soc.history.war.world-war-ii

On Feb 26, 5:04 pm, "Geoffrey Sinclair"
wrote:
> wrote in message
>
> news:1d00f2e4-e5c8-496f-b861-f58a7c6f927e@s19g2000prg.googlegroups.com...
>
>
>
> > On Feb 19, 8:14 am, "ianf" wrote:
> >> Hello...
> >> I was watching the World at War episode on strategic bombing, and I
> >> was intrigued by a statement from Albert Speer regarding the effects
> >> of the 1943 raids on Schweinfurt. At one point he iterated how
> >> devestating they were, but that his assistant Kessler (or Hessler, not
> >> sure) was able to obtain "other devices that would do the job of a
> >> ball bearing, not as well but they would do the job."
>
> >> I wondered what he was referring to.....oil impregnated bearings or
> >> something?
>
> >> Anyone have a clue?
>
> > 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.


>
> > 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.
>
> > 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. 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.



>
> > 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

>
> 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.


>
> 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. 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. 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)

>
> (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. 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. There were for instance shortages of Daimler Benz engines, the
Bf 109 won over the He 112 in part due to its greater ease of
production, 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.





>
> Geoffrey Sinclair
> Remove the nb for email.