Fw 190: the good, the bad and the ugly

[GregP]

While everything you said is true, Tomo, there wasn't much development left in the Fw 190 airframe.

Since it was right near the top of the fastest piston fighters ever made, it wasn't going to get much faster no matter what they did ... unless you think there was some unexplored aerodynamic advantage that nobody else ever thought of lurking on the horizon.

It was a damned good airplane that came at a time when it could do no good as the war was well and truly lost by the time the very first Ta 152 service sortie took place. The only reason it didn't see decent-scale service is that all use of the Ta 152 stopped with the end of the war except for test flights of captured examples. Except for that it might have been a very good service aircraft.

 

[Koopernic]

While everything you said is true, Tomo, there wasn't much development left in the Fw 190 airframe.

Since it was right near the top of the fastest piston fighters ever made, it wasn't going to get much faster no matter what they did ... unless you think there was some unexplored aerodynamic advantage that nobody else ever thought of lurking on the horizon.

It was a damned good airplane that came at a time when it could do no good as the war was well and truly lost by the time the very first Ta 152 service sortie took place. The only reason it didn't see decent-scale service is that all use of the Ta 152 stopped with the end of the war except for test flights of captured examples. Except for that it might have been a very good service aircraft.

Theoretically they could try a Laminar Flow profile wing but I think it would be too radical an effort as increases in wing planform and spar position might be required, the NACA 5 digit series was pretty good in any case and the chances of completing this transformation before a new generation of jets reached service were slim to none. I suspect an effort in maintaining airframe tolerances might have helped a great deal more. At a certain point it seems that engine power is more important than the slightly higher critical mach number.

As laminar flow wings can be thicker for the same critical mach the effort might have been justified if the change to a laminar profile wing meant that it could be made of wood, steel, plastic. Of course by the end of 1944 the RLM/Luftwaffe is trying to back peddle from any piston aircraft development it can to an all jet airforce and I think they would have sorted out their jet problems before any radical new piston aircraft could be introduced.



If one searches in detail one finds that just about every second version of the Fw 190 that was released had a small increase in wing area, usually about 0.6 sqm or so. The final version, the Fw 190A10 was to receive another wing area increase as well as an BMW801F engine good for up to 2400hp (2600hp with MW50). I would expect these increases in wing area would transfer through to the inline versions.

Improvements in the engines beyond the BMW801F 'power egg' might have born fruit. The far more advanced 18 cylinder BMW802 wasn't just bigger; it had the exhaust and inlet valves in axial or in tandem to the air flow(rather than circumferentially arranged) with the hot exhaust valve presenting to the air flow and the cooler inlet valve behind it. This gave better cooling and most importantly less drag through the engine. The cooling fan had a stator to compress the air to improve fan efficiency and could thus generate jet thrust at relatively low speeds as the heated air expanded from the cooling gills to recover cooling flow drag. The 802 also was to be capable of exhaust valve variable timming to tune resonant scavenging across the full RPM range. Apart from more power (perhaps 3000hp? WEP with MW50) less drag would be achievable. Non of these hypothetical improvements worsen engine conditions. This is just my theory of a BMW801 incorporating BMW802 technology.

The Fw 190 was a heavy fighter and the Ta 152, which used the same engine, heavier still. The Ta 152 would thus have a fundamental power to weight ratio issue compared to the Fw 190 (and its Allied competitors such as Griffon Spitfires which were hardly heavier than the Merlin versions) using the same advanced engines such as the Jumo 213EB (2500hp I suspect). The far more powerful Jumo 222 supposedly could be carried by the Ta 152 with minimal modifications and it was certainly slated for production in September 1944 (delayed to Feb 1945) for a range of aircraft.

 

[GregP]

The V-1 ws a purpose-built dive bomber. It just didn't have to be designed strong enough to make a pullout from the dive.

I think they were still launching a few in 1945. Heck, it didn't even take evasive action much less a pullout.

Come to think of it, the untimate dive bomber has to be the V-2 ...

Oh, but you probably meant MANNED dive bomber?

Couldn't resist ...

 

[GregP]

The V-1 ws a purpose-built dive bomber. It just didn't have to be designed strong enough to make a pullout from the dive.

I think they were still launching a few in 1945. Heck, it didn't even take evasive action much less a pullout.

Come to think of it, the untimate dive bomber has to be the V-2 ...

Oh, but you probably meant MANNED dive bomber?

Couldn't resist ...

 

[kool kitty89]

The DB605 rating seems to be for the problematical 1.42ATA that wasn't securely available till October 1943. The DB605 has a higher compression ratio which means that it expands its combustion products over a greater distance of travel and is therefore more efficient at converting hot gases into kinetic energy. The downside, especially for a fighter, is that there is now less energy available for jet thrust.

The lower compression ratio of the Jumo 211F would be an advantage in that respect too, and may have managed power levels close to the 211J if it had been tested/rated for C-2 or C-3 fuel. (albeit lower critical altitudes for given power levels due to the lack of intercooling but also avoiding any added drag from the intercooler -more significant if an embedded low-drag radiator was used rather than the typical annular Jumo one)

With fighter engine development in mind for the 211, its performance may have stayed ahead of the DB-601E and DB-605 at least until the Jumo 213 entered production. (or at least the practical rated power levels with the timeline of limits placed on the DB engines)

The Fw 190 was a much heavier aircraft than the Me 109 and Spitfire, I can't see it being competitive if equipped with a DB605 unless one is speaking of the 1944 water methanol injected ones or a possible version running on C3 96/125 fuel.

Had the structure been developed towards optimizations for a smaller, lighter powerplant early on (as was already the case to some degree on the early prototypes), much of that weight may have been avoided along with savings from using a lighter engine as well. Still, it would likely end up heavier than the Spitfire and 109, but then such was the case for the P-51, P-40, and even P-39.

Ground attack versions with the added heavy armor would obviously be heavier in any case, while specifically lightened high altitude fighter/interceptor versions should be the lightest with compromises made to armament and fuel capacity too. (somewhat like the 801 powers light/high alt fighter variants except with the potential for a hub cannon; 3 20 mm cannons would seem likely, 5 on heavy interceptors)

Heavier DB-603 and Jumo 213 powered variants would certainly make sense too, or even the Bramo 329 had it been pursued. (though that seems better used on bombers and heavy night fighters) I still don't know much on the 329's development, but it seems like the design was progressing early enough to be in line with the BMW 801 or DB 603 in development (if not ahead -running and meeting its 2000 ps design goal in 1938 ) and much more likely to be useful in a far more timely manner than the Jumo 222, DB 604, or BMW 802. (let alone the 803 or 804) I'm not sure, but continuing with the BMW 139 may have had time to (reliable) mass production advantages over the 801 as well. (and lower weight)

Interestingly some of the changes in technology from the DB601E to DB605A (such as changes in bearings) seem to have been a retrograde step that took a long time to debug. We would then have to ask as to whether a hypothetical DB603 that was not held up between 1937-1940 by Udet's decree is borrowing from 605 technology or DB601E technology.

Did Jumo not have the same shortage on ball bearings that Daimler Benz had to deal with or were they already making heavier use of other bearing types in the Jumo 211 line? (without the overhead in debugging that DB's transition suffered)

 

[Koopernic]

The lower compression ratio of the Jumo 211F would be an advantage in that respect too, and may have managed power levels close to the 211J if it had been tested/rated for C-2 or C-3 fuel. (albeit lower critical altitudes for given power levels due to the lack of intercooling but also avoiding any added drag from the intercooler -more significant if an embedded low-drag radiator was used rather than the typical annular Jumo one)

With fighter engine development in mind for the 211, its performance may have stayed ahead of the DB-601E and DB-605 at least until the Jumo 213 entered production. (or at least the practical rated power levels with the timeline of limits placed on the DB engines)


Had the structure been developed towards optimizations for a smaller, lighter powerplant early on (as was already the case to some degree on the early prototypes), much of that weight may have been avoided along with savings from using a lighter engine as well. Still, it would likely end up heavier than the Spitfire and 109, but then such was the case for the P-51, P-40, and even P-39.

Ground attack versions with the added heavy armor would obviously be heavier in any case, while specifically lightened high altitude fighter/interceptor versions should be the lightest with compromises made to armament and fuel capacity too. (somewhat like the 801 powers light/high alt fighter variants except with the potential for a hub cannon; 3 20 mm cannons would seem likely, 5 on heavy interceptors)

Heavier DB-603 and Jumo 213 powered variants would certainly make sense too, or even the Bramo 329 had it been pursued. (though that seems better used on bombers and heavy night fighters) I still don't know much on the 329's development, but it seems like the design was progressing early enough to be in line with the BMW 801 or DB 603 in development (if not ahead -running and meeting its 2000 ps design goal in 1938 ) and much more likely to be useful in a far more timely manner than the Jumo 222, DB 604, or BMW 802. (let alone the 803 or 804) I'm not sure, but continuing with the BMW 139 may have had time to (reliable) mass production advantages over the 801 as well. (and lower weight)


Did Jumo not have the same shortage on ball bearings that Daimler Benz had to deal with or were they already making heavier use of other bearing types in the Jumo 211 line? (without the overhead in debugging that DB's transition suffered)

Using roller bearings is unusual though admittedly superior from a friction point of view. I don't believe any allied engines used this technique.

Junkers Jumo made use of a different crankshaft design to the post roller bearing Daimler Benz engines, I suspect it was completely hollow, to distribute oil to both the big end bearings of the cranks and the bearings.

Kurfürst - Transcript of Generalluftzeugmeister meeting on 7th September, 1943.

This is a translated transcript on the issue of the 1.42 ata ban on the DB605A.
Reichsmarschall Hermann Göring, C-in-C, Luftwaffe.
Petersen, head of Erpobungstelle Rechlin.
Nallinger, CEO of Daimler Benz AG.
Scheibe, design engineer, Junkers AG.


Reichmarschall Göring : This means that with regard to the DB605, it is impossible to predict whether the engine is ever going to be a useful engine.

Eisenlohr : The engineering changes and the available test results reveal that there is a high probability that concerning the question bearings, the worst is behind us and the situation is going to improve, even if it is not going to be a robust engine, but at least one that can be run at maximum output by the frontline units with full justification. The testing at Rechlin proceeded completely well so far. Cuno reported that four weeks are still required for completion.

Reichmarschall Göring :You have the confidence in that can work out?

Eisenlohr : Yes sir.

Reichmarschall Göring : Nallinger, do you still have great confidence in your child?

Nallinger : On the basis of our latest testings we have the absolute confidence in that with the engineering changes I've reported, the engine will be fixed with regard to the bearings and the Startleistung is going to be cleared for use.

Reichmarschall Göring : What do you think, Petersen?

Petersen : I share this conviction and additionally am convinced that in conjunction with the oil centrifuge, the engine is going to be all right with regard to the bearings. That has always been the experience of the past, the maintenance people predicted that the engine is going to fail soon if the oil pressure dropped below a certain figure, below 100 atü. The new 177s with oil centrifuges have worked well so far, and no bearing failures have been suffered, so that I'm able to say: If these measures which I would like to call detail work are added, the oil centrifuge in conjection with the 605, that the bearing story can be considered to have ended.

Reichmarschall Göring : What do you say, Scheibe?

Scheibe : According to the understanding at Junkers, there should actually be no problem fixing the engine with regard to the bearings. If a far-fetched solution is necessary, then - as Nallinger elaborated - the lubrication has to be taken out of the crankshaft, if it's possible to use the example of the Jumo 211 as a reference which runs in the power-boosted forms N and P at virtually the same speeds without bearing problems.

*******************
The Jumo 211 seems to have been a solid engine and given the Jumo 211N was 1420hp and the Jumo 211P 1500hp they might indeed have offered as much as the BMW801D2 (around 1700hp) with C3 fuel perhaps more depending on grade. I don't know why it wasn't produced. I suspect the decision to make a large leap to the Jumo 213 came out of the need to not just match but substantially exceed BMW801 power which reached over 2000hp 1943/44.

The BMW801 was only 51 inches in diameter, any version to replace it would have to be no greater diameter.

 

[tomo pauk]

The DB605 rating seems to be for the problematical 1.42ATA that wasn't securely available till October 1943.
...

There was indeed a ban on using Notleistung (1.42 ata, 2800 rpm) until Oct 1942, as noted above.

The Fw 190 was a much heavier aircraft than the Me 109 and Spitfire, I can't see it being competitive if equipped with a DB605 unless one is speaking of the 1944 water methanol injected ones or a possible version running on C3 96/125 fuel

.

Several times it is mentioned in this and 'what to cancel' thread about why the Fw 190 was heavier than Spit or 109, plus what changes the possible V-12 engine brings. The BMW 801 was a heavy engine, even if we compare the liquid cooled engine PLUS it's cooling system - 150-250 kg of difference, depending on what engines are compared. Then we have the usually heavy armament of the Fw 190 - 4 cannons, 2 LMGs and all the ammo carried meant 4000-4100 kg ready to take off weight. 116 imp gals of fuel, vs. 84 and 88, plus the weight of protection for the tanks. Protection - almost 300 lbs standard (not the 'sturmbocks'), granted the 109 and Spit were also protected to some degree. Fully retractable covered U/C is strong enough to handle the 1800 kg (almost 4000 lbs) bomb under fuselage in FB variants - lets not try that with 109 or Spit.
We can use 'equalization' - halve the firepower, use only the bigger fuel tank, while installation of the V-12 shaves both weight and drag. Such a Fw 190, with 2 cannons and 80-90 imp gals, is at 3500-3600 kg? The Fw 190A3/U7 was at 3660 kg, with two cannons only and some 100 kg of protection deleted (but with extra 20 kg of fuel).

It needs a DB603, jumo 213 or possibly Jumo 222.

Once the P-47 (with even a limited external tank facility) arrived, it certainly does need the 603 or 213.

...
The Jumo 211 seems to have been a solid engine and given the Jumo 211N was 1420hp and the Jumo 211P 1500hp they might indeed have offered as much as the BMW801D2 (around 1700hp) with C3 fuel perhaps more depending on grade. I don't know why it wasn't produced. I suspect the decision to make a large leap to the Jumo 213 came out of the need to not just match but substantially exceed BMW801 power which reached over 2000hp 1943/44.

The 211P was produced IIRC, granted the 213A (and subsequent) make far more sense from late 1943 on. In order to match the 801D and the fully rated 605A, it needs a 'faster' supercharger, and that is what is the Jumo 211R all about - gains at altitude, while sacrificing low level power. The 211R probably never powered an operational aircraft, though.

The BMW801 was only 51 inches in diameter, any version to replace it would have to be no greater diameter.

This is a part of the answer to why the Fw 190D9 was faster than Fw 190A4-A8: it's powerplant was less draggy, with a smaller cross section.

 

[kool kitty89]

The 211P was produced IIRC, granted the 213A (and subsequent) make far more sense from late 1943 on. In order to match the 801D and the fully rated 605A, it needs a 'faster' supercharger, and that is what is the Jumo 211R all about - gains at altitude, while sacrificing low level power. The 211R probably never powered an operational aircraft, though.

Higher supercharger gear ratios applied earlier in the 211's life might also have allowed for more competitive altitude performance. (probably best applied in conjunction with the intercooler addition of the 211J) That of course, assumes that the existing supercharger (of the 211F/J -much improved over the 'spouted' earlier design) had headroom for reasonably efficient operation at higher speeds. Without the intercooler (or water injection) it may not have been worth the effort.

That also may have been an earlier option to combat the P-47's high alt performance. (increased boost limits with C3 fuel on top of that would help too, but perhaps not at P-47/B-17 heights -still important for brining the fight down a bit lower and for climb to get up there more quickly)

 

[tomo pauk]

What were the practical limits of the BMW 801D powered Fw 190 can be found in this test report. The Fw 190A3/U7 clocked 694 km/h at 7400 m (431 mph at 24278 ft), parly due to weight and drag reduction, partly by using external ram air intakes that increased usage of ram (not sure what is a proper term) to 60-95% vs. the internal intakes with the same value down to 22%.

 

[dedalos]

What were the practical limits of the BMW 801D powered Fw 190 can be found in this test report. The Fw 190A3/U7 clocked 694 km/h at 7400 m (431 mph at 24278 ft), parly due to weight and drag reduction, partly by using external ram air intakes that increased usage of ram (not sure what is a proper term) to 60-95% vs. the internal intakes with the same value down to 22%.

I always wondered what would be the performance of the A4 airframe in combination with the later BMW 801s of the 2100 ps. It would be an excellent vertion for the Eastern front. But the RLM could think of nothing else than more and more guns and more and more armour

 

[Mike Williams]

What were the practical limits of the BMW 801D powered Fw 190 can be found in this test report. The Fw 190A3/U7 clocked 694 km/h at 7400 m (431 mph at 24278 ft), parly due to weight and drag reduction, partly by using external ram air intakes that increased usage of ram (not sure what is a proper term) to 60-95% vs. the internal intakes with the same value down to 22%.

The following passage from Flugbericht Fw190 410230 V 34 Nr.1 should be kept in mind when discussing Fw 190 flight test figures from Focke-Wulf Flugzeugbau:

Ergebnis zu 1) Erstmalig ist im Kurvenblatt 1) die über der Meßstrecke ermittelte Staudruck eichung unter Berücksichtigung der Kompressibilität der Luft aufgetragen. In Zukunft werden alle mit den BMW 801 F und Jumo 312 Triebwerken ermittelten Geschwindigkeitsleistungen mit Berücksichtigung der Kompressibilität bekanntgegeben. Bei den Flugzeugen mit 801 D Motoren entfällt diese Umrechnung auch weiterhin, um die Vergleichsmöglichkeiten mit früher ermittelten Werten zu erleichtern.

That said, the comparison discussed in the report on Fw 190 528 is very interesting and worthy of note.

 

[wuzak]

I always wondered what would be the performance of the A4 airframe in combination with the later BMW 801s of the 2100 ps. It would be an excellent vertion for the Eastern front. But the RLM could think of nothing else than more and more guns and more and more armour

Was that a case of wanting to make it more effective at shooting down USAAF heavy bombers?

 

[kool kitty89]

Was that a case of wanting to make it more effective at shooting down USAAF heavy bombers?

The heavy A-8 variant was more optimized for ground attack and other low altitude work with weight gain from heavy armor to protect against ground fire. They were also the heaviest armed with 4 MG 151/20 cannons and 2 MG 131s.

The more high altitude fighter/interceptor oriented D-9 omitted the outer pair of cannons leaving 2 151/20s and 2 131 HMGs. The lightened high alt optimized 801 powered variants also tended to omit the outer wing cannons. (though I'd think omitting the cowl guns and reducing the ammunition load for the inboard 20 mm guns would be a more effective balance for weight, drag, and overall firepower)

 

[Koopernic]

What were the practical limits of the BMW 801D powered Fw 190 can be found in this test report. The Fw 190A3/U7 clocked 694 km/h at 7400 m (431 mph at 24278 ft), parly due to weight and drag reduction, partly by using external ram air intakes that increased usage of ram (not sure what is a proper term) to 60-95% vs. the internal intakes with the same value down to 22%.

This engine, seemingly the 1700hp 1.42 ata rated version, was tested in 1942, the incorporation of the ram inlet of the BMW801 into the wing root leading edge, as your other post shows, (rather than within the engine cowling) seems to have been designed into the 2400hp BMW 801F suggesting that this modification hadn't been introduced even 1.5 years after the test. Perhaps the superiority of the Jumo 213A versions partially traces back to this.

There was this life left in the radial versions.

The Fw 190 received two incremental wing area increases after the A3 variant and this would add some drag though not much.

The Fw 190D was being used to test the MG213 revolving breech gun, something that would boost fire power of the wing root guns by about 70% and make more practical the elimination of the outer wing guns. Some variants of the Fw 190D13 were supposed to receive wing tanks where the outer wing guns were. Considering the increased fuel thirst of these greatly more powerful engines more fuel was going to be critical. It's surprising the Luftwaffe didn't develop a long range air superiority version of the Fw 190A early on using this possibility.

There appear to have been two reasons for removing the wing guns of the Fw 190D9. One was the air situation in which superior allied quality and quantity demanded this kind of measure to give the pilots a chance of surviving. The other appears to be that the 'long nose' had a reduced roll rate. It's not immediately apparent why this should be so but I'm assuming that it was the problem of 'inertia coupling' latter experienced in jet fighters. An aircraft doing a roll does not rotate perfectly about its axis and there is a tendency of long thin aircraft with heavy mass at the end to 'sort off' centrifuge out, causing problems.

The Versions with the Jumo 213F, DB603LA and Jumo 213EB would have had the ability to carry mountings and propellers suitable for motor canon, this made practical the elimination of the synchronised machinge guns as well as the outer wing guns. Nevertheless the possibility of operating with the outer wing guns was always there form when the need and opportunity (no allied escorts) might arise.

Carrying sufficient armament is important. It might be safer to fly missions with a stripped down armament from a survivability point of view but if you aren't shooting down bombers why are you risking your life flying missions at all?


Up to the Fw 190A5 variants modified for ground attack were given an umrustung or U designation. After the A6 versions designed for ground attack were called Fw 190F though aircraft from the Fw 190A6 could still be modified. I suspect that a lot started to change after that (1943), including propellors, WEP devices, bomb release sequencers, armour distribution etc.

 

[Denniss]

The heavy A-8 variant was more optimized for ground attack and other low altitude work with weight gain from heavy armor to protect against ground fire. They were also the heaviest armed with 4 MG 151/20 cannons and 2 MG 131s.

No armor vs ground attack in A-8, that's the F-8. Armament was already available in the A-7. Major diff between A-7 and A-8 is the option to install an aux fuel tank (standard autumn 44). Some weight was gained with adoption of 801Q-2 engine (summer/autumn 44, larger oil tank with thicker armor).

 

[dedalos]

Once again, as in the case of the Me 109, RLM was unwilling to insert improvements from fear of losing some production

 

[Milosh]

The Fw 190 received two incremental wing area increases after the A3 variant and this would add some drag though not much.

Only have heard of structural changes. What were these area increases?

 

[GregP]

Came across a US study of the evolution of fighter tactics and was interested to see a paragraph about the tactics typically used by P-51 pilots in WWII in whgich they used the P-51's good instantaneous turn and roll and the ability to zoom climb but avioded getting into long turning fights, particularly against better-turn aircraft like the Fw 190. There was no elaboration about the "better-turning" part, just the statement.

That's the first time I heard it expressed quite that way and this seems like a good place to post it.

 

[kool kitty89]

No armor vs ground attack in A-8, that's the F-8. Armament was already available in the A-7. Major diff between A-7 and A-8 is the option to install an aux fuel tank (standard autumn 44). Some weight was gained with adoption of 801Q-2 engine (summer/autumn 44, larger oil tank with thicker armor).

I also forgot to mention earlier that the added external ram air intakes added more to altitude performance but not much/any advantage at low level given the drag imparted, so the A-8 was already optimized for mid/low alt fighter duties as it was. (a BMW powered variant to be more directly competitive with the D-9 likely should have adopted those intakes though)

 

[Denniss]

Never seen external intakes on A-9. Still a mystery why they were not introduced for West Front use, at least as unit mod/hack.