British v. German jet engines (Pete Stickeny)

Pete Stickney wrote in another thread:

(The Aliies, after all, succeeded in 1943 in
producing what the Germans could not - practical, reliable jet engines
that could be flown for more than a day before needing to be
overhauled, and which could be worked on by typical mechanics. Before
the Me 262 appeared in 1944, both the Americans and the British were
running engines with more than twice the thrust, and 10 times the life
of the best realized German efforts.)

Pete, the rough figures I carry in my mind is 10 hours TBO for the
Jumo engine in the Me 262 and 25 hours for the GE? engine in the P-80.
I have also seen 50 hours mentioned in a 1945 briefing about the P-80.

I'd be grateful if you could flesh out the parenthesis. The only
engine I know anything about is the Whittle turbojet as modified by GE
for the Bell YP-59A. I never followed up on what changed before the
P-80 got running.

And what about that P-80? It seems to have had an unwonted number of
crashes for an airplane that turned into the longest-serving jet ever
built (still in service, as I understand, as the T-33 in recce and
light-attack roles for various air forces).

Thanks!

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
Expedition sailboat charters www.expeditionsail.com

"Cub Driver" wrote in message
...

Pete Stickney wrote in another thread:

(The Aliies, after all, succeeded in 1943 in
producing what the Germans could not - practical, reliable jet engines
that could be flown for more than a day before needing to be
overhauled, and which could be worked on by typical mechanics. Before
the Me 262 appeared in 1944, both the Americans and the British were
running engines with more than twice the thrust, and 10 times the life
of the best realized German efforts.)

Pete, the rough figures I carry in my mind is 10 hours TBO for the
Jumo engine in the Me 262 and 25 hours for the GE? engine in the P-80.
I have also seen 50 hours mentioned in a 1945 briefing about the P-80.


Dont know about the GE engines but the Wellands used by the
Meteor in 1944 were rather conservatively rated at 180 hours

http://www.enginehistory.org/r-r_w2b.htm

IRC the first production Welland ran for around 2000 hours
on the test bed.

Keith



I'd be grateful if you could flesh out the parenthesis. The only
engine I know anything about is the Whittle turbojet as modified by GE
for the Bell YP-59A. I never followed up on what changed before the
P-80 got running.

And what about that P-80? It seems to have had an unwonted number of
crashes for an airplane that turned into the longest-serving jet ever
built (still in service, as I understand, as the T-33 in recce and
light-attack roles for various air forces).

Thanks!

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
Expedition sailboat charters www.expeditionsail.com

"Keith Willshaw" wrote in message ...
"Eunometic" wrote in message
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Cub Driver wrote in message
. ..
Pete Stickney wrote in another thread:


These allied engines were so succesfull and powerfull that non of them
could be installed on an aircraft. irony off


What propelled the Meteor then ?

Rubber bands ?

The Welland of the Meteor I could, admitedly, outperform a rubber band

The Meteor III improved the situation but was still no faster than a
top line piston fighter at altitude. (TA 152H, P51H, Spitefull, Do
335, P47M)





Keith

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"Keith Willshaw" wrote in message
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Cub Driver wrote in message
. ..
Pete Stickney wrote in another thread:


These allied engines were so succesfull and powerfull that non of them
could be installed on an aircraft. irony off


What propelled the Meteor then ?

Rubber bands ?

The Welland of the Meteor I could, admitedly, outperform a rubber band

The Meteor III improved the situation but was still no faster than a
top line piston fighter at altitude. (TA 152H, P51H, Spitefull, Do
335, P47M)


Meteor III was considered superior to the Tempest V in all depts
except for roll rate, the Meteor III's with long nacelles were faster
than the Me-262 and the Meteor IV's were capable of 580 mph

Keith




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"Keith Willshaw" wrote in message ...
"Eunometic" wrote in message
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Cub Driver wrote in message
. ..
Pete Stickney wrote in another thread:


These allied engines were so succesfull and powerfull that non of them
could be installed on an aircraft. irony off


What propelled the Meteor then ?

Rubber bands ?

The Welland of the Meteor I could, admitedly, outperform a rubber band

The Meteor III improved the situation but was still no faster than a
top line piston fighter at altitude. (TA 152H, P51H, Spitefull, Do
335, P47M)


Meteor III was considered superior to the Tempest V in all depts
except for roll rate, the Meteor III's with long nacelles were faster
than the Me-262 and the Meteor IV's were capable of 580 mph

Keith


The Meteor was a well designed aircaft but it did require a lot more
thrust and development to actualy perform as a 'fast Jet' and clearly
the concept lived on in the Canberra bomber with its high speed and
high altitude but it was intrinsically a transonic aircraft.

Its also inplausible to assume that Messerschmitt would have been
siting on its hands with Me 262A1a fitted with 880kg thrust Jumo 004B1
while the British developed Meteor I, Meteor III, Meteor III long
nacelle etc.

The Jumo 004C increased thrust to 1000kg pushing the Me 262 top speed
to 578mph (its record level flight speed), while the Jumo 004D pushed
the thrust to 1050kg.

At that point the much lighter and much much smaller frontal area
BMW003D at 1100kg thrust might have been ready with its much better
fuel consumption and lower drag and latter still the Me 262 with
Heinkel Hirth HeS 011 with 1300 (hopefully raising to 1700kg)
turbojets installed in the armpit position. (the BMW003D was needed
for long range reconaisence versions of the Arado 234)

(Peter Stickney) wrote in message ...
In article ,
Cub Driver writes:

Pete Stickney wrote in another thread:

(The Aliies, after all, succeeded in 1943 in
producing what the Germans could not - practical, reliable jet engines
that could be flown for more than a day before needing to be
overhauled, and which could be worked on by typical mechanics. Before
the Me 262 appeared in 1944, both the Americans and the British were
running engines with more than twice the thrust, and 10 times the life
of the best realized German efforts.)

Pete, the rough figures I carry in my mind is 10 hours TBO for the
Jumo engine in the Me 262 and 25 hours for the GE? engine in the P-80.
I have also seen 50 hours mentioned in a 1945 briefing about the P-80.

The 10 hour TBO for a Jumo 004 is rather misleading. According to
Aircraft Engineering's analysis of the Jumo 004B, you had to drop the
engine set somewhere between 6 and 10 hours for a teardown and
mandatory turbine wheel replacement. (Which was a shop job, and
couldn't be done in the field. Balancing the compressor-turbine rotor
was critical, adn was a hand-fit job). The burner canse were also
checked and replaced as needed at the same time. You ran it for
another 5-10 hours, and threw it away.

The BMW003 was a far more impressive engine in terms of service than
the Jumo 004 despite being introduced into service latter.

There were also several variants of the Jumo 004 with different
serviceabilities.

The first engines captured by the allies (An Arado 234 of III.KG76)
were the Jumo 004B1 which although the main production engine didn't
have the hollow turbine blades yet and also had compressor vibration
problems)

The next production series that entered service, the jumo 004B4, (B2
and B3 never entered mass production) introduced hollow turbine blades
and changes in cooling bleed air and combustion system as well as
solved compressor vibration problems. These changes were capable of
increasing thrust via a greater exhaust temperature but the the
potential improvements were eschewed to improve service life
considerably.

The combustion chambers were made of ordinary steel treated with an
aluminium oxide to reduce corrosion. They were being continiously
inproved with new gas flows and cooling film systems.

Had they been made of even ordinary stainless steel they would have
had a vastly increased service life.

The engine used two types of hollow turbine blades of the alloy
tinadur or cromadur. Tinadure Bladed engines used ony 6.5kg of
nickel and 4.6kg of chromium and 0.2kg of molydenum (for the whole
engine). cromadure bladed Jumo 004B4s used only 3.5kg kg of nickel
and 4.7kg of chromium and 0.2kg of molydenum (for the whole engine)

There must have been nearly a hundred kg on an allied engine!

The Jumo 004C made further improvements in service life as well as
sericeabillity and was in mass production when the war ended.

One thing that also has to be remembered was that the confusion and
paucity of raw materials often led to inproper substitution that
reduce engine life. In the case of one raw material on the BMW 003 it
was changed seven times such was the confusion at the end of the war.

The Jumo 004B had accesibility problems to the combustion chambers
which meant that the engine had to be dropped down from the aircraft
to be replaced. The life nvertheless reached 60 hours at the end of
the war.

The Powerjets (whittles company) analysis of the first Jumo 004B1
engines indicates that if a higher level of supply of nickel could be
achieved these engines would improve. One important technique was to
pull a violin bow over the turbine blade to make sure they had been
soldered into the roots properly (this was a critical point of
failure)

The BMW003A1/A2 had a very reliable combustion chamber which lasted
200 hours. The turbine entered service with a MTBO (service of
replacement was in the field and on the wing) of 20 hours and ended up
with 50 hours without trouble: the limitation being the attachments of
the turbine to the disk.

The Anular combustion chamber must have been the most impressive of
any WW2 engine as it ahieved a gas velocity of only 110 m/s.

It appears that BMW was about to receive an order to develop the BMW
P3006; a scaled up BMW003 of 1700kg thrust.


The early J33s get hot section inspections every 25-50 hours. You
split the airplane and looked at the turbine blades with a borescope.
(P-80 tails came off as a unit to give full access to the engine -
It's not a big job - I've seen T-33s (The same airplane, at that
point) done in about an hour. TBO was originally set for 100 hours,
and that was bumped up to 400 hours after the war. In 1950-51,
according to the AIAA Yearbook, they bumped it up to 1,000 Hrs.

The J35, the Axial that GE also developed in the 1944 timeframe,
started with about a 25 Hr TBO, which was gradually incresed to 500
Hrs before the Korean War. (Save for one batch that used farm
machinery bearings, and those didn't last long). Post Korea, J35 TBO
was increased to more than 1000 Hrs.

The Rolls Nene/Pratt & WHitney J42 started with a 250 Hr TBO, and
this was increased to 1000 Hrs in 1949.

It ought to be noted that the big recips, especially those used on
fighters, were usually pulled for overhaul every 100-150 Hrs.

I'd be grateful if you could flesh out the parenthesis. The only
engine I know anything about is the Whittle turbojet as modified by GE
for the Bell YP-59A. I never followed up on what changed before the
P-80 got running.

Basically, the engines got bigger, and ran hotter. The biggest
changes on the Allied side were in the areas of the fuel controls.
Originally, the pilot directly controlled fuel flow with the
throttle. That's doable, but the engine required a widely varying
fuel flow depending on speed and altitude. (The faster you go, the
more air you're using, and the more fuel you have to burn. The higher
you go, the less fuel you burn becasue of the lower density.) The
pilot also had to moniter the turbine temperature (Gas temperature
after the turbine, usually (TET - Turbine Exit Temperature) which
stays pretty fixed with the critical TIT (Turbine Inlet Temperature),
adn the engine RPM to make sure he wasn't exceeding any
limits. (Exceeding limits would casue the turbine wheel to come
apart). Fast throttle movements could very easily lead to an
overtemperature, or flame the engine out. Improved fuel controls were
little hydromechanical analog computers that monitored the various
parameters, adjusted things to meed the pilot's demands for power, and
controlled the fuel flow accordingly. The Brits actually ended up
with a lead in this area until the early '50s.

And what about that P-80? It seems to have had an unwonted number of
crashes for an airplane that turned into the longest-serving jet ever
built (still in service, as I understand, as the T-33 in recce and
light-attack roles for various air forces).

I've just done some poking around, and I don't see that the P-80's
accident rate was any worse than that of any contemporary fighters.
P-61s had an accident rate of about 120/100,000 hrs, and they wer the
safest of the bunch. (The worst were P-39s, with a rate of
249/100,000 flt hrs).

There were accidents with the early jets that were certainly due to
their "jet-ness", if you will. A case in point was Richard Bong's
crash. He took off in a P-80 without turning on the alternate fuel
booster pump. (A checklist item) just after takeoff, the fuel control
packed it in, and he ended up flaming out. As I've alluded to before,
jets don't decelerate like recips. Even the early jets were very
clean (Almost like sailplanes) and, until you got into the transonic
range, there wasn't a whole lot of drag. With prope it's different -
when you pull back on the power, you get a big increase in drag as the
slipstream tries to drive the prop. That makes formation flying, or
entering the landing pattern, a lot easier. The low drag also meant
that when you pointed the nose down, the jet accelerated like a rock.

The early jets also were quite underpowered at low speeds (That
thrust/horsepower thing) and the engines didn't respond quickly - 8-16
seconds from Flight Idle to Max Power wasn't unusual. So they didn't
accelerate well at all. Paradoxically, though, once they got going,
it didn't take long before they were pushing into the transonic range,
and things would really get squirrely. (Roland Beamont established
the maximum Mach Number for the Meteor IV's speed record by entering
the Meteor's Mach Tuck (Meatboxes would nose down) at roughly 610 mph
and 50 ft altitude.) Vampires would porpoise, banging on alternating
postive and negative G until something broke. Venoms would lose all
elevator control. P-80s would buffet like mad, and the elevator
effectiveness would decrease. F-84s (The straight winged ones) would
pitch up at something like 7 or 8 Gs. Unlike piston engined
fighters, these airplane could reach that region in level flight, on a
good day. So yo couldn't just hop into one and fly it - you had to
develop a whole new set of reflexes. That was one of the reasons that
Lockheed stretched the F-80 into the TF-80C/T-33.
Jets can be deceptively easy to fly - they're very smooth, there's no
torque, and there's only one power lever to worry about, rather than
the handful of stuff that goes with, say, a Merlin or R2800. But they
can also get you into trouble fast, and booouncing around in teh Mach
Buffet at 10,000' with the nose 45 degrees below the horizon is no
place for On the Job Training.

On 10 Aug 2004 00:32:05 -0700, (Eunometic)
wrote:

The life nvertheless reached 60 hours at the end of
the war.

Huh. The Messerschmitt test pilots who flew the 262 for the Americans
in May 1945 claimed a TBO of 25 hours.

How did one know which engine was in a given aircraft? Was the TBO
stamped on it?

all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
Expedition sailboat charters www.expeditionsail.com

Cub Driver wrote in message . ..
On 10 Aug 2004 00:32:05 -0700, (Eunometic)
wrote:

The life nvertheless reached 60 hours at the end of
the war.

Huh. The Messerschmitt test pilots who flew the 262 for the Americans
in May 1945 claimed a TBO of 25 hours.

How did one know which engine was in a given aircraft? Was the TBO
stamped on it?

There were several production versons: the Jumo 004B1 which had solid
tinadur (about 40% iron, 30% titanium, 15% nickel, 15% chromium)
turbine blades then the much improved Jumo 004B4 which could have
hollow turbine blades of either deep drawn tinadur or folded and
welded cromadure ( about 68% Iron, 14% chromium and 18% manganese) and
other changes to combustion and copressors.

The reason was that the Germans had the two types made as backups to
each other and neither company could supply sufficient blades alone.
cromadur was supposedly inferior due to higher creep but it was
actualy more reliable in service because its process of manufacture
(folding and welding) was more controllable; tinadur had to be deep
drawn as it could not be welded.

I assume theat the eingines had seriel numbers or block numbers that
identified their peculiarities.

The Jumo 003C4 also entered production. It was delivered to the
factories (Messerschmitt, Gotha etc) and flown but it may not have
entered service.

This is the obiturary of Franz Anselm; it talks of the MTBO of the
Jumo 004
http://www.memagazine.org/backissues...anz/franz.html

"With hollow blades of Cromadur sheet metal, the complete 004B engine
contained less than 5 pounds of chromium. The first production model
of the 004B weighed 220 pounds less than the 004A. Additional
modifications were made to the first compressor stages. A series of
100-hour tests were completed on several engines, and time between
overhaul of 50 hours was achieveda"

It's clear the article refers to 004B4 engines with cromadur blades.



all the best -- Dan Ford
email: (put Cubdriver in subject line)

The Warbird's Forum www.warbirdforum.com
Expedition sailboat charters www.expeditionsail.com

"Keith Willshaw" wrote in message ...
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Cub Driver wrote in message
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Pete Stickney wrote in another thread:


These allied engines were so succesfull and powerfull that non of
them
could be installed on an aircraft. irony off


What propelled the Meteor then ?

Rubber bands ?

The Welland of the Meteor I could, admitedly, outperform a rubber band

The Meteor III improved the situation but was still no faster than a
top line piston fighter at altitude. (TA 152H, P51H, Spitefull, Do
335, P47M)


Meteor III was considered superior to the Tempest V in all depts
except for roll rate, the Meteor III's with long nacelles were faster
than the Me-262 and the Meteor IV's were capable of 580 mph

Keith


The Meteor was a well designed aircaft but it did require a lot more
thrust and development to actualy perform as a 'fast Jet' and clearly
the concept lived on in the Canberra bomber with its high speed and
high altitude but it was intrinsically a transonic aircraft.

Its also inplausible to assume that Messerschmitt would have been
siting on its hands with Me 262A1a fitted with 880kg thrust Jumo 004B1
while the British developed Meteor I, Meteor III, Meteor III long
nacelle etc.

The Jumo 004C increased thrust to 1000kg pushing the Me 262 top speed
to 578mph (its record level flight speed), while the Jumo 004D pushed
the thrust to 1050kg.

At that point the much lighter and much much smaller frontal area
BMW003D at 1100kg thrust might have been ready with its much better
fuel consumption and lower drag and latter still the Me 262 with
Heinkel Hirth HeS 011 with 1300 (hopefully raising to 1700kg)
turbojets installed in the armpit position. (the BMW003D was needed
for long range reconaisence versions of the Arado 234)

Trouble is by then theUSAAF would have been delivering a
special physics package to Berlin using a B-29 escorted by P-80's

Keith

That is certainly outside the scope of the discusion whcih relates to
the comparative merrits of Allied and German jet engines and aircraft.

Delivering a nuclear bomb to Berlin, in the circumstances that the war
had of been delayed due to for instance a delay in D-Day produced by
some kind of advance in jet engines (ie getting them into service 1
year earlier) or submarine warfare (getting the Type XXI subamrine in
service 1 year earlier) would have been far more difficult than
delivering one to japan.

The Germans always managed approximetly 1%-3% attrition against allied
aircraft by FLAK alone and sometimes against the RAAF much higher
(cities defended by 128mm cannon). On top of that German aircaft had
the performance to intercept B29s wheras the Japanese had not. The
477mph 50,000ft service ceiling TA 152H1 could get at a B29 without
difficulty (and it could out turn any allied aircraft to boot) as
could both the 458mph Fw 190 D12 or Me 460mph 109K4 or the Do 335 with
similar speed and long range standoff 30mm cannon. Then of course
there was the Me 163 rocket fighter which at 580mph while in a
20,000ft/minute climb could slash through even an early P80 escort and
of course the Me 262 possibly armed not only with R4M missiles but
standoff missiles such as the R100 or X4 guided missile. By that time
the Germans would have caught up in microwave techniques (they had the
FuG 244N3 microwave radar in production) as well and achieved a
substantial increase in FLAK accuracy.

So there was a substantial chance that an attempt to deliver a nuclear
bomb to Germany by say the end of 1945 or early 1946 would have been
shot down and that the bomb would fall into German hands.

It would have been a substantially riskier endeavour.

The Mig 15s swept the B29s from the sky over Korea.

The Jet was the end of the piston bomber.

There were only a small number of technical decisions that could have
gone either way that ensured a German defeat in 1945.

"Eunometic" wrote in message
om...


The Germans always managed approximetly 1%-3% attrition against allied
aircraft by FLAK alone and sometimes against the RAAF much higher
(cities defended by 128mm cannon). On top of that German aircaft had
the performance to intercept B29s wheras the Japanese had not.

A B-29 operating at night would have been nigh on impossible
to intercept. The only aircraft even remotely capable of
reaching it would have been one of the handful of Me-262
night fighters that were available. Of course by May 1945
the Luftwaffe was virtually nonexistent with most surviving
aircraft grounded by lack of fuel or pilots.

Flak was a risk of course but even the Flak 128 was pretty
much at the limit when dealing with the B-29

The Mig 15s swept the B29s from the sky over Korea

No sir they didnt. They inflicted losses to be sure but
B-29s detached from Twentieth Air Force continued flying
combat missions until the end of the war in 1953. After
October 1951 they flew their missions at night.

Keith