Luftwaffe "sanity options 2.0", 1935-43

[thaddeus]

Beer is on me if someone can provide a good source about the 1000 of Ju 86s rotting away in the depots

No, what happened was that the Ju 86 was cancelled so quickly that it left Junkers with components for a number of aircraft. There was a proposal in 1940 to finish them with petrol engines and issue them to the training units to free up the Ju 52s used in that role.

On the Ju-86, i was merely extrapolating on what NOMISYRRUC said, if there were components for 1000 planes and someone proposed during wartime to finish them as trainers/transports, that means they've been stashed in depots for a few years.
Wiki says the same thing about components left over for 1000 aircraft, sourced from a 1959 book. I know wiki isn't much though.

FWIW I got the Junkers JU 86 book by Griehl and it seems the total production was around 1,000, there was a point at which production stopped and there were airframes (a bit unclear, maybe we could say materials)

then more aircraft were built, and some work continued on the "high flyers" with a thought towards four engine version. but it seems clear there were airframes/materials for low 100's available not approaching 1,000.

 

[tomo pauk]

German guns' gordian knot an what to do about it?
Magazine/drum fed MG 17 would've been great in the Great War, but the belt-fed MG 17 made far more sense as a defensive gun for ww2; it will also make a better turret gun if/when multiple guns are required.
MG 131 was rife with shortcomings: too late to matter, and with low AP performance + low HE performance; the good qualities of high RoF, small size and low weight were not able to cancel the shortcomings. Licencing of, perhaps Italian 12.7mm can solve the bad timing issue, so a belt-fed HMG can be had for the BoB (talk, four on the Bf 109?). Making a gun around the ww1 13mm TuF round solves the low power problems, and the HMG could've been devised for that round by second half of 1930s. Later, once the ShKAS and Shvak are captured, copy their systems to achieve high or very high RoF. 13mm TuF HMG should be a very good defensive gun.
MG FF(M) - use the darned high-capacity drums from the get go, followed by belt-feed system in quick succesion (no wait until 1943 to do that).

Bigger guns:
As suggested before, 23mm Madsen is a good starting point, the gun was known well before ww2.
Operating mechanisms of the ShKAS and Shvak guns was made around the rimmed cartridges, use that to the advantage and devise a similar 25mm gun that uses French ATG bits and pieces (as an ATG it is hopeless, but the ammo is very powerful, and will come in handy as a bomber- and tank-buster) - something that is smaller and lighter than either the MK 101 or 103, so it can fit easily as a motor-cannon.
Neck-out the captured 23mm VYa cannons for the French 25mm shell, use French barrels to speed up the project.
MK 108/25 - a 250 g shell at 700 m/s, rather than a 330 g shell at 500 m/s for a much improved hit probability.

 

[Nell_Lucifer]

Maybe someone in the RLM decides they want a more powerful, longer range bullet over the standard 8 mm Mauser in 1936 and ends up with a MG131 in service by 1939?

 

[NoMommsen]

Maybe someone in the RLM decides they want a more powerful, longer range bullet over the standard 8 mm Mauser in 1936 and ends up with a MG131 in service by 1939?

... thinking of the MG 131 ... from a report by Rheinmetall-Borsig of 12.12.1939:

"The Cartridges for this device had already been tested earlier in continuous fire and brought with the same rate of fire as MG 131 normal faultless function"​

And such were the ammo mentioned

This bullet being only 0,19 mm smaller in diameter than the 'regular' MG151/15 bullet.

 

[tomo pauk]

... thinking of the MG 131 ... froma report by Rheinmetall-Borig of 12.12.1939:

Very interesting. Is the whole doc easily available?

 

[NoMommsen]

Very interesting. Is the whole doc easily available?

... tbh ... it sits on my hard drive for AAGES already together with anotherone and I have no idea where from I once obtained it.
PM me your e-mail adress an I can send it (both together are 'just' about 2.6 MB ... should be managable by some e-mail ).

 

[tomo pauk]

"The Cartridges for this device had already been tested earlier in continuous fire and brought with the same rate of fire as MG 131 normal faultless function"
And such were the ammo mentioned

This bullet being only 0,19 mm smaller in diameter than the 'regular' MG151/15 bullet.

I've taken a peek on the docs.
The 15mm 36g heavy shell was 2 grams heavier than the 13mm shell, and 10 m/s faster, 760 vs. 750 m/s. Soviet and US 12.7mm API were at 40-49g, fired at 850 to 820 m/s, depending on the projectile type.
The 15mm shell from the MG 151/15 weighted 52g, made 960 m/s when fired from the much heavier (when compared with HMGs) MG 151/15.
It is very much possible that the light 15mm shell was not bringing a worthwhile step forward vs. the MG 131.

Of note in the docs is the MG 131/08, ie. the 13mm necked down to 8mm, with 1060 m/s muzzle velocity.
In Waffen Revue there was a passage noting the MG 131/10 (late-war project), ie. the 13mm necked-down to 10 mm, 1000 m/s, for increase of AP performance (probably to deal with Allied fighters' protection for pilots?)

 

[Blue cat]

German guns' gordian knot an what to do about it?
Magazine/drum fed MG 17 would've been great in the Great War, but the belt-fed MG 17 made far more sense as a defensive gun for ww2; it will also make a better turret gun if/when multiple guns are required.
MG 131 was rife with shortcomings: too late to matter, and with low AP performance + low HE performance; the good qualities of high RoF, small size and low weight were not able to cancel the shortcomings. Licencing of, perhaps Italian 12.7mm can solve the bad timing issue, so a belt-fed HMG can be had for the BoB (talk, four on the Bf 109?). Making a gun around the ww1 13mm TuF round solves the low power problems, and the HMG could've been devised for that round by second half of 1930s. Later, once the ShKAS and Shvak are captured, copy their systems to achieve high or very high RoF. 13mm TuF HMG should be a very good defensive gun.
MG FF(M) - use the darned high-capacity drums from the get go, followed by belt-feed system in quick succesion (no wait until 1943 to do that).

Bigger guns:
As suggested before, 23mm Madsen is a good starting point, the gun was known well before ww2.
Operating mechanisms of the ShKAS and Shvak guns was made around the rimmed cartridges, use that to the advantage and devise a similar 25mm gun that uses French ATG bits and pieces (as an ATG it is hopeless, but the ammo is very powerful, and will come in handy as a bomber- and tank-buster) - something that is smaller and lighter than either the MK 101 or 103, so it can fit easily as a motor-cannon.
Neck-out the captured 23mm VYa cannons for the French 25mm shell, use French barrels to speed up the project.
MK 108/25 - a 250 g shell at 700 m/s, rather than a 330 g shell at 500 m/s for a much improved hit probability.

Not much to add other than try and accelerate the development of revolver / rotary breech cannon, and accelerate the development of the MG81.

Maybe work on gyro gun sights (perhaps with ranging radar to feed range info to the sight ?)

Not gun related but:
Maybe work on better radios for the air defence units with wider frequency ranges to make allied jamming more difficult. And on a somewhat related basis maybe put more pre war effort into to synthetic quartz production technology ? (That might help with radios and other electronic production if quartz availability wasn’t a potential bottle neck. I realize IOTL Germany was able to work around quartz shortages but perhaps that effort could have been used for other things if more quartz was available ?)

 

[Blue cat]

I've taken a peek on the docs.
The 15mm 36g heavy shell was 2 grams heavier than the 13mm shell, and 10 m/s faster, 760 vs. 750 m/s. Soviet and US 12.7mm API were at 40-49g, fired at 850 to 820 m/s, depending on the projectile type.
The 15mm shell from the MG 151/15 weighted 52g, made 960 m/s when fired from the much heavier (when compared with HMGs) MG 151/15.
It is very much possible that the light 15mm shell was not bringing a worthwhile step forward vs. the MG 131.

Of note in the docs is the MG 131/08, ie. the 13mm necked down to 8mm, with 1060 m/s muzzle velocity.
In Waffen Revue there was a passage noting the MG 131/10 (late-war project), ie. the 13mm necked-down to 10 mm, 1000 m/s, for increase of AP performance (probably to deal with Allied fighters' protection for pilots?)

I wonder if those small caliber , high velocity guns were viable against typical air craft armour without using Tungsten cored ammo ?

My understanding is that armour plate used in WW2 aircraft was often of very high quality ?

Larger calibers might be more effective without needing tungsten ?

I suppose Germany could also put more effort into stretching tungsten supplies thru better alloys for ap rounds and and / or other applications where tungsten was needed (I seem to recall the U.S. did this during ww2 ?). That being said Germany likely had more constraints on the supply of other alloying elements than the U.S. did.

 

[tomo pauk]

I wonder if those small caliber , high velocity guns were viable against typical air craft armour without using Tungsten cored ammo ?
My understanding is that armour plate used in WW2 aircraft was often of very high quality ?
Larger calibers might be more effective without needing tungsten ?

Ww2 saw the widespread service of really light 20mm cannons, including in Germany, so I too don't think that focusing much on fancy MGs is/was a way forward.

Using the time and resources to have balanced guns between 20 and 30mm makes much more sense to them. Under 'balanced', I mean that, past improving the MG FF and FFM, they need a powerful cannon type that is an easy and good fit on their small 109 and 190 fighters (neither MK 101 nor 103 were such guns, let alone the different 50 or 55mm guns they were mooting), while still having decent ballistics (MK 108 was bad in that regard).

I suppose Germany could also put more effort into stretching tungsten supplies thru better alloys for ap rounds and and / or other applications where tungsten was needed (I seem to recall the U.S. did this during ww2 ?). That being said Germany likely had more constraints on the supply of other alloying elements than the U.S. did.

'More constrains' is an euphemism here

 

[Nell_Lucifer]

I remember reading an article about the MG 151/20 and how it was described as the most successful aircraft cannon of the war, even post war it had success, ending up being used as late as the 1980s on helicopters.

 

[tomo pauk]

I remember reading an article about the MG 151/20 and how it was described as the most successful aircraft cannon of the war, even post war it had success, ending up being used as late as the 1980s on helicopters.

It was certainly a fine gun, as the wast majority of German stuff was (not to disparage other countries' engineers that also did a lot of good job back then).
From the German perspective, on their most-produced fighter, the MG 151 was a clumsy fit once more than one cannon is required, and that shortcoming was noted already when the 109F emerged. Granted, the Fw 190 was a superior platform for it.
There is also a matter of timing - the 151/20 (or any other belt-fed cannon) was not available when it was probably most needed - during the BoB. Belt-fed vs. 60 rd drum is not a merely academic question, since the later feed system allowed for just a 7 seconds of firing time, meaning that the 109E will be shortly without the ammo for their cannons, and required that 110s reload their cannons during the combat. Either way, the combat efficiency will see a drop.
The MG 151/20 was also found insufficient once the B-17s appeared above Europe in good numbers, even with Fw 190s carrying 4 of them. Germans reckoned that they need 20 of 20mm hits to down a B-17, while 4-5 30mm hits were supposed to kill a B-17 (just 1x 50-55mm hit, or 75 of 15mm hits were required for a kill of B-17, FWIW).

tl;dr - yes, an excellent gun, but with not before mid-1941, and not for the needs of LW past early 1943

 

[Nell_Lucifer]

The MG 151/20 was also found insufficient once the B-17s appeared above Europe in good numbers, even with Fw 190s carrying 4 of them. Germans reckoned that they need 20 of 20mm hits to down a B-17, while 4-5 30mm hits were supposed to kill a B-17 (just 1x 50-55mm hit, or 75 of 15mm hits were required for a kill of B-17, FWIW).

Perhaps they considered that lacking performance against bombers a good enough tradeoff for the other qualities of the 151. After all, the 30 mm is all well and good but if you can't mount more than 1 on a fighter then it's not worth it.

Also, did it really take more than 1 30 mm HE from the MK108 to down a B-17? I've seen photos and a video (spitfire wing I think?) with the result of a direct hit and it's not pretty for any aircraft's structural integrity.

 

[tomo pauk]

Perhaps they considered that lacking performance against bombers a good enough tradeoff for the other qualities of the 151. After all, the 30 mm is all well and good but if you can't mount more than 1 on a fighter then it's not worth it.

Purpose of an airborne cannon was to kill enemy bombers, at least for LW in 1943-45. If the cannon is found lacking in it's primary role, there is hardly another redeeming quality there to take advantage of.

If you can mount just one cannon in the Vee, then it should be the most powerful gun that can fit there, while still retaining ammo count, lest the is not rendered useless it the middle of a combat. It took Germans eternity to modify the big lump of metal (the MK 103) to fit as an engine cannon - for the Ta 152C, Do 335 engine-mount, and for the Bf 109K-8 - by what time Allies were at Rhine and Oder. The under-wing installation on the Fw 190s was with a too severe a recoil, and forced another drop in performance of the 190s that were already on the back foot vs. P-51s and P-47s.
Same drop of performance was experienced when Fw 190s were tried with 6 20mm guns - if you need 6 of them + two HMGs and result is not there, it points out that weapons in questions are not up to the task.
The MK 108 was all good an well if enemy was playing the ball by allowing the German fighters to close to under a hundred of meters, but Allies were not that stupid.

What was not there was an in-between weapon, that is easy to install on the Bf 109 as a main weapon, and to install 2-4 within the wings of the Fw 190As, or three on 190C/D, so the drag penalty is much reduced vs. the gondola MK 103 installation, a major increase of the punch vs. what the 109s and 190s usually used, all while without settling with the poor ballistics of the MK 108. Remove the cowl MGs ASAP, to balance out the increased weight and drag vs. the 20mm weapons.

Also, did it really take more than 1 30 mm HE from the MK108 to down a B-17?

4-5, at least the Germans say so.
Attempts towards 5-5.5cm weapons were towards having the 1-hit-to-kill weapons.

 

[mack8]

Not that knowledgeable on guns other than the basics, but could the MK-213 30mm be built earlier?And not necessarily with the very fast rpm and velocity, just derated a bit, while still being better than the MK108, and much lighter than the MK-103.

Also, how much weight increase would occur if the MG-131 is to be built around a 13,2 x 81mm shell? If the end result is not heavier than say the Berezin or the Ho-103, can it still fit in the Bf-109s nose?

 

[Nell_Lucifer]

Purpose of an airborne cannon was to kill enemy bombers, at least for LW in 1943-45. If the cannon is found lacking in it's primary role, there is hardly another redeeming quality there to take advantage of.

Not really? The reason why they went from the 8 mm MGs to the 20s was for the extended range and explosive power it had against enemy fighters. Which the MG 151/20 excelled at, more than the 12.7/.50s and later 20 mm Hispanos (plagued by problems that every year a new variant would be issued) of the Allies.

 

[tomo pauk]

Not really? The reason why they went from the 8 mm MGs to the 20s was for the extended range and explosive power it had against enemy fighters.

LW was never a fan of 8 LMG set-up.
Extended range that cannons were offering in theory was not an asset until the advent of computerized sights (some time mid-1944).

Which the MG 151/20 excelled at, more than the 12.7/.50s and later 20 mm Hispanos (plagued by problems that every year a new variant would be issued) of the Allies.

Nobody said that MG 151/20 was bad in killing fighters. It was found as not as good when it was about killing the B-17s.
As for how good/bad the 12.7mm were against the fighters, all the LW crewmen killed by 4-gun P-51B/C, including the crewmen of rocket-toting Bf 110s, will probably disagree with you. 6-8 of powerful 12.7mm were devastating against the fighters, or even against medium bombers.

Hispano predated the MG 151/20 by some two years, meaning that it was a far better weapon through these two years. British Hispano was debugged by late 1941, fired a heavier shell at higher MV than the 151/20, and at a greater RoF when Mk.V arrived.

Yes, American Hispanos were bad.

 

[ric350]

Not really? The reason why they went from the 8 mm MGs to the 20s was for the extended range and explosive power it had against enemy fighters

I’m not so sure about that. The Germans ”mine” shells consistently favored explosive charge over propellant charge (the opposite of the Hispano shell). The result was a projectile that had a poorer range/trajectory but would ruin your day if it hit you. This was just what the Germans needed vs a relatively stationary target like a heavy bomber, but not as good against a maneuvering fighter.

ric350

 

[Blue cat]

Not that knowledgeable on guns other than the basics, but could the MK-213 30mm be built earlier?And not necessarily with the very fast rpm and velocity, just derated a bit, while still being better than the MK108, and much lighter than the MK-103.

Also, how much weight increase would occur if the MG-131 is to be built around a 13,2 x 81mm shell? If the end result is not heavier than say the Berezin or the Ho-103, can it still fit in the Bf-109s nose?

IMHO if (and I believe this is a big if) Germany could have gotten a revolver / rotary breech cannon into service during ww2 (perhaps in 25 mm ?) that might have been a game changer for them (ie perhaps a motor (mounted) cannon firing 25 mm shells at 1500 rpm ?)

I suspect that would have been difficult to do during WW2.

I also wonder about possible issues due to changing enter of gravity while the gun is fired ? Maybe two wing mount guns might have been better ?

 

[Blue cat]

Purpose of an airborne cannon was to kill enemy bombers, at least for LW in 1943-45. If the cannon is found lacking in it's primary role, there is hardly another redeeming quality there to take advantage of.

If you can mount just one cannon in the Vee, then it should be the most powerful gun that can fit there, while still retaining ammo count, lest the is not rendered useless it the middle of a combat. It took Germans eternity to modify the big lump of metal (the MK 103) to fit as an engine cannon - for the Ta 152C, Do 335 engine-mount, and for the Bf 109K-8 - by what time Allies were at Rhine and Oder. The under-wing installation on the Fw 190s was with a too severe a recoil, and forced another drop in performance of the 190s that were already on the back foot vs. P-51s and P-47s.
Same drop of performance was experienced when Fw 190s were tried with 6 20mm guns - if you need 6 of them + two HMGs and result is not there, it points out that weapons in questions are not up to the task.
The MK 108 was all good an well if enemy was playing the ball by allowing the German fighters to close to under a hundred of meters, but Allies were not that stupid.

What was not there was an in-between weapon, that is easy to install on the Bf 109 as a main weapon, and to install 2-4 within the wings of the Fw 190As, or three on 190C/D, so the drag penalty is much reduced vs. the gondola MK 103 installation, a major increase of the punch vs. what the 109s and 190s usually used, all while without settling with the poor ballistics of the MK 108. Remove the cowl MGs ASAP, to balance out the increased weight and drag vs. the 20mm weapons.



4-5, at least the Germans say so.
Attempts towards 5-5.5cm weapons were towards having the 1-hit-to-kill weapons.

Yeah that seems to fit with post war accounts I seem to recall reading of U.S. bombers surviving hits from cannon shells. (I realize the bombers in question at that point were not B17’s and B24’s.)

The U.S. and Canadians also seemed content to largely skip cannon for their early post ww2 bomber interceptors in favour of rockets and missiles. (I think some F86 all weather bomber interceptors were cannon armed and there may have been some others..)

I have seen comments in at least one published work that credits the USAF with putting a lot of thought after ww2 into how to shoot down bombers and I believe it is telling that they didn’t adopt heavy (ie greater than 20mm) Cannon for their first post WW2 interceptors. That being said I believe I can understand why the Luftwaffe favored heavy cannon for anti bomber use in WW2, although one could speculate about the impact of the R4M entering service earlier.