Advanced French Fighters vs 1942/1943 contemporaries (1 Viewer)

TM06 said:

Rather than being a matter of could have, it's a matter of was going to

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The questions become when and in what quantity. Like I pointed out, the Germans had tanks with the 50m/L42 being built in July.
Nobody changes over instantly. There is always (almost) a period where things a sorted out and production increases.
Germans started working on the 50mm PAK 38 (the L60 gun) in 1938. Troops got them in April 1941. That is the towed gun.

France could have a lot of prototypes being worked on in the Spring of 1940. When were they actually going to show up and what would they be facing?
"First 80 Somua S40 tanks (No.531 to No 610) were supposed to be equipped with this new turret by December 1940, but this never happened for obvious reasons."

Not the German tanks of April 1940.
The Germans had their own coulda/shoulda weapons.
British had their own coulda/shoulda weapons. The 6pdr AT gun drawings were completed in 1939 (?) but the need for weapons in 1939-40 each and every week delayed changing over the factories.
Heck the British had number of coulda/shoulda weapons or choices. The 2pdr AT gun could have been improved by 17-23% by changing the type of projectile, not using tungsten but by using a type of AP round used in naval shells in WW I. British stuck with the cheap AP shot until 1943. British crippled a lot their guns by using using cheap projectiles, not just the 2pdr.

Shortround6 said:

The questions become when and in what quantity. Like I pointed out, the Germans had tanks with the 50m/L42 being built in July.
Nobody changes over instantly. There is always (almost) a period where things a sorted out and production increases.
Germans started working on the 50mm PAK 38 (the L60 gun) in 1938. Troops got them in April 1941. That is the towed gun.

France could have a lot of prototypes being worked on in the Spring of 1940. When were they actually going to show up and what would they be facing?
"First 80 Somua S40 tanks (No.531 to No 610) were supposed to be equipped with this new turret by December 1940, but this never happened for obvious reasons."

Not the German tanks of April 1940.
The Germans had their own coulda/shoulda weapons.
British had their own coulda/shoulda weapons. The 6pdr AT gun drawings were completed in 1939 (?) but the need for weapons in 1939-40 each and every week delayed changing over the factories.
Heck the British had number of coulda/shoulda weapons or choices. The 2pdr AT gun could have been improved by 17-23% by changing the type of projectile, not using tungsten but by using a type of AP round used in naval shells in WW I. British stuck with the cheap AP shot until 1943. British crippled a lot their guns by using using cheap projectiles, not just the 2pdr.

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Eh, hindsight's 20/20. What seems obvious now might not have been obvious then.
Anyways, the S.40 would be facing more-or-less the same opponents until it was to be replaced by the G1. It would definitely start to struggle mid 1941 though, as that's around when the longer KwK 39 L/60 was being put on the Panzer III J1 and when the KwK 40 was put on the Panzer IV F.
The KwK 40 could punch right through the S.40's armour out to 2 km, but the SA 37 could do the same to the Panzer IV F2 out to the same range. The KwK 39 would have trouble though, it could only penetrate the S.40 from half the distance and needs to hit a flat plate to do it. The previous Panzer IV calculation also applies to the Panzer III since they had the same armour thickness at this point in time.
So the S.40 squares up quite well versus the main two German mediums around this period. And if it can fare well versus them, it'll probably do well against the early T-34's, the British Cruisers, the Italian mediums and the American Stuart and Lee.
It would definitely have a hard time against the Matilda II, Churchill and KV-1 however, those have strong enough armour to thwart the SA 37 at most reasonable ranges. The Mk VII Cavalier would also be able to deal with it handily.
Of course this is all in a vacuum without all of the isms. But the S.40 would still be a capable tank from 1940 to 1941.

In English language sources the S.40 history (proposals) is a confused mess.
No agreement on two man turret or still single man or when it was supposed to change, First 40 (?)tanks were supposed to the same turret as the S.35 and production shifting the newer, welded turret at that point. Not sure if there was a 3rd turret.
No agreement as to if the SA 37 gun was to fitted, or when?
Fitting a 220-230hp engine (even diesel) in a 20 ton tank isn't even keeping up.

The SA 37 gun was not quite the powerhouse it is made out.
Adapting it to tank use was possible but perhaps not as easy as some people think.


There is more than just a longer barrel.

The 3 different 47mm cartridge cases. Finding room in the tank for storage is rather easy, 118 rounds of SA 35 can be reduced to 60-80 rounds without much trouble.
Getting the longer round into the breech when reloading is a somewhat harder. Like that thing were the British welded a box on to the back of the Firefly turret to make room for the radio so they could both reload the gun and have room for it to recoil.

There are at least 3 basic things that govern armor penetration of kinetic energy projectiles. One is mass, two is the veleocity (squared) which gives us the energy. And the 3rd is the size hole you are trying to make. Applying the same energy to a hole 20% bigger in diameter doesn't work well.
Then we can argue about type of steel, heat treat, type of point, and so on.

The French gun/ammo was just about equal (maybe a few percent better at close range?) to the German 50mm/60. The German projectile was about 19% heavier but was fired about 6% slower. It was trying to punch a hole about 13% bigger in area. Once you get much past the muzzle than shape of the projectile starts come into play but that doesn't really show up in the first few hundred meters.

French might very well have come up with sub-caliber projectiles in 1941-42. They were experimenting with them before the war.
Some sources may be showing bias one way or another. The British 2pdr was a bit of an odd ball using a much heavier projectile than most 37mm guns and thus giving better performance than most most 37mm guns of near equal velocity. Standard French short 37mm was a popgun. Which is natural considering it dates from 1916 as an infantry support gun that was meant to be carried by several men through the Western front landscape. Not using a 10 ton tank with an 82hp engine to carry a somewhat more potent weapon needs a better explanation than common ammo with the infantry?

Getting a bit more back on track, There were a lot of skilled/smart French designers and engineers. A lot of times they were doing what they were told/instructed. If customer says they want an 1800kg fighter you can either try to build an 1800kg fighter or you can try to build a different aircraft (twin engine bomber or recon machine or????).

French High command had a lot of not very good ideas/doctrines. They went with a lot of different from the main stream ideas in Naval warfare, land warfare and air warfare. some times they worked, some times they didn't. The French often tried to push further against the boundaries than other nations did. And because something can be made to work doesn't always mean it was a good use of resources. The French sometimes going further along a path until they reach the point of illogical conclusion.
The French "75" is something of an example of this. It was not just a good weapon when it came out, it was truly revolutionary. This created several problems for the French. One was they that they were so smart that nobody else could figure out how it was done and duplicate it, ( it did take a few years) but since all it was is a hydropneumatic spring with very careful fitting and assembly that called for some self-deception. The next problem and bigger, was that they thought the "75" would make most other types/calibers of artillery obsolete or redundant and that massed fire from French "75"s could overcome most obstacles and problems. Let's remember that around 1900 field artillery didn't use HE ammo. It used Shrapnel. Shell casings filled with lots of small balls like a shotgun. Devastating against in troops in the open at close ranges (under 2000yds), not so good against trenches, dug outs, fortifications or even troops hiding in ditches. With better High Explosives being made (black powder makes a lousy small HE shell) HE shells did crop up in most world armies. But often only in 10-20% of the ammo stocks. Most other armies also kept (actually made new) Field howitzers to deal with targets (behind hills/buildings) that the field guns could not deal with. French did not build new (or very, very, very few) and the French also neglected medium artillery with their enthusiasm for the "75".
There was nothing wrong and a lot right with the "75" as a gun from 1897 until about 1912-14 compared to many other nations 3in-75-77mm field guns. The Problems showed up in war with the neglect in the areas of complementary guns/howitzers, HE shells, and indirect fire doctrine, tactics, communications.

The French were trying to play world power and they often did not have the financial power or the industrial power to back it up. For many years they were #2 compared to Britain/and empire, which isn't bad but if they want to be #1 and do it on the cheap, things often don't end well. France fell behind Germany in industrialization in the 1800s. By the 1930s maybe they could have stayed even in many ways, but only with good planning. But some of the basic infrastructure was lagging behind. Having two major engine companies was a problem. Splitting up production 3 ways may have also been a problem but neither French company was advancing engine design as fast as they needed to. You can make it through 1940-41 but things get more difficult after that.

Shortround6 said:

If customer says they want an 1800kg fighter you can either try to build an 1800kg fighter or you can try to build a different aircraft (twin engine bomber or recon machine or????).

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You might be onto something there. Take those small light fighters and turn them into reconnaissance aircraft who can defend themselves if needed, or potentially as trainer aircraft. The lack of armour doesn't affect them nearly as much in those roles and you could ditch most of the guns - replacing them with fuel tanks and recon equipment. The R.30 in particular might be a really good trainer due to the aforementioned similarities between it and the Blochs.
The Caudron might finally be useful if it was put in the recon role, since it had very good visibility.

TM06 said:

You might be onto something there. Take those small light fighters and turn them into reconnaissance aircraft who can defend themselves if needed, or potentially as trainer aircraft. The lack of armour doesn't affect them nearly as much in those roles and you could ditch most of the guns - replacing them with fuel tanks and recon equipment. The R.30 in particular might be a really good trainer due to the aforementioned similarities between it and the Blochs.
The Caudron might finally be useful if it was put in the recon role, since it had very good visibility.

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What I meant was that as a designer or aircraft company you have to design/build what the customer (French Air force in this case) wants or think they want. If the designer or aircraft company offers up a design that is what the designer thinks they need but it doesn't line up with the specification or what the Air Force thinks they need (and they could well be wrong) the Air Force either won't order it or needs to have an epiphany.
Designer/company may just shake their head/s, give up on that specification/requirement and propose a submission to a different requirement in order to get business.

The light fighters make lousy trainers. They are harder to fly (higher stalling speed) than most 1938-40 fighters. They are also not cheap enough. Many air forces just used old Fighters as advanced trainers. They were already paid for even if expensive to run.

France had a rather unique view of recon aircraft. This dates from WW I and the French drawing rather different conclusions from everybody else. At times during WW I and at times during the 20s and 30s recon was considered to be the most important function of the air force. More important than fighters to defend France, more important than bombers to attack an enemy country (usually Germany) and more important than tactical bombers to help the army. Knowing what the enemy was doing and where/when it was moving was THE most important thing. In French fashion they flipped/flopped several times on this so a coherent long lasting policy was difficult to follow. This is intermingled with the French fascination with multi seat aircraft for many roles. Multi means multi, it only means two seat when they couldn't figure out how to make a plane with 3 seats given the engines of the time. Or sometimes 4 seat.

This is why they had competing designs for 3 seat aircraft with two 500-700hp engines for recon. They (the Air Force, not the aircraft designers) were convinced they needed a dedicated observer who was not distracted by flying the plane or even watching out for enemy aircraft and using a reward facing machine gun. The 2nd engine was also supposed to help get crippled planes back to base. It was sometimes a bonus if they could replace the observer with bombs and do a little light bombing.
Turning that thinking around to using small fighters in just a few years is going to be hard. They were not looking for photo-recon although they may have wanted photos. They wanted reports by radio and/or artillery spotting duties.
Other countries used single engine planes, some used two seaters and a few (including the US, used 3 seaters)

Single 975-1060hp engine depending on version. US built over 250 of them and then ordered just over 200 Curtiss O-52s in 1940

2 man crew, 600hp engine, Replaced by the Piper Cub
Germans went from the Hs 126 to the Storch and the FW 189.


Inter war French policy/doctrine was different than just about anybody else and they changed priorities several times. At one point they briefly wanted a strategic bombing air force and any fighters and recon aircraft were a diversion of resources from that goal. Then they changed their minds (or changed minister/s) again.

Shortround6 said:

What I meant was that as a designer or aircraft company you have to design/build what the customer (French Air force in this case) wants or think they want. If the designer or aircraft company offers up a design that is what the designer thinks they need but it doesn't line up with the specification or what the Air Force thinks they need (and they could well be wrong) the Air Force either won't order it or needs to have an epiphany.
Designer/company may just shake their head/s, give up on that specification/requirement and propose a submission to a different requirement in order to get business.

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No I got what you meant, it just planted an interesting idea in my head as a potential use for those hopeless light fighters.
Something like "Well those aircraft won't do us very good as fighters, but they may be able to function well as recon!"
Gotta make do with what you have, right?

Going back a few notions, I think the 14R wouldn't have nearly as many growing pains as the 12Z.
Let's take the similar BMW 801 as an example. The major issue plaguing the 801's development was high altitude performance - something about a poor supercharger and lack of resources for high-quality turbocharger designs. The 14R absolutely wouldn't have this problem, as its supercharger was reportedly excellent.
I think the biggest development struggle would be fuel injection, as the 14R used carburettors. However it's not too difficult, as noted by the many engines (radials included) that were changed to use fuel injection. Looking at those engines before and after they received fuel injection could give an insight into how the 14R would perform with its own fuel injection.
- The 12Z went from 1,000 hp in its basic prototype form to 1,400 hp in the 12ZTer (400 hp increase)
- The Merlin went from 1,760 hp in the Merlin 66 to 2,060 hp in the Merlin 130 (400 hp increase)
- The ASh-82 went from 1,700 hp in the M-82F to 1,850 hp in the M-82FN (150 hp increase)
- The Kinsei went from 1,200 hp in the Kinsei 52 to 1,350 hp in the Kinsei 62 (150 hp increase)
- The Kasei went from 1,460 hp in the Kasei 11 to 1,820 in the Kasei 23 (360 hp increase)
Through these examples, we can see that fuel injection can increase the engine's output by anywhere from 150 hp to 400 hp. If we assume the 1,600 hp 14R would have a similar increase, that would allow it to make 1,750~2,000 hp with fuel injection. This figure is roughly consistent with the later BMW 801's - the 14R's closest analogue.
2,000 HP in an M.B.157 would be monstrous.

TM06 said:

Let's take the similar BMW 801 as an example. The major issue plaguing the 801's development was high altitude performance - something about a poor supercharger and lack of resources for high-quality turbocharger designs. The 14R absolutely wouldn't have this problem, as its supercharger was reportedly excellent.

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The S/C on the 14R was indeed one step ahead of what the BMW 801A,C and D had.
Another problem the 801 had was it's weight, and the reliability issues until the fixes were found.

TM06 said:

I think the biggest development struggle would be fuel injection, as the 14R used carburettors. However it's not too difficult, as noted by the many engines (radials included) that were changed to use fuel injection. Looking at those engines before and after they received fuel injection could give an insight into how the 14R would perform with its own fuel injection.

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TM06 said:

Through these examples, we can see that fuel injection can increase the engine's output by anywhere from 150 hp to 400 hp. If we assume the 1,600 hp 14R would have a similar increase, that would allow it to make 1,750~2,000 hp with fuel injection. This figure is roughly consistent with the later BMW 801's - the 14R's closest analogue.

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Let's not get carried away Please see the Calum Douglas' videos about carbs vs. fuel injection - the gain was ~10%.

TM06 said:

- The 12Z went from 1,000 hp in its basic prototype form to 1,400 hp in the 12ZTer (400 hp increase)
- The Merlin went from 1,760 hp in the Merlin 66 to 2,060 hp in the Merlin 130 (400 hp increase)
- The ASh-82 went from 1,700 hp in the M-82F to 1,850 hp in the M-82FN (150 hp increase)
- The Kinsei went from 1,200 hp in the Kinsei 52 to 1,350 hp in the Kinsei 62 (150 hp increase)
- The Kasei went from 1,460 hp in the Kasei 11 to 1,820 in the Kasei 23 (360 hp increase)

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Please, double check the reasons why the engine power figures grew for the listed engines.
Main drive to the power increase was the increase of boost - on the Allied side due to the ever-greater performance rating of the fuel, and on the Axis side due to the usage of the water-alc injection. Americans used both the increased PN fuel and w-alc injection, and sometimes the Germans.
Merlin never gained the direct fuel injection.

tomo pauk said:

Let's not get carried away Please see the Calum Douglas' videos about carbs vs. fuel injection - the gain was ~10%.

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If the gain was only 10%, that would still mean 160 extra horsepower for the 14R which was within my calculations.

tomo pauk said:

Please, double check the reasons why the engine power figures grew for the listed engines.

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I couldn't exactly find much in the way of reasoning, almost everything I could find for the selected engines was "fuel injection boosted power to X". But I also don't have access to all possible sources. If you can offer any, it'd be appreciated.

TM06 said:

I couldn't exactly find much in the way of reasoning, almost everything I could find for the selected engines was "fuel injection boosted power to X". But I also don't have access to all possible sources. If you can offer any, it'd be appreciated.

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The two Japanese engines did not get fuel injection.
They got water/alcohol injection. They had carbs and the water/alcohol was sprayed/injected into the supercharger intake to cool in the intake charge and cool the engine.
P-47s used water/alcohol in several stages and in the last got 2560-2600hp from the normal 2000hp engine BUT they were also using a turbo charger to provide a large amount of extra boost. The Navy engines with mechanical superchargers and water/alcohol were limited to several hundred HP lower than the P-47s.
Merlins operating anywhere near 2000hp were using 100-150 or 115/145 fuel and 20-25lbs of boost.
The Soviet M-82 engine got not only fuel injection, they got increased supercharging (different gears or larger blower?), increased finning on the cylinder head (better cooling), valves changed, pistons strengthened and supercharger modified. Russian accounts are sometimes not really forthcoming with actual details. There may also be a question as to rpm used?
The M-82FN gained 88kg over the M-82F and it wasn't just the weight of the fuel injection system.

TM06 said:

If the gain was only 10%, that would still mean 160 extra horsepower for the 14R which was within my calculations.

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Fuel injection alone may not do much. Do not compare it to cars. In aircraft fuel injection gave more accurate fuel distribution and often solved poor fuel/mixture distribution between cylinders. Cars without superchargers often flow more air through the injector system than through carbs. Aircraft engines with superchargers can flow more air than the engine can use below the critical height (FTH).
Sometimes engines had problems with fuel/air distribution and one cylinder could be running a lot leaner or richer than the one next to it due to manifold issues. Engine is limited to what the leanest cylinder in the engine is doing. Leanest cylinder in the engine goes into detonation first and even one cylinder blowing itself up tends to ruin the whole engine an the pilots "flight experience " for the day.

Info on the 12Z is all over the place. 2500rpm or 2600rpm or 2800rpm. Different supercharges, different supercharger gear ratios. Allowable boost?
One account says the early one was getting 1200hp with carbs. Claiming 400hp just for fuel injection seems a little generous.

And for the French, can they make hundreds of fuel injection units per month in war time?

TM06 said:

No I got what you meant, it just planted an interesting idea in my head as a potential use for those hopeless light fighters.
Something like "Well those aircraft won't do us very good as fighters, but they may be able to function well as recon!"
Gotta make do with what you have, right?

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Assuming you can get a standard recon camera to fit in the small planes.
Also assumes that the production planes come close to the performance estimates or prototype trials, something the French had a lot of trouble with in 1938-40 (so did other people).

French could have done better in 1939-40 concentrating on planes already in development/tooling rather than looking for trick low cost but limited capability aircraft.
Anything that was flying in early 1940 as a prototype was probably 1 1/2 to 2 years away from large production. The French track record for getting prototypes into production in the late 1930s was not good. 1 1/2 years is generous.

Shortround6 said:

Info on the 12Z is all over the place. 2500rpm or 2600rpm or 2800rpm. Different supercharges, different supercharger gear ratios. Allowable boost?
One account says the early one was getting 1200hp with carbs. Claiming 400hp just for fuel injection seems a little generous.

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According to Wiki:
After the initial prototypes, fuel injectors built by Lavalette-Bosch would replace the original carburettors, raising the power from 1,000 to 1,300 hp (750 to 970 kW) at sea level.
I'm unsure about the other changes to the 12ZTer to give it an extra 100 hp, but I do know that it reached 1,400 hp when France fell. Or at least, that's what I remember from my Hispano-Suiza in Aeronautics book I seem to have misplaced.

Shortround6 said:

And for the French, can they make hundreds of fuel injection units per month in war time?

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Theoretically, yeah. The industrial capacity is there but the bombing raids likely would delay major production unless France pulls some Shadow Factory shenanigans. If we go with the non-embargo route, it'd probably be ready at a reasonable time. Perhaps it'd be ready even quicker with German collaboration.

Shortround6 said:

increased finning on the cylinder head (better cooling)

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IIRC, already done on the M-82F. All other improvements (modified exhaust valve design, larger intake pipe diameter, minor supercharger design improvements, etc.) should not have had a noticeable effect on weight.

Shortround6 said:

The M-82FN gained 88kg over the M-82F and it wasn't just the weight of the fuel injection system.

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Source? According to the sources I already mentioned in my previous posts weights of the M-82 modifications were 850 kg for the M-82 (Fokin), 870 for the M-82F (Kotelnikov) and 900 (Fokin) / 910 (Sogalov) for the M-82FN. The measurement uncertainty was approximately 2% (Fokin, Sogalov).
Weight of the injection system NB3-U was ~27 kg.

TM06 said:

According to Wiki:
After the initial prototypes, fuel injectors built by Lavalette-Bosch would replace the original carburettors, raising the power from 1,000 to 1,300 hp (750 to 970 kW) at sea level.

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Beware of the weasel words ("would replace"), and unsourced stuff on the internet:
This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.

Note that already the legacy HS 12Y-51 was making 1000 HP. The Y-89 (ie. the 1st 12Z before being renamed) was supposed to make 1300 HP. See here.

TM06 said:

If the gain was only 10%, that would still mean 160 extra horsepower for the 14R which was within my calculations.

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Yes, that should be the improvement, with direct fuel injection coupled with the changes in the valve train in order to much increase the valve overlap.

TM06 said:

I couldn't exactly find much in the way of reasoning, almost everything I could find for the selected engines was "fuel injection boosted power to X". But I also don't have access to all possible sources. If you can offer any, it'd be appreciated.

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TM06 said:

- The 12Z went from 1,000 hp in its basic prototype form to 1,400 hp in the 12ZTer (400 hp increase)

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12Z gained the power due to the engine being much modified vs. the 1000 HP HS-12Y-51:
- stronger & heavier internals that allowed for the greater RPM and boost (that also took advantage of the 130 grade fuel),
- the 4-valve head
FWIW1, FWIW2

TM06 said:

- The Merlin went from 1,760 hp in the Merlin 66 to 2,060 hp in the Merlin 130 (400 hp increase)

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Mostly, if not entirely due to the use of 150 grade fuel that allowed for the increase of boost and thus the power went up.
The latest Packard Merlins gained another 200 HP over that due to the even greater boost sue to the introduction of water-alcohol injection.
See the entries for the Spitfire IX, DH Hornet and Merlin Mustang here.

TM06 said:

The Kinsei went from 1,200 hp in the Kinsei 52 to 1,350 hp in the Kinsei 62 (150 hp increase)

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Allowed fuel was now 92 oct, not 87 oct as with the Mk.52, since the bigger S/C (impeller of 12.6 in vs. 11.4; drive ratios remained the same) will be heating up the charge so the higher octane fuel will prevent detonation when the higher boost is attempted. But certainly the fuel injection should've done it's part there.
Note that water-alcohol injection added another 200+- HP (max value) on the 60 series.

TM06 said:

The Kasei went from 1,460 hp in the Kasei 11 to 1,820 in the Kasei 23 (360 hp increase)

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Anything above 1530 HP was due to the water-alcohol injection. The increase in RPM from 2450 to 2600 also played a small part in the increase of the power (perhaps 70-80 HP gain?). The bigger impeller was also introduced pretty early, from Mk.13.

For the Japanese engines, there is a big thread in the engines section (high five to Shinpachi ), I'd also recommend the TAIC manual series (several of them can be downloaded via this site, including the big one of ~300 pages).

tomo pauk said:

Yes, that should be the improvement, with direct fuel injection coupled with the changes in the valve train in order to much increase the valve overlap.

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I tried to figure out what increase of power was gained by the use of direct injection on the M-82. To be honest, I still find it challenging to answer this question. For example, G.Serov, which is a well-known researcher of the history of M-82/La-5, believes that if all the same measures were taken on the M-82A as on the FN (an increased diameter of intake tubes and exhaust valves, at least), the power could be about the same. It is also possible that the use of a Bendix-Stromberg-type injection carburetor could provide an additional (small) power gain due to an increased mass charge, even with a single-stage supercharger. But the Soviet industry failed to master the production of injection carburetors. My humble opinion is as follows: in the presence of a well-adjusted injection carburetor and optimization of injection geometry, direct injection rather does not provide a significant power gain.

bf109xxl said:

I tried to figure out what increase of power was gained by the use of direct injection on the M-82. To be honest, I still find it challenging to answer this question. For example, G.Serov, which is a well-known researcher of the history of M-82/La-5, believes that if all the same measures were taken on the M-82A as on the FN (an increased diameter of intake tubes and exhaust valves, at least), the power could be about the same. It is also possible that the use of a Bendix-Stromberg-type injection carburetor could provide an additional (small) power gain due to an increased mass charge, even with a single-stage supercharger. But the Soviet industry failed to master the production of injection carburetors. My humble opinion is as follows: in the presence of a well-adjusted injection carburetor and optimization of injection geometry, direct injection rather does not provide a significant power gain.

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Direct fuel injection was a way to make the substantial valve overlap to work. Increased valve overlap = increased power (obviously, up to a point).
If there was no change to the valve train (= basically to the camshafts in this case), the gain in power due to dir. fuel injection was probably negligible since there is no incraesed valve overlap.
The benefits wrt. the reliable and uniform fuel flow should still be felt, however

So if I understand correctly:
Just fuel injection for the 14R would boost power by ~10% to 1,760 hp, any further "quick" gains would be made through water-methanol injection, better quality / higher octane fuels (going from 92 octane to 100 octane) and increased boost?
With all that, what kind of horsepower would the 14R be making? Looking at the similar BMW 801 and ASh-82, 1,900~2,000 hp seems to be in the ballpark.

Radial air-cooled engines get very tricky.
Documentation of German and Russian engines is a little lacking in English.
Wright engines seem to be the best documented as to changes. There were 3 different R-2600 engines. about all they kept were the bore & stroke.
They went from 1500-1600hp T-O to 1700hp by changing the crankcase from aluminum to steel, changing the crankshaft, the rods, the cylinders and the cylinder heads and other stuff.
They increased the rpm by 100. From 2400 to 2500rpm.
No R-2600 was ever rated for using Water/injection. the 1700hp versions were never rated for increased power using 100/130 fuel over 100/100.
The 1900hp R-2600s got a different steel crankcase, a different crankshaft, new rods?, new cylinders with different fins and new heads. They ran at 2800rpm.
Production versions never got water injection, turbos, two stage superchargers or WER ratings. Maybe they could have and accepted shorter engine life.
All together they made over 85,000 of these engines.

There was a huge problem cooling the air-cooled engines and they were running closer to the detonation limits than liquid cooled engines were.
You can try all the tricks and get more power. The problem is getting the engine to last, needing to be overhauled at 100 hours instead of 300 hours is a problem but for a combat plane that is easier to deal with than getting shot down. However, if after a few minutes of "boosting" the engine cylinders start coming off the engine there is a totally different problem. Might be the same basic cause but the quick/easy fix doesn't work.

For the French they had gone through several traumas with radial engines in the 1930s. So did most other nations. Late 20s/early 30s engines (everybody's) used crude cylinder had head fins and there was only so much heat they could get rid of. During the 30s there was a continual race to make cylinder fins longer, thinner and more closely spaced, same for the heads. There were other problems but a lot of them got solved but the heat problem is simple physics (get rid of the heat) vs metal fabrication (machining/casting ever larger fin area).
Yes the cranks and crankcases have to able to stand the higher pressures/loads but if the cylinders overheat (and oil breaks down) things start coming apart real quick.
For the G-R company the early 14Ks were ok, but after a few years they started to get a reputation for unreliability. Or their competitors got better?
French government decided they wanted air cooled engines, so did the Italians, other countries flopped back and forth?
H-S pretty much stops development (or slows down) work on the 12Y (and 12X?) and designs the 14AA and the 14AB. The Government thinks the 14AA is the greatest thing since the croissant and plans much of their bomber program around it.

G-R is trying to play catch-up. The 14K-10 series(?) engines show better reliability but not much more power.
The H-S engines are having trouble. Lots of trouble. Using hindsight perhaps trying to make a 45.2 liter (2758 cu/in) 14 cylinder engine may not have been the smart thing to do.
Especially with a 2 bearing crankshaft. We do not have a lot of details but but there seem to have been a lot of overheating/cooling issues and forced landings. The 14AB engine (26.1 liter/1893 cu/in) is getting less attention and seems to have fewer problems, but France needs an 1100-1200hp engine, not a 700-800hp engine for their bombers.
The 12Y is sort of stagnating.
G-N is working on the 14N series of engines, still with 2 bearings but with a lot more cooling fins and a stronger construction.
After a number of years the H-S 14 AA is still pretty much a disaster and far from being ready for squadron service.
The G-N 14N is used to fill some of the gaps but is still a bit down on power.
The G-N 14M seems to be trouble free.
H-S is working on the 12Y as a fall back for the 14 AA but several years have been lost. Also a lot of sales (revenue).
By the time we get to 1939 and early 40 the 14 AA is pretty much trash and the mad scramble for substitute engines is on.
The French government also finds out the H-S 14 AB engine has problems and has to substitute the G-R 14M into many of the programs.
The French government is also trying to figure out if the newer H-S 12Y engines can be used in some of the existing bomber/recon plane designs.
Except that H-S and G-R are having trouble gearing up production. (another story).

Got a bit off track.

In order for most of these power boosting tricks to work you need two things.
1. Enough cooling capacity (fin area) to keep the engine cool while making the extra power.
2. Strong enough construction to handle the stress of the extra power.

Very few air cooled radials had the extra finning to deal with higher power (water injection does help)
very few air cooled radials had the extra strength to handle extra power (over and above design) without significant modifications.
Each cylinder on a radial is on it's own. On a V-12 adjacent cylinders can sort of the share the load at times.

The G-R 14R engine was 150-200lbs lighter than other 14cylinder engines making about the same claimed power.
Just a long term durability factor or problems in the short term for boosting power?

TM06 said:

So if I understand correctly:
Just fuel injection for the 14R would boost power by ~10% to 1,760 hp, any further "quick" gains would be made through water-methanol injection, better quality / higher octane fuels (going from 92 octane to 100 octane) and increased boost?
With all that, what kind of horsepower would the 14R be making? Looking at the similar BMW 801 and ASh-82, 1,900~2,000 hp seems to be in the ballpark.

Click to expand...

1850-1900 HP as a conservative forecast? Make it 2000 HP with water-alcohol injection?