Focke-Wulf Fw 190/Ta 152 Performance Chronology

[CORSNING]

I am attempting to put together a quick reference performance timeline for the basic versions of the Focke-Wulf fighters. I am hoping that with the help of the members here a quick timeline reference sheet can be put together for comparisons of each Focke-Wulf version to its contemporaries.
I hope to put together the following information:
1. The basic versions; A-1, A-2, F-2, D-9, Ta 152H-0...etc. plus any sub-variants that had an increase in performance affect like the /R-4 with engine boosting system.
2. The date that the version listed became operational. If that date is not known, the date that it entered service (ES) will be listed if possible.
3. The first unit to use that version operationally.
4. The engine that version used and rated power levels.

I have very limited knowledge of the Focke-Wulf fighters and its engines. Biff15 and Shortround6 came up with the excellent Idea of breaking the versions down into smaller groups in order that I can keep up with the information flow from everyone as it comes in. With that in mind I will start off with the Fw 190A versions. Once enough information has been filled in, then I will add the fighter-bomber versions followed by the longnose versions.

This is what we have been able to put together so far:

Fw 190V1: First flight on June 1, 1939...BMW 139: 1,529 hp./Take-off.

Fw 190A-0: Delivered Aug.'41...II./JG.26...BMW 801C-0: 1,539 hp./Take-off. None saw combat because of engine overheating.

Fw 190A-1: 7 Aug. 1941.....II./JG.26.....BMW 801C-1: 1,539 hp.(1,560 PS)/T.O. S.L. 1,361 hp./15,100 ft. and 1,440 hp./S.L. for climbing.

Fw 190A-2: Mid-Dec.'41....II./JG.26....BMW 801C-2/1.32 ata: 1,539 hp.(1,560 PS)/T.O. S.L. 1,361 hp./15,100 ft. and 1,440 hp./S.L. for climbing.

Supercharger gears were changed from BMW 801C-2(B4 fuel):7.46:1 to BMW 801D-2(C3 fuel): 8.31:1

Fw 190A-3: March 1942.....II./JG.26...BMW 801D-2/1.42 ata?/2,400 rpm?/?????hp.

In October 1942 the BMW 801D was cleared for 1,42 ata./2,700 rpm: 1,677 hp.(1,700 PS)/T.O. S.L. 1,706 hp./1,968 ft. 1,420 hp./18,696 ft. and 1.32 ata/2,400 rpm.: 1,479 hp./S.L. climbing.

Fw 190A-4: July 1942....I./JG.1....BMW 801D-2

Fw 190A-5: January 1943....II./JG.2......BMW 801D-2

Fw 190A-6: June 1943.......I./JG.11....BMW 801D-2.

Fw 190A-7: December 1943.....Multiple Units.....BMW 801D-2.

Fw 190A-8: April 1944......Multiple Units......BMW 801D-2.

Fw 190A-8: July 1944: The BMW 801D-2 is equipped for emergency power boosting of 1.58/1.65 ata for 3 minutes without C3 injection.

Fw 190A-9: August 1944.....Stab II./JG.54...BMW 801 TS (C3 fuel)/????ata: 1,904 hp. (1,930 PS)/Take-off.

FIGHTER/BOMBER VERSIONS

Mid 1943 BMW cleared C3 injection for low blower (1st supercharger) and 1.65 ata. This was principally for the fighter-bomber versions.

January 20, 1944 BMW cleared C3 injection for high blower (2nd supercharger).

Fw 190F-1: ES: Mar.'44......Re-designated Fw 190A-4/U3.....BMW 801D-2

Fw 190F-2: ES: Oct.'43......Re-designated Fw 190A-5/U3......BMW 801D-2

Fw 190F-3: May 1943......Sch.G.1 Sch.G.2......BMW 801D-2

Focke-Wulf recorded that BMW had cleared C3 injection for use with the high blower gear as of
January 20, 1944.

Fw 190F-8: April 1944......III./SG.10......BMW 801D-2/C3 injection

Fw 190F-9: January 1945......Multiple Units......BMW 801 TS

Fw 190G-1: ES: Jan.'44......Re-designated Fw 190A-4/U8......BMW 801D-2

Fw 190G-2: ES: Oct.'43......Re-designated Fw 190A-5/U8......BMW 801D-2

Fw 190G-3: August 1943......II. III./S.K.G.10......BMW 801D-2

Fw 190G-8: April 1944......I./S.G.4......BMW 801D-2

LONGNOSE VERSIONS

Fw 190D-9: ES: Sep.'44......III./JG.54......Jumo 213A: 1,750PS(1,726 hp)/T.O.

Fw 190D-9: Oct.'44...... Junkers' Technical Field Service (TAM) Installed equipment kits: Jumo 213A: 1,750PS (1,726 hp)/T.O. and 30 minutes. Emergency Power: 1,900PS(1,874 hp) 0-16,400 ft.

Fw 190D-9: 14 October 1944...... III./JG.54.....68 A/C operational, 1 A/C equiped with Jumo 213A/MW 50: 1,750PS/T.O. and Emergency Power: 2,100PS (2,071 hp.)

Fw 190D-11: ES: Mar.'45 (13 standard A/C 4 A/C with EZ 42 gun sites are delivered)......Stab JG.300 II./JG.300 JV.44 (Protection Staffel)......Jumo 213F-1: 2,050PS (2,022 hp)/T.O.

Fw 190D-13: ES: Mar.'45 (2 delivered to units according to the aircraft distribution plans of Gen. Qu. 6 Abt.)......Unit?......Jumo 213F-1

Ta 152H-0: 1st delivery: 27 January 1945. 1st combat: 2 March 1945......III./JG.301......Jumo 213E: 1,750PS (1,726 hp).

Ta 152H-1: "It is not known whether later Ta 152H-1s with MW 50 or GM 1 power boosting were flown in action, and former pilots are also unable to confirm this." Deitmar Hermann's 'Focke-Wulf Ta 152', 1999.

Ta 152H-2: Aircraft allocation OKL/Gen. Qu. (6 Abt. IIIC): 2/04/45 one Ta 152H-2 to Luftflotta Reich.

Ta 152E-1:"It is known that work had begun in Erfurt..." "At least two Ta 152s left the production site in Erfurt-North." " On 15 April 1945 the Americans found two flyable Ta 152s there..." Page 50.

Ta 152C-1:"There is photographic evidence that production of the C-1 series was also begun by ATG in Leipzig." Page 50....DB 603E: ?????PS

Ta 152C-1: I have seen it written that this version may have been used in defense of its manufacturing facilities at the end of hostilities.

That is what we have been able to put together. Any corrections and/or additions are greatly appreciated.

Thank you all in advance for any contributions, Jeff

 

[Koopernic]

The BMW 801D-2 goes through several improvements that increase power starting at the end of 1943. The engine is however still designated as a BMW801D.
There is
1 The Application of "C3 einspritzung" which is the injection of C3 fuel (RON about 96/125 or 96/130) into the eye of the supercharger to precool the air as well as create a rich mixture. This technique was applied to ground attack variants. I don't believe increased manifold boost was used with this. This technique was initially restricted to use below 1500m but this was then released. It's purpose was to increase the speed of Fw 190F and G when hauling bombs as well as to help aircraft such as the Ju 188 get a load of the ground.

2 The Application of increased boost (higher manifold pressure) without C3 einspritzung though with likely use of rich mixtures, this was applied to the fighter variants, it was less powerful it seems but had other advantages.

3 The two techniques were effectively combined and in service around the first or second quarter of 1944. The Forsysth and Creek book has some chronology on it. I'll have a look at what they say.

There seem to have been some improvements on BMW801D2 supercharger hydrodynamics that improved altitude performance.

August 1944 sees the Fw 190A9 with the BMW801S engine in service. Usually it is refereed to as the 801TS. It initially lacks any kind of WEP such as the above but can sustain about the same power,2000hp, without it. Because the armored toroidal oil cooler is 10mm instead of 6mm it actually is 3 mph slower. Some kind of special WEP in the form of the Ribbentrop MW50 system may have been fitted at a latter date. The armoring was in part to provide for C of G changes that allowed fitting of a supplementary tank theoretically capable of flexibly carrying 25 gallons of MW50, extra fuel or cryogenic nitrous oxide.

What has happened is that BMW has been developing two advanced versions of their engine: the BMW801E and BMW801F; as advanced elements such as stronger pistons and vacuum caste precision heads became available they were applied to the BMW801D and used to produce an intermediate version, the BMW801S (or TS)

The use of the prefix M and T merely indicates the engine was supplied as a power egg (eg with the armored toroidal oil cooler) or with the propeller as well.

The use of the "T" in the turbocharged BMW801TJ has nothing to do with the word turbo. The J was the turbocharged version.

The evolution of the Fw 190D is just as complicated since its bomber engine based Jumo 213A had several modifications applied.

 

[Erich]

small incident but I. and II./JG 301 operated the Fw 190A-9 in September of 44 for their first missions in November of 44.

 

[CORSNING]

Koopernic,
Thank you for the information. I will be listing the F G versions next.

Erich,
Thank you for the information. There are no small incidents. Every bit of information is important.

Guys, where did you get your information?

Jeff

 

[tomo pauk]

Kudos, Jeff

...
Fw 190A-1: Sep.'41.....II./JG26.....BMW 801C-1: 1,578 hp./T.O. S.L. 1,361 hp./15,100 ft. and 1,440 hp./S.L. climbing.

Fw 190A-2: ES: Aug.'41....6./JG26....BMW 801C-2: Same as BMW 801C-1.

It is very much possible that main difference between BMW-801C-1 and C-2 was the allowance for the later to do full 2700 rpm in second S/C gear, vs. 2550; later the C-1 was also up-rated for that? The difference would be some 10-15 km/h above 15 km?
The data about 2700 rpm in 2nd gear can be found at Williams' site, the Fw-190A-2 article.

Supercharger gears were changed from BMW 801C-2:7.46:1 to BMW 801D-2: 8.31:1

Also the compression ratio was upped; gave a bit more power, but also made problematic real increase in boost (= real increase of power)? The C3 fuel was used on 801D, not sure whether the 801C went ever beyond B4.

Fw 190A-3: ES: Mar.'42...Operational Jun.'42?...II./JG26...BMW 801D-2/1,42 ata.: 1,706 hp./T.O. S.L. 1,420 hp./18,696 ft. and 1,479 hp./S.L. climbing.

The 2700 rpm 1.42 ata rating was allowed from October 1942 on, before that the limits were lower (for all power ratings).

Fw 190A-4: ES: Aug.'42....I./JG5....BMW 801D-2/MW-50: ????hp. or PS? First water-methanol injected production version.

Fw 190A-4/U1: Date?.....Unit?.......BMW 801C-2


Fw 190A-8: ES: Mar.'44...Operational May 31, '44?.....IV./JG3.......BMW 801D-2/MW-50: ???????hp. or PS.

The MW-50 was never used on BMW-801 operationally; I'd bow to a superior information, of course.
Fw-190A-4 was using 801D?


That is what I have been able to put together. Any corrections and/or additions are greatly appreciated.

Thank you all in advance for any contributions, Jeff[/QUOTE]

...

There seem to have been some improvements on BMW801D2 supercharger hydrodynamics that improved altitude performance.

The improvements of the S/C were applied from BMW 801S (or TS) engine.

 

[Denniss]

Take-off power of the 801C was 1560 PS, 801D-2 had 1700 PS, the often seen 1600 and 1730 are wrong because this is at ~800m and not at sea level. TO power of the 801S was 1930 PS - the often seen 2000 PS is pure engine power without deductions for the engine-driven cooling fan.
No C3 fuel used on 801A/L/C series, only in the D-2 and variants (Q-2, G-2) and the later versions E/F/S
The only difference between A-2 and A-3 was the engine.
The A-9 was not slower than the A-8.

The T designation is for Triebwerksanlage = complete replacement power-egg. From mounting framework in the back, exhaust system, engine covers to cooling fan in the front.
M = Motorenanlage = as T but no exhaust system and no mounting framework.

 

[CORSNING]

tomo and Denniss,

Thank you both for the excellent information. I have made the additions/corrections.

Jeff


Denniss,

In Deitmar Hermann's "Longnose" the graph on page 154 shows the speeds of the A-8 at 1.58/1.65 ata and A-9 at 1.65/1.82 ata. The only time the maximum speed of the A-8 is faster than the maximum speed of the A-9 is between the altitudes of 3,350-5,850 meters if both aircraft are using 1.65 ata. I believe that the 1.82 ata for the A-9 was approved in January 1945 but am not quite sure what the horse power/PS was at that level of boost. 2,367 hp. (2,400 PS)?

When was 1.58 ata boost cleared for the BMW 801D?

When was 1.65 ata boost cleared for the BMW 801D?

 

[tomo pauk]

Jeff, there is a fine amount of information re. BMW 801 in the William's site, Fw-190 section. Basically, overboosting from 1.42 ata to 1.58 was allowed in 1st S/C gear, while 1.62 (1.65?) was available in 2nd S/C gear. Trials were conducted on an Fw-190A-5, and the use is certainly documented for the Fw-190A-8.

 

[Andrew Arthy]

Hi,

Service entry of FW 190 variants:

A-1: II./J.G. 26, August 1941
A-2: II./J.G. 26, December 1941
A-3: II./J.G. 26, March 1942
A-4: II./J.G. 1, July 1942
A-5: II./J.G. 2, January 1943
A-6: I./J.G. 11, June 1943
A-7: various units, December 1943
A-8: various units, April 1944
A-9: Stab and II./J.G. 54, August 1944
D-9: III./J.G. 54, September 1944
F-3: Sch.G. 1 and Sch.G. 2, May 1943
F-8: III./S.G. 10, March 1944
F-9: various units, January 1945
G-3: II. and III./S.K.G. 10, August 1943
G-8: III./S.G. 1 I./S.G. 152, March 1944

Sources for above: pilot logbooks; Luftwaffe unit strength returns; Luftwaffe loss reports

For sub-variant entries into service, please see my website: Variants of the Focke-Wulf 190 / Ta 152 (but please bear in mind that I wrote that page ten years ago)

Cheers,
Andrew A.

 

[CORSNING]

Andrew,
Thank you for the information and the site. Does Rodeike happen to state in his book the date that each variant became operational?


PS: I have added the fighter-bomber versions and the Jumo 213 powered Fw 190s.

Any additions/corrections are greatly appreciated, Jeff.

 

[Andrew Arthy]

Hi Jeff,

In almost all cases the entry into service month was the same as the operational month. Here are the operational months/dates:

A-1: 7 August 1941 [source: Walter Schneider, Logbook]
A-2: mid-December 1941 [source: Walter Schneider, Logbook]
A-3: March 1942 [went straight into action upon delivery]
A-4: July 1942 [went straight into action upon delivery]
A-5: January 1943 [went straight into action upon delivery]
A-6: June 1943 [went straight into action upon delivery]
A-7: December 1943 [went straight into action upon delivery]
A-8: April 1944 [went straight into action upon delivery]
A-9: August 1944 [you note November 1944 in your list, but the first A-9s went directly to J.G. 54 in the Baltic States in August 1944, and straight into action against the Soviet offensive in that month]
D-9: 14 October 1944 [source: Hans Dortenmann, Logbook]
F-3: May 1943 [went straight into action upon delivery]
F-8: April 1944
F-9: January 1945 [went straight into action upon delivery]
G-3: August 1943 [were rushed to the Mediterranean theatre and straight into action against harbours in eastern Sicily in late-August 1943]
G-8: April 1944 [with I./S.G. 4 in the Mediterranean theatre]

Cheers,
Andrew A.

 

[CORSNING]

Excellent information Andrew. The quick reference sheet is looking real good thanks to all your excellent input.

Jeff

 

[CORSNING]

I have pretty much depleted my small knowledge of Focke-Wulf's fighters. If anyone has more information or sees corrections that need to be made, please do not hesitate to let me know.

Thank you all for all the help, Jeff

 

[CORSNING]

Duplicate post.

 

[Koopernic]

Take-off power of the 801C was 1560 PS, 801D-2 had 1700 PS, the often seen 1600 and 1730 are wrong because this is at ~800m and not at sea level. TO power of the 801S was 1930 PS - the often seen 2000 PS is pure engine power without deductions for the engine-driven cooling fan.
No C3 fuel used on 801A/L/C series, only in the D-2 and variants (Q-2, G-2) and the later versions E/F/S
The only difference between A-2 and A-3 was the engine.
The A-9 was not slower than the A-8.

The T designation is for Triebwerksanlage = complete replacement power-egg. From mounting framework in the back, exhaust system, engine covers to cooling fan in the front.
M = Motorenanlage = as T but no exhaust system and no mounting framework.

I don't accept this: TO power of the 801S was 1930 PS - the often seen 2000 PS is pure engine power without deductions for the engine-driven cooling fan.

The fan of the BMW801 was providing propulsive power as much as the propeller of any radial was. In the photographs below note that the BMW 801 gear driven high speed fan required a narrow opening. Not only did this allow a smaller tighter cowling it meant that all of the propeller was used to propel the aircraft, non of the propeller blade area near the shanks was over the engine itself. Note in the other photographs that R-2800 installations in P-47, F4U Corsair and B-26 that the bladed portion of the propeller near the shank is clearly driving air into the engine and not around the aircraft. Not so on the BMW 801 where all of the propeller is for propulsion and non for cooling. A substantial portion of propeller flow on the fanless R-2800 is diverted through the oil cooler (in the ventral scoop in the P-47, the wing scoops in the Corsair and the cowling scoops on the B-26). This is work done by the prop on instead of the fan.

The fan on the 801 is also creating suction (a proper aerodynamic term) and effectively providing a propulsive force. There is no need for cooling gills, the fan forces in the air, it is expanded by heating in the engine and then accelerated out of the exhaust system. No need for adjustable cooling gills to recover energy by accelerating the air. For purposes of engineering calculations of shaft power to the propeller deductions must be made but in terms of propulsive force the fan is as a propeller merely geared to a higher, optimal speed. The Fw 190 with the 2000hp BMW801 was very fast, faster than a Typhoon with the Sabre IIB engine running 150 octane. Had it a laminar wing or 150 fuel for 2400hp it might have matched the Tempest V as well.

 

[Denniss]

The deductions for the fan are a fact, based on BMW documents. If any there was just a little propulsion effect from the air pressed into the engine. The air is not pressed through the engine exhausts but through the side gills.

 

[Shortround6]

The fan of the BMW801 was providing propulsive power as much as the propeller of any radial was. In the photographs below note that the BMW 801 gear driven high speed fan required a narrow opening. Not only did this allow a smaller tighter cowling it meant that all of the propeller was used to propel the aircraft, non of the propeller blade area near the shanks was over the engine itself. Note in the other photographs that R-2800 installations in P-47, F4U Corsair and B-26 that the bladed portion of the propeller near the shank is clearly driving air into the engine and not around the aircraft. Not so on the BMW 801 where all of the propeller is for propulsion and non for cooling. A substantial portion of propeller flow on the fanless R-2800 is diverted through the oil cooler (in the ventral scoop in the P-47, the wing scoops in the Corsair and the cowling scoops on the B-26). This is work done by the prop on instead of the fan.

You have the same problem with air cooled engines as you do with liquid cooled engines. Air flow for cooling has to be maintained regardless of the forward speed of the aircraft and must be in proportion to the power being generated.

I am not sure how using power to drive a fan is so much better than using blade cuffs (on the P-47) or extending the airfoil section of the blade a bit closer to the hub (on the F4U). A number of planes with both cooling systems had trouble keeping the engine cool in ground running, taxiing and take off. Then you have climb, high power for several minutes at a relatively low airspeed. Roughly 1/2 of the airflow at high speed. then you have cruise, which could be 1/2 (or less for economy) the power needed for climb at a higher speed with more airflow. An engine that is too cold doesn't lubricate properly. No multi grade oil in WW II engines. Aircraft often using SAE 60 oil or equivalent. sometimes changed for weather conditions. As far as the substantial portion of airflow goes ? The prop disc area for a P-47 is around 116 sq ft, take out some of the center for your theory and the oil cooler is using up what. 2% of the disc area? Corsairs used and even bigger prop. 138 sq ft of disc area. area for the wings scoops is????

Doesn't matter how much power you have or how streamline the engine installation is if you cook the engine on the ground (Handley Page Hereford for one).

The fan on the 801 is also creating suction (a proper aerodynamic term) and effectively providing a propulsive force. There is no need for cooling gills, the fan forces in the air, it is expanded by heating in the engine and then accelerated out of the exhaust system. No need for adjustable cooling gills to recover energy by accelerating the air. For purposes of engineering calculations of shaft power to the propeller deductions must be made but in terms of propulsive force the fan is as a propeller merely geared to a higher, optimal speed. The Fw 190 with the 2000hp BMW801 was very fast, faster than a Typhoon with the Sabre IIB engine running 150 octane. Had it a laminar wing or 150 fuel for 2400hp it might have matched the Tempest V as well.

A lot of this doesn't pass the smell test. Think of a car with fan behind the radiator. Stopped or at low speed the fan creates a suction that pulls air through the radiator. However as vehicle speed increases the fans actual suction drops to nothing in effect because the speed of the air flowing through the radiator is higher (can be much higher) than the fan ever achieved on it's own. Clutch fans and now electric fans are used because the fan simply isn't needed at cruising speeds and simply uses power churning the air that has already served it's purpose (cooled the liquid in the radiator). Unless the fan in a FW 190 (or some of the fans used on R-2800 or R-2600s (some Martin Mariner flying boats) can actually accelerate air to several hundred miles per hour it has little, if any effect on propelling the the aircraft. Are the fan blades on the cooling fan adjustable in pitch? Propellers, in order to efficient at various speeds, altitudes and power settings are adjustable not only for RPM but for pitch matching blade angle of attack to the forward speed of the aircraft.

Now if somebody is really clever they may be able to set up a fan so that it gives the needed airflow awhile at warm up RPM while stationary on the ground and even gives proper airflow while doing 60-90mph down the runway at full power. and maybe the fan can actually restrict airflow at 300mph+ near sea level (3-5 times the airflow going into the cooling opening than at take-off) but trying to match the required airflow to the engine cooling needs gets a lot more complicated. Air is around 20% thinner just at 10,000ft so you need more cubic feet of it for the same cooling. Climbing at 180mph vs flat out at 360mph at 10,000ft? and so on.

 

[Koopernic]

You have the same problem with air cooled engines as you do with liquid cooled engines. Air flow for cooling has to be maintained regardless of the forward speed of the aircraft and must be in proportion to the power being generated.

I am not sure how using power to drive a fan is so much better than using blade cuffs (on the P-47) or extending the airfoil section of the blade a bit closer to the hub (on the F4U). A number of planes with both cooling systems had trouble keeping the engine cool in ground running, taxiing and take off. Then you have climb, high power for several minutes at a relatively low airspeed. Roughly 1/2 of the airflow at high speed. then you have cruise, which could be 1/2 (or less for economy) the power needed for climb at a higher speed with more airflow. An engine that is too cold doesn't lubricate properly. No multi grade oil in WW II engines. Aircraft often using SAE 60 oil or equivalent. sometimes changed for weather conditions. As far as the substantial portion of airflow goes ? The prop disc area for a P-47 is around 116 sq ft, take out some of the center for your theory and the oil cooler is using up what. 2% of the disc area? Corsairs used and even bigger prop. 138 sq ft of disc area. area for the wings scoops is????

Doesn't matter how much power you have or how streamline the engine installation is if you cook the engine on the ground (Handley Page Hereford for one).



A lot of this doesn't pass the smell test. Think of a car with fan behind the radiator. Stopped or at low speed the fan creates a suction that pulls air through the radiator. However as vehicle speed increases the fans actual suction drops to nothing in effect because the speed of the air flowing through the radiator is higher (can be much higher) than the fan ever achieved on it's own. Clutch fans and now electric fans are used because the fan simply isn't needed at cruising speeds and simply uses power churning the air that has already served it's purpose (cooled the liquid in the radiator). Unless the fan in a FW 190 (or some of the fans used on R-2800 or R-2600s (some Martin Mariner flying boats) can actually accelerate air to several hundred miles per hour it has little, if any effect on propelling the the aircraft. Are the fan blades on the cooling fan adjustable in pitch? Propellers, in order to efficient at various speeds, altitudes and power settings are adjustable not only for RPM but for pitch matching blade angle of attack to the forward speed of the aircraft.

Now if somebody is really clever they may be able to set up a fan so that it gives the needed airflow awhile at warm up RPM while stationary on the ground and even gives proper airflow while doing 60-90mph down the runway at full power. and maybe the fan can actually restrict airflow at 300mph+ near sea level (3-5 times the airflow going into the cooling opening than at take-off) but trying to match the required airflow to the engine cooling needs gets a lot more complicated. Air is around 20% thinner just at 10,000ft so you need more cubic feet of it for the same cooling. Climbing at 180mph vs flat out at 360mph at 10,000ft? and so on.

Shortround6, the cooling fan used on most (if not all) BMW801 installations clearly must have provided somewhat higher flow rates and pressure than possible over the low speed small blade area near the shanks of the propeller of a more conventional installation. Whereas a propeller shaft is typically geared down from main engine shaft speed the fan was geared up, about 3.17:1 v the propeller, thereby ensuring a high circumferential tip speed of the fan. One argument I have is that the 'fan' should simply be regarded as a second contra-rotating propeller or the fan on a turbofan geared to run faster as suits its smaller diameter. It's likely the flow rate versus pressure curve of the fan, which is also shrouded, that is more suited to forced cooling than a propeller

The blade area near the shanks of a conventional prop installation must have had a circumferential speed of about 65 mph and thus provided a not in substantial flow over the cylinder heads (above which they were placed). The oil cooler, which is radially further out on the B-26, Corsair, P-47 would have intercepted a much faster moving stream of air. An "air cooled engine" is really an oil cooled engine since around 50% of the heat is extracted from the oil cooler. The area dedicated to the oil cooler is substantial and so is the flow through it.

If you zoom into the picture of the BMW801D cooling flow that I provided you will notice that the oil cooler is quite large and integrated as a toroidal unit into the lip of the cowling ahead of the engine. The fan forces the air in a double reverse flow "S" shaped path through the oil cooler and ejects it in a narrow lipped collar behind the cowling, this lipped collar is so narrow most folks won't notice that it is there. BMW has succeeded in completely eliminating the frontal area taken up by the oil cooler, leaving the propeller completely free to provide thrust. There is no frontal area taken up by the oil cooler adding drag to the installation at all.


Another part of the flow is forced around the engine cylinders and heads and then is ejected in the exhaust gills on either side of the engine installation. I would hazard a guess that the flow rate versus pressure curve possible with a fan is more suited to this kind of work. Conventional installations rely on adjustable cooling gills to open up at low speed or high thermal load. Most useful is the fact that the fan is providing high cooling flow rates even at zero speed, something which is very important during take-off of a bomber: flaws in the cooling design of the early R-3350-21 were exposed during the take-off phase of the B-29.

The primary advantage apart from high cooling flow rates at zero forward speed is clearly the low drag and low frontal area installation. I would also argue that the gear driven fan is providing real effective thrust. The installation of a fanless radial clearly will have a high pressure area (dynamic pressure) generated at the fairly large intake area. The intake of the BMW 801 will likely have a suction that would reduce aerodynamic drag. The fan is directly forcing air though the engine, in the conventional radial it is dynamic pressure that forces it through and energy is removed from the air.

I would also argue that the fan is effectively providing thrust. I believe BMW 801D2 exhaust gas thrust at sea level was substantial: about 150kg, some of that would have been from the fan assuming it was measured on an instrumented stand.

For me all of this is about arguing that 80hp should not be deducted from the BMW 801 power when comparing to other radial engines anymore than power should be deducted for that portion of propeller airflow that is intercepted by the oil coolers, cylinder heads of conventional installations.

I would add that forced fan cooling was used by the R-4360, particularly the pusher versions.

I would question as to whether the fan of the 801 was using power at say 330mph (150m/sec) at sea level or 420mph (190m/sec) at 20000ft (50% pressure).

If the fan is providing suction it is doing useful work, it is not than it is not absorbing power from the engine apart from mechanical losses in the gearing.

 

[tomo pauk]

Stumbled on this: part of the data sheet covering Fw-190A-1 to A-4. The max speed should be with BMW 801D engine (ie. either Fw 190A-3 or A-4), without the outer wing guns, as it is here.
We can recall that the manual for the Fw 190A-5/A-6 gives a bit greater speed than the tests (4-9 km/h slower), so a grain of salt can be used also here.
(my translation)