Build an improved Gloster F5/34

[fastmongrel]

Spitfire might end up with Merlin XX in the nose in time of BoB and later,

What's a Spitfire. Was that the Supermarine fighter proposal that never got an order.

 

[Shortround6]

I will stand corrected on the figures for the Italian planes.

The Gloster was pretty much the size of the RE 2000 and larger than the MC 200, they do make good benchmarks. But the RE 2001 shows that while you could make a "better" F5/34 we are getting into why bother. It is being suggested as a Spitfire replacement, not a Hurricane replacement. The smaller MC 200 does show excellent performance but it's smaller size represents a total redo of the F5/34 and not just an engine change. It also had some limited room for growth.

The redesigned F5 needs to be in service at the latest spring 1940

Here is a real problem. We need to define "needs to be in service"
Spitfire was "in Service" in June of 1938 and 9 squadrons were fully equipped by Sept of 1939.
Perhaps the modified F5/34 is easier to build than the Spitfire and more can be built in less time. But to have anywhere near 19 squadrons in the summer of 1940 it needs to be in production and being issued to first squadrons sometime in late 1938 or very early 1939.

 

[fastmongrel]

Here is a real problem. We need to define "needs to be in service"
Spitfire was "in Service" in June of 1938 and 9 squadrons were fully equipped by Sept of 1939.
Perhaps the modified F5/34 is easier to build than the Spitfire and more can be built in less time. But to have anywhere near 19 squadrons in the summer of 1940 it needs to be in production and being issued to first squadrons sometime in late 1938 or very early 1939.

I was thinking that the Hurricane did all the heavy lifting during the BoB with the F5 coming into use much like the Spitfire MkII was introduced.

 

[tomo pauk]

The Gloster was pretty much the size of the RE 2000 and larger than the MC 200, they do make good benchmarks. But the RE 2001 shows that while you could make a "better" F5/34 we are getting into why bother. It is being suggested as a Spitfire replacement, not a Hurricane replacement. The smaller MC 200 does show excellent performance but it's smaller size represents a total redo of the F5/34 and not just an engine change. It also had some limited room for growth.

I haven't suggested that Gloster's fighter is a Spitfire replacement, but rather the Hurricane replacement, at least on Gloster's production lines and for 1939-41. This also covers the 'why bother' part - it can receive Merlin XII for the BoB while still doing okay, with Spitfire getting the Merlin XX to make it into an over-performer.

As for the 'wing surgery' - yes, it will be needed if we want it to remain competitive when powered by 1-stage Merlins. Perhaps have George Carter do the job, his E.28/39 have had fairly thin wing? We would probably want a wing of 180-190 sq ft of area, though. Radiators better than 'beard' radiators will also play a part in streamlining.

 

[Shortround6]

You need wing surgery (or at least landing gear surgery) to be competitive in the first place. Carter may have designed/used a thin wing but he didn't try to put much in it. And he was working 1-2 years after the Typhoon was designed. Chances of getting any wing designed in mid to late 1939 into production in early to mid 1940??? about zero.
Could Britain afford the disruption in production trying to change from the Hurricane to the F5/34 would have caused? Hundreds fewer fighters in early-mid 1940?

 

[Admiral Beez]

So starting with the F5/34 what do we need to get it up to or near 109E standard.

The engine. It has to be a Merlin nothing else comes close unless Daimler Benz suddenly start exports.

Once you change to a liquid cooled engine with radiator, coolant, plumbing and streamlined cowling you've basically got a new, but similar aircraft, akin to P-36 to P-40.

IMO, install the intended Perseus engine and have the backward retracting undercariage turn flush like the P-40 (or redesigned Hurricane-like as you suggest) and you're all set. One benefit of the Gloster is that it doesn't need a rare/in-demand Merlin. If the Perseus can reach its 1200 hp before the war it will be on par with the competition.

But what happens in 1940-41? The Perseus won't cut it then, and the F5/34 is not designed for the much heavier and larger Hercules. Unless a >1,400 hp radial can be found to fit, the Gloster is at a dead end.

 

[Admiral Beez]

I haven't suggested that Gloster's fighter is a Spitfire replacement, but rather the Hurricane replacement, at least on Gloster's production lines and for 1939-41.

I'd keep all three. Keep the Gloster, but drop the Defiant and Whirlwind programs. Both cancelations free up RR engine production, with the latter eliminating the Peregrine's distraction from the superlative Merlin.

The Gloster F5/34 would have been Hawker Siddeley's first all-metal single seat fighter. Years before Camm's Typhoon. One challenge would be that Henry Folland, the Gloster's designer resigned after Hawker acquired the firm in 1937. We'd need Camm to entice Folland to stay, or have another designer finish the job.

The Bristol Perseus was not used in anything that demanded a fighter's performance, though the Skua and Roc would have welcomed it. Put this engine in the Gloster and Bristol may be pressed to find another two hundred horsepower or so. The larger and heavier Hercules won't work, akin to putting a P&W R-2800 into a F4F Wildcat.

Get it sorted and the Gloster can be seen as having four uses. First, a backup in case Merlin production is stressed; second as an empire fighter for use overseas (though the sleeve valves won't make maintenance easy); third for license production using Curtiss or P&W engines in Australia or Canada (like how both produced US-engined Bristol bombers); lastly, with folding wings, as a successor or substitute to the Fulmar in FAA service.

AU_Solarium_Fleet_Air_Arm

 

[Admiral Beez]

The two fighters that showed what radials could do were the A6M Zero (960hp Sakae engine) which entered service June 1940 only 2 month before the Me 109F1 August 1940 and the Fw 190A in August 1941.

You don't consider the Ki-43, Grumman F4F and Re.2000/2002 good early radial fighters?

 

[Shortround6]

The Bristol Perseus was not used in anything that demanded a fighter's performance, though the Skua and Roc would have welcomed it. Put this engine in the Gloster and Bristol may be pressed to find another two hundred horsepower or so. The larger and heavier Hercules won't work, akin to putting a P&W R-2800 into a F4F Wildcat.

Actually the Skua and the Roc used the Perseus engine.

You could "press" Bristol for more power from the Perseus, you weren't going to to get it. The Perseus was a 1520 cu in engine. It was just too small, do NOT compare to liquid cooled engines but to air cooled engines. The Perseus (and Mercury) were 83% as large as the Cyclone and Twin Wasp.

In fact the Perseus used 9 cylinders of the exact bore and stoke that the Hercules used. At any given stage of development of the Hercules you could have mounted 9 cylinders on a Perseus crankcase and gotten about 64% of the power of the Hercules (assuming you had the supercharger figured out).

Do NOT be confused by the mention of the Perseus 100 engine in Wikipedia or other places. The Perseus 100 used cylinders from a Centaurus engine (longer stroke) and was a much, much later "development" or pipe dream of the Bristol company. A way to get back into the post-war aviation market using an ll00-1200hp 9 cylinder engine that was newer than the Pegasus. There is no record that the Perseus 100 ever flew in anything (even a test bed aircraft).
Specifications were announced/published which included using 100/130 fuel and 9.5lb boost which was high for an early war Bristol engine.
Specification also claims an 200lb weight gain from the earlier Perseus engine/s.
It was not a path or possibility pre war or early war.

And here is part of the problem with using other engines. The Mercury engine was just under 1100lbs, the Perseus was just over 1100lbs. The higher powered Cyclones (100-1200hp) were heading for 1300lbs and the Twin Wasp was 1400-1500lbs with a two speed supercharger, two stage supercharger was over 1500lbs.

The Taurus was never developed to make the needed power for a number of reasons.

 

[Admiral Beez]

And here is part of the problem with using other engines. The Mercury engine was just under 1100lbs, the Perseus was just over 1100lbs. The higher powered Cyclones (100-1200hp) were heading for 1300lbs and the Twin Wasp was 1400-1500lbs with a two speed supercharger, two stage supercharger was over 1500lbs.

I'd ideally want to separate the Gloster F5/34 from any Bristol engine. Folland departed Gloster in 1937 when it was acquired by Hawker. Let's have Gloster sell its drawings, design and prototype for the F5/34 to CC&F or in Canada or CAC in Australia.

Next, we must modify the design to accept engines over 1,500 lbs, as you advise above. And to be relevant, we must have hundreds of these aircraft, presumably called the Folland Falcon (?) in Empire service before the end of 1940. So, that's no Hurricanes at CC&F, I assume. As a Hurricane replacement, the Folland F5 would look good in Russian colours I bet.

 

[Shortround6]

I'd ideally want to separate the Gloster F5/34 from any Bristol engine. Folland departed Gloster in 1937 when it was acquired by Hawker. Let's have Gloster sell its drawings, design and prototype for the F5/34 to CC&F or in Canada or CAC in Australia.

Next, we must modify the design to accept engines over 1,500 lbs, as you advise above. And to be relevant, we must have hundreds of these aircraft, presumably called the Folland Falcon (?) in Empire service before the end of 1940. So, that's no Hurricanes at CC&F, I assume. As a Hurricane replacement, the Folland F5 would look good in Russian colours I bet.

Then you need a much heavier investment in industry in either Australia or Canada or both than what existed in either Canada or Australia in in 1937 or 1938 or the beginning of 1939.
As has been explained many times, CC&F in Canada was not a real aircraft factory at this time. They had built the Grumman Goblins but the Grumman aircraft had been supplied as kits. Grumman sent the fuselages in crates and Brewster sent the wings and tail surfaces in crates, Wright sent the engines, and so on down the list.

The Australians are trying to figure out how to make the Wirrarway, They knew that all metal aircraft exist, The problem is building them without taking even more time than tooling up for the NA-16 and having to buy even more tooling.

Now go back and see exactly which engines were available when, as what was available in 1937 or 1938 or 1939 and each year was different unless you are using a time machine.

Are you buying the engines from the US ( without Bristol that is your only real hope) or are your going to try build an engine factory in either Australia or Canada?

in 1938/39 P & W expanded their floor space by 4 times so there was not only no spare capacity at P&W's home factory but P & W was buying up all kinds of machine tools for themselves.

For P & W the R-1830 went through a number of changes in 1937-40 so be careful when you start something. P&W didn't actually deliver any two speed engines until 1940. That is two speed, not two stage. They were actually flying two stage engines before they flew two speed engines.
Because both P & W and Wright were biased towards commercial engines (and because US supercharger design was not very good) the two US radials peaked at under 10,000ft in the single speed models. Wright was earlier at offering two speed superchargers but that was more to give high take-off power than to really raise ceiling much.

As a rough time line Wright introduced the the later R-1820s as follows. These are Take-off powers. They also require either 91 octane fuel or 100 octane fuel (US 100 octane not British 100 octane BoB fuel). Also note that the 3 engines are NOT, repeat, NOT interchangeable in anyway, shape or form. They use different crankcases, different crankshafts, different head castings and a lot of other different parts. Building an Australian factory in 1935/36 just means you have to throw out a lot of stuff in 1937 and start over. Same with tooling up to to make the 1100hp version much before Early 1939.

1000hp (or developed to to make 1000hp) April 1935.
1100hp (or developed to to make 1100hp) Jan 1937.
1200hp (or developed to to make 1200hp) March 1939.

The 1200hp engine used in the Last Buffalos (F2A-2 and F2A-3s) didn't show up until late 1940 and will give you 1000hp at 14,200ft in high gear using US 100 octane fuel and about 900hp at 15,200ft using US 91 octane fuel.

You can get 1200hp out a single speed P & W R-1830 but you need 100 octane fuel to do it and even at 2700rpm power drops to 1150hp at 5,000ft , 975hp at 10,000ft and 810hp at 15,000ft.
Mercury using 87 octane will give you 840hp at 14,000ft. Problem with the Mercury engine is that with 87 octane fuel you only have 725hp for take-off and not 1200hp.

Of course with 87-91 octane fuel the R-1830 is only going to give you 1050-1100hp for take off depending on when you build it. The older ones (1937-38) were lucky to give you 900hp for take-off even with 87 octane fuel.
Depending on when they were built R-1830s tended to run (with exceptions) at 2450rpm for take-off, 2550rpm for take-off, and 2700rpm for take off. They also gained several hundred pounds.

So yeah, if you take your time machine back to 1937-38 and pick your engine before either P & W and Wright even finishing developing it at the home plant and tool up you factory to make this non extent engine and secure your supply of non existent fuel you might be able to make a somewhat decent fighter out of the F5-34 in 1939-40.

 

[Shortround6]

The P & W R-1830 had a long history and was first run in 1931 and first production engines showed up in 1932. However this was a an 800hp engine at 2400rpm and could maintain that power to 4500ft using a General Electric supplied (or designed?) single speed mechanical supercharger.
By the time the R-1830-13 engine showed up in 1938 for the P-36s the engine could give 1050hp for take-off at 2700rpm. However they were on the 3rd cylinder design along with a number of other improvements. They were using a larger diameter supercharger for one thing and much improved finning for cooling.
P & W started design of a two stage supercharger in 1935 with a single speed and both impellers on a single shaft. Performance was poor and P & W tried intermediary and two speed drives and it was not until end of 1938/ beginning of 1939 that a useable engine was built and further improvements were made in early 1939 which lead to the R-1830-19 with an entirely P & W designed supercharger and that lead to the R-1830-76 which lead to the R-1830-86 which was used in most of the early F4F-3s/4s.
The early experimental two stage engines were heavier (over 1600lbs) than the later versions, in part due to P & W using more magnesium castings instead of aluminum.

P & W changed a lot of other things like changing the bearing materials.

But like a lot of other radial engines they didn't have a lot of stretch in them as built. The stretch came from near constant improvements and modifications. You could often bolt a new engine to an old motor mount (kind of) but rebuilding an old engine to a new standard was a lot harder, if it was allowed at all. Later R-1830s in B-24s got cylinder barrels with deeper fins. engines with harmonic balancer style crankshafts showed up and other behind the scenes improvements, not always reflected in higher power outputs.

Unlike Allisons or Merlins the R-1820 and R-1830s were never given WEP ratings retro-actively. later versions were allowed to make more power but there were always modifications to the engine that justified the higher ratings. Even the 1300-1350hp R-1820s used in the FM-2 were different. The 1350hp version had a different crankshaft than the 1300hp version although I believe (?) the 1300hp version could be rebuilt using the new crankshaft.

 

[yulzari]

An improved Gloster would either be a Hurricane or a Spitfire. To draw upon the available alternative engines i.e. Mercury or Perseus, you would need to glue another airframe onto the back of it. A general model in weight and dimensions might be the Vickers Venom but to Mercury/Perseus scale. For the role envisaged an actual larger Venom would be a better choice than a shrunken Gloster. The Gloster is too much airframe chasing too little power. As it stands IOTL it offers nothing more against the Hurricane and Spitfire other than using another engine and no reason to expect that engine to make usefully more power with development.

Looking back with 21st century hindsight, having Gloster make Hurricanes and using the Battle's Merlins would balance with the Mercury and Perseus going into Fairiy's suggested twin engined Battle. The production bottleneck would then be over enough Mercuries and/or Perseus to share with the Blenheim production.

Really I cannot see what the Gloster, even if improved, brings to the table; nor how it could be improved other than with a different airframe.

 

[Shortround6]

Gloster was already busy and like many British companies was stretching itself a bit thin with the result that things took longer than they expected.

Expected engines were The Sabre or Vulture. Used nosewheel undercarriage.
Not to be left behind Bristol was replacing the type 153 with this

At least the pilot would have been warm at high altitude

Having a flying prototype does NOT mean you have production drawings (drawings of the parts at various stages of manufacture) or drawings of the tooling (jigs/fixtures) needed to make production aircraft.

 

[tomo pauk]

Looking back with 21st century hindsight, having Gloster make Hurricanes and using the Battle's Merlins would balance with the Mercury and Perseus going into Fairiy's suggested twin engined Battle. The production bottleneck would then be over enough Mercuries and/or Perseus to share with the Blenheim production.

Really I cannot see what the Gloster, even if improved, brings to the table; nor how it could be improved other than with a different airframe.

Gloster's fighter needs the Merlin in order to be useful by 1940.
One can also ask - what does the twin engined Battle brings to the table?

 

[Admiral Beez]

Gloster's fighter needs the Merlin in order to be useful by 1940.

We're replacing rather than improving the F5/34 in that case. Is the P-40 just a P-36 with an inline engine stuck on? I'm not so sure.

Really I cannot see what the Gloster, even if improved, brings to the table; nor how it could be improved other than with a different airframe.

Considering that Gloster's owners are already making the Hurricane, the only thing the Gloster brings to the table is the potential for the RAF's first single-seat, monoplane radial-powered fighter to enter production since the Bristol M.1, replica shown below. It's noteworthy that the British didn't produce any new ones until the post-war, Centaurus-powered Firebrand, Fury and Tempest II. Until then, the best single engined, single-seat monoplane British radial-powered fighter was the Fokker D.XXI.

Interestingly, Hawker would not produce an all metal single-seat fighter until years after Folland's F5/34 design, in the Hawker Typhoon. It's too bad that Bristol let the nation down with its engines. Interestingly, Japan went the other way with the Ki-61 where it swapped in a radial to create the superlative Ki-100.

 

[Shortround6]

Is the P-40 just a P-36 with an inline engine stuck on? I'm not so sure.

Darn close.

XP-40 was the 10th P-36A on the production line.

Of course the P-36A needed a bit of sorting out even without the V-12 engine stuck in the nose.
In 1938 and early 1939 the P-36 deliveries were slow. Areas of the wing around the landing gear were buckling and needed reinforcement and that was at a normal gross weight of 5,650lbs and a max of 6010lbs. Fuselage skins were also wrinkling. There were groundings to apply fixes or limits were placed on maneuvers and airspeeds.
The XP-40 was flying in the Jan 1939 fighter trials.
The P-36C was ordered Jan 26th 1939 with the extra gun in each wing.
The XP-36D was ordered/modified Sept 1939 with two .50 cal guns in the fuselage (200rpg) and two .30 cal guns in each wing (500rpg) which added 400lbs.
The XP-36E (date???) was a P-36A that had modified wings with three or four .30 cal guns in each wing panel with 500rpg but the single .50 cal in the fuselage was not operational.
The XP-36F (date???) was a P-36A with a modified wing to mount a 23mm Madison cannon in a pod under each wing with 100rpg. By April of 1940 it was used to test a pair of 20mm Hispano guns.

What is of interest here, although it may be a coincidence, is that the P-40D was approved by the Army in June of 1940 although not officially ordered until Sept. It took until May 1941 for the first P-40D to show up (and the 2nd one became the first XP-40F) and the P-40Ds had the "provision" for a 20mm Hispano to be mounted underneath each wing. This went away with the P-40E with 3 guns in each wing instead of the two guns in each panel of the P-40D.


What we do know is that the P-36 and P-40 used identical wing planforms and airfoils even if the P-40 got a bit different wing structure as the P-40s got heavier.
It appears that the horizontal tail and vertical stabilizer stayed pretty much the same until the long fuselage P-40s showed up. and even then the horizontal stabilizer and elevators stayed in the same location and stayed the same size. The Fin and rudder were moved back.
Landing gear stayed pretty much the same (change in the doors aside) although it got beefed up a bit.

The P-36 to P-40 had fewer changes than some other fighters went through. Like the 109E to 109F.

Interestingly, Japan went the other way with the Ki-61 where it swapped in a radial to create the superlative Ki-100.

That needs a bit of interpretation.
The Ki-61 had two basic engines.
The Ha-40 of around 1080-1100hp at 3500-3900 meters used in the Ki-61 I variations .
The Ha-140 of 1500hp T-O and 1250hp at 5700 meters used in the Ki-61 II versions.
The Ha-140 was very unreliable and gave a lot of problems. Despite this the engine and the Ki-61 II was ordered into production in Sept 1944 but the US Air Force destroyed the Akashi engine plant on Jan 19th 1945. There were hundreds of Ki-61 airframes sitting without engines and no hope of getting any of the V-12s for months even if the plant could be repaired. The fitting of the Radial engine was a masterpiece of improvisation, not a planned improvement over the Ki-61 I with the Ha-40 engine.

The radial offered 1500hp T-O and 1250hp at 5900 meters. When the they worked the Ha-140 engine offered about 19mph (?) more speed at 6,000 meters.

For the P-36 and Early P-40s the records are on WWII Aircraft Performance

for the power needed to fly at different attitudes and speeds. The P-40 was much faster using the same power due to lower drag. Perhaps it was also due to using exhaust thrust. But the differences are in the tables. By 1943 P & W had sorted out the radial cowling and the exhaust system and while running light (over 1000lbs below normal gross weight) had the 4th fastest P-40 ever flown (only the P-40Qs were faster) but 1943 was too late to change production.

 

[Shortround6]

One can also ask - what does the twin engined Battle brings to the table?

Keeps money flowing into Fairey's pockets?


I usually don't like the idea of cutting off the Battle production and trying to substitute Hurricanes instead. Gloster did build a lot of the Hurricanes as it was. So how fast can you tool up extra production lines ? But the time you get to the fall of 1940 and into 1941 you had more Hurricanes than you knew what to do with. That is with hindsight but still. By the Spring of 1941 with the 10F showing up in increasing numbers the Hurricane was a liability in Europe. Having extra production just means you have to change it to something else.

For all practical purposes the the Mercury and the Perseus were interchangeable. 40-50hp out of 900hp at a certain altitude was not going to change the performance of an aircraft much.
Putting two Merseus engines on a Battle airframe just gives you a crappy Blenheim. It doesn't actually solve anything for the for the RAF (BC, CC, FC) as with the big radials the drag is going to suck up most of the extra power.
Fix the Blenheims before you make ersatz Blenheims.

 

[yulzari]

Gloster's fighter needs the Merlin in order to be useful by 1940.
One can also ask - what does the twin engined Battle brings to the table?

What the twin engined Battle brings is a means to release Merlins into the fighter production. Also gives @1,700bhp to power the Battle which can do no harm and can carry the same, even more externally, bomb load as a Blenheim and with at least the same performance other than range. But the key is getting Merlins into fighters instead of Battles.

Another question that needs answering is, if Gloster makes some sort of F5/34, what else will they not be making instead?

 

[tomo pauk]

What the twin engined Battle brings is a means to release Merlins into the fighter production. Also gives @1,700bhp to power the Battle which can do no harm and can carry the same, even more externally, bomb load as a Blenheim and with at least the same performance other than range. But the key is getting Merlins into fighters instead of Battles.

If were making another, say, 1000 of 2-engined Battles instead of 1000 of historical Battles, that means someone has to find another 1000 of, at least, 2-pitch props. Quite a task, since we're already lacking hundreds of of 2-pitch props required for the fighters of the Fighter command (regardless of whether those are Hurricanes or Spitfires or the best F5/34s we can whip up). Bristol also needs to make another 2000 of Mercury engines.

IMO - the lower the investment into the whole Battle idea (be it 1- or 2-engined), the better for the RAF.

Another question that needs answering is, if Gloster makes some sort of F5/34, what else will they not be making instead?

Last batches of Gladiators; last 16 were delivered as late as 1940.
Henleys, Hurricanes.