F-35's Costs Climb Along With Concerns

Paul J. Adam wrote:
Packard cleaned up the castings, milled the mating faces approximately
flat (at least, compared to a metal-metal seal) and put a gasket between
them. I don't recall hearing tales of P-51s routinely or regularly
falling from the skies when their engines failed, nor of the Packard
Spitfires being execrated for unreliability (or, for that matter, lack
of horsepower).

Uh, I don't know about "regularly falling," but here is the best
reference I could find (skip down to the Mk XVI part):

http://www.spitfire.dk/chapter3.htm

I always figured this happened because of the difference between British
manufacturing (production tolerances designed for hand-fitted assembly,
ie. not all pistons will fit well in all cylinders) vs American
manufacturing (production tolerances matched for mass production, ie.
all pistons will fit well enough in all cylinders).

Then again, the article I cited suggests it may have been a problem
limited to just one batch rather than the different industrial
philosophies between Henry T. and Henry Royce.

Was this thread about the F-35?

"Paul J. Adam" wrote:

In message , Ricardo
writes
Incidentally, a few sources have claimed that the Packard built Merlin,
whilst a superb engine, lacked the power levels of the Rolls Royce
version. This, it is claimed, was because the British kept secret the
composition of the phosphor-bronze bearings that they used in the
engine. No, I can't quote a source/s.

On the other hand, I heard - from "old factory hands" lecturing on
manufacturing technique at Highbury College in 1988 - that a big
difference between Packard and Rolls-Royce was in fitting the cylinder
head.

Rolls-Royce used a precision hand-scraped metal-to-metal fit. Very
effective, though extremely demanding in scarce skilled labour.
(Attempting to 'file flat' is a useful exercise for a trainee mechanical
engineer; it teaches a certain humility in demanding surface finishes)

Packard cleaned up the castings, milled the mating faces approximately
flat (at least, compared to a metal-metal seal) and put a gasket between
them. I don't recall hearing tales of P-51s routinely or regularly
falling from the skies when their engines failed, nor of the Packard
Spitfires being execrated for unreliability (or, for that matter, lack
of horsepower).

I think it's fair to say that Packard 'productionised' the design of the
Merlin which made it easier and quicker to build, possibly more reliable
too.

Graham

Paul J. Adam wrote:
Packard cleaned up the castings, milled the mating faces approximately
flat (at least, compared to a metal-metal seal) and put a gasket between
them. I don't recall hearing tales of P-51s routinely or regularly falling
from the skies when their engines failed, nor of the Packard Spitfires
being execrated for unreliability (or, for that matter, lack of
horsepower).

A family friend, now departed, was a wrench-turner on (American)
Merlins during the war. He always said the Packard was easier to
work on, but did not take damage as well as, the RR version. His
reasoning was that, where RR might use (arbitrarily, as I can't recall
his exact words) 30 bolts spaced closely to attach an exhaust manifold,
Packard would use 20 spaced farther apart. He said that he saw
cases where Packard and Rolls-Royce engines would come back
with near-identical damage and the genuine article could still produce
power.


Jeff

My father-in-law had a similiar experience here in Canada. In circa
1942 he was an apprentice machinist for a new factory tasked with
manufacturing a British 4.5" naval gun design. IIRC, the original
British procedure for any shaft/bushing was to machine the shaft with
0.020 in interference and the hand file the shaft to fit. As he said,
there wasn't one in a hundred in their labour pool that could do this.
Part of his job was developing new dimensions and tolerances to allow
parts to be manufactured independently, inspected for dimensions, and
then assembled without further machining.

"Paul J. Adam" wrote in message
...
In message , Ricardo
writes
Incidentally, a few sources have claimed that the Packard built Merlin,
whilst a superb engine, lacked the power levels of the Rolls Royce
version. This, it is claimed, was because the British kept secret the
composition of the phosphor-bronze bearings that they used in the engine.
No, I can't quote a source/s.

On the other hand, I heard - from "old factory hands" lecturing on
manufacturing technique at Highbury College in 1988 - that a big
difference between Packard and Rolls-Royce was in fitting the cylinder
head.

Rolls-Royce used a precision hand-scraped metal-to-metal fit. Very
effective, though extremely demanding in scarce skilled labour.
(Attempting to 'file flat' is a useful exercise for a trainee mechanical
engineer; it teaches a certain humility in demanding surface finishes)


When I started work as an engineering apprentice at ICI they still
sealed the main steam joints on the turbines in the power station
this way. It isnt the file flat that's so time consuming as the
scraping of the surface until its flat according to the reference
surface plate.

They now use a lapping machine and gasket and its no less
reliable and a LOT quicker, plus I doubt there are many
fitters around with the skills to scrape joints flat any more.

Keith





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In article ,
(Ricardo) wrote:

Incidentally, a few sources have claimed that the Packard
built Merlin, whilst a superb engine, lacked the power levels
of the Rolls Royce version. This, it is claimed, was because
the British kept secret the composition of the phosphor-bronze
bearings that they used in the engine.

The Packard Merlin did differ as far as I know but also as far
as I know it was not because of secrets. The British versions
were to closer tolerances requiring much more skill in assembly.
In "Sigh for a Merlin" a fault called skew gear failure was
traced to a difference in assembly order from Rolls Royce in one
of the (British) shadow factories.

Ken Young

wrote:
In article ,
(Ricardo) wrote:


Incidentally, a few sources have claimed that the Packard
built Merlin, whilst a superb engine, lacked the power levels
of the Rolls Royce version. This, it is claimed, was because
the British kept secret the composition of the phosphor-bronze
bearings that they used in the engine.


The Packard Merlin did differ as far as I know but also as far
as I know it was not because of secrets. The British versions
were to closer tolerances requiring much more skill in assembly.
In "Sigh for a Merlin" a fault called skew gear failure was
traced to a difference in assembly order from Rolls Royce in one
of the (British) shadow factories.

In fact the Rolls Royce tolerances were rather looser than those
used by either the British Ford Motor Company or Packard. Rolls
Royce used hand fitting to match up parts, whereas Ford and Packard
were mass production companies which relied on close tolerances so
that parts were interchangeable without the laborious fitting and
adjusting that Rolls Royce used. The Rolls Royce system did require
a higher skill in assembly due to these fitting requirements.

Mike

In article , Ricardo
wrote:

The initial air assaults on Britain dispelled the myth that dive bombing
was the way forward as in the face of determined fighter opposition the
dive bombers did not fare too well - despite how well it had done in
Spain and against the low countries of Europe.

Conventional bombing was more the norm for the Battle of Britain and the
service ceiling of the German bombers was between 25,000 and 30,000
feet, and for their escorting fighters between 35,000 and 40,000 feet,
although operationally they were likely to be a lot lower. Nonetheless
height is a crucial factor in aerial warfare and if you are 10,000 feet
above your enemy you are more likely to inflict damage and survive than
if you are 5,000 feet below him and desperately climbing to reach him.


Ricardo, I believe that your figures are uniformly 10,000 feet too high.
All the reports that I've read for the BoB mention the bombers coming in
between 15 and 20 thousand with fighter cover about 5 thousand higher.
After the BoB altitudes went higher, that was one of the lessons learned.


At the height of the Battle of Britain the country's desperate need was
for fighter aircraft - any fighter aircraft - hence purchases from
American sources. However, by the time the early Mustang came on stream
that particular battle was virtually over, allied with which British
built fighter production had gained considerable momentum.

Yet the Mustang I's equipped a large number of squadrons.

--
Harry Andreas
Engineering raconteur

Harry Andreas wrote:
In article , Ricardo
wrote:


The initial air assaults on Britain dispelled the myth that dive bombing
was the way forward as in the face of determined fighter opposition the
dive bombers did not fare too well - despite how well it had done in
Spain and against the low countries of Europe.

Conventional bombing was more the norm for the Battle of Britain and the
service ceiling of the German bombers was between 25,000 and 30,000
feet, and for their escorting fighters between 35,000 and 40,000 feet,
although operationally they were likely to be a lot lower. Nonetheless
height is a crucial factor in aerial warfare and if you are 10,000 feet
above your enemy you are more likely to inflict damage and survive than
if you are 5,000 feet below him and desperately climbing to reach him.



Ricardo, I believe that your figures are uniformly 10,000 feet too high.
All the reports that I've read for the BoB mention the bombers coming in
between 15 and 20 thousand with fighter cover about 5 thousand higher.
After the BoB altitudes went higher, that was one of the lessons learned.



At the height of the Battle of Britain the country's desperate need was
for fighter aircraft - any fighter aircraft - hence purchases from
American sources. However, by the time the early Mustang came on stream
that particular battle was virtually over, allied with which British
built fighter production had gained considerable momentum.


Yet the Mustang I's equipped a large number of squadrons.

Hi Harry,

I was quoting the maximum operating heights for the categories of
aircraft but concede that much of the action took place at lower level.

The Mustang was not a participant in the Battle of Britain and, as far
as I'm aware was used for 'army liaison duties' with the Army
Co-operation Command which was established in December 1940 and also
with the Combined Operations Unit. The first Mustang to arrive was on 24
october 1941.

Ricardo

"Ricardo" wrote in message
k...


Harry Andreas wrote:
In article , Ricardo
wrote:


The initial air assaults on Britain dispelled the myth that dive bombing
was the way forward as in the face of determined fighter opposition the
dive bombers did not fare too well - despite how well it had done in
Spain and against the low countries of Europe.

Conventional bombing was more the norm for the Battle of Britain and the
service ceiling of the German bombers was between 25,000 and 30,000 feet,
and for their escorting fighters between 35,000 and 40,000 feet, although
operationally they were likely to be a lot lower. Nonetheless height is a
crucial factor in aerial warfare and if you are 10,000 feet above your
enemy you are more likely to inflict damage and survive than if you are
5,000 feet below him and desperately climbing to reach him.



Ricardo, I believe that your figures are uniformly 10,000 feet too
high.
All the reports that I've read for the BoB mention the bombers coming in
between 15 and 20 thousand with fighter cover about 5 thousand higher.
After the BoB altitudes went higher, that was one of the lessons learned.



At the height of the Battle of Britain the country's desperate need was
for fighter aircraft - any fighter aircraft - hence purchases from
American sources. However, by the time the early Mustang came on stream
that particular battle was virtually over, allied with which British
built fighter production had gained considerable momentum.


Yet the Mustang I's equipped a large number of squadrons.

Hi Harry,

I was quoting the maximum operating heights for the categories of
aircraft but concede that much of the action took place at lower level.

The Mustang was not a participant in the Battle of Britain and, as far
as I'm aware was used for 'army liaison duties' with the Army
Co-operation Command which was established in December 1940 and also with
the Combined Operations Unit.

Only true in regards to the Mustang I and IA; the later Mustang III served
with a number of RAF units in the (primarily) air-to-air fighter role and
performed escort for both USAAF and RAF bombing missions. P-51D/K variants
served with the RAF for a couple of years after the war was over.

Brooks
The first Mustang to arrive was on 24
october 1941.

Ricardo