Were German WWII engines "that bad"?

[Stephan Wilkinson]

Something I read on the always-amusing Internet claimed that one of the basic reasons the Germans put a lot of work into developing turbojet engines comparatively early (i.e. while the British were still claiming that if God intended airplanes to be powered by jets, he wouldn't have given us the propeller) was that German piston engines had reached the end of the line and no further piston-engine development was possible, if only because Germany lacked access to the necessary metallurgy.

Is this possibly true?

[shrike]

Something I read on the always-amusing Internet claimed that one of the basic reasons the Germans put a lot of work into developing turbojet engines comparatively early (i.e. while the British were still claiming that if God intended airplanes to be powered by jets, he wouldn't have given us the propeller) was that German piston engines had reached the end of the line and no further piston-engine development was possible, if only because Germany lacked access to the necessary metallurgy.

Is this possibly true?

I can't imagine that it would be, given that metallurgy, or rather the lack of important alloy ingredients, was what severely limited their jet engines. The same lack of high-temp alloys also stymied turbocharger development, with the Fw 190C being the only example I can think of. They were developing jet engines for the same reasons everyone else was - higher speeds. Remember, these are the same folks that set a world speed record that lasted from 1939 to 1969 (and might have been even higher minus political machinations)

German conventional engine development shows the same sort of increases in power over time as anyone else's, with one notable exception. The lack of tetra-ethyl lead meant that German fuel stocks were limited in ultimate octane, with 73 and 87 octane being the most common, versus US and UK fuels running to 100 or 115/145 by the end of the war. To counter this deficiency, the Germans used generally larger engines*, and operationally developed both water-methanol (MW50) injection and nitrous oxide injection (GM-1) to boost ultimate performance.

The power output of, say a JuMo213 optimized for high octane fuel at Reno would be awesome.

*
Merlin 1647cid 27l
Allison 1710cid 28l
DB601 2070cid 34l
DB603 2716cid 44.5l
DB605 2176cid 35.7l
JuMo213 2135cid 35l

[JohnB]

I've just read somewhere, that metallurgy was an issue for them, they lacked some metal or other (nickel?) required for high temps. But, I'd think if they couldn't for whatever reason produce good metal for piston engines, how could they do it for jets where the temps and are more critical?

[Stephan Wilkinson]

Thank you, guys, I didn't think bad pistons = good jets was the case.

[51fixer]

War one up-manship is one of the greatest development tools for all technologies.

As an example, That is why you have a 2200CID, 2000+HP Griffon in the Spitfire which started with a 900+HP Baby Merlin.

One other limiting factor in the German Aircraft Engines is that significant production came from Slave Labor and other unskilled but forced labor. The desire to produce great workmanship was a challenge under those circumstances. Even outright sabotage and work slow downs were factors, particularly towards the end.

The level of maintenance needed to keep the A/C flying had to be difficult as well as the Allied Air Superiority increased. When your quality of equipment is reduced you will spend more time to replace or repair parts. When your supply of parts is interrupted or non-exist-ant your operations are impacted and you have to operate at a handicap.

[shrike]

I've read similar to what shrike writes here as well. What he writes is a logical and researched understanding of the design of internal combustion engines during this era. Turbo engine design depended on high temp alloys the Germans lacked. Their turbojet engines, from my understanding, lasted less than 10 hours flying before needed replacing. Everyones internal combustion engine development for aircraft in this era reached the near maximum of the potential, limiting the ulitmate speed available using propellors. The Germans weren't alone in this. The jet engine was just the next way to fly faster.

The short TBO's were the result of compromises made to facilitate production, such as aluminized mild steel turbine blades (think automotive mufflers and exhaust pipes). The prototype JuMo 004's had a longer lifespan, but they also had free access to the exotic alloys denied to production.

Putting on the dreaded reenactor cap for a moment, I was scrubbing out an army coffee thermos (3 gallon, 1943) before an event a while back, when it struck me that while the Germans were desperately short of chrome, nickel and the like for jets, the US was using high grade stainless steel pots to keep coffee warm and tasting good. That, as much as anything, brings home the vast difference in the technological and production capabilities that ultimately decided the war.

[daviemax]

All these observations are interesting and generally correct. The fact is that German piston engines were not as prolific as those of the allies, particularly the U.S. Their reliance on Inverted-Vee designs brought with it dependency on coolant radiators and their associated weight and vulnerability. Radial engine development lagged, which certainly impacted their war effort. Having to rely on Gnome-Rhone radials is a testament to this lag, as is the lack of large 18-cylinder radials like the outstanding R-2800.

When the leader of Blohm und Voss saw the first captured R-2800 engine, he realized that the two halves of the crankcase were machined so precisely that they lapped such that no gasket was needed. He said then that he knew "that Germany had lost the war." While this is more a comment on manufacturing capability than design, nevertheless Germany simply got out-muscled in the aircraft engine department. Add to that the lack of strategic materials, lack of fuel, etc. and it is amazing they were as competitive as they were. Their jets were interesting and important historically, but they could not win the war.

[shrike]

All these observations are interesting and generally correct. The fact is that German piston engines were not as prolific as those of the allies, particularly the U.S. Their reliance on Inverted-Vee designs brought with it dependency on coolant radiators and their associated weight and vulnerability. Radial engine development lagged, which certainly impacted their war effort. Having to rely on Gnome-Rhone radials is a testament to this lag, as is the lack of large 18-cylinder radials like the outstanding R-2800.

The allies relied on liquid cooled engines as well for most of their land based fighters as well. On the allied side we have the Merlin, Allison and Griffon. To a lesser extent the big Napiers, although I would almost lump those in with the various duplex engines. On the German side DB 601, 603, 605, Jumo 211 and 213.
The Kraftei set up with the Jumos reduced complexity of liquid cooled engines to a very tidy QEC kit.

Radial engine development in the US was driven as much by the US Navy's desire not to have to carry glycol on carriers as anything else, although the reduced maintenance made them popular in the civilian world. The Gnome-Rhone engines were comparable to the 1820, in output and level of sophistication. As a huge plus they were in production and available (which BTW explains a lot about the B-17 and P-40 as well).
BWM's 801 series was no slouch in radial engines, but without a separate naval aviation branch to make it's wants known, you are right that the Germans spent less time on radials.

When the leader of Blohm und Voss saw the first captured R-2800 engine, he realized that the two halves of the crankcase were machined so precisely that they lapped such that no gasket was needed. He said then that he knew "that Germany had lost the war." While this is more a comment on manufacturing capability than design, nevertheless Germany simply got out-muscled in the aircraft engine department. Add to that the lack of strategic materials, lack of fuel, etc. and it is amazing they were as competitive as they were. Their jets were interesting and important historically, but they could not win the war.

Modern GA engines are built the same way. The 'gasket' is a silk thread stuck in goo*. And it was standard practice before the war, so why it should come as a surprise, I don't know.
Lack of fuel, and lack of pilots (prompted by a lack of fuel for training) were the undoing of the Luftwaffe.


*Guiderbrod 00 and Gasket-Maker #4 if you want to be precise

[Stephan Wilkinson]

When I built my Falco, I rebuilt the Lycoming with the silk thread between the case halves. But the only place I could find that sold actual silk thread was a bridal shop. I explained to them that I needed it to rebuild an airplane engine, which sort of baffled the nice ladies. But then one of them said, "Well, you're right, it IS very strong..." I think she thought I was going to wrap it round and round the block to hold it together.

To be fair to the Germans, when I recently rebuilt my Porsche 911 engine as a well-modified track engine, the case halves indeed went together without any gasketing, or any silk thread. Just an anaerobic sealant, which meant that once you dropped one case half onto the next with all the pistons in place through the holes, etc., you had 10 minutes to get a zillion stud nuts and washers in place and torqued down in the proper sequence. Took two of us, though I hate getting help.

[CoastieJohn]

Not sure if it was used for their engines but I know they wanted the cryolite mine in Greenland. The cryolite was used to process aluminum. I believe the Coast Guard and Army folks protected the mine during WWII.

http://commons.wikimedia.org/wiki/File: ... enland.jpg

[Invader26]

It's interesting to see how we pan the German technology. A friend of mine [still going at 94] was a fighter pilot flying everything from Gladiators/Hurricanes/Tomahawks/Kittyhawks/Spitfire IX/Tempest and Meteor told me the other day that the engines in those Meteors were not up to scratch either. They had were probably no more reliable than the 262 donks!

[Stephan Wilkinson]

Your incredible 94-year-old friend is the equivalent of the U.S. airline pilots--and there used to be a number of them--who had started out as DC-3 copilots and retired at 707 senior captains. I used to share a hangar with one who had actually hired on as a Ford Trimotor F/O.

[JohnB]

Your incredible 94-year-old friend is the equivalent of the U.S. airline pilots--and there used to be a number of them--who had started out as DC-3 copilots and retired at 707 senior captains. I used to share a hangar with one who had actually hired on as a Ford Trimotor F/O.

Coming back from the UK circa 1975, the captain of our Pan Am flight was an ancient who started out on the Boeing 314s and made it to the early days of jumbo jets. He pretty much summed up air transport history in his career.

[P51Mstg]

I heard another story about why Germans were going towards jets from piston engines.......

1. Jets ran on lower levels of fuel (Jet Fuel is as we all know not as refined as avgas) which were somewhat more available.

2. Obviously more performance.

3. MOSTLY, ease of production. I read that an DB engine for an ME 109 took over 2000 hours of machining time to make. A jet maybe 200 hours of machine time. While the DB had a "life" of say 300 or more hours and the jet MAYBE 25 hours, the aircraft they were installed in had a service combat life of possibly 10 hours. (You could expect it to be lost in that time). Hence they saved a lot of time with the jets.

Mark H

[jtramo]

I thinking it was material and not technology. The Germans technology was ahead of us in some ways. I have heard of the metallurgy issues and more importantly the octane/quality of the fuel itself. We had better gas. Less knocking=longer engine life. How much more time did we get out of our piston engines let alone early jet engines?

There was a reason for the push to defeat the Germans before the Japanese. A few more months/years of German development and we would have been dealing with some major technology leaps that we were very far behind.