Who would have had the technological edge in 1946?

[TheMarcksPlan]

What was the endurance of Allied jet engines in 1945?

Re bleed air into the turbine blades, that's still how jets work today. Pretty big achievement for 1945.

Allied engines varied greatly from about 10 to 15 hours to over 100 depending on the model. The Whittle design that became the RR Derwent was over 100 as were the production GE J31's. Early I-16's ran 10 to 15 as did the Allison J35 initially The Allison J33 (their version of the I-16) was equivalent to the J31. The Westinghouse J34 ran from about 25 to 30 and up to over 100 hours as production continued.

As for bleed air, that turbine blades, everybody figured that out. It wasn't unique to the Germans. Bleed air is also used for cooling the shell of the engine. That is now common. Using flame spray to help shield the blades was sort of unique to the Germans simply due to the lack of better choices and materials. Film cooling where the designer seeks to minimize heat transfer to the blade is not the most common method in use as this is more efficient than bleed air.

Like I said, it wasn't that the German engineers were stupid, they simply had limited materials to work with. Nobody makes turbine blades today by folding sheet metal and spot welding it. In many cases, turbine blades in jet engines and car turbochargers are now going to ceramics instead.

Can you start providing sources, please?

Buy a copy of the book I'm doing on advanced WW 2 technology when it comes out. I know, that's a bit of a cop out, but it's a long list from many different sources. I will say that both Rover and Westinghouse screwed the pooch when it came to jet engines. Both were total mess ups in a way no German firms were. Rover dithered and dithered with minor design changes on the original Whittle engine to the point even the British bureaucrats in the Air Ministry finally took the program away and gave it to Rolls Royce.
In Westinghouse's case, internal idiocy, management failure, and engineering incompetence took away what would have been a promising new field for the company and handed it to GE and Allison.

Ok that'll have to do for now I guess.

In order to buy the book, however, I'm going to need an assurance that you no longer believe that wing loading and maneuverability are unrelated.

[Aber]

Can you start providing sources, please?

How about Aviation Week on-line archive?

https://archive.aviationweek.com/issues/1945

I believe there's an article about post-war tests of British jet engines in the German high speed wind tunnel with run times > 50 hours.

[T. A. Gardner]

Ok that'll have to do for now I guess.

In order to buy the book, however, I'm going to need an assurance that you no longer believe that wing loading and maneuverability are unrelated.

Fair enough. And yes, wing loading has something to do with maneuverability but it isn't the only factor involved, and I never believed differently on that.

[At ease]

Then when you throw in the roughly 10 hours or less between engine changes, this made German jets a self-defeating proposition.

This wasn't a tech issue though; the Germans simply lacked access to a few critical elements required for long endurance of high-temp jet components (most especially cobalt). The original Jumo designs used cobalt and had much longer endurance; the production designs were adaptations to the strategic material situation.

Even today it is simply impossible to build a durable jet engine without certain alloys (or, more recently, ceramics - but that's decades ahead on the tech path).

In part it was. The Zweibel that was used in the exhaust to vary the outlet size was a design flaw. There were flaws in the turbine and compressor blade design as well. These were things that were problems mainly because of lack of experience with jet engine design compounded by Germany having limited access and knowledge on turbine blade profiles. Germany turned to Brown-Boveri in Switzerland for help on these, but that company's experience with gas turbines versus steam turbines was limited.
Companies like Vickers, GE, or Westinghouse had far more in-house design experience with turbines than Junkers or BMW with GE having considerable gas turbine design experience from building turbochargers so they had an advantage in designing jet engines.

Yes, the lack of high temperature alloys the Allies had access to didn't help things one iota.

As a direct example of this, Junkers made their turbine blades hollow out of sheet metal and flame sprayed them with alumina. They forced bleed air through the blades to cool them. It was a rather ingenious solution but led to serious problems dynamically balancing the turbine wheel which led to early bearing failures. The problem was trying to make each blade of equal weight and profile when you are folding sheet metal and spot welding it. The Junkers engineers weren't stupid, they just had limited ways to solve problems and were under pressure to put out a product NOW versus the Allies who had more resources and weren't being pressed with imminent defeat.

What was the endurance of Allied jet engines in 1945?

Re bleed air into the turbine blades, that's still how jets work today. Pretty big achievement for 1945.

According to "Greg's Airplanes and Automobiles @10.45 in the following video, the Zweibel was NOT a design flaw.

He states that "it is an advanced feature".

The never ending criticism of German jet engine life in particular by T. A. Gardner in various forums - in particular at ArmchairGeneral for example, that 10-15 hours being totally inadequate should be viewed in light of information also provided by "Greg's Airplanes and Automobiles" stating that in 1947 the TBO(time between overhaul) of the first major US axial jet engine, the General Electric J47, was only 15 hours(rising quickly with time to thousands of hours with further development time and not being under pressure to minimise usage of rare strategic materials).

For confirmation of his statement about this see @20.50 of:

World War Two JET POWER

by:

Greg's Airplanes and Automobiles

https://www.youtube.com/watch?v=4N5lNOYlOb8

".....but initially it was 15 hours....."

For further comments about TBO of the early iterations of the G. E. J47 axial flow engine see:

https://en.wikipedia.org/wiki/General_Electric_J47

Note the use of sources such as "Flight Magazine[Flight Global]" in the above "Wiki" entry.

P.S. It is interesting to note that not all commentators on this subject from the USA have such "slanted" views on the subject as TAG does everywhere he goes.

Have a listen to what the producer of the above video says right at the end of it@ 23.35.

[T. A. Gardner]

According to "Greg's Airplanes and Automobiles @10.45 in the following video, the Zweibel was NOT a design flaw.

He states that "it is an advanced feature".

The never ending criticism of German jet engine life in particular by T. A. Gardner in various forums - in particular at ArmchairGeneral for example, that 10-15 hours being totally inadequate should be viewed in light of information also provided by "Greg's Airplanes and Automobiles" stating that in 1947 the TBO(time between overhaul) of the first major US axial jet engine, the General Electric J47, was only 15 hours(rising quickly with time to thousands of hours with further development time and not being under pressure to minimise usage of rare strategic materials).

For confirmation of his statement about this see @20.50 of:

World War Two JET POWER

by:

Greg's Airplanes and Automobiles

https://www.youtube.com/watch?v=4N5lNOYlOb8

".....but initially it was 15 hours....."

For further comments about TBO of the early iterations of the G. E. J47 axial flow engine see:

https://en.wikipedia.org/wiki/General_Electric_J47

Note the use of sources such as "Flight Magazine[Flight Global]" in the above "Wiki" entry.

P.S. It is interesting to note that not all commentators on this subject from the USA have such "slanted" views on the subject as TAG does everywhere he goes.

Have a listen to what the producer of the above video says right at the end of it@ 23.35.

This is what's called a trivial objections fallacy. My point wasn't about some particular niggling detail on engine design, but rather pointing to the fact that Germany did not have some massive lead in technology over what the Allies possessed.

The usual version presented was that the Germans held some major lead in many technologies in 1945 over their opponents. This is clearly and demonstrably false. While the Germans certainly had advanced technology, so did their opponents, and often that of their opponents was as good or better than what the Germans possessed. Of course, there were differences in some areas simply because of choices different nations made based on their perceived and actual needs versus what those were for Germany.

What the above post argues is that trivial points about jet engine design--even those I mentioned as but examples of the larger picture--are to miss the point of the argument. It isn't whether the Zweibel design was better or worse on its own, but rather that the Allies possessed jet engine technologies on par, at a minimum, with Germany in 1945 and in some ways were in advance of the Germans. In fact, I might point out that the above response is to some degree a slanted one in favor of the Germans--something that frequently is made by a good many people talking about WW 2 technology.

[At ease]

You are the one continually criticising design elements such as the Zweibel.

If it really is trivial, you have done a great job of elevating it to something more than trivial.

You are also incessantly pointing out the low TBO of the German engines.

I'll bet you chocked on your cornflakes when Greg demonstrated a TBO of 15 hours for the J47 even by 1948, having 3 years of developmental knowledge available since VE day, and unfettered access to precious metals.

(I have seen reference to this TBO in an article about the North American B45 Tornado which used the J47, but cannot put my hands on the exact source ATM)

Also, please point to an American or UK aircraft that was capable of routine level speeds of 540(statute) mph in mid 1944.

You can't, of course.

Even with "overboosting", or having a 5 minute WEP(war emergency power) limit, 500mph was only reachable with EXTREME difficulty by only one contemporary Allied design, namely the Republic Thunderbolt XP-72.

Routine Allied production aircraft carrying a representative war load(i.e. at operational weight) were quite well below the mark that was routinely achievable by the Me262.


P.S. Another "cornflakes" moment is the comment that I highlighted in the video @ 23.35.

P.P.S. Here is a "teaser" about the N.A. B45 and engine reliability:

Soon after its entry to service on 22 April 1948, B-45 operations were troubled by technical problems, in particular poor engine reliability.

The first production B-45 flew in February 1948, and the Air Force took delivery of 22 B-45s in April 1948. Powered by J35 turbojets and not considered combat-ready, they were assigned to training duties and to conduct various test programs. The next batch were powered by the more powerful J47 turbojets. The first B-45As entered service in November 1948 with the 47th Bombardment Group, and the initial order of 96 was completed in March 1950.

The first B-45As were not equipped with bomb fire control systems or bombsights. They suffered from gyrocompass failures at high speeds, unhooked bomb shackles, engine fires, and inaccurate cockpit gauges. The AN/APQ-24 bombing and navigation radar on some B-45s was maintenance heavy, and malfunctions in the pressurization limited the altitude at which the aircraft could operate.

https://en.wikipedia.org/wiki/North_Ame ... 45_Tornado

No guarantees, but I will keep looking for the more detailed source that I am certain that I have read in earlier years.

[Aber]

You are also incessantly pointing out the low TBO of the German engines.

I'll bet you chocked on your cornflakes when Greg demonstrated a TBO of 15 hours for the J47 even by 1948, having 3 years of developmental knowledge available since VE day, and unfettered access to precious metals.

See post #32 for British jet engine life in 1945

[At ease]

But British, and American, jet engines were not providing the performance level that the German jets were producing by VE day.

The Meteor, for example, was significantly slower than the time equivalent Me262.

So was the Lockheed P80.

Closely study, like I have over the years:

http://www.wwiiaircraftperformance.org/ ... eteor.html

My point about TAG's posts are that he forever harps about German jet engine life, but as I pointed out the GE J47 was NO BETTER than the German 1945 effort even BY 1947/48.

If ACG was still alive [ thanks for nothing CARPE DIEM IDIOT ] I would have been able to reference many of the posts referencing this multi year "discussion" with all of the sources I had made reference to over the years.

Anyway, don't just take my word for it.

Read the books by the world's most experienced test pilot, Capt. Eric "Winkle" Brown(rip).

Watch his youtube videos.

See what he has to say about the subject.

I linked to his material many times at ACG, causing many USA/UK posters to have "cornflakes" moments.

This is one video I have referred to at ACG:

https://www.youtube.com/watch?v=zhVp0dvwr68

See @ 3 min.30 in particular

[T. A. Gardner]

And, At Ease misses the point of this whole exercise. The Allies had jet engines and jets. In 1944 - 45 they really didn't need them to win. The Germans, in their position needed a paradigm shift in something to win. It had to be something that would render the numerical superiority and qualitative parity of the Allies irrelevant.
Germany thought jets might do that. The problem was their jets had such poor reliability and used so much fuel, that keeping more than a mere handful flying daily was impossible for them. Any advantage that some particular German jet might have had was transitory at best. The Allies could easily catch up with such a development as they had the same technology available but were largely unwilling to field it because of poor reliability choosing instead to continue its development to make it worth deploying.

For the Germans, they needed a jet engine that was reliable, and one that wasn't a gas guzzler. That wasn't happening. The Allies were deploying aircraft with variations of the Whittle engine that had somewhere between 5 and 10 times greater life expectancy than a Jumo 004. That was slowly happening. The J47 had poor reliability, but its German equivalent was the HeS 011, not the Jumo 004 and the 011 was barely bench running by the time the war ended.

Postwar, the winners could take more time in developing new technologies, and if some of these were deployed to service in a peacetime setting, the lower pace of operations made it possible to improve them at a pace that matched their use.

[At ease]

And, At Ease misses the point of this whole exercise. The Allies had jet engines and jets. In 1944 - 45 they really didn't need them to win. The Germans, in their position needed a paradigm shift in something to win. It had to be something that would render the numerical superiority and qualitative parity of the Allies irrelevant.
Germany thought jets might do that. The problem was their jets had such poor reliability and used so much fuel, that keeping more than a mere handful flying daily was impossible for them. Any advantage that some particular German jet might have had was transitory at best. The Allies could easily catch up with such a development as they had the same technology available but were largely unwilling to field it because of poor reliability choosing instead to continue its development to make it worth deploying.

For the Germans, they needed a jet engine that was reliable, and one that wasn't a gas guzzler. That wasn't happening. The Allies were deploying aircraft with variations of the Whittle engine that had somewhere between 5 and 10 times greater life expectancy than a Jumo 004. That was slowly happening. The J47 had poor reliability, but its German equivalent was the HeS 011, not the Jumo 004 and the 011 was barely bench running by the time the war ended.

Postwar, the winners could take more time in developing new technologies, and if some of these were deployed to service in a peacetime setting, the lower pace of operations made it possible to improve them at a pace that matched their use.

Lies.

The Allies were desperate to get jets into service, especially as the US daylight bombers crews were fearful of potential losses.

The Coming of the German Jets
By Donald R. Baucom USAF
Aug. 1, 1987

[.....]

Jets in the Air

Allied air force leaders were not surprised in July 1944 when their airmen first encountered German jet fighters in air combat. The Ger­mans had been flying jet aircraft for almost five years, the British for about three years, and the Ameri­cans for more than a year and a half.

Readers of AIR FORCE Magazine may recall from Lee Payne’s article (“The Great Jet Engine Race And How We Lost,” January ’82 is­sue) that the British and Germans developed turbojet engines inde­pendently of each other. Although the British were the first to begin work on a jet engine, it was the Ger­mans who flew the world’s first jet aircraft, a Heinkel He-178, on Au­ gust 27, 1939. In fact, the Germans flew a second jet aircraft, the Heinkel He-280, before a British jet, the Gloster E28/39, made its maiden flight in the spring of 1941.

One of the early flights of the Gloster jet was observed by Maj. Gen. H. H. “Hap” Arnold, Chief of the AAE When he returned to the United States, he immediately set the AAF to work developing its own jet.
[.....]

Responding to the Crisis

To deal with the possibility that Doolittle’s appraisal might be cor­rect, General Spaatz sought and se­cured Gen. Dwight D. Eisenhower’s approval for a two-pronged strat­egy. First, Spaatz enlisted the sup­port of his superiors to accelerate America’s jet program. P-80 produc­tion was given the same top priority accorded the B-29.

Spaatz also sought a higher bombing priority for jet targets, the goal being to place 10,000 tons of bombs on such German assets as jet factories and jet training facilities. This, AAF planners estimated, might set back enemy jet produc­tion about three months. Spaatz’s strategy was to get an American jet into operation about the time the German jet threat matured in the summer of 1945. The AAF would accelerate its jet production pro­gram while retarding that of the Ger­mans by three months. This should give the US a chance to catch up.
[.....]

Other Responses
[.....]

In addition to conducting special operational tests, pushing the devel­opment of the P-80, and bombing German jet-related targets, AAF leaders settled on several other measures for dealing with the Ger­man jets. At least some of these de­rived from the jet-conventional fighter trials of the summer of 1944.

For one thing, American airmen decided to push their long suit—numbers. They would make minor modifications to existing aircraft, but would do nothing to disrupt pro­duction rates. Thus, Doolittle wrote to Arnold in August 1944: “Devel­opment of new equipment is ex­tremely important, but should not interfere unduly with the produc­tion and improvement of existent equipment as we hope that we can win this war with continually im­proved conventional aircraft.”

Similar sentiments were ex­pressed by General Spaatz in March 1945. If the jets were used against American bombers before an Amer­ican jet was available, he wrote to Gen. Barney Giles, “the German technical advantage must be coun­tered by overwhelming numbers of conventional fighters manned by pi­lots trained to both outthink and outshoot the German.”

One AAF tactic called for the use of a substantial number of conven­tional fighters, perhaps as many as ten for every jet engaged, to box in attacking jets so that they could not escape without passing through the sights of an AAF fighter or two. This method aimed to neutralize the jet’s advantage in speed, which nor­mally allowed the Me-262 to disen­gage from combat if its pilot found himself at a disadvantage.

[.....]

Lt. Col. Donald R. Baucom received his B.S. degree from the Air Force Academy in 1962 and his Ph.D. in the History of Science from the University of Oklahoma in 1976. His primary career field in the Air Force has been communications-electronics. He has served as an associate professor in the Air Force Academy History Department and as a member of the Air War College faculty. Other important assignments have been Director of Research, Airpower Research Institute, and Editor of the Air University Review. He is currently in the Office of Air Force History in Washington, D. C., where he is at work on a history of the Air Force and its response to research and development from 1941 through 1961. This article is a version of a paper presented to a seminar at the Air and Space Museum in November 1986.



https://www.airforcemag.com/article/0887german/

[T. A. Gardner]

Thus, Doolittle wrote to Arnold in August 1944: “Devel­opment of new equipment is ex­tremely important, but should not interfere unduly with the produc­tion and improvement of existent equipment as we hope that we can win this war with continually im­proved conventional aircraft.”

Similar sentiments were ex­pressed by General Spaatz in March 1945. If the jets were used against American bombers before an Amer­ican jet was available, he wrote to Gen. Barney Giles, “the German technical advantage must be coun­tered by overwhelming numbers of conventional fighters manned by pi­lots trained to both outthink and outshoot the German.”

That doesn't sound like "desperation." That sounds like pragmatism. It also doesn't change the reality that Germany couldn't have kept more than maybe 50 or so Me 262 flying on any given day, probably less.

[At ease]

Thus, Doolittle wrote to Arnold in August 1944: “Devel­opment of new equipment is ex­tremely important, but should not interfere unduly with the produc­tion and improvement of existent equipment as we hope that we can win this war with continually im­proved conventional aircraft.”

Similar sentiments were ex­pressed by General Spaatz in March 1945. If the jets were used against American bombers before an Amer­ican jet was available, he wrote to Gen. Barney Giles, “the German technical advantage must be coun­tered by overwhelming numbers of conventional fighters manned by pi­lots trained to both outthink and outshoot the German.”

That doesn't sound like "desperation." That sounds like pragmatism. It also doesn't change the reality that Germany couldn't have kept more than maybe 50 or so Me 262 flying on any given day, probably less.

This does:

(from the article quoted from above by Baucom)

Responding to the Crisis

To deal with the possibility that Doolittle’s appraisal might be cor­rect, General Spaatz sought and se­cured Gen. Dwight D. Eisenhower’s approval for a two-pronged strat­egy. First, Spaatz enlisted the sup­port of his superiors to accelerate America’s jet program. P-80 produc­tion was given the same top priority accorded the B-29.

Spaatz also sought a higher bombing priority for jet targets, the goal being to place 10,000 tons of bombs on such German assets as jet factories and jet training facilities. This, AAF planners estimated, might set back enemy jet produc­tion about three months. Spaatz’s strategy was to get an American jet into operation about the time the German jet threat matured in the summer of 1945. The AAF would accelerate its jet production pro­gram while retarding that of the Ger­mans by three months. This should give the US a chance to catch up.

[Michael Kenny]

Similar sentiments were ex­pressed by General Spaatz in March 1945. ...................

March 1945, The Russians are on the Oder and the Western Allies the Rhine. Food shortages have become so serious in Germany a 30-50% reduction in the already meagre bread & fat allocation being planned, 25% of the pre-war stock of houses have been totally destroyed, capitulation (from March 1st) is a mere 9 weeks in the future and it is believed a single class of aircraft will have such a significant impact that it can instantly halt and then reverse/negate all the Allied advantages?

Spaatz’s strategy was to get an American jet into operation about the time the German jet threat matured in the summer of 1945.

By then the Allied strategy of not rushing an untested technology in the front line and relying instead on their proven designs was vindicated-Germany went kaput before the summer.
In Britain in 1944 they were so sure the war was won they cancelled most of the development work on weapons not expected to be ready by the summer of 1945 and planning priorities were shifted to prioritise post-war rebuilding & reconstruction.

I recommend a reading of the 1945 Goebbels Diaries where the despair at not being able to defend against the bombing raids is mixed with this same type of totally unjustified belief that 'secret weapons' were on the point of reversing German fortunes.

[Peter89]

The interesting nature of Luftwaffe development was that they had many inconsistent projects going on with wide and wild aims. But they had little to do with operational functionability. It was also very interesting how little effort they've put in working designs like He 100 or Ju 90 compared to inherently dysfunctioning designs like the He 177. There was little, if any coordination between the ground echelons and the design. So let's say by some miracle the Germans would be able to produce 10,000 operational Me 262. Okay, but where they will take off? The normal airfields were incapable of serving them properly. Also how they will be serviced and maintained? You can't deploy a Ju 88 Werk and expect them to do a proper job on Me 262. Also the engines - how they are going to be replaced at every 12 operational hours? Some would even say that these late war fighters were kamikaze bombs with extra steps.

[danebrog]

As always, the human factor is completely neglected here: not "everyone" can fly the machine, it needs very qualified personnel to realise its potential.
This was already lacking in the Bf 109 and Fw 190 pilots in late 1943, because pilot training was an unloved and neglected stepchild in the Luftwaffe. (Even when there was still enough fuel).

Even an "F-86" or "MiG-15" with a swastika would not have made a difference when accident-free take-offs and landings were already a challenge.
In this respect, the question of technological edge is irrelevant for the course of the war if there is a lack of sufficient specialists who can also turn this edge into successes.