"Cub Driver" wrote in message
...

The question is are we capable of producing
superior prop aircraft than the great fighters of WWII and what
configuration would it take?

I'm not sure what the engine would be. Is there an off-the-shelf
turbine engine that could be tweaked to the war-emergency power
requirements of a fighter aircraft?

I'm not saying there is none! I haven't the faintest idea of what
the
capabilities of existing turbines might be. But note that the
horsepower of front-line fighters in WWII was more than doubled in
four years, as an example of wartime requirements. Also, lives were
cheaper in those days.

The Germans accepted a man-killer like the Me
163 into front-line service, and the Me 262 would also be
unacceptable
today, with its 10-hour engine life.

The engine entered service with an MTBO of 25 hours which was well
established. (about 16 missions) Manufacturing complaince and service
realities degraded this to 10 hours for a while. Still if I was an
Ju 88 pilot I'd prefer converting to the Jet than the Me 109 given
that my combat skills and the concentraion of allied aircraft.

Mean time between overhall was 25 hours not total engine life and was
a problem of lack of chromium and particularly nickel at one level and
at another level poor manufacturing quality control compliance. (This
made the biggest difference; the use of unskilled factory labour
versus technicians and tradesmen who did not need supervision or
detail instructions)

Injector burners were the most heavily consmed item but could be
easily replaced.

The 6 Combustion chambers were made of simple carbon steel coated in
aluminium and needed to be replaced at 25 hours.

Both the hollow air cooled tinadur and cromadure turbine blades were
removed at 25 hours, x-rayed and if OK replaced for a further 10
hours.

Theoreticaly engine overhaul life reached 60 hours in the latter model
s.

Earlier engines, the Jumo 004B1 had solid blades while the Jumo 004B4
had hollow aircooled blades and was more reliable. The first
experimental blades had lives of 4 hours to over 100 hours due to
manufacturing spread.

What the Jumo 004B lacked was a throttle bypass system to bypass
excess fuel as the compressor spooled up. The control system did rely
on RPM and pressure but this was inadaquete in cases of rapid throttle
movement. The over supply of fuel could raise combustion temperatures
by 200C which had the effect of burning through combustion chambers
and turbines.

The BMW 003A used on the Arado 234C and He 162 volksjaeger despite
lagging 9 months behined and actualy having its control system derived
from the Junkers model was more sophisticated in having a throttle
bypass system.

The annular combustion chamber on the BMW 003A lasted 200 hours, the
turbine could be removed, inspected and replaced in less than 2
hours, the engine did have a throttle limiting system. Unlike the 004
the engine did not need to be stripped down.

The Jumo 004C and Jumo 004D both entered production (for use in
prototypes) and had increased thrust of 1050 and 1100kg due to detail
refinements. In the case of the 004D this included duel zone
combustion to overcome the atomisation problems that cuased flameouts
at high altitude and idling. (These engines all entered production
but not service. A Jumo 004C apparently propelled an Me 262 to
584mph.)

Part of the problem the engineers faced was the fuel. Although
designed for running on the diesel based J2 fuel for reasons of
economy and safety this added a 2 stage startup initialy on a lighter
fuel as well as necesitating fuel systems that could cope.

Some Me 262 missions were flown with crude oil in the tanks. The
crude oil was refined only by centrifuge, then heated and pumped into
the tanks.





all the best -- Dan Ford
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