Comparison of the Gloster F.5/34 and the Mitsubishi A6M2.

The Gloster shows up in a number of "what if's" but it needed development, mainly in a new engine or else it gets rather distorted.

The two planes are remarkably similar in size, even the wing area is only off by about 5% on 230-241sq ft wings.
Loaded weight is within a few hundred pounds (if the Zero is not carrying a drop tank).
Weight of armament is close. One 20mm is only a little lighter that 3 Brownings.

Two main problems are we have to believe the published speed for the F.5/34 which certainly seems high but that has been gone over in other threads.

The other problem, and using a lot of hindsight, The F.5/34 has nowhere to go engine wise.
The Prototype used a Mercury IX engine that was rated at 725hp for take-off and 840hp at 14,000ft which helped with the speed, it also explains the 11 minutes to 20,000ft even using a two pitch prop (ok two pitch props don't work well in climb). Plan was to change to the Perseus engine and there were two choices. The Perseus X (fully supercharged ) with a take off rating of 750hp and 880hp at 15,500ft. A useful increase over the Mercury but not exactly earth shaking (or sky ripping).
However the Zero (unknown in the west at this time) was flying with a Mitsubishi Zuisei engine of 780hp for take-off and 875hp at 11,800ft. The Japanese were not happy. After two prototypes they switched to the Sakae 12 engine that gave 940hp for take-off and 950hp at 13,780ft
The F.5/34 had several choices (in "what if" land), switch to the Perseus XI/XII medium supercharged engine and get 830hp for take-off (used in the Blackburn Skua and Roc and many Bothas) and 905 hp at altitude but altitude was only 6500ft. Might be OK (maybe for a British Naval fighter of 1938-40 but it does really give up the higher (over 10,000ft) altitudes. Perseus weighs 465kg. The Sakae 12 was about 530kg.
with hindsight we know the Perseus really didn't go any further. They had the Taurus and in 1938/39 they didn't know how bad that was going to get.
It also weighed 590kg and even running on 100/130 fuel it maxed out at 1130hp at 3500f. Now take off about 2% for every additional 1000ft of altitude.
Things are not looking good in the middle teens.
Last gasp, Hail Mary pass. Stuff the Hercules engine in. Except..................................
Weight 835kg, Power in early form was 1325hp T-O and 1375hp at an ear popping, nose bleeding 4000ft. Fixed in the two speed Hercules III version.
Now go back and look at the original Mercury engine used in the F.5/34 prototype. 454kg. sticking in a Hercules adds 380kg and you still need a bigger prop (and more fuel). Increasing the powerplant weight by about 83% is going to distort the whole plane. You might get there but there is a lot of stuff that has to be changed.
The Kinsei engine used in the last two A6M8 prototypes might have gone to around 675-680kg?

A bit long winded but there doesn't seem to be any practical way to get the F5/34 into the performance envelope of the A6M2 with the existing engines or with anything in the logical pipeline. The Mercury, Perseus and Taurus were all 24.9-25.4 liter engines and the Sakae engine was a 27.9 liter engine.
The P&W R-1830 was a 30 liter engine.
even if they had ordered the F.5/34 into production instead of the Roc and planned to swipe Taurus engines from the Beaufort (by sword point?) the problems with the Taurus engines would have soon stopped that.

Shove the Merlin on it and it becomes far more useful.

I am not going to wade into the engine problem as that is WAY over my head, but the rearward retracting gear would need to be tossed out, and perhaps the 1930's style thick airfoil cross section as well.

The Mercury and Perseus were adequate if you can put less aeroplane on the back so that could be the Vickers Venom as a base. An alternative power in the class was the Pratt and Whitney Twin Wasp Junior. The Perseus would be common to the Skua both for commonality and a reserve source of engines when the Skua leaves service.

Yes I do understand that the engines are heavier than the Aquila and one needs to allow extra weight for self sealing tanks and armour so it is not a bolt on job but an enlargement. The Venom was rated as a good carrier option from the handling point of view.

Keep the engine and throw away the aeroplane and swap in a new one.

The Perseus did very well on the civil S.30 Short Empire, where the procedures and operating limitations were closely followed.
Put in military operation, they did rather poorly. I read that the Royal Navy procedure for one of their aeroplanes missed the step of opening the drain to the junk head prior to operation, resulting in cylinder failures.
Similar to how the Allison V1710 was an excellent engine for many services, but for the RAAF in the F-4 was an absolute dog. Not every bad engine was 100% the fault of the engine.

What about Bristol Pegasus XVIII? 885hp at 2600 rpm at 15,500 ft with 5 1/2 lbs boost on 87 octane. 100 octane gets you 965hp at 13,000. Weight of 535.7kg. Diameter, of course, is going to be about 93mm more than the Mercury.

Hardrada55 said:

What about Bristol Pegasus XVIII? 885hp at 2600 rpm at 15,500 ft with 5 1/2 lbs boost on 87 octane. 100 octane gets you 965hp at 13,000. Weight of 535.7kg. Diameter, of course, is going to be about 93mm more than the Mercury.

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A far better choice than the Perseus.
But again, going V12 - as Curtiss did with P-36 to P-40, as well as the Italians with their fighters - was probably the best way to go.

They could have stayed with the Mercury, later versions, as fitted to the Blenheim i.e. the Mercury XV pushed it up to 905h.p.
Or, go for the British imperial adaptions of a French engine the Alvis Pericles more like a 1,000 h.p.
Mind you, apart from the Zero, there is another more comparable aircraft that was produced, and did see service - the Italian Macchi MC200 - 840h.p. licensed built Mercury I believe.
The big problem with the Gloster aircraft, was not having a dedicated team to enable it to be shown at the 1936 Hendon Air Show = export orders and bye bye Glad!!

One wonder what impact it would have had if Bristol hadn't drank the sleeve valve cool-aid? While the Hercules eventually became a reliable and apparently well-regarded engine, sorting it out took a long time, and the Centaurus missed the war entirely. Without the sleeve-valve side-step they might have had a poppet valve Hercules years earlier, and the Centaurus would likely have seen service during WWII. As well as a decent intermediate-sized engine, like a poppet valve Taurus, that could have been a nice powerplant for this Gloster F.5/34. Oh well..

merlin said:

They could have stayed with the Mercury, later versions, as fitted to the Blenheim i.e. the Mercury XV pushed it up to 905h.p.
Or, go for the British imperial adaptions of a French engine the Alvis Pericles more like a 1,000 h.p.

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The earlier the people at Gloster look towards the Merlin and forget the radials good for 1000+- HP at low altitudes, the better.
(in the fashion that Curtiss did with P-36 when it became P-40, or the Italians when they started installing the DB 601 on their fighters)
Merlin III was making 1300 HP at these altitudes, while having a lower drag when installed, and much better exhaust thrust.

merlin said:

Mind you, apart from the Zero, there is another more comparable aircraft that was produced, and did see service - the Italian Macchi MC200 - 840h.p. licensed built Mercury I believe.

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Fiat radials had nothing in common with Bristol radials, genetics-wise.
BTW - British don't need yet another fighter that cannot make 500 km/h, with Hurricane in production.

merlin said:

The big problem with the Gloster aircraft, was not having a dedicated team to enable it to be shown at the 1936 Hendon Air Show = export orders and bye bye Glad!!

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The big problem with Gloster aircraft was thinking that biplane fighters are just awesome even though the 1930s arrived years ago. They were 'helped' in that regard by the Air Ministry and probably the 'parent company (Hawker).

z42 said:

One wonder what impact it would have had if Bristol hadn't drank the sleeve valve cool-aid? While the Hercules eventually became a reliable and apparently well-regarded engine, sorting it out took a long time, and the Centaurus missed the war entirely. Without the sleeve-valve side-step they might have had a poppet valve Hercules years earlier, and the Centaurus would likely have seen service during WWII. As well as a decent intermediate-sized engine, like a poppet valve Taurus, that could have been a nice powerplant for this Gloster F.5/34. Oh well..

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The issue with machining the sleeves for mass production was solved in March 1938 (1). I am not privy to Bristols production report's, but if the sleeve mass production is sorted by 1938, I expect that all delays subsequent to this were not (or only indirectly) related to the valve operating mechanism. Thus poppet valve Bristol radials would likely have only had a very minor schedule improvement.

(1) The Bristol Sleeve Valve Aero Engines, Patrick Hassell, Rolls-Royce Heritage Trust, p 122 of "The Piston Engine Revolution".

Simon Thomas said:

The issue with machining the sleeves for mass production was solved in March 1938 (1). I am not privy to Bristols production report's, but if the sleeve mass production is sorted by 1938, I expect that all delays subsequent to this were not (or only indirectly) related to the valve operating mechanism. Thus poppet valve Bristol radials would likely have only had a very minor schedule improvement.

(1) The Bristol Sleeve Valve Aero Engines, Patrick Hassell, Rolls-Royce Heritage Trust, p 122 of "The Piston Engine Revolution".

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I'm sure you're correct but I just realized what your avatar is for the first time. Cool!
(Ancient eyes.)

Shortround6 said:

A bit long winded but there doesn't seem to be any practical way to get the F5/34 into the performance envelope of the A6M2 with the existing engines or with anything in the logical pipeline.

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Strip out the F5/34 to get the empty weight down from 4,190 lb to something closer to the A6M's 3,704 lb (for comparison, Gloster's own Gladiator had an empty weight of 3,217 lb) or the 3,872 lb Bf 109D, while tweaking the best out of the Perseus (the later Perseus 100 produced 1,200 hp) and reducing drag (start with flush main and rear undercarriage and aerodynamically-clean exhaust ports) and we have a starting point. Look at the underside of this thing compared to the A6M below, there's a ton of unnecessary drag here.



The biggest barrier to seeing a better F5/34 is that Hawker Siddeley acquired Gloster and shut down the F5 program in preference for Camm's Hawker Hurricane. As such, with the F5's cancellation the Group would not field an all-metal single engined fighter until the Typhoon.

I have a what-if on my mind where upon his resignation Hawker Siddeley gives the F5/34 rights to its designer, Henry Folland (of Gnat fame). Folland then takes the prototypes and blueprints to CC&F in Fort William, Canada, where the F5/34 instead of the Gregor FDB-1 is produced using the P&W R-1830 Twin Wasp. Folland and CC&F's Elsie MacGill focus on improving the design and setting up Canadian production for both the RAF and FAA, while offering the F5/34 in CKD to CAC and HAL for Empire-wide production. By Autumn 1941 two dozen squadrons of F5/34 are operational over Malaya.

In the end, to me, the better Zero-like fighter to come out of Europe is the Caproni Vizzola F.5.



Interestingly, we won't see an Allied single-engine radial-powered fighter with the Zero's full visibility canopy until well into the war with the likes of the Republic P-47D, Centaurus-powered Hawker Tempest and Grumman Bearcat.

tomo pauk said:

Shove the Merlin on it and it becomes far more useful.

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No chance. Gloster's new owners at Hawker-Siddeley already have the Hurricane, and the latter being Camm's baby means the Gloster is not getting a Merlin.

Admiral Beez said:

Strip out the F5/34 to get the empty weight down from 4,190 lb to something closer to the A6M's 3,704 lb (for comparison, Gloster's own Gladiator had an empty weight of 3,217 lb) or the 3,872 lb Bf 109D, while tweaking the best out of the Perseus (the later Perseus 100 produced 1,200 hp) and reducing drag (start with flush main and rear undercarriage and aerodynamically-clean exhaust ports) and we have a starting point. Look at the underside of this thing compared to the A6M below, there's a ton of unnecessary drag here.

View attachment 796358 View attachment 796359

The biggest barrier to seeing a better F5/34 is that Hawker Siddeley acquired Gloster and shut down the F5 program in preference for Camm's Hawker Hurricane. As such, with the F5's cancellation the Group would not field an all-metal single engined fighter until the Typhoon.

I have a what-if on my mind where upon his resignation Hawker Siddeley gives the F5/34 rights to its designer, Henry Folland (of Gnat fame). Folland then takes the prototypes and blueprints to CC&F in Fort William, Canada, where the F5/34 instead of the Gregor FDB-1 is produced using the P&W R-1830 Twin Wasp. Folland and CC&F's Elsie MacGill focus on improving the design and setting up Canadian production for both the RAF and FAA, while offering the F5/34 in CKD to CAC and HAL for Empire-wide production. By Autumn 1941 two dozen squadrons of F5/34 are operational over Malaya.

In the end, to me, the better Zero-like fighter to come out of Europe is the Caproni Vizzola F.5.

View attachment 796417 View attachment 796495

Interestingly, we won't see an Allied single-engine radial-powered fighter with the Zero's full visibility canopy until well into the war with the likes of the Republic P-47D, Centaurus-powered Hawker Tempest and Grumman Bearcat.

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Hi
So the A6M was a more advanced design than the F.5/34, no kidding! The (much delayed, due to other work) first flight of the F.5/34 was in December 1937, built to a 1934 requirement. The A6M first flight in April 1939, built to a 1937 requirement, considering the progress in aviation technology during the late 1930s it would be no surprise that it was better than the Gloster design. Of course when the F.5/34 flew it was totally superior to the A6M as the latter did not exist. As the F.5/34 did not offer much over the existing production fighters, the Hurricane and Spitfire, and had less scope for improvement what would be the point of building it 'Empire' wide. If the resources and capabilities were available pre-war to build more fighters (and their engines) then surely the Hurricane (as happened) and Spitfire extra production would be the way to go?

Mike

Admiral Beez said:

while tweaking the best out of the Perseus (the later Perseus 100 produced 1,200 hp)

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The Perseus 100 may have been vapor ware. No picture of it seems to exist (and that was in Feb 1946?)
It seems to have been 1/2 of the Centaurus? at least it used the same stroke as the Centaurus.
It gained about 200lbs in weight, it gained about 3in in diameter, if it existed at all.
So far it doesn't seem to have actually flown, in anything, even if it actually ran on a test stand.

MikeMeech said:

So the A6M was a more advanced design than the F.5/34, no kidding!

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The A6M was not more advanced than the F5/34, but it was more aerodynamically efficient and lighter.

Admiral Beez said:

In the end, to me, the better Zero-like fighter to come out of Europe is the Caproni Vizzola F.5.

View attachment 796417 View attachment 796495

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What are these blisters around the cowling for, BTW?

Interestingly, we won't see an Allied single-engine radial-powered fighter with the Zero's full visibility canopy until well into the war with the likes of the Republic P-47D, Centaurus-powered Hawker Tempest and Grumman Bearcat.

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It is slightly mystifying, really. Surely already WWI taught air forces that keeping your head on a swivel was key to pilot survival? Even if the technology to make 'proper' full bubble canopies like the late-war Allied aircraft was a somewhat later development, surely a Zero-style 'greenhouse' canopy was easily doable by all the major aircraft building nations.

z42 said:

What are these blisters around the cowling for, BTW?

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On the Italian? I believe those are direct exhaust ports coming right off the cylinder head. Most radials have exhaust manifolds directing gases to one exhaust pipe on each side of the motor. So, some streamlining needed there too.

z42 said:

It is slightly mystifying, really. Surely already WWI taught air forces that keeping your head on a swivel was key to pilot survival? Even if the technology to make 'proper' full bubble canopies like the late-war Allied aircraft was a somewhat later development, surely a Zero-style 'greenhouse' canopy was easily doable by all the major aircraft building nations.

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To be fair to the Allies, there were several mid-war inline-powered fighters with all round visibility, including the P-51D, later Spitfires and the Yak-9.

Admiral Beez said:

On the Italian? I believe those are direct exhaust ports coming right off the cylinder head. Most radials have exhaust manifolds directing gases to one exhaust pipe on each side of the motor. So, some streamlining needed there too.

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Yes, I meant the Caproni F.5 images you showed. I suspected they'd be some kind of exhaust stubs, but if one looks at the second picture from slightly the rear of the plane, it seems there's no hole for the exhaust pipe, those blisters seem to smoothly merge into the cowling at the rear? Then again, I'm not seeing any other kind of exhaust pipe there either..?

To be fair to the Allies, there were several mid-war inline-powered fighters with all round visibility, including the P-51D, later Spitfires and the Yak-9.

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I was thinking more generally of the 1930'ies fighters with enclosed cockpits being developed, almost none(?) of which had bubble/greenhouse style canopies. Like Hurricane, Spitfire, P-36/40, indeed P-51A/B, Bf 109, etc.