MK108 impact on ground targets?

[Kryten]

What are you basing that on?

seeing 30mm RARDEN actually hit less than half an inch of armour plate and fail to breach it!

and yet the 30mm apds went straight through both sides!

If you have no real life experience of this kind of weapon you probably think it's some kind of hugely destructive monster gun based on TV and games, in reality 30mm is quite underwhelming blast wise, it's the fragments that cause the real damage to unarmoured targets-


View: https://www.youtube.com/watch?v=wewaCdSW4yc

Bear in mind what your seeing there is modern high tech 40MM ammo, not WW2 primitive stuff!

 

[Shortround6]

I believe the the HE payload of the 40mm shell in the video is 120 grams of Octol.

 

[GrauGeist]

For being "primitive", the 30mm round was about the deadliest airborn threat to anything with wings.


View: https://www.youtube.com/watch?v=ZoLLDi-M3fk

You can be sure that against soft targets on the ground: parked aircraft, vehicles, boats, structures or personnel, it will be devastating.

Against hard targets, such as medium/heavy tanks (for which it was not designed), it would make superficial damage but unlikely to breach the armor because, again, the 30mm minengeschoss round was not designed for anti-armor, but air-to-air engagement.

 

[Koopernic]

I believe the Mk 108 30mm gun was actually quite good at getting a mobility kill. One Me 262 pilot (I'm sorry I can't remember but he was interviewed by a US museum curator) said he hosed the rear deck of tanks where the intake louvers for cooling the engine were. This is a big target. I can well imagine the blast, concussion and incendiary effect damaging an engine or at least bursting a radiator hose. In addition running gear, tracks, optics and external gun mounts could be damaged. A lot of tank kills probably were just mobility kills. It may have been quite good at this.

 

[Kryten]

I believe the Mk 108 30mm gun was actually quite good at getting a mobility kill. One Me 262 pilot (I'm sorry I can't remember but he was interviewed by a US museum curator) said he hosed the rear deck of tanks where the intake louvers for cooling the engine were. This is a big target. I can well imagine the blast, concussion and incendiary effect damaging an engine or at least bursting a radiator hose. In addition running gear, tracks, optics and external gun mounts could be damaged. A lot of tank kills probably were just mobility kills. It may have been quite good at this.

So how could they confirm the "mobility kill"? did the 262 stick around to check if anyone bailed out, or did he make a pass and get the hell out, did he hit the tank, compare the tank claims in Normandy to the real toll on vehicles and it all gets a bit doubtful.

These kind of anecdotes really are dubious and likely just that, anecdotes.

 

[Shortround6]

The German mine shell was certainly an interesting idea and extremely effective in certain circumstances. The Video of the Spitfire wing hit being an almost ideal target situation for the mine shell. A lot (comparatively) of explosive inside a small confined area/volume where the pressure from the blast can blow the skin panels from the framework and bend/distort ribs. A mine shell exploding in a much larger space (fuselage of 4 engine bomber) might not show quite the damage to both sides o(or both top and bottom). The Shells are still very dangerous.
The Germans may have been the only ones who could make it in quantity during WW II.
However nobody has copied it for any purpose in the last 70 years which may tell us something also.
A lot of ground guns have gone to dual feeds allowing the gunner to change types of ammo in 1-2 seconds (one belt of AP and 2nd of HE for example) and still nobody is using the HE mine shell.

 

[wiking85]

However nobody has copied it for any purpose in the last 70 years which may tell us something also.
A lot of ground guns have gone to dual feeds allowing the gunner to change types of ammo in 1-2 seconds (one belt of AP and 2nd of HE for example) and still nobody is using the HE mine shell.

Because technology advanced past it?

 

[GrauGeist]

Because technology advanced past it?

Because an ATA missile can achieve much better results at distances far greater than 690 meters...

 

[Shortround6]

The German Mine shell was intended for use against aircraft and for that it worked well. It is debatable as to wither it was the best for that use or not, but it was a close race. It was certainly not the best for a number of other uses, anti tank or anti armor being one such use. With a large variety of targets that need to be dealt with you either put 3-4 different types of ammo in one belt hoping that 1/4 to 1/3 of the "proper shells' fired will be enough or you use general purpose shells that are not ideal for any one target but have moderately good results on most targets.
Normal HE shells with thicker body walls and less HE throw more and larger fragments and have at least some effect at longer distances from the point of burst. Some countries (users) considered this an advantage, especially for troops in the open or behind light cover. It also allowed near misses (shell hits several feet away from vehicle/parked plane/small boat to at least damage the target with fragments. Nowhere near as good as the 40mm shell in the video but sort of the same effect on a reduced scale. The Mine shell was mostly blast with smaller fragments.

 

[GrauGeist]

In all honesty, I think the closest to the Mk108 in use today, would be the GAU-8. This is not to say there is similarities between the two weapons, but the 30mm ordnance would be the link. The two main types of ammunition used in the GAU-8 (and varients) is:
PGU-14/B - Armor Piercing Incendiary (API - depleted Uranium)
PGU-13/B - High explosive incendiary (HEI)

It is the PGU-13 that would follow in the footsteps of the Minengeschoss round, as the characteristics and applications would be the very close.

Also, a close cousin to the Mk108, would be the mechanical version of the Mk103, the Mk101. In this 30mm weapon, there was a wide variety of ammunition available, including an AP round that was very capable of penetrating heavy armor. The drawback to the Mk101, was it's weight and slow RoF.

 

[Shortround6]

Actually the closest equivalent to the MK 108 is the M230 chain gun used in helicopters.

The 30 X 113B ammo (3rd from right) is the closest equivalent to the 30 X 90 RB ammo (2nd from left) of the MK 108.

It uses a lighter projectile at a higher velocity.

The 30 X 173 ammo used in the GUA-8 (3rd from right)is the modern equivalent of the 30 X 184 B ammo (1st on left in first picture) used in the MK 101/103

Photos from Tony Williams website: CANNON, MACHINE GUNS AND AMMUNITION

 

[GrauGeist]

I suppose I should have clarified that I was speaking in terms of destructive yeild

But good comparison in terms of relative size. I always wanted a collection like Tony's

 

[Kryten]

I recall the DEFA and ADEN cannons were developments of the late war mauser rotary cannon, they initially used 30mm mine shells but in testing were found to be less effective than a heavier shell with higher velocity and more fragmentation, so the mine shell concept was dropped in favour of a lower filler capacity but greater fragmentation!

It would seem the mine shell was in reality a dead end and post war scientific testing discovered it's flaws, modern HE cannon shells are all about the fragmentation pattern and density, and far more effective than the mine shell concept.

 

[wiking85]

I recall the DEFA and ADEN cannons were developments of the late war mauser rotary cannon, they initially used 30mm mine shells but in testing were found to be less effective than a heavier shell with higher velocity and more fragmentation, so the mine shell concept was dropped in favour of a lower filler capacity but greater fragmentation!

It would seem the mine shell was in reality a dead end and post war scientific testing discovered it's flaws, modern HE cannon shells are all about the fragmentation pattern and density, and far more effective than the mine shell concept.

More effective for what?

 

[Kryten]

More effective for what?

destroying aircraft.

Did you notice the Bofors video was quick to point out the fragmentation effect and it's lethal radius, blast alone has a very limited radius , if the mine shells had been replaced with the kind of fragmentation shells used today the mk108 and it's smaller brethren would have been more effective.

 

[Shortround6]

To be fair the 40mm Bofors round uses a proximity fuse and the fuse and fragments turn what would be a miss with a contact fuse into a hit. I am not sure if anybody has managed to get proximity fuses down to the 30mm size.

The early post war French and British revolver cannon used shorter cases and lower velocity but the low velocity was problem with getting hits. In addition to needing a high starting velocity you also need to retain velocity and light for their size (or frontal area) shells do not do this well. You can only trade shape (pointy nose) vs weight so much and long pointy noses may exceed the cartridge overall length the feed mechanism or gun mechanism allows.

 

[Kryten]

I seem to recall ricochet was a major problem with the lighter rounds?

 

[Koopernic]

Were there any attempts at shaped charge 30 mm mine shell developments during the war?

One would expect they would be very effective, with a penetration equal to around the 30mm shells diameter. The shaped charges used in fracking are tiny yet they blow through a pipe and a meter of rock (the 'holed'razor sharp) these holes are then used for pumping through special polymer lubricated sands to fracture through around another 150ft.

The Germans developed a number of shaped charges for use on 75mm, 88mm and 105mm artillery. The main purpose seems to have been to give their low velocity indirect fire artillery and anti tank capability (including the recoilless canon they developed for their paratroopers) the "B" versions got to penetrations of around 1 diameter while the more advanced C versions close to 1.5 diameters from about 1943/44 onwards. Rounds had names such as:
Panzergranate 38 HL/B (PzGr. 38 HL/B) or Panzergranate 38 HL/C (PzGr. 38 HL/C) The HL stood for Hol Ladung or hollow charge.

The sleeve of these rounds was on a rotating bearing to reduce projectile spin as spin induces a centrifugal effect that reduces charge effectiveness so there may have been a loss in accuracy. A 30mm round might have good penetration though one wonders about its lethality, still it would be no fun if it went through the armour you were sitting next to.

Surprisingly these round were issued to high velocity guns, including those of the Tiger I and II.

These rounds were cost effective for short range engagements requiring less metal or propellant. It was German Army policy to keep firing into a tank till it was on fire and beyond recovery and repair and perhaps they were used for this.

 

[Koopernic]

So how could they confirm the "mobility kill"? did the 262 stick around to check if anyone bailed out, or did he make a pass and get the hell out, did he hit the tank, compare the tank claims in Normandy to the real toll on vehicles and it all gets a bit doubtful.

These kind of anecdotes really are dubious and likely just that, anecdotes.

If the tank was on fire or smoking, that was an indication.

A British video of a single 30mm MK 103 mine shell test hit in a Spitfire wing at around the flap/aileron junctions shows the following effect:
The flap is blown off, the rear spar severed and a man sized hole has ripped up all the way to the main spar. In flight the wing would have failed.

A picture of a test against a Blenheim tail shows the tail blown open like a split watermelon to twice its size.

The concussive effects in the cooling intakes of a tank sure must have been signifcant and I can well imagine radiators split, fuel lines ripped, cooling lines destroyed.
The damage was likely repairable but the tank was stopped and that was often all that was needed.

Modern 'fragmentation' round often contain exotic technologies such as tungsten cubes.

Tank kill claims are likely exaggerations or really just mobility kills. The tank kill stats at Normandy show that getting a hit with a rocket was rare, very rare in combat but one can imagine the MK 108 being considerably more accurate and yet despite is low lethality if it did succeed in a hit since it was likely it could gain more hits it may have been quite effective if fired at the rear deck. It may have been more effective against thin skinned armoured vehicles such as half tracks than a rocket.

If used against thin skinned vehicles such as transports, tankers and repair vehicles the Mk 108 may have been an effective ground attack weapon. They were used to strafe and I have read of accounts of jeeps being attacked.

 

[Koopernic]

To be fair the 40mm Bofors round uses a proximity fuse and the fuse and fragments turn what would be a miss with a contact fuse into a hit. I am not sure if anybody has managed to get proximity fuses down to the 30mm size.

The early post war French and British revolver cannon used shorter cases and lower velocity but the low velocity was problem with getting hits. In addition to needing a high starting velocity you also need to retain velocity and light for their size (or frontal area) shells do not do this well. You can only trade shape (pointy nose) vs weight so much and long pointy noses may exceed the cartridge overall length the feed mechanism or gun mechanism allows.

There is no problems with 'radar on a chip' so a 0.5 calibre round could have a radar proximity fuze. However the technique used by Oerlikon Contraves for its 35mm guns (now part of or rather back into the Rheinmetall fold) is to have a muzzle velocity measuring device and then to program the fuse with a time based on muzzle velocity measurement as it exits. The fragmentation pattern is sprayed forward by shaped charge and consists of small tungsten cubes which penetrate any missile. Guns are now more for terminal defence.

Not appreciated was that the Mk 108 gun and the mine round was very cost effective. Not only were only 3-4 hits required the round itself used very little metal (a high energy content material compared to explosives because of the refining and smelting costs) furthermore the casing was easy to make from sheet stock (probably cold drawn) and finally it could carry a self destruct to limit damage to the population down below.