Jumo 213 vs. Napier Sabre

[Metrallaroja]

Please, mate, need little bit more explanation

On these two graphs I only see:
- zero RAM: two runs (different engines), with 70 and 70.5 inch (high gear: 2300 HP at critical altitude 6000 ft)
- so-called "420 mph" RAM runs: with 70.1 and 70.3 inch (high gear: 2350 HP at - thanks to RAM - critical altitude approx. 11000 ft)

Where's something written about the figure 59.5 or 60 inch?

Are the low gear full throttle runs (2350 HP without, and 2800 HP with RAM) not also at approx. 70 inch - if not, why so?

As I said:

Ram effect increases MAP above the zero ram critical alt.
In this case, the R-2800-34 low gear has the zero ram critical alt for 70'' 2800HP below SL, so it needs ram to get to 70''.
At zero ram it only gets to 59.5'' that is why it produces 2350HP with zero ram.
Ram increases the MAP to 70'' and so the engine power increases to about 2800hp.

I joined power and MAP of both zero ram and 420mph ram for you:
As you can see in low gear zero ram, supercharger can only get to 59.5'' so it only produces 2350BHP. With a 420mph speed, ram effect increases the MAP to 70'' so power increases to 2800BHP
The high gear supercharger can produce 70'' with zero ram but the critical alt is 6000 feet, with a 420mph speed ram effect increases the crit alt to 12000 feet.

 

[Galahad]

Hmm, what did you mix?

The upper parts in your scans are the 70-inch full throttle dynometer runs.
Below looks like other charts from another run...

Would be nice to see full AEL report

 

[Metrallaroja]

Hmm, what did you mix?

The images I already sent.

Zero ram power:
View attachment 675649
Zero ram MAP:
View attachment 724318
420mph ram power:
View attachment 675650
420mph ram MAP:
View attachment 724319

 

[Metrallaroja]

The upper parts in your scans are the 70-inch full throttle dynometer runs.
Below looks like other charts from another run...

They are the same runs, look at ''plate numbers'' and the description below

Plate numbers:

Description:

You can find the plate numbers on the bottom right corner:

 

[Galahad]

They are the same runs, look at ''plate numbers'' and the description below

You can find the plate numbers on the bottom right corner:
View attachment 724456

Great!
Is it possible to show "plate 2, 3 and 6" as .jpeg or .png files? (better for me)

 

[Metrallaroja]

Great!
Is it possible to show "plate 2, 3 and 6" as .jpeg or .png files? (better for me)

2 is the 420mph MAP already posted View attachment 724319

I dont have the 6 but it would be the equivalent of the plate 3:

 

[Simon Thomas]

I think CAT is carb air temperature and CAP is carb air pressure, but ASRP has me stumped. Must be some form of manifold pressure. Can anyone decipher it?

 

[ThomasP]

I remember seeing the acronym ASR meaning 'Alcohol Substitution Ratio' in reference to mixing fuels/controlling the alcohol:diesel ratio while an engine is running, but I do not know how it is being applied in this case.

Maybe the 'MFR"S ASRP FITTING' is a device for regulating the flow of the ADI fluid based on manifold pressure settings?

EDIT The device we used had knock sensors incorporated to control the spark timing for different levels of alcohol in the fuel. It was easier and quicker to do the mixing while the engine was running than to prepare specific batches of fuel and then run each batch separately.

 

[Shortround6]

Some of the postwar commercial engines were rated on 100/130 fuel wet and for 108/135 or 115/145 fuel dry.
It sometimes depended on what they could get at certain airports.
Since the only time the civilian aircraft used the high boost settings was for take-off the time was short.
Perhaps there was a difference to high speed cruise with the better fuel but the take-off power was directly related to the allowable take-off weight and runway length.
Having to leave several thousands pounds of cargo or passengers on the ground cut into profits on shorter flights. Being able to lift enough fuel to actually make the flight was important on the long range flights.

Using water injection did substantially alter the fuel flow from the fuel system.

 

[Metrallaroja]

I think CAT is carb air temperature and CAP is carb air pressure, but ASRP has me stumped. Must be some form of manifold pressure. Can anyone decipher it?

"Absolute Supercharger Rim Pressure"

 

[Simon Thomas]

Thank you. That was driving me crazy all afternoon.

 

[ThomasP]

What the heck is "Absolute Supercharger Rim Pressure"?


DOH! Nevermind, I found the terminology in NACA Technical Report No.804, ie Absolute Supercharger Rim Pressure is the:

"intake-manifold pressure measured at supercharger-case rim, inches mercury absolute"

"Pressure at the supercharger-case rim was used in preference to the intake-manifold pressure because the pressure from only one intake manifold was available. It was thought that the pressure at the supercharger-case would probably give a better indication of the total air flow than the pressure at the one known cylinder."

 

[Simon Thomas]

Getting back to the Napier Sabre producing 5000 hp.

In the Aeronautical Journal volume 79, Issue 777, September 1975 there is a review of the book "Some Unusual Engines" by Setright. The reviewer is Air Commodore F.R. Banks, and he states this about the Sabre:

"Further, the Sabre never achieved 5500 bhp. The maximum (quoted by the reviewer [Banks] in his James Clayton lecture of 1951) was 3000 bhp on 100/130 grade fuel plus water/methanol injection."​

Ricardo in "The High-Speed Combustion Engine" Fourth Edition states:

"It gave a take-off and combat power of no less than 3050 B.H.P. when running at 3850 r.p.m. and had shown itself capable of a sustained output of 3600 H.P."​

I suggest that:

• 5000/5500 hp is a myth dispelled by a very well respected figure in Aircraft engines
• 3600 hp could be squeezed out in the Napier test bay during a long term test but with plenty of cooling water. I would consider Ricardo a dependable source.
• 3050 hp with ADI is the real maximum figure. I expect there is a type test somewhere to verify this, although I have never seen it.

I have attached Banks James Clayton lecture. It doesn't say much that we don't know.

 

[Deleted member 68059]

Getting back to the Napier Sabre producing 5000 hp.

In the Aeronautical Journal volume 79, Issue 777, September 1975 there is a review of the book "Some Unusual Engines" by Setright. The reviewer is Air Commodore F.R. Banks, and he states this about the Sabre:

"Further, the Sabre never achieved 5500 bhp. The maximum (quoted by the reviewer [Banks] in his James Clayton lecture of 1951) was 3000 bhp on 100/130 grade fuel plus water/methanol injection."​

Ricardo in "The High-Speed Combustion Engine" Fourth Edition states:

"It gave a take-off and combat power of no less than 3050 B.H.P. when running at 3850 r.p.m. and had shown itself capable of a sustained output of 3600 H.P."​

I suggest that:

• 5000/5500 hp is a myth dispelled by a very well respected figure in Aircraft engines
• 3600 hp could be squeezed out in the Napier test bay during a long term test but with plenty of cooling water. I would consider Ricardo a dependable source.
• 3050 hp with ADI is the real maximum figure. I expect there is a type test somewhere to verify this, although I have never seen it.

I have attached Banks James Clayton lecture. It doesn't say much that we don't know.

I`ve read a very large portion of the Napier company archive papers, and I`ve never seen a Sabre test curve above 3050 hp (NS.96 SM 3850rpm, takeoff power
with water methanol injection, thats at 17.25 lbs boost)

I think all the spurious figures are from the E.122 (Sabre VIII) which are all "projected" figures and the engine, as far as I`m aware
never existed in any real form, or certainly was never actually assembled and tested.

This is from the official Napier report on the history of the Sabre, published in 1947 (internally). This was type tested it says, (the 3055hp), so its
of course possible that somewhere a "sprint" dynamometer curve exists at a higher level. But I`ve not seen it if it exists.

3055 hp DEFINETLY represents the maximum which was ever type-tested.

There IS a single type written page showing the E.122, at 3350hp at 3750rpm. But I would note that this line has been hand written in, and so
could be anything (its the only line on the whole page which has been done by hand, which goes back to 1938). I think this was the
"expected" result of a test which never happened (or never reached the target and was quietly shelved) because it is not noted in the
official Sabre history essay (above) which was published in 1947, the year after this "test" below.

 

[Mike Williams]

View attachment 726710

Interesting. "... in 1945 the series VA ... gave a maximum output of 2,600 B.H.P." Anyone have anything more on 2,600 bhp with the Sabre II? Given that the Sabre II gave ~2,420 b.h.p. at 3,850 r.p.m. and 11 lb, what boost would give 2,600 B.H.P.? +13 maybe?

 

[wuzak]

By 1941 the series II, with its maximum output of 2090 B.H.P., had overcome most of the teething troubles and this engine was chosen to power the Hawker Typhoon, then Britain's leading fighter aircraft.

Certainly the Typhoon was, at that time, Britain's newest fighter, but was there a time where it was considered the leading fighter?

 

[wuzak]

Interesting. "... in 1945 the series VA ... gave a maximum output of 2,600 B.H.P." Anyone have anything more on 2,600 bhp with the Sabre II? Given that the Sabre II gave ~2,420 b.h.p. at 3,850 r.p.m. and 11 lb, what boost would give 2,600 B.H.P.? +13 maybe?

The Standard Data Pages for Reciprocating Engines for the Napier Sabre has the VA has 2,300hp @ 3,850rpm, +12psi for take-off, 2,600hp @ 2,500ft, 3,800rpm, +15psi boost in low gear, and 2,300hp @ 12,750ft, 3850rpm, +15psi boost in high gear.

This is from http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Napier_Sabre.pdf

 

[Admiral Beez]

Sabre was a terrible engine, the RAF was very glad to be rid of the relentlessly troublesome creature

It was poorly made until outside help from IIRC Bristol was brought it. Though it's noteworthy that none fly today when hundreds of Merlins fly on.

 

[Shortround6]

Though it's noteworthy that none fly today when hundreds of Merlins fly on.

That may due to the numbers involved and size/complexity of the engine.

Most sources say around 5000 engines were built vs the well over 100,000 Merlins.
The Sabres were phased out fairly quickly after WW II while Merlins were in low scale production well into the 50s? Support for Merlin powered aircraft continued for quite some time.
For a private owner (or Museum) maintaining a Sabre in flyable condition would be daunting. The whole 24 cylinder vs even 18 cylinders (spark plugs) and spare parts.
For a flyable plane you need some sort of certified mechanics, overhaul shop. and even under experimental rules you have to insure the thing.
Not saying it cannot be done, just saying it is a lot more difficult than keeping many other Warbird engines flying.

 

[Mike Williams]

The Standard Data Pages for Reciprocating Engines for the Napier Sabre has the VA has 2,300hp @ 3,850rpm, +12psi for take-off, 2,600hp @ 2,500ft, 3,800rpm, +15psi boost in low gear, and 2,300hp @ 12,750ft, 3850rpm, +15psi boost in high gear.

This is from http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Napier_Sabre.pdf

Thank you