BMW 801S: what were the power values?

[tomo pauk]

An interesting, to say at least, engine from Munich, the BMW 801S, was a high altitude version of the renown 801D-2. It was powering the Fw-190A-9, enabling it to halve the speed difference between the Fw-190A-8 and D-9. The A-9 was also a heavy weight, like the A-8.
My question is: at what full throttle altitude the engine produced what amount of power?
With or without the ram effect - anything goes. Preferably without overboosting (ie. at 1,4something ata); I'm interested at altitude values, since the take off power, with overboosting (SonderNotleistung) is stated at 2000 PS by many sources.

 

[DonL]

I wouldn't call it high altitude engine.

The BMW 801 S was an improved E.

Take off power 2000 PS, 1,62 ata; 2700RPM; C3 fuel (97 ROZ), emergency power was 2200 PS, best altitude performance 6050m with Ram; combat power 1500 PS at 2500 RPM.

The BMW 801 J was a high altitude engine, with Turbolader, take off power 1810 PS, 1,55 ata, 2700 RPM, C3 fuel (97 ROZ), best altitude performance 11500m, combat power 1500 PS at 2400 RPM.

 

[tomo pauk]

Thanks for the figures, DonL.

emergency power was 2200 PS, best altitude performance 6050m with Ram

Does that mean 2200 PS were available at 6050 m (so, second supercharger gear, with ram), just to make sure I'm reading it right? How big a manifold pressure was at that power setting?

 

[krieghund]

This is from Janes

 

[tomo pauk]

Great, many thanks

 

[Denniss]

2000/2200PS is a common error as it depicts the pure engine power. You have to subtract 70PS for the fan. Notice "Motorleistung" (pure engine power) and "Triebwerksleistung" (power arriving at prop).

 

[tomo pauk]

Great piece of information, it also replies to one of my questions on another thread

Looking at speed figures of the A-8, A-9 and D-9, along with power figures, those nicely indicate that the performance advantage of the D-9 vs. the A-8/-9 was simply a consequence of the clever (but too late) application of the in-line engine, ie. it's notably lower drag. The deletion of outer cannons helped, too.

Red line: 801S, yellow line: 801D (both Notlesitung) vs. the Jumo 213A.

 

[Denniss]

I wouldn't call it radial/drag vs inline, it was more a better supercharging and air intake system on the Jumo and no power loss from the strange fan. I don't know why BMW required this fan while almost no other similar engine (even higher powered ones) required one.
Another issue was 2-vale in the 801 vs 3 valve in the Jumo (DB used 4 valve since DB 600) so at higher rpm it was a little limited with power gains.

 

[tomo pauk]

The fan was necessary for cooling, at the end enabling it to have tighter cowling?
The power loss at high gear full throttle height and above was what, some 50 HP? The Jumo 213A did not have any special supercharger system, but a simple 1-stage, 2-speed*. Out of the 3 major things that determine engine's power (displacement, rpm and manifold pressure), the 213 had 2 (displacement, rpm). Not that it didn't have the MAP, it did, but the other 2 were engine's high points; the 2-stage variant were real beasts above 8 km.
I can agree the 801 have had an, say, unfortunate layout of the intakes - the air was entering intakes after being deisturbed by many parts of the engine itself. The full throttle height (at 645 km/h) was some 600 m higher vs. a static engine, not a major achievement (801D); so with ram effect it's providing those 1440 PS at 6300 m. The D-9 was gaining almost 1500 m, even if it's using the Steig Kampflesistung (speed 675 km/h); engine providing 1540 PS at 6600 m (with ram). Fairly comparable with P-51B/D gains through usage of ram effect.
The A-9's BMW-801S was providing 1700 PS at 6400 m (with ram), gain being modest 700 m. The 801 really needed those intakes from the Fw-190A-3/U-7...
Thanks for reminding me to that important 'ingredient' of the ww2 planes' performance. A small addition by yours truly: the faster the plane, the better harvesting of the ram effect. So the lower drag played part here too.

The line for the 801D in my post above is after the fan power is deduced; I'm not sure for the 801S. (help!)

*same with the 801C/D/S, among others

 

[Gixxerman]

Love these pics of these period radials.
How the hell did anyone mantain them under field conditions?
Amazing.