Dewoitine D.520 VS Heinkel He 112, which one has more development potential

[stoxm73]

One lose to 109 on test field, the other lose to 109 on battle field

The question is which one has more potential to be developed into a machine like late spitfires?

 

[YavorD]

From my point of view the main advantage of the early Bf 109 in comparison with the Heinkel design was simplicity and economy of mass production. At the time both fighters were powered by Jumo 210, an engine in the same performance class as Rolls-Royce Kestrel and Hispano-Suiza X.

Dewoitine D.520 was not exactly outclassed by the Bf 109 E but Luftwaffe was stronger fighting force in comparison with the French Air Force, and the Royal Air Force units in France during the first half of 1940. Technically both Dewoitine D.520 and Bloch 152 had development potential and could benefit from an economy of mass production (and powerful engines) if France was not forced to capitulate in June of 1940.

I am not ready to say what could happen if Heinkel or Dewoitine design was developed beyond 1940 ...

 

[tomo pauk]

FWIW, neither of the two companies was eager to continue with the respective designs: Dewoitine went with the D.551, Heinkel went with the He 100.
But, to be on the affirmative side, the D.520 strikes me as a more modern design than the He 112, even the 112B, and with the greater potential for the future development.

 

[Shortround6]

Which He 112 (wing shrank considerably from the early prototypes to production B models) and which late Spitfires?
MK V or MK VIIIs or Griffon powered?

There is a lot of hidden stuff that is hard to figure out. Like actual airframe strength and what is needed to change it.
Difficulty in changing/enlarging the cooling systems.
Changing centers of gravity.

A major Spitfire advantage is that starts out with a wing about 32% bigger so it can handle increases in weight somewhat better without low speed handling going in the toilet.

You can stick a bigger wing on the D. 520 and stick a 20mm in each wing when the new, larger engine takes up the space for engine mounted gun but if you change enough stuff do you really have a D.520 anymore?

Might want to move the cockpit around 1 meter further forward so there is some chance of doing deflection shooting.

 

[Elan Vital]

Wouldn't the He 112 be able to use the DB601/605 engines? In that case I see it more as a sidegrade to Bf 109, though people with proper knowledge on the airframe may be able to comment on this.

The D520 was supposed to continue development up to the D524 prior to the Armistice, using the Hispano-Suiza 12Z engine, a wing structure able to carry 3 7.5mm MGs per wing or 1 20mm cannon and 2 MGs per wing (the nose armament is not very clear), and aerodynamic improvements based on recent wind tunnel testing (and structural mods to make up for the increased weight).

The post-Armistice SE 520Z was basically an attempt to reintroduce a pseudo-D524.

The D520 series were supposed to be superseded by the D550 series, but by all accounts there was a decent development potential for the 520.

Though real-life performance will never be known and will be dependent on how the French engineers develop the 12Z engine, the D520 at least had the potential to compete with the Bf 109F.
I don't think it would ever have been a world-leading airframe compared to say the Fw 190 or the P-51 (and perhaps not even the D550 series would have been), and the French couldn't really match the Spitfire's engine development with the HS 12Z*, but it would have been broadly competitive.

*As long as the 12Z uses the bore/stroke of the 12Y, it will probably never be as efficient as the likes of the Merlin. If the French engineers play their cards well, they could benefit from high octane fuel, excellent US tooling and good materials and eventually outperform the DB 601/605 with the 12Z.

 

[Shortround6]

Maybe some people know the airfoils or at least wing thickness of the planes in question?
Might help answer questions about possible speed improvements.
He 112 did use the dreaded (from production standpoint) elliptical wing
Both planes used standard flaps and not the Spitfire split flap.

Spitfire got harder to handle in the later models, but it doesn't seem to have gotten really bad with bigger engines (but larger vertical stabilizer and rudder helped)
109 peaked for handling in F model. G's got worse or harder and late Gs and Ks got worse.
Going to 6500-7500lbs clean weight for the HE 112 or D.520 might have introduced a lot of problems.
How much can you modify or how much do you want to modify instead of starting over.
Supermarine did a masterful job upgrading the Spit and not screwing up production tooling too much.
This was especially handy as the Hawker was running into all sorts of problems with supposedly superior Typhoon and Tempest and their engines. Sticking an Merlin or early Griffon into one of the Big Hawkers wasn't going to work well.

 

[Elan Vital]

Maybe some people know the airfoils or at least wing thickness of the planes in question?
Might help answer questions about possible speed improvements.
He 112 did use the dreaded (from production standpoint) elliptical wing
Both planes used standard flaps and not the Spitfire split flap.

Spitfire got harder to handle in the later models, but it doesn't seem to have gotten really bad with bigger engines (but larger vertical stabilizer and rudder helped)
109 peaked for handling in F model. G's got worse or harder and late Gs and Ks got worse.
Going to 6500-7500lbs clean weight for the HE 112 or D.520 might have introduced a lot of problems.
How much can you modify or how much do you want to modify instead of starting over.
Supermarine did a masterful job upgrading the Spit and not screwing up production tooling too much.
This was especially handy as the Hawker was running into all sorts of problems with supposedly superior Typhoon and Tempest and their engines. Sticking an Merlin or early Griffon into one of the Big Hawkers wasn't going to work well.

D520 wing: wingspan 10.2m, 16 m² surface, 20% thickness, 167 kg/m² wing loading

It was envisioned to create a new wing with larger Mercier-type flaps to reduce landing speed (by 8kph) or maintain the landing speed at a greater weight

For day fighter missions the D520 weighed 2677 kg while the D524 protototype (520 with the 12Z engine but without the improvements that were being tested in mid-1940 in wind tunnels) was measured at 2802 kg (the project had been calculated at 2800 kg).

The D550 series were essentially a tradeoff+upgrade with reduced dimensions, fuel capacity (410L tops instead of 396L for D520 with empty wing tanks and 636L full) and weight but also a more aerodynamic and simplified structure.

The preseries models with 12Y-51 engine and 5 MGs (one in the nose) were to weigh 2150 kg at takeoff with 300L of fuel and only the wing MGs half-loaded (1200 rounds), while the full configuration with 410L of fuel and the nose MG with full ammo (2900 rounds) were to weigh 2295 kg. Wingspan 9.33m, total surface 13 m² with a thickness of 17%.

2 other preseries setup as low-altitude interceptors had 8.29m wingspan with 12.1m total surface.

The 2 other prototypes meant to prepare the series past the 200th plane with the HS-12Z engine had a total surface of 15 m² to maintain the 165 kg/m² wing loading.

The overall 100 Cx of a regular D520 was 3.52. The first batch of aerodynamic upgrades intended for the D524 and tested on a Vichy D520 gained 0.65 on the 100 Cx, while another batch (applied to M520T) saved another 0.2 on the 100 Cx (both of these batches also include more appropriate propellers and improved Szydlowski-Planiol superchargers). The tail obviously kept increasing in size along with power and weight.

The SE 520 Z, which is more representative of a D524 with aerodynamic upgrades, was calculated at some 3180kg at takeoff (3 cannons and 2 MGs in total).

The M520T was closer to a D551 derivative with 12Z engine and had a wingspan of 10.28m with a total surface of 16.26m², later increased to 10.597m and 17.324 m² respectively, and finally 10.646m wingspan. The weight of the final project was calculated at 3182.5 kg at takeoff for the day fighter mission, with a 20mm cannon in the nose and 6 MGs with 800 rounds each. It also introduced new high-lift flaps. And 780L of fuel.

Both the M520T and D551 wings also enabled the full storage of the wheels outside of the fuselage to reduce drag.

So in effect, the heaviest configuration and largest wing ever intended for a D520/551 derivative in the historical conditions were 3180 kg for day fighter missions and 17.3 m². With this setup the wing loading was 184 kg/cm².

My limited understanding is that these fighters were generally in the ballpark of Bf 109 F/G weight, wingspan and wing surface, and much smaller and lighter than the Spitfire and US fighters. Also somewhat similar to Soviet Yaks and MiGs.

 

[yulzari]

Are there any clues to be sought in the comparative performances in battles between the Dewoitine and the Hawker Hurricane?

Equally are there any in those of the Romanian Heinkel and the Soviet Air Force? Perhaps a link between them lies in a comparison between Romanian Heinkel112s and Romanian Hawker Hurricanes?

 

[Shortround6]

D520 wing: wingspan 10.2m, 16 m² surface, 20% thickness, 167 kg/m² wing loading

I don't know if that is accurate or not or where they measured it.
Hurricane was supposed to have 19% wing. P-40 used a 15% wing. MC 202 used a 18% wing.
But thickness is only one factor.
The later 17% thickness on the D 550 is better but the 13sq m wing is not.
French really loved small wings for less drag but that often meant problems with lift/turn.
Small wings means a larger change in wing loading when equipment changes are made compared to a larger wing aircraft.
Or the larger wing aircraft can be loaded up with more "stuff" for similar change in wing loading.

The French had a problem with their armament. It was heavy, especially compared to soviet guns/ammo.
There is no doubt the French could have developed/installed a belt feed on the 20mm Hispano gun but the 20mm Hispano was heavy and it's ammo was heavy.
using three 7.5mm machine guns to replace one 12.7mm gun is not much of a weight savings.

Original question was if the D.520 and He 112 could have equaled a late model Spitfire.
Spitfire VC can out turn the D-520 or any development and has about 33% more firepower than a one 20mm + six 7.5mm machine gun D.55X and then we can argue about speed and climb. A MK IX had the same firepower, a bit less turn but not much and a lot more speed and climb.

All of the small wing fighters (MC 202, Yaks, etc) have this problem. If you are happy with the single 20mm cannon and 1-2 heavy machineguns OR 4-6 light machine guns that opens things up somewhat.

I don't know what the wing thickness of the He 112 was but it sure doesn't look good in pictures. The short wingspan means low aspect ratio which is also not good for certain things (like cruise efficiency) but helpful for others (roll rate?). Stuffing a DB 601 might have been easy. Fitting in a DB 605 might have been tougher, it fits but the higher weight really pushes the wing loading up. Each 20mm MG/FF is about 1/2 the weight of a Hispano.
Data on Wiki is for a prototype which used a much bigger wing than the production models. In fact, slightly larger than a Spitfire instead of the 17 sq/m of the 112Bs
Hiding the 60 round drum for the MG/FF gun/s inside the wing without any bulges/bumps is quite a trick (or needs fat wing).

 

[Mfezi]

Elan Vital said:

D520 wing: wingspan 10.2m, 16 m² surface, 20% thickness, 167 kg/m² wing loading

I don't know if that is accurate or not or where they measured it.
Hurricane was supposed to have 19% wing. P-40 used a 15% wing. MC 202 used a 18% wing.
But thickness is only one factor.
The later 17% thickness on the D 550 is better but the 13sq m wing is not.

I'm curious about the source for the 20% thickness wing on the D.520. That is extremely, extremely thick. According to "The Incomplete Guide to Airfoil Usage" that we have been maintaining at UIUC, the D.520 used a NACA 0018.7 airfoil at the root and a NACA 23010 at the tip. That implies a 18.7% thick root airfoil and a 10% thick tip airfoil. These numbers are confirmed by the "Caracteristiques D.520" document published on this site here: Dewoitine D.520 Manuals
It also says root 18.7% and 10% at the tip.

 

[Elan Vital]

I'm curious about the source for the 20% thickness wing on the D.520. That is extremely, extremely thick. According to "The Incomplete Guide to Airfoil Usage" that we have been maintaining at UIUC, the D.520 used a NACA 0018.7 airfoil at the root and a NACA 23010 at the tip. That implies a 18.7% thick root airfoil and a 10% thick tip airfoil. These numbers are confirmed by the "Caracteristiques D.520" document published on this site here: Dewoitine D.520 Manuals
It also says root 18.7% and 10% at the tip.

I don't recall but this source is certainly more accurate. Meanwhile, Cuny says 17% at the root and 10% at the tip for D551.

 

[Admiral Beez]

*As long as the 12Z uses the bore/stroke of the 12Y, it will probably never be as efficient as the likes of the Merlin.

Then we must get the French the Dewoitine D.521, replacing the standard Hispano-Suiza inline engine with a British Rolls-Royce Merlin III.

 

[Shortround6]

*As long as the 12Z uses the bore/stroke of the 12Y, it will probably never be as efficient as the likes of the Merlin. If the French engineers play their cards well, they could benefit from high octane fuel, excellent US tooling and good materials and eventually outperform the DB 601/605 with the 12Z.

Bore and stoke of the 12Y & Z..............150 x 170 mm
Bore and stroke of the Griffon...............152 x 168 mm
Bore and stroke of the Jumo 213.........150 x 165 mm

It is not the bore and stroke, it is strength of the crankcase, crankshaft, rods and the size of the bearings limiting the rpm and cylinder pressures.
The designers of the Griffon and Jumo 213 were not dumb. There were very good reasons why their engines were as heavy as they were.

 

[Steamed_Banana]

Both aircraft had combat histories through the war. He was known for service in the Spanish Civil War which was middling - one kill claim and some ground attack sorties. Hungary used a couple of He 112s in border skirmishes with Romania, and Romania also used some (about six IIRC?) in action against Hungary, and then later in the Soviet union where they achieved some successes initially against I-16s, but later took heavy losses when used as ground attack. The aircraft was generally deemed underpowered and lacking in agility, and had no protection so was particularly bad for ground attack, and somewhat difficult to maintain.

D.520s did poorly in the Battle of France but that is almost certainly because they arrived mostly during the fighting, without any time for training, pilot familiarity, or technical shakeout, and in many cases lacking things like certain instruments or some of their ammunition etc. Many were destroyed on the ground and those that got into the air did poorly.

However, that was not actually the end for the D.520.

Several squadrons of D.520s were used by Vichy forces in a short but fairly intense war with the British and Commonwealth forces in Syria and the Horn of Africa in 1940. They proved fairly capable against Hurricanes and Fulmars, shot down several Blenheims, and even more hapless Wellesleys, plus Hawker Harts and Junkers 86 used by the SAAF. But they did poorly against Gladiators (!) and especially 3 RAAF Tomahawks. Several of these engagements are covered in videos I posted to another thread. The D.520 was the main French fighter in this area, with only a few MS.406s and some Potez 63.11 heavy fighters augmenting them (barely at all). Shores also has a total of the British vs losses in the air in his book, I'll go find those and post them tomorrow. I think it was somewhere around 30 on each side. Most of the French aircraft losses were to strafing and bombing of their airfields, as they did not seem to use revetments or have much AAA protection on the fields.

D.520s were in action again for Vichy forces when the Allies invaded Morocco during Torch in November 1942. They had a very short but quite sharp engagement with US Navy and Air Force, as well as some RAF and FAA aircraft. D.520s and Hawk 75s took a fairly heavy toll, and between them were responsible for about 25 US Navy aircraft, mainly F4F fighters and SBD bombers, and a handful of British aircraft, while losing rough 15 fighters. Once again they lost a lot on the ground, about 70+ aircraft, due to having almost no protection on their airfields.

The Italians used D.520s in four squadrons which were effectively tasked with point defense in Italy in late 1943 and 44, mainly around Naples, and they made some claims with them including one B-24 IIRC.

The Bulgarians used D.520s claiming about a 10-12 Allied aircraft, mainly B-24s and a couple of P-38s in Nov and Dec of 1943, though it's hard to be sure which aircraft types scored which victories.

D.520 was agile, was pretty well armed with the hub mounted 20mm cannon, had armor, had decent range (much better than a Hurricane or early Spitfire) was reasonably fast (faster than a Hurricane especially with tropical filters, and that was with an 860 hp engine) and had a functional radio, though it was apparently somewhat hard to fly. The French were planning to put a much higher-rated engine in it though obviously that never came through. But with say a 1,000 hp engine, which the French definitely thought was going to happen, it could have been quite formidable. Whether that was feasible depends on if you belive in Hispano Suiza, I do personally.

Of the two, I think it's no contest the D.520 was much better. The He 112 was never more than a prototype really, not a fully fleshed out design.

 

[Steamed_Banana]

All of the small wing fighters (MC 202, Yaks, etc) have this problem. If you are happy with the single 20mm cannon and 1-2 heavy machineguns OR 4-6 light machine guns that opens things up somewhat.

MC 202 and later model Yak fighters were quite good in spite of having relatively small number of guns. Having the guns in the nose helped a lot with accuracy even with reduction gears in place (i.e. aside from the motorkanone)

I don't know what the wing thickness of the He 112 was but it sure doesn't look good in pictures. The short wingspan means low aspect ratio which is also not good for certain things (like cruise efficiency) but helpful for others (roll rate?). Stuffing a DB 601 might have been easy. Fitting in a DB 605 might have been tougher, it fits but the higher weight really pushes the wing loading up. Each 20mm MG/FF is about 1/2 the weight of a Hispano.
Data on Wiki is for a prototype which used a much bigger wing than the production models. In fact, slightly larger than a Spitfire instead of the 17 sq/m of the 112Bs
Hiding the 60 round drum for the MG/FF gun/s inside the wing without any bulges/bumps is quite a trick (or needs fat wing).

Anectotally D.520 had a good roll rate, though rate of climb was 2800 fpm initially and 4.5 m to 4,000 meters which is about average for an early WW2 fighter, but rather good for an 860 hp engine.

 

[Steamed_Banana]

I would also note the to me perpetually amusing fact that when this comes up about 'small fighters' being supposedly problem designs, the Bf 109 seems to always be forgotten, even though with it's wingspan of 32' 6.5" / 9.92 m it was actually a bit smaller than a MC 202 (wingspan 34' 9" / 10.58 m) and the Yak 1 (32' 10" / 10 m).

 

[Shortround6]

MC 202 and later model Yak fighters were quite good in spite of having relatively small number of guns. Having the guns in the nose helped a lot with accuracy even with reduction gears in place

A lot this depends on where they were fighting and against who.

I would also note the to me perpetually amusing fact that when this comes up about 'small fighters' being supposedly problem designs, the Bf 109 seems to always be forgotten, even though with it's wingspan of 32' 6.5" / 9.92 m it was actually a bit smaller than a MC 202 (wingspan 34' 9" / 10.58 m) and the Yak 1 (32' 10" / 10 m).

There are design problems. You can't repeal the laws of physics.

MC 202 had problems fitting in more guns, also fuel. One problem is space (volume) in the wing to fit 'stuff'. 2nd problem is the added weight of the "stuff" (not all of which had to be fitted into the wing) but wing has to support the weight, which affects wing loading which affects maneuver and landing/take-off performance.
Over 3-4 years different countries accepted certain trade-offs. Some more than others and for different reasons.
YAK-1 faced many of the same problems.

Trying to shoot down fighters is one thing, trying to shoot down bombers is usually harder. Not always but depending on your opponents to keep delivering roast turkeys on serving trays so your poorly armed fighters remain successful is poor planning or forced planning (you have no alterative).
Bf 109 shows part of the problem with the famous "gun" boats. Adding under wing 20mm cannon made them good bomber busters and this is well before the B-17s showed up in numbers. Needed squadrons of anti-escort fighters to accompany squadrons of bomber busters because the bomber busters were at a disadvantage in fighter vs combat?

Small fighter of high performance has traded fire power for performance (assuming similar engines). It may get more firing opportunities. Turning those firing opportunities into destroyed enemy aircraft is harder. Small fighters generally hold less fuel, and small size only goes so far in keeping desired range/endurance. A large fighter offers the opportunity to fit in more fuel as engine power is increased. Opportunity is sometimes not taken up. See the hundreds of posts on adding fuel to the Spitfire. However the Spitfire had the space/volume to go from 84imp gal to 130-150imp gal internal if desired (not planned for originally) Adding 45-50 imp gals to the small fighters was difficult or impossible without major modifications, like new wing structure in the YAKs.

P-40 offered all kinds of room inside the plane to put "stuff". Wing was big enough. They never got a powerful enough engine to actually get the whole thing to come together.
The size of the plane was too tempting, and they loaded it with too many guns/too much ammo. P-40 could also hold 50% more fuel internally than a 109 or Yak 1.

 

[Gilder]

Personally I believe that the D520 lacked real development due to its limited size and equally limited performance in combat. The He 112 had a good performance with a fairly underpowered engine which I understand was considerably better that the comparably powered Me109D, and had a lot of potential which wasn't realised.

From the French side the Bloch 152 / 155 again had potential but unless France had the opportunity to equip it with a modern (Merlin equivalent) engine, its potential would never be realised. That said a version with the Supercharged Gnome-Rhone 14R engine was flown in March 1942 known as the Bloch 157

The Bloch 157 had the following stats-

Max Speed 441mph at 25,750 ft
Range 683 mph
Time to 26,000 ft 11 minutes

Note that she wasn't armed for the above flight and I don't know about armour or other military equipment, but the proposed armament was 2 x 20mm and 2 x Lmg. In 1943 she was given to the Luftwaffe who took the engine out for tests and she never flew again.

 

[Elan Vital]

A lot this depends on where they were fighting and against who.

There are design problems. You can't repeal the laws of physics.

MC 202 had problems fitting in more guns, also fuel. One problem is space (volume) in the wing to fit 'stuff'. 2nd problem is the added weight of the "stuff" (not all of which had to be fitted into the wing) but wing has to support the weight, which affects wing loading which affects maneuver and landing/take-off performance.
Over 3-4 years different countries accepted certain trade-offs. Some more than others and for different reasons.
YAK-1 faced many of the same problems.

Trying to shoot down fighters is one thing, trying to shoot down bombers is usually harder. Not always but depending on your opponents to keep delivering roast turkeys on serving trays so your poorly armed fighters remain successful is poor planning or forced planning (you have no alterative).
Bf 109 shows part of the problem with the famous "gun" boats. Adding under wing 20mm cannon made them good bomber busters and this is well before the B-17s showed up in numbers. Needed squadrons of anti-escort fighters to accompany squadrons of bomber busters because the bomber busters were at a disadvantage in fighter vs combat?

Small fighter of high performance has traded fire power for performance (assuming similar engines). It may get more firing opportunities. Turning those firing opportunities into destroyed enemy aircraft is harder. Small fighters generally hold less fuel, and small size only goes so far in keeping desired range/endurance. A large fighter offers the opportunity to fit in more fuel as engine power is increased. Opportunity is sometimes not taken up. See the hundreds of posts on adding fuel to the Spitfire. However the Spitfire had the space/volume to go from 84imp gal to 130-150imp gal internal if desired (not planned for originally) Adding 45-50 imp gals to the small fighters was difficult or impossible without major modifications, like new wing structure in the YAKs.

P-40 offered all kinds of room inside the plane to put "stuff". Wing was big enough. They never got a powerful enough engine to actually get the whole thing to come together.
The size of the plane was too tempting, and they loaded it with too many guns/too much ammo. P-40 could also hold 50% more fuel internally than a 109 or Yak 1.

Interestingly enough the D520 actually carried a greater fuel capacity than the regular Spitfire (87 imp gal in the fuselage and 26.4 in each wing), the wings not always being filled for certain missions. The D551 carried 410L or 90.2 imp gal, or 300L (66 imp gal) during certain missions. But it is true that this capacity was probably the maximum you could really physically fit in them, while the Spitfire had potential to carry more (and P-51 carried far more).

Personally I believe that the D520 lacked real development due to its limited size and equally limited performance in combat. The He 112 had a good performance with a fairly underpowered engine which I understand was considerably better that the comparably powered Me109D, and had a lot of potential which wasn't realised.

From the French side the Bloch 152 / 155 again had potential but unless France had the opportunity to equip it with a modern (Merlin equivalent) engine, its potential would never be realised. That said a version with the Supercharged Gnome-Rhone 14R engine was flown in March 1942 known as the Bloch 157

The Bloch 157 had the following stats-

Max Speed 441mph at 25,750 ft
Range 683 mph
Time to 26,000 ft 11 minutes

Note that she wasn't armed for the above flight and I don't know about armour or other military equipment, but the proposed armament was 2 x 20mm and 2 x Lmg. In 1943 she was given to the Luftwaffe who took the engine out for tests and she never flew again.

The Bloch 152/155 airframe was limited to 1300 hp maximum, hence the changes when going to the 157, so they didn't really have much potential beyond 1940-41, as Bloch did anticipate. The intended armament was actually 2x20mm and 4x7.5mm MGs.

I believe you meant to say "development potential" in your sentence about D520. Yet the French projects before and after the Armistice indicate that the D520 airframe could handle powerful engines with the normal structural changes that affected other fighter aircrafts. Even ignoring the intended switch to D551-style airframes, it could at least broadly match the development potential of a Bf 109 and other small fighters, even if it would never have the advantages of big fighters.

 

[Steamed_Banana]

A lot this depends on where they were fighting and against who.

Italian and Russian fighters were more specialized, no doubt about it. But they worked within their own systems - the Soviets had no trouble fighting the Japanese at the end of the war.

The Macchi C.202 also incidentally carried slightly more fuel than the Bf 109 - 460 liters vs 400, and had a bit better range on internal fuel.

It is generally true though that the larger aircraft, once they were fully debugged and functioning per their design goals, were probably more versatile, but that (versatility vs specialization) is another design approach with it's own tradeoffs.

There are design problems. You can't repeal the laws of physics.

Yeeeeeah, but it's funny how the tradeoffs for one type are always presented as problems while those for another are pretty well glossed over.

In the US, we favor large aircraft because that is the route US aircraft designers went - MOAR stuff, more fuel guns armor etc. But there was, historically, more than one way to skin a cat and we all know that the US approach, and specific especially later war US designs that were very large while eventually successful were not necessarily the ultimate WW2 warplanes some of us grew up thinking they were.

Same for the biggest British fighters like the Typhoon, Tempest, Firefly etc.

Smaller and lighter aircraft were better in some ways than bigger and heavier ones, and vice versa. Both approaches could be and were made to work effectively.

As I said before, I think it's particularly amusing that when this debate spews up in which people criticize the smaller fighters made by the French, Italians, Soviets, and Japanese, the German planes like the Bf 109 are mysteriously forgotten, as if that crooked cross on the tail somehow makes it Über! You know it doesn't really work like that right?

The Bf 109 is generally acknowledged as certainly one of the top five fighters of the war, and though it definitely did have some fairly significant inherent limitations, these tend to be glossed over. It is also simultaneously true that the Bf 109 was made to be effective throughout the war, and successfully adapted to a wide range of conditions and different enemy aircraft and tactics.

MC 202 had problems fitting in more guns, also fuel. One problem is space (volume) in the wing to fit 'stuff'. 2nd problem is the added weight of the "stuff" (not all of which had to be fitted into the wing) but wing has to support the weight, which affects wing loading which affects maneuver and landing/take-off performance.

They could have put cannon in the prop hub like in the 109 (with the same engine) and as the Italians did with the G.55, and the Re 2005, and with a prototype variant of the C.205 (the C.205N "Orione").

I don't think it was any more lacking in space than the Bf 109, certainly. As for fuel, it was a small fighter but with an external tank(s) it was as good in this sense as the Bf 109 and the Spitfire. In fact maybe better potentail for that because it could carry two wing tanks instead of one fuselage tank like the 109.

Over 3-4 years different countries accepted certain trade-offs. Some more than others and for different reasons.
YAK-1 faced many of the same problems.

I agree but I think the tradeoffs are just that - you get some advantages and some disadvantages. It's a very different thing than being just a "design problem" with no upside.

At the risk of belabouring the obvious, smaller airframes and wings mean you don't need as powerful of an engine to go fast and climb and accelerate well. As we know, smaller engines typically, all other things being equal, require less fuel.

The US had plenty of fuel available and robust logistics to deliver it where it was needed. But the US was fairly unique in this sense. For many countries, fuel efficiency was a major benefit of a given aircraft design, as we see most prominently with the Japanese especially the excellent A6M.

Smaller aircraft also tend to be a little bit harder to hit. They are often more nimble. Lighter aircraft typically climb better.

Trying to shoot down fighters is one thing, trying to shoot down bombers is usually harder. Not always but depending on your opponents to keep delivering roast turkeys on serving trays so your poorly armed fighters remain successful is poor planning or forced planning (you have no alterative).
Bf 109 shows part of the problem with the famous "gun" boats. Adding under wing 20mm cannon made them good bomber busters and this is well before the B-17s showed up in numbers. Needed squadrons of anti-escort fighters to accompany squadrons of bomber busters because the bomber busters were at a disadvantage in fighter vs combat?

You are equating the very specific issue of dealing with 'heavy daytime bombers' with 'bombers' in general. The US was basically the only country in the world during WW2 which fielded heavy, large, heavily armed daytime bombers, and these were not a major factor in the war until very late in 1943 or early 1944. It's debatable whether any kind of fighter could have coped with the problems posed by thousands of B-17s, B-24s, and (especially) B-29s. Probably jets were the best answer to that, and they likely should have been developed more quickly as fighters by the Germans. It seems like they could have been.

But for most WW2 bombers, lets be real. Fighters like the Yak 1 had no trouble shooting down Ju 88s, He 111s, Ju 87s etc., nor did MC 202s have a major challenge with Bristol Blenheims, Martin Marylands, Fairey Swordfish, Fairey Albacores, Wellingtons, or for that matter B-25s and B-26s. If they did have a bit more trouble with Bostons and Baltimores that was mainly due to speed more than anything else and because they were protected by heavy escorts at a time when the Axis was starting to be outnumbered.

Small fighter of high performance has traded fire power for performance (assuming similar engines). It may get more firing opportunities. Turning those firing opportunities into destroyed enemy aircraft is harder.

A lot of that comes down to training and heavier armament isn't necessarily the solution. Look how well Ki-43s did against light and medium US and British bombers and even B-24s.

Small fighters generally hold less fuel, and small size only goes so far in keeping desired range/endurance.

I'd call the A6M a small fighter...

A large fighter offers the opportunity to fit in more fuel as engine power is increased. Opportunity is sometimes not taken up. See the hundreds of posts on adding fuel to the Spitfire. However the Spitfire had the space/volume to go from 84imp gal to 130-150imp gal internal if desired (not planned for originally) Adding 45-50 imp gals to the small fighters was difficult or impossible without major modifications, like new wing structure in the YAKs.

Spitfire isn't really any bigger than a Yak-1 or a MC 202, except in the wing, and the Spitfire wing is too thin to hold a lot of fuel. They could have crammed more fuel into the Yaks - in fact they did make a long-ish ranged Yak 9, or into the MC 202s - in fact they did increase the range of the MC 205 by about 100 miles.

P-40 offered all kinds of room inside the plane to put "stuff". Wing was big enough. They never got a powerful enough engine to actually get the whole thing to come together.
The size of the plane was too tempting, and they loaded it with too many guns/too much ammo. P-40 could also hold 50% more fuel internally than a 109 or Yak 1.

I mean, the P-51 had the same size wing. But again there are tradeoffs.