Why was P-36 so successful in the battle of France?

[ThomasP]

In my notes I have the HS 12Z having passed its type test at 1300 ch at 2650 rpm. The report I read said this was its max output at that time (January 1940) with 1100 ch as its international rating. The report did not say what grade fuel was used for the type test.

The 1500-1600 ch 12Z variants were post-war (I think).

 

[MIflyer]

The Hisso 12Y engine was 2196 Cu In, larger than a DB601 and much larger than Merlin or V-1710. They did not produce a 1500 HP version of the engine until 1950, the purpose being to sell them to smaller countries flying the WWII fighters that needed run-out Merlins and Allisons to be replaced.

 

[Frog]

...

'' ...Overall though I'd say what the French were really missing was another 3-6 months to get ready. Maybe if they and the British had sent arms to Poland or put tanks and artillery in Belgium early on, I don't know. I'm sure delaying the war was impossible but if they had some more time, their air defense would have been quite a bit more formidable. They had ignored the problem for a long time but by late 1939 they were scrambling fast to get it together, and they had put together some nice aircraft....''

That would not have cured some flawed combat doctrines.

 

[Thumpalumpacus]

That would not have cured some flawed combat doctrines.

For those of us not aware, could you elaborate a little?

 

[Wild_Bill_Kelso]

In my notes I have the HS 12Z having passed its type test at 1300 ch at 2650 rpm. The report I read said this was its max output at that time (January 1940) with 1100 ch as its international rating. The report did not say what grade fuel was used for the type test.

The 1500-1600 ch 12Z variants were post-war (I think).

Fair enough, but given that VG-33 and D.520 were making ~340 mph with an 830 hp engine, presumably a 1,300 hp engine would be a pretty nice jump in power.

 

[Wild_Bill_Kelso]

That would not have cured some flawed combat doctrines.

I don't think France could have won the war, but it could have lasted a bit longer, especially with US aid coming across the pond. Certainly would have been a different scenario.

 

[Frog]

For those of us not aware, could you elaborate a little?

Pilots were genrally well trained but the tactics were not on par with those of the opponents. Better planes and time would have helped but also new combat concepts would also have had to be taken in consideration. What did not help too was being on the defensive side in a dynamic form of war.

 

[Shortround6]

So the D.520 is slightly bigger, slightly faster, better armed, has double the range, and is made of stressed skin instead of questionably laminated wood*. Probably better protected and armored too, and has a working radio, and a variable pitch propeller. Plus a built in fire suppression system! And slow walking communist unions or not, French planes built in 1939-40 had a much better production / manufacturing standard than what the Soviets were making probably even by late 1942.

Don't believe everything you read on Wiki.
Range -------------------1250 km ----------------------- 700 km
Range for the D.520 is at max gross weight which means using Aux fuel tanks in the wings. Using the Aux fuel tanks seems to have made the handling worse, and if you are operating at more than normal gross weight your "G" limit is lower. Speed (not so much) and climb will be worse when carrying max fuel. It offered a useful capability, much like you could put 160 gallons in a Mohawk but you don't want to fight with the rear tank full (or nearly full). Russian cruising ranges were often given at rather high throttle settings. Not the full throttle the P-39s used but often around 90% of full power. Actual fuel tank capacities may tell us more.

Guns --------------------- 1 x 20mm, 4 x 7.5mm ---- 1 x 20mm, 1 x 7.62mm

There may be a misprint here. I-26 prototype had one engine gun and four 7.62 guns and then had two taken out because of CG issue. Most early Yak-1s carried two 7.62 guns over the 20mm, some had the 20mm gun and one 12.7mm gun. The Yak wasn't carrying more firepower but it wasn't as bad as what is listed.

They definitely had a little room for improvement for the HS 12Y - they certainly had the 12Y-51 at 1,000 hp, but were already testing 1,200 hp variants (12Y-89) and the 1,600 hp 12Z which was supposed to go into the VG-39bis. The French seemed to think they were going to work and I've yet to see convincing evidence they wouldn't, eventually. The question is when, how soon could they have them working and in new planes.

The Type 89 engine was the 12Z engine. Confusing but that was Hispano-Suiza.

The 89 engine or 12Z had 4 valves per cylinder and double over head cams. The 12Ys had (unless an experimental?) had 2 valves per cylinder and SOHC.
Since most of the development work took place shortly before surrender, after the surrender, partially done in France, partially done in Spain and the Swiss striking out on their own the only part about yet to see convincing evidence they wouldn't, eventually. Has a whole new meaning. Perhaps if everything had been done in one place and not in wartime it might have gone smoother. But not only did they have new cylinder heads they had a new crankshaft and they changed connecting rods on the late model Ys. They were also trying to come up with fuel injection. They were also trying to use a new Szydlowski-Planiol supercharger that was sort of a one and 1/2 stage supercharger. there were 3 (?) axial flow impellers in front of the centrifugal impeller. They may not have had stator stages.

See; Szydlowski-Planiol Supercharger

The outlet vanes moved in the diffuser. It was this supercharger that led to all the claims for high altitude performance for some of the late model Hispano's.

Unfortunately We can look at the Russians with the Klimov M-105 series (and the M-106/M-107 and the Swiss Saurer series of engines (and some of the Spanish versions) and see that it took quite a bit of work to get some of the late model H-S engines to work, eventually. Saurer used a crankshaft 30kg heavier than the crankshaft in the 12Z, added balance weights, and put a damper in each blade (web) of the crankshaft where the 12Z only used one damper in the last blade.
The Saurer YS-2 also would not take a cannon through the hub. The Saurer wound up weighing about 1500lbs.

The French might well have been able to pull 1200hp out of the 12Z engine in 1940/41, I think they were dreaming to expect much more in service.

 

[Wild_Bill_Kelso]

Ok, so what does a 1200 ho.D.520 or VG.39 look like?

 

[tomo pauk]

Ok, so what does a 1200 ho.D.520 or VG.39 look like?

Performance-wise? Something like the MC.202, Spitfire V or Bf 109F1 or F2.

 

[Wild_Bill_Kelso]

Performance-wise? Something like the MC.202, Spitfire V or Bf 109F1 or F2.

Right. And I kind of wonder if this is partly why the Italians, Bulgarians etc. seemed to be fairly effective with these into 1943, maybe they were putting a bit better engines in them?

Even if you assume that all of Shortround6s disparagement of the HS 12-Y engines and D.520 etc. are legit, which I'm not sure I buy them all, a D.520 certainly looks fairly formidable to me especially if it gets a few more months of development and time for pilots to familiarize themselves with them.

To me that is the big "What If" for the Battle of France. If it could have been delayed maybe to fall, at least on the aviation side the French may have had a little more of an impact. On the ground side, the French had some pretty god tanks (SOMUA-S-35 had a couple of issues but if those were fixed, like the welded shut hatch, I think this thing was pretty scary for a Pz III driver) they would have had formidable armor too. The main problem was French bureaucracy, leadership and the overall organization of their military.

But the Germans relied quite heavily on their aircraft for their victory, especially Stukas, in a few key battles. If victory hadn't been so swift, the French would have had time to react, to receive aid. The US was already selling them aircraft. Is it that unlikely they may have sent bullets and gasoline? As it was I think they lost something like 1,400 planes over France? If the French had say another 90 days to familiarize themselves with new types and receive a few more of the modern planes (some of which were being built very fast, like the LeO 45) the German advantage in the air may not have been so solid.

 

[Frog]

Right. And I kind of wonder if this is partly why the Italians, Bulgarians etc. seemed to be fairly effective with these into 1943, maybe they were putting a bit better engines in them?

Even if you assume that all of Shortround6s disparagement of the HS 12-Y engines and D.520 etc. are legit, which I'm not sure I buy them all, a D.520 certainly looks fairly formidable to me especially if it gets a few more months of development and time for pilots to familiarize themselves with them.

To me that is the big "What If" for the Battle of France. If it could have been delayed maybe to fall, at least on the aviation side the French may have had a little more of an impact. On the ground side, the French had some pretty god tanks (SOMUA-S-35 had a couple of issues but if those were fixed, like the welded shut hatch, I think this thing was pretty scary for a Pz III driver) they would have had formidable armor too. The main problem was French bureaucracy, leadership and the overall organization of their military.

But the Germans relied quite heavily on their aircraft for their victory, especially Stukas, in a few key battles. If victory hadn't been so swift, the French would have had time to react, to receive aid. The US was already selling them aircraft. Is it that unlikely they may have sent bullets and gasoline? As it was I think they lost something like 1,400 planes over France? If the French had say another 90 days to familiarize themselves with new types and receive a few more of the modern planes (some of which were being built very fast, like the LeO 45) the German advantage in the air may not have been so solid.

As long as tank warfare was concerned, even with generally well armored and armed tanks, somes flaws were :
- the one or two men turret ;
- defective communications (lack of radio in tanks)
- and less well known facts were that the refueling trucks and bridge equipment were often kept too far from the fighting units compared to what the Germans did.

 

[Thumpalumpacus]

If it could have been delayed maybe to fall, at least on the aviation side the French may have had a little more of an impact.

That wasn't in the cards, though, Bill, for the same reason Sealion was cancelled: weather at that time of the year there is pretty dicey from the German perspective. Rain hampering air ops, mud hampering armor ops, etc. It favors the defensive.

Perhaps the Germans could have postponed Fall Gelb to mid-July and still have enough time to handle bidness -- remember, it basically took sixty days to knock France out -- but even this opinion of mine has the luxury of hindsight. OKH had been champing at the bit for a while to get on with it.

Remember also the postponements of the German offensive through autumn/winter 1939/1940, as well as how weather as well as fuel issues hampered Allied ops in 1944 (again, hindsight, but this had to be a consideration in German planning).

I haven't read OKH/OKW deliberations about timing in detail, but I would think the go/no-go date would be end-of-July at the latest.

 

[SaparotRob]

If the Norwegian campaign happens as in the original time, Germany is out a bunch of destroyers and a cruiser or two. Not a good position to be in when your up against the world's largest navy.

 

[Thumpalumpacus]

If the Norwegian campaign happens as in the original time, Germany is out a bunch of destroyers and a cruiser or two. Not a good position to be in when your up against the world's largest navy.

RE Sealion that was definitely a issue. But RE the hypothetical invasion of France in Sept 1940, not so much. The Germans didn't need a navy for that, but they sure as hell needed clear skies, which by that time might be hard to come by.

 

[SaparotRob]

With complete 20/20 hindsight, they were never going to able to carry out Sealion. I keep picturing the Wehrmacht crossing in paddle boats.
Now back to our regularly scheduled thread.

 

[Shortround6]

A lot depends on how fast they could fix the HS 12-Y engines.
Forget the 12Z engine.
The D 520 and the AV 33 had potential. But it was a bit more limited than some other planes.

There also had to be a lot happen in 90 days.

It is also one thing for the US to "sell" Fuel. Were the French short of fuel?
Don't bother to trot out the 100 octane fuel line of thought. The French engines that were in service weren't goin to survive 100 octane fuel and higher boost pressures.
The post war 12Z engines (and clones) were rated at about 8.6 lbs of boost even on the versions that were rated on 100/130.
The British (and Americans) were very lucky (and RR forward thinking) that the Merlin (and Allison) had the mechanical strength to stand up to the higher boost pressures.

The D. 520 had armor behind the seat. I don't believe it had protected fuel tanks. It may not have had BP glass. I would like some details about the "fire protection" system.
Was it a system to put out engine fires? Was it to safe guard against fires when starting up? It was more than many other fighters had but it may not have been protection for combat damage. In the spring/summer of 1940 very few fighters had the protection that fighters in 1941 did. But it cost. The Spitfire II with it's Merlin XII engine was very similar in performance to the Spitfire I. Most of the extra power was used up carrying extra protection (and the Spit still didn't have very well protected tanks) and operational equipment (like the IFF and aerials).
Before I am accused of being anti British the P-40 Tomahawks showing up in the fall of 1940 didn't have armor or self sealing tanks (nor did the Martlets and anytihng else the British were getting) It was a time of transition for combat aircraft and it took months if not well over year for The Germans and British to make the transition. And sometimes even then older versions in out of the way places didn't get the new improvements.

You want D 520s with extra performance? OK, stick in the 12Y-51 engine, just don't put self sealing tanks, BP glass, better radios or think about a belt feed cannon. Add a few hundred pounds and some of the performance goes away. This assumes your 12Y-51 engines perform like they are supposed to. From Wiki :

"The Swiss continued development of the MS.412 when French involvement stopped following the June 1940 Armistice. The Dornier-Altenrhein factory completed a prototype powered with a licensed-produced HS-51 12Y engine, generating 790.4 kW (1,060 hp) together with the fixed radiator and revised exhausts as tested on the MS.411, in October 1940.[4]​ The new type retained the armament changes and other improvements introduced on the D.3800.[36]​[37]​ This series was put into production in 1941 as the D-3801 with continued deliveries until 1945 with 207 completed. Another 17 were built from spares between 1947 and 1948.[36]​ Reliability of the new engine was at first extremely poor, with problems with crankshaft bearings causing several accidents. The engine problems slowed deliveries, with only 16 aircraft produced in 1942 and a single aircraft delivered in 1943. The engine problems were eventually resolved in 1944.[37]​ With 790.4 kW (1,060 hp) from the Hispano-Suiza 12Y-51, the speed was boosted to 534 km/h (332 mph),"

It took the Swiss over two years to fix the HS-51 12Y engine. It wasn't going to happen in 90 days in France.

There were reasons the H-S engines were so light. But those reasons also severely limited development potential. Up until the -51 engines the H-S engines were limited to 2400rpm.
The H-S crankshafts had dampers but were "totally devoid of counterbalances". * H-S engines were built with the use of exiting production machinery very much in mind. The 12Y used the same 170mm bore spacing as the 300hp V-8 of WW I.
The -51 engine got bigger intake valves (one per cylinder) and they allowed an extra 100 rpm for max power. But it called for redesigned camshafts to make them more rigid and added reinforcement to the top and bottom of the crankcase. The -51 engine picked up about 10 kg in weight over the earlier versions because of the reinforcements.
In 1938 H-S made an offer to Alfa Romeo to license the -51 engine including the supply of H-S production machinery. Alfa Romeo didn't take them up on it.

The bore spacing thing is one reason the Russian engines used a 148mm bore instead of the H-S 150mm bore. Think about it. The H-S engine had 20mm for two cylinder walls and the water jacket.
The H-S engine was a very good engine for the late 1920s and early 30s. By 1938-39 it was like trying bring back the Curtiss Conqueror (which in many ways was a more modern engine).

 

[Shortround6]

As long as tank warfare was concerned, even with generally well armored and armed tanks, somes flaws were :
- the one or two men turret ;
- defective communications (lack of radio in tanks)

Quite right.
The German tankers sure didn't like the SOMUA-S-35 but it needed a lot more fixing than welding up a hatch.
The S-35 had sort of a 1 1/2 man turret, the radio operator sat/stood in the hull and passed ammo up to the commander/gunner so he didn't have to reach as far for it. French radio production did not keep up with demand so many of the S-35s didn't have radios.

 

[Wild_Bill_Kelso]

The radios were basically due to a shortage. The S-35's performed quite well in combat, but I think the biggest (and strangest) problem was that the hatch was welded shut.

 

[Wild_Bill_Kelso]

A lot depends on how fast they could fix the HS 12-Y engines.
Forget the 12Z engine.
The D 520 and the AV 33 had potential. But it was a bit more limited than some other planes.

There also had to be a lot happen in 90 days.

It is also one thing for the US to "sell" Fuel. Were the French short of fuel?
Don't bother to trot out the 100 octane fuel line of thought. The French engines that were in service weren't goin to survive 100 octane fuel and higher boost pressures.

No I wasn't thinking about 100 octane I just meant the Americans could have started sending 'butter and beans' ... and fuel and bullets and lots of other stuff, if the war had lasted more than 60 days. Especially if it started a bit later.

The post war 12Z engines (and clones) were rated at about 8.6 lbs of boost even on the versions that were rated on 100/130.
The British (and Americans) were very lucky (and RR forward thinking) that the Merlin (and Allison) had the mechanical strength to stand up to the higher boost pressure


The D. 520 had armor behind the seat. I don't believe it had protected fuel tanks. It may not have had BP glass. I would like some details about the "fire protection" system.
Was it a system to put out engine fires? Was it to safe guard against fires when starting up? It was more than many other fighters had but it may not have been protection for combat damage. In the spring/summer of 1940 very few fighters had the protection that fighters in 1941 did. But it cost. The Spitfire II with it's Merlin XII engine was very similar in performance to the Spitfire I. Most of the extra power was used up carrying extra protection (and the Spit still didn't have very well protected tanks) and operational equipment (like the IFF and aerials).
Before I am accused of being anti British the P-40 Tomahawks showing up in the fall of 1940 didn't have armor or self sealing tanks (nor did the Martlets and anytihng else the British were getting) It was a time of transition for combat aircraft and it took months if not well over year for The Germans and British to make the transition. And sometimes even then older versions in out of the way places didn't get the new improvements.

You want D 520s with extra performance? OK, stick in the 12Y-51 engine, just don't put self sealing tanks, BP glass, better radios or think about a belt feed cannon. Add a few hundred pounds and some of the performance goes away. This assumes your 12Y-51 engines perform like they are supposed to. From Wiki :

"The Swiss continued development of the MS.412 when French involvement stopped following the June 1940 Armistice. The Dornier-Altenrhein factory completed a prototype powered with a licensed-produced HS-51 12Y engine, generating 790.4 kW (1,060 hp) together with the fixed radiator and revised exhausts as tested on the MS.411, in October 1940.[4]​ The new type retained the armament changes and other improvements introduced on the D.3800.[36]​[37]​ This series was put into production in 1941 as the D-3801 with continued deliveries until 1945 with 207 completed. Another 17 were built from spares between 1947 and 1948.[36]​ Reliability of the new engine was at first extremely poor, with problems with crankshaft bearings causing several accidents. The engine problems slowed deliveries, with only 16 aircraft produced in 1942 and a single aircraft delivered in 1943. The engine problems were eventually resolved in 1944.[37]​ With 790.4 kW (1,060 hp) from the Hispano-Suiza 12Y-51, the speed was boosted to 534 km/h (332 mph),"

It took the Swiss over two years to fix the HS-51 12Y engine. It wasn't going to happen in 90 days in France.

There were reasons the H-S engines were so light. But those reasons also severely limited development potential. Up until the -51 engines the H-S engines were limited to 2400rpm.
The H-S crankshafts had dampers but were "totally devoid of counterbalances". * H-S engines were built with the use of exiting production machinery very much in mind. The 12Y used the same 170mm bore spacing as the 300hp V-8 of WW I.
The -51 engine got bigger intake valves (one per cylinder) and they allowed an extra 100 rpm for max power. But it called for redesigned camshafts to make them more rigid and added reinforcement to the top and bottom of the crankcase. The -51 engine picked up about 10 kg in weight over the earlier versions because of the reinforcements.
In 1938 H-S made an offer to Alfa Romeo to license the -51 engine including the supply of H-S production machinery. Alfa Romeo didn't take them up on it.

The bore spacing thing is one reason the Russian engines used a 148mm bore instead of the H-S 150mm bore. Think about it. The H-S engine had 20mm for two cylinder walls and the water jacket.
The H-S engine was a very good engine for the late 1920s and early 30s. By 1938-39 it was like trying bring back the Curtiss Conqueror (which in many ways was a more modern engine).

I think they did have self sealing tanks and some armor on the D.520, not sure about BP glass.

I think the details of the production schedule of the Swiss engine production is interesting, but not necessarily salient, as this Swiss branch of Hispano Suiza was a small part of the larger firm, and while they probably had a lot of the expertise, they had a much, much smaller population and industrial base than France (four million vs forty million). France had been building fairly large numbers of aircraft since WWI, I don't think Switzerland ever did. The Swiss were lacking in resources and also highly isolated in the center of Europe during the war. I think some (probably most) of the trouble they had can be attributable to that.

All high performance engines had teething problems but I again, don't really see anything here that convinces me that the French couldn't get 1,200- 1,300 hp out of their 12Y in 1940 or 41. To know more we'd really have to look at French records.