# Optimize the FW190 for the Eastern Front



## wiking85 (Mar 9, 2015)

Most Fw190s served against the Western Air Forces and new models were optimized for threats in the west that weighed down the fighters that ended up serving in the East. Heavier armor and armament for bomber killing affected all German fighters from 1942 on, but how could the Fw190 have been optimized to fight in the East against the new La-5s and -7s for combat under 20k feet? 
Focke-Wulf Fw 190 - Wikipedia, the free encyclopedia


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## tomo pauk (Mar 9, 2015)

Up-rate the engines ASAP, via increased boost. Works fine under 6 km.
Remove the fuselage MGs, retain 4 canons (hopefully all 4 MG 151/20E) since there are plenty of Il-2 and Pe-2 around, plus LL A-20s and B-25s. A more streamlined belly rack will also be good, for less of the speed loss.


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## wiking85 (Mar 9, 2015)

tomo pauk said:


> Up-rate the engines ASAP, via increased boost. Works fine under 6 km.
> Remove the fuselage MGs, retain 4 canons (hopefully all 4 MG 151/20E) since there are plenty of Il-2 and Pe-2 around, plus LL A-20s and B-25s. A more streamlined belly rack will also be good, for less of the speed loss.



Were they historically able to boost the BMW engine earlier than the did historically? If so why did they hold back?


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## tomo pauk (Mar 9, 2015)

The BMW 801D was fully rated (2700 rpm, 1.42 ata) by October 1942. About in the same time the Fw-190 was introduced in the Eastern Front, and was certainly better than the La-5, or anything the Soviets were able to throw in. The La-5F evened that a bit in second half of 1943.
Fw-190s used overbosting via C3 injection by that time, tough the system seem to be limited for Jabo versions only, and only for 1st supercharger gear. So a more prolific use of that system will benefit all of the Fw-190s, also using it in 2nd S/C gear. The 'plain' overboosting was tested in second half of 1943 (~ 1st Sept 1943), so usage before 1944 was probably out of question. The C3 injection involves smaller rise of cylinder temperatures, the 'plain' overboosting is simpler and uses less fuel.


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## wiking85 (Mar 9, 2015)

tomo pauk said:


> The BMW 801D was fully rated (2700 rpm, 1.42 ata) by October 1942. About in the same time the Fw-190 was introduced in the Eastern Front, and was certainly better than the La-5, or anything the Soviets were able to throw in. The La-5F evened that a bit in second half of 1943.
> Fw-190s used overbosting via C3 injection by that time, tough the system seem to be limited for Jabo versions only, and only for 1st supercharger gear. So a more prolific use of that system will benefit all of the Fw-190s, also using it in 2nd S/C gear. The 'plain' overboosting was tested in second half of 1943 (~ 1st Sept 1943), so usage before 1944 was probably out of question. The C3 injection involves smaller rise of cylinder temperatures, the 'plain' overboosting is simpler and uses less fuel.



What is C3 injection and how is it different than normal boost?


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## wiking85 (Mar 9, 2015)

Also this says C3 injection wasn't ready until mid-1943:
FW 190 A-5 Performance


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## tomo pauk (Mar 9, 2015)

That is reasonably timely, considering that 801D was fully rated for some 8 months before that.



wiking85 said:


> What is C3 injection and how is it different than normal boost?



It employs a separate system (pump, tubes, nozzles) that 'normal' over-boosting does not use. The C3 injection is a form of ADI (anti-detonant injection), where the extra fuel is not burned in cylinders, but it cools the charge, so more boost can be applied. Eventually the conclusion was that 'normal' over-boosting was about as useful, and engines were capable to handle greater temperatures.
Both systems were good for up to about 1.58-1.65 ata, vs. usual 1.42 ata. That meant 1900-2000 PS in low gear, and up to 1650 PS in high gear (not sure the C3 injection system was ever tested/allowed for high S/C gear)


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## wiking85 (Mar 9, 2015)

So if the C3 system is not around until mid-1943 and only then on a limited basis (I'm guessing the extra complications and cost won't make it scalable) we are then only left with the removal of the fuselage guns; why them though? They were supposed to be the most accurate. Why not take off one set of cannons on the wings instead? They were heavier and the lower ammo ones (the outside ones had only 140 RPG instead of the 250 for the inner ones) could be dropped instead with greater weight savings, thus keeping the more accurate, lighter fuselage mounted guns. Were those more drag inducing?


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## tomo pauk (Mar 9, 2015)

The 4 cannon set-up has about twice the firepower vs. the 2 cannons and 2 LMGs. The fuselage MGs might be accurate, they don't mean anything for killing an Il-2 or any of decent twin the VVS was operating.


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## wiking85 (Mar 9, 2015)

tomo pauk said:


> The 4 cannon set-up has about twice the firepower vs. the 2 cannons and 2 LMGs. The fuselage MGs might be accurate, they don't mean anything for killing an Il-2 or any of decent twin the VVS was operating.



It does matter to fighting Soviet fighters. In terms of MGs they were MG131s, which were .51 caliber bullets that the Sturmovik was certainly not immune to, nor were Soviet twin engines.  
Erich Hartmann made a carrier of downing Sturmoviks in his Bf109 whose heaviest weapon was the MG151. Having two cannons and large caliber MGs would have been even more effective than a single MG151 (or 20mm Motorkanone) and two MG17s.
Erich Hartmann - Wikipedia, the free encyclopedia


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## tomo pauk (Mar 9, 2015)

The MG 131 installation involves adding the drag, that will be as great as 2 extra cannons? Part of the reason the Fw 190A-8 was 6-10 km/h slower than the 190A-6/A-5. And it still has maybe 60% of firepower than a 4-cannon Fw-190.



> Erich Hartmann made a carrier of downing Sturmoviks in his Bf109 whose heaviest weapon was the MG151



Problem was that there was maybe 1% of German (or other country's) pilots that were as good pilots/marksmen as Bubbi was. The run-on-the-mill pilot needed plenty of firepower vs. the target Hartmann will kill with a single cannon.
We can recall that Germans were not shy to use the gondola cannons on the Bf 109, despite the known performance maneuverability loss induced.


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## wiking85 (Mar 9, 2015)

tomo pauk said:


> The MG 131 installation involves adding the drag, that will be as great as 2 extra cannons? Part of the reason the Fw 190A-8 was 6-10 km/h slower than the 190A-6/A-5. And it still has maybe 60% of firepower than a 4-cannon Fw-190.


I'm not clear on what you're saying here. What was the reason the A-8 was slower? I thought it was the extra armor, addition of the 30mm cannons, a larger fuel tank, and more powerful, heavier engine. Not sure if the new canopy changed the aerodynamics.
List of Focke-Wulf Fw 190 variants - Wikipedia, the free encyclopedia




tomo pauk said:


> Problem was that there was maybe 1% of German (or other country's) pilots that were as good pilots/marksmen as Bubbi was. The run-on-the-mill pilot needed plenty of firepower vs. the target Hartmann will kill with a single cannon.
> We can recall that Germans were not shy to use the gondola cannons on the Bf 109, despite the known performance maneuverability loss induced.



Bubi was only as good as he was due to getting close where he did not need to be a marksman and he was coached on that by more senior pilots, so it was not unique to him. In fact I've seen FW190 handbooks that recommend the same. Correct me if I am wrong, but the gondola guns were only used against Western heavy bombers (the viermots) and not on the Eastern Front. Bubi was only using standard gun layouts in the East, sans gondolas. The only reason other pilots needed the extra guns was due to opening up too far away and wasting a lot of ammo trying for long range kills; basically using 'spray and pray' tactics.


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## davebender (Mar 9, 2015)

Design Fw-190 for DB603 engine from 1937 onward with annular radiator. Hence wing will be further forward, eliminating need for fuselage extension on historical Fw-190D. This results in a lighter and more compact aircraft.

Armed with 3 x 20mm cannon. One in hub plus two inboard wing positions. Outer wing weapon positions can be omitted from the design. Cowl machineguns can be omitted too. Instead hub cannon gets twice as much ammo as wing cannon since it's inherently more accurate.

Resulting aircraft should perform a bit better then historical Fw-190D9 and should be in mass production at least as early as historical Fw-190A. Engine won't require C3 fuel as historical Fw-190A did and you avoid technical problems of BMW801 engine overheating.


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## tomo pauk (Mar 9, 2015)

wiking85 said:


> I'm not clear on what you're saying here. What was the reason the A-8 was slower? I thought it was the extra armor, addition of the 30mm cannons, a larger fuel tank, and more powerful, heavier engine. Not sure if the new canopy changed the aerodynamics.
> List of Focke-Wulf Fw 190 variants - Wikipedia, the free encyclopedia



The A-8 have had the same engine as, for example, an A-4 - BMW 801D. It was allowed for over-boost, however. 30mm cannons were not a standard on the A-8, nor it was a heavier armor suite. The extra fuel tank will cost some speed, indeed. Here is how much the MG 131 vs. MG 17 cost in speed (source):

_From this loss is about 3 mph (5 km/h) from the two additional MG 151 runs *and ~ 6 mph (10 km/h) due to the changes for the installation of the MG 131 cover front windscreen* (see Flight Report Fw 190/861 with 2 MG 17 + 4 MG 151)._



> Bubi was only as good as he was due to getting close where he did not need to be a marksman and he was coached on that by more senior pilots, so it was not unique to him.



Hence I've mentioned 'pilot/marksman' - you need to have at least one of the two if you want a single cannon to suffice. Not granted for any airforce of ww2.



> In fact I've seen FW190 handbooks that recommend the same.



Could you please point me to the excerpts? 



> Correct me if I am wrong, but the gondola guns were only used against Western heavy bombers (the viermots) and not on the Eastern Front. Bubi was only using standard gun layouts in the East, sans gondolas. The only reason other pilots needed the extra guns was due to opening up too far away and wasting a lot of ammo trying for long range kills; basically using 'spray and pray' tactics.



The Soviets have tested the captured Bf-109G2 with gondolas, and same 109s were used on the MTO. LW certainly judged the Bf-109 to be under-armed as-is, hence such boost in the firepower even if it involves speed, RoC and roll penalties.


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## wiking85 (Mar 9, 2015)

tomo pauk said:


> The A-8 have had the same engine as, for example, an A-4 - BMW 801D. It was allowed for over-boost, however. 30mm cannons were not a standard on the A-8, nor it was a heavier armor suite. The extra fuel tank will cost some speed, indeed. Here is how much the MG 131 vs. MG 17 cost in speed (source):
> 
> _From this loss is about 3 mph (5 km/h) from the two additional MG 151 runs *and ~ 6 mph (10 km/h) due to the changes for the installation of the MG 131 cover front windscreen* (see Flight Report Fw 190/861 with 2 MG 17 + 4 MG 151)._


Then the argument is what is more valuable, the higher velocity Mg131 with greater accuracy due to mounting and speed, or the hitting power and greater speed of the 2 additional cannons in wing mount? 

The Mg151/20 was 700mps velocity, the Mg131 was 750mps.



tomo pauk said:


> Hence I've mentioned 'pilot/marksman' - you need to have at least one of the two if you want a single cannon to suffice. Not granted for any airforce of ww2.


I'm not saying a single would be enough, rather that a pair of MG151/20s in the wing roots and a pair of MG131s in the fuselage would suffice, especially if they closed in enough (IIRC within 300m for best effect).



tomo pauk said:


> Could you please point me to the excerpts?


They were in here:
La-5/7 vs Fw 190: Eastern Front 1942-45 (Duel): Dmitriy khazanov, Jim Laurier, Gareth Hector: 9781849084734: Amazon.com: Books



tomo pauk said:


> The Soviets have tested the captured Bf-109G2 with gondolas, and same 109s were used on the MTO. LW certainly judged the Bf-109 to be under-armed as-is, hence such boost in the firepower even if it involves speed, RoC and roll penalties.


Any idea how common they were in the East? Also when did they get ahold of them? They tested a Me410 too, but AFAIK those weren't used in the East either, but were captured at the end of the war.


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## dedalos (Mar 9, 2015)

I would take a more aggressive approach for a Eastern front Air superiority specialized FW190A

1)Normal take off weight 3800kgr. That means A-5 airframe, No MGs ,just 2 20mm guns with 250 rpg. More than enough for the Eastern front. Also no fancy radios. No bomb rack for the majority of the missions

2) Wing tanks in place of the external 20mm guns, used only when neseccary

3) Fully covered main wheels and fully retractble tail wheel

4)1.65 boost as soon as possible, wide blade propellers as soon as possible

The above are historical very possible
I would also propose fowler type combat flaps but as far as i know the german did not ever developed such devices

The ultimate performing Fw would be all the above in combination with Db603 with C3,( no extentions,standart A5 fuselage)

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## tomo pauk (Mar 9, 2015)

wiking85 said:


> Then the argument is what is more valuable, the higher velocity Mg131 with greater accuracy due to mounting and speed, or the hitting power and greater speed of the 2 additional cannons in wing mount?
> The Mg151/20 was 700mps velocity, the Mg131 was 750mps.



The Mine shell was fired at 805 m/s, so the MG 151/20 takes the lead in MV, too. The MG 131 fired faster, though, 900-930 rpg (minus the cost of being synchronised - 10-15%?), the MG 151/20 was at 630 rpg (Mine shell) to 695 (HE-I shell). All in all, I'd go with 4 cannons rather than with 2 + 2. 



> I'm not saying a single would be enough, rather that a pair of MG151/20s in the wing roots and a pair of MG131s in the fuselage would suffice, especially if they closed in enough (IIRC within 300m for best effect).



Enough indeed to kill a fighter. The VVS fielded other, more sturdier types too, and 4 cannons are a better bet there. 



> They were in here:
> La-5/7 vs Fw 190: Eastern Front 1942-45 (Duel): Dmitriy khazanov, Jim Laurier, Gareth Hector: 9781849084734: Amazon.com: Books



Thanks for the link. I was hoping that you'd point me to real manuals 



> Any idea how common they were in the East? Also when did they get ahold of them? They tested a Me410 too, but AFAIK those weren't used in the East either, but were captured at the end of the war.



I don't know how much the gondolas were used there. The G-2 with gondolas was tested mid war, the report can be found at Kurfurst.


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## tomo pauk (Mar 10, 2015)

dedalos said:


> ...
> I would also propose fowler type combat flaps but as far as i know the german did not ever developed such devices



Japanese have had the so called 'butterfly flaps' used from the 1st Ki-43s on, so a little feedback could come in handy?



> The ultimate performing Fw would be all the above in combination with Db603 with C3,( no extentions,standart A5 fuselage)



With C3 it would be circa 2000 PS; the B4 + MW 50 also makes sense here. I'd go for 3 cannons, one of them 30mm once available. The type would be much more needed in the West, however.


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## Totalize (Mar 10, 2015)

I believe the 190 had fairly high wing loading. for dog fighting under 20K feet I would remove the MG/FF's or later the MG151/20's from the outer wings to ease the wing load. Definitely keep the fuselage guns.


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## wiking85 (Mar 10, 2015)

Totalize said:


> I believe the 190 had fairly high wing loading. for dog fighting under 20K feet I would remove the MG/FF's or later the MG151/20's from the outer wings to ease the wing load. Definitely keep the fuselage guns.



Actually yeah, its 49lbs/square foot wing loading is about 10 lbs higher than any fighter I can find.


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## davebender (Mar 10, 2015)

That's not the end of the world as long as the aircraft has excellent roll.


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## tomo pauk (Mar 10, 2015)

The Fw 190A-6 was at 4100 kg fully loaded, clean, 18.3 m^2 wing area. Works at 45.89 lbs/sq ft. Even the 190A-8 is at 48.12 with 4300 kg (not that I champion the A-8 ).
Just how much the fuselage MGs are worth in combat; LMG vs. HMG; how big there is a save/gain/loss with HMGs installed and outer cannons deleted?


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## tomo pauk (Mar 10, 2015)

Tests of the Fw 190A-4 with over-boosted engine, March-April 1943: link. 
Max boost was 1.7 ata at SL at max possible speed (= max ram), gain in power was judged to be at 450-500 PS (roughly 2150-2200 PS total). Tests only for 1st S/C gear.


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## Koopernic (Mar 10, 2015)

wiking85 said:


> Were they historically able to boost the BMW engine earlier than the did historically? If so why did they hold back?



The primary reason that they were able to over boost the engine was the improvement in C3 fuel. I posted a link to Allied intelligence files at 
fischer-tropsch.org in this forum that I can't find right now.

Basically C3 fuel, starting in 1940-1943 was 92/110, 93/115,94/120, 96/125 and continued to grow nearly reaching the standard of allied 100/130. The last figure in 1943 seems to coincide with the increase of maximum allowable boost from 1.42 ata to 1.65 ata. This took power of the BMW 801D2 from 1700hp to 1900hp at sea level in 1943. In early 1944 another modification was introduced in which much of the C3 fuel was sprayed into the eye of the supercharger instead of directly injected into cylinders. This could give as much as 2050hp. The injection into the supercharger precooled the air, contracting it, and allowing more air and fuel mass to be forced into the cylinders. This was refered to as "C3 einspritzung". This was initially only available below 1000m and only applied to the ground attack versions of the Fw 190 (the G and F) which were in need of a way of overcoming their speed loss when carrying bombs.

Overboosting means a denser air/fuel mass is burning in the engine so more heat needs to be handled by the cooling systems and there may have been issues with lubrication, oil coolers even spark plugs but generally minor and generally solvable with time restrictions. If they had of increased compression ratio instead they would have gotten more power without the heat and without tapping out the supercharger.

Hence introduction of increased boost is dependant on the German Petrochemical Industries ability to produce large volumes of high grade fuel. In general the Germans synthesised iso-octane to boost their hydrogenation based fuels but they laid down alkylation plants in 1940 to produce alkylate to make this more economical, I think only 1 maybe two got operational.

These changes were standardised on the BMW801TS from mid 1944, this engine replaced the 801D2. The "E" and its fighter engine the "S" had improvements, I think the heads were precision vacuum caste for greater strength. (The T prefix indicates a modular power package with oil cooler, gearbox, propeller)

The TS engine Fw 190A9 from mid 1944 onwards had a supplementary tank that could carry either fuel or theoretically MW50. There had been some problems with MW50 but these seem to have been from direct cylinder injection and I believe the main reason it was avoided was its inconvenience. Towards the end of the war the engine seems to have been released for B4+MW50 lieu of C3 shortages. I'm guessing the improved heads may have made this more acceptable.

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## tomo pauk (Mar 11, 2015)

The "C3 einspritzung" was used already in Summer of 1943 by the bomb-lugging Fw-190s.

FWIW, the power chart for the DB 603A, with added lines for the BMW 801D (red, Notleistung; pink is overboost roughly) and Jumo 213A (blue, Notleistung). The DB 603A really trumps the BMW, not only power-wise, but it cuts drag, allows for a big gun to be carried centrally, the intake will use the ram air in a convenient fashion so the aircraft's rated height will be at circa 7 km. Can use MW 50 for even more power, especially under 6 km (no ram), Notleistung can be used for 5 minutes instead of 3 min for the 801. 
Problem with DB 603A is that it is not that reliable and available in 1943.
(open the pic separately for hi-res)


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## dedalos (Mar 11, 2015)

tomo pauk said:


> The "C3 einspritzung" was used already in Summer of 1943 by the bomb-lugging Fw-190s.
> 
> FWIW, the power chart for the DB 603A, with added lines for the BMW 801D (red, Notleistung; pink is overboost roughly) and Jumo 213A (blue, Notleistung). The DB 603A really trumps the BMW, not only power-wise, but it cuts drag, allows for a big gun to be carried centrally, the intake will use the ram air in a convenient fashion so the aircraft's rated height will be at circa 7 km. Can use MW 50 for even more power, especially under 6 km (no ram), Notleistung can be used for 5 minutes instead of 3 min for the 801.
> Problem with DB 603A is that it is not that reliable and available in 1943.
> ...



And let s forget that the 801D was using C3 fuel while db603 B4. And still the 801 was inferior!
I believe that after 1942 the 801 was a really BAD engine as fighter engine. It crippled the Fw190 during the most important war years. In my opinion the Fw190/Bmw801 combination enjoys today much more fame than historicaly deserves.


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## wiking85 (Mar 11, 2015)

dedalos said:


> And let s forget that the 801D was using C3 fuel while db603 B4. And still the 801 was inferior!
> I believe that after 1942 the 801 was a really BAD engine as fighter engine. It crippled the Fw190 during the most important war years. In my opinion the Fw190/Bmw801 combination enjoys today much more fame than historicaly deserves.



Yeah, but the DB603 never managed to reach the 100 hours between overhauls by the end of the war like the BMW did.


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## tomo pauk (Mar 11, 2015)

dedalos said:


> And let s forget that the 801D was using C3 fuel while db603 B4. And still the 801 was inferior!
> I believe that after 1942 the 801 was a really BAD engine as fighter engine. It crippled the Fw190 during the most important war years. In my opinion the Fw190/Bmw801 combination enjoys today much more fame than historicaly deserves.



Don't think the 801 was a bad fighter engine in 1943. It was just fully rated in October 1942, and it's power was sufficient before late 1943. Where it came short was the air intake layout, it needed an external intake that is both not that draggy and not 'squashed', so the aircraft rated height is at about 7 km, instead at 6.3 km. Let's not forget that both RAF and USAF specified the Fw-190 as a target to equal or better (though the Bf-109F-4/G-2 were also tough things to beat). From Autumn of 1941 until 1943, the Fw 190 was very much an useful fighter, and in many of it's properties the best in the world.

Now for winter of 1943/44 and on, the Fw-190 certainly needed a better engine. Whether the DB 603, Jumo 213, or even the 2-stage BMW 801 if it can be pulled out.


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## wiking85 (Mar 11, 2015)

tomo pauk said:


> Don't think the 801 was a bad fighter engine in 1943. It was just fully rated in October 1942, and it's power was sufficient before late 1943. Where it came short was the air intake layout, it needed an external intake that is both not that draggy and not 'squashed', so the aircraft rated height is at about 7 km, instead at 6.3 km. Let's not forget that both RAF and USAF specified the Fw-190 as a target to equal or better (though the Bf-109F-4/G-2 were also tough things to beat). From Autumn of 1941 until 1943, the Fw 190 was very much an useful fighter, and in many of it's properties the best in the world.
> 
> Now for winter of 1943/44 and on, the Fw-190 certainly needed a better engine. Whether the DB 603, Jumo 213, or even the 2-stage BMW 801 if it can be pulled out.



The BMW 801S was better than the DB603.


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## tomo pauk (Mar 11, 2015)

Before late 1944, it is not any better - there is no any of those around to power aircraft. The DB 603A is old news by then.
From late 1944 on, the DB 603E can give comparable power, it is more streamlined, the air intake is better, MW 50 can be used, big gun can be installed between the banks, it will work well on B4 fuel. The two stage 603L and 603LA are in the pipeline, the BMW was unable to offer a workable producible 2-stage engine at all.


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## Totalize (Mar 12, 2015)

davebender said:


> That's not the end of the world as long as the aircraft has excellent roll.



Agreed, but if I recall the 190 while having a very nice roll rate capability was subject to high speed stalls, so if you have an LA-5 on your tail and you rolled away too sharply she flipped over on you in a stall. This is very dangerous in an East Front dog fight because many of them took place at very low levels. Stalling it in a sharp roll often meant she went into the ground along with the pilot as there was not enough altitude to recover. The Luftwaffe lost droves of young inexperienced 190 pilots in this manner in the latter part of the war.


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## Greyman (Mar 13, 2015)

Rolling fast wont do anything like that to your aircraft - unless rolling imparts heavy yaw forces on that type and you mush/spin out that way.

The Fw 190's high speed stalls would come from turning (pitch).

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## Koopernic (Mar 14, 2015)

Greyman said:


> Rolling fast wont do anything like that to your aircraft - unless rolling imparts heavy yaw forces on that type and you mush/spin out that way.
> 
> The Fw 190's high speed stalls would come from turning (pitch).



The Fw 190 had nice stalling characteristics when not under high G. Under extremely high G, in say a tight turn, the Fw 190 could snap into a spin. Recovery was however very easy and quick. Fw 190 pilots used it as a standard tactical combat manoeuvre simply flipping into a spin and dropping a few hundred feet. One gets the impression spin recovery was much better than a P-51 which could take thousands of feet.

The reason is that under extreme load the wing tips of the twin spar wing would twist thereby reducing the 2 degree geometric twist over the aileron area and lead to a premature stall. once the load was off the good characteristics would return. Focke-Wulf was aware of the source of this characteristic, we have their report, and must have looked at revising the wing. Certainly the Ta 152B/C and Ta 152H had completely revised wings structurally. I personally suspect the Fw 190A9/D9 onward might have had some improvements since US Navy pilots who evaluated the Fw 190D said the power on stall characteristics was good. Fw 109's were seldom flown in tight sustained turning fights.


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## tomo pauk (Mar 17, 2015)

koolkitty said:



> The advantage of the 801 I can see would be higher max continuous power than the 605, provided WM/50 is implemented. (same reason the 605+WM/50 was unattractive on the 190 -the high alt models still seem like they might have been worth the trade-offs though, potential gain in range/endurnace too, and mounting space for a motorkannone, but that's getting into a whole other topic with alternate Fw-190 variants)



The max continuous power of the engine will not be affected by MW 50. The fully rated DB-605A/AM was making 1080 PS at 5.5 km, vs. 1180 PS of the BMW 801D, however the BMW is more draggy, it is heavier, and it consumes more (both total and specific consumption). Installing a 20mm or even 30 mm to fire through the prop means less drag than having 2xMG 131s under cowling of the Fw 190.
The DB 605AM was making about as much power at 4-5 km as the the overboosted BMW 801D. The DB 605AS/ASM really trump the BMW 801D at altitude: more power, less weight, less drag.




> And there you go into the topic of diverting engines to the 190 as well, granted with the more universally advantageous 603. (that airframe seemed to be one of the most sensible places to be puting 603s as well as 213s, and the 603 allowed for a centerline cannone mounting as well)
> The DB-605 AS(M) still seems like a useful candidate too, though, especially in as far as matching/beating the Mustang above 20,000 ft. (compared to using the 801, not the 603 or 213)



As above - especially the 605ASM would be a very useful engine for hi-alt work - at 6.4 km (21000 ft) it makes 1500 PS, or same as the DB 603A, with less weight bulk. Problem with 605ASM is a crucial one for a tool of warfare - it is available too late to matter, and any engine produced is needed for the Bf-109 to keep them competitive at ETO/MTO. The 605 AS was good for 1200 PS at 8 km (~26250 ft). 
With full commitment to the Fw-190 plus DB 603, LW can have several hundreds of such 190s before Big Week ( the 605AS/ASM is too late for that). Even if they cannot match the Merlin Mustang, the performance disadvantage would be far smaller than what the Fw-190As were against - the Fw 190 with 603A of 1944 should be at least as good as a working Fw-190D-9.


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## kool kitty89 (Mar 18, 2015)

tomo pauk said:


> The max continuous power of the engine will not be affected by MW 50. The fully rated DB-605A/AM was making 1080 PS at 5.5 km, vs. 1180 PS of the BMW 801D, however the BMW is more draggy, it is heavier, and it consumes more (both total and specific consumption). Installing a 20mm or even 30 mm to fire through the prop means less drag than having 2xMG 131s under cowling of the Fw 190.
> The DB 605AM was making about as much power at 4-5 km as the the overboosted BMW 801D. The DB 605AS/ASM really trump the BMW 801D at altitude: more power, less weight, less drag.


So a universally good fit for the 190, except perhaps for fighter-bomber specific variants.

You've got those DB-605's slated for Bf-109s and 110s, so politics aside, plans would have had to be in motion to shift production earlier. Expand Fw-190 production or risk having fewer engines avilable to 109s. (110s might be a significant loss too and retooling them to BMW-801s might or might not have worked -pushing those engines onto Ju-88s might have made more sense though ... and if the 110s were /actually/ needed, Jumo 211s might have been adequate and much easier to displace the 601s/605s with than 801s, including the issue of limited range/fuel capacity of the 110)

It's somewhat like the situation with the Hurricane vs Spitfire in terms of keeping the older type in production and even sacrificing better engines to the weaker type to allow useful performance when insufficient numbers of either airframe are available. (ie no Spitfire III) Granted, less extreme there since the spitfire was closer to Bf-109 in performance, and it ended up getting the slightly smaller/lighter Merlin 45 at the expense of low altitude power. But there, the British wanted to replace the Hurricane outright and push more Spitfires as much as possible, whereas the 190 wasn't pushed as a total replacement outright and emphasis on expanding it to maximum priority production didn't have quite the same situation evolving. Plus that was for the Merlin XX series ... more akin to the late model DB-601s which had less clear advantages on the Fw-190 (might have been good for longer range/endurance tasks) but the DB-605 was more akin to allocation of the Merlin 60/70 series. (cramming merlin 61/66s on Hurricanes would have been a waste ... though this overall comparison is probably closer to comparing spitfire to mustang production, just less comparable due to the separate countries -and the P-40 and P-39 hardly compare to the specific trade-offs of the 109 vs 190)

Relegating some 109s to be Jumo 211 powered might have been a reasonable trade-off (for sheer volume production if 190s couldn't totally supplant 109 volumes), but performance would be limited and no motor cannon support was provided. (go back to using wing cannons as standard?) The 801 would seem a bad fit for the 109. Heavy, draggy, and fuel hungry. Maybe use Jumo powered 109s on the Eastern front where altitude performance wasn't as critical? (maybe have more precedent for MW/50 systems being developed for the 211?) Somewhat like the Avia S-199 but less of a hack job with properly mated prop and reduction gearing, and preferably J/N/P models rather than F.

Plus, relegating more of those 'lesser' 109s to the Eastern front and diverting even more 190s to the ETO might have been a worthwhile trade-off. (especially with the potential potency of DB powered 190 variants)

Bombers/heavy/night fighters with more 801s, 190s with more 605s (and 603s), and supplemental 109s with 211s might have made some sense. (again, if 109s couldn't be phased out entirely)

There's also the He-100 to consider, which might have made an even better fit for the DB-605 (or 601) but was also a tighter/limited design. The 190 is bigger and heavier, but remarkably flexible in overall design, more space for expansion and weight gain, fuel, armament, and a variety of engines. (plus it was in development at the same time as the He-100, so unless the He-100 was actually easier to manufacture, ramping up/second sourcing 190 production would seem most useful)

That's aside from other 'might have been' aircraft that would mate well with the 605 ... or any of the engines really. (but the Fw-187 is on my mind, and the Jumo 211, DB-601, and DB-605 would be the best fits for that)




> As above - especially the 605ASM would be a very useful engine for hi-alt work - at 6.4 km (21000 ft) it makes 1500 PS, or same as the DB 603A, with less weight bulk. Problem with 605ASM is a crucial one for a tool of warfare - it is available too late to matter, and any engine produced is needed for the Bf-109 to keep them competitive at ETO/MTO. The 605


Again, this seems a bit like the Hurricane production situation and only relevant if it was impossible to replace 109 volume production with other types. (albeit a much more limited argument due to the scarcity of ASM engines)

Keeping 109s competitive in the ETO/MTO is only a problem if there's no alternative to displace them entirely ... at least outside of the Eastern front.


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## tomo pauk (Mar 18, 2015)

kool kitty89 said:


> So a universally good fit for the 190, except perhaps for fighter-bomber specific variants.



Not that a good fit before late 1943, until the DB 605A was allowed for 2800 rpm and 1.42 ata. The 605AM is also not available before 1944. I'd still prefer the DB 603 and Jumo 213 for West-bound Fw-190s, indeed the BMW 801 seem like the best bet for fighter-bomber versions of the Fw-190. Also for fighters for Eastern front, with it's good/excellent power under 5-6 km alt.



> You've got those DB-605's slated for Bf-109s and 110s, so politics aside, plans would have had to be in motion to shift production earlier. Expand Fw-190 production or risk having fewer engines avilable to 109s. (110s might be a significant loss too and retooling them to BMW-801s might or might not have worked -pushing those engines onto Ju-88s might have made more sense though ... and if the 110s were /actually/ needed, Jumo 211s might have been adequate and much easier to displace the 601s/605s with than 801s, including the issue of limited range/fuel capacity of the 110)



Methinks it is a question of timing. The BMW 801D is IMO the best engine for the Fw-190 until the DB 603A is available reliable (late 1943?). The Jumo 213A is there also by late 1943/early 1944 - that means the Jumo 211 is slowly phased out from production/use, and the promising 'fighter version', the 211R will not be produced. The 211J/N/P in the Bf 109 will cut it's performance. I'd push 213s in the Fw-190 (along with DB 603s), so the Bf-109 can keep the Db 605s.




> Relegating some 109s to be Jumo 211 powered might have been a reasonable trade-off (for sheer volume production if 190s couldn't totally supplant 109 volumes), but performance would be limited and no motor cannon support was provided. (go back to using wing cannons as standard?) The 801 would seem a bad fit for the 109. Heavy, draggy, and fuel hungry. Maybe use Jumo powered 109s on the Eastern front where altitude performance wasn't as critical? (maybe have more precedent for MW/50 systems being developed for the 211?) Somewhat like the Avia S-199 but less of a hack job with properly mated prop and reduction gearing, and preferably J/N/P models rather than F.



The Avia S-199 have had plenty of aerodynamic issues to be any better than, say, Spitfire V. Under wing cannons, fixed tailwheel, bulges of the MG 131s, bulges at the wing to accommodate bigger tyres of the main U/C. Unlike the late 109 from where it emerged, it did not have the DB 605 to cover for those aerodynamic problems. I'm not sure that Germans themselves would make it perform any better than the Czechs. 



> Plus, relegating more of those 'lesser' 109s to the Eastern front and diverting even more 190s to the ETO might have been a worthwhile trade-off. (especially with the potential potency of DB powered 190 variants)
> 
> Bombers/heavy/night fighters with more 801s, 190s with more 605s (and 603s), and supplemental 109s with 211s might have made some sense. (again, if 109s couldn't be phased out entirely)



The Luftwaffe is outnumbered by 1943 (even earlier). So the aircraft that get to the frontline need to perform better than opposition. I'm afraid the Bf 109 with Jumo 211 will not cut it even on the Eastern front. 



> There's also the He-100 to consider, which might have made an even better fit for the DB-605 (or 601) but was also a tighter/limited design. The 190 is bigger and heavier, but remarkably flexible in overall design, more space for expansion and weight gain, fuel, armament, and a variety of engines. (plus it was in development at the same time as the He-100, so unless the He-100 was actually easier to manufacture, ramping up/second sourcing 190 production would seem most useful)



The Fw 190 was already produced in several factories. Indeed it is flexible, has other strong points, just need a good piece of engine from late 1943 on to remain competitive against Western opposition.



> Again, this seems a bit like the Hurricane production situation and only relevant if it was impossible to replace 109 volume production with other types. (albeit a much more limited argument due to the scarcity of ASM engines)
> Keeping 109s competitive in the ETO/MTO is only a problem if there's no alternative to displace them entirely ... at least outside of the Eastern front.



I'd displace the Bf 109 with a jet. Simple 1-engined job, with 2 cannons.


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## Shortround6 (Mar 18, 2015)

tomo pauk said:


> I'd displace the Bf 109 with a jet. Simple 1-engined job, with 2 cannons.



Trouble with that is you don't have enough power with only one engine. Speed will be in the 450-500mph range (but not likely to be over) but armament will be light. 2 cannon is doable but ammo capacity? Fuel and endurance will be pretty poor. 
HE 162 _may_ be as good as it got. The single engine Yak and LA fighters/prototypes using Jumo or Jumo derived engines certainly had problems with endurance.


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## tomo pauk (Mar 18, 2015)

Granted, an early single jet engine can't buy you everything. What it might buy in second half of 1944/early 1945 is the performance parity (or a bit over parity) vs. Western top performers, and considerable performance advantage vs. Soviet stuff. 450-500 mph is a better offer than 420-450 mph that can be expected by late Bf 109s (DB-605AS up until 605L) .


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## Shortround6 (Mar 18, 2015)

450-500mph potential for 30 minutes or 420-440mph potential for 60 minutes? 

Not that either plane could really keep up those speeds for anywhere near the full time/s.

The Jet sorties have to be very carefully timed. And like the 262s, getting caught at low altitude/low speed is not good.


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## tomo pauk (Mar 18, 2015)

The late Bf-109 will not do 420-450 for 60 min. Five-ten minutes?
Any aircraft caught low slow is asking to get bounced.


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## Shortround6 (Mar 18, 2015)

I did say "potential" to show that the plane wasn't doing it all the time. 
The early jets had horrible acceleration. That miss-match between exhaust gas speed and aircraft speed. It just wasn't the time for the engine for spool up that was a problem. Think of jets as having (sort of) fixed pitch props and the pitch is set for 600mph+ . They aren't bad at 450-500mph but at 200-250mph they are terrible (let alone take-off). Turbo-fans bring the exhaust gas speed and aircraft speeds closer into agreement. 

Why did 262s need escorts when they were in the landing circuit? a single engine plane using the same engine won't be any better.


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## tomo pauk (Mar 18, 2015)

The Fw-190s and Bf-109s needed escort all the time once the Merlin Mustangs or P-47s were around, not just when on landing approach. Having a 1-engined jet fighter means the LW pilot has either parity or upper hand vs. those during a good deal of it's flight; the pilot of the Fw-190 or Bf 109 can hardly expect that.


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## Shortround6 (Mar 18, 2015)

The pilot of the one engine jet has parity or upper hand for 20-30 minutes after take-off. Then he is toast. You have to plan the take-offs and intercepts very carefully. Not as bad as a Me 163  but there is darn little loiter time. 

Trouble is the performance numbers are all over the map. From Wiki for Yak 15

Maximum speed: 786 km/h (488 mph; 424 kn)
Combat range: 510 km (317 mi; 275 nmi)
Service ceiling: 12,000 m (39,370 ft)
Rate of climb: 21.6 m/s (4,250 ft/min)
Gross weight: 2,638 kg (5,816 lb)
Fuel capacity: 590 kg (1,300 lb)

For Yak-17:
Maximum speed: 748 km/h (468 mph)
Range: 395 km (247 miles)
Service ceiling: 12,750 m (41,820 ft)
Rate of climb: 12 m/s (2362 ft/min)
Loaded weight: 2,890 kg (6,358 lb)
"redesign of the fuel tanks and reduced their capacity to just 680 liters (150 gallons). This necessitated the addition of two 200 liter (44 gallon) jettisonable tanks,"

Yak-19





First flight	8 January 1947
Loaded weight: 3,050 kg (6,724 lb)
Max. takeoff weight: 3400kg ((7495lb)
Maximum speed: 907 km/h at 5,250 m, 875 km/h at sea level (490 knots, 563 mph at 17,225 ft; 472 knots, 543 mph at sea level)
Range: 550 km (340 miles)
Ferry range: 895 km with drop tanks (555 miles)
Service ceiling: 12,100 m (39,700 ft)
Rate of climb: 20.8 m/s (4,094 ft/min)

Early jets do NOT throttle down well. They can use 90% of the fuel for a lot less than 90% of the power. 

Of course single engine planes using those early jets with their noted lack of reliability could make things rather interesting for the pilots. Engine flames out and the pilot has what for choices?


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## kool kitty89 (Mar 19, 2015)

tomo pauk said:


> Not that a good fit before late 1943, until the DB 605A was allowed for 2800 rpm and 1.42 ata. The 605AM is also not available before 1944. I'd still prefer the DB 603 and Jumo 213 for West-bound Fw-190s, indeed the BMW 801 seem like the best bet for fighter-bomber versions of the Fw-190. Also for fighters for Eastern front, with it's good/excellent power under 5-6 km alt.


So, prior to that, a DB-605 (or possibly 601) powered 190 variants would have mostly been good for specialized tasks where long endurance/range is required, possibly with reduced armament to save further weight. That and high altitude performance with the 605-AS. (even with the DB-605A, the reduced weight and drag might make it better at high altitude work, including escorting heavier interceptors -possibly better at that job than similarly engined 109s, and 2x wing root synched MG-151/20s is better than 1x 151/20 and 2x 131s)



> Methinks it is a question of timing. The BMW 801D is IMO the best engine for the Fw-190 until the DB 603A is available reliable (late 1943?). The Jumo 213A is there also by late 1943/early 1944 - that means the Jumo 211 is slowly phased out from production/use, and the promising 'fighter version', the 211R will not be produced. The 211J/N/P in the Bf 109 will cut it's performance. I'd push 213s in the Fw-190 (along with DB 603s), so the Bf-109 can keep the Db 605s.



It'd be somewhat like a hypothetical R-2600 or perhaps single-stage R-2800 (or maybe Hercules) powered Mustang vs Merlin Mustang or hypothetical Merlin XX Mustang. (Allison Mustang might be more akin to Jumo-211 powered 190? -if performance was anything close to the Allison mustang, that might actually be useful too -if there's surplus airframes to 'waste' on a lesser engine)

Jumo 213 and DB-603 are obviously good fits for the 190 as it is, though, less speculation there. (those Jumo 211s might be worthwhile diverted to Fw-187 variants; 605s would be better, but 211s probably still would have done acceptably well -particularly compared to mating them to the 109, leave the late-war 801s to bombers, attack planes, fighter-bombers, and night fighters)


There's also the pilot factor: is it worth risking valuable pilots in inferior (if adequate) aircraft? (or logistically, are there ENOUGH pilots of any type to risk that?) But then, that would also be an argument in favor of the Fw-187. (per pilot effectiveness, not pound for pound manufacturing cost effectiveness)




> The Fw 190 was already produced in several factories. Indeed it is flexible, has other strong points, just need a good piece of engine from late 1943 on to remain competitive against Western opposition.


The question was more whether they could have ramped up production even further with the Fw 190 variants becoming the primary/solitary single engine fighter in production.




> I'd displace the Bf 109 with a jet. Simple 1-engined job, with 2 cannons.


So ... the He-162 but earlier? The Jumo 004B might not have been reliable enough for that. Inability to limp home on one engine means almost certain loss of the aircraft in the case of engine failure, especially at low speed/altitude.

Even with hypothetical earlier Jet engine production (I argued more conservative development of Ohain's initial designs might have managed that in the axial vs centrifugal jet thread) or even maturation of more foolproof designs earlier, or better all around engines (like the HeS-30 -109-006- reaching production), twin engine designs would still make more sense. (as interceptors or recon aircraft -maybe attack but jets are horribly inefficient at low altitude, and purpose-built high alt level bomber would make more sense) Twin-jet trainers would have been significant too. (if Heinkel had managed non-combat-ready advanced trainers in the vein of the role the P-59 played with the USAAF, that itself would have been very worthwhile)

That and a single engine jet wouldn't directly displace the 109 either. The 190 might be able to fill out all the roles the 109 played, a high performance twin like the Fw-187 could fill in some gaps too, but a jet is rather different all around. (heavy prop twin pilots might transition more easily to twin jets too)

And really, even with the He-162, the LW would probably have been better off foregoing the light fighter program entirely and just pushing out more Me 262s. (BMW-003 powered 262s would have a number of advantages over both the He-162 and 004B powered 262) I might make an exception for something closer to the Vampire ... in both a relatively conservative and foolproof engine as the Goblin that was also powerful enough to be used by a reasonably sized single engine fighter. (the pod+boom design also fit the exact same reasoning Heinkel went with nacelles -short intake and exhaust)

Though that said, having Messerschmitt scale back or discontinue 109 production in favor of ramping up Me-262 production could have been very useful as well. The design fit well with all of the 'class I' jet engines, 003, 004, and especially Heinkel's 006 -but even the 001 (HeS 8 ) likely would have fit better on the Me-262. The He-280's empty, engineless weight was very close to the 262's from the figure's I've seen. (Had Heinkel persued the bulkier earlier designs of Ohain -that seemed to be progressing much more smoothly than the HeS-8- the Me-262 might have had more trouble mounting those without another redesign to the wing, so Heinkel designing a more optimal aircraft with that in mind might have been better)

Sort of like the Fw-190 actually ... a large design that could work well enough weighed down with heavy engines, capacity for tons of fuel, and a heavy armament, but was also fairly flexible. (including potential lighter configurations)


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## Shortround6 (Mar 19, 2015)

The early jets simply were not powerful enough on their own as singles. Which is why just about everybody initially designed twins. You can cut the armament in half but you can't cut the pilot, armor, radio and cockpit in half so the single engine plane winds up with a lower power to weight ratio. That leaves cutting fuel below 1/2 and the resulting very short endurance.
When jet designs started power was around 12-1600lbs thrust. Even one year could bring big changes and with start of design to flight taking around 3 years many programs over lapped a quicker later program could over take an earlier program. With 25-3000lb thrust engines a single engine plane.looked a lot.better.


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## tomo pauk (Mar 19, 2015)

kool kitty89 said:


> So, prior to that, a DB-605 (or possibly 601) powered 190 variants would have mostly been good for specialized tasks where long endurance/range is required, possibly with reduced armament to save further weight. That and high altitude performance with the 605-AS. (even with the DB-605A, the reduced weight and drag might make it better at high altitude work, including escorting heavier interceptors -possibly better at that job than similarly engined 109s, and 2x wing root synched MG-151/20s is better than 1x 151/20 and 2x 131s)



The Fw 190 with DB 605A would be similar to the Re.2005? Good for Eastern Front, not that good for MTO/ETO? The variant with 605AS/ASM does ring a bell, but again the DB 603A is significantly earlier.



> It'd be somewhat like a hypothetical R-2600 or perhaps single-stage R-2800 (or maybe Hercules) powered Mustang vs Merlin Mustang or hypothetical Merlin XX Mustang. (Allison Mustang might be more akin to Jumo-211 powered 190? -if performance was anything close to the Allison mustang, that might actually be useful too -if there's surplus airframes to 'waste' on a lesser engine)



The 1-stage R-2600 was not much of a 'fighter's engine' when better ones are available - at 20000 ft it gives 1100 HP, it is bulkier than the BMW 801 and Hercules, the exhaust system robs much of exhaust thrust. The 1-stage R-2800 B will make ~1280 HP at 20K, the fully rated BMW 801D is at ~1350 HP there, it is as streamlined as it goes and has the exemplary exhaust system; the air intake is restricted, though.
Allison Mustang has the low-drag wing and 'clever' radiator, not sure that Jumo 211-powered Fw 190 would be worth it once there are better engines around.


> The question was more whether they could have ramped up production even further with the Fw 190 variants becoming the primary/solitary single engine fighter in production.
> ...



Fighter production was probably as ramped up as possible by 1944, what was needed was quality (ie. performance advantage vs. Allies), night fighters, better bombers. With such a flow of fighters, the trained pilots and fuel are bottlenecks; that was felt before, but in 1944 became acute.


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## dedalos (Mar 19, 2015)

there can be no thought about using the db605A in the fw 190. The resulting airplane would be a dog with terrible power to weight ratio.
If germany had surplus db605s should use them to build one of the three series 5 italian fighters. All three of them made better use of the db 605 than the 109 did
With MW50 would absolutely superior to the fw 190A as well


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## kool kitty89 (Mar 19, 2015)

Shortround6 said:


> The early jets simply were not powerful enough on their own as singles. Which is why just about everybody initially designed twins. You can cut the armament in half but you can't cut the pilot, armor, radio and cockpit in half so the single engine plane winds up with a lower power to weight ratio. That leaves cutting fuel below 1/2 and the resulting very short endurance.
> When jet designs started power was around 12-1600lbs thrust. Even one year could bring big changes and with start of design to flight taking around 3 years many programs over lapped a quicker later program could over take an earlier program. With 25-3000lb thrust engines a single engine plane.looked a lot.better.


Or go back and forth like the Goblin and Whittle designs did. (Halford's work started later but progressed much faster than Whittle's at powerjets -or Rover- but Rolls Royce's involvement accelerated things considerably; I've wondered how things might have progressed if the Vampire+Goblin had been giving priority by the air ministry over the Meteor+W.2 ... or the goblin in general since the Meteor itself adapted well enough to mounting goblins) The Whittel based Rolls Royce designs ended up developing out much better post-war (Derwent V/8 better than Goblin and Nene/Tay better than Ghost at least performance to size/weight wise -maybe not manufacturing cost and maintenance)

That said, the Goblin's conservative design actually reminds me of Jumo's design philosophy with the exception of being a concervative centrifugal vs axial compressed design. (would have been interesting if Junkers/Jumo had developed a centrifugal design in parallel with the 004, especially if keeping the combustion/turbine section as similar as possible -trade weight and length for diameter and faster spool up times with the lighter compressor section, possibly fewer harmonic/vibration problems too)




tomo pauk said:


> The Fw 190 with DB 605A would be similar to the Re.2005? Good for Eastern Front, not that good for MTO/ETO? The variant with 605AS/ASM does ring a bell, but again the DB 603A is significantly earlier.


Perhaps shifting manufacturing emphais from 605 to 603 earlier on (with the Fw-190 in mind) would have made more sense then?

The best place for 605s in general would seem to be something like the He-100 (if it coped well with ever expanding weight/bulk the 109 had to), the Fw-187, and then maybe some of the itialian designs or a lighter weight Fw-190 derivative. The aging Bf-109 airframe, while obviously able to be pushed out in huge volumes, seems a good bit less than the ideal option in terms of quality or quantity. (in terms of sheer speed/climb, versatility, and armament potential, a high performance twin seems like it might have made a lot more sense as both a day and night fighter ... plus good enough to perform reasonably well with surplus Jumo-211s when needed)



> Fighter production was probably as ramped up as possible by 1944, what was needed was quality (ie. performance advantage vs. Allies), night fighters, better bombers. With such a flow of fighters, the trained pilots and fuel are bottlenecks; that was felt before, but in 1944 became acute.


Yes, I meant more in terms of re-allocating manufacturing resources earlier on to allow the 109 to be phased out while minimizing loss in capacity while transitioning to newer types. (if it was between re-tooling for the He-100 or pumping out more Fw-190 airframes across the board, the latter seems a more conservative bet ... He-100 would be a better direct replacement for the small fighter/interceptor role, though, and the wing root gun placement apparently would have allowed MG-151s to be fitted in place of the MG-17s, similar to the Fw-190 A1 vs A2 plus the engine cannon, and no cowl guns hindering aerodynamics) The Fw-187 and He-100 were both in development early enough to be seriously considered for war-time use ... at least for a more heavily strategically minded standpoint. (the tunnel vision surrounding a short, tactical power emphasized war obviously limited a lot of things in the longer term, yet that didn't stop them from still investing in numerous other follow-on developments)

If nothing else, it might have needed a larger wing to cope with weight increases in later models, though.


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## tomo pauk (Mar 20, 2015)

kool kitty89 said:


> ...
> Perhaps shifting manufacturing emphais from 605 to 603 earlier on (with the Fw-190 in mind) would have made more sense then?



Forgetting the Jumo 222 in a timely manner would've helped both with DB 603 (so it can be produced in the Ostmark factory earlier) and Jumo 213 (more people resources for it in development stage). A simple re-shuffle of produced engines from second half of 1943 on - DB 603 for Fw-190, BMW 801 for Me-410 the like - would not harm the twins, but it would bring necessary boost in hi-alt performance for the Fw-190 for the ETO. The over-boosted BMW 801 in the 190 would be still plenty enough for the Eastern Front.

I won't comment on the Bf-109, He-100, jets, since we're veered way of topic


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## Denniss (Mar 20, 2015)

Keep the Fw 190 as-is but as soon as DB 603 and Jumo 213 become available in a reliable from switch Fw 190 fighters to use these two engines. Keep the 801-engined version as ground attack F/G.
Bombers historically powered by DB 603/Jumo 213 may switch to BMW 801 (or even DB 606/610) or keep last generation Jumo 211.

Still a mystery to be why BMW was not able to generate more power out of the 801D-2, it had just a tad more power power per liter than the DB 605 which didn't require expensive/exotic C3 fuel (comparison made without substracting ~70 PS required by fan).


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## tomo pauk (Mar 20, 2015)

The 801D was turning 100 rpm less than DB 605 (when both are fully rated), that's enough difference in rpm to be worthwhile. 
BMW 801D was, in power per liter, very much comparable with Allied big radials. Without subtracting the power for the fan, it maxed at 1800 PS in low gear and 1490 PS in high gear. Once the over-boost was allowed, thus fully taking advantage of improving C3 fuel, the power at low and mid altitudes was excellent - ~ 1950 down low, ~1650 HP at medium alt for service machines. It was flight tested for even greater power in low gear. 
It's power at altitude was decent, only comparable radial that was better used a 2-stage supercharger.

What hampered the real life performance in a Fw-190 was the layout of air intake: the internal type was too restricted/squished (messes with ram effect; not sure how much the turbulent air due to the fan prop interfered), the external type was an after-thought - good for hi-alt, too draggy otherwise.


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## Shortround6 (Mar 20, 2015)

Air cooled engines rarely, if ever, matched liquid cooled engines on a power per unit of displacement basis. The best air-cooled aircraft engine for power per liter during WW II was the "C" series P&W R-2800 and it required all new cylinders/cylinder heads, pistons, rods, crankcase, crankshaft, a turbo, an inter-cooler, lots of water injection and 100/130 fuel and/or water injection and 100/150 fuel to hit 61hp per liter. 

I would note that on a per liter basis a Merlin could beat this using 100/130 fuel, 18lbs of boost, NO water injection. In fact some Merlins could come *very* close (60 hp per liter) using a single stage supercharger, no inter-cooler, 18lbs boost (about 66in), no water injection and 100/130 fuel. The Merlin 32 might even beat it.


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## kool kitty89 (Mar 21, 2015)

tomo pauk said:


> Forgetting the Jumo 222 in a timely manner would've helped both with DB 603 (so it can be produced in the Ostmark factory earlier) and Jumo 213 (more people resources for it in development stage). A simple re-shuffle of produced engines from second half of 1943 on - DB 603 for Fw-190, BMW 801 for Me-410 the like - would not harm the twins, but it would bring necessary boost in hi-alt performance for the Fw-190 for the ETO. The over-boosted BMW 801 in the 190 would be still plenty enough for the Eastern Front.


The BMW 802 seems like a more practical and straightforward design than the Jumo 222 as well, but focusing on improving the 801 (particularly the intake manifold and supercharger ducting) would have likely been more worthwhile. 



tomo pauk said:


> It's power at altitude was decent, only comparable radial that was better used a 2-stage supercharger.


Didn't some of the Japanese radials manage similar/better with single stage superchargers?



> What hampered the real life performance in a Fw-190 was the layout of air intake: the internal type was too restricted/squished (messes with ram effect; not sure how much the turbulent air due to the fan prop interfered), the external type was an after-thought - good for hi-alt, too draggy otherwise.


Weren't some of the major changes to the 802's induction system designed to resolve those problems? (and potentially more worthwhile applied directly to 801 development)



Shortround6 said:


> I would note that on a per liter basis a Merlin could beat this using 100/130 fuel, 18lbs of boost, NO water injection. In fact some Merlins could come *very* close (60 hp per liter) using a single stage supercharger, no inter-cooler, 18lbs boost (about 66in), no water injection and 100/130 fuel. The Merlin 32 might even beat it.


The single stage Allisons were also breaking 61 hp/L when overboosted to 66" ... albeit near sea level.




Denniss said:


> Keep the Fw 190 as-is but as soon as DB 603 and Jumo 213 become available in a reliable from switch Fw 190 fighters to use these two engines. Keep the 801-engined version as ground attack F/G.
> Bombers historically powered by DB 603/Jumo 213 may switch to BMW 801 (or even DB 606/610) or keep last generation Jumo 211.


Probably better to forgo the coupled V-12s entirely ... don't waste 601/605 production/development resources on those.

And if you're considering sticking with the late Jumo 211s over those others, considering 605s would be worth noting too.


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## tomo pauk (Mar 22, 2015)

kool kitty89 said:


> The BMW 802 seems like a more practical and straightforward design than the Jumo 222 as well, but focusing on improving the 801 (particularly the intake manifold and supercharger ducting) would have likely been more worthwhile.



The BMW 801E wasn't produced because producing it would've mean most of the tooling that produces BMW 801D cannot be used, so methinks that 802 would've never see production, too. Improved 'internal aerodynamics' of the 801E was used on the 801S, along with some other tweaks that brought considerable power gains, but too late to matter. The 801F was to include a streamlined outer intake.
At any rate, I'd try to perfect the 801D.



> Didn't some of the Japanese radials manage similar/better with single stage superchargers?



In 1945, the working Homare was better, looks like it was even better than the contemporary 801S. US report on the Homare: link.



> Weren't some of the major changes to the 802's induction system designed to resolve those problems? (and potentially more worthwhile applied directly to 801 development)



The 802 was to feature either 1-stage 3-speed S/C or a 2-stage S/C (each stage with independent 2 speed gearing). The after-cooler was also to be installed (for 2-stage version only?), not inter-cooler like at 2-stage R-2800. Oil coolers were to be installed behind cylinders.
The 2-stage S/C would come in handy for the 801D, but, please, with simple 2-speed gearing


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## dedalos (Mar 22, 2015)

.


In 1945, the working Homare was better, looks like it was even better than the contemporary 801S. US report on the Homare: link.



.The working Homare, was not just better,it was much better than the BMW 801. It produced 2000hp on low grade fuel,was smaller in frontal surface and was much lighter than the 801.
No surprise that the ki 84 was probably among the Top dogfighters of the war
Perhaps,better technology Exchange would have helped the 190 alot


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## wiking85 (Mar 22, 2015)

dedalos said:


> .
> 
> 
> In 1945, the working Homare was better, looks like it was even better than the contemporary 801S. US report on the Homare: link.
> ...



I thought the Homare used 90 octane fuel?


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## tomo pauk (Mar 22, 2015)

Problem with a working Homare is that is way too late for LW needs - the Japanese were still having reliability issues in 1945 with it. 
What Germany could use is the Farman-style 2-stage supercharger that was featured in Flight magazine in 1938 (or 1939?), or maybe RR Merlin 61 type 2-stage supercharger that was published in Flight magazine in December 1942. The Germans were probably aware of P&W developments of 2-stage superchargers for radial engines before Pearl Harbour, as well about advantages of Bristol-engined aircraft with 2-stage engines that claimed several world records in altitude in late 1930s.


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## kool kitty89 (Mar 22, 2015)

tomo pauk said:


> In 1945, the working Homare was better, looks like it was even better than the contemporary 801S. US report on the Homare: link.


I was also thinking the Ha109 and some models of Kasei were on a similar (or slightly better) level of altitude performance than the 801. (or at least relative to size, weight, and/or displacement)



> The 802 was to feature either 1-stage 3-speed S/C or a 2-stage S/C (each stage with independent 2 speed gearing). The after-cooler was also to be installed (for 2-stage version only?), not inter-cooler like at 2-stage R-2800. Oil coolers were to be installed behind cylinders.
> The 2-stage S/C would come in handy for the 801D, but, please, with simple 2-speed gearing


Or a larger (or faster) single stage unit with aftercooler, or single speed integral stage + 2 speed+neutral aux stage like American engines adopted. (and in any case, better ducting arrangement, minimizing intake losses and allowing ram)






tomo pauk said:


> Problem with a working Homare is that is way too late for LW needs - the Japanese were still having reliability issues in 1945 with it.
> What Germany could use is the Farman-style 2-stage supercharger that was featured in Flight magazine in 1938 (or 1939?), or maybe RR Merlin 61 type 2-stage supercharger that was published in Flight magazine in December 1942. The Germans were probably aware of P&W developments of 2-stage superchargers for radial engines before Pearl Harbour, as well about advantages of Bristol-engined aircraft with 2-stage engines that claimed several world records in altitude in late 1930s.


Not to mention the communication and translation issues (aside from political ones) complicating exchange. It was bad enough trying to get domestic German firms to collaborate or share information (and ministry attempts at such cooperation were also harmed by other ministry meddling and political posturing ... ) You still had independent firms competing with each other for projects and retaining considerable trade secrets without much consideration for cross-licensing. (that goes for piston and jet engines alike)

I'd be surprised if those issues weren't part of the reasons behind the problems with the Japanese built DB engines. (though I've also wondered if the Jumo 211 might have been more fool proof to license build ... or if they'd continued domestic Japanese development of inlines earlier on moving from the old BMW based Kawasaki Ha-9 somewhat like Mikulin did)


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## Koopernic (Mar 22, 2015)

One huge problem the Germans faced was their lower octane fuels.

87 octane fuel has a PN performance number of only 62.5%, so for the same swept volume the Germans in theory could get only 62.5% the power of an Allied engine running on 100 octane. 

What they did was use an unusual form of construction on the DB601 such that the DB601 had slightly less weight and frontal area as the single stage Merlins. The Merlin had a swept volume of 27L while the DB601 had a swept volume of 33.93L which is 26% greater. They lost a lot of this advantage with lower RPM but not all of it and their RPM increased from 2500 to 2800 between DB601A to DB601E (compared to 3000 for Merlin)

They then added multi point fuel injection. This meant the last component of end gas during the exhaust stroke could be scavenged by using either blower pressure and inlet/outlet tunning (known as extractors by hot roders) perhaps 10% more fresh air inducted without fear of loosing air/fuel out of the exhaust.

This perhaps also allowed a higher compression ratio (more like 7:1 versus the Merlin 6:1) which allowed more power and efficiency since residual end gases can cause preignition.

Even with this effort a 87 octane Merlin could produce 1030hp wheras the DB601A little more and the more advanced DB601AA maybe, just maybe 100hp more (1175 ps say 1150hp) The reality is that the Merlin was on 100 octane by the time war broke out and producing 1310hp, then soon enough by 1942 1500 and then 1620. The DB605 never reached these power levels till 1944 and the DB601E never did.

The DB601E introduced a sharp valve overlap that allowed even more scavenging and did so by having variable length inlet ducts to 'tune' the manifolds at high RPM.

A crical year was 1942. The Merlin added power mainly by improved fuels getting to 1620hp on the Merlin 25 single stage. However the Merlin 61 added an two stage supercharger to increase critical altitude and an intercooler to allow slightly higher supercharger compression ratios at high altitude (but also slightly a low altitudes).

The DB601 increased piston swept volume while retaining DB601 key dimensions but increasing weight from 580kg to 720kg (about same as Merlin 61 two stage) but the result is that in 1942 Me 109G1 with 1300 hp DB605A are facing 1560hp Spitfire IX with Merlin 61 (and likely a lot more jet thrust).

The single stage DB engines did quite well on a single stage because by their design they did not use the supercharger to 'overboost' the engine to gain power but mainly to altitude compensate. Hence the DB605AS which increased the volume of air that could be compressed by being bigger rather than focusing on pressure ratios.

However it is possible to imagine that Daimler Benz instead stayed with the DB601 but added an intercooler and maybe a two stage supercharger to gain power as the Merlin did. Afterall Junkers added a intercooler on the Jumo 211J. Perhaps the Me 109 couldn't have coped with a longer engine and intercooler might require. Without an intercooler a two stage DB601 would surely need water injection or C3 fuel. (Note 1942 C3 fuel was much lower grade than allied 100/130)

A two stage DB605L did not appear on production till 1945, it used C3 and MW50 to achieve critical altitudes of nearly 9.7km but did not have an intercooler.

Earlier attempts were the DB627, a DB601 with two stages. I think the concept was sound but it probably couldn't fit into the Me 109 since the first stage supercharger was coaxial with the gearbox.


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## tomo pauk (Mar 23, 2015)

Some comments 



Koopernic said:


> ...
> They then added multi point fuel injection. This meant the last component of end gas during the exhaust stroke could be scavenged by using either blower pressure and inlet/outlet tunning (known as extractors by hot roders) perhaps 10% more fresh air inducted without fear of loosing air/fuel out of the exhaust.
> 
> This perhaps also allowed a higher compression ratio (more like 7:1 versus the Merlin 6:1) which allowed more power and efficiency since residual end gases can cause preignition.



The higher compression will indeed allow for more power if the engine is not using any form of 'forced induction'. However, any piston engine (for aircraft) worth it's name used it. Higher compression is then more of a liability, than the advantage, since greater compression means less boost can be used. 



> Even with this effort a 87 octane Merlin could produce 1030hp wheras the DB601A little more and the more advanced DB601AA maybe, just maybe 100hp more (1175 ps say 1150hp) The reality is that the Merlin was on 100 octane by the time war broke out and producing 1310hp, then soon enough by 1942 1500 and then 1620. The DB605 never reached these power levels till 1944 and the DB601E never did.



The DB-601Aa (not sure the AA was ever produced?) was the version a bit more power down low (where the S/C will eat less power), and a bit less above 4 km. The 1150 HP power was at low altitude, rated powers at altitude were 1020 for the 601A at 4-4.5 km and 1100 HP for the 601Aa (but at lower alt, up to 3.7 km). 
A Merlin was capable of 1130 HP at 5000 ft on 87 oct (5.75 psig) - the Merlin X in low gear.



> A crical year was 1942. The Merlin added power mainly by improved fuels getting to 1620hp on the Merlin 25 single stage. However the Merlin 61 added an two stage supercharger to increase critical altitude and an intercooler to allow slightly higher supercharger compression ratios at high altitude (but also slightly a low altitudes).



Merlin 25 was produced in 1943, not in 1942, per Lumsden. Though, he lists the Mk.24 as built from 1944 on.
Merlin 61s pressure ratios were in the ballpark whether in low gear or in high gear (and while at same rpm). The Merlin 24 and 25 will make 1620 HP at ~2400-2500 ft, the Merlin 61 will do 1530 HP at 13000 ft (both for max power at low gear).



> The DB601 increased piston swept volume while retaining DB601 key dimensions but increasing weight from 580kg to 720kg (about same as Merlin 61 two stage) but the result is that in 1942 Me 109G1 with 1300 hp DB605A are facing 1560hp Spitfire IX with Merlin 61 (and likely a lot more jet thrust).



The contest, if we look at 1:1 situation for 109 and Spit, was rather even. Bf-109G1/G2 were much smaller than Spit IX, carried half of weapon weight, 109s were not yet cluttered by fixed tail wheel, MG and wheel bulges. Spitfire should handily out climb it at most of altitudes, however, wile carrying a heavier battery.



> The single stage DB engines did quite well on a single stage because by their design they did not use the supercharger to 'overboost' the engine to gain power but mainly to altitude compensate. Hence the DB605AS which increased the volume of air that could be compressed by being bigger rather than focusing on pressure ratios.



The single stage DB engines did quite well because they were big, turning good RPM, and they did have decent superchargers. They used S/C for power (1.4 ata is not 1 ata; S/C of DB 605 was easily making 1.7 ata), overboost was out of question if hi-oct fuel was not there, and/or MW 50. 
As with many engines, the DB-601/605 engines did quite well when an aircraft was not too big/heavy, talk Bf-109 or MC-202/205. However, by late 1943, even the fully rated DB 605A have had problems to propel through air (with a really high speed RoC) a fighter with heavy firepower and of not so humble dimensions.


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## wiking85 (Mar 23, 2015)

Koopernic said:


> One huge problem the Germans faced was their lower octane fuels.
> 
> 87 octane fuel has a PN performance number of only 62.5%, so for the same swept volume the Germans in theory could get only 62.5% the power of an Allied engine running on 100 octane.
> 
> ...



So what was the potential of the DB605 with lots of C3 fuel available? Or the Jumo 211?


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## tomo pauk (Mar 23, 2015)

Seems it was 1700+ HP at low alt, 1640 PS at 4 km, for DB 605 with 'normal' S/C; that is at 1.7 ata. The 605D was making 1.8 ata under FTH, at low level it was 1800+ PS. For the C3 with MW 50, add another 100-200 PS.

BTW:



> Earlier attempts were the DB627, a DB601 with two stages. I think the concept was sound but it probably couldn't fit into the Me 109 since the first stage supercharger was coaxial with the gearbox.



The attempts on DB 601 with 2-stage S/C were named DB 601C and 601D, and I'd appreciate any good data on those, other than it's written by Von Ghersdorf et al. 
The DB 627 was the DB 603 with 2 superchargers - one supercharger at each side. S/C installed on the left side fed the S/C installed on the right side, after that the compressed air went through the after-cooler and entered intake manifold.

edit: very worth reading (pics tables): link


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## Shortround6 (Mar 23, 2015)

It is not just one thing. 

87 octane had a PN of 68.29 not 62.5 PN.

It depends on the year. Early C-3 fuel was not the same as late C3 fuel. 

The DB 605 had problems with the pistons which limited boost for a while from 1.42 to 1.4 Ata ( Not sure if better fuel would that problem or not) 

The DB 605 could go to 1800hp with the better fuel, but like the Allison and Merlin the supercharger limited the altitudes at which that power level was available. 

As in: 
DB 605A was good for 1355PS at 5700 meters.
DB 605AM was good for 1700PS at 4000 meters.
DB 605AS was good for 1200PS at 8000 meters.
DB 605ASM was good for 1500PS at 6400 meters.
DB 605DB was good for 1600PS at 6000 meters.
DB 605DC was good for 1800PS at 4900 meters..

The Big supercharger from the 603 simply wasn't going to deliver enough air to make 1800hp at above 4900 meters no matter what fuel you put in it. Better fuel and/or MW50 allowed higher powers below the critical altitudes. 

There are a slew of different Jumo 211s and even on the later ones (with higher rpm and stronger crankshafts,etc) you are going to be limited by the supercharger and engine strength. A single stage Griffon, 36.7 liters went about 812 KG. Which is about 90kg more than the 211F, a 33 liter engine.


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## tomo pauk (Mar 23, 2015)

> The DB 605 had problems with the pistons which limited boost for a while from 1.42 to 1.4 Ata ( Not sure if better fuel would that problem or not)



Only 1.30 ata was allowed for more than a year, also max RPM was down to 2600 instead of 2800. 



kool kitty89 said:


> I was also thinking the Ha109 and some models of Kasei were on a similar (or slightly better) level of altitude performance than the 801. (or at least relative to size, weight, and/or displacement)



The Ha-109 has several stong points. It was light compact, the nominal power was rather good on 92 oct fuel: 1220 CV at 5200 m, at +200 mm Hg boost and 2600 rpm (how much power at more aggressive settings?), take off power was also decent (1500 CV on 2650 rpm and +300 mm Hg);probably a better layout of air intake. Shortcomings vs. the fully rated BMW 801D would be overall power at short term aggressive settings, less refined exhaust system. Actually, the DB 605A should provide more power overall than the Ha-109, or at least in the ballpark, with less drag and better exhaust thrust. 
Kasei was of wider diameter, that spurred Mitsubishi for extension shaft in the Raiden to get some streamlining. The power at altitude for late war engines was excellent, a bit over what BMW 801D was making, but greater diameter would've eat that power, and maybe then some.



> <about possible improvements for the BMW 801>Or a larger (or faster) single stage unit with aftercooler, or single speed integral stage + 2 speed+neutral aux stage like American engines adopted. (and in any case, better ducting arrangement, minimizing intake losses and allowing ram)



The low-alt power was good/great, so maybe going for an increased speed of the S/C would be the most expedient job? Loose 150-200 PS down low, gain 100-150 PS high up?
I cant be bothered to calculate the tip speed of historic S/C of the 801D, however, it was a long day


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## Koopernic (Mar 24, 2015)

wiking85 said:


> So what was the potential of the DB605 with lots of C3 fuel available? Or the Jumo 211?



As Shortround said, it depends on the C3 fuel.

My estimate is as follows
The BMW801 went from 1560hp to 1700hp when early C3 was allowed using a combination of slightly higher compression ratio and boost. Boost went from 1.3 ata to 1.42 ata. (there was a short period of 1.38 ata boost in between)

So you could say B4 to early C3 = 10%
The Jumo 213A was a 1750hp bomber engine, however C3 powered version, the Jumo 213b was also offered, it was nominally 2000hp. It also offered a motor canon.

The DB605 was a 1750hp bomber engine, the G version used C3 and produced 1900hp, it featured an improved supercharger.

So you could say B4 to Early C3 about 10% (as shown on the DB603G) to 14% (as shown on the Jumo 213A->213B

As C3 improved the BMW801 was allowed to increase boost from 1.42 to 1.68 and reach over 1900hp. This is about 20%.
B4->Late C3 about 20%.

A modification, still at the 1.68ATA limit involved running a fuel pipe to the air inlet ahead of the supercharger and injecting the C3 fuel there, this increased power to 2050. It precooled the air and contracted it so more could be forced in, this I think is one of the effects of the aromatic content that produces a high PN rich mixture number.

So oddly while the late model BMW801 used multipoint injecting, metering fuel into each cylinder via multiple cam operated plunger pumps, when in WEP it used a throttle body injection carburettor like the Packard Merlin. This was introduced on the BMW801D2 but was standard on the BMW801TS of the Fw 190A9.

When the Me 109G was introduced in May 1942 it was restricted to 1.3 ata boost for the next 18 months till about October 1943 though there was some periods of 1.42 ata boost. As a result the speed of the Me 109G1 fell from 400.5mph to 387mph for the Me 109G6 as weight and drag went up. When 1.42 ata became available speed went up to 397mph (a gain of about 10mph) so the Me 109G1 probably would have had a speed of 412mph.

The DB605 engine had three issues AFAIKT

1 when the DB605 replaced the DB601 the crankshaft bearing went from roller bearing to journal bearings that used a high pressure lubrication system, at 42psi or so much higher than the Allison and Merlin. At high altitude the oil would froth and the oil would loose a lot of its cooling and lubricating properties. This was discovered only belatedly. It was solved with a deaerating device

2 piston could burn through (a sign of preignition)

3 The original spark plug on the DB605A was the Bosch DW250ET 7 and this 
sometimes caused pre-ignition at 1.42ata MAP for the DB605A meaning 
the Me 109G frequently had to be restricted to 1.3 ata 
(atmospheres or Barr of pressure) as fuel quality was also a problem. 

New spark-plugs were needed to the end of the war for each increase in 
manifold pressure. 
1.30ata - Bosch DW250ET 7
1.42ata - Bosch DW250ET 7/1. 
1.80ata - Bosch DW250ET 7/1A and 10/1. 
1.98ata - Beru F280 E43. (Driving the DB605DCM and ASCM to 2000hp) 

My guess is that C3 fuel for the DB605A would have allowed an immediate start on 1.42ata, perhaps with time restrictions given the lubrication issue but no need to wait for better plugs or pistons.

Swedish DB605A ran at 1700hp no problems with allied 100/130. The DB605DC using C3 could run at 1.8ata (1800hp) compared to 1.42ata for the DB605A ie 22% more. DB605DC it could run at 1.45 ata with B4 only.

For some reason the DB605AM and ASM used C3+MW50 rather than just B4+MW50. It may have been required to prevent preignition, others have claim it was a precaution against fuel depletion as running out of MW50 while at 1.7 ata would cause immediate engine destruction. Obviously a pressure or flow switch is required.

C3 fuel was more expensive to produce apparently you got only 70% as much fuel for the same amount of coal and plant. However the German oil industry was introducing improvements such as alkylation to improve this and had made several others.

I estimate the allies had a 20% advantage in power due to 100/130 fuel.

Large scale production of 100/100 octane fuel was due to catalytic cracking. Houdry was the chemist, Doolittle the USAAC man that demanded it.

large scale production of 100/130 was possible due to alkylate being added.

The Germans synthesised iso-octane from syngas from gasifying coal and latter iso-butylene that they obtained in quantity from butane from their hydrogenation plants. The octane was used to improve B4 into C3. The iso-butylene was also required for the buna synthetic rubbers and this also restricted C3 production.

Thermal cracking wasn't applicable to hydrogenation based fuel but I don't know about catalystic cracking. The Germans seem to have been behind on alkylation a bit(possibly a BP patent), they started building plants in 1940 but only 1 got operation and had a few other advanced processes going as well. the Allied oil campaign had an effect on the quantity as well as quality of fuel production. Many aviation books refer to the Germans rejigging their engine production to allow multifuel engines that operate on both C3 and B4 well.

I can see only two solutions
1 early introduction of MW50 water injection, yet this only happened in April 1944 on the DB605AM and ASM. The P-47 introduced it in 1943.

2 have two fuel systems in German aircraft, one filled with C3 and the other with B4. The C3 is used when required.
some German transport aircraft used this eg the Ju 352.


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