Build an improved Gloster F5/34

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Challenge is the F5/34 was never intended to run the Mercury, but instead the more powerful, but then unavailable Perseus. How does the Junior compare in hp, etc
I'm not concerned with dead end design specs that had to changed and were never used.
The engine the plane actually used was the Mercury, so that's what I'm using as a comparative.
 
OK, lets compare the two engines

Engine........................................Mercury VIII......................Perseus X
take-off power...........................725hp....................................750hp
Power at alt..............................840/14,000............................880/15,500
Weight............................................1010lbs.................................1110lbs

Anybody see a big increase in performance here? A whopping 5% power at altitude?

There were higher powered Perseus engines but just about all of them used a modified supercharger for lower altitude work.
Getting 905-930hp(?) at 6,000-6500ft and another 80-140hp for take-off, while good for torpedo bombers, gives you a real clipped wing chicken (crippled flight) for a fighter instead of a Hawk.

And even in fantasy land if we build Perseus engines that give the exact same power as Hercules engines per cylinder we get just over 800hp at 16,000ft using Hercules III cylinders and supercharger and not much more using Hercules VI cylinders and supercharging until you use 100/130 fuel.
Please note that the Perseus as built ran slightly slower than the Hercules and was never allowed to use more than 3.5lbs boost except for the Perseus XA on take-off.

Now using the specs from the Hercules VI and 100/130 fuel we can get a 9 cylinder engine up to 993hp at 15,500ft. But that is well into 1941.
 
The article has its good and bad guys with too many adjectives for my tastes. Predicting the future is a great way to look foolish but predicting the past is easy.

Singapore Island had a pre war population of around 558,000 people (350,000 in the city) on 225 square miles, Malta had around 241,000 people on 122 square miles. Given the population and that most of the Singapore water supply came from Malaya calling the island a fortress was ignoring reality. At the same time the only viable threat came from the Japanese, who would need to capture bases in places like the Philippines, French Indo China, the Dutch colonies and/or Thailand before they could do more than raid, there would be lots of warning. The IJN had no developed plans to strike European colonies pre 1940, only against the US ones. In naval strength terms the 9 Japanese to 15 American battleships were considered to be an 81 to 225 combat power, against the 21 Anglo French 81 to 441. It was hard to see how a Japanese strike south would not be opposed by at least the Anglo French. Anyway it was widely known as absolute no need to check fact Asian militaries were inferior in all respects, look how bogged down Japan become in China.

The June 1940 events radically changed things, a rough equivalent of expecting Australia to currently have defence plans based on the assumption Indonesia signs an alliance with China allowing extensive basing rights and use for any purpose.

I do not have a peacetime personnel strength for the IJN, in December 1941 it was around 300,000 and for Australia to rely on its own Navy (or even Air Force) would require a credible percentage of the IJN, plus civil personnel in at least the repair facilities even if most ships and aircraft were built overseas. The Australian population in 1939 was 6,960,798 in 1945 was 7,376,567, or about a tenth that of the Japanese home islands.

Australian military personnel (Male / Female / grand total)
9/39, 14,903 / 0 / 14,903
11/41, 364,874 / 3,785 / 368,959
8/42, 634,645 / 21,451 / 656,096
8/43, 685,946 / 46,054 / 732,000
8/44, 649,363 / 47,703 / 697,066
6/45, 599,277 / 44,728 / 644,005
6/46, 132,062 / 11,401 / 143,463
6/47, 54,463 / 949 / 55,412

The Navy peak wartime strength was around 40,000 after starting at around 8,000. According to John Ellis some 1,340,000 served in the military at one time or another.

Apart from the World War I debts Australia had many overseas loans to pay for development, payments for which created considerable pain during the depression.

Australian defence planning in the 1930's was effectively based on the assumptions any threat would come from Europe, the Australian Military would therefore mostly move there and would be part of the Empire military, this required a common doctrine and equipment, US Aircraft were built using all sort of different standards to British ones. Any aircraft sent to Australia were effectively lost to the European strength. Buying from the US was expensive, military orders would be terminated as soon as war broke out and worse probably spare parts supplies as well. Even if that changed the ability to generate US dollar income would be reduced as the local economy switched to a war footing. It is interesting the Australians ordered Twin Wasp engines for their Hudsons which at least gave the chance of local spare parts production, the RAF had no local source of engine spares for their Hudsons. How goes Coastal Command in 1939/41 if the Hudsons are deprived of spare parts? The British had much more leverage with the US than the Australians. Canada had a "special relationship" and was free of the risk of bomb raids. The US were world leading in many aspects of civil aviation but in the second half of the 1930's were falling behind Europe in military types and production capacity as the Europeans dramatically increased their military spending. The decision to make Wirraway provoked a big local backlash "British is Best" was a widely held belief, plenty of "never vote for you again" letters arrived. The opposition died down with the RAF Harvard order and the way the RAAF added its Hudson order to the RAF one. The next hurdle was how many Wirraway did the RAAF need, there was no export market and the 1939 peace time limits on the planned RAAF size. War seemed to be coming, but when?

A European enemy was expected to send maritime raiders into the southern hemisphere, more than just float planes would require the IJN to include one of its 6 carriers in the force and given IJN base locations it would be a raid, carriers operated alone, could be overwhelmed by a relatively small strike force and had inferior aircraft than land based ones, everyone agreed carriers versus land based air power was bad for the carriers. Given the weight of attack shipping would be the main target, a few bombs on land targets were probably not worth the risk.

The RAAF would be expected to provide tactical reconnaissance for the Army, maritime search and strike, even if it had fighters, given their range and the size of the continent they needed plenty of warning to move to the threatened location or lots of bases with around a carrier's worth of fighters in each.

RAAF pre war orders, number, details
18 Hawker Demon order, approved 15 November 1933.
24 Seagull V order (approved 26 January 1934) London order 416 (ordered as 6+6+12) Air 2/1791 says final 12 ordered 1 May 1936 under contract 323214/34. 12 received in 1935, next 12 received starting December 1936.
1 DH.89 Rapide London Order approved 15 January 1935. There should be a second order for 1 or was it civilian leased/bought?
24 Hawker Demon order approved 29 January 1935 (London order 452)
12 Avro Cadet order approved 1 May 1935, London order.
(12) Avro Cadet order plus 3 spare engines, as coverage for delays in Demon deliveries, cancelled, order number reused. A draft Agenda, deferred, request to return documentation made 14 August 1935.
6 DH.60 Gipsy Moth officially built by De Havilland in Australia from a mixture of imported and local parts. Delivered October 1935 to June 1936.
12 Hawker Demon order approved 11 November 1935. London order 452A
33 Avro Anson order approved 11 November 1935, London order 479, which was also a provisional order for Avro Cadets not proceeded with.
5 Avro Anson order approved 11 November 1935, London order 496, dual control for training
10 Hawker Demon order approved 18 August 1936, London order. Air 2/1791 says Air Board Order 524 sent by airmail 15 Oct 1936. Plus 24 conversion sets to dual trainer version under order 532.
10 Avro Cadet order approved 29 August 1936? London Order 525. Air 2/1791 says Air Board Order sent by airmail 15 Oct 1936.
40 Bristol type 149 (Bolingbroke) advanced notification sent 24 November 1936, approved 2 March 1937. London order 550
6 Westland Wapiti order, second hand from RAF, requested 7 July 1937, to supplement the earlier Wapiti orders.
1 Miles Magister order Overseas Indent 584 approved 8 October 1937.
1 Wirraway order, (NA16 prototype offered to RAAF by CAC) approved 11 November 1937
12 Avro Cadet order approved 18 November 1937, Overseas Indent 589. Air 2/1971 says as of 27 Oct 1938 deliveries expected in about a week, contract completed by end of year
10 Bolingbroke order approved 29 November 1937. Mercury VIII engines (Blenheim I) Overseas Indent 591. RAF Bolingbroke orders cancelled in December 1937.
(50) Bolingbroke order changed to 50 Beaufort in February 1938
40 Wirraway order (First) contract signed 15 March 1938 (In January 1937 the government indicated it would place the order, subject to the usual contract negotiations being successful.)
10 Avro Anson order approved 24 March or 5 April 1938, Overseas Indent 613.
40 Avro Anson ordered in 1938, arrived December 1938 to April 1939. Chartered, the RAAF to pay for freight from UK and then to return them (around 45,000 pounds), interim to cover the lack of Beauforts.
60 Wirraway order (Second) approved 29 September 1938. Contract Demand T.465
40 Beaufort order approved 31 August 1938, bringing the total on order to 90. Overseas Indent 657.
(20) Avro Cadet order approved 29 August 1938? Overseas Indent 656, cancelled, to Tiger Moth? Air 2/1791 says as of 26 October 1938 order had not been placed and it would take 6 to 8 months to build them.
20 Tiger Moth approved in Air Board Minute 21 Nov 1938, file RAAF 9/3/10. Britain to build the engines and fuselages, Australia the wings.
2 CAC Primary trainer prototypes, Wackett trainer, Approved 28 October 1938. Contract demand T.493
50 Hudson order, Overseas Indent/London order 680 approved 24 January 1939, but done in October or November 1938.
32 Wirraway order (Third) on 14 June 1939
18 Beaufighter order request to Britain 19 June 1939 Overseas Indent 712, part paid by reducing Beaufort order by 10 to 80 aircraft.
9 Sunderland Overseas Indent 707, approved 18 July 1939.

RAAF Aircraft inventory 1 September 1939, total 246 including reserves.
54 Demon
21 Seagull
82 Anson
7 Wirraway
21 Wapiti
32 Cadet "Avro Trainer"
29 Moth

The case for the pre war orders goes like this, the Demons were already in service, making them a known quantity, they could be supplied in a timely manner, they could be adapted as trainers and as replacements for the Wapiti tactical reconnaissance. The Ansons were a start on the maritime roles and could move to training when better types arrived. Extra trainers were needed and the Wirraway evaded US complications by being locally produced and not intended for overseas service. The long range maritime reconnaissance role was to be filled by the Sunderlands, their prompt delivery is quite a contrast to the time taken for the other pre war orders. Assuming delivery promises had been kept the RAAF would have had a Beaufort maritime strike force with Beaufighter escort all the way to the target located at long distance by Sunderlands. Their longer ranges compared to the single engine fighters would make it easier to move the forces around Australia.

The Empire air force program had two parts, offering lots of free trainers if the RAAF would pay for their use and the provision for nominal RAAF units in the RAF supplied with RAF aircraft plus at least some payment of wages, meaning outside of Australia there would usually be no higher officially RAAF unit than a squadron, though senior RAAF men might end up in command of larger units. Not what the pre war RAAF expected or wanted. The Australian Army deliberately created a full corps headquarters and associated corps troops to try and ensure its expeditionary force stayed together, one reason 3 RAAF squadron was sent overseas in 1940 and retained its RAAF number for the war.

The case for a new organisation to build the Beaufort is it gave Australia a second production source though geared to only license build (they did a lot of modifications), CAC could design and build, with De Havilland expanded to build Moths for training gave the country 3 sources and chances for any good De Havilland designs. The cost was the inevitable problems from inexperience which would only be a big problem if war came quickly, the plan was first machines delivered in 1940, production rising to 20 per month in September 1941 under peace time single shift conditions. There was no follow on order as of 1939, just like no follow on orders of Spitfires etc. when they started production, with the expectation the 2,000 HP fighters would take over "soon". Given the pace of aircraft development by end 1941 there would probably be a better design to shift to. The article says the Beaufort program start was "ill-informed and incoherent" partly due to the decision to go with the designed Taurus engine, what chance the Beaufort would be in Australian peace time production in 1940 with the delay due to the necessary design changes to use Twin Wasps? Producing Twin Wasp for Beauforts was suggested in a 29 September 1939 cable from Britain, given problems in ramping up Taurus production and starting the Australian line. On (2?) 18 October Australia said no, (24?) 23 October 1939 cable arrived from Britain requesting a change of mind. Then on (3?) 9 November advice there was plenty of Taurus available crossed the advice Australia had authorised twin wasp production on 31 October, but for Beauforts from number 51 onward.

Given the complexity of torpedoes the peace time requirements were best supplied from Britain, who in any case were planning to use the Australian built Beauforts in the Far East and so would have the relevant supplies.

CAC completed Wirraway number 132, the last of the pre war orders, in October 1940 and that was with accelerated production. For Australia to lay down a fighter production line in 1939/40 that could be useful as an air superiority aircraft in the two to three years it would take to hit peak production would mean the Spitfire and that would require imported engines given the speed of Merlin development.

The article does not mention the Brewster Bermuda expected to arrive in 1941 and replace the Wirraway in combat units, nor the Vengeance the order was amended to, with some optimistic delivery schedules. Also no one expected the Beaufighter to be air superiority, more night fighter and bomber destroyer. The Australians built 108 Merlin June 1947 to May 1952. Nene production started in December 1948

No one was willing to sell or at least base fighters in Australia 1939 to 1941, few were interested in shipping anything but unwanted, trainer and maritime reconnaissance types, there were far more other places that needed combat aircraft and with Singapore, Manila etc. expected to hold for some time, plenty of chances to send things later.

US Alternatives noted, the DB-7 used the Twin Wasp, the A-20 used the more powerful R-2600, ranges smaller than the Beaufort. DB-7 production began in October 1939, A-20 in December 1940, B-25 and B-26 production began in February 1941, the B-25 was considered quite good from the start, the B-26 not so. No mention of other alternatives like the Martin Maryland (September 1939), only the designs that later proved to be very useful. Easy now to see what the winners were.

The only reference found so far about RAAF Defiants is from British Cabinet document CAB/66/10/10, Secret W. P. (40) 279, 21st July, 1940, available online at the British Archives, talking about the RAAF after "Defiant Type", it was about a meeting called by the Australian representative to co-ordinate the Dominion requirements for aircraft from the United States, not Britain. The meeting was held in New York.

Deciding Australia needed and could obtain modern fighters 1939 to 1941 ignores the laws of supply and demand at the time, plus as of 1939 there was only 1 British or US fighter design in production that could stay current through the war. If war came the RAAF initially needed to be able to patrol large areas of ocean and help the army. RAF and RN doctrine meant maritime strike were torpedo bombers, the US had the Devastator. The distance from the rest of the world that hindered obtaining aircraft should allow adjustments to be made before the situation became too dangerous.

If no RAAF fighters were such an obvious problem to say mid 1940 then surely so was no aircraft carriers, submarines, tanks, heavy artillery etc. It is the dilemma of smaller countries, the bigger ones can usually build more and make improvements far faster, making your production insignificant and obsolete, but there will always be the time you really need things and no one else can supply them.
 
Perseus was also of the greater diameter, 55.3in vs. 51.5in for the Mercury. Add the 100 extra lbs for the engine weight, and all and any supposed gain of performance - both speed and RoC - is cancelled.

Early Perseus engines used the same S/C as the high-altitude Mk.X (that, as far as actual use, went nowhere), but with lower drive ratio. The Mk.Xa used the cropped S/C but with the higher drive ratio (see here).
The end result was similar, all the in-service marks being 'set' for the low-altitude power, but hopeless above 10000 ft. In taking advantage of the 100 oct fuel, Mercury was far better.
 
This does rather enforce my view that one needs to look for less aeroplane behind the engines one could get than hoping to find more powerful engines to put on the front of the airframe. To me the obvious is the Vickers Venom. The Mercury is less than 9cm wider than an Aquila, albeit noticeably heavier. The Pratt & Whitney Twin Wasp Junior is even narrower than an Aquila.
 
They built about 7(?) Aquila engines total, I don't think more than 2 had the same specification/standard of build. And they didn't work all that well. Combine that with the zoo show of the entire sleeve valve manufacturing in 1939/early 1940 and the chances of getting anything usable out of the Venom is about zero.
The Twins Wasp Junior was skinny. Most went around 1100lbs so power to weight was not good. Aside the The US navy the main customer were the French (they loved small 14 cylinder radial engines) and the British inherited a bunch of French contracts and a bunch were stuck in Miles Master trainers and few other odds and sods.
Most the later engines were good for 825hp at take-off and 825hp at 7200ft military power.
Now perhaps you can put less airplane behind the engine but if you want eight .303s, decent fuel, armor seat back, BP glass and even horse hair and glue on the fuel tanks you need more airplane than most of the 1936-39 planes offered without loosing a lot of performance.
 
The Venom was made for the same requirement F5/34 as the Gloster and seems to have done as well if not better on far less power. Not just popping a Mercury or Twin Wasp Junior on the front of course. The extra weight or diameter will need some reworking of the fuselage. The Aquila is, crudely, half a Taurus (or rather the other way round) and indeed is not going anywhere useful but the airframe was excellent so the suggested possible greater alternatives will enhance the performance. Not to mention the small span and excellent deck landing quality estimation may tempt the Royal Navy for the Nimrod replacement too. Vickers and Supermarine are too busy to make it but Glosters have the OTL Gladiator capacity which might be spared and Bouton Paul the Roc production line. The US Navy used single seat Spitfires to spot for naval shore bombardment so just perhaps the Venom could cover the Lysander's tasks with 2x250lb bombs too and do so more survivably. It would be easier to make an improved Venom than an improved Gloster which needs proper retractable wheels and more power which can, in period, only come at the expense of OTL Merlin engined types.

The issues of armament, armour and self sealing tanks apply to the Gloster F5/34 as much as to the Vickers F5/34. I agree that the Perseus gives little more than the Mercury which is both mature, admittedly at the end of it's development capacity and am aware that the Twin Wasp Junior is an unlikely choice strategically being of foreign manufacture.

Just stretching the AH rubber band a bit further, could it be suitable for Australian production with a licence built Mercury? We are looking at A6M/MC200 power here.
 
I suggested the 1535 because it was a 14 cylinder engine that was closer to the size and weight of the Mercury IX engine that ended up in the F.5 than the 1830, which was being suggested as a replacement for the Mercury, in the hands of the Aussie's.
Sure, the 1830 made more power, but it was also WAY heavier. Even though the 1535 doesn't make the power of the 1830, the potential is there to make more power than the Mercury and since that's the engine the plane ended up with, that's the benchmark I'm measuring by.
 
Had the Brits purchased the Reggiane Re.2000 I wonder what the Air Ministry and RAF boffins, pilots and ground crew would think of its Piaggio 14-cylinder radial engine. It's a standard pushrod engine (from the French Gnome-Rhône Mistral Major 14K) with no sleeve valve distractions or development delays.

At 38.6 L, 66.9 in long, 52.3 in wide and 1,433 lb (dry), the Piaggio P.XI is a long and heavy beast compared to the wider Perseus intended for the F5/34.
 
I like the idea of downsizing the plane when you don't have a more powerful engine.

About the same as the Bf 109. The smallest airframe for the most powerful engine you have.

If we look at it that way, the Gloster F5/34 is much too big. We need an analogy to Hawker's study before the Hurricane. That study resulted in, practically, a Fury monoplane (a biplane Fury, not the one from '44).

Now, analogously, we're talking about a monoplane Gladiator, of course with retractable landing gear, but still a steel structure/canvas (the first Hurricanes were like that) Mercury, with, say, 6 light machine guns. Maybe such a plane could be smaller and lighter and have better performance, better than Gladiator and comparable to the Hurricane/Spitfire at least until 1940? And still be ready on time?
There's an illustration of Hawker's project
Hawker Fury Monoplane Project of 1933

And I'm sure I've seen a model of a monoplane Gladiator on one of the what-iff scale models forums.
 
I like the idea of downsizing the plane when you don't have a more powerful engine.

About the same as the Bf 109. The smallest airframe for the most powerful engine you have.
And in 1934-35 the engine was 600-700hp Jumo 210 91.7 liters. The DB 601 was not fitted until 1938.
If we look at it that way, the Gloster F5/34 is much too big. We need an analogy to Hawker's study before the Hurricane. That study resulted in, practically, a Fury monoplane (a biplane Fury, not the one from '44).
And I believe the "fury monoplane" was supposed to use the RR Kestrel engine which was 21.2 liters.

The small fighter looses a lot of it's appeal once Air Ministries decide they want 20mm cannon or 6-8 RCMGs.
Both the small fighter and the large fighter need
One pilot, no savings there.
The same instrument panel, no savings there.
The same radio, no savings there.
Needs more planes to get the same armament (gun/ammo) into the battle area, so savings are very debatable.

Some planes were more amenable to upgrading than others. Larger engines were heavier, needed more fuel. Which increased take-off and landing speeds. Bigger engine helped with take-off, only hurt landing.

The real deathknell was in 1939-41 when most countries added 150-400lbs of armor, BP glass and protection for fuel fuel tanks.
Small airframes were going to show a bigger impact on performance than a large aircraft as the added weight's were a larger percentage even if the weights were actually the same.

Now if we go back to 1933 engine choice gets very problematic, The 830-840 hp Mercury does not exist, what is promised may be different.
Gladiator first flew in Sept 1934 with a 530 hp Mercury IV engine, which was soon to be replaced by a 645 hp Mercury VIS engine.
In 1937 when the production Gladiator Is started to show up they had 840hp Bristol Mercury IX engines.
Which version of Kestrel in which year?
And the British both screwed themselves and left the side door open for later improvements when they rejected that spawn of Satan, the variable pitch propeller
Meant they needed a big wing to get a Merlin and 8 guns out of a British airfield. Once they became devil worshipers and fitted 2 speed and CS props that shortened take-off runs by huge amounts, that meant they could add guns/ammo/armor/fuel (and protection) and still get out of small fields.
Part of the Gloster F5/34s short feild performance was due to the fact that in 1937-38 Gloster gave it a two pitch prop and it was being compared to planes with fixed pitch two blade props. Climb was still poor (so was a fixed pitch Hurricane) and they didn't have the power in the 9 cylinder radials to fix that.
 
Well, in the end, the Gloster F 5/34 flew with the Mercury (as did the Gladiator) and the Me 109 was mentioned because of the 600-700 hp Jumo and the Hawker Monoplane because of the Kestrel.

I cannot imagine the Gloster F5/34 by any stretch of the imagination as a fighter that would roam the skies of Germany in 1944.
Of those designs around 1935, only the Spitfire and the Me 109 (each for their own reasons) were in the front lines in 1945. The Hurricane faltered already in 1941, the P-36 as well, if we count the P-40 then in 1944?

We also know that the version of the small fighter with a weaker engine was not very successful (neither Russell nor Bell nor Italians).

So the only niche where I can imagine Gloster's radial fighter (because of the Hercules Centaurus story and the Hawker/Merlin factor) is as, well, in fact, the monoplane Gladiator. And right in that timeframe instead biplane Gladiator.
 
P-40 was behind the curve already by mid-1941? Certainly by mid-1942.
Reason why it was so had a lot to do with the reasons why the Spitfire and Bf 109 remained competitive until the end of the war - the (non) installation of the more modern & more powerful engines.

So the only niche where I can imagine Gloster's radial fighter (because of the Hercules Centaurus story and the Hawker/Merlin factor) is as, well, in fact, the monoplane Gladiator. And right in that timeframe instead biplane Gladiator.
Agreed.
 
If we split the P-40 into airframe and engine then the P-40 airframe was still on the curve in 1941-42-43. It may not have been on the leading edge but anything that wasn't P-51 was not on the leading edge.

The engine wasn't.
But the P-40F wasn't that far off most of it's adversaries in late 1942/early 43 at which point they stopped putting 1940/41 Merlins (single stage two speed) in them.
A better P-40 is a coulda/shoulda argument but a lot of it's opposition (planes with V-12 engines of 1100-1400hp) were smaller, carried less armament and often had less protection.
Speed wise the P-40 did pretty good for it's installed power for airplane of it's size and weight. P-40F was about 20mph faster at 20,000ft than a Hurricane II with the same engine (depends a little on the armament in the Hurricane II). P-40F was carrying about 25% more fuel internal than the Hurricane. Wasn't an escort fighter but that was a useful increase in range/endurance without drop tanks.
 
I cannot imagine the Gloster F5/34 by any stretch of the imagination as a fighter that would roam the skies of Germany in 1944.
I can't imagine it roaming the skies of Coastal France or Belgium in 1941.
neither Russell nor Bell nor Italians
The French had 4 other "light" fighters under development in 1939-40. All had problems. Many were fast but comparing to the MS 406 kind of tilts the playing field. They also used small wings which kept the drag down but didn't do much for their altitude performance. Speed in thrust vs drag so small (tiny) airplane looks good. But climb is power to weight and really low power vs low/medium weight means poor climb.
 
If we split the P-40 into airframe and engine then the P-40 airframe was still on the curve in 1941-42-43. It may not have been on the leading edge but anything that wasn't P-51 was not on the leading edge.
Pretty much.

The engine wasn't.
But the P-40F wasn't that far off most of it's adversaries in late 1942/early 43 at which point they stopped putting 1940/41 Merlins (single stage two speed) in them.
That time frame - late 1942/early 43 - is the problem. Adversaries of the P-40F were never powered by Merlins
The Fw 190 is finally able to do as advertised, the 109G (despite the engine being restricted) is not yet in the woods wrt. lumps and bumps, meaning that P-40F is in a bad position against them every bit as it was the Spitfire V, and there is no 2-stage Merlin on the P-40 to even up the odds. Not even the 2-stage V-1710.

A better P-40 is a coulda/shoulda argument but a lot of it's opposition (planes with V-12 engines of 1100-1400hp) were smaller, carried less armament and often had less protection.

There were also the fighters with radial engines that were a good match for the P-40, especially if the altitude band was high. Unfortunately, a P-40 with a V-1710 will have just over 900 HP at 18500 ft before late 1942, vs. the P-40F having ~1125 HP there (about same for the Spit V). The Bf 109 driver will have 1250 HP at the same altitude, and it will be piloting a much smaller and lighter A/C. Heaviest of the lot - Fw 190 - will have about 1350 HP (= 801C at 2700 rpm; a restricted 801D).

P-40 carried a lot of heavy guns and ammo, that does not mean that it carried greater firepower than the fighters that were armed with 2 cannons + 2 LMGs. Yes, a good deal of Japanese fighters carried barely any protection before 1943.

Come winter of 1942/43, the better V-1710s were barely picking up the slack (making about 950-1000 HP at 18500 ft), these engines were at least a full year behind the needs of the P-40s, P-39s and P-51s.
 
The P-40 was let down the Allison engine (or rather the supercharger of the Allison).

The P-40 was also blessed/cursed by the M2 .50 cal Browning. A lot of weight to haul around.
P-40s with 4 guns were fairly common.

Getting good performance numbers for the P-40Ls is hard. There were 670 (?) of the "stripper" P-40Ls.

None of the Merlin powered P-40s got the light weight radiators/oil coolers and wheels that the P-40Ns got.
The P-40Ls had one fuel tank taken out but still kept the electric starter and big battery that the P-40N-1 didn't have.


There were very, very few Italian fighter built with two 20mm and two 12.7mm machine guns.
Most were doing well to have two 12.7s and two 7.7mm guns and the Japanese were sort of in the same boat.
The Ki-61's with the Japanese Ho-5 20mm guns don't show up until early 1944. Granted the 388 planes with the German MG 151s show up earlier.
Ki-44s with 4 12.7mm guns have no firepower advantage.
The Ki. 84 is issued in the Spring of 1944 to it's first unit.

We read that the Ki 61 II KIA was an "outstanding interceptor" with a speed of 379mph at 19,645ft which is 9-15mph faster than 6 gun P-40F (Kittihawk II).
Of course the Ha 140 engine often did not work well. The Kittihawk II under test also managed 347mph at 30,000ft.

One does wonder what one of the Stripped P-40Ls would do using WEP power for climb?
Or if they could have gotten a few hundred pounds out of the plane by using aluminum radiators/oil coolers and deciding they didn't need to carry 1500-2500lbs worth of bomb/drop tanks under the plane?

Soviet fighters are fast but most of the Yak's are lacking in gun power. Might not be much worse than the four gun P-40 but not much better either.
Some sources (Curtiss factory?) say that the P-40Ls were good for 370mph at 20,000ft. Granted the range sucked but they still held 454 liters.
P-40Fs could hold 594 liters.

Most of the other contemporary fighters also could not do the other stuff (non air superiority ) that the P-40 could do.

The P-40 was not quite up to the P-51 but it is not the doddering antique it is sometimes made out to be. Throw 3/4 of ton of ballast into a Spitfire V and see how fast it is.
For an over 8000lb airplane the P-40 was doing very well for the power it had.
Why it got to over 8000lbs with that small engine (under 1400lbs?) is a different question
 
The P-40 was let down the Allison engine (or rather the supercharger of the Allison).
Yes, the S/C on the V-1710 was a weak spot of the otherwise good power section.
V-1710 was also a small engine, so the weakness of the S/C will be felt even more.

The P-40 was also blessed/cursed by the M2 .50 cal Browning. A lot of weight to haul around.
P-40s with 4 guns were fairly common.

Loosing two guns and ammo for these guns saves perhaps 1% of drag and ~3.5% or weight (300 lbs removed from 8400-8500 lbs all-up weight)? In the same time, for the P-40E and P-40K (main models in 1941-42), the power above 15000 ft was 25% down vs. a Merlin XX/45, and about 30% down vs. the DB 601E/down-rated 605A. Yes, the later V-1710s are a tad better, but still.
We can remove all the guns from the P-40, and it will still be lacking vs. the European opposition.
Vs. the Japanese opposition, the power/weight ratio of a P-40 is also bad.

We can recall that the P-40s of 1941-43, bar the lightened/stripper models, were about as heavy as the Fw 190s of that time, but without the power to back up that weight.


Main Japanese fighter the US Army aviator will deal with was the Zero. Two cannons aboard.
Would we prefer to be in a Ki-44-II or in a P-40? I'd bet on the Japanese fighter.
(the Ha 109 would've been a great engine for a P-40)
Main Axis fighter the P-40 will be dealing with was the Bf 109. At least one cannon, and even if two extra cannons are installed, the P-40 is still the one with worse speed and climb (apart from the low level flight & combat).
Italian fighters (mostly MC.202?) vs. the P-40 - about the same thing as the P-51B vs. the Fw 190? Extra firepower is beaten by enemy extra performance, and the MC.202 was well regarded by the Allied pilots.

Then we have the Fw 190 threat, and the fact that the Spitfires were flying top cover for the P-40s - kinda shows the tier where the P-40 belonged. That P-40 was not used against Germans in ETO speaks volumes.


For the Japanese conditions of the time, Ki-61 with the Ha 140 was probably an outstanding fighters. From the Anglo-American perspective, it was badly behind the curve. So I'd consume the "outstanding interceptor" phrase together with the truckload of salt


Unfortunately, WEP is of no help above 12 - 15K feet
Hopefully, the speed tests should've been done with a clean fighter at 1st.


The 370 mph figure is believable for me; the fully-gunned P-40F was at 360+ mph. Allies would've need a 400 mph fighter by the time P-40L arrived, though, and they were getting them in service.

Most of the other contemporary fighters also could not do the other stuff (non air superiority ) that the P-40 could do.

From a fighter aircraft, people were expecting it to be very good/excellent in it's primary role. When a fighter was relegated to the fighter-bomber duties, that was a good sign that it was found lacking in it's primary role, with other types being better.

For an over 8000lb airplane the P-40 was doing very well for the power it had.
Why it got to over 8000lbs with that small engine (under 1400lbs?) is a different question

Agreed all the way.
 
A lot of good points, but a few quibbles
V-1710 was also a small engine, so the weakness of the S/C will be felt even more.
We keep falling into the displacement trap. It is possible to compensate for small displacement with RPM at the fundamental stage (initial design/development).
Just for fun a few simple numbers on liters per minute.
Allison/3000rpm....................42,000l/m
H-S 12Y/2400rpm..................43,200l/m
Jumo 211/2500rpm..............43,750l/m
DB 601A/2400rpm................40,680l/m
DB 601E/2600rpm.................44,070l/m
DB 605 AM/2800rpm...........49,980l/m
Merlin/3000rpm.....................40,500/m

Now, as we all know, it is nowhere near that simple as we have not taken into account boost pressure, valve duration/overlap and valve/port size etc.
The HS 12Y does show a pitfall. It was 36 liters which makes it the largest engine (displacement wise) in the list. It is also the tied for last place in rpm with the early DB 601 and it is, by the far, the lightest engine on this list. This meant it could not stand up to making high power without breaking.
Once the engine designers decide on a formula (large displacement/low rpm vs small displacement/high rpm) for a give power at in a certain weight range they are sort of stuck with it. Given better fuels they can increase compression ratio or boost, play with the valves, use a different supercharger and so on. Changing the RPM gets a lot harder. Germans did it, not easy and it may have hurt durability/engine life.
The Allison was in ball park with the others until the DB 605 showed up. It was the supercharger that could not flow enough air.

Vs. the Japanese opposition, the power/weight ratio of a P-40 is also bad.
Very true. Weight is rarely a good thing
Unfortunately, WEP is of no help above 12 - 15K feet
It isn't. But if you are trying to compare climbs to 15,000 or 20,000ft and light plane X is getting to 20,000ft 2-4 minutes quicker than fatty plane Y when plane Y is using "standard" power then WEP can equalize things a bit for the "enemy bombers spotted 9 minutes away from the air base" scenarios If you have 20 minutes warning then the slow climb aircraft can be at combat altitude when the raid gets there (F4F-4s couldn't climb for crap)
This does vary a bit from Air Force to Air Force and over time. In 1942 and some of 1943 the US needed general purpose planes. They didn't have the men (flight crews/ground crews) and the number/size air bases they needed in some locations for specialized aircraft. Unless you consider using P-40s as 'top cover' for P-39s
Nowhere near enough P-38s to do all the top cover missions, which is why they used reverse lend lease Spitfires in NA. P-40Fs also sometimes flew top cover for the Allison P-40s and P-39s.
Merlin powered P-40s made up just about 33% of the P-40s built from the summer of 1940 to the end of June of 1943. The vast majority were used in NA and Italy.
Such was the speed of development (and combat) that a lot of manufacturing allocations (contracts) were placed for the Merlin powered P-40s months before they got into combat and a lot of the contracts were curtailed or not extended (they wanted the Merlin's for other aircraft) within a few months of the Merlin powered P-40s combat debut. They had no time to develop any specialized versions aside from pulling out a few guns and a fuel tank. The Contract for the P-40Ls was placed two weeks before the first batch of P-40Fs were placed on board the aircraft carrier Ranger to be sailed to Africa. It takes two months to sail over, fly off the carrier and fly across and up Africa into Palestine and placed in service (July 31st 1942). It is all well and good to say that you want interceptors at the end of May 1942 but if the planes (already built) take 2 months to get to combat theater you better have guessed right.
P-40F may not have been as good as was hoped, but the last part of 1942 they only other planes they had were Allison P-40s, P-39s and under a 150 P-38s a month.

The P-40 wasn't getting respect at the time, the planners wanted the "new" gee-whiz aircraft instead of the old P-40. P-40s were ordered when the new gee-whiz aircraft fell on their faces. The Army ordered the P-40K, L and Ms on June 11th 1942 when they canceled the Curtiss P-60A

Which was not performing as promised and was months away from going into production. But most of the R&D was going into other new projects and not updating the existing P-40. Army was still pushing Allison to make turbo charged engines instead of even two speed single stage engines. They were trying to skip over the lower fruit and jump for the high branches.
 

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