Which country designed the best engines for WWII?

Calum - many thanks.
Granted, I look forward to see your book.

wuzak said:

The Sabre pushed the rpm envelope before the 213 did. But it had much less piston speed.

Click to expand...

Nothing wrong with being oversquare. Somewhere I read that the Sabre's throttle could be "blipped" like a motorcycle.

Designing an engine so technically and metallurgically complicated it was unlikely to see service for a decade or more yet in 1945 was already obsolete is hardly the work of a great designer. A great design is one that is able to be manufactured on a production line and be in service when needed. Otherwise its just a future technology demonstrator like the shiny concept cars you see on display at major motorshows which never ever seem to quite make it on sale. I am still waiting patiently after 50 years for my flying car.

The Heck with flying, I am still waiting for my turbine powered car I could run on peanut oil.

Shortround6 said:

The Heck with flying, I am still waiting for my turbine powered car I could run on peanut oil.

Click to expand...

Maybe you could satisfy your gas turbine vehicle ambitions by picking up one of these surplus:

fastmongrel said:

Designing an engine so technically and metallurgically complicated it was unlikely to see service for a decade or more yet in 1945 was already obsolete is hardly the work of a great designer.

Click to expand...

Did Rube Goldberg work for Napier?

Rube Goldberg's nephew didn't show up at Napiers until after the war.

The Sabre was one of Frank Halford's brainchildren; he did have a tendency to introduce complication into his designs, although he was also responsible for one of the simplest and most widespread aero engine designs pre-WW2 that existed; the upright and subsequently inverted four cylinder engine variously known as the Airdisco/Blackburn Cirrus and the DH Gipsy, based simply by cutting a war surplus Renault Vee 8 in half.

wuzak said:

The Merlin Beaufighter was built in case there was a shortage of Hercules, and the Lancaster II was built in case of a shortage of Merlins.

Click to expand...

Yep, and the Merlin Beaufighter had a terrible reputation for handling and contributed to delays in getting the Beau night fighter into service later than anticipated. One pilot recounted that he considered the Beaufighter II's handling as 'pure evil'. Mind you, most of the British night fighter pilots had seen service in Blenheims and Defiants, both of which had docile handling.

The unfavourable installation of the Merlin in the Halifax and consequently the Hercules in the Lancaster was to do with location of the engine in line with the wing chord. The Lanc's Merlin was suspended below the chordline, its thrust line being below the wing, whereas the Halifaxes' engine's thrust line was located closer to the chordline, which was suitable with the Hercules, but caused airflow disruption with the Merlin. The Merlins were also canted slightly upwards on the Hali. Handley Page had a raft of difficulties with its Merlin installation, from oil coolers to exhaust ports and drag issues and it took considerable effort from HP and Rolls to sort out, but most of these were never cured and fitting the Hercules in place of the Merlin seemed the best method of getting rid of the problems that wouldn't go away.

gjs238 said:

Maybe you could satisfy your gas turbine vehicle ambitions by picking up one of these surplus:

Click to expand...

Be good fun to own one, no parking problems for a start but you would need your own Oil refinery to keep the fuel tank full

Snowygrouch said:

Germany:

Germany conducted the most in depth research on almost every single engine system.
I can state that I believe their supercharging work is stunningly good (see attached pic SC), and were the only ones
towards the end who started developing engines which were on the truly modern path philosophically,
of radically increasing crankshaft speeds, and having flexible valve timing controls; which with the
possibilities of direct injection are really knocking on the door of all modern engines, in terms
of control possibilities.

However they utterly failed in the task of taking all this research and putting it into one, or two
engines which would actually be able to be mass manufactured in time to have any useful
war impact.

Click to expand...

And, in that second paragraph, is the rub (to misquote the bard). It's also why in practical terms I'd rank Germany behind both the major western Allies. I'm not qualified to make a judgement on the others or Japan.

When Cairncross visited German aircraft factories in July 1945 he wrote this.

"I found that the German designers were puzzled how our [British] fighters had always managed to produce the extra power to stay ahead of theirs. Practically all our fighters had Rolls Royce Merlin engines and Rolls had found ways of modifying the Merlin on the production line, with or without a change in Mark number, to yield more and more engine thrust while their opposite numbers at say BMW (Bayerische Motorenwerke) had relied on discontinuous changes in specification as one mark of engine replaced another on the production line. Thus the Germans improved performance in jumps and did not have the benefit of an engine as capable as the Merlin of further development, any lead established in one of those jumps did not last long."

Now this is a systemic rather than technical difference, and does support your contention about the relative complexities of British and German engines generally. When there is a war to be fought getting the best out of what you have, particularly if that can keep you for the most part ahead of the curve, is almost literally a matter of life and death. In this the Germans patently failed. Producing a few technically superior developmental engines, as the Germans certainly did, is of little use when there is a war to fight, it is more important to get the best engines possible into mass production and keep them there until any useful development potential has been utilised. This makes the Rolls Royce Merlin a better engine than anything mass produced by the Germans.

Cheers

Steve

Shooter8 said:

All most any current Turbo-Diesel will run on "Peanut Oil" and the Turbine in the Turbo-Charger is a very large part of the engine's personality and performance!

Click to expand...

You do realize that SR's comment and the car posted have nothing to do with a turbo-diesel?

That's a Chrysler TURBINE automobile pictured, powered by a Chrysler A831 gas turbine engine instead of a piston engine.

The DB 603, 605 and Ju 213 are examples of exactly the issue the Germans were having, as explained by Cairncross.

Take the Jumo 213, 9163 built, according to Vajda and Dancey, in almost three years! That is similar to just three months UK production of the Merlin, not even counting US production. The DB 603, 8758 built. These are trifling numbers.
Only the DB 605 was produced in meaningful numbers, 42400 or 45222 depending who you believe, and it was an important engine. It was built in a confusing variety of types, but then the Germans had a history of this, there were more than 30 versions of the DB 601!

This also demonstrates the point of 'snowygrouch's' excellent post, when he wrote of the German aero-engine industry,

"However they utterly failed in the task of taking all this research and putting it into one, or two
engines which would actually be able to be mass manufactured in time to have any useful
war impact."

In 1945 Jumo were working on the Jumo 213, 222 and 225. They were also working on various diesel engines, the Jumo 250/207, 206/208 and 223/224. In addition they were developing or working on no less than 12 different propellers.
The company was also working on the KM 8, a torpedo motor, and of course various jet projects, including various versions of the Jumo 004 and the Jumo 012, 022 (turboprop).

Daimler Benz were also committed to various projects like the DB 630 and DB 021 (turboprop).

With the one exception of the Jumo 004 none of these engines were of any use to the war effort, nor in a meaningful way, were the Ju 213 or DB 603.


The Merlin was a better wartime engine because it was capable of continual development with minimal impact on total production (because of the way Rolls Royce was organised) in such away that it was never left behind by German developments for any length of time. What is notable in Cairncross' account is that the Germans had no idea how the Anglo-Americans had managed to do this.

Cheers

Steve

stona said:

What is notable in Cairncross' account is that the Germans had no idea how the Anglo-Americans had managed to do this.

Click to expand...

Fuel.
The Germans must have known of advances in Allied fuel.

gjs238 said:

Fuel.
The Germans must have known of advances in Allied fuel.

Click to expand...

Without wanting open a very wriggly can of worms again German fuel scientists produced fuel that was no better or worse than Allied fuel scientists. Just because the Hydrocarbons came from Coal not Oil doesnt mean German fuel was worse.

gjs238 said:

Fuel.
The Germans must have known of advances in Allied fuel.

Click to expand...

It was the rolling development of engines, particularly the Merlin, that dumbfounded the Germans.

Rolls Royce was organised in a three tier system. At the top was RR Derby, the parent company, below that RR Crewe and then on the third level three plants, RR Glasgow, Ford Manchester and Packard in the USA.
In Hives words the parent Derby factory was

"a huge development factory rather than a manufacturing plant."

The Glasgow, Ford and Packard factories were planned for mass production from the outset. Crewe was in an intermediate position and although it was better suited to mass production than Derby, flexibility remained an important consideration. This did restrict Crewe's productivity but it augmented Derby's output of the very latest engines. Crucially the British accepted some loss of production at Derby and to a lesser extent Crewe in order to implement a continuous development of the Merlin. This was the point that Cairncross was making when comparing the continuous development of the Merlin to the incremental jumps in the development of German engines.

Rolls Royce knew that the Merlin was capable of development. In 1938 Rolls Royce was able to concentrate on Merlin production, but was worried that ultimately other types might have to be built alongside it.
Hives wrote

"We could not at the present time take on a production order for Exe engines... It looks as though it is certain we shall be producing Merlins and Vultures in paralell, and very possibly Prergrines... It means we have got to seriously reconsider our production facilities."

One month later, in April, he re-iterated

"...to have three types running concurrently will introduce quite a lot of difficulties."

Rolls Royce pushed hard to limit production to a standard engine, something the Germans with their complicated and highly personalised and politicised system could never have done. Just over a year later, in June 1939, as the war loomed, Hives was writing in a policy document.

"Our proposal is that it should be a definite policy of the Air Ministry that the plant for producing the standard engine, which in our case is the Merlin, should not be broken down to produce another type."

There is more to a good engine in wartime than just the nuts and bolts.

Cheers

Steve

The fuel situation is central to the development history of a number of engines if not to engine development in general. But that development history starts back in the early 30s at the very least.
Since it can take four years or so to bring an engine from drawing board to production (or longer) having a crystal ball that informs the designer what fuel will be available 4 years in the future and in what quantities or costs would have been a very handy thing to have.
Once a designer (or design team) starts down a certain path it is very hard to change paths (start over) without losing 1-3 years of work.
With a given quality of fuel there are only a few paths to power. Since the volume ratio of liquid fuel to air is around 9000 to 1 getting air into and out of the engine (air pump) is the primary goal. Power to weight is the main criteria for aircraft engines. so for a given weight of engine you have pretty much 3 paths. A lightly stressed (low parts weight) large displacement engine turning low rpm. A very attractive option but leaves something to be desired for future development. A moderate to high stress (high parts weight) engine turning high rpm. Or a high weight complex engine using more than the normal/common number of cylinders using very high rpm but lower stress due to the small size of the parts.
All three options would be using about the internal cylinder pressures if using the same fuel.

The first option was one widely chosen by a number of engine designers/teams as it posed the fewest risks. When Howard Hughes set a world speed record in 1935 using 100 octane gasoline the 100 octane gasoline cost $4.00 a gallon or over 10 times what normal aviation fuel costs. People knew 100 octane fuel was coming, they didn't know when. 2 years or 6 years? Or....???? Bet on 100 octane showing up in 3 years and then not have it show up for 2 more and your company is out of business.
Nobody even really knew the difference in performance 100 octane would allow.
The 3rd option was one chosen by Halford at Napier with the Rapier and Dagger engines. Lots of little cylinders running at very high rpm. A few other designers may have followed that path but they had less success (sales) than he did.
A few engines split the difference, like the Merlin and Alison.
The internal combustion engine was only 30-40 years old and there wasn't a lot to go on. metal fatigue as metal fatigue dates pretty much from the 1930s, before that it was known as "crystallization" and while certainly known to exist it wasn't known how it happened or more importantly, how to stop it without just making parts bigger.
Many engineers/teams went with what they knew. P & W had built two Hornet 9 cylinder engines one of 1690 cu in and one of 1860 cu in. The larger one had cooling problems and P & W never again designed an engine using cylinders that large preferring to use more, smaller cylinders to get the same displacement even at the cost of adding a second row of cylinders to the engine. This despite P & W and Wright making vast improvements to cylinder finning on air-cooled engines over the next decade.

You also had different development policies in different companies. R-R and P & W being firm believers in the " flog it till it breaks, fix it, and flog it again" school.
In the back ground you also had advances in Metallurgy. You could no more have built a 1600 HP Allison in 1936 than you could have flown in space. At least one that would last for more than a few hours.

Getting back to the fuel, with say, 87 octane, fuel there was a definite limit to the BMEP one could get out of engine so for more power you could either use more inches or more rpm. More boost pressure was out until you got better fuel.
Some teams were "lucky" R-R for instance found when working on the Speed Spitfire that the Basic Merlin would stand-up to around 1800hp with breaking much of anything. How much of that "luck" was based on the old Buzzard engine and the racing "R" engines I don't know (hidden things like the radius of fillets where surfaces met). It gave R-R to confidence to keep going with the Merlin instead of sidelining it and working on replacements (Vulture and Griffon) which would have been necessary if 100 octane fuel had not come along when it did.
"Luck" was also on the side of R-R and the British in that their 100 octane fuel was actually about 20% better than US 100 octane fuel in 1939/40 and once they knew what to look for and specify it they went to about 30% better than 1940 US 100 octane. The octane scale is NOT liner and 100/130 is around 88% better than 87 octane fuel under rich conditions. This went a long, long way it the development of more power from the Merlin ( and many other engines). R-R and most of the Allied companies used the increase in allowable cylinder pressures to go for more peak power even at the cost of fuel economy.
The Germans (at least DB) seemed to pursue fuel economy with better fuels which cost them time in the development race.
Junkers is hard to trace as the 211 seemed to hit a wall before the 213 came out (211 designed for high rpm), too much time spent on the Jumo 222?

What nonsense.About the only truth in that is that Ford did indeed work to closer tolerances than RR as a mass production car manufacturer. The basic premise that the Merlin was not intended for mass production is not true.
Crewe was producing 303 engines per month and Glasgow had a planned output of 400 a month before the war even started. Glasgow quadrupled this to 400 per week by 1943.
The Ford/Manchester factory didn't produce an engine until mid 1941. I don't know where you are, but here the war started in 1939. In 1943 Ford was producing about 200 engines per week, half the rate of Glasgow.
The Merlin first entered production, as you well know, in 1936 and much had changed by 1939/40.

RR produced fewer Merlins in 1937 than planned but was still forced to cut production in 1938. Output was ordered cut again at the beginning of 1939!

As for being liquid cooled rather than a radial engine being its biggest failure, you are joking right? If you are not you really need to look at the engines that powered the most effective aircraft on both sides.
Funny that the Fw 190 developed from a radial engined fighter to one with an inline liquid cooled engine. The later versions were the best performers too. Maybe that was a failure of the Germans to understand the 'failings' of liquid cooled engines? They could have done with your expertise!
While you are putting the Germans right you can explain to all those Spitfire, Hurricane, Mustang, Mosquito, Lancaster, etc, etc pilots that their engines have a serious failing

Cheers

Steve

As Callum (among other people) noted, the German non-introduction of a 2-stage supercharged and/or turbo-charged engine until too late meant that they can't compete for no.1 spot in this competition. As they couldn't in real aerial warfare from mid-1943 on in ETO.
That is despite all of theorethical and experimantal work on their engines.

Indeed, as essentially the DB60x series used a single stage s/c with hydraulic coupling to drive impeller speed, neither the low nor hi alt s/c efficiency would ever be as good as a true two-stage system with mechanical gearing. As soon as multiple smaller impellers started to be used the efficiency went up. This resulted in less intake air heating (more hp!) as well as less parasitic power loss (more hp!) from the s/c at a given boost. It also allowed for greater absolute compression ratios as altitude went ever higher (more hp at 30k ft). Not to mention that there is always "some" loss of efficiency in such a fluid-coupled system.

Although the hydraulic clutching system was a lot better than gear driven single stage systems such as the early Merlins or many other engines. Still, if we are talking about "the best"... s/c or t/c performance is absolutely critical.

None of this is new info of course, but it is germane...

pbfoot said:

Pratt and Whitney r1800 and r2600 thats all that needs to be said

Click to expand...

Do you mean Pratt R1830 and R2800 or Wright R1820 and R2600?