Fw-190 Prototype engine changes

[tomo pauk]

Was the Ju-211 series ever considered as a powerplant for the Wurger? For example the 1400HP version that powered the Ju-88A-4?

 

[Timppa]

Sure we're not looking at this from a race horse perspective?
Because regardless of who's right or wrong here, that's not where Kurt Tank was looking at it from.

The "cavalry horse" concept included a lot more than the engine. Ruggedness of the airframe, serviceability in field conditions, easy to fly qualities. All mentioned by Tank.

Whatever the designers preferences might have been, the RLM had the final say in what design could proceed and what could not. The DB601 option was rather academic anyway, as the production capacity was reserved for the fighters already in mass production, the Bf109 and the Bf110. That is not to say that Tank did not consider the BMW801 the best choice at the time, but it was also the only choice.

Even before the Fw190 entered service, the designers already studied alternative engines. The limited altitude performance of the BMW801 was acknowledged. This time they concluded that the DB603 would be the best choice, and prototypes were build. Eventually the RLM rejected the Fw190C, because the engines were needed for another Messerschmitt, the Me410.

Finally Fw used water cooled Jumo213 engines in their Fw190D/ Ta152 fighters (still "cavalry horses", IMO)

 

[davebender]

That cannot be right. The first BMW801 prototype was not running until April 1939. 1 1/2 year after the original RLM request that produced the Fw-190 fighter aircraft.

Does anyone know the production rate of the BMW139 radial engine during late 1937? I suspect it was not adequate to supply engines for the mass production Fw-190.

 

[tomo pauk]

....
Eventually the RLM rejected the Fw190C, because the engines were needed for another Messerschmitt, the Me410.

...

Yet another proof that Germans lost the war by themselves?

 

[Colin1]

Does anyone know the production rate of the BMW139 radial engine during late 1937? I suspect it was not adequate to supply engines for the mass production Fw-190.

As far as I know
there was no production rate in 1937, I believe there were about 9 units available but I'll need to check that when I get home

 

[Colin1]

1. The "cavalry horse" concept included a lot more than the engine. Ruggedness of the airframe, serviceability in field conditions, easy to fly qualities. All mentioned by Tank.

2. That is not to say that Tank did not consider the BMW801 the best choice at the time, but it was also the only choice.

3. Even before the Fw190 entered service, the designers already studied alternative engines. The limited altitude performance of the BMW801 was acknowledged. This time they concluded that the DB603 would be the best choice, and prototypes were build. Eventually the RLM rejected the Fw190C, because the engines were needed for another Messerschmitt, the Me410.

4. Finally Fw used water cooled Jumo213 engines in their Fw190D/ Ta152 fighters (still "cavalry horses", IMO)

Hi Timmpa
1. I'm not sure if you're agreeing with my views or disagreeing. I pretty much outlined everything that you mention in your first paragraph in my own submission; the cavalry horse concept was the whole bird, not just the engine.

2. That reinforces what I said about suitable powerplant candidates as rivals to the BMW 801.

3. Designers were indeed studying different engines, including the BMW 802 which would have featured 3-stage supercharging. The 801 was largely discounted for technical development bar one or two half-hearted or ill-advised programs to get more out of it.
Very largely, by the time they'd agreed on a suitable, higher-altitude engine for the Fw190, they'd also agreed (across the industry) that the piston engine had had its day, jet programs were being prioritised and programs like the BMW 802 were being scrapped.

4. Yes, it was the Jumo or no high-altitude, piston-engined performance for the Focke-wulf; the trade-off of powerplant ruggedness was a bargain considering the higher-altitude performance of the D models

 

[delcyros]

I am also not convinced that the BMW-801 was the best solution. As a matter of fact, the Fw-190 was designed around the 200 Kg lighter, albeit exactly as powerful BMW-139. The -801 worsened the estimated performance significantly.
The -801 is also quite late. The prototype was running well after the D-603 which also had advantages not only with a lower weight, less frontal area and less specific fuel consumption but also more initial poweroutput and a higher degree of reliability than the BMW-801.
In 1937, when design work on the future Fw-190 commenced, the Db-603 prototype engines were likely the most powerful in Germany, developing 1500 hp on the benchtest. The BMW-139 were projected for the same power but didn´t reached it until 1938 on the benchtest. The BMW-801 didn´t reach this until late 1940. To compare with the Db-603: In 1939, daimler benz reported that their prototype Db-603 established a short time record of 2800 hp and hope was expressed to reach 3500 hp!
So latest when the BMW-139 was abandoned, Focke Wulf and the RLM should have considered the inline Db-603 instead, which was ordered into production in 1940 (to begin in 1941 with true mass production in 1942). The Focke Wulf 190 would then become the next generation standart fighter for the Luftwaffe, without requiring the Bf-109 variants with Db-605. The 400-410 mp/h 109-F4 with Db-601E cleared for 1.42 ata still gives plenty of performance for the mid war period until fighter squads changed to the Fw-190 with Db-603.
In this way, the Focke Wulf would have replaced the Bf-109 in numbers from 1943 on, which also gives plenty of time to work out the bugs. Messerschmidt could then concentrate it´s efforts on the jet fighter.
Daimler Benz could bypass the Db-605 and turn out much larger numbers of Db-603.

the Fw-190V13 prototype with Db-603A was flying in july 1942, in our scenario it would have been flying in between 1940 and 1941. The prototype is basically what I want from a Bf-109 successor. It has no pressurized cabin and also lacks an exhoust driven turbocharger but its lighter and a high performance plane shining in between 3000m and 7000m altitude, without suffering the poor altitude performance common to the BMW-801 driven variants.

 

[davebender]

when the BMW-139 was abandoned, Focke Wulf and the RLM should have considered the inline Db-603 instead

BMW must have made huge promises concerning BMW801 engine performance. Otherwise I don't see why anyone would select it as a fighter engine over the DB603 or later versions of the DB601 / DB605.

 

[delcyros]

...add that BMW had real problems with reliability factors of this engine. The -A -B and -C submodels were never considered "operationally reliable" while the -D subvariant of the BMW-801 was reliable from 1943 on, not sooner than the db-603.

 

[KrazyKraut]

That is streching it. The BMW 801 was sufficiently reliable in 1942 to make the Fw 190 become the most feared German fighter over the Western front. The DB 603 wasn't ready until 1943. I don't know why BMW decided to discontinue the 139, but I am pretty sure they had a good reason to do so. If you design the Fw 190 for the DB 603 in the first place, you basically have the Fw 190 not ready until sometime in 1943. Great idea. The prototypes with the DB 603 were promising but the Jumo 213 was otherwise not used much so it was a logical compromise considering it wasn't that much worse. Not only did the Me 410 use the DB 603, it was also the choice for the He 219 and Do 335.

 

[Colin1]

The -801 is also quite late. The prototype was running well after the D-603 which also had advantages not only with a lower weight, less frontal area and less specific fuel consumption but also more initial poweroutput and a higher degree of reliability than the BMW-801.
In 1937, when design work on the future Fw-190 commenced, the Db-603 prototype engines were likely the most powerful in Germany, developing 1500 hp on the benchtest. The BMW-139 were projected for the same power but didn´t reached it until 1938 on the benchtest. The BMW-801 didn´t reach this until late 1940. To compare with the Db-603: In 1939, daimler benz reported that their prototype Db-603 established a short time record of 2800 hp and hope was expressed to reach 3500 hp!
So latest when the BMW-139 was abandoned, Focke Wulf and the RLM should have considered the inline Db-603 instead, which was ordered into production in 1940 (to begin in 1941 with true mass production in 1942). The Focke Wulf 190 would then become the next generation standart fighter for the Luftwaffe, without requiring the Bf-109 variants with Db-605. The 400-410 mp/h 109-F4 with Db-601E cleared for 1.42 ata still gives plenty of performance for the mid war period until fighter squads changed to the Fw-190 with Db-603.
In this way, the Focke Wulf would have replaced the Bf-109 in numbers from 1943 on, which also gives plenty of time to work out the bugs. Messerschmidt could then concentrate it´s efforts on the jet fighter.
Daimler Benz could bypass the Db-605 and turn out much larger numbers of Db-603.

the Fw-190V13 prototype with Db-603A was flying in july 1942, in our scenario it would have been flying in between 1940 and 1941. The prototype is basically what I want from a Bf-109 successor. It has no pressurized cabin and also lacks an exhoust driven turbocharger but its lighter and a high performance plane shining in between 3000m and 7000m altitude, without suffering the poor altitude performance common to the BMW-801 driven variants.

...I don't see why anyone would select it as a fighter engine over the DB603 or later versions of the DB601/DB605

All nice,
I'm sure that is what you want from a Bf109 successor but Tank's first reason for 801 selection

We chose an air-cooled radial for the new fighter for two reasons. Firstly, because such engines were far more rugged and could survive more punishment than the liquid-cooled types...

seems pretty unambiguous to me; he was obviously prepared to take the hit in performance for the hike in survivability - his cavalry horse.

 

[davebender]

Aren't those engine mounts identical? If so then a Fw-190D9 should theoretically be able to use either engine.

 

[delcyros]

That is streching it. The BMW 801 was sufficiently reliable in 1942 to make the Fw 190 become the most feared German fighter over the Western front. The DB 603 wasn't ready until 1943. I don't know why BMW decided to discontinue the 139, but I am pretty sure they had a good reason to do so. If you design the Fw 190 for the DB 603 in the first place, you basically have the Fw 190 not ready until sometime in 1943. Great idea. The prototypes with the DB 603 were promising but the Jumo 213 was otherwise not used much so it was a logical compromise considering it wasn't that much worse. Not only did the Me 410 use the DB 603, it was also the choice for the He 219 and Do 335.

The BMW-801 had an average service lifetime of 25 hours during 1941 and most of 1942 when the Fw-190A was deployed in the west. It was not operationally reliable by then (sic), as considered by the BMW-company and the RLM. That was the prime reason why the Fw-190 was only deployed in logistically and infrastructurally well developed areas and not on remote theatres of action by 1942. BMW was forced to derate the BMW-801D to 1.3ata in order to make it "operationally reliable" by late 1942 and this strongly points to problems with this engine until 1943.
The RLM would be very statisfied with a Db-603 driven Fw-190 ready in 1943.
Up to then, the Bf-109 can still hold it´s own.
Wrt engines, the db-605 doesn´t need to be put into large scale mass production. Free capcacities may shift to the Db-603. Ca. 1200 Me-410, ~400 He-219 and less than 800 Do-217/M/N/P with Db-603 were build.
That are 4.800 engines as opposed to 9000 Db-603 build. Even a modest increase in Db-603 production would allow a significant number of Fw-190 beeing build.

seems pretty unambiguous to me; he was obviously prepared to take the hit in performance for the hike in survivability - his cavalry horse.

That was not (and is not) a prooven theory. Tank wrote this long after ww2. Radial cooled engines are sensiblke to battledamage by other factors, notably the larger hitting area from typical firing arcs which kind of equalize vulnarability. I think Red Admiral posted figures which don´t show a significant statistical advantage of radial powered A/C once they got hit in the engine compared to liquid cooled ones.

 

[KrazyKraut]

All your objections benefit a lot from hindsight and I don't think the Luftwaffe pilots flying the early 190s would agree, or their RAF counterparts for that matter. By 1943 you'd have Spitfire MkVIIs and VIIIs available in some quantities, making any advantage of the Fw 190 rather slim if present at all. The 190 was available in the main theatre the 109 struggled at the time, France. In North Africa, Balkans, Russia the 109 was better or at least as good than the competition. The MTO is the exception, but I doubt that the 109 could've been replaced in more squadrons anyways since Fw barely produced enough airframes at the time to meet demands.

I see absolutely no valid reason why a 1939 airframe should be postponed to 1943 if it could be available a year and a half earlier.

I found a book (die grossen luftschlachten des 2ten weltkriegs) describing the view of the leading engineers Bruckmann and Sachse on the 139 (translation by me): They were never happy with the BMW139, it was an aging design. It was expensive to produce and had very little development potential, being essentially two P&W Hornets joined together. The BMW 801 could be fitted with very little modifications and immediatly solved the cockpit overheating issues and was more durable. Tank appreciated the move as, in his view, it would lead to a stronger aircraft, permit the installation of cowling guns the RLM was asking for and the engine featured fuel injection and the Kommandogeraet, which relieved the pilot of a lot of the engine control workload.

 

[delcyros]

The 190 was available in the main theatre the 109 struggled at the time, France. In North Africa, Balkans, Russia the 109 was better or at least as good than the competition. The MTO is the exception, but I doubt that the 109 could've been replaced in more squadrons anyways since Fw barely produced enough airframes at the time to meet demands.

I think it´s pretty safe to challenge this statement. The Bf-109F struggled over France? If so, then no less than the Fw-190. As a matter of fact, the RAF had a very negative fighter exchange ratio versus Bf-109F and Fw-190A over France and particularely vs Bf-109 over Malta and North Afrika in the 1941 to 1942 timeframe. I can only see an empirical but no statistical justification to make this claim. The Fw-190 impressed the RAF because it was something new. Had they been able to test a Bf-109F4 in good condition, they would have been more impressed wrt performances.
The soviets tested both and found the Fw-190A beeing less dangerous than the Bf-109F/G of this timeframe.

I see absolutely no valid reason why a 1939 airframe should be postponed to 1943 if it could be available a year and a half earlier.

The Fw-190A was not aviable in all theatres until 1943. It was only aviable, in limited quantities in well developed areas due to engine problems and nearly was cancelled by them. If You press the Db-603 instead of the BMW-801, You may get that plane this earlier, too (I don´t think that´s a good solution but both powerplants are somehow contemporaneous).
Kurt Tank considered the Db-603 as the best powerplant for the Fw-190 airframe.

They were never happy with the BMW139, it was an aging design. It was expensive to produce and had very little development potential, being essentially two P&W Hornets joined together. The BMW 801 could be fitted with very little modifications and immediatly solved the cockpit overheating issues and was more durable. Tank appreciated the move as, in his view, it would lead to a stronger aircraft, permit the installation of cowling guns the RLM was asking for and the engine featured fuel injection and the Kommandogeraet, which relieved the pilot of a lot of the engine control workload.

That´s an interesting contribution but I feel that Kurt Tank does need to justify the step because the original Fw-190 design was messed up with the BMW-801. In order to make a balanced comparison BMW-139 and BMW-801, one might need to stress some more points (the bmw-139, btw. was with fuel injection according to K.Gersdorf et al.) .

BMW-139 powered Fw-190V2:
-1550 hp take off power at 2700 rpm
-smaller wingarea with 14.9 m^2
-take off weight: 3125 Kg (with arms and radio)
-cockpit heating problems
-engine overheating problems
-wingload: 209,7 Kg/m^2
-powerload: 2.02 Kg/hp

BMW-801C powered Fw-190V5g (the base of the serial A0)
-1600 hp take off power
-wing area: 18.3m^2
-take off weight: 3400 Kg (with arms and raido)
-more durable, easy engine controll
-engine overheating problems
-wingload: 186 Kg/m^2
-powerload: 2.13 Kg/hp

The flying weight increased by nearly 300 Kg with new wings and the heavier BMW-801C! Altough the wingload was different between both versions, the power was not increased and this leads to less acceleration and little differences in turn performances.
More significantly are differences in speed between both planes.The V2 was faster than the V5g, owing to the 19% smaller wingarea and the larger propeller hub.
Now if You consider the DB-603 in 1939, which was more developed than the BMW-801 at this time, both, the V2 and V5g loose out to the Db-603. This powerplant was not considered until mid 1941 when construction of the V-13 commenced but it could have been under investigation as early as 1939, long before the Me-410 and He-219 were finalized with Db-603.

 

[davebender]

The original 1937 Fw-190 designs were powered by the DB601 engine. RLM requested a switch to the BMW139 engine during the summer of 1938. Why would they do that if the BMW139 was such a poor engine?

 

[delcyros]

I believe it was a logical step of the RLM. They wanted an airframe which could deal with the next class powerplants, which were believed to be in between 1500 and 1800 hp. These powerplants (BMW-801, BMW-802, BMW-139, Bramo 329, Db-603) were unsuitable to the Bf-109 in production, and likely impossible to fit in such a small airframe. The Db-601 production was also heavily loaded and couldn´t be expanded that easily. The Jumo-211 was neither as powerful nor as light as the Db-601 and the Jumo-213 was not under discussion.
It was probably believed that one of the radials would be the soonest operationally reliable powerplant of this class but to ignore the Db-603 is kind of ridicolous if You ask me. Fighters are no mule cars. They are racing horses and require a powerful but compact and as light as possible powerplant to get most performance.

 

[davebender]

Db-601 production was also heavily loaded and couldn´t be expanded that easily

Let's review the timeline.

1936 ?? month.
DB600 selected as the new Luftwaffe fighter engine. A new engine factory is constructed from scratch at Genshagen over a period of 10 months.

Feb 1937.
First DB600 engine completed.

June 1937.
The new factory has 5,813 workers.

Nov 1937.
65 x DB600 and 19 x DB601 engines produced.

It appears to me that building a DB601 engine factory from scratch and achieving mass production requires about 2 years. If the RLM orders another DB601 engine factory during the fall of 1937 it will be producing engines during the fall of 1939. Right on time to power the new He-100 / Fw-187 / Fw-190 (please select one or more aircraft). Meanwhile the BMW801 engine design is still in prototype and nowhere near production ready.

 

[Colin1]

That was not (and is not) a proven theory. Tank wrote this long after WW2. Radial-cooled engines are sensitive to battledamage by other factors, notably the larger hitting area from typical firing arcs which kind of equalize vulnerability. I think Red Admiral posted figures which don´t show a significant statistical advantage of radial powered a/c once they got hit in the engine compared to liquid-cooled ones

I didn't think any 'theory' existed concerning the relative merits of radial vs inline. I don't think saying that the radial engine could be hit by virtue of a larger hitting area reveals anything new; the fact is that liquid-cooled inlines couldn't afford to have their coolant lines perforated whereas radials could bring pilots home with entire cylinders shot away. This does not bestow any degree of invincibility on radials but in a very practical sense (rather than theoretical) radials could generally take more of a beating.

It was probably believed that one of the radials would be the soonest operationally reliable powerplant of this class but to ignore the Db-603 is kind of ridiculous if you ask me

Where is it documented that it was 'probably believed'? This sounds like speculation and as such, is a departure from documented fact.
The 801 wasn't riddled with problems, it overheated. At the time Otto Behrens and Karl Borris arrived from JG26 in March 1941 to assist in the testing, their one complaint was the overheating. They didn't fully resolve this until the 801D-2, when all the modifications from all the previous incarnations were brought together. It must have been annoying to both Focke-wulf and the RLM that they couldn't resolve this sooner but I don't think that was a reflection on the potential of the BMW-801 as a viable powerplant.
You argue a very good case for the DB603 which was undoubtedly a good engine but the documented evidence leans towards a pro-801 stance by the RLM. I think this is difficult to ignore, but...

Fighters are no mule cars. They are racing horses and require a powerful but compact and as light as possible powerplant to get most performance.

...as you are choosing to ignore the underlying tenet of Tank's design philosophy where the Fw190 was concerned, it is unsurprising that you seem to be ignoring that.
You've just described the Bf109/Spitfire formula that Tank didn't want another version of; to describe the 801-engined Fw190 as a 'mule car' is to deny air combat history of the RAF's biggest kick in the teeth during the entire war.

 

[KrazyKraut]

I think it´s pretty safe to challenge this statement. The Bf-109F struggled over France? If so, then no less than the Fw-190. As a matter of fact, the RAF had a very negative fighter exchange ratio versus Bf-109F and Fw-190A over France and particularely vs Bf-109 over Malta and North Afrika in the 1941 to 1942 timeframe. I can only see an empirical but no statistical justification to make this claim.

You seem to base most of your evaluation on raw performance data, something that is kind of typical to the forum. The main task of the fighter force on the western front (France) was defending against RAF attacks, combined fighter and bomber attacks. The 109F was, performance-wise, more or less evenly matched against the Spitfire but was somewhat underarmed and it showed as its single 15 or 20 mm cannon was not very successful against even twin engined bombers.

The Fw-190 impressed the RAF because it was something new. Had they been able to test a Bf-109F4 in good condition, they would have been more impressed wrt performances.

Speculation. They did evaluate the rather similar 109 G-2 and it didn't impress them as much as the Fw did.

The soviets tested both and found the Fw-190A beeing less dangerous than the Bf-109F/G of this timeframe.

Not to offend anyone, but when it comes to WW2 piston aircraft, when in doubt, I value the view of German, British or American testers a bit more than that of the Soviets.

The Fw-190A was not aviable in all theatres until 1943. It was only aviable, in limited quantities in well developed areas due to engine problems and nearly was cancelled by them.

Seriously. Acceptance of the Fw 190 was very good despite the initial problems. You make it look as if you could just develop the DB603 until 1943 and then bang have it available to all frontline units. Dream on.

If You press the Db-603 instead of the BMW-801, You may get that plane this earlier, too (I don´t think that´s a good solution but both powerplants are somehow contemporaneous).

Speculation. The DB603 was one of Daimlers high priority projects, so I think it was sufficiently pressed, maybe even more so than the BMW801. The 801 simply matured faster.

Kurt Tank considered the Db-603 as the best powerplant for the Fw-190 airframe.

Only after it became clear that you could not turn the 801 into a high altitude engine.

That´s an interesting contribution but I feel that Kurt Tank does need to justify the step because the original Fw-190 design was messed up with the BMW-801.

I feel you are speculating an aweful lot into what he said to prove your point. I rather take his words literally thank you. Besides that, Tank was never the one to make excuses. He always stuck with his preference of the DB 603 over the Jumo 213 and he always stuck with his statement that the Dora was but an interim solution. Doesn't sound like someone who makes excuses to me.

More significantly are differences in speed between both planes.The V2 was faster than the V5g, owing to the 19% smaller wingarea and the larger propeller hub.

Which only shows that the move to the 801 was very reasonable. Even in that configuration the wing loading was excessive. With the 139 you have no cowling guns and much less space in the wings for the increasing armaments. 4 MG 151 in the V2 wing? I doubt it.

Now if You consider the DB-603 in 1939, which was more developed than the BMW-801 at this time, both, the V2 and V5g loose out to the Db-603. This powerplant was not considered until mid 1941 when construction of the V-13 commenced but it could have been under investigation as early as 1939.

Could've been investigated? Yes. Would've been production ready earlier than 1943? No.