USA produces a Mosquito-like bomber: pros and cons

[Rufus123]

The OP states a "Mosquito-like bomber", no the Mosquito itself...



...that is built either from aluminium or wood.



It is good if they can use Packard Merlin, but V-1710 will do.



They can build, say, a wooden transport aircraft.



The OP states US as a producer, and the USA was in position to build a V-12 powered bomber already in 1940, if they founded they need one.

What does Mosquito like actually mean? How similar does it have to be to be Mosquito like.

Why I thought the year was important is teh Mosquito's first light was in November 1940, introduction 1941, and didn't get into wide spread service until 1942.

We could argue that several twin engined aircraft were Mosquito like but were simply not able to do some jobs as well as a Mosquito. I would think if we wanted to match the Mosquito then we want a Mosquito. I would argue use the mosquito until something better can be found or until the need no longer exists.

By the time some saw the merits of the Mosquito a lot of other planes were already being built and were already in existence.

 

[swampyankee]

The liquid-cooled V-12s in use during WW2 were primarily developed for military use; later civil uses were largely on extemporized transport aircraft, like the Lancastrian. Conversely, while the first US radials were developed at to a USN contract, they soon completely replaced liquid-cooled engines in the commercial arena, where reliability, long life, and efficiency were of paramount importance. Considering that cooling drag is a significant factor in any piston engined aircraft, if the drag of a well-designed radial installation was as much worse as some people here seem to believe, they would not have driven liquid-cooled engines out of the commercial market. The V-12s would likely have survived if they could demonstrate significantly better sfcs, and they could not do that, either: radials, in cruise conditions had sfcs of about 0.38 to about 0.4, which is about as good as a spark ignition engine can get.

I think the primary reasons that radials get dissed so often are that the V-12 aircraft looked more streamlined and faster (probably more because "streamlined design," as in Raymond Loewy, was fashionable) than radial-engined aircraft and the P-51, which was probably the cleanest piston-engined fighter to see service had a V-12. With the exception of the P-51, which had Cd,0​ about 15% below any other piston-engined fighter to see service, the demonstrated values of zero-lift drag (Cd,0​) for all piston-engined fighters clustered between about 0.021 and about 0.025 with no significant difference between V-12 and radial engined aircraft.

 

[Jabberwocky]

What does Mosquito like actually mean? How similar does it have to be to be Mosquito like.

Why I thought the year was important is teh Mosquito's first light was in November 1940, introduction 1941, and didn't get into wide spread service until 1942.

We could argue that several twin engined aircraft were Mosquito like but were simply not able to do some jobs as well as a Mosquito. I would think if we wanted to match the Mosquito then we want a Mosquito. I would argue use the mosquito until something better can be found or until the need no longer exists.

By the time some saw the merits of the Mosquito a lot of other planes were already being built and were already in existence.

I'd take 'Mosquito-like' to mean:

Small (less than 20,000 lbs loaded);
Long-range (combat radius of greater than 600 miles);
Fast, particularly at higher altitudes (say, 360 mph plus);
Two-man;
Twin-engine;
Un-armed.

 

[Rufus123]

I'd take 'Mosquito-like' to mean:

Small (less than 20,000 lbs loaded);
Long-range (combat radius of greater than 600 miles);
Fast, particularly at higher altitudes (say, 360 mph plus);
Two-man;
Twin-engine;
Un-armed.

Lets see, the A-26 is 5mph too slow to meet the speed standard but it is close. Well, speed according to Wiki.

It has enough range.

3 man crew.

Twin engine.

It is armed.

It almost has the speed, it has the range and twin engined.

It is too heavy.

I would say it has three out of six that are met or close enough.

Looks like an heavy armed Mosquito like to me by that definition.

I think if we need a true Mosquito like the best bet is a real Mosquito.

 

[mhuxt]

The Canadian factory already has experienced people working on the Mosquito. It might be still easier to expand production there even with a labor shortage.

Like the USA Canada is not being bombed. It might even make sense to move some of the production people from Britain to Canada if there is a fear that Germany could ever attack production. Also I am sure it can be arranged if needed that US citizens could be hired to go work on Mosquito production.

I see nothing wrong with a Canadian Mosquito factory having 70% Canadians, 15% British, and 15% Americans working on planes in Canada.

I think to answer some of these questions we would need to build a production possibilities curve based on both capital (machines) and human inputs, as well as materials and try and guess at the relative merits of the items produced.

I just don't have the inputs nor the shape of the transferability curves.

Since they are already sunk costs and we would be trying to find best utility the utility will have to be calculated (well, best guess) at the margin.

Then you start getting into cost accounting issues - I'm convinced cost accountants are inherently evil, worse even than tax accountants, who are merely amoral.


Apologies to any cost/tax accountants on the board.

 

[Rufus123]

Actually one part of that is economics and another of it is finance. The finance part cannot be done properly until after the cost accountants have done their work.

 

[Rufus123]

Then you start getting into cost accounting issues - I'm convinced cost accountants are inherently evil, worse even than tax accountants, who are merely amoral.


Apologies to any cost/tax accountants on the board.

Why the dislike of cost accountants? I am not a cost accountant but I have had to work with them a number of times and have had to interpret the data from them. I did have to study it as well.

 

[OldSkeptic]

The liquid-cooled V-12s in use during WW2 were primarily developed for military use; later civil uses were largely on extemporized transport aircraft, like the Lancastrian. Conversely, while the first US radials were developed at to a USN contract, they soon completely replaced liquid-cooled engines in the commercial arena, where reliability, long life, and efficiency were of paramount importance. Considering that cooling drag is a significant factor in any piston engined aircraft, if the drag of a well-designed radial installation was as much worse as some people here seem to believe, they would not have driven liquid-cooled engines out of the commercial market. The V-12s would likely have survived if they could demonstrate significantly better sfcs, and they could not do that, either: radials, in cruise conditions had sfcs of about 0.38 to about 0.4, which is about as good as a spark ignition engine can get.

I think the primary reasons that radials get dissed so often are that the V-12 aircraft looked more streamlined and faster (probably more because "streamlined design," as in Raymond Loewy, was fashionable) than radial-engined aircraft and the P-51, which was probably the cleanest piston-engined fighter to see service had a V-12. With the exception of the P-51, which had Cd,0​ about 15% below any other piston-engined fighter to see service, the demonstrated values of zero-lift drag (Cd,0​) for all piston-engined fighters clustered between about 0.021 and about 0.025 with no significant difference between V-12 and radial engined aircraft.

We are all getting a bit mixed up here. The key is the difference needed for a military engine. Commercial ones were (and still are) optimised for basically a single altitude and power output, with little variation but for take off and climb. In this case the air cooled radials were attractive, not in the least because lot more work on them for the commercial market had been done, plus the aircraft manufacturers were used to them.
Commercial liquid cooled engines had, for commercial aircraft, seen little development.

For land transport, liquid cooled engines very quickly became dominant for similar reasons as to military aircraft engines (though if jets had not came along I think that liquid cooled aircraft engines would have dominated the commercial arena after 15 years or so, particularly when the need for greater fuel efficiency became imperative).

That is, wildly varying power loads and the need for occasional very high power settings. In this case basic thermodynamics takes over.
At high power settings air cooled engines struggle to get rid of the heat, at extreme power levels they can't (see caveat below). This is made worse with high boost levels, where a small engine is effectively acting as a much larger one, yet has a smaller mass to absorb that heat.

In an air cooled engine, ran at the highest power levels, beyond the normal cooling capacity, the only heat sink available is the engine (and oil) itself. With a liquid cooled one you have the mass of the coolant which is a better heat sink than the bare metal of the air cooled one.

If you took a small air cooled engine (say the same as a Merlin's 27 litres), boosted to the same maximum (combat rating) level ... it would melt real fast.

Secondary effects come into play, that is localised 'hot spots' around the combustion chamber. Again, with no heat sink to spread out the heat, except the metal itself (and the oil to a certain extent), it will quickly melt. The water/etc mixture quickly carries away the excess heat and even if the thermal load is ultimately higher than the cooling system will handle (say at max power) it will still cool those hot spots.

This is why air cooled engines are known as 'hard' engines, while liquid cooled ones as 'soft' ones. To prevent that (very) rapid combustion chamber meltdown typically the mixture is richened far more than is necessary for a liquid cooled one (later on water injection was used too).

Hence several things: one you can't make a similar sized air cooled engine, boost it to the same levels to get the same power as per a liquid cooled one. To get the power it has to be larger.
It's fuel consumption for the higher power settings will be greater, (a) because of the greater size and lower volumetric efficiency and (b) the need for richer mixtures.

Cooling caveat: all engines have a cooling system rated for a certain range of power levels, going above it means heat builds up.
Now you can make an air cooled engine with tremendous cooling capability (Porche as an example for the 917 and the like), but it costs a lot of money as it is much more difficult to do (plus you have size and volume issues). Plus you then have the issue then of over cooling for lower power settings.

With a liquid cooled engine it is simple to vary the cooling ability and keep the engine at an optimum temp across a far wider range of power settings, while still maintaining a better 'extreme' power setting capability and reducing hot spots.

Basically the Merlin (and the Allison) was designed from the start as a military engine, capable of widely varying power settings, including extreme levels for periods of time.
A side affect was being able to run at very lean levels (ie high combustion chamber temp levels) and enable very good cruising fuel consumption.

The big radials were basically militarised commercial engines and one result of the compromises made to achieve the performance required, was far greater fuel consumption for a given power level.

 

[Jabberwocky]

Lets see, the A-26 is 5mph too slow to meet the speed standard but it is close. Well, speed according to Wiki.

It has enough range.

3 man crew.

Twin engine.

It is armed.

It almost has the speed, it has the range and twin engined.

It is too heavy.

I would say it has three out of six that are met or close enough.

Looks like an heavy armed Mosquito like to me by that definition.

I think if we need a true Mosquito like the best bet is a real Mosquito.

Well, its 2 out of 6, maybe 2.5. That's still a fail in my book.

Given that an empty A-26 weighs more than a Mosquito - even a very late war Mosquito - does loaded, has defensive guns and was primarily a low altitude attack platform, I think we can rule it out as merely a 'heavy armed Mosquito'. That's like arguing a Hawker Typhoon is merely a heavy Spitfire...

As a bomber, the Mosquito's primary defence was speed, with a secondary defence of altitude. The earliest bomber Mosquitoes were capable of around 365-385 mph, the later bomber Mosqutioes of 410-420 mph. The A-26, although very fast at low altitudes, has nothing like the speed or altitude performance to be a US-style Mosquito. Maybe if they'd turbocharded the engines.

The Invader's 22,000 ft ceiling is only 500 ft better than the altitude the Merlin 21 powered Mosquitoes made their best speed at, and 6-8,000 ft lower than the altitude the early Mosquitoes cruised at. Late war Mossies had a best speed altitude of about 25,000 to 28,000 ft and would cruise above 30,000 ft and more than 300 mph.

To be Mosquito-like, it needs similar properties and capabilities - thus, we need a light bomber, with a moderate bomb load, no defensive armament, good spped, good high altitude performance and good range.

Turbocharge the A-26, delete the turrets, widen the bomb bay for a cookie and then you'd have a Mosquito replacement. I feel that the only problem is that this sort of aircraft wouldn't be available in major numbers until mid-late 1943.

A re-worked DB-7/A-20 with V-1650-1s might be acceptable though, and available six t eight months earlier.

 

[Rufus123]

Well, its 2 out of 6, maybe 2.5. That's still a fail in my book.

Given that an empty A-26 weighs more than a Mosquito - even a very late war Mosquito - does loaded, has defensive guns and was primarily a low altitude attack platform, I think we can rule it out as merely a 'heavy armed Mosquito'. That's like arguing a Hawker Typhoon is merely a heavy Spitfire...

As a bomber, the Mosquito's primary defence was speed, with a secondary defence of altitude. The earliest bomber Mosquitoes were capable of around 365-385 mph, the later bomber Mosqutioes of 410-420 mph. The A-26, although very fast at low altitudes, has nothing like the speed or altitude performance to be a US-style Mosquito. Maybe if they'd turbocharded the engines.

The Invader's 22,000 ft ceiling is only 500 ft better than the altitude the Merlin 21 powered Mosquitoes made their best speed at, and 6-8,000 ft lower than the altitude the early Mosquitoes cruised at. Late war Mossies had a best speed altitude of about 25,000 to 28,000 ft and would cruise above 30,000 ft and more than 300 mph.

To be Mosquito-like, it needs similar properties and capabilities - thus, we need a light bomber, with a moderate bomb load, no defensive armament, good spped, good high altitude performance and good range.

Turbocharge the A-26, delete the turrets, widen the bomb bay for a cookie and then you'd have a Mosquito replacement. I feel that the only problem is that this sort of aircraft wouldn't be available in major numbers until mid-late 1943.

A re-worked DB-7/A-20 with V-1650-1s might be acceptable though, and available six t eight months earlier.

I was just seeing how close I could come to the specifications that was posted and noted that I failed.

My thought is if the USA needs something like a Mosquito why not an actual Mosquito instead of trying to reinvent the wheel?

I understand that the Mosquito was not available in number until 1942 so I would think it would also be at least 1943 for even larger numbers of Mosquito's to be available but that is fine.

I would have no problem with the USA flying Canadian built Mosquito's if it makes sense to do so.

 

[pattle]

I don't think the A26 was really capable of doing all the jobs the Mosquito did, and I certainly can't imagine the A26 flying down Copenhagen's streets to bomb the Gestapo building or it carrying out some of the other pin point raids the Mosquito was used for. Nothing against the A26, it's record speaks volumes, it is just as awkward for me to imagine the Mosquito doing the work the A26 undertook in Korea or Vietnam .

 

[michaelmaltby]

and this:

"...The USAAF ordered 120 Mosquitos for photographic reconnaissance, but only 40 were delivered and given the US designation F-8 (6 Canadian-built B Mk VII and 34 B Mk XX). Only 16 reached Europe, where 11 were turned over to the RAF and five were sent to Italy. The RAF provided 145 PR Mk XVI aircraft to the Eighth Air Force between 22 April 1944 and the end of the war. These were used for a variety of weather, photographic, and night reconnaissance missions; as chaff dispensers; as scouts for the heavy bomber force; on "Red Stocking" OSS missions; and as H2X Mickey platforms by the 802d Reconnaissance Group (Provisional), later re-named the 25th Bomb Group (Reconnaissance). The 25th BG flew 3,246 sorties and lost 29 PR Mk XVIs on operations..."

Source:http://www.gracesguide.co.uk/De_Havilland:_DH_98_Mosquito

 

[tomo pauk]

It's not the best idea to use high altitude performance as a reference, where a large part of the drag is induced. Try using an A-5 without outer wing guns, it's got at least a similar weight and armament.

Okay. I look forward to that comparison. The 2-cannon A-3 weighted 3850 kg, vs. 4300 of the D-9.

Fact is that Focke Wulf estimated the the BMW installation on the A-9 to produce ~30% more drag than the Jumo 213A on the D-9 with radiators in minimum drag position. This mostly comes from cooling drag. However, the engine related drag is only 15% of the cd0, and therefore you're down to 4.5% engine related for the total. With radiator open, the total difference is less, and given that the other drag components should not change, engine drag is in the same ball park.

Cooling drag is firmly related to the engine type and installation, in-separable for practical examples?

The Jumo 213E installation on the Ta 152H produced more drag than the engine installation on both A-9 and D-9. So, for generalisation, what do you want to use? The in-line that is better or the in-line that is just as good or the in-line that is worse?

I look forward to the numbers that would confirm that Jumo-213E engine installation produced more drag than BMW-801D/S one. There should be no wonder that 213E was a draggier thing than 213A, however - intercooler(s) tend to increase drag.

The British built commercial airliners with in-lines, and unsuccessfully competed with US models. The Soviets built commercial air liners, and used radials. It's not even remotely true that all post war airlines operated WW2 leftover US junk and part of the reason the newly build US planes were as successful as they were is the choice of engine.

Neither the USA nor USSR were able to offer a 2000-3000 HP in-line engine, required for airlines size of Constellation- or Stratocruiser-sized airliner. The 1500 HP V-1710 won't cut it. Even the Tu-70 used 1800 HP engines, and troublesome later Klimovs won't cut it there either.
Expecting for a British airliner to compete vs. an US, post ww2 was a loosing proposal, except in UK proper and countries firmly tied to it.

Boston III compared to Mosquito, according to British sources, the A-20 was about 20% draggier than a clean Mosquito, with about 10% being attributed to engine drag, surface finish and turrets each. Mosquito lost 10% in drag from unknown sources, hence the 20% difference in the end.

If I'm reading it correctly, for the 100% of Mosquito's drag, we have 120% for the A-20? Mossie's engines were credited with 24.8 (Merlin 21) or 28.2% of the airplane's drag. Adding 10 at those values means that R-2600 installation was some 30-40% draggier. No wonder Mossie cruised as fast as A-20 was flying flat out.
We can also note that Jumo-213 was a bigger engine than Merlin, while BMW-801 was smaller than R-2600, while offering far better installation. So the difference in Allied engines (size, drag, weight, exhaust thrust, consumption) was far greater than for the German engines - and that would favor Merlin vs. R-2600 if one wants an fast bomber.

At the same time, two of the most modern British engine installations on Tempest V and Tempest II, are nearly completely equal in drag, as are engine installations on Fw 190A and Spitfire IX.

Engine installation of the Tempest V is 'most modern' only by date, it was no more modern than one at, say, Fulmar or P-40. If we want to take a look at what British really had to offer we might take a look at Whirlwind/Welkin, Mossie/Hornet, Tempest I or MB-5. Tempest V reverted from the leading-edge raditors found at Temp I because of production issues - a mere copy-paste from Typhoon guaranteed faster introduction in series production and, therefore, service use (similar as the Spit VIII vs. Spit IX). OTOH, the engine installation on Tempest II was tightly cowled and fan-cooled - a streamlined thing indeed.
We can also note that Sabre was a wide inline engine, 40 in vs 30.3 in wide Griffon, so much of the inline engine's advantage was lost.

 

[Shortround6]

The liquid-cooled V-12s in use during WW2 were primarily developed for military use; later civil uses were largely on extemporized transport aircraft, like the Lancastrian. Conversely, while the first US radials were developed at to a USN contract, they soon completely replaced liquid-cooled engines in the commercial arena, where reliability, long life, and efficiency were of paramount importance. Considering that cooling drag is a significant factor in any piston engined aircraft, if the drag of a well-designed radial installation was as much worse as some people here seem to believe, they would not have driven liquid-cooled engines out of the commercial market. The V-12s would likely have survived if they could demonstrate significantly better sfcs, and they could not do that, either: radials, in cruise conditions had sfcs of about 0.38 to about 0.4, which is about as good as a spark ignition engine can get.

I think the primary reasons that radials get dissed so often are that the V-12 aircraft looked more streamlined and faster (probably more because "streamlined design," as in Raymond Loewy, was fashionable) than radial-engined aircraft and the P-51, which was probably the cleanest piston-engined fighter to see service had a V-12. With the exception of the P-51, which had Cd,0​ about 15% below any other piston-engined fighter to see service, the demonstrated values of zero-lift drag (Cd,0​) for all piston-engined fighters clustered between about 0.021 and about 0.025 with no significant difference between V-12 and radial engined aircraft.

The advantage in streamlining got bigger and smaller over the years you describe. Also important in commercial use is the overall cost of operation and reliability. Both of which changed considerably from the 1920s to the late 40s.

The reliability of the air-cooled engines is what drove the liquid cooled engines out of the commercial market in the 20s and early 30s. Forced landings and canceled flights do NOT help starting airlines grow. The air cooled engines were often cheaper to buy and cheaper to service, the majority of high power radials in the 20s and early 30s being 9 cylinder engines as opposed to V-12 liquid cooled engines. They did not require the draining and filling of the cooling system overnight in cold climates Anti freeze not being available for aircraft use in this period (in fact engine oil was frequently drained over night in cold weather).

On such planes as the Boeing 40:

The difference in performance between an air cooled engine and a water cooled engine were minor. The lighter weight of the air-cooled engine allowed for more payload (more profit) per flight.

Air cooled engines got a boost with the Townend ring

and a much bigger boost with the NACA cowling;

Which offered around a 20mph improvement over an uncowled engine

At this point in time water cooled engines had some pretty dismal installations, fitting a streamline cowl around the engine didn't do much good if the radiators were just stuck out in the air stream with no cowling or ducts.

One reason for the push to ethylene Glycol for coolant was that smaller radiators could be used.

As the speeds that aircraft operated at increased the need to adjust the amount of cooling increased (fixed pitch props and biplanes meant 'cruising' speeds using 75-90% power) leading to adjustable cowl flaps, radiator shutters and radiators in ducts with adjustable flaps/doors.

It is a FACT that the XP-40 (after a lot of fiddling with) demonstrated 22% less drag than a P-36. Not style or fashion but speed vs power on the SAME air-frame from firewall back. It took P W until Sept 1942 to get the drag down to only 8% worse than the XP-40 on a radial engine plane. Of course by Sept of 1942 the XP-40 was no longer the height of American low drag liquid cooled installations. Later air-cooled engines did better and the even changes like going from a "B" series P&W R-2800 to a "C" series ( forged heads with much higher and closer spaced fins and more fin area on the cylinder barrels) required less airflow (drag) for the same amount of power or allowed more power for the same amount of drag. But "C" series engines don't show up until 1944, put them together with another TWO years of studying cowlings/baffles and exhaust ducting ( some of these later planes used the exhaust gases to pull cooling air through the cowling for ground running and low speeds, meaning smaller openings and NO FAN) and the cooling drag situation changed considerably from even the late 30s to 1945/46.

The Cdo doesn't measure cooling drag.

 

[Aozora]

If the USA were to build a Mosquito like bomber? Just imagine a smaller, twin engined version of this, say turbo-R-2800s:

The Republic XF-12 also shows how truly refined some radial engined installations were by the mid 1940s - 4 x R-4360s.

 

[tomo pauk]

(X)B-28 fits there, once we've ditched the turrets?

 

[davparlr]

I am not sure that the AAF saw a need for the Mosquito. By the time the Mosquito became operational in May '42, the AAF had three very capable light and medium bombers operational, the A-20, which had been operational about two years before this, the B-25, and the B-26, both of which had also engaged in combat. If it was bombing speed they needed, they already had options for this. One was the turbo-supercharged A-20 which had an estimated top speed of 388 mph at 20K, or a good 20 mph faster than the Mosquito. The turbo A-20 did have development problems but the AAF had already decided it did not need a high speed bomber. In addition, the proposal to the B-26 stated that an engine upgrade becoming available in 1942 would increase the small winged B-26 to a max speed of 368 mph at 20k ft., about the same as the Mosquito. A side note, the Martin proposal estimate of the baseline B-26A was 5 mph off. And, as for long range reconnaissance, the AAF had the F-4 (P-38 rece bird) coming out.

While the beautiful and ingenious Mosquito did some things these planes could not do I am not sure the difference would have been worth the effort.

Maintenance on wood airplanes makes be raise an eyebrow.

 

[mhuxt]

Point of Order: even the earliest Mossie bombers did 380 minimum. FB Mossies also replaced Havocs on the Intruder squadrons - the difference in effectiveness speaks for itself, have a look at 418 Squadron, the 23 Sqn ORB is also online. From memory, it took 418 a year and a half to accumulate seven kills with the Havoc, doubled that in just over a month and a half with the Mossie.

 

[Shortround6]

A big thing in convincing the PTB (Powers That BE) is that the timing is wrong for the Mosquito. The B-25 and B-26 were ordered off the drawing board (Sept of 1939) about 6 months before the Mosquito was ordered. They were designed in responce to a requirement that asked for a 3000lb bomb load to be carried 2000 miles and a top speed over 300mph. The Mosquito, in the planing stages, was supposed to carry a 1000lb bomb load. The B-25 first flies in Aug of 1940 and the B-26 and Mosquito both first fly on Nov 25 1940. At that point 1131 B-26s are on order. By the time the first Mosquito bomber gets to a service squadron over 100 each of the B-25 and B-26 have been built and at the time of the first Mosquito bombing mission (4 aircraft, May 31 1942) over 500 B-25s have been built and the number will pass 1000 in just a few more months. The B-26 is a few months behind. The A-26 project was approved back in Oct 1941 after long negotiations on price. The A-26 project slipped badly.

The B-25 had NO increase in power during it's production life. performance dropped as more guns and equipment were added.
The B-26 had a small increase in power during it's life, about 8% and saw a similar increase in weight and drag.
The Mosquito saw a considerable increase in power during it's life. Even leaving out the two stage Merlins, not all 20 series Merlins were created equal. Allowable boost went from 12lbs (or less on early ones) on the Merlin 21 to 14lbs on the Merlin 23 to 18lbs on the Merlin 25. Take-off power went from 1280 to 1610hp.

The Mosquito was a remarkable aircraft that performed a variety of jobs but it's potential in 1939/40/41 was to a large extent unforeseen. It also needed the improved fuels and improved Merlins to reach that potential. Trying to start American production in late 1942/43 would not see much in the way of service aircraft until 1944 at best.

 

[Jabberwocky]

Point of Order: even the earliest Mossie bombers did 380 minimum.

Not quite.

The earliest bomber Mosquitos, the B Mk IV with Merlin 21 engines, managed around 365-370 mph. This was due to the effect of the ducted 'saxophone' exhausts to hide the exhaust flames during night.

When these were ditched in favour of multi ejector stubs, and a few minor other aerodynamic refinements were incorporated, speed went up to about 380 mph when loaded and about 385 mph with stores out.

The very early photo-recon and night fighter variants didn't quite make 380 mph either. Early PR aircraft made 370-375 mph, and the early night fighters made about 355-370 mph.