AHC: the best possible Luftwaffe for 1940

Hey Wiking, in 2013 you posted a thread about the Jumo-222 in which you seemed to have come around to the engine, provided its development were allowed to be smoother without Milch's opposition. What are your current opinions about the prospects of that design?
 
For one thing they won't lose so many Bf110s in August in escort missions, which saves a ton of pilots and aircraft over OTL. Given that the Me109s were much more survivable against RAF SE fighters, especially the Hurricane, and may well do even better with a lighter 'fighter hunting' version of the Me109E the Luftwaffe would have a pretty serious advantage over OTL there. Perhaps the savings may be even greater if we suppose that a working wooden drop tank is available in the proposed scenario so fighters don't have to worry about turning back early and they have fewer losses than the Bf110 did IOTL in France due to being more surviveable against enemy fighters and having more fighters overall means less exhaustion for pilots flying lots of missions through May. As it was about 32% of the operational Bf110s were lost in the Western Campaign in May-June 1940.

Looking at casualty rates for the Bf110 up to and including 18th August it would appear that the Bf110 was three times more likely to be lost or suffer damage than the Bf109 (as a percentage of each aircraft type involved in combat). However 15% of those casualties were to aircraft acting in the ground attack role or other none escort role, and of the remainder 36% of casualties were on raids where the only escort was the Bf110. The Bf109 suffered a higher total loss rate as opposed to damaged than the Bf110, somewhere in the region of 75% loss rate for the 109 and 60% for the 110. So actual losses to fighters in the escort roll were roughly 61% Bf109 and 39% Bf110, 3% chance of loss for the Bf109 and 9% chance for the Bf110.

Also there was Stephen Bungay's book "Most Dangerous Enemy" which lays out a solid strategy for defeating the RAF in 1940, but requires hindsight to some degree, namely in the use of the Bf110 as fighter bombers. Actually defeating the RAF in 1940 might help create room to negotiate an end to the war, but that is of course highly speculative and would require following Bungay's plan to the letter and it going to plan (it involves commando raids on the radar stations and well as earlier and more bombing of the fighter and engine factories to cut the replacement flow of RAF fighters...the Germans actually knew where they were and bombed a number of them IOTL relatively late in the campaign and without follow up in part due to underestimating the output of the facilities).

One huge flaw in this is that statistically the Bf110 was more than twice as likely to become a casualty in the ground attack role than in the escort role, that would mean an extra 100+ Bf110 casualties in just the first month… completely unsustainable (there is another flaw, it was suggested by Bungay, but that’s just a personal gripe of mine).
 

Deleted member 1487

Looking at casualty rates for the Bf110 up to and including 18th August it would appear that the Bf110 was three times more likely to be lost or suffer damage than the Bf109 (as a percentage of each aircraft type involved in combat). However 15% of those casualties were to aircraft acting in the ground attack role or other none escort role, and of the remainder 36% of casualties were on raids where the only escort was the Bf110. The Bf109 suffered a higher total loss rate as opposed to damaged than the Bf110, somewhere in the region of 75% loss rate for the 109 and 60% for the 110. So actual losses to fighters in the escort roll were roughly 61% Bf109 and 39% Bf110, 3% chance of loss for the Bf109 and 9% chance for the Bf110.
Per your numbers (BTW where are they from?) how many missions were the Bf109s running total as compared to the 109s? I'm going to guess that the 109s were running FAR more missions than the 110s, so were more likely to get into combat in missions that were intercepted, especially as Bf110 losses were not replaced quickly, so dropped their participation rapidly which skews the stats.

One huge flaw in this is that statistically the Bf110 was more than twice as likely to become a casualty in the ground attack role than in the escort role, that would mean an extra 100+ Bf110 casualties in just the first month… completely unsustainable (there is another flaw, it was suggested by Bungay, but that’s just a personal gripe of mine).
Got some source with that stat to back that up?

Hey Wiking, in 2013 you posted a thread about the Jumo-222 in which you seemed to have come around to the engine, provided its development were allowed to be smoother without Milch's opposition. What are your current opinions about the prospects of that design?
I don't remember all the details now and would have to go muddle through a section of a German language memoir by the guy who actually ran the team that worked on the 222 for Jumo. IIRC in any event it wouldn't have been ready by 1941 when Milch gave the order to increase the power output of the engine to match the new spec demanded by the Ju288. The question is whether it would have been ready in the 2000hp range in 1942. At least one German historian (Lutz Budrass) of the RLM thinks so had it not been ordered to be increased in power, as IIRC he claims it was made workable in 1943 or so in the 2500hp range per Milch's original order, but then was ordered to increase that to 3000hp, which it was meeting in 1945 purportedly. Again IIRC the solution was using metals that Germany did not have access to in large perhaps mass production quantities per Bradner, the guy who ran the team that worked on the engine in 1940. Now I don't remember for certain and would need to go back and try and read his memoir. If you want to try and read it yourself, the link is here in a thread I started on another forum and another poster shared:
https://ww2aircraft.net/forum/threads/jumo-222-whats-the-truth.39301/page-6
It is the last post in the thread. The only issue is that it is only in German.
 
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Deleted member 1487

Like every device, it has it's pros and cons. If indeed it was lighter (and smaller) - perhaps install 2 per wing for 4 guns total?
Depends on how much lighter.

As always - API all the way for HMGs :)

I prefer a situation with greater firepower vs. a situation with lower firepower.
The HMG firing API adds armor-piercing feature to the firepower. so we might kill enemy pilot instead of have him slightly wounded by shell fragments. Also means retaining ability to fire at enemy once the 90 rd drum is emptied somewhere over Midlands.
Anthony William's "Rapid Fire" the history of autocannons covers this and the Germans found AP rounds tended to be deflected during penetration of aircraft skin so that it often deviated enough from it's path that it never even struck the armored areas. Explosive content was far more damaging even without hurting the armored areas, because it would rip the aircraft apart enough that it would stop functioning. No need to try and shoot through the armored bits to hit the pilot when the aircraft itself is falling out the sky in pieces. Also the Germans abandoned the shell fragment as a damage mechanism early on with the minengeschoss because the blast effect was more damaging, so the least amount of metal was used relative to the maximum possible HE content.
https://en.wikipedia.org/wiki/Mine_shell_(projectile)

If AP was the best the Germans would have just put a 9-11mm bullet on the 13mm cartridge and got a super penetrator with a nice long heavy bullet (the 10.75mm bullet/cartridge was in production in Germany since the 1920s, so they had the barrel making equipment, if used in the MG131 cartridge/HMG it would have been able to be made quite long and heavy and about as good as you'd get for a weapon that light. The French were testing 9-11m HMGs in the interwar settling on 9 and 11mm MGs to compare but the 1940 invasion prevented them from getting into production, but apparently they worked very well and the HK in the 1990s did develop a 9mm AT rifle along the same lines and it was just as damaging at the US .50 caliber MG round, more in fact at 1000m). But they found that was inferior to the blast effect.

So the 13mm round would be able to carry more HE than smaller bullets, all things considered, and with the belt mechanism and being lighter or at least no heavier than the MG FF, not to mention higher velocity, would allow for longer firing and though less damage at least would have more opportunity to do fatal damage. The Raufoss 12.7mm round of today operates on the same idea and in fact is remarkable like the German B Patrone in concept, though simplified and using more powerful materials.

I will not narrow down the aft part of bomb bay. You can note that 250+500 kg bombs side-a-side are narrower than 500+1000 kg.
Same as Do-217, the Ju-88A-1 and A-5 was wide enough to carry 4 rows of 50 kg bombs. Manual, especially pg. 31.
Reduced to 2 rows with A-4 and it's offsprings.
So you have a slightly smaller Do217. Much slower than the OTL Ju88 with the same engines due to being significantly larger. Why not just have Dornier start working on an enlarged Do17 in 1936, rather than the dive bombing 217 in 1938.
Going by the actual original design spec for the Do217, it really does seem like that is exactly what you want, minus the naval/dive role:
https://en.wikipedia.org/wiki/Dornier_Do_217#Development_and_design
 
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Per your numbers (BTW where are they from?) how many missions were the Bf109s running total as compared to the 109s? I'm going to guess that the 109s were running FAR more missions than the 110s, so were more likely to get into combat in missions that were intercepted, especially as Bf110 losses were not replaced quickly, so dropped their participation rapidly which skews the stats.


Got some source with that stat to back that up?
The main sources are The Battle of Britain Then and Now and the Battle of Britain Combat Archive series. I've used these to compile a list of casualties and other information in a format that makes it easier to pull out various stats as and when needed.

From 10/07/1940 to 18/08/1940 roughly 3400 Bf109 and 1100 Bf110 sorties resulted in combat.
 
Whilst the Luftwaffe wanted the Me110 did they actually need it in 1940? Could they have translated the production effort into more Me109s? After all each Me110 contains one pilot who can be 109 seated and two engines that can go to two 109s or spare one for something else.
 
Anthony William's "Rapid Fire" the history of autocannons covers this and the Germans found AP rounds tended to be deflected during penetration of aircraft skin so that it often deviated enough from it's path that it never even struck the armored areas. Explosive content was far more damaging even without hurting the armored areas, because it would rip the aircraft apart enough that it would stop functioning. No need to try and shoot through the armored bits to hit the pilot when the aircraft itself is falling out the sky in pieces. Also the Germans abandoned the shell fragment as a damage mechanism early on with the minengeschoss because the blast effect was more damaging, so the least amount of metal was used relative to the maximum possible HE content.
https://en.wikipedia.org/wiki/Mine_shell_(projectile)

No doubt that Mine shell was very effective. Pair of HMGs increases the total firepower of a fighter, while on the Bf 109E will much improve firing time, thus it is an over-all improvement. Rate of fire will be ~2200 rpm (2 MG FFM + 2 HMG) vs. ~1050 just for 2x MG FFM, thus hit probability improves, too.

If AP was the best the Germans would have just put a 9-11mm bullet on the 13mm cartridge and got a super penetrator with a nice long heavy bullet (the 10.75mm bullet/cartridge was in production in Germany since the 1920s, so they had the barrel making equipment, if used in the MG131 cartridge/HMG it would have been able to be made quite long and heavy and about as good as you'd get for a weapon that light. The French were testing 9-11m HMGs in the interwar settling on 9 and 11mm MGs to compare but the 1940 invasion prevented them from getting into production, but apparently they worked very well and the HK in the 1990s did develop a 9mm AT rifle along the same lines and it was just as damaging at the US .50 caliber MG round, more in fact at 1000m). But they found that was inferior to the blast effect.

Indeed, nothing prevents Germans to make a 'mini HVAP-I' ('or mini APCR-I') projectile for the HMG. Even the steel core will work vs. aircraft armor and BP glass. The PzB 38 and 39 used similar projectile already.

So the 13mm round would be able to carry more HE than smaller bullets, all things considered, and with the belt mechanism and being lighter or at least no heavier than the MG FF, not to mention higher velocity, would allow for longer firing and though less damage at least would have more opportunity to do fatal damage. The Raufoss 12.7mm round of today operates on the same idea and in fact is remarkable like the German B Patrone in concept, though simplified and using more powerful materials.

Raufoss 12.7 mm is API-HE - it has a penetrator, incendiary content and HE content. link

So you have a slightly smaller Do217. Much slower than the OTL Ju88 with the same engines due to being significantly larger. Why not just have Dornier start working on an enlarged Do17 in 1936, rather than the dive bombing 217 in 1938.
...

'My' Ju-88 modification does not involve enlarging it.

Whilst the Luftwaffe wanted the Me110 did they actually need it in 1940? Could they have translated the production effort into more Me109s? After all each Me110 contains one pilot who can be 109 seated and two engines that can go to two 109s or spare one for something else.

Cancel the Bf 110 in 1936 and there is enough of time and resources to invest into more Bf 109s.
 

Deleted member 1487

No doubt that Mine shell was very effective. Pair of HMGs increases the total firepower of a fighter, while on the Bf 109E will much improve firing time, thus it is an over-all improvement. Rate of fire will be ~2200 rpm (2 MG FFM + 2 HMG) vs. ~1050 just for 2x MG FFM, thus hit probability improves, too.
I don't know why you're sticking to the idea that the HMGs on the table in 1940 would be able to fit into the nose mount of the Bf109, because not only were they too big and heavy they also slowed down their ROF to levels before that of the MG FF. You're either stuck with the HMG in the motor cannon mount or just sticking with the regular MGs in the nose. And it's really funny that you're now trying to make the argument I already made about the 9mm MG 17s just with one caliber step up. 9mm MGs are much faster firing, fire at a higher velocity, and are lighter so you can fit lots of them in the Me109 for a net weight savings.

BTW in terms of the weight penalty of 10kg more, apparently the MK108 had a noticeable negative impact on the ME109K and was around 10kg heavier than the MG115/20. And that was just the one they planned to put in the motor cannon location, i.e. the center line mount rather than the wings.

Indeed, nothing prevents Germans to make a 'mini HVAP-I' ('or mini APCR-I') projectile for the HMG. Even the steel core will work vs. aircraft armor and BP glass. The PzB 38 and 39 used similar projectile already.
Except their experience that such a projectile was inferior to the HE shell.
They did try such a weapon with the MG131:
http://www.municion.org/792/7_92x81_5.htm
They just decided it wasn't worthwhile.

Raufoss 12.7 mm is API-HE - it has a penetrator, incendiary content and HE content. link
I am aware of what it is, they are just substituting the penetrator for the small steel inertia pin that pushes into the HE component that detonates the B Patrone. Honestly there is no reason the Germans couldn't have come up with something like that with the technology of the day if they weren't convinced that the minengeschoss was the pinnacle of ammo technology.

'My' Ju-88 modification does not involve enlarging it.
I don't know how you plan on cramming 500kg bombs into the space the Ju88 had for bombs then.
 
I don't know why you're sticking to the idea that the HMGs on the table in 1940 would be able to fit into the nose mount of the Bf109, because not only were they too big and heavy they also slowed down their ROF to levels before that of the MG FF. You're either stuck with the HMG in the motor cannon mount or just sticking with the regular MGs in the nose. And it's really funny that you're now trying to make the argument I already made about the 9mm MG 17s just with one caliber step up. 9mm MGs are much faster firing, fire at a higher velocity, and are lighter so you can fit lots of them in the Me109 for a net weight savings.

BTW in terms of the weight penalty of 10kg more, apparently the MK108 had a noticeable negative impact on the ME109K and was around 10kg heavier than the MG115/20. And that was just the one they planned to put in the motor cannon location, i.e. the center line mount rather than the wings.

The 109K-6 and K-10 were planned with 3x MK 108s + 2x MG131s; 109K-8 with 1x MK103M + 2x MK 108. Wing MK 108s within the slightly redesigned wing.
I have no problems RoF of Breda RoF going down to 570 rpm when synchronised, and I've never proposed the HMG as a good HE thrower, but API all the way. My money is on MTT engineers being good enough to fit two Bredas under cowling.

I am aware of what it is, they are just substituting the penetrator for the small steel inertia pin that pushes into the HE component that detonates the B Patrone. Honestly there is no reason the Germans couldn't have come up with something like that with the technology of the day if they weren't convinced that the minengeschoss was the pinnacle of ammo technology.

Raufoss retained the AP element for AP duties, their 20mm and bigger MP shells of their design don't have any striker or pin to igninte the incediary content. It is ignited when nose of the shell is crushed enough to rise temperature and pressure enough, and incendiary content then ignites explosive content. That also makes their MP ammo very safe, since even when it lands nose-first due to careless handling it will not ignite/explode, ditto for shell that didn't explode after firing.
FWIW:
link1
link2

I don't know how you plan on cramming 500kg bombs into the space the Ju88 had for bombs then.

Junkers themselves crammed 4 rows of 50kg bombs + 4 tilted racks, side-a-side, in bomb bay of Ju 88 (items 1-24 are 50kg bombs; 'Vorderer lastraum' = 'front payload space', roughly):

CR322105.jpg


Span of stabilizers of 50 kg bomb was 280mm, vs. 470mm on the 500 kg bomb. So we have two 500 kg bombs side-a-side in less than 1000mm, and 4x 50 kg bombs that require 1120 mm + space for 4 racks + distance between bomb columns.

The Scotti M1933 seems to have been 21kg, but only about 750rpm, and standard velocity for the Italian 12.7mm cartridge
https://translate.google.com/transl...war.ru/weapon/guns/scotti127.html&prev=search

Though from the above link the Scotti ultra-light 6.5mm MG sounds interesting for ground use.

Almost anything that is at 6.5mm or in the ballpark gets my vote.
 

Deleted member 1487

The 109K-6 and K-10 were planned with 3x MK 108s + 2x MG131s; 109K-8 with 1x MK103M + 2x MK 108. Wing MK 108s within the slightly redesigned wing.
I have no problems RoF of Breda RoF going down to 570 rpm when synchronised, and I've never proposed the HMG as a good HE thrower, but API all the way. My money is on MTT engineers being good enough to fit two Bredas under cowling.
Bomber killers, but total dogs in the air due to the heavy armament.
API when the muzzle velocity was so weak compared to Allied versions isn't going to be as good as HEI-T shells. I'm not sure how they could fit something so long, heavy, and large in the Bf109's nose.

Going back a bit, since our starting point is in 1936 and given that the French were already working on 9 and 11mm HMGs as intermediate anti-material HMGs I don't see why Germany couldn't have simply scaled up the MG17 to something like a 10.75mm bullet (already a caliber in production with Mauser since the early 1920s) with a larger case behind it than already in production to give it something like a 850-900m/s muzzle velocity. You'd have a high rate of fire and ability to fire API and HEI-T rounds that aren't so heavy and complex as the MG131 project and be light enough to fit a bunch of them in even a platform as light as the Bf109. The penetration of a long AP round should be excellent at 850-900m/s due to sectional density, which is why the French were looking at them as ground based anti-material weapons without going up to 13mm caliber HMGs with the weight they'd bring, while being wide enough to fit in sufficient special loads.

The Russians did something similar with a 30mm cannon:
https://en.wikipedia.org/wiki/Gryazev-Shipunov_GSh-30-1
Same recoil system and higher rate of fire, though a bit more complex due to extra features.

Raufoss retained the AP element for AP duties, their 20mm and bigger MP shells of their design don't have any striker or pin to igninte the incediary content. It is ignited when nose of the shell is crushed enough to rise temperature and pressure enough, and incendiary content then ignites explosive content. That also makes their MP ammo very safe, since even when it lands nose-first due to careless handling it will not ignite/explode, ditto for shell that didn't explode after firing.
FWIW:
link1
link2
Those Raufoss munitions were also meant to be used against armor ground targets and better armored aircraft, so they need the entire package.
Thanks for the info about the MP ammo. I wonder why no one thought of that during WW2.

Junkers themselves crammed 4 rows of 50kg bombs + 4 tilted racks, side-a-side, in bomb bay of Ju 88 (items 1-24 are 50kg bombs; 'Vorderer lastraum' = 'front payload space', roughly):

Span of stabilizers of 50 kg bomb was 280mm, vs. 470mm on the 500 kg bomb. So we have two 500 kg bombs side-a-side in less than 1000mm, and 4x 50 kg bombs that require 1120 mm + space for 4 racks + distance between bomb columns.
So per your calculations they could have already fit in the existing Ju88 bomb bay, no need to change the core design other than remove the dive requirement and ventral gondola and minor modifications to the bomb bay. The one issue could be the length of the bomb though, but perhaps they could modify the bomb tail and mount it vertically like in the He111.

Almost anything that is at 6.5mm or in the ballpark gets my vote.
For the Italians anything would be a step up compared to their squad and platoon MGs.
 
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Bomber killers, but total dogs in the air due to the heavy armament.
API when the muzzle velocity was so weak compared to Allied versions isn't going to be as good as HEI-T shells. I'm not sure how they could fit something so long, heavy, and large in the Bf109's nose.

Soviets went even further, installing the full-power, automatic 37mm cannon aboard the LaGG-3 and Yak-9.
The MK 103 required a rework to make them be able to fit as motor-cannons on Do 335, Ta 152 and Bf 109 as the MK 103M ('fuer Motor-lafette'); the Bf 109 supposed to sacrifice HMGs, too, when MK 103M was to be installed.

Going back a bit, since our starting point is in 1936 and given that the French were already working on 9 and 11mm HMGs as intermediate anti-material HMGs I don't see why Germany couldn't have simply scaled up the MG17 to something like a 10.75mm bullet (already a caliber in production with Mauser since the early 1920s) with a larger case behind it than already in production to give it something like a 850-900m/s muzzle velocity. You'd have a high rate of fire and ability to fire API and HEI-T rounds that aren't so heavy and complex as the MG131 project and be light enough to fit a bunch of them in even a platform as light as the Bf109. The penetration of a long AP round should be excellent at 850-900m/s due to sectional density, which is why the French were looking at them as ground based anti-material weapons without going up to 13mm caliber HMGs with the weight they'd bring, while being wide enough to fit in sufficient special loads.

Aynway we slice it, some form of widely-available & reliable HMG would've come in handy for LW for 1939-41.

So per your calculations they could have already fit in the existing Ju88 bomb bay, no need to change the core design other than remove the dive requirement and ventral gondola and minor modifications to the bomb bay. The one issue could be the length of the bomb though, but perhaps they could modify the bomb tail and mount it vertically like in the He111.

The vertical bomb load, like on the He-111, is an interesting idea. Limited to 250 kg bombs, but 8 of these are quite a firpower anyway.
As for the Ju 88 carrying bigger bombs internally as-is, in horizontal position, indeed they will not fit due to the length. Hence no change to core design of the bomber, but relocating the wing into a more convenient position.
 

Deleted member 1487

Soviets went even further, installing the full-power, automatic 37mm cannon aboard the LaGG-3 and Yak-9.
The MK 103 required a rework to make them be able to fit as motor-cannons on Do 335, Ta 152 and Bf 109 as the MK 103M ('fuer Motor-lafette'); the Bf 109 supposed to sacrifice HMGs, too, when MK 103M was to be installed.
I thought the MK103M for the K-series was just a proposal without anyone actually knowing if it would work or even getting around to try it.

Aynway we slice it, some form of widely-available & reliable HMG would've come in handy for LW for 1939-41.
Not just any HMG though especially if you're interested in API ammo. Best of course would be some sort of 20mm cannon that could fit in the motor cannon position....
Actually come to think of it shouldn't the Breda-SAFAT have been able to be necked up to 15mm? It was too narrow for a 20mm round unfortunately, but if the Germans developed 15mm minengeschoss it would be pretty perfect for the motor cannon mount.
The HEI-T rounds would deal solid damage:
http://www.municion.org/15/TallatG.jpg
Even with the weight in the wings it might have been pretty good for the Bf109E to have 3x Breda 12.7/15mm HMGs. All would be belt fed, the trajectory wouldn't be much worse than the 20mm MG FF. The rounds were about 52g while the standard 12.7mm bullets were about 37.5g, so that might suck...but even something around 14mm would be significantly lighter, but pack a significantly bigger punch than the 12.7mm rounds especially if there were 3 of them and the MG17s could be deleted.
Edit:
The 13.9mm Boys AT rifle had a 47.6g AP bullet, so having a 14mm HEI bullet would probably be even lighter, so not too heavy as the 15mm HEI projectile would be.

The vertical bomb load, like on the He-111, is an interesting idea. Limited to 250 kg bombs, but 8 of these are quite a firpower anyway.
As for the Ju 88 carrying bigger bombs internally as-is, in horizontal position, indeed they will not fit due to the length. Hence no change to core design of the bomber, but relocating the wing into a more convenient position.
Vertical storage would mean no need to change the wing position. The only difference would probably be the need to change out the type of bomb racks depending on the mission.
 
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Not just any HMG though especially if you're interested in API ammo. Best of course would be some sort of 20mm cannon that could fit in the motor cannon position....

MG FFM was carried on the Bf 109F0s as motor cannon, previous attempts for such weapon layout were hampered until the whole set-up was suitably modified to work reliably.

Actually come to think of it shouldn't the Breda-SAFAT have been able to be necked up to 15mm? It was too narrow for a 20mm round unfortunately, but if the Germans developed 15mm minengeschoss it would be pretty perfect for the motor cannon mount.
The HEI-T rounds would deal solid damage:
http://www.municion.org/15/TallatG.jpg
Even with the weight in the wings it might have been pretty good for the Bf109E to have 3x Breda 12.7/15mm HMGs. All would be belt fed, the trajectory wouldn't be much worse than the 20mm MG FF. The rounds were about 52g while the standard 12.7mm bullets were about 37.5g, so that might suck...but even something around 14mm would be significantly lighter, but pack a significantly bigger punch than the 12.7mm rounds especially if there were 3 of them and the MG17s could be deleted.
Edit:
The 13.9mm Boys AT rifle had a 47.6g AP bullet, so having a 14mm HEI bullet would probably be even lighter, so not too heavy as the 15mm HEI projectile would be.

Something like this maybe:

For ze Germans:
- "MG 141" - a 15mm cannon, firing both HE and API, belt-fed, electric primed, firing from closed bolt, 800+ rpm, 750 m/s, ~25 kg, for defensive positions, as well as synchronised for fighters
...
...that is obvoiously a clean-sheet design.

But, yes, a 'Breda 15mm cannon' I do like. Can be synchronised, belt-fed, will not be of too big size nor weight, and has favorable timing.


Vertical storage would mean no need to change the wing position. The only difference would probably be the need to change out the type of bomb racks depending on the mission.

My only negative remark for vertical bomb storage will be that it will not carry anything above 250 kg. But then again, a Ju 88 with 2000 kg of 250 kg bombs carried internally is much closer to the fast bomber idea than it was the case with OTL Ju-88A1 and on.
 

Deleted member 1487

MG FFM was carried on the Bf 109F0s as motor cannon, previous attempts for such weapon layout were hampered until the whole set-up was suitably modified to work reliably.
Not sure that ever saw service. The problem was the MG FF barrel was too large to fit in the space available through the engine due the recoil system. So the issue wasn't that any weapon couldn't work in the E-series, just that the MG FF couldn't due to it's size.

Something like this maybe:

...that is obvoiously a clean-sheet design.

But, yes, a 'Breda 15mm cannon' I do like. Can be synchronised, belt-fed, will not be of too big size nor weight, and has favorable timing.
Probably would run into the developmental delays of the MG131, so not ready in time for 1940. I don't see why such a system couldn't work out later though, but without actually sitting in a space that would require synchronization with the prop it didn't need to be electrically primed. 15mm is probably too heavy for the 12.7mm cartridge without a minengeschoss shell (lighter weight due to the filler being so light relative to other loads, especially AP). 14mm is probably the max to get a shell light enough to have at least 700m/s muzzle velocity with the Italian 12.7mm cartridge.

Edit:
Never mind. The German 13mm projectile is actually 13mm and a step up in size over the Italian projectile, while still being slightly lighter for the HEI-T round. So the German 13mm projectile on the Italian cartridge would be even faster out the muzzle than the Italian bullet, while carrying more than double the filling of the Italian projectile (Italian round has a total filling of 0.8g PETN, the German 1.4g PETN+.3g thermite). So 3x Scotti 12.7/13mm HMGs would be a very lethal firepower package for a fighter in 1940 and beyond, which a net weight savings vs. the MG FF plus with the added benefit of belt feeding and probably no need for bulges in the wings to make room for drums.

They could be even more lethal if they actually made a minengeschoss in 13mm. The Soviets made one in 12.7mm:
https://forum.il2sturmovik.com/topic/25294-breda-vs-berezin/
bAov7p.png

The MD-46 and MDZ-46 bullets were high explosive bullet designs from early WWII and a number of specimens from that time exist. Inside the gilding metal clad steel envelope a steel body filled with high explosive is located. The MDZ-46 bullet differs from the MD-46 in having an additional incendiary filler below the high explosive payload. The high explosive incendiary bullet MDZ-3 ignites gasoline in unprotected fuel tanks only. When fired into a duralumin aircraft wing, the MDZ-3 bullet creates an entrance opening with a diameter of approximately 20mm and an exit opening of up to 110mm diameter. The modern MDZ bullet defeats a 2.0mm duralumin sheet at a range of up to 1,500m.

My only negative remark for vertical bomb storage will be that it will not carry anything above 250 kg. But then again, a Ju 88 with 2000 kg of 250 kg bombs carried internally is much closer to the fast bomber idea than it was the case with OTL Ju-88A1 and on.
Why the limit? I thought that was only due to a choice not to swap out carriers for the larger, heavier bombs. Honestly given the space I don't see why 4 couldn't be carried in the space available provided the dimensions with the carriage fit and the set up is rated to take that much weight. I'm not sure that the space would be wide enough for 8 vertical 250kg racks, but if someone can get the dimensions of both the Ju88 bays and HE111s we can figure it out.
 
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Also I finally got my hands on a copy of the Fw187 book:
https://www.amazon.com/Focke-Wulf-F...ie=UTF8&qid=1550709847&sr=8-1&keywords=fw+187

There are a number of figures for the performance of the Fw187 without evaporative cooling and with DB engines though they did not seem to have flown with them, the prototypes and pre-production versions of them were cancelled before they flew. They apparently were able to calculate them based on the performance of the A-0 preproduction versions and the various figures for the performance of the DB engines and weight increases they would need. So while not 100% accurate to reality, they were close enough to be taken as pretty representative of what could be expected from the design, as the actual aircraft had flown, just not with as powerful of engines. It seems to bear up to what the fanboys expect of it. When I can I'll scan some of the documents in the book and post them. In 1940 with DB601N engines the major performance increases over the Bf109 would justify their manufacture even with the cost of losing extra engines.

There however was testing done with the FW187 V5 prototype with DB601 engines (it had been designed around them in the first place, but was adapted to the weaker Jumo 210 engine) and clocked a max of 635 km/hr at low levels (i.e. not at altitude where it would be fastest), which for us Americans is almost 395 mph. However that was with the evaporative surface cooling system, not normal radiators. To compare with the Jumo 210 equipped test model the FW187 V4 had a max of 515 km/hr at 1900m, but 545 km/hr at 4600km. Applied to the V5 with the Daimler engines that would mean top speed could be closer to 670 km/hr at altitude (probably around 5000m) or 416mph. Of course since that is without the drag from normal radiators that probably would be dropped by at least 10mph. So the Daimler powered FW187 A-0 would likely be able to achieve 400mph at altitude. In 1940 the Spitfire I with 100 octane fuel and full boost power at altitude was only achieving 367mph for 5 minutes. That sort of speed advantage would be devastating. That is more than the advantage the P-51D had over the Me109G14 in 1944.
 
Also I finally got my hands on a copy of the Fw187 book:
https://www.amazon.com/Focke-Wulf-F...ie=UTF8&qid=1550709847&sr=8-1&keywords=fw+187

There are a number of figures for the performance of the Fw187 without evaporative cooling and with DB engines though they did not seem to have flown with them, the prototypes and pre-production versions of them were cancelled before they flew. They apparently were able to calculate them based on the performance of the A-0 preproduction versions and the various figures for the performance of the DB engines and weight increases they would need. So while not 100% accurate to reality, they were close enough to be taken as pretty representative of what could be expected from the design, as the actual aircraft had flown, just not with as powerful of engines. It seems to bear up to what the fanboys expect of it. When I can I'll scan some of the documents in the book and post them. In 1940 with DB601N engines the major performance increases over the Bf109 would justify their manufacture even with the cost of losing extra engines.

I'm glad tat you've gotten the book, and look forward to see some scans from it, hopefully the facsimiles of test reports.
Re. DB 601N - that will also give extra performance to the Bf 109Es and He 100s.

There however was testing done with the FW187 V5 prototype with DB601 engines (it had been designed around them in the first place, but was adapted to the weaker Jumo 210 engine) and clocked a max of 635 km/hr at low levels (i.e. not at altitude where it would be fastest), which for us Americans is almost 395 mph. However that was with the evaporative surface cooling system, not normal radiators. To compare with the Jumo 210 equipped test model the FW187 V4 had a max of 515 km/hr at 1900m, but 545 km/hr at 4600km. Applied to the V5 with the Daimler engines that would mean top speed could be closer to 670 km/hr at altitude (probably around 5000m) or 416mph. Of course since that is without the drag from normal radiators that probably would be dropped by at least 10mph. So the Daimler powered FW187 A-0 would likely be able to achieve 400mph at altitude. In 1940 the Spitfire I with 100 octane fuel and full boost power at altitude was only achieving 367mph for 5 minutes. That sort of speed advantage would be devastating. That is more than the advantage the P-51D had over the Me109G14 in 1944.

Several remarks for the speed figure, and expected performance loss for a service-worthy aircraft.
We have Fw 190A-5 in over-boost (1900-2000 HP) making less than 600 km/h under 2.7 km. Fw 190D-9 with MW 50 (= ~2000 HP) doing 600 km/h at 1 km. Bf 109K-4 does 580 km/h at SL on 1800 HP. Tempest V with 2100 HP, less than 400 mph at 1km. P-51B using 1830 HP (150 grade fuel) doing 368 mph at 1.3 km. These aircraft have advantage of lower weight and/or smaller size (especialy German fighters), some of them with very good/excellent cooling system. None has extra drag provided by engines in nacelles.
All said, the figure of almost 400 mph at low level for the Daimlerized Fw 187 requires a truckload of salt to digest, even if the said 187 is outfitted with evaporative cooling.
For a real-world example of a compact fighter (wing was even smaller than on the Jumo Fw 187s) powered by two DB 601As, in service outfit, we can take a look at IMAM Ro.58 - 378 mph clocked with 3 cannons and rear gunner.
 
Not sure that ever saw service. The problem was the MG FF barrel was too large to fit in the space available through the engine due the recoil system. So the issue wasn't that any weapon couldn't work in the E-series, just that the MG FF couldn't due to it's size.

Not just that it was fitted as engine-cannon on Bf 109F0s, it was also specified as wepon on He 100D. People at Dornier went one step ahead, offering even bigger Oerlikon FFS as engine-cannons(!) on Do 215.

Probably would run into the developmental delays of the MG131, so not ready in time for 1940. I don't see why such a system couldn't work out later though, but without actually sitting in a space that would require synchronization with the prop it didn't need to be electrically primed. 15mm is probably too heavy for the 12.7mm cartridge without a minengeschoss shell (lighter weight due to the filler being so light relative to other loads, especially AP). 14mm is probably the max to get a shell light enough to have at least 700m/s muzzle velocity with the Italian 12.7mm cartridge.

I've proposed the 'MG 141' as a clean-sheet design. The weak-ish ~.50 in cartriges (Italian or MG 131) will not work well, or at all as base, probably the best bet is to neck-out the 13mm TuF of ww1 vintage for Germans. French 13.2mm or US .50 BMG might also work, those two were powerful.
Granted, the 'MG 141' will be too late for 1939/40, unless Germans axe both MG 131 and 151 early on and concentrate on the 141.

Why the limit? I thought that was only due to a choice not to swap out carriers for the larger, heavier bombs. Honestly given the space I don't see why 4 couldn't be carried in the space available provided the dimensions with the carriage fit and the set up is rated to take that much weight. I'm not sure that the space would be wide enough for 8 vertical 250kg racks, but if someone can get the dimensions of both the Ju88 bays and HE111s we can figure it out.

The 500 kg bombs were long, at 2000+mm, vs. ~1650 mm for 250 kg.
I' can't find any lead towards a He 111 carrying anything in vertical rack other than 250 kg bombs. But never the less, and even with 250 kg bombs only, me likes the Ju-88 + vertical bomb storage.
 
Bomber killers, but total dogs in the air due to the heavy armament.
API when the muzzle velocity was so weak compared to Allied versions isn't going to be as good as HEI-T shells. I'm not sure how they could fit something so long, heavy, and large in the Bf109's nose.
Soviets went even further, installing the full-power, automatic 37mm cannon aboard the LaGG-3 and Yak-9.
And the Soviets installed necked-out 45 mm NS-45 cannons and experimented with 57 mm cannons in the Yak-9s propeller hub. The 57 mm cannons were not successful because the barrel was too short to extend past the cylinder banks, so the muzzle blast essentially destroyed the engine.

Going back a bit, since our starting point is in 1936 and given that the French were already working on 9 and 11mm HMGs as intermediate anti-material HMGs I don't see why Germany couldn't have simply scaled up the MG17 to something like a 10.75mm bullet (already a caliber in production with Mauser since the early 1920s) with a larger case behind it than already in production to give it something like a 850-900m/s muzzle velocity. You'd have a high rate of fire and ability to fire API and HEI-T rounds that aren't so heavy and complex as the MG131 project and be light enough to fit a bunch of them in even a platform as light as the Bf109. The penetration of a long AP round should be excellent at 850-900m/s due to sectional density, which is why the French were looking at them as ground based anti-material weapons without going up to 13mm caliber HMGs with the weight they'd bring, while being wide enough to fit in sufficient special loads.
That would work, but it should be noted that the MG131 was already close to a scaled-up MG17. It was designed by Louis Stange like the MG30 (the basis for the MG15, MG17, MG81, and MG34), used the Solothurn Lock like the MG30 family did, and in general had similar design. Details were different, though, with electrical firing and other minor differences.

One other thing that should be noted in general is that a gun's rate of fire will slow somewhat as the gun's mechanism is scaled up. The power of the recoil (or gas piston) increases due to a heavier shell, and this greater power should drive the mechanism at a higher speed, but it is more than canceled out by the other increases. The size and mass of both the cartridge and bolt increase, requiring more force to move them at a given speed, and since the cartridge is longer, it will have to move back and forward a greater distance to eject and reload the rounds. Both of these mean that gun rate of fire tends to decrease as a mechanism is scaled up, even though the Q factor usually remains the same at a given muzzle velocity (it is after all a measurement of the inherent mechanism of the gun, not its size). On the WWII aircraft gun chart, it can be seen that guns of a given family have decreasing rates of fire as the cartridge power increases. The most prolific gun family on the chart is the Browning, with the .30 M2 and .303 having 1150-1200 rpm, the Ho-103 having 800-900 rpm, the .50 M2 and Ho-5 having 750-850 rpm, the Ho-155 having 400 and then 500 rpm, and the Ho-204 having 300-400 rpm. These all used the same basic mechanism. The same can be seen with the Oerlikon family (including the MG FF and 20 mm Type 2), the Berlin UB and B-20, the ShKAS and ShVAK, the NS-37/45 and NS-23, etc.

For this reason the challenge for aircraft gun (and antiaircraft gun) designers is to build a mechanism with the maximum possible Q factor. In other words, a mechanism that can handle large rounds with high muzzle energy and still cycle them quickly (high rate of fire) for little weight.
The Russians did something similar with a 30mm cannon:
https://en.wikipedia.org/wiki/Gryazev-Shipunov_GSh-30-1
Same recoil system and higher rate of fire, though a bit more complex due to extra features.
In principle of operation yes, they're both short recoil, but the mechanism is very different, and actually simpler than many WWII aircraft cannons. The specific design of that mechanism is what gives the cannon its very high rate of fire for a linear action gun of that power.
 
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