Zyzygie’s Mumbles and Rambles

[Zyzygie]

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?

I don't know where I indicated that the German engineers had knowledge of Nimonic or its equivalent. If they did, it would have been a trivial exercise for them in the Soviet Union after the War (where they also had access to lots of nickel and chromium), to build a good JUMO 004 and put it in an Me 262. They went instead for stealing the Nimonic and copying the RR Nene with centrifugal compressor ...?

If you check the RAE figures, drag attributed to the engines is lower for the Meteor than the Me 262. Maybe due to wing/engine interference effects with the Me 262?

Koopernic, you haven't addressed the question of why Germany didn't use their Nimonic knowledge when they had plenty of nickel and chrome in strategic stocks?

 

[Zyzygie]

I've found a source relating to material selection. Maybe this is what you are referring to?

 

[GrauGeist]

The Meteor had less drag because each engine nacelle was embedded in the wing, where the Me262, He280, Ar234 and Hs132 all had an external nacelle either undersling beneath the wing or above the fuselage - it was the He178 that had the most efficient arrangement with the engine embedded in the fuselage with the intake at the nose.

 

[Zyzygie]

I've found a source relating to material selection. Maybe this is what you are referring to?

View attachment 572171
View attachment 572172

View attachment 572173
View attachment 572174

With 8900 tonnes of nickel and 33000 tonnes of chromium, there was no shortage:

 

[GrauGeist]

There was a shortage because the strategic materials needed for jet engines was prioritized for Tank production, gun/cannon production, U-Boat production, engine (piston) production and even stahlhelm (helmet) production, etc.

The jet engine program never reached a high priority, regardless of what some publications may claim.

 

[Zyzygie]

There was a shortage because the strategic materials needed for jet engines was prioritized for Tank production, gun/cannon production, U-Boat production, engine (piston) production and even stahlhelm (helmet) production, etc.

The jet engine program never reached a high priority, regardless of what some publications may claim.

That was a BIG mistake. To build a U-Boat, you've got to stop the bombers. Even the submarine pens at Brest with 7-metre reinforced concrete roofs were not enough protection from the supersonic 10 tonne Grand Slam bombs.

 

[GrauGeist]

But the U-Boats were highly effective in refusing Britain the desperately needed supplies.

Since the Kreigsmarine (surface elements) and Luftwaffe was ineffective in challenging the RN and Allied surface fleets, the U-Boat force was a much needed tool.

 

[Zyzygie]

But the U-Boats were highly effective in refusing Britain the desperately needed supplies.

Since the Kreigsmarine (surface elements) and Luftwaffe was ineffective in challenging the RN and Allied surface fleets, the U-Boat force was a much needed tool.

The Battle of the Atlantic was well and truly over by 1944. The horse had well and truly bolted.

The Me 262 should have been the top priority.

 

[Koopernic]

I don't know where I indicated that the German engineers had knowledge of Nimonic or its equivalent. If they did, it would have been a trivial exercise for them in the Soviet Union after the War (where they also had access to lots of nickel and chromium), to build a good JUMO 004 and put it in an Me 262. They went instead for stealing the Nimonic and copying the RR Nene with centrifugal compressor ...?

If you check the RAE figures, drag attributed to the engines is lower for the Meteor than the Me 262. Maybe due to wing/engine interference effects with the Me 262?

View attachment 572170

Koopernic, you haven't addressed the question of why Germany didn't use their Nimonic knowledge when they had plenty of nickel and chrome in strategic stocks?

Two things to note about that RAE test.
First is that the Meteor III had 3 or 4 difference nacelles. Welland nacelles, extended Welland nacelles, Derwent Nacelles and extra extended Derwent nacelles. Which ones are the report about? Same with the Meteor I which had many nacelle changes. These were caused by the 'fatness of the centrifugal engines'
Second is look at the speed the test was conducted at, which is 100ft/sec (i.e. 30m/s or 108km/h or 65mph). (corrected) This is not going to tell us much about shock drag at above Mach 0.6. The Me 262 was operating at Mach 0.80. The Germans were operating several supersonic wind tunnels, the British had non of any size.

Drag of a swept wing is reduced to 1/cosine(sweep angle) which works out at about 5-6% less drag on the Me 262 but there are likely other effects such as the finer nacelles on the Jumo 004 whose skin usually had terrible construction quality. That explains some of the British test results, their tolerances were better at this stage of the war.

Regarding the failure to use sufficient refractory alloys in the Me 262. I think they simply over rationed r misjudged the importance of the supply of raw materials to the Jumo 004. As I pointed out despite already using only about 12kg on the Jumo 004B1 they went to the effort of reducing this to 6kg on the Jumo 004B4 through use of hollow turbine blades. Just using stainless steel for the combustion chamber cans. The 1900kg thrust BMW P3308, according to Kay, had a variant with a pure steal turbine of only 2 hours life, essentially a single use system. That gives an idea of the sense of urgency in reduction of chromium and nickel. And of course in 1944 the stockpiles were getting lower.

 

[Zyzygie]

Regarding the failure to use sufficient refractory alloys in the Me 262. I think they simply over rationed r misjudged the importance of the supply of raw materials to the Jumo 004. As I pointed out despite already using only about 12kg on the Jumo 004B1 they went to the effort of reducing this to 6kg on the Jumo 004B4 through use of hollow turbine blades. Just using stainless steel for the combustion chamber cans. The 1900kg thrust BMW P3308, according to Kay, had a variant with a pure steal turbine of only 2 hours life, essentially a single use system. That gives an idea of the sense of urgency in reduction of chromium and aluminium. And of course in 1944 the stockpiles were getting lower.

I have to shake my head... this is exactly the way to lose a War. Big Time.

Hauling up a white flag when you still have stocks of well over a year's supply...

26 months' supply for nickel and 10 months' for chromium in place in 1944. Much less chromium was required than nickel for the JUMO. The Me 262 Assessment was right about German governmental incompetence.

 

[Zyzygie]

"Second is look at the speed the test was conducted at, which is 100ft/sec (ie 30m/s or 50km/h or 30mph). This is not going to tell us much about shock drag at above Mach 0.6. The Me 262 was operating at Mach 0.80."

Have you looked at the Cd charts I posted?
See post 808.

Do you accept that the Me 262 was not a dogfighter?

Do you deny the gross incompetence of the German government in hoarding strategic metals needed for the jet fighters which were the only defence against the bombers destroying Germany?

1400 Me 262s we're built and only about 20-40 could get into the air on a given day. Adolf Galland said that if he had had a couple of hundred he could have stopped the bombing.

 

[Zyzygie]

The Miles M 52 undergoing supersonic testing in RAE wind tunnel in 1946:

Royal Aircraft Establishment - Wikipedia

That Mach 1.3 aircraft was canceled after the War due to shortage of funding and the fact that it was just a research project.

A scale model was tested at Mach 1.38.

 

[Koopernic]

"Second is look at the speed the test was conducted at, which is 100ft/sec (ie 30m/s or 50km/h or 30mph). This is not going to tell us much about shock drag at above Mach 0.6. The Me 262 was operating at Mach 0.80."

Have you looked at the Cd charts I posted?
See post 808.

Do you accept that the Me 262 was not a dogfighter?

Do you deny the gross incompetence of the German government in hoarding strategic metals needed for the jet fighters which were the only defence against the bombers destroying Germany?

1400 Me 262s we're built and only about 20-40 could get into the air on a given day. Adolf Galland said that if he had had a couple of hundred he could have stopped the bombing.

Whats a good dog fighter? If it means a tight turning radius at low speed it was not. The Me 262 possessed a high turning rate (ie measured in degrees per second or time to complete a 360 degree circle) said the be better than a P-51 at height. Is the Griffon Spitfire a dog fighter? Apparently it wasn't a good idea to loop in it nor was it a good idea to loop in an Me 262.
The Me 262 possessed speed, good climb rate and excellent turn rate even if it could not turn in a tight radius.

The Me 262 was an interceptor, designed to intercept bombers and get through fighter screens to do so. I doubt it would have come of second best compared to a Meteor III so long as the Me 262 pilot played to his aircraft strengths which was about 12.5% speed. It certainly would have come of second best compared to the Meteor IV but then what could the Germans have achieved with the Me 262 by 1946? By that time there were advanced versions of the He 162, the Ta 183 and Arado 234C. Possibly with swept or scimitar wings.

My late 1945 I would have expected Me 410 style air brakes on the Me 262 and maybe 'area rule' bulges over the wings. 30,37,45 degree sweep versions were proposed. I don't know if the Germans would keep up with the rapid pace of Derwent development but they had a few more powerfull engines getting ready.

 

[Zyzygie]

Second is look at the speed the test was conducted at, which is 100ft/sec (ie 30m/s or 50km/h or 30mph).

I make 100 ft/s = 109.7 km/hr.

The bottom line though, I guess, is that Germany wasn't designing a Mach 1.3 aircraft in the middle of the War.

I do have to admit my admiration for a considerable number of German technological advances, but also look with disbelief at some of the idiotic stuff.

 

[Koopernic]

I make 100 ft/s = 109.7 km/hr.

The bottom line though, I guess, is that Germany wasn't designing a Mach 1.3 aircraft in the middle of the War.

I do have to admit my admiration for a considerable number of German technological advances, but also look with disbelief at some of the idiotic stuff.

The Metallurgical work in developing nimonic was brilliant. It seems Junkers went to Krupp and BMW to Bohler and picked their best heat resistance steal sheet stock and improved on that. Somehow Britain went with a tailor made alloy (it came out of electrical heating wire). Nickel, chromium and about 0.1% zirconium, which was a very important addition. Furthermore Whittle developed fir tree roots. The British blades were cast and then machined at great expense. I would be interesting to see how cromadur, tinadur or sciromal would perform with whittle style machined fir tree roots. He had intended to water cool the disk.

The Germans did pioneering work on air-cooling and heat and corrosion resistant coating and they would have succeeded with ceramics (they latterly did in 1946 design and in 1947 commission a power turbine that used the Jumo 004 compressor, ceramic inlet nozzles and water cooled turbine). Incidently J79 used ceramic turbine blades for the LP stage.

Eventually they would have gravitated towards fir tree roots but the moment they captured a Derwent theyd absorb the information very quickly.

The Germans were designing a supersonic aircraft in mid war. There was of course the manned V2 based reconnaissance rockets with their ram jet return, the Sanger Silverbird and the DFS 346 reconnaissance aircraft.

The German approach to supersonic flight was a high T tail aircraft to keep the horizontal tail out of the shock wave. The aircraft were designed as 'flying wings' with the horizontal tail there only for trimming purposes. The all flying tail developed for the Miles M.52 of course has become the standard though a few modern aircraft have used the high T tail approach. A refined Ta 183 might conceivably have gone supersonic in a dive. The Americans started out with V tails.

 

[Zyzygie]

On the development of Nimonic:
It seems that the alloy was first developed to meet high temperature exhaust valve application!

https://royalsocietypublishing.org/doi/pdf/10.1098/rsbm.1972.0016

 

[Zyzygie]

The Metallurgical work in developing nimonic was brilliant. It seems Junkers went to Krupp and BMW to Bohler and picked their best heat resistance steal sheet stock and improved on that. Somehow Britain went with a tailor made alloy (it came out of electrical heating wire). Nickel, chromium and about 0.1% zirconium, which was a very important addition. Furthermore Whittle developed fir tree roots. The British blades were cast and then machined at great expense. I would be interesting to see how cromadur, tinadur or sciromal would perform with whittle style machined fir tree roots. He had intended to water cool the disk.

The Germans did pioneering work on air-cooling and heat and corrosion resistant coating and they would have succeeded with ceramics (they latterly did in 1946 design and in 1947 commission a power turbine that used the Jumo 004 compressor, ceramic inlet nozzles and water cooled turbine). Incidently J79 used ceramic turbine blades for the LP stage.

Eventually they would have gravitated towards fir tree roots but the moment they captured a Derwent theyd absorb the information very quickly.

The Germans were designing a supersonic aircraft in mid war. There was of course the manned V2 based reconnaissance rockets with their ram jet return, the Sanger Silverbird and the DFS 346 reconnaissance aircraft.

The German approach to supersonic flight was a high T tail aircraft to keep the horizontal tail out of the shock wave. The aircraft were designed as 'flying wings' with the horizontal tail there only for trimming purposes. The all flying tail developed for the Miles M.52 of course has become the standard though a few modern aircraft have used the high T tail approach. A refined Ta 183 might conceivably have gone supersonic in a dive. The Americans started out with V tails.

The dreaded Starfighter used the high T tail...
But that's hardly an exemplar to follow:

The Tragic Reason Why Germany Hated Its F-104 Starfighters

As I understand it, at high angles of attack, the tail will possibly be in the turbulent wake of the main wing such that it tends to "stall" and lose lift.

 

[GrauGeist]

The F-104 was literally a manned rocket intended to climb and intercept Soviet bombers. It wasn't a fighter in the true sense, just as the Me262 was not a fighter, either - both were interceptors.

The fact that Germany had such an atrocious operational record doesn't necessarily fall on Lockheed, but rather how the Germans (out of all other nations) were operating their Starfighters.

Other nations that had the F-104 in their inventory had a far lower attrition rate, Italy even operating the Star fighter into the new century.

 

[Zyzygie]

The F-104 was literally a manned rocket intended to climb and intercept Soviet bombers. It wasn't a fighter in the true sense, just as the Me262 was not a fighter, either - both were interceptors.

The fact that Germany had such an atrocious operational record doesn't necessarily fall on Lockheed, but rather how the Germans (out of all other nations) were operating their Starfighters.

Other nations that had the F-104 in their inventory had a far lower attrition rate, Italy even operating the Star fighter into the new century.

Well OK GrauGeist. I'll take your word for it, but I did do a check which threw up this:

"...Aircraft with very short wingspans were susceptible to something called "inertia coupling". This was a problem encountered at high roll rates where the plane would yaw and pitch violently. To counter that, the Starfighter's horizontal stabilizer was mounted high up on the tail. In case you were wondering why they stuck it up there."
"In aircraft design, everything is a trade-off. At high angles of attack, that T-tail could be blanked out by the fuselage, causing a violent pitch-up and stall. The F-101 also had this problem. To warn the pilot that his F-104 was approaching the limit, it had a "stick shaker" similar to what airliners are equipped with. If he ignored the "shaker" he got the "kicker" which would forcibly push the stick forward. Since nothing is foolproof to a sufficiently talented fool, the kicker could be overridden by the pilot and hilarity would ensue..."
The not quite right stuff - F-104 Starfighter

But this is getting way off topic... Sorry

 

[Koopernic]

The dreaded Starfighter used the high T tail...
But that's hardly an exemplar to follow:

The Tragic Reason Why Germany Hated Its F-104 Starfighters

As I understand it, at high angles of attack, the tail will possibly be in the turbulent wake of the main wing such that it tends to "stall" and lose lift.

The Starfighter certainly had a potential superstall problem and used a stick shaker and stick pusher to try and prevent it.

The complete test crews of a BAC 1-11 and a Trident were lost to super stall (the 1963 Crickdale Incident) and a The 1966 Felthorpe Trident crash (on a delivery acceptance test)

However aerodynamic modifications to the BAC 1-11 and Trident eliminated the super stall problems and the Ilyushin IL-62 and Vickers Super VC10 never had it. Stick shakers and pushers were famously fitted but the problem was also dealt with aerodynamically.

Aircraft with swept wings can generate a forward pitching moment from their wings tips so long as they do not experience premature trip stall from span wise flow. Premature tip stall can be prevented with slats, dog tooth leading edges (VC10, Trident) etc.

Donald Douglass had Wing Fences and Vortilons fitted to the DC9 when he heard of the British incidents, So DC9 never had the issue.

An aspect of the super stall problem was that the engines would also stall from interrupted airflow which prevented the aircraft from powering itself out of the dive, so fences might be added to channel the airflow to the engines. BAC 1-11 and Trident had "auto light" so that the engines would automatically relight. (auto light lamps coming on were often the first indication of a stall)

However the German 'supersonic' aircraft would not have had 'super stall' because they were designed as flying wings with the tail there just for trim control. Imagine an Me 163 with a horizontal T tail.