Luftwaffe vs. IJA

[wiking85]

The Japanese didn't have much of a need for foreign engines. The Nakajima Homare used on the Ki 84 for instance could produce 2000hp yet was only 46 inches in diameter. The Bristol Hercules and CW R-2600 were both 55 inches for less power. The PW R-2800 maybe 52.5 inches and the BMW801 51.5 inches. late war the Japanese seem to have developed several functional turbo supercharger designs.

They seem to have had trouble mass producing efficiently. Their designs tended to emphasise manoeuvrability via big wings, which means nothing if your opponent is faster and doesn't want to engage. To truly exploit a speed advantage you need a fast bomber as well as a fast fighter. An Me 410 while slower than a Spitfire or Mosquito might be a real trouble maker for the slower Japanese if used to dive bomb shipping or IJN outposts.

Overall the IJN is simply much bigger and would win, just as the Heers masses Panther tanks would demolish the Japanese armour.

The Homare was a troubled engine and wasn't able to generate near its spec in practice until 1944-45, but still only producing around 1800hp.
Nakajima Homare - Wikipedia, the free encyclopedia
Also without a war with the Soviets there is not going to be a Panther design, rather a VK3001.

I'm just wondering how the Germans would manage to get heavy armor into the far east. We can't just say that the Germans manage to wander into China, set up massive factories and start producing an endless stream of Tigers, Panthers, StuGs and the like without being challenged by the Japanese at some point.

And the Japanese had small tanks because the predominant terrain dictated smaller tanks. If the Japanese felt the need to manufacture and deploy heavy armor, they would have done so.

They won't. At best they are going to field a substantial air element with ground defense for it. If they cozy up to the Soviets then they can get an uninterdictable supply line around the IJN. If somehow they can work out their issues with the Allies then they could use Indochina, because without the war in Europe Japan is not going to move into there.

 

[tomo pauk]

The Japanese didn't have much of a need for foreign engines. The Nakajima Homare used on the Ki 84 for instance could produce 2000hp yet was only 46 inches in diameter. The Bristol Hercules and CW R-2600 were both 55 inches for less power. The PW R-2800 maybe 52.5 inches and the BMW801 51.5 inches. late war the Japanese seem to have developed several functional turbo supercharger designs.

Lets do some timeline here; power vs. altitude would0ve helped us also.
The Homare was next to incapable to produce 2000 CV prior 1945? By what time Hercules 100 series can do 1800 CV in 1st gear and 1650 CV at 20000 ft (link), while finally having the 'proper' ejector stacks installed. 1900 HP R-2600 is also there, though it is not that good at higher altitudes. P&W 2-stage 'C' series engine is vastly superior at any altitude.
Japanese aircraft with turbo charged engines never flew a combat sortie, let alone scored a hit on something?

They seem to have had trouble mass producing efficiently.

Very true.

Their designs tended to emphasise manoeuvrability via big wings, which means nothing if your opponent is faster and doesn't want to engage. To truly exploit a speed advantage you need a fast bomber as well as a fast fighter. An Me 410 while slower than a Spitfire or Mosquito might be a real trouble maker for the slower Japanese if used to dive bomb shipping or IJN outposts.

Yep, Japanese have had no answer for a fast bomber until 1945, even then for the Mossie with a 2-stage engine.
Mid- and late-war Japanese fighters did not have such a big wings, though, however the engine power meant those fighters were hard pressed to beat 600 km/h mark, let alone 650 km/h (Ki-84 in 1945 maybe?).

Overall the IJN is simply much bigger and would win, just as the Heers masses Panther tanks would demolish the Japanese armour.

Masses of Panther tanks in Asia? That's a good one

 

[fastmongrel]

If the Germans are somehow going to get Panthers as far as China they had better have a lot of bridging equipment and heavy movers, even a PzII tankette would be too heavy for most bridges.

 

[Shortround6]

Masses of Panther tanks in Asia? That's a good one

Easy, they are shipped in on cargo submarines.

Lots and lots of cargo submarines.

 

[GrauGeist]

If somehow they can work out their issues with the Allies then they could use Indochina, because without the war in Europe Japan is not going to move into there.

Doubtful...The area in and around Indochina had a large French colony presence and they would want to avoid involvement. This would include Cambodia, Laos and Vietnam. Burma and several other areas were British. On the otherhand, Thailand (Siam) was aligned with Imperial Japan.

In otherwords, allowing German access through their colonial territory would be taken as complicity by the Japanese and upset the "neutrality". If Russia allowed access to the far east, the "difficult peace" between Japan and Russia would be upset.

So Germany would really be having a hard time in getting any substantial assets into the China theater without upsetting the applecart.

 

[wiking85]

Doubtful...The area in and around Indochina had a large French colony presence and they would want to avoid involvement. This would include Cambodia, Laos and Vietnam. Burma and several other areas were British. On the otherhand, Thailand (Siam) was aligned with Imperial Japan.

In otherwords, allowing German access through their colonial territory would be taken as complicity by the Japanese and upset the "neutrality". If Russia allowed access to the far east, the "difficult peace" between Japan and Russia would be upset.

So Germany would really be having a hard time in getting any substantial assets into the China theater without upsetting the applecart.

Without a threat from Germany the Soviets have little to fear from the Japanese and in fact stand to gain quite a bit by having China ultimately win, as their assistance (which historically was only called off due to the German-Japanese alliance and Soviet work with the Germans) would be remembered and until 1945 Chiang and Stalin were closer than Mao and Stalin. In fact Mao and Stalin disliked each other. Japan and the USSR had issues with each other and Stalin stood to gain from their weakening due to the war in China. So Stalin, assuming that the Germans and Soviets cut a deal in 1939, would be totally on board and in fact may well facilitate the move west of Chinese raw materials to pay for German weapons and aid, while getting the Germans to fulfill their historical trade deals as payment.

 

[Conslaw]

The Germans would have had the same logistical problems in getting supplies into China that the Western Allies had. Maybe worse, because they wouldn't have India as a jumping-off point. Even if they could have used Russia's Trans-Siberian railroad, they wouldn't have had the capacity for an unfettered campaign in China.

As far as aircraft go. The zero would have likely held its own in 1-1 battles with the bin Bf-109E. The Zero was similar to but superior to the Curtis Hawk 75 that the French used successfully. The problem is numbers. The handful of pre-production zeros that fought in China so successfully in the summer of 1940 were all that were in existence at the time. Production was ramped up slowly, but by December 1941, there were only about 300 deployed. The IJA's Ki-43 (Oscar) was not even in service at that level. Those aircraft, and a handful of service-test Ki-44s were all the modern fighters that Japan had. By December 1941, the Germans had the Bf-109F and production models of the FW-190A.

 

[wiking85]

The Germans would have had the same logistical problems in getting supplies into China that the Western Allies had. Maybe worse, because they wouldn't have India as a jumping-off point. Even if they could have used Russia's Trans-Siberian railroad, they wouldn't have had the capacity for an unfettered campaign in China.

As far as aircraft go. The zero would have likely held its own in 1-1 battles with the bin Bf-109E. The Zero was similar to but superior to the Curtis Hawk 75 that the French used successfully. The problem is numbers. The handful of pre-production zeros that fought in China so successfully in the summer of 1940 were all that were in existence at the time. Production was ramped up slowly, but by December 1941, there were only about 300 deployed. The IJA's Ki-43 (Oscar) was not even in service at that level. Those aircraft, and a handful of service-test Ki-44s were all the modern fighters that Japan had. By December 1941, the Germans had the Bf-109F and production models of the FW-190A.

Unfettered no, which is why I think they will only get a reinforced air corps into China. The Zero was significantly slow, so as long as they don't dog fight and learn as well as the Flying Tigers, which shouldn't be hard given that the LW was far more experienced at this point, they would do great. Also the Zero was just with the IJN, so as long as they stay away from the coast they aren't going to encounter them. And it wasn't introduced until July 1940, so the Germans wouldn't encounter it until then and probably only in limited numbers due to the fact it was just introduced, as you note. Really the E and then F would have the rule of the roost. Plus the Ju88 when it shows up would be so fast as to give the early Japanese fighters a run for their money. The Fw190 would just dominate anything the Japanese produced. Later when the fighter-bomber variant shows up it can outrun anything the Japanese had until 1944-45.

 

[FLYBOYJ]

Tactics, Tactics, Tactics....

In this hypothetical situation, if the Germans would have engaged the Zero below 250 mph, they would have been mauled, just like everyone else at the beginning of the war. Something tells me however, given this hypothetical situation, they would have learned very quickly!!!

 

[wiking85]

Tactics, Tactics, Tactics....

In this hypothetical situation, if the Germans would have engaged the Zero below 250 mph, they would have been mauled, just like everyone else at the beginning of the war. Something tells me however, given this hypothetical situation, they would have learned very quickly!!!

Given the same situation would exist with existing Japanese fighters prior to the Zero, they'd probably keep the same tactics learned in 1939-40 and apply them to the Zero. As it was the Soviet fighters in Spain had the same advantage and the Bf109 was able to dominate anyway.

 

[Shortround6]

Assuming the Germans have a supply route they can probably keep a Condor legion type air group going in China.

This air group could very well dominate the IJA where it met in combat.

What effect this would have on the overall campaign/war might be subject to question. China is a big country. It is almost the same distance from Beijing to Hong Kong as it is from Stockholm to Rome. The Japanese have the advantage of choosing where they will strike (at least to some extent). The German Legion, without multiple bases and complicated logistics would be much more tied to a few areas. Radar is somewhat less important than in Europe. You need a lot more of it and since most of the air attacks took place over land a telephone based observer system actually worked fairly well for early warning/raid tracking.

The greater range of the Japanese aircraft allow for greater flexibility in target choices.

 

[kool kitty89]

The Homare was a troubled engine and wasn't able to generate near its spec in practice until 1944-45, but still only producing around 1800hp.
Nakajima Homare - Wikipedia, the free encyclopedia

The 1200~1600 HP class engines would be the ones to realistically look at for the early.mid war period. Namely the Mitsubishi Kinsei, the larger Kasei, and Nakajima's Ha41/Ha109. The only reason engines really came up was in regards to the Ki-60/61 and whether they'd use an alternate inline design or resort to an earlier counterpart to the Ki-100. (the Kasei would have delivered similar power much earlier than the Ha-112 the Ki-100 used, but was bulkier and heavier. A lighter engine in the 1200-1300 hp range should have been possible earlier (at least around the time the Ki-44 came online). Either way these sorts of developments aren't really going to be relevant until around 1942.

With stronger opposition from faster, more heavily armed aircraft, some developments might have been pushed sooner, maybe with earlier engines but still some gains from greater emphasis on armor, self sealing, and speed over maneuverability. If the Ki-27 was taken down in droves by significantly less maneuverable aircraft in 1939/1940, the Ki-43 might have not existed as it did in 1941 (armament included), and the A6M might have seen design modifications earlier.

That or the Ki-43 might have been passed over in favor of some (hypothetical) competing design, say the 1940 counterpart to the Ki-28 that lost to the significantly slower Ki-27.

Also without a war with the Soviets there is not going to be a Panther design, rather a VK3001.

Given the timing, even STUG IIIs wouldn't be available initially, regardless of the ability to actually get them to the front lines. Panzer IIIs would be the only thing available, and even those would have been scarce if production hadn't ramped up (and ramping up production to support China is a bit different than planning to invade France).

That said, with the lighter Japanese tanks as the main opposition, the Panzer III seems like it would fit fairly well even as a tank destroyer. It might actually be too heavy for some of the terrain being dealt with in the region, and with the older Panzer II and Panzer 35 available in greater numbers (and easier to transport to the front lines), those might have been the more significant tanks of the early war. (the Panzer I seems less useful, but might have been pressed into service as well)

Doubtful...The area in and around Indochina had a large French colony presence and they would want to avoid involvement. This would include Cambodia, Laos and Vietnam. Burma and several other areas were British. On the otherhand, Thailand (Siam) was aligned with Imperial Japan.

In otherwords, allowing German access through their colonial territory would be taken as complicity by the Japanese and upset the "neutrality". If Russia allowed access to the far east, the "difficult peace" between Japan and Russia would be upset.

So Germany would really be having a hard time in getting any substantial assets into the China theater without upsetting the applecart.

How different would that be than support (or merchant ships) originating from other officially neutral countries during early WWII? (particularly all the countries American firms were selling weapons to) Or various countries supplying Finland with military equipment during the Winter War. Hell, I'm not even talking about Britain/France/etc SELLING weapons to China, but allowing passage through their territory ... or at very least for allowing certain material transports to pass through, including any return payment from China.

More so if there was also a passage available though Russia, meaning the indochina route would be auxiliary.

It seems like getting troops clear passage would be the bigger issue. Though some political finagling with merchant ships and trade routes supplying military equipment being /sold/ to China along with /volunteer/ personnel taking whatever passage they could arrange, more options might open up.

Easy, they are shipped in on cargo submarines.

Lots and lots of cargo submarines.

And yes ... in jest or not, some supplies could be sent by submarine ... more so if dedicated transport submarines were emphasized ... and if they were allowed to stop at neutral ports as 'merchant ships.'

But that's of course only remotely realistically useful if merchant shipping to China was totally impossible to manage without unsustainable losses. (and either way, you need access to secure ports on the Chinese coast to unload the cargo and vector it to where it's needed)

Unfettered no, which is why I think they will only get a reinforced air corps into China. The Zero was significantly slow, so as long as they don't dog fight and learn as well as the Flying Tigers, which shouldn't be hard given that the LW was far more experienced at this point, they would do great.

Not to mention the MGFFs of the 109E would shred Zeros, Ki-43s, and Ki-27s even faster than the .50s on the P-40B/C. (and significantly easier than the Hurricane, Spitfire, and some of the French aircraft the 109 historically faced)

That said, the 109 probably wouldn't have been able to absorb the damage the P-40 could, and range/endurance was substantially less, as was maneuverability at high speeds. (albeit still considerably better than the japanese fighters -along with higher G limits and maximum allowable dive speeds)

The Fw190 would just dominate anything the Japanese produced. Later when the fighter-bomber variant shows up it can outrun anything the Japanese had until 1944-45.

With conflicts in Europe foregone or delayed indefinitely (along with political changes within Germany), development of the Fw 190 may have changed as well, on top of the Fw 187.

With the relative performance of Japanese aircraft and requirements for that theater of operations, aside from the Fw 187 being reconsidered as a single-seat long-range fighter (and also one able to use up remaining stock of Jumo 210 engines and still provide compelling performance), you also have potentially greater emphasis on extending the Fw 190's range, or at least developing long range derivatives. Making room for more fuel and/or possibly even replacing the BMW 801 with a DB 601E (with ease of flying, range, armament and cockpit visibility all being advantages over the 109F) should have been realistic options, and even if eliminating the wing root or outer wing guns in favor of more fuel tankage, you'd still have some margin for a heavier armament than the 109. (even before the MG 151 was available, you could eliminate the inner wing guns in favor of fuel tanks and -in the case of the 601E, add a 3rd MG-FF/M in the nose, to be replaced by 151 or 151/20 later -or again, use the outer wings for fuel and focus on the centerline armament)

A DB-601E powered Fw-190A derivative might not have been as fast as the 109F (and almost certainly would climb worse), but it should have comprehensively outperformed the P-40B/C/E and even F while having more firepower and similar range. (probably similarly easy to fly, definitely easier than the 109, and likely easier than the 801 powered 190 due to lower weight/wing loading and torque)

Given the same situation would exist with existing Japanese fighters prior to the Zero, they'd probably keep the same tactics learned in 1939-40 and apply them to the Zero. As it was the Soviet fighters in Spain had the same advantage and the Bf109 was able to dominate anyway.

The Jumo 210 powered 109 variants employed there were significantly lighter than the 109E and were much slower. That said, the situation with the Bf 109E compared to the Hurricane Mk.I should at least be relevant as well, at least in terms of turn ability and roll performance being compromised at high speeds. (though not quite the same structural issues as the Japanese fighters, aside from very early Hurricane I's having wing fabric deformation issues, they probably handled high speed dives better than these japanese fighters, and certainly took more structural damage) The 109E would similarly have better dive acceleration than any of those, hurricane included. (better level acceleration and climb compared to some of them as well)

 

[wiking85]

I'd just add that the Bf110 would be the first heavy fighter with range to be available, which would be faster than any Japanese aircraft other than the Zero until the F-series is available. It would have serious trouble with the Zero, but that wouldn't really be that much of an issue until 1941-42, but by then the F-series is available. It would be a solid fighter-bomber and long range fighter/bomber destroyer until enough Zeros show up.

 

[kool kitty89]

I'd just add that the Bf110 would be the first heavy fighter with range to be available, which would be faster than any Japanese aircraft other than the Zero until the F-series is available. It would have serious trouble with the Zero, but that wouldn't really be that much of an issue until 1941-42, but by then the F-series is available. It would be a solid fighter-bomber and long range fighter/bomber destroyer until enough Zeros show up.

The BF-110 still had a pretty limited range without drop tanks, just not as terrible as the 109. Speed was decent enough to run away from most early Japanese fighters and firepower would make it good in the bomber destroyer and ground attack roles at least. (and actually useful in the bomber destroyer role) The defensive armament might be a bit more deadly to IJA forces than it was against the British and French as well, especially given how long on target the lightly armmed IJA fighters would need to be to take down a 110) The ability to re-load MGFF drums in-flight was the sole practical advantage of the 110 over the 187, and as an early-war bomber interceptor it might have actually fared well over China.

Early war, the Ju 88 would still be the fastest airframe capable of carrying radar for night fighting abilities, though.


Edit:
One additional note on the Fw 187 that's not usually argued in its favor would be that it's the only historical early war aircraft that stood any chance of being a competitive day fighter using the remaining stock of Jumo 210 engines, and the only fighter that could likely stay competitive using Jumo 211s. (on top of the advantages in range and -at least hypothetically- firepower) In this scenario, with no European War and production scaled back, the use of the Jumo 210 is probably more significant. (adapting it to use stocks of the 1000/1200 PS Bramo 323 might have been attractive too -also likely the only fighter design in Germany that could have been competitive using that engine)

 

[wiking85]

Messerschmitt Bf 110 â€" Wikipedia

Range: 1300 km

Better than the Fw190. With external tanks that increased to 1500 miles.

Also we forgot to mention the advantage the DB601 with its supercharger had over the Japanese engines. That gives fighters equipped with it a distinct height advantage. Same with any He111Ps equipped with it too.

 

[Shortround6]

I am not sure what advantage the DB601's supercharger had over the Japanese engines in 1939-41.

The early DB 601 engines had critical (FTH) altitudes of 3700-4900 meters. Granted that beats the 9 cylinder radials by a fair amount but the early single speed 14 cylinder radials had similar FTLs. Ki-43-I was 3400 meters and the similar engine in the A6M2 was rated at 4200 meters. Engine in the early service trial Ki 44s was rated at 3700 meters ( 1260hp). Engines in the early Ki 21 bombers (in service 1938?-1940) were good for 4000 meters. Single speed Kinsei radials were good for up to 1070hp at 4200 meters although that cut take-off power to 930hp compared to the 1000hp take-off but 990hp at 2800 meter model.

DB601 didn't really have a very good supercharger. Putting a powerful engine in a light airplane can give good altitude results but then that's what the Japanese were doing anyway.

 

[wiking85]

I am not sure what advantage the DB601's supercharger had over the Japanese engines in 1939-41.

The early DB 601 engines had critical (FTH) altitudes of 3700-4900 meters. Granted that beats the 9 cylinder radials by a fair amount but the early single speed 14 cylinder radials had similar FTLs. Ki-43-I was 3400 meters and the similar engine in the A6M2 was rated at 4200 meters. Engine in the early service trial Ki 44s was rated at 3700 meters ( 1260hp). Engines in the early Ki 21 bombers (in service 1938?-1940) were good for 4000 meters. Single speed Kinsei radials were good for up to 1070hp at 4200 meters although that cut take-off power to 930hp compared to the 1000hp take-off but 990hp at 2800 meter model.

DB601 didn't really have a very good supercharger. Putting a powerful engine in a light airplane can give good altitude results but then that's what the Japanese were doing anyway.

The 601N had a rated altitude of 4900m in 1940, while the two speed Sakae 21 didn't show up until April 1942 in limited numbers. That gives the Me109 a pretty solid height advantage, especially with the F-series' other serious advantages.

 

[wiking85]

Also, as already noted by another poster China is big and there aren't enough Zeroes to go around for all the IJA and IJNs demands, especially if they get into a conflict with the US or other European powers over sanctions in 1941-42.

 

[FLYBOYJ]

Given the same situation would exist with existing Japanese fighters prior to the Zero, they'd probably keep the same tactics learned in 1939-40 and apply them to the Zero. As it was the Soviet fighters in Spain had the same advantage and the Bf109 was able to dominate anyway.

And again, a lot of that was based on tactics.

From another forum...

"The I-16 Type 5 was about 20 kph slower than the BF-109B (390 kph vs 405-410 kph at SL, 445 kph vs 460-465 kph best att), it had an inferior dive speed and early models suffered from wing structure failures during dives (particullary while pulling up from them), although this was latter corrected (most I-16's the BF-109's confronted were latter production Type 5's and Type "6's") the I-16 remained a worse diver than the heavier and more aerodynamic BF-109's, the I-16 Type 5 had also a quite obtrusive cockpit (which is the reason why pilots usually flied with it open as well as because it's tendency to snap open when maneuvering) and a had more crude telescopic gunsight with a much smaller FOV than the BF-109's reflector sight, the BF-109's Jumo 210Da engine had a better performance than the I-16's M-25A at high attitude too.

The I-16-5 did however hold a few important advantages over the BF-109B, it had a noticeably better climb rate up to at least 5,000 meters (850 m/min to 3,000 meters and 701 m/min to 5,400 meters vs 612 m/min to an unspecified att), a better power-to-weight ratio (0,464 hp/kg vs 0,32 hp/kg both at combat weight), a lower wing-loading (103,7 kg/sqm vs 131 kg/sqm), had a better roll rate, was an overall smaller target and it's radial engine was overall sturdier than the BF-109's in-line.

Armament was comparable, the BF-109 carried more ammo and the I-16 had guns with a faster fire rate, the BF-109B was sometimes equipped with a third MG-17 that fired through the propeller hub but it was unreliable and sometimes damaged the engine, the I-16 guns sometimes suffered from jamming problems and sometimes they freezed when flying at high attitude, both problems were eventually fixed, the former by putting the Shkas machineguns upside down and the latter by pouring engine exhaust fumes via plumbing to the gun mounts, some I-16's were apparently fitted with a third Shkas machinegun under the engine cowling.

All in all it could be said that the BF-109 could disengage by diving away but so could the I-16 by climbing higher (particullary at low attitudes), if the BF-109 dived away it would have a harder time climbing up to attitude again. The I-16 would also had an advantage in a horizontal fight while the BF-109 would had the advantage in a sustained vertical one, however in a short vertical engagement the superior power-to-weight ratio of the I-16-5 might be enough to keep up and/or catch up with the BF-109B (as combat experience showed, but that's another matter), also, pilots from both sides noted that, in general, the I-16 held most advantages over the BF-109 other than speed up to 3,000 meters while the BF-109 started to take the lead above that attitude.

The BF-109C was fitted with a slightly more powerful engine the Jumo 210Ga with direct injection which had an additional 20HP at take-off power and was also slightly more powerful at higher attitudes, it also had a superior armament, two over the cowling and two on the wings those changes however made the plane somewhat heavier, that meant that it was inferior to it's predecessor in most horizontal maneuvers while better at energy tactics due to it's better engine performance and slightly heavier weight, it also was slightly faster (420 kph vs 405-410 kph at SL and 470 kph vs 460-465 kph at best attitude). All in all it was the first BF-109 that had a better armament than "contemporary" I-16's (4 MG-17's vs 2 Shkas on Type 5 and 3 on Type "6"), and it held over them more or less the same exact advantages the B had, however only a handful (5?) were sent to Spain and shortly after they arrived the I-16 Type 10 made it to the front line (Early 1938 ).

Now the I-16 had regained armament parity with the best armed BF-109's (it carried 4 Shkas machineguns with a faster fire rate, but still a little bit less ammo) while it had received a more up to date reflector gunsight, a better structural integrity and a better climb rate and top speed than previous I-16's, now the difference of speed with the BF-109'Bs was narrowed even further (395 kph vs 405-410 kph at SL and 450-455 kph vs 460-465 kph best att), while they were not enough BF-109C's to replace them, so it's no coincidence that the arrival of the Type 10 was more or less coincident with an increase of BF-109's combat losses, only the introduction of the finger four tactics and more refined energy fighting tactics allowed the Condor Legion to still fight effectively, regardless by Mid 1938 the number of operational BF-109's was in it's lowest since the plane entered service in Spain.

Then the Condor Legion received a batch of 37 BF-109D's (Mid 1938 ) this model was designed to be able to mount with a much more powerful DB600Aa engine but due to the fact that this engine was scarce, it seems that most (if not all) BF-109D's sent to Spain were equipped with the same carbureted Jumo 210Da as the BF-109B's (although some of them may had been fitted with Jumo 210Ga's as those used on the C variant), they were also considerably heavier and draggier than previous BF-109's and as such the top speed performance remained the same or slightly worse than the BF-109B, however the performance of the aircraft at high attitudes was still noticeably better than that of the I-16's which was to became the main asset of the Condor Legion from now on, at low attitudes they couldn't outclimb the I-16 and they could barely outspeed them but up-high they hold a speed and even climbrate advantage as well as having enough space to dive away if they had to.

The Republicans didn't stand with they're arms crossed however, by September 1938 they had managed to illegally import several American built Wright - Cyclone SGR 1820 F-54 engines which were equipped with superchargers, although the engine somewhat decreased the plane's performance at low att it also increased it by quite a big margin at high attitude, now the BF-109D's could still outrun (barely) but not outclimb the I-16 Type 10's with this engine even at high attitudes, it is unknown how many I-16's with this modification were built although it is thought that there were probably about a dozen, those modified planes cause a great deal of concern to the Condor Legion which saw them as a considerable threat, however they were too few of them and the Condor Legion still employed superior tactics and had overall more skilled pilots than the Republic did by that time.

By January-February 1939 a shipment of BF-109E's (around 40) was sent to Spain, by that time all major combat operations had ceased but they still were employed to strafe retiring enemy columns and airfields, the plane had a considerably superior top speed to the I-16's and previous BF-109's and was the first BF-109 that could outclimb them even at low attitude which left the I-16 with very few chances (like forcing the BF-109 in a horizontal turnfight), ironically, while I haven't managed to find any confirmed I-16 air victory over an Emil in Spain, there was at least one acknowledge loss by the Legion Condor to an I-15 whose pilot actually claimed to shot down two Emils during the engagement (?!), but again that's another matter.

TL;DR Version: The BF-109 and the I-16 had, through most of the Spanish Civil War (until 1939) a comparable performance with one holding some advantages over the other that they could exploit to beat each other, however the Condor Legion had developed superior tactics and had overall better pilots. I also would add that it's pretty hard to compare the victory and loss claims done by both sides since they used a different systemology to classify combat losses and there was a significant case of over-claiming by both sides during the war."

Bf 109 B/C/D vs. Polikarpov I-16 type 5/10 - Axis History Forum

 

[Shortround6]

The 601N had a rated altitude of 4900m in 1940, while the two speed Sakae 21 didn't show up until April 1942 in limited numbers. That gives the Me109 a pretty solid height advantage, especially with the F-series' other serious advantages.

All very good in theory but in practice the DB601N was spread pretty thin. From Kurfurst's site. A report at a meeting on the 22nd of Jan 1941 detailing the numbers of aircraft equipped with DB601Ns as of Jan 1 1941.

in Bf 109s
Bf 109E-1 : 16 pcs, Bf 109E-3 : 1 pc, Bf 109E-4 : 54 pcs, Bf 109E-6 : 1 pc, Bf 109E-7 : 34 pcs, Bf 109E-8 : 2pcs. Bf 109F-1 : 5 pcs.
total 112 Bf 109s with DB601N engines.

in Bf 110s
Bf 110C-1 : 4 pcs, Bf 110C-4 : 40 pcs, Bf 110C-5 : 12, Bf 110C-7 : 14 pcs, Bf 110D-0 : 18 pcs, Bf 110D-2 : 20 pcs, Bf 110D-3 : 8 pcs, BF 110E-1 : 176 pcs, Bf 110E-2 : 14 pcs.
total 153 Bf 110s with DB601N engines. 306 engines.

and in Misc. types
He 111P : 8 pcs, Do 215 : 68 pcs. another 76 engines.

Will German send their best to China or keep the best at home?

The DB601N also needs C3 fuel.

And how big is this China Legion? A group of bombers (3-4 squadrons) and a Group of fighters (3-4 squadrons) with a few auxiliary squadrons, similar to the Condor Legion in size or a Massive Luftflotte?

China was a logistical nightmare. And just getting supplies to China (anywhere in China) was no picnic. From the US to Karachi could take 2 months by ship, getting across India from Karachi to Assam could take another 2 months and then you have to get the supplies into China and then from the Chinese supply base/s to the front lines. Things were a bit easier while the Burma road was open but that was no picnic either and required lots of trucks ( which frequently broke or were wrecked).