"Emmanuel Gustin" wrote in message ...

"John Freck" wrote in message
om...

I know people at work who can assemble an engine. Being
able to assemble an engine is very basic to the 'mechanic'.

An aircraft engine is not a car engine. Car engines are heavily
built and with fairly robust tolerances; they are designed to
run almost forever. WWII aircraft engines were running very
close to material limits, and keeping them operational would
be more akin to tuning the engine of a Formula 1 racing car
than to car-type maintenance. They were also extremely complex
by modern standards. These days, assembly of WWII engines is
limited to a handful of specialised workshops.




Why did you write the above? Today, a corporation specialized to
manufacturing small propeller aircraft for the leisure and corporate
market does exist. I bet there is more than one company making
propeller aircraft.
I will Google for a few minutes in a new window.


To give an extreme example, Rolls-Royce once traced back
a series of Vulture engine failures, resulting in fatal crashes,
to the fact that the connecting rod bolts were tightened unevenly
and at a too high tension, exceeding material limits at high rpm.
Every engine had to be removed from the aircraft and sent
back to the factory, where new bolts were installed and tightened
to exact the right tension (which was lower than the original
design value).



Why did you post the above information? Are you supporting the notion
that important and large fighters could not be built on and/or near a
large W.W.I.I. airbase. I don't think every dinky airbase had
manufacturing of complete planes.


Your question specifically referred to assembling a new engine
from parts of *damaged* engines. This would be an extremely
foolhardy procedure, as absence of superficial damage would
by no means guarantuee that parts were still up to design strength.


So there was no recycling? Are you arguing purely from a conceptual
frame of reference?


More stuff for small to medium businesses that make moving metal
parts.

So what? Engines would not merely need acurately turned and
milled parts, they would have to be made of the right alloy and
receive exactly the correct heat and surface treatment. To take
an example of a seemingly simple but extremely demanding part,
the sleeves of Bristol sleeve-valve engines were finished to an
accuracy of two ten-thousandths of an inch in bore, with deviations
of cylindrical shape not exceeding 1/1000 inch over the whole
14-inch length of the sleeve. The process involving milling,
grinding, lapping, and nitritiding to harden the surface. Bristol
actually had to design and build their own tools to succeed in this.



Why can't all of that be done near an airport/airbase? You too are
putting forward and defending the odd concept that it is conceptually
unattainable for planes to be assembled near airports. Are you really
thinking things thru?



The feeder factories are smaller and more numerous than you imagine.

Of course the major engine manufacturers used subcontractors,
hundreds of them, but usually under tight control. The entire
production process was very carefully checked. An Allison
V-1710 had about 7000 parts; but 70,000 inspections were
done, at every stage of production and after the test run, before
the engine was passed. These inspections accounted for 20%
of the workforce.


Are you too putting forward the concept that the USAAF can't gather,
cultivate, and grow the sort of labor you indicate a fighter plane
makers would have?


In fact suitable "feeder factories" were often far too few in
number. A good example is the so-called "Vickers unit", an
hydraulic motor used in Sperry gun turrets, manufactured to
extremely high tolerances to get accurate turret control, and
costing $ 1400 per unit. The Production Engineering Section
of the USAF minuted "it has proven impossible to find a
manufacturing source to augment the two existing sources".
Actually the second of these could play a role only because
the USAF had relaxed the pass criteria for these units; and
at the end of the war attempts to design a replacement part
that was easier to manufacture had not produced useful
results.

http://www.naplesnews.com/03/09/florida/e5099a.htm
A manufacture of propeller dirve planes employs 720 workers
at a manufacturing plant. This plant use 99 acres.
It is adjectent to a small airport which is much small that a large
USAAF airbase of WWII.
http://www.azworldairports.com/airports/p2740vrb.htm

I don't understand the conceptual problem some have with warplanes
being assemble, or built, or recycled, or reconstruted, or what have
you
near or on a military base. Many workers at the Piper Plant of Vero
Beach
learned their skills in the US military too. I think a Piper is the
closest thing to
a WWII fighter in commercial production today.

John Freck