# Inline engines: Modern air cooled vs WWII water cooled



## gjs238 (Oct 29, 2014)

Can modern air cooled inline engines compete with the water cooled engines of WWII?

Perhaps there are no modern engines of those ratings being produced, if that is the case, then could modern air cooled technology produce engines competitive with water cooled engines of WWII?


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## Shortround6 (Oct 29, 2014)

A lot depends on what kind of service life you are expecting, what advantages in metallurgy 60 years may give you and what advantages in foundry work or fin making. 

Some disadvantages of the time that _may_ be hard to get around is that a V-12 air-cooled engine required more space _between_ the cylinders for the fins and airflow than a liquid cooled engine needed. This means a longer, heavier crankcase and crankshaft for starters, it means more problems from torsional vibration. Then you have the cooling problem of the cylinder heads. American radials of the time used a two valve head with widely splayed valves in a hemi style head
with the valves operated by push rods. The liquored cooled engines used four valve heads and overhead cam/s. The more complicated valve gear sucks up space (volume) that the simpler radials used for head fining. 

AS you move from motorcycle/small racecar air cooled cylinders (Early Porsche 917 had cylinders of 375cc while a Merlin had 2250cc cylinders) the ratio of cylinder wall to cylinder volume changes (goes down) meaning each sq in or sq cm of cylinder wall and fins has to get rid of more heat. I would also note that the early Porsche 912 engine (used in the 917 car,confusing?) weighed 540lbs for 580hp at 8,400rpm. 

I am sure they can do better now but lets remember that the_ aircraft _ designer doesn't really care how the engine is cooled and sure doesn't care about the displacement of the engine. He cares about "installed" weight for power and about the total volume of the engine (and airflows) for structure and drag.


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## GrauGeist (Oct 30, 2014)

With modern technology, an engine manufacturer can deliver more bang for the buck today, than was possible back in the late 1930's and early 1940's.

In the automotive world, for comparison, a Ford 49A flathead V-8 of the late 1940's was a real solid performer in it's day, but you compare that to a Chevy 409 of the early 60's, and there's no contest: the 409 was producing over 375 horsepower BUT, it weighed 1,100 pounds. Compare that 409 to a modern V-8 and the 409 comes up woefully short in contrast.

So with the advances in engine performance and technology, the engines of WWII would not be able to compare.


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## Shortround6 (Oct 30, 2014)

all that is true but the Ford 49A flathead V-8 was an up-dated 1931-32 design. The 409 was a hot rodded truck engine.  

High powered aircraft engines were the hi-performance engines of their day. They often had better power to weight ratios than Formula I (or other ) racing car engines of their day (pre war) and for a few years after the war and into the the 1950s. 

Better material have allowed even low-powered air cooled engines to more than double their overhaul life at similar power levels from the 1940s to the 1980/90s so you could probably trade _some_ engine life for higher performance but that only goes so far as the critical limits on air cooling are the head and barrel temperatures. If you 'cook' the oil the engine is going to stop pretty quick no matter what you make it out of. 

In a V-12 you can get 'beam' strength from the crankcase, cylinder blocks and heads. Air cooled engines are going to have separate cylinder barrels even _if_ you can use a common cylinder head (some WW II air cooled engines used seperate barrels and heads and a common cam housing/s which might have added structural strength). Maybe modern material can help with the strength/weight of the construction?


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## tyrodtom (Oct 30, 2014)

A Chevy 409 was a heavy engine, but it didn't remotely weigh 1100 lbs, try about 700 lbs.

Even the old original Chrysle 392 hemis didn't weigh much more than high 700 lbs. range. 

A lot of the performance increases in modern engines come from the electronic controls on fuel injection, spark, and even cam timing.

There's some flathead Ford nut's out there putting electronic fuel injection, etc. on those old flatheads, even they respond with a HP increase. Where the original 239 was 110 hp, there's some modern examples over 250 hp.


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## pbehn (Oct 30, 2014)

At the end of the "Turbo Era" in F1 a 1.5 litre engine was putting out 900 -1000HP in race trim and up to 1300HP in qualifying. Those engines frequently didnt finish a 2 hr race and used some very exotic metals that you may not want in a fighter and the fuels cost a fortune. You cannot up scale BHP by litre, or everyone would be using two stokes but it gives an idea of what is possible. I would say using modern technology a reliable 2000BHP is possible from 10 litres but liquid cooling is a must. Motorcycles produce hi BHP in aircooled engines nowadays (or could do but wouldnt meet noise tests I dont know if the technology would brige the problems of cooling though.


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## Shortround6 (Oct 30, 2014)

There are a couple of problems with comparing race car/motorcycle engines with WW II aircraft engines. 

1. Take modern race car/motorcycle engine to the top of Pikes peak and see how much power it makes. 
2. Take modern race car/motorcycle engine and bolt it to a dyno and run it at full power for *5 minutes*, then drop back to a 20-50% power setting for 5 min and then back to 100% power for *5 minutes* and keep repeating until you get *7 1/2 hours at 100% power*. That was the US standard for WEP ratings. 

I am sure that modern materials and modern heat/surface treatments can improve things quite a bit from the durability stand point but modern race car/motorcycle engines don't run at 100% power for 7 1/2 hours total without a tear down.
Even at Le mans it might be hard for an engine to accumulate more than a few hours at 100% power. 100% power being engine running at it's power peak rpm with throttles wide open. Accelerating up to speed (even 500-600rpm below peak power) with throttle wide open is not 100% power let alone decelerating for corners. 

The original question was also air cooled vs water(liquied) cooled and you still have the heat rejection/dissipation problem. You can _make_ the power, you can get the engine parts not break under the load, _can you keep the engine temperature within limits_ while making that power _and_ can you do it in an installation as small (low drag) and light as a WW II liquid cooled engine. Original question just specified inline engine so X or H 24s ( or more cylinders) could be used instead of limiting to V-12s.


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## pbehn (Oct 30, 2014)

I agree shortround , I was just pointing out how much the peak technology had moved on. Todays technology can produce more power from smaller cylinders and total swept volume. An aircooled design could therefore have fewer and smaller cylinders allowing more space for cooling finning and airflow. I know racing engines are not really comparable to aero engines apart from to show how much things have moved on. Car engines are at peak power much longer than mcycle engines, in a car the power is transferred into down force for much of each lap , for mcycles on some circuits the bike maybe only at peak power in top gear for a few seconds per lap.

Before bikes turned to water cooling the kawasaki 4 cylinder 1000s could produce 100BHP in standard trim and was unburstable. a 24 cyclinder x or H motor based on that is circa 600BHP before any mods/turbo or supercharger is fitted, for a 6 litre. 

I agree with all you say about testing but in F1 for example they were limited to 4 bar on turbo boost, it was rarely the engines that gave way but more likely the turbos constantly changing speed with gear changes and being on the end of some short almost white hot exhausts. Up and down shifting may not be at peak power but puts loads on an engine/gearbox that flying doesnt.


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## Balljoint (Oct 30, 2014)

With materials and electronics either engine could be substantially improved. Keep in mind that “air-cooled” engines reject much, probable most, heat through the oil.

If someone wanted to invest cubic dollars and sacrifice a few engines the Merlin could gain from improved combustion rate (squish and tumble), heat rejection and improved engine controls. The guys who build for Reno are wonderfully crazy but not that crazy. Taken to the ultimate I would think liquid cooled would prevail through better combustion chamber temperature control as in land vehicles.


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## FLYBOYJ (Oct 30, 2014)

Gentlemen, for the record, the only liquid cooled reciprocating *AVIATION *engines being produced today are being manufactured by Rotax and Metalwork, AFAIK. I'm not sure if the latter has a type certificate from any civil aviation authority.


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## gjs238 (Oct 30, 2014)

FLYBOYJ said:


> Gentlemen, for the record, the only liquid cooled reciprocating *AVIATION *engines being produced today are being manufactured by Rotax and Metalwork, AFAIK. I'm not sure if the latter has a type certificate from any civil aviation authority.



How many air cooled manufacturers are still in business (aviation)?


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## Balljoint (Oct 30, 2014)

gjs238 said:


> How many air cooled manufacturers are still in business (aviation)?



And when were they designed?


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## Shortround6 (Oct 30, 2014)

Not modern technology by any means but what was going on in the 1930s see: http://www.ww2aircraft.net/forum/aviation/liquid-cooled-napier-dagger-37091-2.html

The Napier Dagger was an air cooled 24 cylinder engine;

Type: Twenty-four-cylinder supercharged air-cooled H engine
Bore: 3.813 in (96.8 mm)
Stroke: 3.75 in (95.25 mm)
Displacement: 1,027 in³ (16.8 L)
Length: 80 in (2,032 mm)
Width: 22.5 in (584 mm)
Height: 45.125 in (1,146 mm)
Dry weight: 1,358 lb (616 kg)







That gave about 1000hp at 4200rpm at 8750ft using 6lbs of boosst (?), it had cooling problems (supposedly solvable with different ducts/outlets). 

Now with modern practice we might get the rpm up to 4800rpm or even higher (and even a 20% increase gives you 5040rpm) and still keep reasonable piston speeds. Again aircraft engines have to run at their upper rpm limit for several minutes at a time, not seconds. Modern valves and valve springs should have no problem at this rpm. Going to 4 valve heads should improve power but how much considering the engine is already supercharged? 

engine at 16.8 liters is already as long, higher but narrower and just as heavy (but needing no radiators/coolant) as a 27 liter Merlin or 28 liter Allison. It is going to need to turn at 4800 rpm or better to move as much air. 
Better casting/forging/machining of fins (or bonded sheet metal fins ?) can help cylinder cooling, longer valve stems might allow cam boxes to be spaced further from heads for more fins area/airflow for heads (at the cost of more bulk and weight), more oil spray on piston bottoms may help ( bigger oil cooler). 

Now to compete with late war V-12 liquid cooled engines the air-cooled engine has to make 1500-1750hp. It also has to run at 75-80% power for hours (tens of hours) on end (not 5 minutes spurts). 

Can you improve the cooling enough to handle the extra heat transfer without a major increase in weight and bulk, we can assume the the actual engine strength and ability to make the power are a given considering better materials/alloys and better understanding of gas flows through manifolds, heads and valves and fuels, etc. 
Note that using the same fuel the Merlin gave almost the same _net_ power about 8000 ft higher in thinner air and using more of it's 'gross' power to drive the supercharger at a cost of around 300lbs more in radiator and coolant. 

and again with aircraft, at 20,000ft to get the cooling you want you need xxx pounds or kilograms of air through the fins per minute and at 20,000 ft that means a lot more cubic ft (or cubic meters) to get the same _mass_ of air. Granted it is colder but you only have micro seconds to make the heat transfer.


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## FLYBOYJ (Oct 30, 2014)

gjs238 said:


> How many air cooled manufacturers are still in business (aviation)?



Quite a few - off the top of my head, Lycoming, Continental, Rotax, Harbin, PZL, Verner, I know there are more.


Balljoint said:


> And when were they designed?



Some recent, some 70 years ago...


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## GrauGeist (Oct 30, 2014)

An example of an air-cooled V-12 from WWII would be the Argus As410 and As411, both used in a variety of Luftwaffe aircraft.

The Argus As411 was manufactured after WWII under Renault/SNECMA as the 12T.

Other aircooled V-12s of the WWII era were the Ranger V-770, Isotta-Fraschini Delta series, de Havilland Gipsy "Twelve".


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## gjs238 (Oct 30, 2014)

If power levels were high enough, and evidently they were not, air cooled would seem to be a great benefit for extremely cold conditions.
How many Allied Axis engines froze?


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## GregP (Oct 31, 2014)

We're overhauling an Argus AS-10 inverted V-8 right now for our Fieseler Storch at the Planes of Fame. It is progressing nicely.

Modern piston engines are not MADE for aviation in anywhere NEAR the power levels that were being flown every day in WWII.

If the modern guys scaled up, they might do better and might not ... they have forgotten a LOT of tribal knowledge about large piston engines because they aren't made and have't been made for 50+ years. Go look at an Allison V-1710 or a Merlin 1650 V-12. 4 valves per cylinder and made very close to 1 HP per cubic inch or 61.02 Hp per liter and better.

Yes there are modern engines out there that make that power level, but do they do it like an aviation engine? Like maybe 100% power for takeoff and climb (say 15 - 20 minutes) and then 60 - 75% power for another 5 - 8 hours, and do it every other day or so for 400+ hours, and do it efficiently at 25,000 feet? Maybe four at a time as in a 4-engine bomber? And continue to run with bullet holes in the crankcase? With maintenance out in the open on an airfield that was recently a farmer's field, complete with rain, dust, bugs, birds, and everything else?

I could throw a handful of sand into the intake of ANY Formula 1 car and it would expire in less than 10 minutes. The big engines of WWII ate dust for months between overhauls. Ask ANYONE who flew from, say, Malta or in North Africa. I have and they ran just fine for longer than anticipated. 

I can't think of even ONE modern engine that could do it except maybe a diesel ... and they were NOT the engines of choice in WWII. The ONLY reason we are flirting with diesels in aviation today is the cost of fuel. If it weren't that, nobody would bother with them at all except in trucks hauling freight and large boats and ships. They are good for good torque at low RPM at one speed for a long time ... hardly an aviation need.

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## GrauGeist (Oct 31, 2014)

gjs238 said:


> If power levels were high enough, and evidently they were not, air cooled would seem to be a great benefit for extremely cold conditions.
> How many Allied Axis engines froze?


None of the aircraft engines, air-cooled or water-cooled, liked sub-zero temps. Without pre-heating, they wouldn't operate.

Fw190 on the Eastern Front





A-20 in Alaska





P-40 in Alaska

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## GregP (Oct 31, 2014)

Great pics, Graugeist!

Thanks!

I was gonna' like this post but can't seem to find the means to do it ... the like/nacon stuff disappeared on my PC ... WTF?


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## pbehn (Oct 31, 2014)

GregP said:


> If the modern guys scaled up, they might do better and might not ... they have forgotten a LOT of tribal knowledge about large piston engines because they aren't made and have't been made for 50+ years. Go look at an Allison V-1710 or a Merlin 1650 V-12. 4 valves per cylinder and made very close to 1 HP per cubic inch or 61.02 Hp per liter and better.
> 
> I can't think of even ONE modern engine that could do it except maybe a diesel ... and they were NOT the engines of choice in WWII. The ONLY reason we are flirting with diesels in aviation today is the cost of fuel. If it weren't that, nobody would bother with them at all except in trucks hauling freight and large boats and ships. They are good for good torque at low RPM at one speed for a long time ... hardly an aviation need.



Greg I think they easily could if they wanted to, but who would want to, getting an engine approved is an arduous process I believe, if you want to do 500MPH in a plane just buy a jet. Diesels only good for freight boats and ships? WAAAAAAH my Audi is a diesel actually its just as fast as the petrol version (governed to 155MPH) 0.1 sec slower to 60MPH but way better on economy....especially at 90/100MPH the normal cruising speed here.


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## gjs238 (Oct 31, 2014)

GregP said:


> The big engines of WWII ate dust for months between overhauls. Ask ANYONE who flew from, say, Malta or in North Africa. I have and they ran just fine for longer than anticipated.



Some Hurricanes were "tropicalised" with Vokes air filters to deal with certain environments.

From Wikipedia:
_Hurricane Mk IIB Trop.
For use in North Africa the Hawker Hurricane Mk IIB (and other variants) were tropicalised. They were fitted with Vokes and Rolls Royce engine dust filters and the pilots were issued with a desert survival kit, including a bottle of water behind the cockpit.[102]_



GregP said:


> I can't think of even ONE modern engine that could do it except maybe a diesel ... and they were NOT the engines of choice in WWII. The ONLY reason we are flirting with diesels in aviation today is the cost of fuel. If it weren't that, nobody would bother with them at all except in trucks hauling freight and large boats and ships. They are good for good torque at low RPM at one speed for a long time ... hardly an aviation need.



There was some brief use of diesels in aircraft in the early 1900's.
Even radial diesels.
https://en.wikipedia.org/wiki/Category:Aircraft_diesel_engines

Several aircraft used diesels, a famous one is the Junkers Ju 86
https://en.wikipedia.org/wiki/Junkers_Ju_86


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## pbehn (Oct 31, 2014)

GregP said:


> If the modern guys scaled up, they might do better and might not ... they have forgotten a LOT of tribal knowledge about large piston engines because they aren't made and have't been made for 50+ years. Go look at an Allison V-1710 or a Merlin 1650 V-12. 4 valves per cylinder and made very close to 1 HP per cubic inch or 61.02 Hp per liter and better.
> 
> Yes there are modern engines out there that make that power level, but do they do it like an aviation engine? Like maybe 100% power for takeoff and climb (say 15 - 20 minutes) and then 60 - 75% power for another 5 - 8 hours, and do it every other day or so for 400+ hours, and do it efficiently at 25,000 feet? Maybe four at a time as in a 4-engine bomber? And continue to run with bullet holes in the crankcase? With maintenance out in the open on an airfield that was recently a farmer's field, complete with rain, dust, bugs, birds, and everything else?
> 
> I could throw a handful of sand into the intake of ANY Formula 1 car and it would expire in less than 10 minutes. The big engines of WWII ate dust for months between overhauls. Ask ANYONE who flew from, say, Malta or in North Africa. I have and they ran just fine for longer than anticipated.


Greg Ive been thinking about this a little. In racing the engine just has to last to the end of the race the maximum power is therefor pretty much that. For an Aero engine it must last for the cycles you say and hold together. The maximum power is therefore not the maximum possible but the maximum certified to be used. Reading about engines there is frequently a remark somewhere that so and so engine produced 4,000 or 5,000HP on a test bed. They never say how long it held together and no one pretends it would be safe to run it in an AC at that power.


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## Shortround6 (Oct 31, 2014)

pbehn said:


> In racing the engine just has to last to the end of the race the maximum power is therefor pretty much that. For an Aero engine it must last for the cycles you say and hold together. The maximum power is therefore not the maximum possible but the maximum certified to be used.



In car racing or motorcycle racing if the engine blows up you can walk back to the pits (danger is from other drivers/vehicles). In Hydroplane racing you can float around waiting for the tow boat. Blow up the engine in an airplane and ?????????


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## GregP (Oct 31, 2014)

Let's put this into perspective.

Nobody has made a 1500 - 2500 HP aero piston engine in about 70 years. The last ones that were liquied cooled displaced 1649 and 1710 cubic inches and made 1,850 - 2,200 HP reliably for 400+ hours between overhauls. The bearing technology has been lost and NOBODY is making steel mains with silver pressed into the steel and lead pressed into the silver. These are the bearings that lasted 400+ hours at high power levels ... no longer made and haven't been made for 70+ years.

Call me a doubter but I don't think anybody can make an engine that is as good a Merlin or an Allison today without suffering an entire rash of failures due to all the tribal knowledge about large piston engines that has been lost except for a few qualified overhaulers.

Just my opinion. Yours may vary and that's OK.

Yes they had a few aerial diesels, such as the Blohm und Voss BV.139's engines. None were of the high-performance variety and they STILL don't have a great diesel for general aviation aircraft today. So I very seriously doubt the claim about it being easy to make an aerial diesel. If it's so easy, where ARE they? We've been asking for them for abouit 20 years now and they are a VERY conspicuous no-show. The ones flying don;t even have a TBO! They have a TBR ... time between repalcement!


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## gjs238 (Oct 31, 2014)

GregP said:


> Let's put this into perspective.
> 
> Nobody has made a 150 - 2500 HP aero piston engine in about 70 years. *The last ones that were liquied cooled displaced 1649 and 1710 cubic inches* and made 1,850 - 2,200 HP reliably for 400+ hours between overhauls.



1710?


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## GrauGeist (Oct 31, 2014)

Here's some typical engines used in a variety of warplanes, certainly not the largest engines of the war, but does give an idea of how big those engines were on average:

Rolls-Royce Merlin 61: 1,647 CID (27L)
Allison V-1710-F30R: 1,710 CID (28.02L)
Daimler-Benz DB601A: 2,070.5 CID (33.93L)
Junkers Jumo 213E: 2,135.2 CID (35L)
Klimov VK-107A: 2,140 CID (35.08L)
Mikulin AM-35A: 2,847 CID (46.66L)


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## gjs238 (Oct 31, 2014)

I was thinking of the DB 603A at 44.52 L (2,716.9 in3)


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## GregP (Oct 31, 2014)

The German and Soviet engines were not designed with the same fuel in mind as the Merlin and Allison were. Less energetic fuel means more cubic inches for the same power. Nothing WRONG with displacement, but better fuel renders smaller engine displacement with equivalent or better power. 

I'm sure that had the Soviets had access to 150 octane fuel, their engines would have gained power or lost dispalcement or both. Nothing wrong with the existing engines since they often ran on fuel that was heavily contaminated and was strained through chamois or even bedsheets anf field jackets! I have a few Russian friends that have related stories about winter flying in the Soviet Union that would certainly make you glad you weren't there ... or wish you weren't if you WERE there.

The German engines were superb and really didn;t need much help. Nothing wrong with a DB or a Jumo except maybe the general lack of electric starters in the field.


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## GrauGeist (Oct 31, 2014)

Like I said, those were average sizes and look at how they performed in the aircraft they were installed in.

There were much larger engines that were in use (this does not include prototypes or dead end projects):

Rolls-Royce Vulture V: 2,592 CID (42.47L)
Junkers Jumo 222A: 2,830 CID (46.5L)
Mikulin AM-42: 2,847 CID (46.66L)
Allison V-3420-A18R: 3,420 CID (56L)


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## GregP (Nov 1, 2014)

I'm SURE you KNOW that the Allison 3420 was just two 1710's ona common crankcase. They were V-1710-based.

They only made 538 Vultures and they were unsuccessful. I never considered them and they were abaondoned early in the war.

The AM-42 started out in life as the AM-34, designed in Italy, and morphed into the AM-35, then the AM-38 and, finally, the AM-42. It had some Soviet input in that time, naturally, but was a larger-displacement engine than the MNerlin or the Allison ... alrgely due to les sophisticated fuel used in development and operation. It had the very unique characteristic of having a longer stroke on one side than the other due to articulated connecting rods on one side!

My entire point is nobody has made large HP or large-displacement piston aero engines in a LONG time. So there has been a very large loss of knowledge about how to do it. What is your point? No argument, just curious as to what direction your comments are leading. I agree with them, but they don't address my contention and I was just wondering.


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## GrauGeist (Nov 1, 2014)

GregP said:


> I'm SURE you KNOW that the Allison 3420 was just two 1710's ona common crankcase. They were V-1710-based.
> 
> They only made 538 Vultures and they were unsuccessful. I never considered them and they were abaondoned early in the war.
> 
> ...


But those engines I listed were used in types, even if they weren't long-term production airframes.

The point is, gjs238 wanted to see bigass engines and so a list was put forth that delivered. Like I mentioned in the previous thread, the bigass engine list was not prototypes or dead-ends, but ones that actually saw service. There were much larger ones that were being fooled around with, but failed to materialize for one reason or another.

If we want to talk serious ass-kicking horsepower and cubic inches, we could talk Dragster engines. Pound for pound, these are technically the most powerful powerplants on earth...
_
* Even with nearly 3000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into nearly-solid form before ignition. Cylinders run on the verge of hydraulic lock.

* Under full throttle, a dragster engine consumes 1 1/2 gallons of nitro per second, the same rate of fuel consumption as a fully loaded 747 but with 4 times the energy volume.

* Dual magnetos apply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.

* At stoichiometric (exact) 1.7:1 air/fuel mixture (for nitro), the flame front of nitromethane measures 7050 degrees F.

* Nitromethane burns yellow. The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

* Spark plug electrodes are totally consumed during a pass. After 1/2 way, the engine is dieseling from compression-plus the glow of exhaust valves at 1400 degrees F. The engine can only be shut down by cutting off its fuel flow.

* If spark momentarily fails early in the run, unburned nitro builds up in those cylinders and then explodes with a force that can blow cylinder heads off the block in pieces or blow the block in half.

* Dragsters twist the crank (torsionally) so far (20 degrees in the big end of the track) that sometimes cam lobes are ground offset from front to rear to re-phase the valve timing somewhere closer to synchronization with the pistons.

* Nitromethane-powered engines of NHRA Top Fuel dragsters and Funny Cars produce approximately 7,000 horsepower, about 37 times that of the average street car._

Now how about that technology in a warbird?


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## GregP (Nov 1, 2014)

AA Fueler Dragster engines run about 10 - 12 seconds max. About halfway down the dragstrip the spark plugs are burned away and it is dieseling. They wouldn't last as long as a takeoff run for Piper Cherokee 180. I have never considered them to be anything but dragster engines and won't. But I DO love to watch them run. The WinterNationals will be soon at Pomona Raceway and I'll BE there. In addition to the dragsters, they will have a cacklefest, too. Don Garlits, Don Prudhome, and a lot of others will be there with cars from the past that start and run. Maybe they'll be allowed to do some slow runs ... if they stay under 200 mph or so.

If someone asked for a list of engines, then go for it.

I still say NOBODY could build a large-displacement, 1500 - 2500 HP, liquid-cooled piston aero engine today without a LOT of development. They have just lost the formula and would need to rediscover it. What is needed is GREAT power at LOW rpm ... depending on propeller diameter. Can't design one without the other unless you are resigned to a PSRU, and most WWII engines WERE geared except for some smaller radials that had both geared and direct drive units produced. They were NOT the power champs.

An engine is nothing more than a big air pump and direct drive engines will always pump less air than a geared unit of the same displacement.


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## GrauGeist (Nov 1, 2014)

I had a GM 702.9 CID V-12 in my '68 Chevelle that was a real ass-kicker...

The 702 engine was about 1958 vintage and ran like a beast...plus it was a real head turner at the show and shines back in the 80's 

Big cubes had their place in the sun at one time...


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## tyrodtom (Nov 1, 2014)

GrauGeist said:


> I had a GM 702.9 CID V-12 in my '68 Chevelle that was a real ass-kicker...
> 
> The 702 engine was about 1958 vintage and ran like a beast...plus it was a real head turner at the show and shines back in the 80's
> 
> Big cubes had their place in the sun at one time...



I can remember some of the bigger coal trucks around here having those in the late 50's early 60's.
They looked like 2 V-6's welded together because of the 2 rocker arm covers on each side, but it was actually one big cylinder block.

They were the king of the haulers until the diesels started taking over.

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## swampyankee (Nov 1, 2014)

gjs238 said:


> Can modern air cooled inline engines compete with the water cooled engines of WWII?
> 
> Perhaps there are no modern engines of those ratings being produced, if that is the case, then could modern air cooled technology produce engines competitive with water cooled engines of WWII?



Cooling air-cooled inlines was difficult. Sometimes it was done successfully, but it required more care than cooling air-cooled radials, with no drag advantage (the drag advantage of liquid-cooled vs air-cooled engines is largely illusory, although it was, and is, easier to design a aircraft engine installation when there's an intermediate liquid heat transfer loop than when their isn't. Negative cooling drag is possible with both, but rarely achieved with either.)

Air-cooled engines clearly could be produced to compete with liquid-cooled engines in WW2, although only one really large air-cooled V-12 saw any kind of service, the Isotta Fraschini Delta. The big air-cooled engines were all radials. This wasn't accidental: radials are lighter than in-lines of the same capacity.


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## GrauGeist (Nov 1, 2014)

tyrodtom said:


> They looked like 2 V-6's welded together because of the 2 rocker arm covers on each side, but it was actually one big cylinder block.


Yep!

Highly unusual for a street rod but sure drew a crowd wherever we parked. And torque, lots of torque! 

Here's an info-graphic from back in the day, for those that might be interested...








And now, we return to the regularly scheduled aircraft engine talk!

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## gjs238 (Nov 1, 2014)

Awesome, all set for installation in aircraft.
Even has a propellor attached.


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## GrauGeist (Nov 1, 2014)

Actually, there is a good number of automotive engines that have found their way into aircraft over the years.

Some examples would be the Chevrolet H-6 aircooled engine (best known for it's use in the Corvair automobile), Volkswagon's Type I H-4 aircooled engine amongst others...


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## Shortround6 (Nov 1, 2014)

I have read (but don't know it it's true) that one reason that nobody is using silver bearings on modern engines is that some of the anti-scuff additives in many modern motor oils attack and corrode the silver in the bearings leaving them in rather poor condition after a while. Modern oils work well with modern bearings, Not so good using modern oil with old bearings or old specification oil with new bearings. The modern bearings depending, in part, on the additives in the oil.


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## pbehn (Nov 1, 2014)

An engine could be constructed air or water cooled, 2 or 4 stroke but who would make it it would in F1 terms require a team working for 5 years to produce it that is about 300 milion dollars for the first flight, just to prove a principle. If any one wants a high performance prop SE aircraft use a turbine.. Problem is with the sound and lack of WW2 connection.


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## tomo pauk (Nov 1, 2014)

GregP said:


> ...
> The AM-42 started out in life as the AM-34, designed in Italy, and morphed into the AM-35, then the AM-38 and, finally, the AM-42. It had some Soviet input in that time, naturally, but was a larger-displacement engine than the MNerlin or the Allison ... alrgely due to les sophisticated fuel used in development and operation. It had the very unique characteristic of having a longer stroke on one side than the other due to articulated connecting rods on one side!
> ...



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.


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## wuzak (Nov 1, 2014)

GrauGeist said:


> Here's some typical engines used in a variety of warplanes, certainly not the largest engines of the war, but does give an idea of how big those engines were on average:
> 
> Rolls-Royce Merlin 61: 1,647 CID (27L)
> Allison V-1710-F30R: 1,710 CID (28.02L)
> ...





gjs238 said:


> I was thinking of the DB 603A at 44.52 L (2,716.9 in3)





GrauGeist said:


> Like I said, those were average sizes and look at how they performed in the aircraft they were installed in.
> 
> There were much larger engines that were in use (this does not include prototypes or dead end projects):
> 
> ...



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)


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## Shortround6 (Nov 1, 2014)

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.


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## pbehn (Nov 1, 2014)

GregP said:


> AA Fueler Dragster engines run about 10 - 12 seconds max. About halfway down the dragstrip the spark plugs are burned away and it is dieseling. They wouldn't last as long as a takeoff run for Piper Cherokee 180. I have never considered them to be anything but dragster engines and won't. But I DO love to watch them run. The WinterNationals will be soon at Pomona Raceway and I'll BE there. In addition to the dragsters, they will have a cacklefest, too. Don Garlits, Don Prudhome, and a lot of others will be there with cars from the past that start and run. Maybe they'll be allowed to do some slow runs ... if they stay under 200 mph or so.
> 
> If someone asked for a list of engines, then go for it.
> 
> ...



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.


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## pbehn (Nov 1, 2014)

tomo pauk said:


> 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.



The lancasters that bombed the Tirpitz from Russia ran like dogs on Russian fuel.


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## GregP (Nov 1, 2014)

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.


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## tomo pauk (Nov 2, 2014)

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“ÐÐ¦ Ð*Ð¤ Ð¤Ð“Ð£ÐŸ "ÐÐÐœÐ˜"), an institution that oversaw engine development.


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## Piper106 (Nov 2, 2014)

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.


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## Shortround6 (Nov 2, 2014)

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.


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## Koopernic (Nov 7, 2014)

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.


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## tomo pauk (Nov 7, 2014)

Koopernic said:


> 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 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. 



> Had the two techniques been combined I believe we would have radial engines beating water cooled engines.



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.



> 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.
> ...



Plus the Bf-109F-4, Gustavs prior the G-6 (even without Notleistung ), the P-51A.


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## Shortround6 (Nov 7, 2014)

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.


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## swampyankee (Nov 9, 2014)

Piper106 said:


> 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.
> 
> ...



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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## gjs238 (Nov 9, 2014)

swampyankee said:


> it had a variable compression ration, achieved by hydraulically varying the length of the connecting rods.



Never heard of that - neat idea.


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## Shortround6 (Nov 9, 2014)

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?

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## gjs238 (Nov 10, 2014)

Wonder if this is why diesel automobiles are so popular in Europe?
Ideal if the public and the military can share fuel.


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## Shortround6 (Nov 10, 2014)

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.


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## tomo pauk (Nov 10, 2014)

gjs238 said:


> Wonder if this is why diesel automobiles are so popular in Europe?
> Ideal if the public and the military can share fuel.





Shortround6 said:


> Might be very indirect. Like if there are policies on taxes on diesel fuel vs gasoline or something.



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.


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## Shortround6 (Nov 10, 2014)

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.


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## swampyankee (Nov 10, 2014)

Shortround6 said:


> 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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## pbehn (Nov 10, 2014)

Shortround6 said:


> 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.



SR try living in Europe Diesel as a product is cheapest in UK but the UK applies the highest amount of tax so to buy UK diesel is most expensive. More than haf the cost of diesel and petrol is tax here so it just bears as much relation to the oil price as the governments wants. I dont know what the governments latest idea is before I set off to go to Germany through France Belgium and Holland .


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## pbehn (Nov 10, 2014)

At the end of the war Rolls Royce were working hard on the Crecy a supercharged 2 stroke maybe that would have been the future but it must have been deafening.


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## Shortround6 (Nov 10, 2014)

I know we have it easier here in the US, the point I was trying to make was that If I buy the gas Jetta ( or pick some other cars) I can drive for 30-35,000 miles before my cost of car+fuel equals the price of Diesel Jetta and driving it home from the dealer. If you are not a high mileage driver it could be two years before you _start_ to get past the break even point. This has got to affect the popularity of some diesel cars. And as I pointed out, I am about 100 miles from one of other members living on opposite sides of NY City yet I would pay 15% more diesel fuel than he would. I would also pay more for Diesel than for premium let alone regular fuel so it would take me years to start saving money with the diesel. 
The government has or had _some_ tax incentives for hybrid cars but none for diesels.


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## GrauGeist (Nov 10, 2014)

pbehn said:


> SR try living in Europe Diesel as a product is cheapest in UK but the UK applies the highest amount of tax so to buy UK diesel is most expensive. More than haf the cost of diesel and petrol is tax here so it just bears as much relation to the oil price as the governments wants. I dont know what the governments latest idea is before I set off to go to Germany through France Belgium and Holland .


Gasoline prices weren't bad in Bulgaria, Croatia or Serbia, a little higher in Slovenia but they were completely ridiculous in Greece and parts of Italy.

That was about the only negative thing I encountered during my trip (summer of 2012) besides the endless toll booths in Greece (and the tolls were NOT cheap)


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## Koopernic (Nov 17, 2014)

tomo pauk said:


> 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 P-51A or Mustang I AFAIKT ever exceeded 390mph though with the Allison replaced with a Merlin 45 or better still Merlin 28 it surely would have.
The XP38J surely represents a post war aircraft as it used a never quite developed V16 engine.

The Focke-Wulf Ta 152 might have been seen with the Jumo 222E/F engine. This engine was benching 2800hp with B3+MW50 with two stage multispeed supercharger and surely would have managed an easy 3100hp on better fuel and a speed in excess of 500mph. The Jumo 222A2/B2 was scheduled for production for September 1944 but I think air-cooled engines would have matched in (eg XP-72 superbolt).

It just depends on what engine was in development at the right time, just before piston development was shut down in favour of jets.


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## tomo pauk (Nov 17, 2014)

Koopernic said:


> The P-51A or Mustang I AFAIKT ever exceeded 390mph though with the Allison replaced with a Merlin 45 or better still Merlin 28 it surely would have.



P-51A (V-1710 F20R engine, 1125 HP at 14500 ft without ram) was called the Mustang II, in service abroad from September 1943. One of the tests:link.
Not to be confused with Mustang I (V-1710 F3R engine, 1150 HP at 12000 ft without ram), in service with RAF from April 1942. 



> The XP38J surely represents a post war aircraft as it used a never quite developed V16 engine.



I was talking about the XP-*47*J (Thunderbolt), not the XP-*38*J (Lightning). The engine in the XP-47J was the R-2800 'C' series, fan cooled installation.


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