Optimize the FW190 for the Eastern Front

[Shortround6]

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.

 

[tomo pauk]

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.

 

[Shortround6]

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?

 

[kool kitty89]

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)

 

[Shortround6]

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.

 

[tomo pauk]

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.

 

[dedalos]

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

 

[kool kitty89]

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)

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.

 

[tomo pauk]

...
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

 

[Denniss]

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).

 

[tomo pauk]

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.

 

[Shortround6]

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.

 

[kool kitty89]

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.

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)

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.

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.

 

[tomo pauk]

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

 

[dedalos]

.


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

 

[wiking85]

.


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

I thought the Homare used 90 octane fuel?

 

[tomo pauk]

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.

 

[kool kitty89]

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)

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)

 

[Koopernic]

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.

 

[tomo pauk]

Some comments

...
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.