soc.history.war.world-war-ii

wrote in message
news:ed8f577f-585e-418d-a8f3-3b0800337914@p73g2000hsd.googlegroups.com...
> On Feb 26, 5:04 pm, "Geoffrey Sinclair"
> wrote:
>> wrote in message

>> > In Monogram Aviations Book (by J Richard Smith and Eddie L Creek) on
>> > the Arado Ar 234 Jet it is mentioned that the controls had a slight
>> > 'sticky' feel from the substitution of sleeve bearings for ball
>> > bearings. This compromise had to be made on one of Germany's newest
>> > and most important weapons.
>>
>> This is for something being built in 1944 1945 amid significant
>> production and transport difficulties.
>>
>> This is despite the allies deciding hitting the ball bearing works
>> was not the answer. Could it have something to do with the
>> massive production expansion of existing fighter designs causing
>> further shortages and a reaction to the 1943 and early 1944
>> attacks on ball bearing works?
>
> Bearing production due to the raids on Schweinfurt was disrupted, yet
> it was eventually restored, Had it never been disrupted by bmbing it
> could have been further expanded rather than merely restored.

I have no problems with the reality the raids disrupted production
but that the factories could be repaired, as the USSBS says on ball
bearings,

"Although there were further attacks, production by the autumn of
1944 was back to pre-raid levels. From examination of the records
and personalities in the ball-bearing industry, the user industries and
the testimony of war production officials, there is no evidence that
the attacks on the ball-bearing industry had any measurable effect
on essential war production."

So how does the idea the raids stopped expansion supposed to work?
Given the raids forced a concentration on the industry and resources
made available on the basis it was under attack, just like from mid
1944 onwards the oil industry received large extra resources.

>> > The Heinkel HeS 30 (technically Reichs Luftfahrts Ministeriums)
>> > designation 109-006 was a turbojet developed at Heinkel by Max Adolf
>> > Mueller after he had been attracted away from the Junkers Airframe
>> > division where he had been working on jet engine concepts. (The Junkers
>> > Jumo 004 came out of the more stodgy engine division).
>>
>> Note the change of location set back research and the promised
>> development times were missed.

These being an important part of the decisions taken.

>> > This
>> > remarkable engine was not exceded in performance by any other engine
>> > in the world till 1947.
>>
>> http://www.reference.com/browse/wiki/Heinkel_HeS_30
>>
>> " It produced a thrust of 860 kg, about the same as contemporary designs,
>> but weighed only 390 kg, providing a much better power to weight ratio.
>> The engine also had better specific fuel consumption and was smaller in
>> cross-section as well. It has been said that the overall performance was
>> not matched until 1947."
>>
>> Not the rewrite from it is said to it definitely was.
>
> I have found no engines that match it for Thurst to Weight Ratio till
> the J-35 of 1947 though the task is difficult due to the need to nail
> down exact dates.

I simply note the change from reference to claim made.

> The whittle style rolls royce engines with the
> double impeller can match it in Thrust to Weight ratio earlier but
> must bow down by a much larger frontal surface area.

Yes we know the idea is to come up with a set of criteria that
ensures the Heinkel engine is the best.

>> > Performance being measured by high thrust to
>> > weight ratio, low frontal area to thrust ratio and low specific fuel
>> > consumption. At 1125 kg thrust it weighed only 390kg compared to the
>> > Jumo 004B's 900kg thrust for 720kg thrust.
>>
>> Except that when the HeS 30 engine was abandoned as a major effort
>> in 1942 the thrust was 860 Kg.
>
> Still impressive 860kg/390kg about 2.25:1

Just that the real thrust is about 75% the real one. If the engine was
that good why the need to boost the figures even more?

>> The Juno 004 B came in at 900 kg thrust for 808 kg dry weight.
>
> The dry weight was about 722-730kg. The weight of 805kg is the dry
> cowled weight.

Ah the usual difference in references.

>> The Heinkel engines were behind the Jumos when it came to appearing
>> ready for production.
>
> Not by much in reality since the HeS 030 ran in late 1941 and the the
> non production Jumo 004A didn't run a year earlier in late 1940 and it
> didn't excede 600kg thust till Jan 1941 and its radically re-
> engineered and productionised version didn't enter service till mid
> 1944.

So let me understand this, in late 1941 the Jumo had been running
for about a year. But this is not really behind the Heinkel engine?

Try 004A first run in October 1940, and had reached 430 Kg
thrust in January 1941 and 600 kg in August 1941. First test flight
in March 1942.

The 004B basic design was done by December 1941, with test
runs being done in December 1942. Trail production versions in
May or June 1943.

Simply put in late 1941 and early 1942 the Heinkel engines were
assessed as being further from production.

> The HeS 030 superior compressor technology would have allowed a
> reduction in exhaust gas temperature so as to trade reliability for
> lower thrust or lower grade materials.

Yet the design was abandoned, even knowing the problems of
providing the high temperature resistant materials. Perhaps the
engine had problems? Or is the idea the Luftwaffe was wrong again?

> BMW and ABB both developed
> such compressors for the 800kg thust BMW 003 which was expected to
> achieve 900kg thrust and 1100kg thrust. (these were the Bmw 003C AND
> bmw 003D)

Ah yes, the engines that never were are used as proof again.

>> (snip)
>>
>> See the web page since the rest of the post is a paraphrase.
>>
>> Note in the 1942 period the Germans were not short of bearings.
>
> Define shortage.

When Speer ordered the urgent action after the first Schwienfurt
raids it was discovered just how big the industry stocks had become.
They had a really big cushion to cover any production shortfalls.

So with industry accumulating stocks how exactly is it possible to
declare a shortage?

Plus there was supply from neutrals.

> Improving production efficiency (ie less bearings)
> at the design phase was already a big theme despite the received
> wisdom which claims that the war economy proper didn't start till
> 1943.

So the below can be shown to reduce bearing usage, or is it
simply a set of claimed good decisions?

> There were for instance shortages of Daimler Benz engines,

In the late 1930's delivery causing delays in the Bf109 and Bf110
programs and meaning other aircraft had to source other engines.

> the
> Bf 109 won over the He 112 in part due to its greater ease of
> production,

In part due to performance. I have no problems the Germans in
the 1930's started thinking in terms of mass production of aircraft
before other European powers, the Ju88 is another example. The
reality was they were supplying a government determined to create
a very large military, everyone else was hoping for business as usual,
or at least a modest German armaments program.

> the Me 410 use welded engine mountings instead of the
> usual German elektron forgings since it was feared that the big
> presses would become a target for bombers.

So is the idea the welded mountings were more efficient which makes
the standard forgings method wasteful?

Geoffrey Sinclair
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