight includes high capacity fans for cooling which an aircraft engine lacks. The quoted weight includes an oil cooler, also sized for desert operation, while the oil cooler is usually not included in the quoted weight of an aircraft engine. There is also likely a lot of extra metal in a tank engine (compared to an aero engine) to allow it to run after the concussion of a shell hit against the armour. Plus what sort of expectation for time between overhauls on a tank engine compared to a aircraft engine.
That is all I think I know.
I am sure that if the governor were recalibrated to allow operation at 3000 or even 3200 rpm, that it could produce 1500 HP or more, for 5 minutes. That is starting to get into Merlin / DB 601 / AM-37 kind of power.
Downside is, at least according to the internet, it is a real porker, weighing 4000 pounds or more AS A TANK ENGINE. Before we immediately discount this engine, we need to consider the differences between a tank engine and an aircraft engine. Since a tank has to be able to pull full power while moving oh so slowly across the desert, the 4000 pound weight includes high capacity fans for cooling which an aircraft engine lacks. The quoted weight includes an oil cooler, also sized for desert operation, while the oil cooler is usually not included in the quoted weight of an aircraft engine. There is also likely a lot of extra metal in a tank engine (compared to an aero engine) to allow it to run after the concussion of a shell hit against the armour. Plus what sort of expectation for time between overhauls on a tank engine compared to a aircraft engine.
That is all I think I know.
Shortround6
Major General
It took a while ( like a couple of decades) but the late 80s Continetal AV-1790 engines were being offered with 1000 hour "red seal" warranty and a Mean Time Between Overhauls of 2550 hours.
These are NOT small engines length is about 70 in but there is no reduction gear (think P-39 engine), height is just under 44 in but the width is about 55in NOT including the carbs on the gas versions or the turbos on diesels.
Early/ mid 90s versions were being offered at 1200hp with 1000 hour "red seal" warranty.
These are NOT small engines length is about 70 in but there is no reduction gear (think P-39 engine), height is just under 44 in but the width is about 55in NOT including the carbs on the gas versions or the turbos on diesels.
Early/ mid 90s versions were being offered at 1200hp with 1000 hour "red seal" warranty.
It seems to me that radials were never really fully developed.
Two of the most remarkable fighters of WW2 was the Fw 190A and the Vought Corsair.
The Corsair was the first American aircraft to exceed 400mph and I believe that was a result of the USN spec PW R2800 which had a two stage multispeed (independent drive) supercharger with intercooler that could maintain power into the thin air of high altitude where parasitic or form drag was less.
Also remarkable is the Fw 190A which managed this feat with only a single stage two speed supercharger likely as a result of the low drag installation made possible by the forced fan cooling which reduced engine cooling inlet area and eliminated the area subtended by the oil cooler in the propeller blade area.
Had the two techniques been combined I believe we would have radial engines beating water cooled engines.
Such an engine might have been the BMW 801R which had a two stage 4 speed (independent drive) intercooled engine, it was as long as the German inline engines due to the placement of the intercooler.
The 801R was essentially the 2000hp BMW 801TS or E used in the Fw 190A9 but with the greatly modified supercharger. Although the 801R couldn't fit into the Fw 190A it could fit into the much larger Ta 152.
The Ta 152 with 2000hp BMW 801R was expected to be about 24mph faster (about 448 mph) than the much smaller Fw 190A9 with the equally powerful 2000hp BMW 801TS.
These engines were expected to receive water methanol injection, the Fw 190A9 having added the provision for the tank, for about 10% more power and ultimately grow to 2600hp with stronger components.
The only 400+ mph aircraft in service till 1944 with single stage superchargers I believe was the Typhoon and Fw 190, which had almost exactly the same speed.
The BMW 801R was suspended in mid 1944 after a damaging raid on the BMW plant removed hope of producing it in time.
It seems to me the big US engine could have benefitted from forced induction cooling, especially during the take-off phase for bombers when there is minimal airflow and for high speed flight. Forced fan cooling was used in the pusher propeller versions of the R-4360 and maybe some other versions.
Two of the most remarkable fighters of WW2 was the Fw 190A and the Vought Corsair.
The Corsair was the first American aircraft to exceed 400mph and I believe that was a result of the USN spec PW R2800 which had a two stage multispeed (independent drive) supercharger with intercooler that could maintain power into the thin air of high altitude where parasitic or form drag was less.
Also remarkable is the Fw 190A which managed this feat with only a single stage two speed supercharger likely as a result of the low drag installation made possible by the forced fan cooling which reduced engine cooling inlet area and eliminated the area subtended by the oil cooler in the propeller blade area.
Had the two techniques been combined I believe we would have radial engines beating water cooled engines.
Such an engine might have been the BMW 801R which had a two stage 4 speed (independent drive) intercooled engine, it was as long as the German inline engines due to the placement of the intercooler.
The 801R was essentially the 2000hp BMW 801TS or E used in the Fw 190A9 but with the greatly modified supercharger. Although the 801R couldn't fit into the Fw 190A it could fit into the much larger Ta 152.
The Ta 152 with 2000hp BMW 801R was expected to be about 24mph faster (about 448 mph) than the much smaller Fw 190A9 with the equally powerful 2000hp BMW 801TS.
These engines were expected to receive water methanol injection, the Fw 190A9 having added the provision for the tank, for about 10% more power and ultimately grow to 2600hp with stronger components.
The only 400+ mph aircraft in service till 1944 with single stage superchargers I believe was the Typhoon and Fw 190, which had almost exactly the same speed.
The BMW 801R was suspended in mid 1944 after a damaging raid on the BMW plant removed hope of producing it in time.
It seems to me the big US engine could have benefitted from forced induction cooling, especially during the take-off phase for bombers when there is minimal airflow and for high speed flight. Forced fan cooling was used in the pusher propeller versions of the R-4360 and maybe some other versions.
The Fw-190 was fast as the Corsair because it was a small aircraft, compared with the Corsair. It's wing was even smaller than of Spitfire, P-40 or Zero's, or the P-51, being of reasonably modern profile and thickness. The modest size was the key to a good/excellent performance of the Bf-109, Yak La fighters, MC.202/205.
We don't know how much the convoluted air streaming through the oil cooler of the BMW-801 added to the drag. The engine installation was of low drag, but significantly helped by the 801 having a diameter of only 50.5 in.
The R-2800 was certainly fully developed - two stage (available in early 1942) or turbo compressor, with inter-cooler, capability for water injection, even a cooling fan was successfully tested.
The XP-47J, 500+ mph was claimed (though it's a turbo): link. The P&W and NACA were experimenting with fan cooled radial before Pearl Harbor was attacked.
Plus the Bf-109F-4, Gustavs prior the G-6 (even without Notleistung ), the P-51A.
Shortround6
Major General
The US and British pushed them about as far as they could go. After 1945 the operators wanted durability and reliability more than peak HP. Yes, they wanted to get out of hot and high airports or ones with short runways ( I Believe Rome had a bad reputation in the 50s) but operating hundreds of hours between overhauls was a higher priority.
The R-2800 hit 2800 HP in service in late 1944 and 1hp per cubic in was doing pretty good for an air-cooled engine for a lot of years. In the 1950s the R-2800 commercial engines were rated at 2400hp wet (water or water/methanol) for take-off on 100/130 fuel and 2050hp dry. On 108/135 they could make 2500hp at 2500ft wet and 2200hp at 4500ft dry. Two speed single stage superchargers.
Bristol got the Centaurus up to 3220hp at 3,000ft military rating wet, which isn't too shabby for a 3270cu in engine with single stage single speed supercharger. Granted altitude performance wasn't that good.
Bristol had also pushed the Hercules to 2090hp at 3000ft dry on 100/130 fuel.
All of these were without fan cooling as was the Wright R-3350 pulling 2800hp at 4500ft take of rating (higher airports) using 115/145 fuel. The Turbo compound managed 3500hp wet for take-off.
Wright managed to pull 1525hp from the 9 cylinder R-1820 with 115/145 fuel but these engines had few, if any, parts in common with the wartime 1200hp R-1820s.
But the air-cooled engines were only beating the liquid cooled engines due to size. The Big Wright and the Centaurus being around 54 liters and using 18 cylinders. The RR Griffon used in Shackleton PBs was good for 2455hp take-off wet at 25bs boost and 100/130 fuel from 36.7 liters.
The R-2800 hit 2800 HP in service in late 1944 and 1hp per cubic in was doing pretty good for an air-cooled engine for a lot of years. In the 1950s the R-2800 commercial engines were rated at 2400hp wet (water or water/methanol) for take-off on 100/130 fuel and 2050hp dry. On 108/135 they could make 2500hp at 2500ft wet and 2200hp at 4500ft dry. Two speed single stage superchargers.
Bristol got the Centaurus up to 3220hp at 3,000ft military rating wet, which isn't too shabby for a 3270cu in engine with single stage single speed supercharger. Granted altitude performance wasn't that good.
Bristol had also pushed the Hercules to 2090hp at 3000ft dry on 100/130 fuel.
All of these were without fan cooling as was the Wright R-3350 pulling 2800hp at 4500ft take of rating (higher airports) using 115/145 fuel. The Turbo compound managed 3500hp wet for take-off.
Wright managed to pull 1525hp from the 9 cylinder R-1820 with 115/145 fuel but these engines had few, if any, parts in common with the wartime 1200hp R-1820s.
But the air-cooled engines were only beating the liquid cooled engines due to size. The Big Wright and the Centaurus being around 54 liters and using 18 cylinders. The RR Griffon used in Shackleton PBs was good for 2455hp take-off wet at 25bs boost and 100/130 fuel from 36.7 liters.
swampyankee
Chief Master Sergeant
- 3,954
- Jun 25, 2013
When I worked at Lycoming (on the ALF-502), the word around the office was that the M-60 tank engine had a TBOH of less than 50 hours. The AGT-1500, once somebody competent designed the air filter, was well over 1,000. The AVDS-1790 was a very complicated, very high-performance diesel. As one little item, it had a variable compression ration, achieved by hydraulically varying the length of the connecting rods.
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- Thread starter
- #54
Never heard of that - neat idea.
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Shortround6
Major General
It was big back in the 50s when NATO was gung-ho on Multi-fuel engines. Fill the fuel tanks with what ever you could find, flip a few switches or twist a dial on the control panel and away you go 
Turns out it didn't work all that well, Some engines lost 10-20% in power running on gasoline compared to diesel fuel and the increased cost of the engines, the break downs, and maintenance/overhaul pretty well killed it.
It was reason the US started down the Turbine engine path though, Early ground use turbines were touted as being able to run on anything from home heating oil to peanut oil. Eco-Friendly tanks?
Turns out it didn't work all that well, Some engines lost 10-20% in power running on gasoline compared to diesel fuel and the increased cost of the engines, the break downs, and maintenance/overhaul pretty well killed it.
It was reason the US started down the Turbine engine path though, Early ground use turbines were touted as being able to run on anything from home heating oil to peanut oil. Eco-Friendly tanks?
- Thread starter
- #56
Shortround6
Major General
Might be very indirect. Like if there are policies on taxes on diesel fuel vs gasoline or something.
In the US the botched attempt by GM to make Diesel cars certainly hurt their reputation and now with many states raising the taxes on diesel fuel so it costs a lot more than high test gas at the pump ( to get money from the truckers) the economics of a diesel car need close looking at.
I live in Western Connecticut, perhaps not more than 100 miles from you. Our fuel taxes mean gas costs 30-40 cents more per gallon than NJ and we have to pump our own, the gas station isn't paying gas attendants. We such 'spotty/patchy' fuel pricing coming up with long term product development might be hard for the car companies.
In the US the botched attempt by GM to make Diesel cars certainly hurt their reputation and now with many states raising the taxes on diesel fuel so it costs a lot more than high test gas at the pump ( to get money from the truckers) the economics of a diesel car need close looking at.
I live in Western Connecticut, perhaps not more than 100 miles from you. Our fuel taxes mean gas costs 30-40 cents more per gallon than NJ and we have to pump our own, the gas station isn't paying gas attendants. We such 'spotty/patchy' fuel pricing coming up with long term product development might be hard for the car companies.
The taxes are about the same for the gas and diesel in perhaps whole Europe, not just in the EU; the diesel is in most countries here a bit cheaper. Taxes can amount to 70% of the gas price (ie. 3 kn for the gas itself, 7 kn to the govmnt).
What makes the diesels attractive is the low consumption of diesel engines vs. gasoline engines - one will spend 60 euros worth of diesel for a trip where it will cost 100 euros of gasoline. On about the same speed, and same type of car.
Shortround6
Major General
That is what complicates things over here. If our diesel costs 10-15% more than the gasoline AND the diesel car cost more money to begin with than the same car with a gas engine the payback is a LOT slower.
Diesel pick up trucks are popular but gas pickup trucks get horrendous gas mileage and have big fuel tanks. The payback is much quicker. If you are looking at a car that gets 35mpg (real and not advertised) and diesel that gets 45mpg (28% better) and the diesel fuel costs that 10-15% more? and the car costs ???? more (VW Jetta, cheapest with gas engine is $4,000 cheaper than cheapest Jetta Diesel).
If the diesel fuel was as cheap as the gas or cheaper it would be no-brainer. As it is you need an accounting program to figure out if you are better off from state to state.
Diesel pick up trucks are popular but gas pickup trucks get horrendous gas mileage and have big fuel tanks. The payback is much quicker. If you are looking at a car that gets 35mpg (real and not advertised) and diesel that gets 45mpg (28% better) and the diesel fuel costs that 10-15% more? and the car costs ???? more (VW Jetta, cheapest with gas engine is $4,000 cheaper than cheapest Jetta Diesel).
If the diesel fuel was as cheap as the gas or cheaper it would be no-brainer. As it is you need an accounting program to figure out if you are better off from state to state.
swampyankee
Chief Master Sergeant
- 3,954
- Jun 25, 2013
It was big back in the 50s when NATO was gung-ho on Multi-fuel engines. Fill the fuel tanks with what ever you could find, flip a few switches or twist a dial on the control panel and away you go
Turns out it didn't work all that well, Some engines lost 10-20% in power running on gasoline compared to diesel fuel and the increased cost of the engines, the break downs, and maintenance/overhaul pretty well killed it.
It was reason the US started down the Turbine engine path though, Early ground use turbines were touted as being able to run on anything from home heating oil to peanut oil. Eco-Friendly tanks?
The AGT-1500 could run on just about anything. I know it was tested on JP-5, JP-4, Jet-A, Jet-A1, road diesel, whatever flavor of diesel the US Army used, and various flavors of gasoline. Leaded gas left a lot of deposits behind. Gas turbines can run on all sorts of crap: when I worked at Lycoming, there was an industrial T-53 that was running on pulverized peat.
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