Top 3 mistakes per country, in field of military aviation

[tomo pauk]

....
Army (and Boeing, among others) had been working on successors to the B-17 with Boeing alone going through at least eight different 'paper' aircraft. Boeing designs 316, 322, 333A, 333B, 334, 334A, 341 and finally the 345 which was the basis for the B-29 and was submitted to the Army in May of 1940. After engineering studies, wind tunnel models and full size mock ups and prototypes ordered the Army orders 250 production B-29s in May of 1941, 4 months before the first single stage Merlin production engine is delivered by Packard. Back in Sept of 1940 (end of the daylight BoB?) The Army was ordering B-17Es with eight .50 cal guns and single .30. At high altitudes they could outrun and out climb Hurricane Is . And again with a nominal range of 2000 miles with a 4000lb bomb load there was no possible single engine fighter that could escort them when they started rolling off the production lines in Sept of 1941.
Now at some point the level of technology did get to a point where a single engine fighter could perform the escort mission but that wouldn't be until 1943.
The 2 stage mechanical supercharged R-2800 wasn't really the answer. It wasn't enough lighter or more compact compared to the turbo R-2800 used in the P-47 to make up for the 350-400 less hp at 22,000ft and up.

The 2-stage mech-supercharged (did I just invented a new term...) R-2800 'B' will provide 1/3rd more power than the fully rated BMW 801D above 22000 ft (in your face, Hap Arnold), and we know that huge F4U-1 have had no problems with Fw 190 when tested. The Army fighter designed around that R-2800 does not need the 18% thick wing as the F4U, nor it does not need the 314 sq ft wing. Use 15-16% thick wing (at root), 270-280 sq ft (like Sea Fury), we'd still wind up with wing loading lower than P-47, but with more speed than the F4U. Engine available by January 1942.
The 2-stage R-2800 'A' series (= earlier model than 'B' series) was doing 1460 HP at 23000 ft, some 40% more than BMW 801C or the de-rated 801D.
The turbocharged R-2800 'A' is yet another option, feasible in 1941.

Even not going with that, the drop tanks outfitted P-47 didn't required rocket science. The US planers knew by winter of 1941/42 that targets of their bombers are within 600 miles from their future bases, and that drop tanks actually work (they know that for years, of course).

The P-51 with V-1650-1 would still give the Fw 190 good run for their money, especially in 1942.

 

[stona]

In the context of my earlier post it is only fair to note that when the USAAF did finally get the escort fighters, tactics and strategy for its bombing offensives sorted out it scored the one clear victory of the combined bombing offensive and that was the destruction of the Luftwaffe (or German Air Force as it liked to call it) in 1943/44. This was an almost entirely American victory, expensive in blood and treasure, and an important one for which enough credit is not always given. Had the Americans turned to night time bombing who knows what might have happened (apart from a lot more night fighters!).
Cheers
Steve

 

[tomo pauk]

Three top mistakes for the UK might possibly been:
- Too much of adherence to the 'bomber will always get through (during the day)' mantra. From there several things (problems) emerged: neglection/rejection of long range fighter escort design/service, the turret fighter (to combat enemy bombers trying to get through), non availability of technology and training for night bombing
- Belated introduction of high performance aircraft in the FAA inventory
- Belated introduction, or non-introduction of advanced airfoils and high lift devices as a norm, rather than as an exception

 

[stona]

Everyone thought that the bomber would get through in the 1930s, only the Americans continued to believe so in the 1940s.

You don't need long range fighters or bombers when you are expecting to have a conflict with France. The fighters were designed around the requirements of ADGB, only the zone fighters needed any kind of endurance and as the zone and interceptor fighter specifications became more blurred and converged endurance/range was sacrificed for performance. At the time this was a reasonable route to take.

Turret fighters seemed like a good idea at the time. With hindsight something closer to the German 'zerstorer' concept would have been better, but even that had limitations. Designs much closer to a heavy fighter/zerstorer were considered in the early to mid 1930s, but the turret concept won out. I still believe this was due at least in part to financial considerations. A suitable French turret was available, the rights already in British hands, and there would be no substantial development costs.

The non-availability of training and equipment for night bombing was undoubtedly a mistake, but it was founded on an underestimation of just how difficult it was to navigate in the dark. I'm not convinced that with the technology available in 1940/41, even with much increased and better training, significantly better results would have been achieved. The technologies that enabled effective, if not precision, night bombing did not become available until much later.
GEE from March 1942. OBOE from December 1942. G.H. and H2S November 1943. LORAN, very late 1944, hardly used at all.
Unfortunately there was no way that any of this technology can be magically advanced by a couple of years making it available in 1940 as Bomber Command switched almost exclusively to a night time effort.

The lack of high performance aircraft in the FAA was a mistake, or rather a combination of mistakes. Fundamentally the Senior Service was run by sailors, not airmen, and it was slow to grasp the rapid changes taking place in the late inter-war period. Their Lordships very nearly went to war without a fighter capable of protecting its fleets and they did go to war with strike aircraft that looked like they belonged to a previous era. We should be grateful for the Fulmar which was not as bad as it is often portrayed to be.

I'm not sure what you mean about airfoils and wing design, you' need to be more specific. The performance of the best British aircraft in all categories, apart from naval, in the latter part of the war was as good as or better than any other nations (say Spitfire, Tempest, Mosquito, Lancaster).

Cheers

Steve

 

[tomo pauk]

With France assumed as ally in upcoming war against Germany, the escort of RAF bombers makes plenty of sense. Base the fighters in France (not unlike what was done in ww1), bombers taking off from UK, then overfly the Channel and France, where they are joined with fighters, then carry on into Germany proper. Damaged bombers can land in France, or maybe in Belgium/Netherlands that we assume as neutral. Fighters can have 250-300 miles of radius, and Merlin I/II/III has something like twice the power above 16000 ft than the main German fighter engine of late 1930s, the Jumo 210. Merlin III/X, let alone Merlin XX are also better than DB-601A, especially with 100 oct fuel. Or Sabre vs. BMW 801.

The Germans were not really sure that bomber will always get through, the Bf 110 (while non-ideal) was very much a fighter that was to clear the way for the upcoming bomber strike. They almost got the Fw 187 for similar purpose. The Japanese were also not sold to the idea.
A long range fighter was very much within the scope of UK technology from mid-30s on, more so than it was the case for any other country, but a firm separation between FC and BC, reinforced by 'will get through' mantra, meant it will never, or too late came to frutition.

I did not state that advanced airfoils and high-lift devices were not present on all British aircraft, but that outdated airfoils and non-applications of hi-lift devices were present in plenty of their A/C.

 

[stona]

Germany only emerged as a potential adversary in the two years after the NSDAP's consolidation of power and self evidently after the Anschluss and Munich in 1938. Even with remarkable powers of perception this could not be before late 1934 or early 1935 when the Nazis truly took control and realistically voices didn't start to be raised in concern until about a year after that.
Given that at this time it was expected to take 8 years to introduce a new bomber into service from first design and 4-5 years for a fighter I think the familiar crystal ball would be needed.
Rearmament in Britain gained pace with Scheme F introduced in 1936, by which time Germany was emerging as the potential enemy, but even then deliveries of the orders for the scheme were scheduled for between February 1939 (Battle) and August 1939 (Hurricane, Wellington) and even this was not achieved. Of the 270 Spitfires supposed to be delivered by just 130 were completed by April.
In the period between 1935 and 1938 the total number of aircraft delivered rose from 893 to 2,828 but rocketed to 7,940 in 1939. The total structure weight went from 1.91 to 9.82 million pounds in the same period before rocketing to 28.89 million pounds in 1939. Equivalent figures for the total work force are 15,000 (1935) 65,000(1938) and 130,000 (1939).
The process was much longer and slower than seems to be the perception here. Britain entered the war with aircraft designed in the mid 1930s (or earlier) not in 1938.
The increased production of 1939-1940 was based on investment in fixed capital (the firms felt secure in doing so), better state-industry planning (a looming war concentrates minds), the stabilisation of design (not new designs), improved design and construction methods (though you might not think so building Wellingtons at Weybridge) and finally the extended use of sub contracting.
Cheers
Steve

 

[Shortround6]

The point was that while the inability of the bombers to defend themselves in daylight was shown to be true in 1942/early 43 that is more than a little late to start designing escort fighters. Before then things were more confused and I hope that I showed that in late 30s a single engine fighter could not hope to match the range/endurance of a 4 engine bomber. 3 (at a minimum) things changed this.

1. Better aerodynamics. Like the airfoil used on the Mustang that allowed for the carriage of large quantities of fuel while keeping the drag low.
2. Better fuel. While the Americans had moved from 87 octane to 91 octane and then 100 octane while the British were stuck on 87 octane the American 100 octane had lower peak performance capability than the British 100 octane. It wasn't until 1941/42 that 100/130 was finally sorted out and engine makers (and aircraft designers) could get a good idea of what they could expect.
3. Better engines and superchargers that combined with the better fuel allowed for much better power to weight ratios than early powerplants could offer.

When the planners could count on such changes is a real question. We know now when such changes occurred but trying to predict these changes would occur in 1939-40-41 was a lot harder.

I am really not sure where this "Mystery" R-2800 powered fighter comes from or how it fits in. Who builds it and when is it ordered?
The First R-2800 doesn't get into the air until July 1939 in a test hack. The F4U was the first airframe designed to use the R-2800.
The single stage engine in the P-47 is about 200lbs lighter than the two stage engine in the F4U and both planes need inter-coolers

 

[stona]

The inability of the US bombers to defend themselves was proven in 1942. The inability of German and British bombers to defend themselves had been demonstrated in 1939/40. The American faith in the ability of their bombers to defend themselves by dint of much heavier armament was the mistake. I don't know enough about the policy making process behind the USAAF's adoption of the principle that given enough guns a formation of bombers would be able to defend itself, but there must surely have been some doubters given events in Europe two years earlier. Were there no Cassandras being ignored in 1940/41?
Cheers
Steve

 

[Shortround6]

A long range fighter was very much within the scope of UK technology from mid-30s on, more so than it was the case for any other country, but a firm separation between FC and BC, reinforced by 'will get through' mantra, meant it will never, or too late came to frutition.

Sorry Tomo but it wasn't possible in 1930s. It was possible in 1942. The question was when it became possible.

As mentioned above it was fuel and engines, The Merlin III gave 880hp for take-off with 87 octane fuel. Even if the British had gone to constant speed props sooner that is not enough power to get a fighter with the capability of a 400 mile escort mission (roughly 1200 miles 'nominal range') out of a standard British Airfield. Yes, "technically" the British could have made the airfields bigger pre-war but financially it was another story. Initial specification for the Stirling bomber called for operating out of a 500yd field.

A Merlin III went 1375lbs, A Merlin XII went 1420lbs, The Merlin X and XX went 1450lbs for 1280hp take-off. Late model 20 series engines went 1475lbs and were allowed 1610hp for take-off using 18lbs of boost. Merlin 61 weighed 1640lbs and was rated at 1280hp for take-off. Merlin V-1650-7 weighed 1715lbs and had 1490hp for take-off using 15 1/4lbs boost on 100/130 fuel. The power to weight ratios of the powerplants (and the fighters) changed dramatically in just 4-5 years. Where was the 'tipping" point at which a long range fighter (which is a very imprecise phrase, a P-40C was long range fighter compared to a Spitfire MK I) became feasible?

And the question isn't just about take-off, it is about providing a fighter that is good enough to actually fight the enemy interceptors over their home territory. Which the Bf 110 wasn't able to do. You may not need to shoot down the enemy at a 5 to 1 ratio but you need to disrupt his attacks on the bombers and keep his interceptors busy. If your escort fighter is bigger and heavier and using roughly the same engine you are in trouble.

Now you just need a design team that is clued into engine (and fuel) development enough to rapidly respond with a good design and get it into production in months rather than the normal 2-3 years (or 4 years). You also have to compromise on certain things. The US army in 1942 wanted high speed, high altitude and long range. What they got was the Fisher P-75.

 

[stona]

The British were not looking at for a long rage fighter for the RAF. The nearest thing to it in 1940/41 would be something like the Fulmar and that couldn't compete with the Bf 109 anywhere. The Spitfire and Hurricane were both produced as a result of a conscious decision to sacrifice endurance for performance. It was not accidental that the RAF's two best fighters in this period had such limited range, it was intentional. The factor which most influenced the decisions influencing this generation of British fighters was not the performance of other nations fighters, though they were not ignorant of it, it was the rapidly increasing performance of bombers.

Between 1930 and 1936 the British went from the Bulldog, incapable of reaching 200 mph, to the Spitfire. The specification for a Bulldog replacement, F.7/30, was issued in October 1931 (NOT 1930) and called for a top speed of 195 mph and at no time in its evolution was a speed of more than 215 mph mentioned. A few years later and F.10/35 would be met by the development of designs funded as part of the Air Ministry's high speed aircraft research programme, aircraft flying in the 300-350+ mph range. It was a considerable achievement, but that performance came, knowingly, with the sacrifice of endurance.
All aircraft designs are a compromise and at the time these aircraft were being developed, the Spitfire and Hurricane being produced in numbers, the primary driving factor was the quest for speed.

Cheers

Steve

 

[Shortround6]

I don't know if it was "intentional" but the Spitfire and Hurricane were no more short legged than another European fighter of the time. Or perhaps I should say any other European fighter that the British had reasonable knowledge of. Russia may or may not qualify as European and in 1937-39 only the I-16 was really "known" in the West. Japanese fighters also being unknown or known from Chinese reports and with the Ki 27 first flying 7 months after the Spitfire even if the British had been handed a full set of blueprints it wouldn't have changed a thing. The Ki 43 first flying almost 3 years after the Spitfire.
Deliberately designing (requesting) a slower, poorer climbing, larger turning radius aircraft that had more range than it's contemporaries in the mid to late 30s would not have gone over well. It didn't go over well when the British got their hands on the early P-40s. They promptly shuffled them off to fight the Italians. Early P-40s having 35-60% more internal fuel than a Spitfire (depending on self sealing tank set up) and provision for the 52 gal drop tank? With drop tank the P-40 had nearly double the fuel of an early clean Spitfire.
The early Allison was good for 1040hp at 15,000ft which wasn't that far off form the Merlin IIIs 1030hp at 16,750ft.
In other words sticking a Melrin III in Tomahawk would have done almost nothing for altitude performance.

 

[michaelmaltby]

"...The American faith in the ability of their bombers to defend themselves by dint of much heavier armament was the mistake....."


The 'Custer' Mistake

 

[stona]

I don't know if it was "intentional" but the Spitfire and Hurricane were no more short legged than another European fighter of the time.

The only European fighter of comparable performance to the Spitfire, in service in meaningful numbers, by 1939, was the Bf 109. It's a case of convergent evolution. I believe some of the better French fighters like the M.S. 406 had better range, but in no way qualify as 'long range'.
The sacrifice of range was intentional in the sense that the high speed aircraft research programme explicitly accepted that the compromise, reducing endurance for performance, specifically speed, would have to be made.
Cheers
Steve

 

[tomo pauk]

Sorry Tomo but it wasn't possible in 1930s. It was possible in 1942. The question was when it became possible.

As mentioned above it was fuel and engines, The Merlin III gave 880hp for take-off with 87 octane fuel. Even if the British had gone to constant speed props sooner that is not enough power to get a fighter with the capability of a 400 mile escort mission (roughly 1200 miles 'nominal range') out of a standard British Airfield. Yes, "technically" the British could have made the airfields bigger pre-war but financially it was another story. Initial specification for the Stirling bomber called for operating out of a 500yd field.

How bad the RAF wants the long range fighter (yes, we know they don't want it)? Lengthening 1/5th of take off lanes by extra 200 ft (70 yards?) to accomodate the longer ranged fighter should be cheaper than to produce bombers that Germans will make the practice shooting of.

A Merlin III went 1375lbs, A Merlin XII went 1420lbs, The Merlin X and XX went 1450lbs for 1280hp take-off. Late model 20 series engines went 1475lbs and were allowed 1610hp for take-off using 18lbs of boost. Merlin 61 weighed 1640lbs and was rated at 1280hp for take-off. Merlin V-1650-7 weighed 1715lbs and had 1490hp for take-off using 15 1/4lbs boost on 100/130 fuel. The power to weight ratios of the powerplants (and the fighters) changed dramatically in just 4-5 years. Where was the 'tipping" point at which a long range fighter (which is a very imprecise phrase, a P-40C was long range fighter compared to a Spitfire MK I) became feasible?

The tipping point is achieved once Merlin I/II/III is available. It provieds twice the power of what Jumo 210 was doing. Another tipping point is achieved with Merlin XX, that does not have peer in LW service before late 1941, when DB 601E is finally cleared for 2700 rpm.

And the question isn't just about take-off, it is about providing a fighter that is good enough to actually fight the enemy interceptors over their home territory. Which the Bf 110 wasn't able to do. You may not need to shoot down the enemy at a 5 to 1 ratio but you need to disrupt his attacks on the bombers and keep his interceptors busy. If your escort fighter is bigger and heavier and using roughly the same engine you are in trouble.

Didn't I've alredy stated that Bf 110 was not ideal for the job? Keep things simple - 1 or 2 (in German case) crew members, 8-12 LMGs, either Merlin or DB 601, not too big and that's it. RAF has advantage in engine power at altitude at least by late 1941.

Now you just need a design team that is clued into engine (and fuel) development enough to rapidly respond with a good design and get it into production in months rather than the normal 2-3 years (or 4 years). You also have to compromise on certain things. The US army in 1942 wanted high speed, high altitude and long range. What they got was the Fisher P-75.

Not every long range fighter was a lemon like P-75. Talk P-47N, Merlin Mustang, P-38, P-82, Hornet.
As for earlier stuff - Westland can very much design the Whirlwind-like fighter instead of historical Whirly, but a bit bigger, say 300 sq ft wing, Merlin engines in power egg installation, fuel both outboard and inboard the nacelles, 12 Brownings.

...
Deliberately designing (requesting) a slower, poorer climbing, larger turning radius aircraft that had more range than it's contemporaries in the mid to late 30s would not have gone over well. It didn't go over well when the British got their hands on the early P-40s. They promptly shuffled them off to fight the Italians. Early P-40s having 35-60% more internal fuel than a Spitfire (depending on self sealing tank set up) and provision for the 52 gal drop tank? With drop tank the P-40 had nearly double the fuel of an early clean Spitfire.
The early Allison was good for 1040hp at 15,000ft which wasn't that far off form the Merlin IIIs 1030hp at 16,750ft.
In other words sticking a Melrin III in Tomahawk would have done almost nothing for altitude performance.

By the time P-40C is available, the Merlin 45 is around (the Merlin XX even earlier), so let's stick that one. No wonder P-40C was a worse performer than Spitfire V, at 15000 ft it has 300 HP less and admitedly greater weight.
edit: the Spitfire with 20-30 gals extra is a better bet
(end edit)
I don't know why the long range fighter with 8 Brownings in case of UK will be slower, a worse climber and more sluggish than an interceptor with 4 Hispanos.
P-40 was not the only long range aircraft with humble power, let's take a look on the Ki 61, granted a mid-war aircraft, but using an engine of less power than Merlin III or the early V-1710.

The fact that escorting fighters are already at 15-20 kft, cruising at 250 mph puts them in advantage vs. defendes that need to climb 1st to get there - altitude and speed advantage counts for something. The defending side can call up the fighters that are nearby, say those at Ruhr area, while those around Hamburg, Munich or Berlin can't help. Makes things interesting - 500 bombers and 200 escorts vs. 250 defenders?

 

[stona]

The endurance of the Spitfire and Hurricane have their origins in the 'Operatonal Requirements Committee' and it's requirement for F.10/35, though neither was built to that specification.
At discussions on 29th March 1935 speed and firepower were given priority over rate of climb and manoeuvrability and landing speed requirements were omitted, possibly because more and more aircraft were now being designed with flaps. An armament of 6, preferably 8, .303 machine guns was required.
For the first time a table was introduced which showed the estimated relationship between endurance and maximum speed. The DCAS (Courtney) proposed that endurance should first be decided as this would determine maximum speed. Wing Commander H A Whistler gave the views of ADGB. He asked for fuel for 30 minutes at ground level (or at 15,000ft, whichever gave the greater) at maximum continuous power to cover climb and fuel reserve, plus 60 minutes at economic speed at 15,000ft for patrol, plus 15 minutes at maximum power for pursuit and attack. This was agreed.
The concept of determining fuel capacity by reference to a hypothetical operational mission was entirely new, and much better than the previous practice of just specifying a time at maximum power. Whistler's detailed prescription was equivalent to 60 minutes at maximum power plus a 15 minute reserve. This equated to a maximum speed of 315 mph in the table.
By the time the specification was circulated Courtney noted that the new aerodromes being built allowed a run of 1,100 yards and that this would permit an increase in wing loading to allow a maximum speed of 330 mph.
Both the Spitfire, being built to the F.37/34 version of F.7/30, and the Hurricane, being built to F.36/34, incorporated the requirements of F.10/35 into those aircraft and that's why the endurance and maximum speed of both is roughly in this range. They are based on a requirement dating from March 1935 when a high speed (300+mph) long endurance fighter was not deemed to be possible.
Cheers
Steve

 

[Peter Gunn]

Sadly, I am in no way smart enough to add to this discussion, but I am certainly learning a ton of good stuff. Thanks guys, please continue and well done.

 

[soulezoo]

I agree with you Peter. Much to be learned.

Best of all, the lads are keeping it civilized!

 

[pinsog]

Many of you guys keep talking about the "myth of the self protecting bomber". I'm not really sure why this is considered a "myth". In 1940 there at most, 2 countries in the world that would be capable of intercepting B17's with any real hope of success, the Germans and maybe the British. As was pointed out above, the B17E could actually outrun and outclimb a Hurricane, and a 1940 model Spitfire with 8 303 LMG's would't really excite me when trying to attack a plane that has 8 50's to shoot back at me with, plus the fact that the Spitfire wouldn't have a huge speed advantage itself when you begin talking about multiple passes at altitude that a Spitfire would need. The Spitfires couldn't even deal with Japanese twin engine bombers in 1942-43 over Port Moresby when they had a pair of 20mm cannon, so why would we think they could handle a B17?

The Japanese were never very good at shooting down 4 engine heavy bombers and when the B29 arrived it was virtually immune. The Zero would have nearly the same problem as the Hurricane in catching a B17 at altitude.
The Italians wouldn't be a threat.
The US themselves only had 2 planes that could catch a B17 at altitude at that time, the P38 and the P43, neither of which was really combat capable and the P43 being very underarmed.

The Germans best hope at that time would have been the BF110 which would probably have done a very credible job, the ME109 probably doing ok, but still being underarmed and not carrying enough cannon ammunition.

All that being said, the Germans made quite an advancement in their ability to shoot down heavy bombers, but they were using 1940's tech to shoot down 1930's bombers. They never faced the B29. A B29 at 33,000 feet at 300-325-350 mph is a far different animal than a B17 or B24 at 24,000 feet at 200 mph

 

[Shortround6]

How bad the RAF wants the long range fighter (yes, we know they don't want it)? Lengthening 1/5th of take off lanes by extra 200 ft (70 yards?) to accomodate the longer ranged fighter should be cheaper than to produce bombers that Germans will make the practice shooting of.

What take-off lanes? RAF 'Fields' were pretty much exactly that, 'fields'. Grass "fields" roughly square in shape so the planes could take off in whatever direction the wind was coming from. The Grass Field presented another problem. To prevent heavy aircraft from putting ruts in the field ALL aircraft, bombers and fighters, had were limited to the same maximum tire pressure. It was only as the war got closer that fields were extended by buying or commandeering neighboring property and a few planes were granted exemptions form the tire pressure limit. Whirlwind was allowed 42psi instead of the standard 38psi for instance to avoid redesigning the engine nacelle and doors.

The tipping point is achieved once Merlin I/II/III is available. It provieds twice the power of what Jumo 210 was doing. Another tipping point is achieved with Merlin XX, that does not have peer in LW service before late 1941, when DB 601E is finally cleared for 2700 rpm.

The Merlin I/II/III was hardly a tipping point as the British were well aware that the Jumo 210 was Kestrel class engine and that the Germans would be working on something better in short order (if not already, Germans didn't put out press releases unless it put them in a favorable light). The French already had 860hp Hispano engines and were working on improving them. Germans were displaying 950hp DB engines in international flying meets in mid 1937.
Designing a long range fighter when the Germans are flying Jumo powered 109s is one thing, actually flying them in service once the DB powered 109s reach the squadrons is another story.
Germans do not have to match the Merlin for power. The interceptor fighter does have to come close in power to weight ratio though, which means the defending fighter can equal the performance of the escort fighter while using a lower powered engine if the defender is light enough.
Germans were using the DB 601N engine with 1175PS at about 16,000ft in the Fall of 1940 (some had shown up in the summer of 1940). Only a few hundred to be sure but then the British didn't instantly replace all Merlin IIIs with Merlin XIIs and Merlin 45s in a matter of a few weeks either.

Didn't I've alredy stated that Bf 110 was not ideal for the job? Keep things simple - 1 or 2 (in German case) crew members, 8-12 LMGs, either Merlin or DB 601, not too big and that's it. RAF has advantage in engine power at altitude at least by late 1941.

Mentioning the Bf 110 was to show that it is not enough just to have some sort of fighter show up. The fighter has to able to put up a creditable fight which the 110 could not. BTW the armament in the 110 was no heavier than what you are proposing. 4 LMG and 2 light cannon aren't much different in weight than 8 LMGs and and lighter than 12 LMGs. It rather depends on ammo carried.

Not every long range fighter was a lemon like P-75. Talk P-47N, Merlin Mustang, P-38, P-82, Hornet.

True but then the P-47N, the Merlin Mustang and the P-38 were not designed to be escort fighters. They were adapted from existing designs which means they managed to avoid some of the unrealistic "wish list" type requirement/s that bedeviled many new aircraft.
They also benefited immensely from the better fuel and engines. A P-47N with R-2800-21 engine without water injection and a tooth pick prop trying to fight with 500 gals of internal fuel??? even if you left 1/2 the guns home and 3/4 of the ammo things might not look good. Same with The Mustang. The two stage Merlin gave several hundred more HP for only a few hundred pounds of powerplant weight. P-38E with the 1150hp engines and 400 gallons of fuel after the drop tanks are gone? Got to loose 600lbs of something, guns/ammo/etc to get the performance back. 600lbs might be worth 200fpm of climb to the P-38 (or more?)

By the time P-40C is available, the Merlin 45 is around (the Merlin XX even earlier), so let's stick that one. No wonder P-40C was a worse performer than Spitfire V, at 15000 ft it has 300 HP less and admitedly greater weight.
edit: the Spitfire with 20-30 gals extra is a better bet

OK My mistake, the P-40C did show up late, but Tomahawks with 160-180 US gallons of internal fuel (ex-French contract) were showing up in England in the fall of 1940. The extra fuel was certainly not the only reason for the extra weight but these P-40s were real airplanes and not a hypothetical aircraft of rather indeterminate performance. Some of these Tomahawks were "rated" as having a range of 1200-1300 miles which only seems possible if the pane was towed into the air, the engine started and then flown at the exactly right altitude/speed until the fuel ran out. In other words the rating is bogus but obviously they had more range than a Spitfire. Again, like the Bf 110, range wasn't the only requirement. The fighter had to be able to actually have a decent chance of fighting in the environment of the time.

P-40 was not the only long range aircraft with humble power, let's take a look on the Ki 61, granted a mid-war aircraft, but using an engine of less power than Merlin III or the early V-1710.

Uh, no. It had more take-off power than either and had very close to the same power at altitude. With 121 imp gallon of internal fuel (145US?) it's range had a lot more to do with better aerodynamics (less drag) than fuel capacity. Claiming you could design a fighter in the mid 30s that could match a fighter that started design in 1939 ignores the lessons learned in the intervening 3-4 years.

The fact that escorting fighters are already at 15-20 kft, cruising at 250 mph puts them in advantage vs. defendes that need to climb 1st to get there - altitude and speed advantage counts for something. The defending side can call up the fighters that are nearby, say those at Ruhr area, while those around Hamburg, Munich or Berlin can't help. Makes things interesting - 500 bombers and 200 escorts vs. 250 defenders?

The beginning part of your scenario only works if the defender has a really crappy early warning system (near border/coast or telephone system doesn't work? ) radar was not a necessity. Even the Chinese managed 20-30 minute warnings for raids from Japanese bombers at times. A fair number of the defenders would already be at altitude waiting for the raiders to show up although even with early radar exact location and especially altitude were often in error.

 

[Shortround6]

Many of you guys keep talking about the "myth of the self protecting bomber". I'm not really sure why this is considered a "myth". In 1940 there at most, 2 countries in the world that would be capable of intercepting B17's with any real hope of success, the Germans and maybe the British. As was pointed out above, the B17E could actually outrun and outclimb a Hurricane, and a 1940 model Spitfire with 8 303 LMG's would't really excite me when trying to attack a plane that has 8 50's to shoot back at me with,................

Several other things affected the US planning/theory of bombing. One was that the support equipment for the crew was not up to the altitude capability of the aircraft itself. The heated flying suits for gunners (or heating in general) was not up to the demands placed on it. In the 30s in was assumed that just providing oxygen to the crew would be good enough for 6-8hour flights at 30,000ft. It wasn't, Oxygen masks allow shorter flights at 30,000ft but not flights of the duration the bomber missions wound up lasting.
Pre war planning didn't really include formations of hundreds of bombers. Large formations having to fly lower and slower than small formations.
The added equipment (including guns/ammo) didn't help altitude performance either. Weather (clouds) over Europe also caught the USAAF a bit by surprise ( a little less sympathy here).
It all added up to actual operations being flown 5-10,000ft lower than pre-war planning/theory called for.

US had also fallen into the same trap as many other air forces in believing small quantities of small (250-500lb) bombs could be delivered with precision/accuracy and get decisive results.