I don't understand how some planes ended up being so fast

[Shortround6]

The 2800hp R-2800 engine installation was far from trouble free in service at the 2800hp rating. Apparently the pressure inside the ducts (both exhaust and intake) was more than the duct work could really handle and the ducts needed constant attention (almost every time WEP was used?) to keep "air tight".
Little mention is made of the need to actually work on the engine and the basic power section was rated at 2400hp with water injection (56in MAP) using a single stage supercharger in commercial service by 1946.

Even more than the BMW 801 the "C" series R-2800 was ALL NEW, with no parts shared with the older engines.

Nobody else really got an air-cooled aircraft engine up to 1 hp per cubic in in the 1940s. A few may have made claims/advertised in the 1950s but I am not sure they actually panned out. For instance "Aircraft Engines of the World 1956" lists a Hercules 811 engine at 2250hp at 3,000ft wet but Lumsden doesn't list any 800 series engines. Likewise a Centaurus 373 is listed at 3220hp (3270 cu in) but Lumsden doesn't list any 300 series Centaurus engines.

 

[tomo pauk]

See my response to Deniss. The BMW801F(TH) was flown in the Fw 190V34 as early as Aug 1943.

The 801F can be regarded as analogous to the R-2800-57 which had a power rating of 1hp per cubic inch and was in essence completely engineered.

There was nothing wrong with the 801F, the Germans just couldn't set up production at that stage of the war, just a few of the more important components were transfered into the TS and TU

There seem to be a problem in nomenclature - the power-egg based on the BMW 801E engine was supposed to be called 801TH and TG (that one was with flame dampers), per 'Flugmotoren und Strahltriebwerke' by von Ghersdorff et al. Several chapters of that book are actually transcribbed in Russian language here, google translation is here. (with a grain of salt, some things will not add up due to 3 translations)
Most of the schematics are also taken from that book, the drawings of the BMW 800 line are interesting.

That book does list that 801E passed serveral 100 hr endurance runs at the test bench during July and Augus 1942, up to 2300 PS was achieved during the tests. Since the 801E required too much of chage in production tooling, it never went in mass production stage, some parts of it (heads, supercharger & inlet) were added to the 801D engine to create 801S.
The 801F was also to incorporate external, but streamlined intakes, new crankcase, valves, crankshaft with vibration dampers, increased S/C drive ratio, improver 'internal and external aerodynamics' - almost a new engine. BTW, the R-2800-57 was with turbo.
801F was discussed for the Ta-152, the engine was to be 'pushed' forward by 250mm to cancel out the CoG chages due to switch from the long V12 engine to the short radial. Power egg based on the 801F was to be called 801TF.

 

[Peter Gunn]

Also please note that the sleeve rises several inches above the the "head" surface. The ports, when closed are above the combustion chamber.

I don't think there are enough moving parts in this design...

Holy Cow! Did a watchmaker design this thing?

 

[BiffF15]

I don't think there are enough moving parts in this design...

Holy Cow! Did a watchmaker design this thing?

Concur!

Does anyone know if there are less moving parts to this set up than the "standard" valve layout? Also, it seems to have a weakness if hit in the "watch" mechanism it could take out the entire motor (sort of like liquid cooled engines and their ever so required liquid coolant).

Cheers,
Biff

 

[Koopernic]

Vernaleken/Handig in their massive Ju 388 book recall minutes from a meetings between Junkers and BMW on the BMW 801TJ-0 and the BMW801TJ-1. The meeting was held in 20 October 1944 where they anticipate production in January/February 1945 and they thought they could achieve a functioning installation at 2400hp with C3 fuel plus Water Injection and then achieve this in series engines with B4 Water Injection. It may have been ambitious but they were already at 2200hp.

The BMW engines within the 801TJ maintained their mechanical superchargers underneethn the turbo chargers.

Most of the problems uncovered during testing were pedestrian. Blocked or burst oil lines as a result of poor manufacturing, cracks in poor castings in the fan. New high altitude spark plugs from Siemens were required to resolve a problem that BMW was forced to admit had already occurred on the 801D2. Production problems meant they had to make do with a propeller that was inefficient due to tips going supersonic. They wanted a 6 bladed propeller.

2600hp was a special emergency power target of the 801F ie special (water injection).

The Simulations Junkers and BMW conducted indicated they could get 2400hp WEP for 15 minutes at sea level and 30 minutes at high altitude. There would be a marginal overstep of the cylinder temperature by 13C during climb at combat/military power also requiring MW50. They abandoned the ignition advance used in the 801TS and this helped keep the cylinders cooler.

So even though 2600 was not an immediate target 2400hp looked likely in a series engine even if it was the turbocharged version. By Feb 1945, the scheduled manufacturing date, Germany was split in two by the advancing enemies so it wasn't a situation conducive to logistics for a highly modified engine.

BMW's single seat fighter market for its radial was likely to disappear, the Jumo 213 and DB603 offered less drag, more power and had developed two stage superchargers and inter-coolers.

So if the 801E (within the 801TJ-1) could achieve 2400hp it so could the 801F and from 2400hp to 2600hp there is a smaller step. The 801TJ-1 never flew but it did run in an altitude test chamber and the slightly 701TJ-0 did fly

The bottleneck to increasing Jumo 213E power to 2500hp turned out to be the surprisingly low coolant flow of 9.5L/sec and too small radiators.

 

[pbehn]

I don't think there are enough moving parts in this design...

Holy Cow! Did a watchmaker design this thing?

The theory is that they are moving but not reciprocating like a valve against a spring, howver I would say the friction between the surfaces, even with oil lubrication probably means very little gain.

View: https://www.youtube.com/watch?v=lfS7XJZR2Ok

bristol photo centaurus engine - Google Search:

 

[tomo pauk]

Vernaleken/Handig in their massive Ju 388 book recall minutes from a meetings between Junkers and BMW on the BMW 801TJ-0 and the BMW801TJ-1. The meeting was held in 20 October 1944 where they anticipate production in January/February 1945 and they thought they could achieve a functioning installation at 2400hp with C3 fuel plus Water Injection and then achieve this in series engines with B4 Water Injection. It may have been ambitious but they were already at 2200hp.

The BMW engines within the 801TJ maintained their mechanical superchargers underneethn the turbo chargers.

US turboed engines engines also retained gear-driven superchargers.
The feature I like at German and Japanese turbo engines, admitedly there was just a small number produced of them, was that they also retained 2-speed gear change. That was a feature that enabled the 801J to acheive more than 1250 PS at 11800 m (rated altitude for 2nd gear; 1200 PS at 12000 m) at just 2400 rpm, while with just 1st speed engaged in the engine stage S/C it would've make just ~800 PS there. The BMW 801E-based turbo engine was supposed to make almost 1400 PS at 12000 m at 2500 rpm. Obviously, at 2700 both engines will make significantly more. Allied post-war data gives 1500 PS at 40000 ft for the 800(T)J.
Another feature is the use of hollow turbine blades, that saves plenty on size of fuselage, meaning also other 'knock-on' effects/benefits. The problem with all of this stuff is that it came too late to matter.
The 1st US service engine with hollow-bladed turbine was the R-1830 installed on the Curtiss SC Seahawk. Unfortunately, today there is no surviving aircraft of that type.

 

[Denniss]

801 TJ isn't an engine but a Triebwerksanlage with the turbocharged 801 J
the 801Q-2 in the Triebwerksanlage TU did no have a vastly improved supercharger but it may have achieved that power with C3 injection. It had a slight better take-off power than (early?) 801 D-2 (~20-30PS)
Most of the power ratings in the book are actually wrong due to the 1:1 PS/hp conversion
801 S power ratings are wrong because this is pure engine power without reduction for fan, 11/44 data from BMW has it at 2000/1930 PS with 1.65 ata.
The 11/44 BMW data has the 801F-1 at 2000/1940 PS with 1.65 ata
Both 801S/F were to achieve higher power ratings with more boost in 1945, the 801F probably with more rpm too. 801S was supposed to go to 2200PS (-fan)

 

[ChrisMcD]

The reason for the Bristol sleeve valve engines diameter being bigger than expected originally was that the Junk Head needed a lot of extra finning as power increased.
View attachment 473777

You can see the depth of the Junk Head from the above wikipedia picture. From the Junk Head sealing rings to the top of the fins is about the same as a normal push rod and poppet valve system from head gasket to rocker cover.

Roy Fedden really did try and do it the hard way with an air-cooled sleeve valve.

Whatever it's other faults the liquid-cooled Sabre did not have major cooling problems.

 

[ChrisMcD]

The 14N was a very light engine compared to other 14 cyl radials, the postwar Snecma R developments gained a lot of weight and got a little bit bigger in diameter.

According to Herschel Smith the 14M was the most compact, powerful radial ever made.

But I have a feeling that it was a bit too compact - it's war record was nothing special and it did not have a great reputation for reliability

 

[fastmongrel]

Roy Fedden really did try and do it the hard way with an air-cooled sleeve valve.

Whatever it's other faults the liquid-cooled Sabre did not have major cooling problems.

In the 1920s and 30s the sleeve valve looked to be the technology of the future to many experts. Problem for Fedden was the goalposts kept moving with things like Sodium cooled exhaust valves, anti friction coatings like Stellite, better spark plugs and oils eroding the theoretical advantage of the sleeve valve.

Bristols poppet valve engines were good, light and reliable but lacking in raw power. A 14 cylinder twin row radial with Mercury size cylinders might have been a cheaper quicker route to Hercules type power. A 18 cylinder twin row with Pegasus size cylinders could have been a good heavy bomber engine.

 

[fastmongrel]

According to Herschel Smith the 14M was the most compact, powerful radial ever made.

Powerful ? I dont think so unless you are comparing power to weight

Compact ? I think some of the Japanese radials of similar power made the GR engine look huge

 

[tomo pauk]

G&R 14M was light and small, 410 kg and 950 mm diameter. 14N was bigger brother - 590-630 kg, 1280 mm diameter.

Re. sleeve valve engines, the RR Eagle 46 (IIRC that meant 4 banks of 6 cylinders) was making 3500 HP from 2800 cu in, in service trim.

 

[KiwiBiggles]

G&R 14M was light and small, 410 kg and 950 mm diameter. 14N was bigger brother - 590-630 kg, 1280 mm diameter.

Re. sleeve valve engines, the RR Eagle 46 (IIRC that meant 4 banks of 6 cylinders) was making 3500 HP from 2800 cu in, in service trim.

RR Eagle = yet another copy of a Sabre.

 

[Zipper730]

Hope I got the right "quoter"!

You did

The obvious choice was the Napier Sabre, but it was considered too different in technology for anyone to be really keen.

The sleeve-valve reason was too different?

 

[Juha2]

... By Feb 1945, the scheduled manufacturing date, Germany was split in two by the advancing enemies so it wasn't a situation conducive to logistics for a highly modified engine....

In fact Germany wasn't split in two by advancing enemis by Feb. 1945, the Soviet operation from Oder began on 16 April 1945 and even the Western Allies attack from Rhein had begun not until 22 March. München area, where the main BMW factories lay was occupied in late April 1945.

 

[Zipper730]

Zipper, I love some of your posts, have you considered patenting the flying cube?

No, I don't think it'd fly too good.

I really have no idea what you are talking about here.

I was talking about power to weight ratios, and also structural strength to weight.

A good example would be the following

• An ant can lift 100 times its weight, and a flee can jump with the force of 50g (50 times its weight).: Nonetheless the amount of force the ant can lift is fairly little and the force a flee can produce during a jump is tiny compared to a human being.
• There was a female figure skater who was 92 pounds and could squat over 200; there was a power-clean record (male) that was around 2.7 times his weight. Either figures are much heavier than an ant or flee can produce, but are proportionately only 2.17 to 2.7 times their respective weights
• There are power-lifters who can lift more than the light human being, but it's a smaller proportion.

Understand?

I could be mistaken but Fuel fraction has very little to do performance except for range.

As a general rule that's right: However provided the following criteria are met

• At least two aircraft are involved, and for the sake of the argument: There will be two aircraft
• Both aircraft have the same armament: Say 4 x 20mm with 150 rpg
• Both aircraft have the same weight when armed, full fuel and oil: For some reason, I'll pick 10,000 pounds
• Both designs have the same wing-area (310 ft^2), same aspect ratio (6), same L/D ratio (13.5%)
• Both designs have the exact same horsepower engine (1875 hp) same critical altitude (24000 feet with ram)
• Design A has a fuel fraction of 11.1% (185 gallons) and Design-B has a fuel fraction of 16.68% (278 gallons)
• Both aircraft are stressed for a g-load of 9g ultimate when fully loaded at takeoff.

The following will be the case:

• Aircraft 1 & 2 will perform exactly the same when on 100% internal fuel
• Aircraft 2 will have a longer range providing the same basic cruise settings, and combat settings & limits will be used even if both use drop-tanks of the same size and capacity.
• Aircraft 1 & 2's performance will more radically diverge as fuel load goes from 100% to 80%, and from 80% to 50% as the different percentages of fuel will correspond to a different amount of fuel relative to the plane's weight: At 100% weight, Aircraft & 2 have no difference; at 80% weight, Aircraft 2 will weigh 98.85% the weight of Aircraft 1; at 50%, is 97% the weight of Aircraft 1.
• Aircraft 1 & 2's power-loading, maximum g-load capability, and corner velocities will all more radically diverge.

Please note that every plane built in the 1930s and early 40s had unused volume somewhere in the structure. The engines simply weren't powerful enough to allow all the "space" to be filled up.

Of course

The B-17 started as the Boeing 299 in 1934 and the first one used P & W Hornet (R-1690) engines rated at 750hp at 7000ft and 850-875hp for take-off. Empty weight was 21,657 pounds max loaded was 38,053 pounds. While they changed the rear fuselage/tail the wing stayed the same shape and area. The last of the B-17Gs weighed 32,720 pounds empty and 72,000 pounds maximum although even 65,000lbs called for restricted take-offs and very restricted maneuvers when flying. Obviously they filled up some of the empty volume over the years but trying to fly 65,000lb bombers with 800 hp engine wasn't going to get very far.

But horsepower went up considerably in that time...

See XB-15 or Boeing model 294 for what it took for a long range bomber with small engines. The Boeing 299/B-17 was Boeing's 2nd shot at a 4 engine bomber.

Honestly, I'm surprised they never thought of fitting the R-2600 to it.

 

[Koopernic]

801 TJ isn't an engine but a Triebwerksanlage with the turbocharged 801 J
the 801Q-2 in the Triebwerksanlage TU did no have a vastly improved supercharger but it may have achieved that power with C3 injection. It had a slight better take-off power than (early?) 801 D-2 (~20-30PS)
Most of the power ratings in the book are actually wrong due to the 1:1 PS/hp conversion
801 S power ratings are wrong because this is pure engine power without reduction for fan, 11/44 data from BMW has it at 2000/1930 PS with 1.65 ata.
The 11/44 BMW data has the 801F-1 at 2000/1940 PS with 1.65 ata
Both 801S/F were to achieve higher power ratings with more boost in 1945, the 801F probably with more rpm too. 801S was supposed to go to 2200PS (-fan)

Could you provide a "table" of core engine versus the "power egg" they were used on with a note on the nature of the engine as well as the sources you have used? This whole area is very confusing with a lot of contradictory data out theremand you seem to have sources.

Vernaleken & Handig clearly refer to the core engine within the BMW 801-TJ-1 as the 801E. It may be that 801J is a German Air Ministry designation.

I don't imagine that the book in its orginal German had a problem with the 1.6% error between Imperial and Continental Horse power.

The deduction of fan power is essential from the point of view of propellor calculations, however in comparison with other engines I don't think it needs to be accounted for because
1 Normal Propeller wastes power and thrust with blade area and cuffs of the roots being used to blow air on the engine as well.
2 The fan is producing some thrust. It doesn't just allow a more streamlined cowling, it is removing air from the front of the aircraft so that this air never has to pass over the air-frame. The air is then heated in the engine and likely ejected at higher velocity than it entered thus providing some modest thrust.
3 Its possible that at high speed the fan is wind milling rather than absorbing power.

Also what is the nature of the 801TU power egg, the power of 1730hp at 5700m (19000ft) that Smith and Creek quote is extremely good.

I had thought this might be a GM-1 rating. But this power level would be possible I think on a single stage supercharger. Air density at 5700m/19000ft is about 0.55 of sea level. If the 801D2 achieved 1710hp at 1.42 ata at sea level then the 801TU would need to achieve about 1.65 ata at 19000ft to provide 1730hp at the shaft since additional power (about 100kW) is required to drive the super charger and account for the slightly hotter air. This requires a pressure ratio of 3:1 and an ability to compress about 1000L of air per second.

 

[Denniss]

801A engine = 801MA (Motorenanlage)
801L engine = 801ML (Motorenanlage)
801D-2 or G-2 (not sure on this) = 801MG (Motorenanlage) = 801TC (Triebwerksanlage)
801TZ was also used for early/testbed Ju 188E, containing 801MA/ML engines
first 2 from 801 engine manual, latter two from Ju 188E Triebwersanlage

801Q = 801TU
801F = 801TH
801S = 801TS

the deduction for fan is always done by BMW and is the difference between Motorleistung (engine power) and Triebwerksleistung (shaft power, power delivered to prop)
data from BMW charts/graphs of 11/44 - may alo be available here in Technical section

The 801TU was supposed to replace the 801D-2 in the Fw 190A by ~7/44 and be equipped with erhöhte Notleistung system (1.58 ata at first SC gear, 1.65 ata in second gear). Fw 190 A-8 was ~30 kg heavier with TU engine due to oil system armor increase.

WWII Aircraft Performance has some additional docs with further confusing info, having both 801F/TH and 801F/TS.
It's possible the 801F project was split into smaller changes to become the 801S and larger changes to stay as 801F.

And yes, the Motoren-/Triebwerksanlage designations are confusing and terribly documented or docs not available/lost. Some designations of experimental engines may have been re-used, adding further confusion.
Ju 388 data points to 801J = TJ combination

 

[tomo pauk]

Pictures taken from the 'Motoren und Strahltriebwerke' book. The 801R was supposed to be outfitted with 2-stage, 4-speed S/C. The 801Q was, IMO, close sibling to the 801E. 801J is noted as 801D-2 with turbocharger.
The graph notes that 801E was to be core for the P. 8035 engine project. Please note the gear speed change at 8.5 km for the 801J, the turbo engine.
'Luftschraubenwelle + Luefter' = 'prop shaft + fan'.