Zyzygie’s Mumbles and Rambles

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This is just wishful thinking GrauGeist. The key was always the specific alloy Nimonic. The major engine manufacturers - British, American, French, German and Russian - all exclusively used Nimonic hot end components after the War, at least until the 80s. And it's still used extensively.

The alloy had to not only resist corrosion, high stress, but more importantly creep. At such combinations of high stress and high temperature, most materials will slowly elongate. This is obviously a problem for a turbine blade which has to run with minimal end clearance.

See:
https://www.magellanmetals.com/nimonic-75

"...Nimonic alloys are made up of nickel and chromium. These alloys are characterised by their high-temperature low-creep and high performance. Additives like titanium and aluminium are used for enhancing the strength of the alloy..."

"...Nimonic 75 is an 80/20 nickel-chromium alloy containing titanium and carbon as additives. Nimonic 75 was first introduced for use as turbine blades during the 1940s. Nimonic 75 is readily fabricated and welded. Nimonic 75 alloy exhibits good corrosion resistance, mechanical properties and heat resistance..."
 
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The He S 8 was planned to spin at 13,500 rpm. No German alloy could have withstood the combination of stress and temperatures at that speed, even with air cooling. (Which by the way had the downside of sapping a lot of power from the engine.)

Just read my previous posts in this regard...

He S 8 Performance

Wikipedia

The Derwent 1 thrust to weight ratio was 2.04. The Derwent 5 was 3.2.
 
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"...one thing that had puzzled me was the frequent claim that nickel shortages had "caused" the development of the hollow turbine blades. Several scholars in the field of technology & innovation studies (e.g. Gibbert & Scranton 2009) have claimed that Ni shortage "induced" this "radical innovation" that put the German jet engine designers several years ahead of the Allies and caused them to "invent" a technology that is in use even now."

"However, this version of the events seems a bit problematic when one considers the actual nickel usage and Germany's nickel situation. According to figures for Ni usage per engine in Kay's "German Jet Engine and Gas Turbine Development 1930-1945" (2002), the entire production run of Jumo 004 engines, for example (some 6010 engines) used approximately 40 metric tons of nickel. This is not an insignificant amount, but compared to 1944 Ni supplies (10900 tons), consumption (9500 tons), or stocks (7900 tons) (U.S. Strategic Bombing Survey), the needs amount to little more than rounding error..."

"...Even if the wildly optimistic turbojet production plans, calling for ca. 39 000 BMW 003 and 44 000 Jumo 004 engines to be built by January 1946 had materialized, the nickel use would have been only some 250 tons. And even if the hollow blade designs - which, at best, saved some two thirds of nickel per engine compared to solid Tinidur blades - had not succeeded, the nickel consumption would have been only about 820 tons..."

Early German gas turbine development
 
As I recently poated in another thread, the thrust to weight ratio of an engine is certainly a key factor, but most overlook the weight of the aircraft they are being installed in and most importantly, the weight of the engines themselves.

The HeS8 weighed roughly 840 pounds and the Jumo004 weighed aboit 1,585 pounds - nearly twice the weight for less thrust.
 

I don't follow. The He S 8 had a thrust of 1300 lb, as against 1980 for the JUMO 004..?
 
An excerpt from Flight International of October 1947 on the importance of Nimonic.

Without this alloy, the gas turbine was arguably just a "pie in the sky" concept. If Germany had stocks of 7,900 tonnes of nickel in 1944, it should have been prioritised for jet engines. Tanks and submarines should have been absolutely secondary. The Russians managed with about one third of the percentage of nickel in their tank armour compared to the Germans, but made up for it by strategically sloping the armour to make it more effective:







Stalin's Revenge: Operation Bagration and the Annihilation of Army Group Centre

Stalin's Revenge

 
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Although the Germans had some technical successes such as swept back wings, overall they were arguably quite thick.

Their investment of resources in the V1 and V2 weapons was a total waste. Each V2 carried only a one tonne warhead, and they only fired about four thousand during the War. That's about equivalent to what the Allies would deliver in the bombing in one day. The story with the V1 is similar.

The cost of the V-weapon program was roughly equal to that of the Manhattan project. Now that DID have a high cost-effectiveness ratio. The Germans were complete non-starters in this technology.

They also lagged badly in terms of radar.

The failure in terms of the development of jet engine materials is absolutely extraordinary...

 
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A couple of thousand RELIABLE Me 262s would have completely stopped the Allied daylight bombing campaign in its tracks.

But OK, not the atomic bombs.
 
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If the Germans had built a couple of thousand GOOD Me 262s, all of the above problems would have been fixed, and more, except for the first, which wasn't a problem...
 
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Zyzygie said:
If the Germans had built a couple of thousand GOOD Me 262s, all of the above problems would have been fixed,
Click to expand...

One thing the Germans' Gotterdammerung scenario never takes into account was the fact that the Allies first became aware of the Me 262 through reconnaissance photos over a year before it entered service. When the first images of it were taken, Whittle was brought in to examine the pictures and the intelligence branches produced estimates about its performance. A crashed example recovered in France in mid 1944 was examined and from that the boffins were able to give their thoguhts on its capabilities and they were pretty close to the mark, which worried the Brits. The Me 163 was already identified as a rocket fighter and had been first photographed in 1942. A paper was produced that predicted that by the end of 1944, the Germans could have around 1,000 jet powered aircraft in service, which worried the Allies considerably. This had the result of increasing bombing campaigns against sites that were contributing to the aviation industry and increasing the pace of development of Alllied jets.

Photo reconnaissance would have seen this production, had it taken place and actuated a plan to defeat it, had it transpired. The Allied intelligence services had a good handle on the state of Germany's secret projects, certainly better than what the Germans understood they knew. By mid to late 1944, when it was realised that the number of jets the Germans could produce in service was far lower than predicted, there was a collective sigh of relief among the British Air Staff, although the Americans were not so relieved, as it was their bombers taking the hits from jets being used as bomber interceptors.
 
For interest: the Axis and strategic nickel supply. Obviously important for the Me 262 engine development, as well as tank armour and subs:

The Coinage they are talking about was about 2200 tonnes. Pretty handy, but small relative to Germany's 1944
stockpile.
 
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I couldn't have put it better myself:

 

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You yourself have cited references indicating that German metallurgists understood the effect of nickel in limiting creep and the development of a 60% nickel version of Krupp Tinidur alloy (standard was 30%) was rejected on the bases of anticipated material shortages leaving Junkers with Tinidur 30%.

Nevertheless the Heinkel HeS 30 (also known as 109-106 and HeS 006) Heinkel HeS 30 - Wikipedia achieved a thrusts to weight ratio of 2.2:1 (860KP/390KG) and a frontal area that were not bettered till 1947. Certainly as good as any allied centrifugal engine. It used an axial compressor but it was of the reaction type, not the impulse type which is both more efficient and lighter.

The issue that severely limited the first generation of allied aircraft was not thrust to weight ratio but the frontal area and the problems it created for airframe integraion. Solved neatly by the XP-80 solved in the Meteor with huge nacelles and jet pipe extensions.

German industry was rigorously assessed for usage of labour and critical materials and sometimes it seemed to produce poor decisions and trade offs in quality. For instance the combustion chamber cans and exhaust nozzles of the Jumo 004 were of mild steal and caused many problems and limited maintenance life, it didn't even need much nickel just a corrosion resitant chromium. A tradeof in combustion chamber and tail pipe alloy caused great reductions in life, quite a few failures and frequent maintenance.

The BMW 003 had the more sophisticated accelerator valve fuel control system that measured air mass flow not just engine RPM that the Jumo 004 may or may not have ever received till April 1945. One reason the 003 was delayed was due to the order to switch from standard aviation fuel to a diesel like fuel chosen by junkers. This disrupted BMW designs.

I thought US engines used Inconel, hasteoly or alloys derived from turbocharger practice?
 
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