Advanced French Fighters vs 1942/1943 contemporaries (2 Viewers)

[Shortround6]

A lot to unpack here and may take several tries.

That is indeed significant, but the Swiss achieved it in 2 years, and for all their skill, there just aren't that many Swiss (and even fewer as a percentage of their industrial base, working on aircraft engines).

It seems like the 12Y varied a fair bit in weight, with early versions weighing around 415-440 kg.

That is indeed significant, but the Swiss achieved it in 2 years, and for all their skill, there just aren't that many Swiss (and even fewer as a percentage of their industrial base, working on aircraft engines).

It seems like the 12Y varied a fair bit in weight, with early versions weighing around 415-440 kg. The 12Y-31 in the original MS.406 weighed 468 Kg, and the 12Y-51 which was the original basis for the YS-2, weighted 492 kg. So which of these are comparing the YS-2 with? I couldn't find the weight for the YS listed.

The older 12Y's had a letter code. Which changed a bit in 1932. In 1931 a "c" in the string of letters meant 'compressor' or supercharger. In 1932 they shifted to "s" meaning supercharged to about 4000 meters. If there was a "g" instead of the "s" the engine used a 200 mm impeller in the supercharger instead of 240mm impeller and was rated at 2000 meters instead of 4000. An engine than neither the "s" or the "g" had no supercharger. The letter "r" meant reduction gear. so the 415 and 440 kg engines had no superchargers,
The Change from the letter "B" to the letter "D" signifies the addition of a hydraulic pump device for the Hispano-Suiza/Hamilton variable pitch propellers. And that pretty much gets us up to the 470kg engines.

But the important bit is that the 12Z was already at least at a late enough of a stage to fly prototype aircraft with.

Yes, and they flying a Prototype F4U in 1940. Lets not go into the American flat 12s and the Lycoming IV-1430.

The French apparently had 100/130 fuel by the way, I don't know if that was coming from the British or what.

No they did not.
The British didn't even have 100/130 fuel in the summer of 1940. Or more accurately, they had some but they didn't quite know were it was. They had fuel that was 100 octane lean and it was better than 100 octane running rich but they didn't quite know how much better because the Performance Number scale (PN) had not be developed yet and test procedures had not been developed yet. They might have some batches of fuel that would test to 100/130 once they had the scale and procedures and other batches that would test at 115-120.
US Fuel was 100/100???. when tested later there were few batches that actually performed worse running rich than running lean. Like 100/98.
1940 was a really big year for aviation fuel for the Allies. It also took a lot of 1941 to sort through things and come up with acceptable standards for both countries.

France had a vastly larger and more developed aviation industry, population, much more resources in terms of raw materials, power etc., better available fuel etc.

The Swiss were not quite as backwards as it might seem. They built a lot of precision machine tools for export. They had the first stationary gas turbine engine (electrical generation) and built their own electric locomotives and steam engines. They also had a small company called Oerlikon and few other gun companies, like Sig.
The Swiss were not interested in building either planes or engines by the hundreds. Which makes tooling up for small scale production easier and you don't need anywhere near the number of people in the shop/s.
There is also a problem with trying to improve engines and aircraft while simultaneously trying to equip a factory for mass production. Maybe you can buy and install 80% or 90% of the machine tools with no problems but some times you have to wait for certain machines to be delivered or you have order one or two new machines if you change certain parts too much late in the development process. RR did all of the development work and most of the small scale production work at headquarters. The more outlying factories built engines in large production runs/batches.

Famous story about P&W and the Napair Sabre engine. Napier, with the aid of Bristol (forced at practically bayonet point) had figured out the 'secret' to making sleeve valves. Now to make the sleeve valves in the quantity desired at the quality desired (scrap rate) they decided they needed 6 (?) large centerless grinders from a US company. The Grinders were found, packed and shipped on the Queen Mary (?) for rapid shipment to England where they were unloaded, sent to Napiers and all was well in sleeve valve land.
Things were not so good back in the USA where it took Strand (the Grinder company ?) about 6 weeks to build/replace the grinders and the completion of the P&W Kansas city plant, dedicated to making the R-2800 C series engines (P-47M & N, F4U-4s, and F8-1) was delayed 6 weeks and a 6 week delay might have meant several hundred fewer R-2800 engines of those types in 1944.
even the US did not have an inexhaustible supply of machine tools.

Had H-S had a problem. Too much had rested on Birkigt's shoulders. He was not only responsible for dozens of engine designs, he designed much of special tooling to make the engines. When he "retired" in 1936 they needed people to design any new tooling and going to 3 or 4 valve heads was going to require a lot of new tooling. It was possible to perform some the valve seat work on the V-12 engines using some of the machinery that Birkigt had designed to make the WW I V-8 engines.

This turns into a real problem with 12Z engines as there not a lot of agreement as to what was changed and in which factories, at east in English sources.

A lot also depends on when/where the stabilization of the lines takes place. H-S was evacuating machinery to a factory just north of the Spanish border and trying to set up a factory in tunnels outside of Bordeaux. So do you have 3 factories or 2 or sort of two 3/4 factories indifferent places?

 

[Steamed_Banana]

including to pretend that the HS404 cannon was fit for service so early in the war.

Well, it was the main armament of the Dewoitine D.501, D.510 (these going back to 1938, by the way) and D.520, MS 406 fighter, Bloch 152, Breguet 693, and several other French made aircraft which saw combat during the Battle of France and for a long time afterword, including for example on the MS.406 while flown by the Finns. The MS 404 was also used

I'm not sure the British history with their license built version of the HS 404 is the same as the French history of their use of that weapon. The US version (licensed from the British) did not work well, as I noted. Nevertheless it was used in the P-38.

Do you have any specific data about problems with the HS.404 in French service? I'm ready to learn.

Many early cannon and heavy machine guns had a variety of problems in the early war, but that doesn't mean they were not used successfully in spite of it.

The MS 404 as used by the French had the 60 round drum. Hispano-Suiza was already working on a belt fed version in 1940 (such as the British produced for the Spitfire Mk VC among others) but that was halted by the Germans.

 

[Bretoal2]

The older 12Y's had a letter code. Which changed a bit in 1932. In 1931 a "c" in the string of letters meant 'compressor' or supercharger. In 1932 they shifted to "s" meaning supercharged to about 4000 meters. If there was a "g" instead of the "s" the engine used a 200 mm impeller in the supercharger instead of 240mm impeller and was rated at 2000 meters instead of 4000. An engine than neither the "s" or the "g" had no supercharger. The letter "r" meant reduction gear. so the 415 and 440 kg engines had no superchargers,
The Change from the letter "B" to the letter "D" signifies the addition of a hydraulic pump device for the Hispano-Suiza/Hamilton variable pitch propellers. And that pretty much gets us up to the 470kg engines.

ALL 12Y versions had a native supercharger and prop reduction gear.

The French system including letters such as "r" for reducteur and "s" for suralimentation (plus a, b,c,d..... for different versions of a same basis) was abandonned in 1936 and superseded with numeral system. So 12Ycrs = 12Y 31, and so on.

The 12Y-89 never existed, 89 was the internal study number for a 4 valves and differential scavenge system derivative of the 12Y. Its commercial name was.... 12Z !

The 12Z-17 only ran in 1947.

 

[Shortround6]

The three 20mm cannon on these French fighters however, is not a fantasy. That was the armament of the Swiss D.3802, and of the prototype VG 39bis.

Swiss had several years to sort things out, not months.

Whether that could be done with a Martlet or a P-40 or not, I can't say, but the P-40D (the earliest Mark Kittyhawk I) did have provision for 20mm cannon originally.

Yes it did. Kind of, sort of, if you stand back far enough and squint real hard looking into the sun
The "provisions" consisted of some internal brackets that were in the gun bay/s. Some slots cut in the bottom wing panel and some optional brackets stored someplace that allowed for the ground crew to cut part of the bottom wing panel out and sling the 20mm Hispano gun under the wing.
There were reasons why nobody tried to use 20mm guns on P-40Ds.
They did a whole lot better with the P-51As

The limitation on the US use of the 20mm cannon seems to be due to the poor quality of the US made 20mm cannons, which were not very reliable. But the HS 404 was a pretty good cannon, albeit with it's own problems. It was good enough for use with a Spitfire and a Hurricane (among other aircraft) in wing mounts.

Again, things varied with time. The US guns were bad and while some were modified later they may never have been issued (or were modified again and use in the 1950s or 60s as ground guns) Spitfires used several very different installations. Hurricanes used one. Hurricanes rarely operated at high altitudes where heating was a problem.

 

[Shortround6]

ALL 12Y versions had a native supercharger and prop reduction gear.

Just going by chart on page 180 of "Hispano Suiza in Aeronautics" by Manuel Lage and the text on pages 180 and 181.
What is listed for advertising may not what actually built.

 

[Steamed_Banana]

Yes, and they flying a Prototype F4U in 1940. Lets not go into the American flat 12s and the Lycoming IV-1430.

12Z does not look that far away to me, let alone unobtainable, but we won't ever know.

No they did not.
The British didn't even have 100/130 fuel in the summer of 1940. Or more accurately, they had some but they didn't quite know were it was. They had fuel that was 100 octane lean and it was better than 100 octane running rich but they didn't quite know how much better because the Performance Number scale (PN) had not be developed yet and test procedures had not been developed yet. They might have some batches of fuel that would test to 100/130 once they had the scale and procedures and other batches that would test at 115-120.
US Fuel was 100/100???. when tested later there were few batches that actually performed worse running rich than running lean. Like 100/98.
1940 was a really big year for aviation fuel for the Allies. It also took a lot of 1941 to sort through things and come up with acceptable standards for both countries.

Some of the tests done with the later model VG.33 and Dewoitine prototypes were listed as being with 100/130 fuel, though I have no idea where they got it or whether it's correct. That's why I wrote "apparently", I don't know the particulars. It could be they only had a small amount which was enough for some testing. France had an oil industry too though, and big oil company with plenty of refineries etc.

The Swiss were not quite as backwards as it might seem. They built a lot of precision machine tools for export. They had the first stationary gas turbine engine (electrical generation) and built their own electric locomotives and steam engines. They also had a small company called Oerlikon and few other gun companies, like Sig.

I never said the Swiss were backwards, I said they were and are small, which is a very different thing. France had plenty of innovations too, including that HS 404 cannon and the 12Y engine which you may disparage, but both of which were widely copied and in heavy use during WW2, as were other French aircraft engines.

A lot also depends on when/where the stabilization of the lines takes place. H-S was evacuating machinery to a factory just north of the Spanish border and trying to set up a factory in tunnels outside of Bordeaux. So do you have 3 factories or 2 or sort of two 3/4 factories indifferent places?

I wasn't thinking about any of that, just speculating on what was both possible and apparently likely if France hadn't fallen. Where the lines ended up would yes definitely affect the possibilities of continued production.

 

[Steamed_Banana]

Swiss had several years to sort things out, not months.

Yes and France had ten times the population and a vastly more developed aviation industry

Yes it did. Kind of, sort of, if you stand back far enough and squint real hard looking into the sun
The "provisions" consisted of some internal brackets that were in the gun bay/s. Some slots cut in the bottom wing panel and some optional brackets stored someplace that allowed for the ground crew to cut part of the bottom wing panel out and sling the 20mm Hispano gun under the wing.
There were reasons why nobody tried to use 20mm guns on P-40Ds.
They did a whole lot better with the P-51As

That said, I don't think the P-40 would be any more difficult to mount a 20mm cannon into the wing than an MS 406, VG.33, or D.520 derivative, or the Bloch 152, or a Hurricane etc. If they were using these aircraft for a long time they might re-equip them with their own locally made guns, as the Soviets did in some cases. And HS 404 is the logical choice.

Again, things varied with time. The US guns were bad and while some were modified later they may never have been issued (or were modified again and use in the 1950s or 60s as ground guns) Spitfires used several very different installations. Hurricanes used one. Hurricanes rarely operated at high altitudes where heating was a problem.

Well the French fighters were limited in their altitude capabilities. And the fighting may well have been largely tactical so down low.

 

[Elan Vital]

FYI, there is a fighter project I didn't know about until yesterday that does not fit the Dewoitine, Arsenal or Bloch mainlines.

This is the Potez C1-40, which is partially extrapolated from the Potez 230 lightweight fighter (esp the elliptical wing and its structure), made for a program by Albert Caquot (the wartime air minister up to early 1940), visibly a high altitude fighter.

Scans of the relevant docs on it are here: POTEZ 40 C1, C2 + POLICE TOE

The main takeaways is that, aside from some obscure pre-Fall Arsenal designs, and Vichy-era designs, it is rather large and heavy, closer to Anglo-American fighters. It is also reportedly longer ranged than most French designs (1800 km max radius). Uses a pressurized canopy and a 1200-1300 hp HS-12Z with one turbocharger per bank, for a target speed of 650 kph at 10 000m. The armament is also on the heavy side since it's meant to carry a nose 20mm cannon, and 3 7.5mm MGs per wing, or one nose MG and 4 MGs per wing (the only French fighter with that armament setup).

Now, it only was at the mockup and aerodynamic testing stage as of mid 1940 so it's probably gonna be a very late war fighter and may even get the fate of superprops, but it may have offered sufficiently different characteristics from the other French fighters and their evolution to be accepted down the line.

 

[Steamed_Banana]

FYI, there is a fighter project I didn't know about until yesterday that does not fit the Dewoitine, Arsenal or Bloch mainlines.

This is the Potez C1-40, which is partially extrapolated from the Potez 230 lightweight fighter (esp the elliptical wing and its structure), made for a program by Albert Caquot (the wartime air minister up to early 1940), visibly a high altitude fighter.

Scans of the relevant docs on it are here: POTEZ 40 C1, C2 + POLICE TOE

The main takeaways is that, aside from some obscure pre-Fall Arsenal designs, and Vichy-era designs, it is rather large and heavy, closer to Anglo-American fighters. It is also reportedly longer ranged than most French designs (1800 km max radius). Uses a pressurized canopy and a 1200-1300 hp HS-12Z with one turbocharger per bank, for a target speed of 650 kph at 10 000m. The armament is also on the heavy side since it's meant to carry a nose 20mm cannon, and 3 7.5mm MGs per wing, or one nose MG and 4 MGs per wing (the only French fighter with that armament setup).

Now, it only was at the mockup and aerodynamic testing stage as of mid 1940 so it's probably gonna be a very late war fighter and may even get the fate of superprops, but it may have offered sufficiently different characteristics from the other French fighters and their evolution to be accepted down the line.

That's very interesting, could you post an image? The site seems to be restricted unless you are signed up.


There are a few other very interesting and somewhat promising if not beautiful designs, of which my favorite is probably this one

SNCASE SE.100 - Wikipedia

en.wikipedia.org

Only one prototype built, but it made 580 km / 360 mph at 21,000 ft / 6500m , had a range of 1300 km / 810 miles, and a rather brutal armament of 4 x 20mm cannon in the nose, plus another 20mm for the defender. This one was powered by two Gnome-Rhone 14N with 1081 hp each.

The production version was supposed to have more powerful Gnome-Rhone 14N-20/21 (as used on the successful LeO 451 bomber) and 6 x 20mm in the nose and 2 more in the rear turret plus two more in the belly (?) I think as defensive guns, and a lot of additional fuel where you see the windows on the fuselage center, so presumably longer range though I don't know how much longer.

I haven't been able to find out much about the prototype testing, so I don't know about handling, and I couldn't find out much about rate of climb. It was heavy (7,500 kg loaded) and has a pretty high wing-loading so it would not have been a dog fighter. I just love this design because it's so weird and innovative. It may not have been viable but seems like it could have been in the ballpark of something like a Westland Whirlwind, Beaufighter, or Bf 110 (and it was a good bit faster than the latter, if we can believe the alleged test results. With more powerful engines it should have been faster still)

Been trying to get a model kit of one of these for years but it's always too expensive ...


France also had several of those 'light fighters' like the Potez 230 and the Caudron 714 but these didn't do so great and it's a whole 'nother ball of wax to determine if any of those could have been made viable. So I just left them out of the discussion. Light fighters are kind of a discussion of their own worth having, IMO.

 

[SaparotRob]

That's very interesting, could you post an image? The site seems to be restricted unless you are signed up.


There are a few other very interesting and somewhat promising if not beautiful designs, of which my favorite is probably this one

View attachment 851098

View attachment 851099

View attachment 851100

SNCASE SE.100 - Wikipedia

en.wikipedia.org

Only one prototype built, but it made 580 km / 360 mph at 21,000 ft / 6500m , had a range of 1300 km / 810 miles, and a rather brutal armament of 4 x 20mm cannon in the nose, plus another 20mm for the defender. This one was powered by two Gnome-Rhone 14N with 1081 hp each.

The production version was supposed to have more powerful Gnome-Rhone 14N-20/21 (as used on the successful LeO 451 bomber) and 6 x 20mm in the nose and 2 more in the rear turret plus two more in the belly (?) I think as defensive guns, and a lot of additional fuel where you see the windows on the fuselage center, so presumably longer range though I don't know how much longer.

I haven't been able to find out much about the prototype testing, so I don't know about handling, and I couldn't find out much about rate of climb. It was heavy (7,500 kg loaded) and has a pretty high wing-loading so it would not have been a dog fighter. I just love this design because it's so weird and innovative. It may not have been viable but seems like it could have been in the ballpark of something like a Westland Whirlwind, Beaufighter, or Bf 110 (and it was a good bit faster than the latter, if we can believe the alleged test results. With more powerful engines it should have been faster still)

Been trying to get a model kit of one of these for years but it's always too expensive ...


France also had several of those 'light fighters' like the Potez 230 and the Caudron 714 but these didn't do so great and it's a whole 'nother ball of wax to determine if any of those could have been made viable. So I just left them out of the discussion. Light fighters are kind of a discussion of their own worth having, IMO.

I like this plane. It looks like a Lockheed Hudson with its tail tucked between its legs.

 

[bf109xxl]

I like this plane. It looks like a Lockheed Hudson with its tail tucked between its legs.

And what does this one look like?

 

[Elan Vital]

The pictures from the Potez C1-40 came from the Collection Histoire de l'Aviation n°20, relevant pages (that were posted by the author of the SPF thread) attached here.

You will note the spec table, with planned/estimated specs by Potez on the left and the requirements (maximum for weight and dimensions, minimum for performance) on the right.

 

[Shortround6]

That said, I don't think the P-40 would be any more difficult to mount a 20mm cannon into the wing than an MS 406, VG.33, or D.520 derivative, or the Bloch 152, or a Hurricane etc. If they were using these aircraft for a long time they might re-equip them with their own locally made guns, as the Soviets did in some cases. And HS 404 is the logical choice.

You can do a lot if you devote enough time and money to it. The P-40 wing was big, it also had a lot of "stuff" in it. Things like spars and ribs. Spitfire had one big box spar in the front and a little spar in the back used as attachment point for flaps/ailerons. P-40 used several spars in the front and 2-3 in the back. Amount of free space might have been lacking in the earlier versions (the ones with 1-2 small guns in each side) and gotten better with the D/E. But they might have needed another revision to fit the 20mm inside and they didn't want to take the time. Spitfire wing with 20mm was not exactly neat and tidy. Spitfires had at least 4 wing types not including the photo-recon wings.
There are also things you can do at the factory and things you should not try a home (service squadrons) like drilling large holes though the main spar/s.
What you can do at the factories also depends on how desperate you are for new aircraft. Situation desperate you don't try changing things much.
The HS 404 was a very good gun, it was also large and heavy. French fighters were, in general, small.

I particularly dislike the VG. 33. It is small, it is not all that light (2656kg) while using a 468-470kg engine and a so-so armament. I like the HS 404 but a single 60 round drum in the summer of 1940 and four 7.5 machine guns is not really first rate. Summer of 1940 saw a lot of changes or planned changes. Old performance figures in English language books are suspect. Like the 36,000 ceiling. This from a plane with a lower altitude rated engine than a P-40C (by about 760 meters) and a higher wing loading. Of course getting max speed at 5200 meters out of an engine rated at 4000 meters was quite trick to begin with.

The French had used a bit too much wine at lunch when they figured that "wood" was a non-strategic material. Wood in general is not strategic . Wood you can actually make airplanes out of is. Straight grain, knot free spruce is not common in many countries and it turns out that a lot (around 40% ?) of the purchased Spruce for the VG 33 program was not useable. Oops? There is always a large amount of unsuitable wood in large projects. Ask any honest wooden boatbuilder.
Did France have much large virgin spruce forests in France? British had to import the non-strategic spruce and balsa into England to make Mosquitos. If wood is taking the place of food or metals or war materials in convoyed ships does it become a strategic material?
French were far from the only people to think that building high performance wooden aircraft was easy. After all many countries had built thousands of wooden warplanes just over 20 years before
Soviet wooden airplanes are kind of a case in point. Yes they used wood. They also used a crap load of phenol-formaldehyde resin. Were they wood or composite?
The Yak-3 saved about 150kg over the Yak-1 in part because of the smaller wing and in part because in 1943/44 they could replace the wooden(composite?) wing spars with duralumin. Wooden aircraft just about always came out heavier than metal ones when built to the same load factor/s.

 

[Elan Vital]

I particularly dislike the VG. 33. It is small, it is not all that light (2656kg) while using a 468-470kg engine and a so-so armament. I like the HS 404 but a single 60 round drum in the summer of 1940 and four 7.5 machine guns is not really first rate. Summer of 1940 saw a lot of changes or planned changes. Old performance figures in English language books are suspect. Like the 36,000 ceiling. This from a plane with a lower altitude rated engine than a P-40C (by about 760 meters) and a higher wing loading. Of course getting max speed at 5200 meters out of an engine rated at 4000 meters was quite trick to begin with.

The French had used a bit too much wine at lunch when they figured that "wood" was a non-strategic material. Wood in general is not strategic . Wood you can actually make airplanes out of is. Straight grain, knot free spruce is not common in many countries and it turns out that a lot (around 40% ?) of the purchased Spruce for the VG 33 program was not useable. Oops? There is always a large amount of unsuitable wood in large projects. Ask any honest wooden boatbuilder.
Did France have much large virgin spruce forests in France? British had to import the non-strategic spruce and balsa into England to make Mosquitos. If wood is taking the place of food or metals or war materials in convoyed ships does it become a strategic material?
French were far from the only people to think that building high performance wooden aircraft was easy. After all many countries had built thousands of wooden warplanes just over 20 years before
Soviet wooden airplanes are kind of a case in point. Yes they used wood. They also used a crap load of phenol-formaldehyde resin. Were they wood or composite?
The Yak-3 saved about 150kg over the Yak-1 in part because of the smaller wing and in part because in 1943/44 they could replace the wooden(composite?) wing spars with duralumin. Wooden aircraft just about always came out heavier than metal ones when built to the same load factor/s.

The French authorities figured out making good wooden combat aircrafts was not such a no-brainer indeed. They ended up importing the spruce from Canada, which would probably be in competition with the Mosquito. Romanian spruce was also imported but was not suitable for every part.
Ironically, France was not in such a bad place re aluminium as other European countries in spite of the fears of aluminium shortage. The fall of France disrupted British plans as France was meant to provide aluminium products, while Germany's situation was improved with the capture of French stocks and production.

Afaik, some late Arsenal projects before the Fall of France returned to metallic structures only. It is also possible that, down the line and as the situation evolves, that the roughly 50/50 split in production rates of Dewoitine and Arsenal fighters would have been changed in favor of more Dewoitines, if wood is an issue. Another factor is that past the VG-33, the Arsenals to be produced used the same Hispano variants as contemporary Dewoitines, so the use of a less advanced engine was no longer a reason to use different airframes.

The merits of either platform in the long term would have been difficult to assess, since we never got to see that story unfold and good information on the Arsenals, let alone the Dewoitines is scarce. The VG-33 was somewhat less draggy but the aerodynamic improvements meant for the later D-520 series and the D-55X series make both types converge, and the engines and armament are mostly the same.

 

[Steamed_Banana]

The French authorities figured out making good wooden combat aircrafts was not such a no-brainer indeed. They ended up importing the spruce from Canada, which would probably be in competition with the Mosquito. Romanian spruce was also imported but was not suitable for every part.
Ironically, France was not in such a bad place re aluminium as other European countries in spite of the fears of aluminium shortage. The fall of France disrupted British plans as France was meant to provide aluminium products, while Germany's situation was improved with the capture of French stocks and production.

Afaik, some late Arsenal projects before the Fall of France returned to metallic structures only. It is also possible that, down the line and as the situation evolves, that the roughly 50/50 split in production rates of Dewoitine and Arsenal fighters would have been changed in favor of more Dewoitines, if wood is an issue. Another factor is that past the VG-33, the Arsenals to be produced used the same Hispano variants as contemporary Dewoitines, so the use of a less advanced engine was no longer a reason to use different airframes.

The merits of either platform in the long term would have been difficult to assess, since we never got to see that story unfold and good information on the Arsenals, let alone the Dewoitines is scarce. The VG-33 was somewhat less draggy but the aerodynamic improvements meant for the later D-520 series and the D-55X series make both types converge, and the engines and armament are mostly the same.

Dewoitine D.520 did have some combat history after the Battle of France, and seems to have comported itself fairly well against the Allies, including the US Navy and the RAF in 1943, especially for a 1940 design with a very questionable logistics tail in some cases (like in Italian and Bulgarian use).

But in general, I agree we don't know the actual histories or how these two fighters, or the possible MS 540 type, or a possible improved Bloch 155 etc. would have fared. That's why we have a "What-If" section, it's something that can be explored to a limited degree, and perhaps pondered. But we won't have any definitive answers in a discussion here.

The ultimate merits of using wood or not is pretty much irrelevant to me, they could have switched to aluminum alloys, the fact that the VG.30 series was originally conceived as a (mostly) wooden plane just speaks to it's original design intention as being a quick to produce and relatively inexpensive design.

Also, yes the Soviets used phenol resin coatings on a lot of their fighters. So what?

Bottom line is that it's clear to me that the French were actually very advanced in fighter and military aircraft design for 1940, and these existing aircraft design families, as well as those of their best bombers, attack planes and recon planes, clearly included some with potential to be world class. They also had some apparent duds, but so did every country at that point.

 

[bf109xxl]

Soviet wooden airplanes are kind of a case in point. Yes they used wood. They also used a crap load of phenol-formaldehyde resin. Were they wood or composite?
The Yak-3 saved about 150kg over the Yak-1 in part because of the smaller wing and in part because in 1943/44 they could replace the wooden(composite?) wing spars with duralumin. Wooden aircraft just about always came out heavier than metal ones when built to the same load factor/s.

A small addition. Metal wing spars appeared already on the Yak-9 (more precisely, on the Yak-7D/DI) in 1942. The Yak-3 wing was designed similarly to the Yak-9.
The use of metal spars on the La-7 also resulted in a noticeable weight reduction.
By the way, the expansion of the use of metal led to negative effects: in the conditions of the Soviet aircraft industry, the joining of wooden and metal parts was often of poor quality, which led to many accidents and disasters. In particular, Yak-3s suffered from this - after the war they were all quickly written off.

 

[SaparotRob]

And what does this one look like?
View attachment 851232

An LSD flashback. Nice colors, though.

 

[Bretoal2]

Of course getting max speed at 5200 meters out of an engine rated at 4000 meters was quite trick to begin with.

It's (relatively) easy to achieve ram effect with a properly designed air intake—ram effect that substantially increases the actual rated altitude. It's even easier with a wind tunnel that allows you to work at real (1:1) scale. Hispano-Suiza had one, and, what a coincidence, we have a photo of a VG33 family aircraft being tested in this wind tunnel.

And for the record, the "ram effect" is more and more significant as the aircraft's speed increases.

Known examples of ram gain: with a Gnome et Rhône 14N48/49 whose rated altitude on the bench is 3,600 m, LeO 451: maximum speed of 495 km/h at 4,800 m., Bloch 155 520 km/h at 5,200 m., Bloch 174 530 km/h at 5,200 m. That is respectively 1,200 and 1,600 m. higher.

 

[Steamed_Banana]

Top speed is usually a couple of thousand meters above critical altitude for the engine, also, because the air is thinner bruh

 

[Shortround6]

Top speed is usually a couple of thousand meters above critical altitude for the engine, also, because the air is thinner bruh

Perhaps the French should have told everybody else how they did it?
Everybody else seemed to get around 2-3000ft from RAM effect (and the thinner air). And yes fighters do better than most bombers because they are going faster.
Spitfire does a bit better than the Hurricane using the same engine (and the same air intake ?) due to the higher speed. Granted the British intakes do NOT appear to be particularly sophisticated.