Jumo 213 vs. Napier Sabre

[J.A.W.]

There is supposed to have been a P & W engineer that got an R-2800 B series to around 3500hp for a few seconds on test stand using copious quantities of water/methanol, and well over 100in/hg pressure.
He may have been egging on the R-4360 engineers .
The engine survived. everybody knew it wasn't practical. Does sort of show the bottom end strength though.

Wilkinson just collected data/information sent to him. Maybe he did see a test run or two? but he did no independent testing.
Some of the data he has for French engines at times is a bit suspect, what he had for Japanese engines is almost laughable now and what he had for Soviet engine is no better than what you might expect at the time. By the way, I have twelve volumes of his work from 1941 to 1966/67.

That's why I'd like to see the Air Ministry 'Official Type Test' reports, since it would appear the Sabre data published in period by 'Flight', 'Janes',
& Wilkinson (much of which appears to be identical, figures-wise) would likely be derived from those reports, as a 'kosher' source.

 

[ThomasP]

re +20 lb boost

re
"What version of the Sabre had +20psi boost without ADI?"

and re
". . . if it is real, where is the power curve ?"

 

[J.A.W.]

re +20 lb boost

re
"What version of the Sabre had +20psi boost without ADI?"

and re
". . . if it is real, where is the power curve ?"

View attachment 759271

Yeah, Thomas, that chart would appear to pre-date the whole VA, VI, VII Sabre designation sequence, so would date from an earlier time,
when the E122 3,300hp variant was what the Napier Engine development team were pursuing.

re +20 lb boost

re
"What version of the Sabre had +20psi boost without ADI?"

and re
". . . if it is real, where is the power curve ?"

View attachment 759271

 

[ThomasP]

I believe it is from 1945.

 

[spicmart]

View attachment 720522

2564 HP @ 3700rpm, not perhaps mind-bendingly powerful for 1945.....until you see this is on 87 Octane "B4" fuel with water injection.
(Its pretty much 2200hp without the water.)

You can only do this with amazingly good water cooling system design to avoid any chamber hotspots.

(We can ignore the 2800hp pencil curve which is probably speculative.)

You once mentioned a 2900 HP figure gor the Jumo 213J.
Is it from this graph?

 

[J.A.W.]

I believe it is from 1945.

A bit odd, no mention of the Sabre VII? Or could that've been a late delineator for the ADI Sabre, vs dry, as Sabre VA?

 

[Deleted member 68059]

re +20 lb boost

re
"What version of the Sabre had +20psi boost without ADI?"

and re
". . . if it is real, where is the power curve ?"

View attachment 759271

The top curve is the E.122 which never existed as a physical engine.

 

[J.A.W.]

The top curve is the E.122 which never existed as a physical engine.

If we are to accept Fedden's considered view, no Jumo 213 with its 165mm stroke - running at 3,700rpm - could exist as a physical engine,
well, not long enough to fly, for any useful period of service, either.
Those piston ring lands would be pulverised - even if regular combustion could be maintained, with that 150mm bore - too.

 

[Deleted member 68059]

If we are to accept Fedden's considered view, no Jumo 213 with its 165mm stroke - running at 3,700rpm - could exist as a physical engine,
well, not long enough to fly, for any useful period of service, either.
Those piston ring lands would be pulverised - even if regular combustion could be maintained, with that 150mm bore - too.

This is all pure nonsense, for which there are no even concievable factual or engineering arguments given the complete
lack of any numbers provided. Its Fedden showing sour grapes that someone did something better than he did.

The 213 had massive efforts to make the pistons and rods lighter, F=ma

The stresses dont care what the speeds are, they dont understand them, the care about the weight of the parts
and the acceleration. Since the 213 parts were all made very light, the stresses are probably not even much higher
than in a Merlin.

 

[J.A.W.]

This is all pure nonsense, for which there are no even concievable factual or engineering arguments given the complete
lack of any numbers provided. Its Fedden showing sour grapes that someone did something better than he did.

The 213 had massive efforts to make the pistons and rods lighter, F=ma

The stresses dont care what the speeds are, they dont understand them, the care about the weight of the parts
and the acceleration. Since the 213 parts were all made very light, the stresses are probably not even much higher
than in a Merlin.

Well, the Merlin had a bad habit of its conrods failing (typical 'skimpy' R/R design) & took over a decade for crank end oil-feed,
something Napier (along with oil-jet to piston underside) had in their Lion, from 1918. (R/R Merlin racers tend to trust Allison conrods.

I do have a question you may be able to answer Calum; Do you know why, since Butch Harris was running a 'Merlins to Germany export
programme' for years (at the rate of hundreds a night, sometimes) why didn't the Germans re-use the valve & piston alloys from them,
to solve their own problems in that area?

 

[Deleted member 68059]

Well, the Merlin had a bad habit of its conrods failing (typical 'skimpy' R/R design) & took over a decade for crank end oil-feed,
something Napier (along with oil-jet to piston underside) had in their Lion, from 1918. (R/R Merlin racers tend to trust Allison conrods.

I do have a question you may be able to answer Calum; Do you know why, since Butch Harris was running a 'Merlins to Germany export
programme' for years (at the rate of hundreds a night, sometimes) why didn't the Germans re-use the valve & piston alloys from them,
to solve their own problems in that area?

They ran out of Nickel and after operation torch more or less ran out of Cobalt too.

Without those you cant make Merlin valves or Brightray/Stellite coatings even if you know what they`re made of. I would think
the Germans already knew perfectly well what to use, they just couldnt.

They got just about all their pistons from Mahle, who exclusively favoured very high silicon (i.e. low expansion) pistons over
our high copper alloys. This is a matter of some slightly subjective conjecture about what is best, I have discussed this
with two very senior F1 & ex: F1 piston metallurgists. There are pro`s and cons to both, and it is not definitively clear
which is best at high temperatures. It may be that the available test data does not show up the "slight" edge
the high copper alloys probably have at high temperature as they are not fatigue tests, the former head of
Cosworth tells me that the high copper alloy has the advantage over high silicon in terms of its properties
at high temperature under actual reversing load fatigue (which you wont see on a static test).

On the other hand the inverted V12`s probably had to use high silicon alloys beause you can of course
run a much lower piston to bore clearance when cold compared to high copper, which would have
been highly advantageous with the potential oil into chamber issues (oil in the chamber significantly
lowers the knock limit, right before you`re about to apply full boost for take off).

British reports tend to be derisive of the German high silicon alloys, but we almost exclusively used
high copper alloys, so it is fairly typical for that kind of attitude to develop.

In my opinion, the high copper probably has a very slight edge in high temperature mechanical strength
over the German silicon but it is not a large difference.

There are some erronious British reports which some people have picked up on where they noticed
that the DB 605 had suddenly put in pistons with thicker crowns, this was interpreted as "piston weaknes",
in fact this was done as a somewhat feeble attempt to prolong the life of the pistons when the Germans
were having their "detonation catastrphe" between 1941 and late 1942 due to the use of low Nickel
exhaust valves. The pistons were however not weak, the idea was to conduct a bit more heat out of the
piston through the skirts and thus alleviate a bit of the detonation by helping keep the piston crown a
little bit cooler.

This was eventually just about solved (to a degree, but always capped the allowable boost) by
very elaborate chrome plating of the valves instead of Stellite/Brightray coating and high nickel
base alloy for the valve itself.

 

[J.A.W.]

They ran out of Nickel and after operation torch more or less ran out of Cobalt too.

Without those you cant make Merlin valves or Brightray/Stellite coatings even if you know what they`re made of. I would think
the Germans already knew perfectly well what to use, they just couldnt.

They got just about all their pistons from Mahle, who exclusively favoured very high silicon (i.e. low expansion) pistons over
our high copper alloys. This is a matter of some slightly subjective conjecture about what is best, I have discussed this
with two very senior F1 & ex: F1 piston metallurgists. There are pro`s and cons to both, and it is not definitively clear
which is best at high temperatures. It may be that the available test data does not show up the "slight" edge
the high copper alloys probably have at high temperature as they are not fatigue tests, the former head of
Cosworth tells me that the high copper alloy has the advantage over high silicon in terms of its properties
at high temperature under actual reversing load fatigue (which you wont see on a static test).

On the other hand the inverted V12`s probably had to use high silicon alloys beause you can of course
run a much lower piston to bore clearance when cold compared to high copper, which would have
been highly advantageous with the potential oil into chamber issues (oil in the chamber significantly
lowers the knock limit, right before you`re about to apply full boost for take off).

British reports tend to be derisive of the German high silicon alloys, but we almost exclusively used
high copper alloys, so it is fairly typical for that kind of attitude to develop.

In my opinion, the high copper probably has a very slight edge in high temperature mechanical strength
over the German silicon but it is not a large difference.

There are some erronious British reports which some people have picked up on where they noticed
that the DB 605 had suddenly put in pistons with thicker crowns, this was interpreted as "piston weaknes",
in fact this was done as a somewhat feeble attempt to prolong the life of the pistons when the Germans
were having their "detonation catastrphe" between 1941 and late 1942 due to the use of low Nickel
exhaust valves. The pistons were however not weak, the idea was to conduct a bit more heat out of the
piston through the skirts and thus alleviate a bit of the detonation by helping keep the piston crown a
little bit cooler.

This was eventually just about solved (to a degree, but always capped the allowable boost) by
very elaborate chrome plating of the valves instead of Stellite/Brightray coating and high nickel
base alloy for the valve itself.

Ta for that Calum, very informative, however what I'd like to know is why the actual valves in situ from crashed Merlins
weren't re-melted (or machined to suitable size) for direct reuse in the German aero-engines?

My old classic Mercedes-Benz car has Na-filled exhaust valve stems so I'd presume that tech was de rigueur for all, then - too?

 

[Deleted member 68059]

Ta for that Calum, very informative, however what I'd like to know is why the actual valves in situ from crashed Merlins
weren't re-melted (or machined to suitable size) for direct reuse in the German aero-engines?

My old classic Mercedes-Benz car has Na-filled exhaust valve stems so I'd presume that tech was de rigueur for all, then - too?

It would be incredibly difficult to do that, the Merlin valves are usually coated with Brightray, which is basicaly 80% Nickel/20% Chromium
but the valve itself is a ferrous Nickel/steel alloy of different composition.

Additionally the exhauts valves are sodium filled, so you need to cut them up and drain them.

It would be a massive task to somehow reprocess those into usable base metals to construct more. In addition valve life
(even good valves) at the time was VERY low, mostly due to the horrendous acid attack from the leaded fuel
decomposition. So you need THOUSANDS of valves a month to make mass produced V12`s. You`d just never
economically be able to extract that amount of refined and cleaned alloy from crashes - even if the
entire RAF decided to park themselves in the ground in Germany one day.

 

[J.A.W.]

It would be incredibly difficult to do that, the Merlin valves are usually coated with Brightray, which is basicaly 80% Nickel/20% Chromium
but the valve itself is a ferrous Nickel/steel alloy of different composition.

Additionally the exhauts valves are sodium filled, so you need to cut them up and drain them.

It would be a massive task to somehow reprocess those into usable base metals to construct more. In addition valve life
(even good valves) at the time was VERY low, mostly due to the horrendous acid attack from the leaded fuel
decomposition. So you need THOUSANDS of valves a month to make mass produced V12`s. You`d just never
economically be able to extract that amount of refined and cleaned alloy from crashes - even if the
entire RAF decided to park themselves in the ground in Germany one day.

Well, between Berlin & Schweinfurt in late 1943, the USAAF & RAF were dropping those thousands of valves, plus interest...

Ironically, the mention of fuel-additive damage to valves, since that's one thing the sleeve-valves didn't encounter.

 

[J.A.W.]

Well, between Berlin & Schweinfurt in late 1943, the USAAF & RAF were dropping those thousands of valves, plus interest...

Ironically, with the mention of fuel-additive damage to valves, since that's one thing the sleeve-valves didn't encounter.

 

[J.A.W.]

Oops, what happened there? Ye gods, have I quoted myself, faux pas much!