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

[TM06]

The whole VG.30 series seems to have stayed with the 14m2 wing?

From what I can find, all of them from VG.30 to VG.39Bis had the 14 m^2 wing with the sole exception of the VG.60 which was planned with a 17 m^2 wing.

Disregarding the Caudron series we do have Dewoitine going to a small wing (13m2 ?) with the 551.

The base D.551's wing was 13 m^2, but the D.553 and D.554 (the ones fitted with the 12Z) were planned to have a 2 m^2 extension of the wing surface for a 15 m^2 wing. However the M.520T was based primarily around the D.551 platform and had little in common with the base D.520, so the 17.3 m^2 wing is a reasonable possibility for the D.55x.

 

[tomo pauk]

but the D.553 and D.554 (the ones fitted with the 12Z) had a 2 m^2 extension of the wing surface for a 15 m^2 wing.

(my bold)
The word "had" might be pushing it.

 

[TM06]

(my bold)
The word "had" might be pushing it.

Were planned to have.
Better?

 

[tomo pauk]

And this is part of the problem for the French fighters. For weight a single 20mm and four 13.2mm guns is about the same as six 12.7mm/.50 cal guns. And the US screwed up the P-40D/E and Wildcat with that weight armament. They also put in more protection than some other nations did. US self sealing tanks were among the best but they were heavy. P-40 and Wildcat also didn't have their engines improve as much as needed in 1942/43 to stay first rank.

The last sentence quoted points to the crux of the matter - having hundreds of HP less at 15000-25000 ft when compared with the best was a far greater concern than having an extra pair of the HMGs installed. Even the small power increase, like what happened with the late 1942 V-1710s, made the performance figures of the P-40s and P-39s much better (if late by at least a year).
BTW - the P-39D was with an even greater firpower weight installed when compared with P-40E, yet it was lighter by about 1000 lb.
The 6-gun F4F was with the folding wing, that added a lot of weight by itself, while the whole Wildcat family was competing with Hurricanes for the title of who can make a draggier fighter - not good for perfomance.

USA (USAAC/AAF in this context) did screw up, but sometimes the airframe companies made a wrong turn, so to say. Sometimes it took the engine companies many precious months to came out with the engines with competitive power at altitude that is coupled with small drag and good/great reliability.
Combine all 3 factors, and the P-40E and P-39D happen.

 

[Shortround6]

From what I can find, all of them from VG.30 to VG.39Bis had the 14 m^2 wing with the sole exception of the VG.60 which was planned with a 17 m^2 wing.

I have spent about 15 minutes just trying to figure out what a VG.60 was. Lots of drawings, You can even buy models.
most or all (?) show/indicate a rather large radiator duct inside the rear fuselage, super P-51 style.
They show eight machine guns in the wing and most claim they are .50 cal'13.2mm. Great! 17m2 wing for the armament of a P-47. Wonder how that works.

Proposed engines are all over the place. Including
1,000 hp Hispano-Suiza 12Y-51 supercharged by a two-stage Sidlowsky-Planiol turbo-charger."
Late war or postwar they talk about a Jumo 213.
Yeah, plane about the size of a 109 with 960kg engine in the nose.
Some drawings show a larger plane than the 1940 version?

There are "what ifs" and there are fantasy planes.

Right now this seems to be leaning well into fantasy.

 

[Shortround6]

the P-39D was with an even greater firpower weight installed when compared with P-40E, yet it was lighter by about 1000 lb.

It may have been closer to 500-600lbs going by "design" weight.
P-40E was "designed" to fly with 120 US gallons. The internal tanks would hold 144.5 gal (pilots manual) and the ammo load was a little strange. 1410 rounds (235 per gun average) but there was room for 1870 rounds (311/2 average). 138lbs just in ammo if they filled the trays/boxes?

To me the killer of the P-40D/E was armament.

plane....................guns................ammo................misc.equip..................total...................with overload
P-40D...................256...................300.........................65.5............................621.5........................1059.5lbs (2460 rounds)
P-40E....................384...................423.........................94................................901............................1039lbs (1810 rounds)
P-40C...................244*.................356**.....................---***..........................600lbs***.................600lbs

* may include some of the misc.equip
** 380rpg of 50.cal/500rpg of .30
*** different charts, does not show misc. equip. but the per gun weight for the .50s is higher than for the P-40D/E

Wing/fuselage was stressed for that load (+ six 20lb bombs) Wing was about 100lbs heavier than a P-40C wing.
The misc. equip for the guns are the remote chargers and firing mechanisms (electric solenoids) and possibly the mounts.

The Army kept up the fiction of the 120 gallon fuel load for quite some time. Normal Gross weights for later normal models at least to the M are for 120 gal. How they were flown in combat is another story.

 

[TM06]

I have spent about 15 minutes just trying to figure out what a VG.60 was. Lots of drawings, You can even buy models.
most or all (?) show/indicate a rather large radiator duct inside the rear fuselage, super P-51 style.
They show eight machine guns in the wing and most claim they are .50 cal'13.2mm. Great! 17m2 wing for the armament of a P-47. Wonder how that works.

Proposed engines are all over the place. Including
1,000 hp Hispano-Suiza 12Y-51 supercharged by a two-stage Sidlowsky-Planiol turbo-charger."
Late war or postwar they talk about a Jumo 213.
Yeah, plane about the size of a 109 with 960kg engine in the nose.
Some drawings show a larger plane than the 1940 version?

There are "what ifs" and there are fantasy planes.

Right now this seems to be leaning well into fantasy.

It's an odd case.
The design was a preliminary sketch started Pre-Fall with the 12Y-51 and was totally abandoned during the occupation, however it was restarted after the Liberation with the Jumo 213E (Most likely an Arsenal 12H?) but was quickly abandoned again once jets became clearly superior to props.
I believe Arsenal used the radiator design from the VG.60 for the VG.70 jet fighter project. As far as I know it was an evolution of the radiator arrangement introduced on the VG.36 but taken up several notches in preparation for the stronger engines.
The amount of guns isn't impossible per say, but I think the designers at Arsenal were getting a bit too excited.
My main point is the expanded wing, showing that Arsenal did plan for larger wings on the VG.30 platform.

 

[Bretoal2]

1,000 hp Hispano-Suiza 12Y-51 supercharged by a two-stage Sidlowsky-Planiol turbo-charger."

They forgot water injection, variable octane fuel and belt driven camshaft with multi-timing.

Many "specialists" don't really know what is an engine....

 

[Shortround6]

The amount of guns isn't impossible per say, but I think the designers at Arsenal were getting a bit too excited.
My main point is the expanded wing, showing that Arsenal did plan for larger wings on the VG.30 platform.

A lot of people, who should have know better, specified too many guns in many planes in 1939-41.
As shown by some of the figures in the post on the P-40s using large numbers of .50cal/13.2mm guns gets really heavy, really quick.
The real problem is the ammo. The .50cal/13.2mm ammo is about 5 times heavier per round than 7.5-7.9/.30cal ammo.
This is also a bit sneaky as this larger .50cal/13.2mm ammo is around 30% heavier than the Italian/Japanese and German 12.7/13mm ammo.
Not only are the projectiles lighter but a British .5in/12.7mm round uses about 60% of the propellent that a US .50 does (or French 13.2mm) and the cartridge case is lighter in proportion. In the US .50 the cartridge case weighed more than the projectile.
A few somebody's had a sever case of brain fade. British were using eight 7.7s so using eight 12.7/13mm isn't that big a change? Even worse in imperial .30 cal vs .50 cal.
Somebody forgot that guns and ammo weights go up with the cube of the caliber.

Now Arsenal seems to have forgotten this. And/or they were fixed on the small wing = low drag.
Curtiss got caught with the P-53/P-60. Originally specified with eight .50s in a 275 sq ft wing (25.5m2) either to compete with the P-47 or army wishes? As the airframe grew heavier and the generation of wonder engines all failed, Curtiss tried to compensate by taking guns out. First down to 6 guns and finally to just 4 guns in a version with an R-2800 engine. They were offering four 20mm guns but the four .50s were to try to get the performance numbers onto the playing field.

The P-40 is interesting in that it went from 1939-40 standards of protection (none) to 1943 standards, also was upgraded in radio equipment (radio includes IFF) in addition changes in armament and in powerplant (minor). Unfortunately the US changed some of it's weight categories and protection (armor and BP glass) was transferred into furnishings and/or armament provisions. Likewise the misc equip under armament just got folded into the weight of the guns, the guns did not actually get 15lbs heavier each.
We in the west do not have detailed weight breakdowns of may non-US aircraft.
P-40 gained about 93lb in armor in the early models. BP glass is separate, Communications (radio, etc) went from 71lbs to over 130lbs in the P-40F and later, Fuel protection went to 80lbs on the P-40B vs the early P-40. Jumped another 160lbs in the P-40C and later but maybe they over did it? and/or the 3 tank set up in the P-40 had a lot of surface area compared to volume of fuel?
P-40C was over 500lbs heavier than a P-40 empty equipped (no ammo or fuel). Gained two .30 guns and the protection, still had early radios. That is about 2lbs per sq ft of wing loading even with the large P-40 wing (21.8m2)

If you want a decent 1942-43 fighter what do you change? Germans and Soviets were stuck with 109 and the Yak's and Lagg/LA, they can't retool in the middle of the war. They limited the armament even as they increased engine power/protection.

 

[Shortround6]

France is a nation that gets swept under the rug when discussing aircraft of WW2, but when looking upon what they had planned, they had a number of strong contenders that likely would have been produced if not for the Fall or if Germany didn't place the embargo on them. Specifically - and the primary aircraft referred to in this discussion - the Dewoitine D.520Z/SE.520Z, Dewoitine D.551, Arsenal VG.39Bis, Bloch M.B.157 and Arsenal VB 10.
These 5 planes were planned to be produced around 1942~1943, meaning their competition would be as such:
Germany: Bf 109 F-4, G-2 and G-6 / Fw 190 A-4 and A-5, A-6, A-7
Britain: Spitfire MK V, MK VIII, Mk IX, LF Mk IX, XVII and XIV / Hawker Typhoon.
Russia: Lagg-3 La-5 and La-5FN / Yak-1, Yak-7B, Yak-9 and Yak-9D and Yak-9T.
USA: P-39D-Q, P-40F. P-40K and P-40N / P-51B and P-51C / P-47C and P-47D /F4F, FM-2/F4U-1 and F4U-1C / F6F-3 and F6F-5.
Italy: C.202EC, C.205 Serie III and C.205N2 / G.55 / Re.2001 and Re.2005.
Japan: A6M2, A6M3, A6M5 / Ki-43, Ki-44 / Ki-61-I and Ki-61-II / N1K1-J and N1K2-J.
So my question to you fine folks is this:
How would these fearsome French fighters fare facing the fierce foes of the early forties?

Simplified the original post some.
Planes in italics are common planes in service in 1942-43 and since 1942-43 does cover 24 months there were some considerable changes made (P-40E to P-51C anyone?)
Planes are lined out saw no service in 1943. Small numbers of types that only a few were made but they were not in operational service. More important in 1944 but that is later than the question.

We could also sort out most of the 1943 aircraft from the 1942 aircraft.

For the French in 1943 a lot depends on the theoretical engine development and/or success at getting American/British engines.

Germany: The French fighters might stand up to the 109s fairly well in 1942, depends on the DB 605 restrictions? Against the 190s things don't look so good.
Britain: French fighters vs the British might go either way against the Spitfire Vs. Might depend on missions/altitudes. Against two stage superchargers it doesn't look good.
Russia: French fighters would stand up well in comparison to the Laggs/Ls-5 or Yaks in 1942. in 1943 more depends on French improvement.
USA: Early/mid 1942 the USA does not shine. later in 1942? by mid/late 1943 the US is far ahead of the French.
Italy: Italy has trouble with the French 1940 fighters in 1941/42. They need the DB 601 engines to beat the 1940 French fighters. 1942 French fighters are probably going to beat the 1942 DB 601 powered Italians. Mid 1943 Italians with DB 605s? Except there are never going to many of them.
Japan: A lot depends on how the French planes are flown and what improvements (armor, protected tanks, etc) they have had. If the French try to dog fight they are screwed and nothing to do with the capabilities of the planes. The A6M5, Ki-44 and Ki-61 are pretty much mid 1943 and later.

This is very short summary and lot depends on how fast H-S sorts out the 12Y-51 engine, 1000hp at 3260 meters is a useful increase over 910hp at 5250meters the -49 had but obviously it does nothing for altitude performance. Getting the 12Z into production and in what form/s is very important.
By mid war the 12Z seems to have been good for around 1300hp at 4000-4250meters? A bit more low down depending on fuel.

The G-R 14R engine to me, right now, is a big unknown. Needs more research. It might have been a decent 1300-1400hp engine at medium altitudes in 1942/43. Some of the post war numbers look rather optimistic.

 

[Shortround6]

To expand on the above a little bit I will address the armament issue/s.
I am assuming the French Hispano powered aircraft are using a single 20mm gun with around 120 rounds in a belt feed. They had about 18 months to get it into production and service by 1942 and since the British did it in less time with drawings 'borrowed' during Fall of France and spent a number of months trying to fix something that didn't need to fixed I don't see a problem with the belt feed.
I am assuming the French fit 4-6 7.5mm machine guns in the wings for the Hispano powered fighters. This sorts out as follows. It also assumes that a single H-S 20mm cannon has about the same firepower as 10 rifle caliber machine guns. Differences for other guns noted below.

Germany: VS the 109F-4 and Early Gs. The H-S 404 has about equal firepower to the MG 151/20. The German pair of 7.9mm guns is rather lacking. Something that will become all to common is trying to compare cowl guns with wing mounted guns. Cowl guns have less actual fire power (per second) than wing mounted guns because of the lower rate of fire due to synchronization. At least 10% and sometimes 30% (or more). The small machineguns were less affected than the larger guns. With the 109G-5/6 and the pair of 13mm guns things get better for the Germans but maybe only bring them up to equaling four of the French 7.5s. The German MG 131 is the least powerful 'heavy' machine gun and while the Germans resorted to electrical priming to help solve the synchronization problem the gun still fired at least 10% slower than a non-sychro gun. French were specifying large quantities of 7.5 ammo but they may have cut back on that with more war experience. Germans did mount 20mm guns under the wings but that only lasted for a short period of time as general issue before going to bomber busting only (allied planes were getting better faster than the Germans?). The FW 190A-2 started the two 20mm MG 151/20 and this is a problem for the French, and just about everybody else. The 190 was fast and it carried a lot of ammo, except for the 20mm MG/FFs in the outer wings which may have not been such a good idea? At any rate the wing root mounted 20mm guns, while being electrically primed to aid synchronization did loose some of the rate of fire. The 190 didn't change armament until the end of 1943 except for deletions of the outer wing 20mm MG/FFs for various reasons.

Britain: Spitfires had gone over to belt fed HS 404s by the beginning of 1942 so any belt fed Vbs were soon to be retired/rebuilt. The four .303 in the wing were pretty much equal to the four 7.5mm French guns, The MAC 1934s may have fired a little faster but used a slightly lighter bullet. French planes could hold a lot more ammo. Typhoons were mostly four 20mm guns and were pretty much world leaders in armament. Same could not be said for the Sabre engine.

Russia: Soviets are fighting to hang on here. The 20mm ShVAK cannon was about 85% as effective as the Hispano. It fired a bit faster but since most Soviet fighters only carried about 120 rounds of cannon ammo, it ran out a bit quicker. The saving grace was the 12.7mm UB machine gun. This, when synchronized, was about 4 times as effective as the MAC 1934 7.5mm machine gun in the wing. Now if we want to try to compare a French fighter with six MAC 1934s in the wing and factor in the higher effectiveness of the HS cannon things get very close to the 'standard' Soviet one 20mm and two 12.7mm guns. But the Soviets run out of ammo for the 12.7mm guns if they stay in combat very long. Most Soviet fighters carried a max load of 220 round for their 12.7mm guns and that was worth 16-17 seconds of firing time.

USA: Both complicated and simple, aside from the P-39 and P-38 (not included here) the USA had standardized on the M-2 .50 cal gun for everything else. In 1942, again except for the P-39 the synchronized guns had gone away (ok, A-36s aside) and the differences were 4 guns, 6 guns or eight guns, all in the wings and different amounts of ammo. One 20mm HS was worth about 3 .50 M-2s and one M-2 was worth about 3 MAC 1934s so..........................as long as the 20mm was firing a French fighter with 6 MAC 1934s pretty darn close to a six gun American fighter. M-2 still needed some sorting out in 1942 with the feed systems in the wings.

Italy: Things don't look good for the Italians, Without the German MG 151s they are depending on the Breda 12.7mm guns and cartridge is low powered, 1/6th to 1/7th as powerful as the Hispano and when synchronized, as most Italian fighters using them, they fired slowly. They are just under twice as effective as a single MAC 1934. They did carry a lot of ammo for 12.7-13mm guns. The 2nd strike is that the 7.7mm Breda was also slow firing, about 3/4s as fast as the MAC 1934 at best, 1/2 as fast at worst. So two 12.7mm guns in the cowl and a single 7.7 in each wing doesn't look good. They NEED that 20mm MG 151 in each wing.

Japan: The cowl mounted 7.7mm guns are about 2/3rds as good as the MAC 1934 at best. The Army 12.7mm Ho-103 gun fires faster than the Italian gun but also suffers from synchronization. Japanese Army may need three 12.7mm to equal six MAC 1934s? Short barreled type 99 20mm cannon are about 1/2 as powerful as the HS 404 and with 55-60 round drums? Larger magazines in the A6M3 help. The long barrel Type 99 is about 60% as powerful as the HS 404.

That is basics, some guns offer a bit more help to the pilot in area of less time to target making deflection shooting easier or having all guns need the same lead/defelction at reasonable shooting distances.

French, had they adopted the Belgian 13.2mm gun, could have swapped them in for one 13.2mm gun for three MAC 1934s without much trouble and adjusted ammo accordingly.
The 13.2mm gun may have had 4 times or a bit more firepower than the MAC 1934. Installing two in each wing may have been possible for an increase in weight of around 140kg (including 250rpg) over the weight of 1 gun each side. May depend on the actual amount of 7.5mm being replaced. Roughly 1250 rounds of 7.5mm ammo equals 250 rounds of 13.2mm ammo?

A M.B. 157 with two HS 404 with belt feeds and four 7.5mm guns (roughly the same as a Spitfire Vc or IX) is about as good as it gets (Typhoon aside) in 1942-43.
FW 190 is better for about 6-7 seconds and then the MG/FFs are silent.

Edit, I am using the numbers for the British HS 404 cannon. The French version was supposed to fire faster, British had slowed theirs down for better reliability. Sped them back up with MK V with mechanical changes.

That is pretty much it for fighter to fighter or fighter vs bomber.

 

[TM06]

-snip-

An actual answer to the original question! Huzzah!
So to make it short, France has a highly competitive armament package for their main fighters with the only explicitly better packages at the time being on the Fw 190 and Hawker Typhoon IB? And along with that, the fighters are quite competitive or even superior against a majority of opponents they'd be facing from other nations?
That's quite a strong showing from them overall, and given that the other French projects of note (LeO 455, Br 482, M.B.162, Amiot 357, Br 697/Br 700, LN.42) aren't part of this discussion, it leaves some interesting implications for the abilities of those aircraft as well.

 

[bf109xxl]

Russia: Soviets are fighting to hang on here. The 20mm ShVAK cannon was about 85% as effective as the Hispano. It fired a bit faster but since most Soviet fighters only carried about 120 rounds of cannon ammo, it ran out a bit quicker. The saving grace was the 12.7mm UB machine gun.

According to the recollections of Soviet fighter pilots, they very rarely exhausted all of their ammunition. They considered the ammunition of a Soviets fighter (Yak, LagG/La) to be quite sufficient. I wrote about it earlier, but you repeat the erroneous thesis about insufficiency of the ammunition of Soviet fighters again.

 

[Shortround6]

According to the recollections of Soviet fighter pilots, they very rarely exhausted all of their ammunition. They considered the ammunition of a Soviets fighter (Yak, LagG/La) to be quite sufficient. I wrote about it earlier, but you repeat the erroneous thesis about insufficiency of the ammunition of Soviet fighters again.

And I will keep repeating the this "erroneous thesis".

Because it is true that the Soviet aircraft, in general carried less ammo. That is true, it is not erroneous unless 120 is somehow greater than 140 or 150.

The flip side is if the soviet fighters could perform their missions, for the most part, with the existing ammo under the conditions/missions they were flying.
Which is a different question/problem.

When we are comparing aircraft from different nations that flew under different conditions it helps to understand the limitations.
For instance US fighters flew with anywhere from 200-201 rounds per .50 cal gun to 425-430 rounds per gun. Now were they flying with too much ammo and hurting performance (30 seconds of firing time roughly) and they should have all used 200-240rpg or were the planes with 200-240rpg running out an times and not able to complete missions?
Might depend on who (which pilots) you talk to, when (what year or even month) and in which theater and/or base (land or carrier).

A Soviet fighter with a 20mm ShVAK cannon often carried 120rpg, Which at it's nominal rate of fire of 800rpm is 13.333rps. Using 13rps because I am being lazy that means a firing time of 9.3 seconds. Which may very well have lasted most soviet pilots through the combats they were engaged in. It is certainly better than the firing time of the Spitfire Vb, The 109E and the early Zeros and all of the French fighters of 1940 by around 50%.

Now a lot of militaries often pushed pushed things to extremes, just in case. And some times the extremes actually hurt the performance in the field. P-40 is a classic example, went from 370lbs of guns/ammo to 600lbs and on the P-40E to 901lbs without changing the engine much. Some field modifications, and some P-40Ls and first P-40Ns dropped the armament weight back to about 600lbs to try to get performance back. Firing time of these planes were about 15.4 seconds. Vast bulk of the P-40s went back to six guns with more ammo. What the Soviets did with them I don't know. I also strongly suspect that when carrying large bombs under the wings (2 or 3 total) the P-40s were not carrying full ammo.

Getting back to the Soviet fighters, the 20mm ammo ran out after about already mentioned 9.3 seconds (or perhaps a few tenths more) but the 12.7mm UB machineguns lasted longer. Synchronized 12.7mm UB machine guns are often credited with 900rpm or 15rps. It seems in western books the UB guns most often had around 220rpg for a firing time of 14.7-15 seconds. A few planes had as little as 170rpg (11.4-12 seconds) and some has 250rpg and The Mig-3 had 300rpg for 20 seconds?
This mismatch between cannon firing time and machine gun firing time was very common.

Now for the Soviets, are the pilots say if they didn't run out of cannon ammo or just ammo in general? For most Soviet pilots they had about a 5-6 warning time between the cannon running out and the 12.7mm guns running out.

I will note that the LA-5 went to 200rpg and since the gun fired slower ( I don't know by how much) the LA-5 pilots had at least 60% more 20mm firing time than the Lagg-3 and Yak pilots had. Late La-7s got three guns and 170rpg.

The Soviets may have been happy with the ammo carried and the firing times they got. Other nations may not have been. Wither that was based on combat results or theory is subject to question.

US P-39 was another example of over specifying. They took two .30 cal guns with 500rpg out of the nose and then stuck four .30 cal guns with 1000rpg in the wings. Increase in ammo weight alone was over 180lbs and the need to keep the .30 cal guns running for 50 seconds after the cannon and cowl .50s had run out of ammo around 30 seconds earlier? In service the loading chart often stated just 300rpg (15 seconds of firing time).

I don't know what the 'magic' time was. US Navy wanted a lot of firing time. Doesn't mean they were right for land based fighters flying 1-2 hour missions.
And the flip of that Planes with the firing duration of Soviet fighters might have been a handicap in carrier battles, as shown by the Japanese at Midway. Granted the Japanese Zeros had a shorter firing time than the Soviet planes but the Japanese were working to increase the firing time substantially either during the battle or just after. And then they increase the firing time about 25% over the new longer time.

 

[bf109xxl]

And I will keep repeainting the this "erroneous thesis".

For no good reason.

Because it is true that the Soviet aircraft, in general carried less ammo. That is true, it is not erroneous unless 120 is somehow greater than 140 or 150.

"Less" is not equal "insufficient".

The flip side is if the soviet fighters could perform their missions, for the most part, with the existing ammo under the conditions/missions they were flying.
Which is a different question/problem.

Nope. This is exactly the same question: how much ammunition is appropriate for particular air combat conditions?

When we are comparing aircraft from different nations that flew under different conditions it helps to understand the limitations.

Of course. But there is a good reason to assume that the conditions of air combat in a confrontation between the hypothetical French fighters and the Germans would be similar, if not exactly the same, as on the Eastern Front. As a consequence, the French fighters would be quite sufficient with less ammunition, and they could be lighter, i.e. the engine power demands could be somewhat reduced.

 

[Shortround6]

Of course. But there is a good reason to assume that the conditions of air combat in a confrontation between the hypothetical French fighters and the Germans would be similar, if not exactly the same, as on the Eastern Front. As a consequence, the French fighters would be quite sufficient with less ammunition, and they could be lighter, i.e. the engine power demands could be somewhat reduced

In 1940 that was not the way the French were leaning. Of course being knocked out of the war in 1940 they didn't have much chance to change their minds. They were specifying ridiculous amounts of 7.5mm ammo, more in line with the P-39 and Beaufighter wing guns. I fully agree that the French could have scaled back some of their ammo requirements to benefit of performance.

I do not agree that the French front would have evolved to a repeat of the Soviet front in regards to air combat. While the altitudes for air combat stayed at mid and low level for the phony war and a lot of the May thru June fighting was at low level that is not the way the French wanted the war to go. They wanted to bomb Germany, They wanted to keep the Germans from bombing France (Cities, industry, etc).
Perhaps France would be kept on their back foot and not be able to develop an air offensive while keeping the defense.
Perhaps the Germans would be content with an offensive tactical air operation and not try to bomb French industry and be forced into the altitudes than prevailed during the BoB?

They don't need P-51s but they need fighters with more range/endurance some of the Soviet fighters had. They also needed better altitude capability. In part because they not only wanted to bomb at higher altitudes but because the Germans were going to want to bomb at higher altitudes and/or bomb at night.
French were rather late getting AA guns into production. Would this continue? Would they be able to buy AA guns?
A higher density of AA guns will force air combat higher.
Will France deploy radar in 1941-42?

The French high command had fallen for the same bomber centric thinking that British had (and the Italians) and would probably had tried to pull it off if they could supply enough fighters to defend France. French thinking was pretty bad in 1939/40.

But even forgetting Berlin the French were going to need at least some fighters that could stay in air for 2-3 hours and do it at 15-25,000ft. (escort to Nuremberg or Bremen ?)
Or stop the Germans from getting 100 or miles past Paris or to the south.

The fighting in France is going to be in a higher density area than Russia. With better (French phone system aside) communications. Both sides may resort to large commitments to land battles at certain points but use a lot of the bombers for strategic use during lulls in the land battles ( we are talking about 2-3 years here?)

And we are back to quality over quantity or the other way around. A lot of adequately (?) armed fighters or bit fewer well armed fighters?

 

[TM06]

In 1940 that was not the way the French were leaning. Of course being knocked out of the war in 1940 they didn't have much chance to change their minds. They were specifying ridiculous amounts of 7.5mm ammo, more in line with the P-39 and Beaufighter wing guns. I fully agree that the French could have scaled back some of their ammo requirements to benefit of performance.

I do not agree that the French front would have evolved to a repeat of the Soviet front in regards to air combat. While the altitudes for air combat stayed at mid and low level for the phony war and a lot of the May thru June fighting was at low level that is not the way the French wanted the war to go. They wanted to bomb Germany, They wanted to keep the Germans from bombing France (Cities, industry, etc).
Perhaps France would be kept on their back foot and not be able to develop an air offensive while keeping the defense.
Perhaps the Germans would be content with an offensive tactical air operation and not try to bomb French industry and be forced into the altitudes than prevailed during the BoB?

They don't need P-51s but they need fighters with more range/endurance some of the Soviet fighters had. They also needed better altitude capability. In part because they not only wanted to bomb at higher altitudes but because the Germans were going to want to bomb at higher altitudes and/or bomb at night.
French were rather late getting AA guns into production. Would this continue? Would they be able to buy AA guns?
A higher density of AA guns will force air combat higher.
Will France deploy radar in 1941-42?

The French high command had fallen for the same bomber centric thinking that British had (and the Italians) and would probably had tried to pull it off if they could supply enough fighters to defend France. French thinking was pretty bad in 1939/40.

But even forgetting Berlin the French were going to need at least some fighters that could stay in air for 2-3 hours and do it at 15-25,000ft. (escort to Nuremberg or Bremen ?)
Or stop the Germans from getting 100 or miles past Paris or to the south.

The fighting in France is going to be in a higher density area than Russia. With better (French phone system aside) communications. Both sides may resort to large commitments to land battles at certain points but use a lot of the bombers for strategic use during lulls in the land battles ( we are talking about 2-3 years here?)

And we are back to quality over quantity or the other way around. A lot of adequately (?) armed fighters or bit fewer well armed fighters

If I may go into speculation zone here, the 3 main fighter aircraft they had planned seem to fit into those niches quite nicely.
- The base D.520 had better range than the Spitfire and Bf 109, and given that they maintained those wing fuel tanks on the SE.520Z that allowed for that increased range, the SE.520Z would likely take up that mantle of Escort Fighter. The mediocre high altitude performance is a problem, but the S-P supercharger was a step in the right direction, and two-stage superchargers seem to be on the cards looking at the Spanish 12Z development.
- The M.B.157 is a shoe-in for the Interceptor role; it had the heaviest armament package of the three with the biggest room for growth along with excellent high-altitude performance owing to its stellar supercharger. Perhaps by late 1943 it'd swap to a quad cannon loadout?
- The VG.39Bis had good high-altitude performance but its small wing profile would seriously harm its chances above 6,000 m. However its light weight and good manoeuvrability would likely make for a potent Point-Defence Fighter - stationed at airfields near critical industry to deal with threats below 6,000 m.

I'm unsure where the D.55x would fall in the mix. The D.551 could likely get by as a pure fighter around late 1940 to 1941 until they get the 12Z up and running, at which point it would evolve into the D.554 or M.520T (either or, they're pretty similar). A pure fighter is perfectly fine, and if the blanket statement of France being pushed back 4~5 years in overall development is true, perhaps the design could evolve to handle either a beefed up 12Z or the 12B around 1944.
A theoretical D.554Bis with a 1,850 hp 12B, 17.2 m^2 wing and a triple cannon loadout would be a monster in combat, with performance comparable with the best of the best.