Sten SMG aircraft: productionized aircraft part 2, the what if

[GrauGeist]

I noticed upthread that some comments pointed toward plywood as a weight saving factor.

Plywood (laminated birch/poplar veneer) is not lightweight at all. It is a strategic material alternative, but certainly not weight saving.

 

[z42]

Going back to the earlier premise of ease of production instead of just light weight and one of the Finnish
examples
View attachment 739318
Same engine as the Bf109G. They address the landing gear problem. They also added about 14% in wing area.

Unfortunately details are lacking or inconstant (or not identified correctly). Apparently the prototype was never given guns? so weight are either off or performance is off or ???

Not sure about the guns. The Pyörremyrsky wasn't ready for its first flight until after the war, and at that point it seems work continued on the prototype more as a make-work program rather than as something the air force was seriously considering, since the writing was clearly on the wall for piston powered fighters and the air force had sufficient numbers of Bf 109's in service until they were replaced by jets. So it's entirely possible they never bothered installing guns (or for that matter, equivalent ballast) for the test flights.

Another, earlier, Finnish fighter is more instructive. VL Myrsky
View attachment 739319

Now the project started in May 1939 (?) with the initial requirements, first flight took place Dec 23rd 1941 and first units got production aircraft in 1944. Which is actually not too bad.
It also allowed some later innovations to be used. Like cowling and exhaust thrust ideas that were not in existence in 1940-41. This did allow for better performance than was allowed by 1939-41 production fighters using similar engines. Yes it used wooden construction as noted earlier and it had problems with bad glue.
More subtle problems were the 300 liter fuel capacity and the rather restricted ammo capacity one source says 220rpg for the inner guns and 260rpg for the outer guns. This may have suited conditions in Finland but perhaps not in some other areas?

Also illustrative is that back then airplane technology developed so fast that at the point the VL Myrsky entered service it was already obsolete as a fighter, outclassed by the Bf 109G's the Finnish Air Force were using. So all the Myrskys were allocated to reconnaissance squadrons.

 

[tomo pauk]

Japanese options:
- Ki-27 with the 1st of Sakaes (better power all-around, less drag) + a better prop; give it another pair of MGs for the obvious reasons; retractable U/C might come in handy
- A5M with Zuisei, enclosed cockpit as in some prototypes, add a bit of firepower, again the retractable U/C will be nice to have
Both of them will require a bit more of fuel.

Shortly after that:
- Ki-60 with Sakae/2-speed Zuisei/Ha-41/-109/Kinsei
- Ki-44 with Kinsei or 2-speed Sakae
(both are small fighters, so it should be easier to produce them than their bigger stablemates like the Ki-61 or Ki-43; engines suggested are in series production, not some new fancy models)

 

[Shortround6]

Japanese options:
- Ki-27 with the 1st of Sakaes (better power all-around, less drag) + a better prop; give it another pair of MGs for the obvious reasons; retractable U/C might come in handy
- A5M with Zuisei, enclosed cockpit as in some prototypes, add a bit of firepower, again the retractable U/C will be nice to have
Both of them will require a bit more of fuel.

I am not sure what you save? or gain?
Ki-27 was about 1000lbs lighter empty than a Ki-43. In part due to the 435kg engine (?) the ground adjustable 2 blade propeller, The fixed landing gear and the two MG (12.7kg each)with 500rpg. Ki-27 held 330 liters of internal fuel.
The Early Sakae engine was about 530kg, The later ones with 2 speed supercharger went about 590-600kg?
Unknown weight change for a two pitch prop.? Ki-43 II got the constant speed prop.
Retractable landing gear?
Even two more Type 89 machine guns are 50kg not including mounts, ammo boxes, etc.
The Ki-43 gained about 15% in wing area.
The Ki-43 II got the 2 speed supercharger and constant speed prop and gained about 300lbs in empty weight over the Ki-43 I.
The Japanese 12.7mm aircraft gun was 43kg or about 2.5 kg lighter than two of the 7.7mm guns.

I am not sure what you save in materials/ labor by building the K-27 "Super" vs the Ki-43 I with the same engine, prop, guns, especially if you stick retracting landing gear on the K-27 "super". cost of the extra 30 sq ft of wing area?

Pretty much the same for the A5M which used the same engine as the Ki-27.
The early Zuisie went around 540kg. Not sure if the A5M had a controllable pitch prop or not. But you want one for the Zuisie engine. Same problem for the extra machine guns, that assumes the Japanese have the production capacity for the extra machine guns early in the war.

You want an A6M "light"? and you are short of Sakae engines? stick Zuisies in the A6M airframes. You already have the wing gun positions and most of the airframe and landing gear parts should interchange. (cost savings right there).

Shortly after that:
- Ki-60 with Sakae/2-speed Zuisei/Ha-41/-109/Kinsei
- Ki-44 with Kinsei or 2-speed Sakae
(both are small fighters, so it should be easier to produce them than their bigger stablemates like the Ki-61 or Ki-43; engines suggested are in series production, not some new fancy models)

Don't confuse smaller with light weight or easy to build.
The Ki-60 was pretty much of a dog in many respects. The Ki-61 had much lower drag and better flying characteristics. The entire fuselage was reduced in height for one thing.
There were only 3 Ki-60s so there was not tooling to "save".

Ki-44 exists, in part, due the Kinsei and Sakae not delivering the desired power at the needed times. In 1940-41 and part of 1942 the smaller Japanese engines were nowhere near 1250hp. An under 1000hp Ki-44 would have offered nothing over the Ki-43, By the time you get 2 speed Sakae or Kinsei engines the Nakajima engine is giving 1450hp or is very near.

 

[z42]

I noticed upthread that some comments pointed toward plywood as a weight saving factor.

Plywood (laminated birch/poplar veneer) is not lightweight at all. It is a strategic material alternative, but certainly not weight saving.

Not sure if this comment is aimed at my previous comment immediately above, anyway my comparison above was for a steel framework covered with fabric vs. a steel framework covered with a stressed plywood skin. High quality (aero) plywood has a specific modulus in the same ballpark as steel, thus I speculate that the plywood version, by allowing a lighter steel framework as the skin takes up some of the load, vs. the fabric version where the fabric is complete deadweight from a structural perspective, could be lighter overall as well as not suffering from the skin distorting out of shape in a high speed dive.

A stressed skin duralumin construction would likely be even lighter, yes, but e.g. the Mosquito being an existence proof that it was possible to make superb combat planes out of wood composite back then.

 

[tomo pauk]

I am not sure what you save? or gain?
Ki-27 was about 1000lbs lighter empty than a Ki-43. In part due to the 435kg engine (?) the ground adjustable 2 blade propeller, The fixed landing gear and the two MG (12.7kg each)with 500rpg. Ki-27 held 330 liters of internal fuel.
The Early Sakae engine was about 530kg, The later ones with 2 speed supercharger went about 590-600kg?
Unknown weight change for a two pitch prop.? Ki-43 II got the constant speed prop.
Retractable landing gear?
Even two more Type 89 machine guns are 50kg not including mounts, ammo boxes, etc.
The Ki-43 gained about 15% in wing area.
The Ki-43 II got the 2 speed supercharger and constant speed prop and gained about 300lbs in empty weight over the Ki-43 I.
The Japanese 12.7mm aircraft gun was 43kg or about 2.5 kg lighter than two of the 7.7mm guns.

Against the Ki-43, one thing what I gain is what cannot be bought - timing. As well as far lighter weight, even once better powerplant is installed.
Ki-43 have had not a bigger wing, but also with a thicker profile, at root 18% vs. 16% on the Ki-27. So our valiant 'super Ki-27' should be in the ballpark with the Ki-43-I speed-wise (and faster if the retractable U/C is installed), but also climbs better.

We can recall that the thread is about the Sten gun equivalent of an aircraft, not the FG-42 equivalent - IOW not 'let's make the best, top notch machine', but 'let's make a machine that can be had en-masse and still do the job'.

I am not sure what you save in materials/ labor by building the K-27 "Super" vs the Ki-43 I with the same engine, prop, guns, especially if you stick retracting landing gear on the K-27 "super". cost of the extra 30 sq ft of wing area?

Time needed to retool the factory for another airframe is notable save.

Pretty much the same for the A5M which used the same engine as the Ki-27.
The early Zuisie went around 540kg. Not sure if the A5M had a controllable pitch prop or not. But you want one for the Zuisie engine. Same problem for the extra machine guns, that assumes the Japanese have the production capacity for the extra machine guns early in the war.

You want an A6M "light"? and you are short of Sakae engines? stick Zuisies in the A6M airframes. You already have the wing gun positions and most of the airframe and landing gear parts should interchange. (cost savings right there).

Admittedly, and since Zero was earlier in production than the Ki-43, advantages of the 'super A5M' idea are lesser than what 'super Ki-27' can offer timing-wise.

Don't confuse smaller with light weight or easy to build.
The Ki-60 was pretty much of a dog in many respects. The Ki-61 had much lower drag and better flying characteristics. The entire fuselage was reduced in height for one thing.
There were only 3 Ki-60s so there was not tooling to "save".

A part of Ki-61 improvement was the cooling system, that obviously does not play the part here with the radial in the nose. Radial of the day is anyway taller than a V12 (requiring for the Ki-100 to gain a bit of 'beard' in order to streamline the installation), so again the taller fuselage is not a hindrance.
Smaller airframe - here mostly the smaller wing will require less ribs and less rivets, meaning the potential to lower than manhours count.
Better flying characteristics of the Ki-61 vs the -60 were due to a bigger wing so there was the lighter wing loading; here I've suggested lowering the weight, so there is improvement of wing loading.

While there is not much of tooling to 'save' at Kawasaki, there is a lot of time and trouble to save by not going on with the Ha-40 engine.

Ki-44 exists, in part, due the Kinsei and Sakae not delivering the desired power at the needed times. In 1940-41 and part of 1942 the smaller Japanese engines were nowhere near 1250hp. An under 1000hp Ki-44 would have offered nothing over the Ki-43, By the time you get 2 speed Sakae or Kinsei engines the Nakajima engine is giving 1450hp or is very near.

Ki-44 offers, vs. Ki-43, the smaller wing-related drag for better speed, better rate of roll, much better dive capabilities, better weapon load. It also requires one spar for the wing to be made vs. three for the Ki-43, as well as less ribs to be made, plus less riveting - all contributing to the potential for faster production. It also offers that Nakajima makes just one type of Army fighters (albeit with different engines) in 1943 and better part of 1944 in one factory, benefiting wrt. economies of scale.

I don't recall me suggesting that historical Ki-44 should be cancelled.

 

[tomo pauk]

Potez 230 Along with 3/4 other "light fighters".
However the French were a little too obsessed with speed and not so much with actual usefulness. The little Potez was supposed to do 342-350mph. depending on source although it was never fitted with guns (same as a D. 520) so actual in service speed is a little questionable. The other problem was it's 118sq ft wing. This might be a misprint but it's 3 stable mates all used small wings.
Bloch 700. 134sq ft G-R 14 M engine
C. 714 135sq ft Renault V-12
Roussel R. 30 110 sq ft G-R 14 M

All had wing loading on the high end for their time and French Airfields were often not the Best (understatement).
The C.714 had two derivatives, one with the Italian I-F Delta engine and the other with an experimental Renault V-16 (broke it's crankshaft on the first flight, go figure).

Squeezing another airframe into that mess and expecting a different result?

French certainly need to revamp their fighter program(s) a few years earlier in order for these to bear fruit. Seems to me that they endured a lot of trial and error a few years after the British did the same (where the monoplanes' prototype fighters were with severe shortcomings, but a few years later that gave them - and us all - Hurricanes and Spitfires). It helped a lot to the British that RR was delivering Merlins that gave far better power than what French had, thus a hiccup with a high-drag fighter was not such a problem at the end.

For the British?
Used airframes and engines or new construction (and/or rebuilt engines?)
Hawker Furies had a number of models. including

Which hit 242mph. Landing gear of similar type to the Gladiator.
Several versions had a pair of guns in the cowl top and an gun in each side of the fuselage (Vickers guns, British didn't put them in the wings) although one customer put a gun under each wing.
But you are expecting a lot from a 700hp engine even if you cut the wing a bit compared to the 1030hp Hurricane.

The Ki-27 only had to deal with two guns and it used a 199.8 sq ft wing. 330 liters of fuel.

My idea is that the 'real' Fury monoplane is produced instead of the Gladiator. 745 HP at 14500 ft, as on the 'Yugoslav Furies' as depicted above.

Historically, as I'm sure we all know, the monoplane version of the Fury, with a new engine and retractable U/C, became the Hurricane, which for all its faults was still a phenomenally successful aircraft. How much cheaper will the above suggestion really be compared to the Hurricane, and is the savings in cost really worth the cost in performance compared to the Hurricane? Further, if Hawker would have concentrated on making the above product, that would probably have delayed the Hurricane project, likely putting Britain into a much more difficult position in the early war years.

FWIW, I consider the Hurricane a separate fighter type, not a version of the Fury.
The monoplane Fury, as noted above, should be produced instead of the Gladiator, not instead of Hurricane.

Just put the second-tier engines into transports, patrol aircraft and some bombers, and use the best engines you have for fighters. Yes, not the topic of this thread, but that would be my recommendation. If one wants cheaper, what could e.g. Hawker have done to make the Hurricane cheaper to produce and operate, without sacrificing much capability of the aircraft?

Fixed U/C? For service use certainly better thing than having a biplane.
I'd also try to came out with a smaller wing and the 'beard' radiator.

 

[Shortround6]

French certainly need to revamp their fighter program(s) a few years earlier in order for these to bear fruit. Seems to me that they endured a lot of trial and error a few years after the British did the same (where the monoplanes' prototype fighters were with severe shortcomings, but a few years later that gave them - and us all - Hurricanes and Spitfires). It helped a lot to the British that RR was delivering Merlins that gave far better power than what French had, thus a hiccup with a high-drag fighter was not such a problem at the end.

Unfortunately the French solution was not to increase the power of the basic engines (or they tried too slowly) but to reduce the drag of the fighters to such an extent that they could use even lower powered engines. The French had a real obsession with numbers and chose to sometimes ignore actual combat effectiveness. See armor and artillery.
British were at least smart enough to realize that the aircraft they were specifying had to operate out of existing airfields and not just the most spacious, best maintained airfields in the country. The French had been overly impressed by their own cleverness with a few 1934-36 racing airplanes.

replica.

With a special racing engine they got them to go over 300mph in 1936. But racing planes are not fighter planes. Enlarging the wing enough to get a few guns in (and have some hope of actually landing the plane) and sticking in an even bigger engine was not really a short cut.

My idea is that the 'real' Fury monoplane is produced instead of the Gladiator. 745 HP at 14500 ft, as on the 'Yugoslav Furies' as depicted above.

The monoplane Fury, as noted above, should be produced instead of the Gladiator, not instead of Hurricane.

Problem here is production and design staff. Hawker was designing and setting up for production of the Hurricane, once RR figured out the PV 12-Merlin.
Gloster, while owned by Hawker, had design staff and manufacturing capabilities to build an improved Gauntlet. The programs overlapped, they were not in parallel even if they were not in sequence. Hurricane barely made it as it was. Delaying the Hurricane by 6 months while they fooled around with a "Fury" monoplane?
And again, the Gladiator got landing flaps to meet the requirements for landing distance. Would the Mono-plane Fury have made it? It's wing was about 2/3 the size of the Supermarine 224. which did not meet the landing requirement.

 

[tomo pauk]

Unfortunately the French solution was not to increase the power of the basic engines (or they tried too slowly) but to reduce the drag of the fighters to such an extent that they could use even lower powered engines. The French had a real obsession with numbers and chose to sometimes ignore actual combat effectiveness. See armor and artillery.

The French that were trying to reduce drag were not the same French that were trying to increase engine power. Same as the British trying to reduce drag were not the same British trying to increase the engine power.
If the French have had obsession with numbers of military aircraft, they did a great job of hiding it - Germans out-produced them in any year past 1936?

 

[Shortround6]

We can recall that the thread is about the Sten gun equivalent of an aircraft, not the FG-42 equivalent - IOW not 'let's make the best, top notch machine', but 'let's make a machine that can be had en-masse and still do the job'.

Time needed to retool the factory for another airframe is notable save.

If you are modifying an 6,000lb airplane you have a lot more room than when you are modifying a t 3,000lb airplane.
Ki-27 was actually just under 2500lbs empty. If you try to turn it into a Ki-43 "light" the weight climbs quickly, which means you have to beef up the structure, some of the common airframe disappears.
The Japanese could have had the Ki-43 a number of months earlier if they had been willing to forgo a few things, Like the combat flaps and the insistence that an over 4,000lb plane maneuver like a 3400lb plane. The change in range was also a mid project change, 564 liters of internal fuel (plus 400 liters of external) gave the Ki-43 much the same range as a Zero.
It also means that you need a larger, heavier plane than the Ki-27.
Ki-27 tooling was sent to a different factory starting in the fall of 1940. Hundreds if not well over 1000 Ki-27s were built at the new factory.

Radial of the day is anyway taller than a V12 (requiring for the Ki-100 to gain a bit of 'beard' in order to streamline the installation), so again the taller fuselage is not a hindrance.

That is one fat airplane
You are not getting a Ki-100 earlier.

Better flying characteristics of the Ki-61 vs the -60 were due to a bigger wing so there was the lighter wing loading; here I've suggested lowering the weight, so there is improvement of wing loading.

While there is not much of tooling to 'save' at Kawasaki, there is a lot of time and trouble to save by not going on with the Ha-40 engine.

Trouble is that when you go to the radials of the time the performance goes in the toilet.
The Ha-40 engine promised (delivery was questionable) both more power, better streamlining and better exhaust thrust than the radials.
The Ki-100 was about 8mph slower at the Ki-61s best height despite having both more power (around 150hp?) and better exhaust thrust than any 1942/43 Japanese aircraft had.
The Ki-44 had about 200-220hp more than the Ki-61 had at altitude and was about 16mph faster (Ki-44 did not make good use of the exhaust thrust) despite it's size.
Anything smaller in 1942/43 than the engine in the Ki-44 gives you less performance no matter what you do to the wing.

Airframe cost varied but it might be only 30-40% of the cost of a fighter aircraft. It is the cheapest cost on a per pound basis.

 

[tomo pauk]

That is one fat airplane

Hopefully the radial in the nose can help us get rid of the bathtub (radiator) under the fuselage, thus making the aircraft more slender

You are not getting a Ki-100 earlier.

Haven't claimed I do.

Trouble is that when you go to the radials of the time the performance goes in the toilet.
The Ha-40 engine promised (delivery was questionable) both more power, better streamlining and better exhaust thrust than the radials.
The Ki-100 was about 8mph slower at the Ki-61s best height despite having both more power (around 150hp?) and better exhaust thrust than any 1942/43 Japanese aircraft had.
The Ki-44 had about 200-220hp more than the Ki-61 had at altitude and was about 16mph faster (Ki-44 did not make good use of the exhaust thrust) despite it's size.

Performance of the IJA fighters was already in the toilet (bar what Ki-44 did) - we have a whole thread where this is discussed Ha-40 was best in being too late for the power it was offering. The radial Ki-60 would've been a smaller aircraft than the Ki-100 (meaning the drag can be lower), but what it would do the best will be the timing.
Nothing prevents the Japanese on installing better exhaust stacks on the radial Ki-60 once they have that figured out (second half of 1943?), along with better engines as they became available.

Anything smaller in 1942/43 than the engine in the Ki-44 gives you less performance no matter what you do to the wing.

It gives me better performance than the Ki-43.

 

[Shortround6]

The French that were trying to reduce drag were not the same French that were trying to increase engine power. Same as the British trying to reduce drag were not the same British trying to increase the engine power.
If the French have had obsession with numbers of military aircraft, they did a great job of hiding it - Germans out-produced them in any year past 1936?

May depend on how and what you are counting.

French numbers are all over the place. Since they had a crap load of planes that date back to before 1936 things get skewed rather quickly.
Wiki. "At the start of the conflict, significant numbers of D.510s were still in operation with three Groupes de Chasse (Fighter Groups), two Escadrilles Régionale de Chasse (Regional Fighter Squadrons in North Africa), and two Escadrilles de Aéronautique Navale (Naval Aviation Squadrons)."
Now these were pretty much useless for 1st line combat
You can find this statistic.
"In May 1940, the French had 4,360 combat aircraft vs. 3,270 for the Germans. However, the French had only a fourth of these aircraft in operational formations on the Western Front."
The Germans were NOT counting or flying a crap load of antiques (Dornier 23 bombers).
French also often counted aircraft sitting on the manufactures factory ramps, even though they were not ready to fly, government supplied radios, gunsights, some instruments and even propellers not being installed on "completed" aircraft. Hey, the numbers looked good

And the French had too many aircraft that just would not do the job.

Over 700 of these were delivered before France fell, there were almost 1400 of the family built. But they were cheap
The Famous G-R 14M engine of about 700hp. Airframe was cheap, supposedly cheaper than an Ms 406?
Smaller bomb load than Blenheim, slower, less range than a MK IV, better for strafing though!

Large numbers of squadrons without adequate ground crew and supplies means less actual missions per day.
It is a balance and large numbers of inadequate planes and inadequate support/supply is not a winning combination.

If manpower and/or supply (fuel) are short then having effective aircraft is the only hope, more planes you cannot support is a waste of money/resources.

 

[tomo pauk]

May depend on how and what you are counting.

French numbers are all over the place. Since they had a crap load of planes that date back to before 1936 things get skewed rather quickly.
Wiki. "At the start of the conflict, significant numbers of D.510s were still in operation with three Groupes de Chasse (Fighter Groups), two Escadrilles Régionale de Chasse (Regional Fighter Squadrons in North Africa), and two Escadrilles de Aéronautique Navale (Naval Aviation Squadrons)."
Now these were pretty much useless for 1st line combat
You can find this statistic.
"In May 1940, the French had 4,360 combat aircraft vs. 3,270 for the Germans. However, the French had only a fourth of these aircraft in operational formations on the Western Front."
The Germans were NOT counting or flying a crap load of antiques (Dornier 23 bombers).
French also often counted aircraft sitting on the manufactures factory ramps, even though they were not ready to fly, government supplied radios, gunsights, some instruments and even propellers not being installed on "completed" aircraft. Hey, the numbers looked good

You know what M. Twain said about statistics

Over 700 of these were delivered before France fell, there were almost 1400 of the family built. But they were cheap
The Famous G-R 14M engine of about 700hp. Airframe was cheap, supposedly cheaper than an Ms 406?
Smaller bomb load than Blenheim, slower, less range than a MK IV, better for strafing though!

Part of being Sten-like is the ability to do the job
MS.406 - crucial if the French are to defend themselves, since RAF will not send it's best and in numbers needed, and there is no Eastern front for the Germans to divide their forces - was neither producible, nor was able.

Large numbers of squadrons without adequate ground crew and supplies means less actual missions per day.
It is a balance and large numbers of inadequate planes and inadequate support/supply is not a winning combination.

If manpower and/or supply (fuel) are short then having effective aircraft is the only hope, more planes you cannot support is a waste of money/resources.

Granted, there is much more to the airforce than what new, shiny aircraft can be produced.

 

[Shortround6]

Granted, there is much more to the airforce than what new, shiny aircraft can be produced.

A fighter squadron can have over 100 ground crew, which have to housed (even in tents) and fed.
Small cheap fighters with a lower number of guns only reduces the number of ground crew a small amount.
Powerful engines suck fuel when running hard. At cruising speeds the fuel consumption is a lot closer. Fuel consumption per sortie may not be as different as percentage of the peak power.
And you need enough guns to kill/damage the enemy aircraft. If some (not all) He 111s could make it home with 200 .303 hits (scrapped after landing?) from eight gun fighters how many 4 or 6 gun fighters do you need? Or do you need better pilots? With more time in trainers and gunnery courses?

For the US and Japanese who operated very far from the factories using less than the best available aircraft could put increasing strains on supply chains.

Granted we have the benefit of hindsight.
The US also had the benefit of by far the most mechanized support structure of any force in WW II, more than one General listed the Bulldozer as one of the 5 most important weapons of the war. Field length was of less importance to the US as they could make the airfield larger with ease, assuming there was land available (and sometimes even if there wasn't).

 

[tomo pauk]

A fighter squadron can have over 100 ground crew, which have to housed (even in tents) and fed.
Small cheap fighters with a lower number of guns only reduces the number of ground crew a small amount.
Powerful engines suck fuel when running hard. At cruising speeds the fuel consumption is a lot closer. Fuel consumption per sortie may not be as different as percentage of the peak power.
And you need enough guns to kill/damage the enemy aircraft. If some (not all) He 111s could make it home with 200 .303 hits (scrapped after landing?) from eight gun fighters how many 4 or 6 gun fighters do you need? Or do you need better pilots? With more time in trainers and gunnery courses?

At least two things to note:
- my suggestions rarely, if ever included the reduction of armament
- not everything is about RAF

Granted we have the benefit of hindsight.
The US also had the benefit of by far the most mechanized support structure of any force in WW II, more than one General listed the Bulldozer as one of the 5 most important weapons of the war. Field length was of less importance to the US as they could make the airfield larger with ease, assuming there was land available (and sometimes even if there wasn't).

Most of countries with airforces worth talking about have had many years to improve and enlarge their airfields.

 

[Bretoal2]

With a special racing engine they got them to go over 300mph in 1936. But racing planes are not fighter planes

Yes. The French "chasseur jockey" program was an entire failure. A high-speed racing plane becomes a workhorse when loaded with weapons, ammunition and extra fuel. Don't forget all the military equipment: navigation instruments, radio, oxygen, etc, and I don't speak about armour protection....

Thanks to the talent of Marcel Riffard, with less than 500 hp an aircraft like the Caudron C 714 could create an illusion in the maximum speed domain, which reached that of the Morane 406. Unfortunately, the climbing speed was very poor (4,000 m. in 7'02 ", 7,000 m. in 15'00").

In fact, decent performances with this model required 50 to 75% more power, as demonstrated by the Caudron C 760 (730 hp Isotta-Fraschini engine) or C 770 (800 hp Renault engine). But this was the power of the Gnome-Rhône 14M which equipped the Bloch 700 and Roussel 30 fighters, both extremely promising. Roussel 30 metal construction must have been much more robust than the wooden structure of Caudron (The Bloch 700 had a wooden structure too).

And 700 hp is also the power of the Hispano-Suiza 12X of the Potez 230...

 

[Shortround6]

At least two things to note:
- my suggestions rarely, if ever included the reduction of armament
- not everything is about RAF

The French C. 714, the only light fighter to be built in quantity by the French, used four 7.5mm machine guns.
The Italian SAI 207, 14 built, 13 of them with a pair of 12.7mm guns, standard for 1939-40 but they were built in in 1941-43.
The US Bell XP-77 had two .50 cal guns and the less said about that one the better

Most of countries with airforces worth talking about have had many years to improve and enlarge their airfields.

Well, we are back to the French, who did not improve or enlarge their airfields, mostly, between WW I and WW II.
Italy? Either home or in Africa?
Japan with construction battalions equipped with shovels?
One reason for float plane fighters.
Soviet Union for "most" airfields. Not PE-8 airfields.
I will leave out the RAF on your say so

 

[z42]

Airframe cost varied but it might be only 30-40% of the cost of a fighter aircraft. It is the cheapest cost on a per pound basis.

Also, probably the cost of the airframe scales sub-linearly as a function of the weight. Yes, the material costs are obviously linear, but a lot of the work steps will be the same for a bigger frame. And same for engines. A big V-12 is going to be more expensive than a smaller one due to more materials needed, and more material that needs to be machined away as part of the manufacturing process. But the manufacturing steps will be essentially the same. Thus, on a cost per hp basis, the bigger one should win. Of course, if you jump up to a H-24 configuration and decide to use something exotic like sleeve valves, sure costs are going to balloon.

So one might not win as much as one might think from going to a smaller plane, even discounting the support systems that have to be roughly the same, instruments, radios, guns, controls etc. etc. That doesn't of course mean that one shouldn't care about the size, a bigger airframe will need a bigger engine, which needs sturdier construction, more fuel etc. which again might warrant a bigger airframe, rinse and repeat.

But as a starting point for a fighter design, it's probably a good idea to start with the biggest most powerful engine that is available. And nations which didn't have such engines compared to their rivals, suffered.

 

[z42]

The monoplane Fury, as noted above, should be produced instead of the Gladiator, not instead of Hurricane.

I think it's unlikely Hawker would have the manpower to take on this project without impacting the timetable of the Hurricane. Now, if the Merlin would have been delayed by several years, this might have been a worthwhile project, but in OTL I don't see it making sense.

Fixed U/C? For service use certainly better thing than having a biplane.

How much the fixed U/C save on the cost of the entire plane vs. how much does it reduce performance? I suspect the tradeoff is not going to look favorable.

I'd also try to came out with a smaller wing and the 'beard' radiator.

Do you mean smaller as in smaller area or thinner? Smaller area I'm not so sure about, would have made it faster, sure, but also reduced turning performance and increased landing speed. I suspect the Hurricane wing area was a pretty decent compromise as it was.

As for a thinner wing, sure. But then again Camm got on the thin wing bandwagon in the transition from the Typhoon to the Tempest, it's perhaps a bit optimistic to postulate he could have done that already for the Hurricane?

And for the radiator, I don't know. The Hurricane one apparently wasn't that good, but it seems no really good low drag ones were successfully made of the chin/beard variant either.

 

[tomo pauk]

I think it's unlikely Hawker would have the manpower to take on this project without impacting the timetable of the Hurricane. Now, if the Merlin would have been delayed by several years, this might have been a worthwhile project, but in OTL I don't see it making sense.

We disagree.

How much the fixed U/C save on the cost of the entire plane vs. how much does it reduce performance? I suspect the tradeoff is not going to look favorable.

Not that much of the save of cost, more of save of time? Main advantage is in half of number of wings vs. biplane, though.
Wrt. the cost in speed, Finnish were gaining average of about 25 km/h (~15 mph) when they were experimenting with retractable U/C for their Fokker fighters.

Do you mean smaller as in smaller area or thinner? Smaller area I'm not so sure about, would have made it faster, sure, but also reduced turning performance and increased landing speed. I suspect the Hurricane wing area was a pretty decent compromise as it was.

Both thinner (since the thickest part is removed/not produced for the monoplane Fury) and in area.
At 170-180 sq ft, it will be plenty enough for something much lighter than the Hurricane.
I do find the thickness and area of Hurricane wing as being too big, however that was the 1st Hawker's monoplane and it needed to fit pretty restrictive airstrip limitations, so one should not be too harsh on them.

As for a thinner wing, sure. But then again Camm got on the thin wing bandwagon in the transition from the Typhoon to the Tempest, it's perhaps a bit optimistic to postulate he could have done that already for the Hurricane?

And for the radiator, I don't know. The Hurricane one apparently wasn't that good, but it seems no really good low drag ones were successfully made of the chin/beard variant either.

I also don't expect that it will be easy to retrofit the Hurricane with the thin wing.
Beard radiator was an improvement for the XP-40 and Typhoon, both aircraft starting with belly radiators. It at least reduces the frontal area of the Hurricane. The closely-coupled system should be easier to make and be lighter, as well as offering less of the target for enemy bullets.