Jumo 213 vs. Napier Sabre

[Engineman]

While it's clear that the turbine killed the large aero piston engine, if you're going to argue that sleeve valves are superior in some aspect you really have to explain why all the zillion motorcycle/auto/truck/locomotive/marine/industrial/etc/etc piston engines (including purebred racing engines where power/weight is certainly important) developed and produced after WWII all have used poppet valves (or piston porting for two stroke engines).

If you want to mention 2T engines and development, you have to recognise the enormous changes since WW2. Disc valves, Reed valves, porting and variable exhaust porting with exhaust chamber tuning. Piston porting was steady/reliable but limited. Modern 2T road engines can be 300bhp/litre and still flexible to use.

Eng

 

[yulzari]

While it's clear that the turbine killed the large aero piston engine, if you're going to argue that sleeve valves are superior in some aspect you really have to explain why all the zillion motorcycle/auto/truck/locomotive/marine/industrial/etc/etc piston engines (including purebred racing engines where power/weight is certainly important) developed and produced after WWII all have used poppet valves (or piston porting for two stroke engines).

One cannot mention two stroke aero engines without mentioning the Rolls Royce Crecy and, if sleeve valve engines had such sleeve difficulties, then why did Bristol, Rolls Royce and Napier continue to pursue sleeve valve engines?

Rolls-Royce Crecy - Wikipedia

en.wikipedia.org

 

[Shortround6]

The Hercules got pretty reliable eventually, but the trouble is even once you`ve got the sleeve metallurgy sorted (the tests took years and cost two million pounds,
which at the time would buy you 160 finished Spitfires)

I will note that in 1930 a geared P & W Hornet engine (R-1690) was advertised at $9,500 and a Wright Cyclone R-1750 (predecessor of the R-1820) was advertised at $10,000.
Granted both engines needed improvement (a lot to reach 1940 standards).

The sleeve valve solved a lot of the problems the poppet valve engines were having in the 1920s. Unfortunately for the sleeve valve, most of the poppet valve problems had been solved or substantially reduced during the 1930s.

 

[z42]

One cannot mention two stroke aero engines without mentioning the Rolls Royce Crecy and,

When I mentioned 2T engines, I was referring to earth-bound applications like chainsaws or outboard engines. Or at the other end of the scale, 2T marine diesels with uniflow scavenging. All successful and widely used. Which can't really be said about the Crecy.

if sleeve valve engines had such sleeve difficulties, then why did Bristol, Rolls Royce and Napier continue to pursue sleeve valve engines?

I think a lot can be explained by Harry Ricardo, a towering intellectual figure in engine research, being an early proponent of sleeve valves. And the stubbornness of Fedden, thinking that just a little more elbow grease will fix the issues after which the path to worldwide success is open.

Also note all this happened within the span of not very many years. Once a designer had committed to sleeve valves, backing out would require a major redesign of an engine, so by the time, say, Napier realized how troublesome the sleeves were going to be, it was too late to change direction.

 

[pbehn]

If you want to mention 2T engines and development, you have to recognise the enormous changes since WW2. Disc valves, Reed valves, porting and variable exhaust porting with exhaust chamber tuning. Piston porting was steady/reliable but limited. Modern 2T road engines can be 300bhp/litre and still flexible to use.

Eng

In a short space of time I rode motorcycles with all those types, Suzuki and Yamaha used different reed valve systems.

 

[cammerjeff]

I did some research on Sleeve Valves many years ago when I was involved in the restoration of a Knight Engine in a 1930 Willies Knight car. I found them very interesting, and as already stated they overcame alot of the early failure modes of 1900-1930's poppet valve engines. But they have quite a few downsides

(1) Expensive to build compared to a poppet valve engine
(2) more difficult to Machine (read more time and tighter tolerances required than were normal for the era, today with CNC machining it would not be a big issue)
(3) The Knight engine was much heavier than the Flat head I-6's of the era.
(4) When power was increased with more compression and RPM the heat generated tended to distort the sleeves.
(5) Higher than normal oil consumption due to the need to deliver oil between both the sleeves and the cylinder wall. This caused oil to be both burned when drawn into the cylinder during the intake cycle, and exit thru the exhaust port.

The benefits seen were

Smoother operation
and a much quieter engine than a Poppet valve engine of the day.

But I always find that an I6 engine in good condition is was of the smoothest engine designs there are, When we rebuilt and tuned the engine it always blew a bit of blue smoke out the exhaust, and a small amount of liquid oil would exit the tail pipe on start up after the engine had a few hundred miles on it.

But it did have a very unique sound to it, and I can see the appeal for its use in a Luxury car of the era.

Just my observations of a older automotive design, I have no experience with with the sleeve valve aircraft engines.

 

[Simon Thomas]

At 20,000 ft at max cruise, the Hercules 763 used in the HP Hermes IV has a BSFC of 0.482 lb/hp.hr while producing 1120 hp.
At the same operating condition, the Double Wasp CB17 as used in the DC-6B has a BSFC of 0.513 lb/hp.hr while producing 1090 hp.

Winding back the 763 to the same 1090 hp, the BSFC drops to 0.47 lb/hp.hr. That is 8% less fuel per hour. For an airline that is a massive difference in both cost and payload.

The Hercules weighed 2395 lb dry and the CB17 weighed 2390 lb dry.
The Hercules has an OD of ø52" and the CB17 has an OD of ø52.8" (Hercules has 3.1% less frontal area)

Ref Hercules 760 series MM and P&W Spec 8139, with CB17 operating limitations from the C118A and Everts OM.
No RAM effect for either engine. (This will change the BSFC for both engines, but the effect will be similar for both.)

 

[Shortround6]

I am not denying that the Hercules wound up a very, very good engine. It just took a while to get there.

Likewise the R-2800 went through a number of steps to get to the point of the CB17 engine and it's cousins, which only share the bore and stroke with the wartime C-2800s. I don't even think they use the same connecting rods and pistons with the "C" series engines in the P-47N.

Airline companies in the late 40s and the early 50s had to balance a lot of different factors. SPC at certain speeds/power levels was just one.
Cost of fuel was another. You don't buy 108/135 for the same price as 100/130 and you sure don't get 115-145 for the same price as the lower grades.
P & W was using water injection in just about everything short of the company pick up trucks.
Most early/mid 50s R-2800s could make 2200hp dry for take-off up to 3,000-6000 feet. Not all all airports are at sea level. Depending on model they could use 2400-2500hp at a lower altitudes using water injection.
The Hercules 763 could make 2080hp for take off and 2140hp at 3750ft.
The Hercules 773 could make 2125hp for take off and 2150hp at 1500ft using water methanol using lower (100/130 fuel).

The R-2800 engines could get a heavier aircraft off the ground thus carrying more payload or more fuel for longer range even if it used a bit more fuel at cruising speeds. A lot may depend on actual routes/payloads

All information in this post is from a 1954-55 Jane's and may differ from company figures or from figures given out at different dates.

Please note that the Hercules 100 series military engines and 600 series civil engines were limited to 1690hp for take off and the 200 series military and 759 and lower civil engines seem to rated at 1925-2040hp for take-off. They were several hundred pounds lighter (under 2,000lbs for the lower powered ones with single speed superchargers)

 

[BobB]

I am not denying that the Hercules wound up a very, very good engine. It just took a while to get there.

Likewise the R-2800 went through a number of steps to get to the point of the CB17 engine and it's cousins, which only share the bore and stroke with the wartime C-2800s. I don't even think they use the same connecting rods and pistons with the "C" series engines in the P-47N.

Airline companies in the late 40s and the early 50s had to balance a lot of different factors. SPC at certain speeds/power levels was just one.
Cost of fuel was another. You don't buy 108/135 for the same price as 100/130 and you sure don't get 115-145 for the same price as the lower grades.
P & W was using water injection in just about everything short of the company pick up trucks.
Most early/mid 50s R-2800s could make 2200hp dry for take-off up to 3,000-6000 feet. Not all all airports are at sea level. Depending on model they could use 2400-2500hp at a lower altitudes using water injection.
The Hercules 763 could make 2080hp for take off and 2140hp at 3750ft.
The Hercules 773 could make 2125hp for take off and 2150hp at 1500ft using water methanol using lower (100/130 fuel).

The R-2800 engines could get a heavier aircraft off the ground thus carrying more payload or more fuel for longer range even if it used a bit more fuel at cruising speeds. A lot may depend on actual routes/payloads

All information in this post is from a 1954-55 Jane's and may differ from company figures or from figures given out at different dates.

Please note that the Hercules 100 series military engines and 600 series civil engines were limited to 1690hp for take off and the 200 series military and 759 and lower civil engines seem to rated at 1925-2040hp for take-off. They were several hundred pounds lighter (under 2,000lbs for the lower powered ones with single speed superchargers)

FYI, some questions and answers on R-2800CB16 in Convair 440.

 

[machine shop tom]

Then polishing and porting the heads, adding hooker headers, a Holley double pumper and a Cherry Bomb exhaust.

Now you are talking MY language!

 

[Deleted member 68059]

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.)

 

[Shortround6]

FYI, some questions and answers on R-2800CB16 in Convair 440.

Thank you

 

[BiffF15]

FYI, some questions and answers on R-2800CB16 in Convair 440.

Looks like a set of Master Question File (MQF) list for pilots / flight engineer, typically used for training and or check rides.

 

[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:
Jumo-213J = 3700rpm
2900PS 2.02ata with MW50 using B4
2400PS 1.66ata no MW using B4
Would that have been still feasible/valid?

Can you give figures of other late-war high-power fighter engines which could have been reached when using B4?
And is it possible to estimate how high the Jumo 213J's performance could have been when using C3 (96 octane) or higher octane fuel?

So that one can have an imagination of how advanced this engine had been in comparison.

 

[Galahad]

FYI, some questions and answers on R-2800CB16 in Convair 440.

Sorry for maybe OT, but I'm a little bit confused about mentioned BHP figures of R-2800 C- and E-series. According to the above file a postwar CB 16 needs obviously only 59,5 inch (wet) for 2400 BHP - I think this is without RAM.


This document of a (wartime!) E-series 34W shows motor needs approx. 70 inch (combat = wet) to go for 2300 BHP (with RAM approx. 2800 BHP, but this don't matter):

The biggest impact on performance of ram that I ever saw is in F8F-1, F7F-3/1 and AU-1, the three use the same light weight low alt R2800.
An impact in the crit alt of 6000 feet at 420mph, this allows this aircrafts to have 2800HP at SL and 2350HP up to 12000 feet at high speed.
From AEL-999 Combat Power Endurance Test of Pratt & Whitney Model R-2800-34W Engine.
View attachment 675649View attachment 675650

More horsepower at lower MAP: is it plausible - or in other words, where's the mistake?

 

[ThomasP]

Hey Galahad,

The engine running 2300 BHP at 70"Hg is not using ADI. Note that there is no 'W' behind the 'R-2800-34' in the title block of the graph.

 

[Galahad]

Hey Galahad,

The engine running 2300 BHP at 70"Hg is not using ADI. Note that there is no 'W' behind the 'R-2800-34' in the title block of the graph.

View attachment 724289

You're right, I remember another report of R-2800-32W, they only did "dry" power runs.

As commonly known, if you equip a supercharged engine with water injection, you can generate higher boost pressure = more power.

Water usually is injected in the eye of impeller, respectively before supercharger. MAP is always measured on intake manifold respectively "before the valves", means behind supercharger. Thus, for maximum allowed boost pressure of an engine, it doesn't matter whether this is achieved with or without water.

Example: F8F-1 pilot's manual says, maximum allowed boost pressure of -34W engine is 65 inch (wet, and 115/145 fuel). As on AEL report can be seen, engine is capable doing 70 inch obviously even without water. The main purpose of water injection is to keep inner parts cooler and allow high power output for a certain period of time.

Again the question: hard to believe, why a C-series civilian CB-16 can do 2400 HP with only 59.5 inch
- and not to forget 100/130 fuel!
Maybe this is with RAM (but would be unusual figure for civilian use)?

 

[Metrallaroja]

Sorry for maybe OT, but I'm a little bit confused about mentioned BHP figures of R-2800 C- and E-series. According to the above file a postwar CB 16 needs obviously only 59,5 inch (wet) for 2400 BHP - I think this is without RAM.


This document of a (wartime!) E-series 34W shows motor needs approx. 70 inch (combat = wet) to go for 2300 BHP (with RAM approx. 2800 BHP, but this don't matter):



More horsepower at lower MAP: is it plausible - or in other words, where's the mistake?

Hi,
Ram effect increases MAP above the zero ram critical alt.
In this case, the R-2800-34 first stage 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.

Zero ram MAP:


420mph ram MAP:

Hey Galahad,

The engine running 2300 BHP at 70"Hg is not using ADI. Note that there is no 'W' behind the 'R-2800-34' in the title block of the graph.

View attachment 724289

That W is just a suffix that P&W uses to indicate that water injection is installed from factory, it does not have any other added value.
For example about R-2800-8:

Anyways, in this case it is probably just a typo. They are the same engines and all use water injection.

 

[Metrallaroja]

I remember another report of R-2800-32W, they only did "dry" power runs.

That is a calibration report.
Calibration reports dont include water injection runs.

Example: F8F-1 pilot's manual says, maximum allowed boost pressure of -34W engine is 65 inch (wet, and 115/145 fuel).

Power plant chart of the flight manual is more updated than the engine limits (see ''revised 10-25-49''). It is probably based on the AEL-999 report I posted and it indicates 70''.

As on AEL report can be seen, engine is capable doing 70 inch obviously even without water.

As stated above, the full report is about water injection.

Again the question: hard to believe, why a C-series civilian CB-16 can do 2400 HP with only 59.5 inch
- and not to forget 100/130 fuel!
Maybe this is with RAM (but would be unusual figure for civilian use)?

60'' for 2400hp is normal for low gear R-2800.

With 100/130 fuel, regular power low gear is about:
Military Power = 52'' 2100hp 2800rpm
Combat Power (wet) = 60'' 2400hp 2800rpm
Note: Water injection allows for higher power than 60'' even with 100/130, 60'' is just the regular setting but 65'' and even 70'' can be run on 100/130 with water injection

With 115/145 fuel, regular power low gear is about:
Military Power = 58'' 2300hp 2800rpm
Combat Power (wet) = 70'' 2800hp 2800rpm

 

[Galahad]

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?

btw: 420 mph RAM run at sea-level is only theoretical. No single engine R-2800 powered aircraft reaches that speed - so 2800 HP with a R-2800 is theoretical.