# Why does the German Army like 20mm auto cannons so much?



## davebender (Oct 1, 2011)

More specifically, why does the German Army like the 20mm x 138mmB / 20mm x 139mm cartridge so well? They have used it in a wide variety of weapons from the 1930s right up to the present day. Not that I have anything against this cartridge but why do they prefer it over readily available auto cannon cartridges that are more powerful?

*Panzer II ausf C. Mass produced 1937 to 1940.*
Historically armed with KwK30 or KwK38 auto cannon chambered for the 20mm x 138mmB cartridge. Not a bad light tank but why wasn’t it armed with the much more powerful 3cm Mk101 / Mk103 auto cannon? 
Armor Penetration.
49mm @100 meters. 20mm x 138mmB cartridge. Same for KwK30 and KwK38.
75mm @ 300 meters. 30mm x 184mmB cartridge. Mk101 cannon. 
70mm @ 300 meters. 30mm x 184mmB cartridge. Mk103 cannon.

*RH202 auto cannon. 20mm x 139mm cartridge.*
Main gun for Marder IFV, Luchs recon vehicle, various flak mounts etc.

The RH202 is ok but what happened to the 30mm MG213C revolver cannon that was operating in prototype during 1945? Britain copied this weapon as the ADEN cannon and it has been very successful for dozens of nations. The MG213C has a more powerful round, a higher rate of fire and yet the weapon weighs only 87kg. What’s not to like? Germany created a fantastic 30mm weapon yet the Heer chose to stick with a slightly improved version of their WWII era 20mm cartridge right into the 1980s.


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## Shortround6 (Oct 1, 2011)

1.Because the MK 101 didn't exist when the 20mm x 138B cartridge was adopted. 
2. The 30mm guns were bigger and heavier, the MK101 was almost three times heavier than the 20mm guns. 
3. Size and weight of the ammo. The MK II tank carried about 180 rounds of 20mm ammo in 18 ten round magazines. It used a one man turret ( many descriptions are wrong). while tanks are not really weight sensitive they are very volume sensitive. MK 101 could be feed with 6 round boxes but given the size of the ammo the magazines are going to be bigger and heavier and harder to change, gun breech takes up more room in the turret. Using a belt feed means you cannot change the type of ammo from AP to HE or from normal AP to an APCR or APDS round. 

RH202 auto cannon. 20mm x 139mm cartridge.

In standard loading's the older round had about 47,000 joules of muzzle energy, the new round has 72,600 joules for the HE round and 84,000 joules for the AP. A bit more than a "slight" improvement. The 20mm round for the MG213C had a muzzle energy of 61,700 joules. The rate of fire for RH202 is 800-1000rpm vs the 1200-1400rpm of the WW II gun. Without a 350-700mph slipstream of cooling air for the gun barrel high rates of fire from a single barrel can be a real problem. The New gun incorporates a dual feed. Two belts go into the feed mechanism and the gunner can select which belt (type of ammo) in 1-2 seconds. This is harder to do with a revolver cannon.


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## davebender (Oct 2, 2011)

*1935.*
3cm MG101 developed by Rheinmetall-Borsig. It was evolved from an existing 20mm AT weapon.
…..Note. MG101 was original weapon designation and used through 1940.

*1937 to 1940.*
1,113 Panzer II ausf C produced.
…..Assumption. MG101 cannon not yet production ready.
…..Point of Departure. The Panzer II turret will be designed for the 3cm MG101 cannon. The 2cm cannon will be employed as an interim weapon just as the 3.7cm cannon was employed as an interim weapon on the Panzer III. Consequently the Panzer II turret (including ammo storage) is sized to fit the larger weapon. Heer 8 wheel armored cars (Sd.Kfz 232, 233 and 234) will also use this turret.

*July 1939.*
MG101 cannon tested in Me-110B aircraft. 10 round magazine.
…..Assumption. MG101 cannon production ready NLT this date. Might have been made production ready sooner but that would be speculation.
Historical Luftwaffe procurement of MG101 cannon was tiny. The Heer will fund procurement of 200 weapons per month from fall 1939 onward. Hence this cannon will become a Heer program. 

*September 1939.*
German invasion of Poland. 16mm armor on early war Panzer IIs proved vulnerable to Polish AT rifles. Consequently frontal protection of existing vehicles was improved by adding 20mm armor plates. New production Panzer II had 30mm frontal armor built in.
…..In this scenario existing Panzer II are rearmed with the 3cm MG101 cannon while at depot for the armor upgrade.


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## Shortround6 (Oct 2, 2011)

And this gets you what when the T-34s and KVs show up? 

If you can stuff a MG101 in the turret you could probably stuff in the regular 37mm tank cannon. 
You need a bigger turret ring anyway.


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## davebender (Oct 2, 2011)

32 ton T34s and Sherman tanks don't become a serious problem until 1942. Until then most armored vehicles weighed less then 20 tons and were armed with a 37mm or 45mm main gun. Threats the dirt cheap Panzer II can handle if armed with something more powerful then the historical 20mm cannon.

The 10 ton Panzer II could probably be armed with a 3.7cm/45 main gun. Personally I think the 3cm MG101 auto cannon is a superior overall weapon. Multiple hits in close proximity allow you to chew through armor. You cannot do that with a single shot weapon.


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## tomo pauk (Oct 3, 2011)

If we really want a tank for Heer, wielding the 3cm autocannon, perhaps Pz-38(t) is better choice?


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## Shortround6 (Oct 3, 2011)

The armor penetration figures given are for tungsten cored shot. Using normal AP shot penetration falls to 32mm or under. Germans had a shortage of tungsten and while they did use in the aircraft guns for tank busting (because using the normal shot would have been near useless) equipping hundreds of tanks with guns that are going to out of ammo in short while doesn't make a lot of sense.


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## davebender (Oct 3, 2011)

Why? 

- The Panzer II ausf C and Pz-38(t) are both 10 ton tanks. 
- Both have rough riding leaf spring suspension. 
- 25mm frontal armor on Pz-38(t) ausf A through F is inferior to 30mm frontal armor on 1940 later Panzer II.
- Early model Pz-38(t) use inferior riveted construction rather then welding.
- I haven't seen a production cost for the Pz-38(t). But I doubt it costs less then the dirt cheap Panzer II.

Don't get me wrong, I think the Pz-38(t) was ok for such a small tank. But IMO the similiar size Panzer II would be as good or better if it had a more powerful main gun.


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## Shortround6 (Oct 3, 2011)

Actual armor penetration figures for the MK 101 were 25mm/300m/90^ for the 500gram APHE. This was improved to 32mm/300m/90^ with the later higher velocity 455gram projectile. Both penetration ratings fell of with both angle of impact and range. The Tungsten cored stuff (355 grams) could do 75mm/300m/90 degrees (or better depending on armor)but it's performance fell of worse with both range and angle of impact. Impacting at 60^ caused it's penetration to fall to between 42-52mm. 

As an example of the fall off in performance of the tungsten cored rounds in these small sizes the German and Czech 37mm guns had better performance with standard ammo at ranges over 500yds than they did with the Tungsten cored rounds.

The Pz-38(t) had a least a two man turret and the Germans may have crammed in a third man (loader). in combat this beats the heck out of the one man band act going on in the MK II turret. If you want the MK II to be an effective combat tank it needs to be all new from the top of the tracks up. Not only a new turret but a new upper hull to hold the new turret. 

Dirt cheap is not always an advantage. The Czech tank was noted for it's reliability and cross country performance.


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## davebender (Oct 3, 2011)

I doubt any tank with leaf spring suspension had good cross country performance as the ride would be rough. 

Germany developed torsion bar suspension for the Panzer II during 1941 but that's too late to matter for such a small tank. Under different production circumstances it might have made a good full track APC chassis.


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## Shortround6 (Oct 3, 2011)

The engine in the 38(t) was about 25% bigger in displacement which means more torque. Nobody was doing more than 8-12mph cross country no matter what suspension without throwing the crews around. Many tanks only had shock absorbers on first and last road wheels if they had them at all. Cross country ability is also hill climbing, ground loading, and a bunch of subtle things not usually found on quick fact sheets. British Churchills could climb hills better than Shermans despite much lower top speed and the later Centurian was also better in very rough terrain than the M-46-48 series. They may have moved at a walking pace but that is better than not moving at all. 

A several variants on the 38(t) chassis went to 15-16 tons. The MK II didn't go beyond 11.5 tons without a suspension change. Granted they might have put heavier springs in the heavy 38(t)s but they didn't add road wheels or change the entire suspension.


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## parsifal (Oct 3, 2011)

Germans used their light tanks, principally the PzII and Pz 38 as Assault guns later in the war. Basically rip out the turret and replace with a gun 75mm or 76.2mm. SPGs with this armament was a better re-use of a scarce tank chassis that refitting or redesigning it with an already inadequate gun. 

Pz IIs were only ever intended as stopgaps. Sounds to me this upgrading scheme would be a major investment in redesign for not much return. Germans were pinning their hopes on the Pz III/IV combination, with the PzIII equipped with a 37mm gun when designed.

Re-equipping the PzII with a redesigned experimental gun in a redesigned turret in a redesigned turret ring takses the PzII from nbeing dirt cheap, into the realm of the problematic.....


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## davebender (Oct 3, 2011)

IMO a 50% weight increase is not a variant. It's an entirely new armored vehicle chassis even if it's derived from an older vehicle. Anyway this isn't meant to be about armored vehicles per se. 

Getting back to the main topic...
Early model Marder IFVs weighed 28.5 tons. By 1989 the upgraded Marder A3 weighed 35 metric tons. Similiar in size to a T-34 or Sherman tank. So why is it still armed with a 20mm cannon? The Heer could have chosen something larger such as the M242 chain gun (i.e. Bradly IFV) or 30mm Rarden cannon (i.e. Warrior IFV) and still had room for an infantry fire team.


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## Shortround6 (Oct 3, 2011)

what is the point? None of those guns will take out a tank except from the rear. APC were/are turning into light medium tanks with an infantry component. Bigger guns mean less ammo. If you want to blow up enemy armored vehicles just put a missile or two on the vehicle. At the cost of a modern IFV the cost a missile is a cheap kill and you still have the 20mm for soft vehicles and general support. Maybe the Germans like the idea of just enough gun to do the job without giving the Marder crews delusions of grandeur about tank hunting.


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## parsifal (Oct 3, 2011)

You would have to say, however that Marders along with the US Bradleys are an over-investment for limited protection. Maybe thats what Dave is on about, though I doubt that upgrading to a 30mm cannon will make any difference to the survivability of the type.

Israeli doctrine does not support frontline use of APCs as MICVs. They have found that in their normal operating environments, such vehicles are far too vulnerable for any such role. I have my doubts about the whole MICV concept.....riding into battle in a AT rich environment in inadequately armed and protected vehicle is a sure way to get a whole bunch of Infantryman killed IMO. The Marder /Bradley options add to the conundrum by making such vehicles expensive additions to the inventory....reduces the number that can be deployed because such vehicles are too expensive.

There were problems in the Iraq deplyment of the bradleys, though I forget what those issues actually were


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## kettbo (Oct 4, 2011)

Having served some 8-9 years on Bradleys in every crew and platoon position during my 20 years of service as a Cavalry Scout, I can share some insights.
20mm (German) and 25mm (Bradley) do terrible things to light armored vehicles, soft targets, troop type targets
Yes, the Bradley is complex, costly, but it is capable, very capable. Great mobility and a healthy cruising range. The best defense is a good offense!!! Pretty tough cookie though not a tank by any means. Great sensors, great fire control (the last 12 years or there about with the Laser Range Finder), outstanding weapons. 

NEVER EVER consider a single piece of equipment on a modern battlefield as stand-alone.
You'll not find too many people these days blindly charging into a stiff defense. In a suspected AT-intense envoronment, before the attack, Air Scouts, UAVs, Multi-Sensor assets, or 19D Cav Scouts infiltrating prior to or ahead of the attack locate said AT weapons and cause their destruction via TacAir, Gunships, or indirect fires. Or simply avoid the area of heaviest defense. There are too many good weapons available to make the enemy 'good enemy.' If you have 120mm mortar fire "Immediate Suppression" or "Final Protective Fire" you would be amazed at the destructive fire by this BN asset., "No waiting" so to speak compared to 155mm fires from supporting artillery. We would often team 3 M-3 CFV with two tanks, hunter-killer. I'm sure you can find a Combined Arms Live Fire Exercise video on YouTube, lots of destruction in a very short period. 
Here is one such vid

_View: https://www.youtube.com/watch?v=2cRp-fJNl-4_
something for everybody here. the vid does a good job of showing all the pieces, the last bit shows everything going on at once when all the cards are played.

Sure, from time to time something gets missed and there will be AT vs BFV action. The platoon vehicles are scanning through thermals or optical sights, covering one another. Suspected areas are neutralized with Smoke/WP or HE, or direct fire from the BFVs 70/230 25mm rounds in the ready boxes. The M-2 Infantry fighting vehicle carried less ammo and missiles due to carrying the Infantry squad. The M-3 CFVs had considerable space and stowed a considerable arsenal. The 25mm ammo boxes had switches for the rounds in each to adjust the reticle reference. Often the CFV would be AP-heavy with Sabot in the 230 box and 70 HE in the small box. This in order to defeat enemy recon vehicles, PCs, etc.

vs Tank, really not where you want to be, especially in the offense. Operating as sections with Bounding Overwatch, one section covers the other as they move. Covering section has the TOW launchers up, scanning, preferably from some sort of protective terrain or hull down. On the defense, certainly under cover with only the thermal sights exposed... Leave enemy tanks for your tanks or the gunships.


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## parsifal (Oct 4, 2011)

Hi kettbo

I know that the bradleys are an exceptionally capable piece of kit, as are the marder2s. however, i guess I am looking at the issue from the quatermasters POV, and comparing that to some of the "cheaper" options kicking around at the moment. 

Bradleys cost something in the order of $7m (Au), per copy. A Marder2 if it were being produced today would cost about $9-11m (AU). If you compare that to say our ASLAV-25, which is similar to your LAV-25, but with enhanced fording and amphib capability, the cost is about $2.5m per copy. ASLAV/LAV -25s carry the same armament....dont know the sensors, but I expect are similar, are AWD rather than tracked, and only very lighly armoured (designed to withstand small arms). Obviously they are a more limited vehicle than the bradleys, but for every one Bradley you can have nearly three ASLAVs. But its worse than that. If your Bradleys are even remotely similar to the old M-113s (shows my age, but thats equipment I am a little more familiar with), the tracked APCs wont have near the longevity between refits. M-113s needed a complete replacement of tracks every 5000 kms or so. ive heard Bradleys suffered similar serviceability issues in Iraq. LAVs I am told just kept going and going.

So, taking into account the servicieability issues, which is the better deal...having one Bradley, or 4 or 5 LAVs. 
Australian Army in Afghanistan and iraq, have gone even lower in the firepower stakes, so as to enhance reliability, and lower cost. our bushmaster vehicles are armed with nothing bigger than a 50 cal, and are only 4wd as opposed to 8WD in the LAVs. They are armoured, but even less so than the LAV. Yet they cost only a fraction, at $0.5m per copy, and with very high rates of serviceability. We have found these typeds of vehicles in places like Afghanistan a far better option than even the ASLAV. 

Unless the army has unlimited resources, it makes sense to opt for reliability at the expense of hi tech sophistication. Tracked APCs, tend to be just that, and APCs with high levels of firepower tend to be a waste. I happen to think the best compromise is the LAV option, but perhaps I am wrong....


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## davebender (Oct 4, 2011)

Nor do they need to as we are now discussing an IFV. Primary purpose of the main gun should be to provide infantry with effective fire support. That eliminates the WWII requirement for specialized infantry support vehicles such as the StuGIII, Su-76, Sherman 105 and various British infantry tanks. Perhaps the German Rh202 20mm cannon works well for that purpose. But to me it seems a bit small for defeating dug in infantry. On the flip side, Rh202 cannon rate of fire is outstanding compared to larger IFV weapons. It must be murderous against soft skinned vehicles and infantry caught in the open.

*Flugabwehrkanone 20 mm Zwilling*
Rheinmetall 20 mm Twin Anti-Aircraft Cannon - Wikipedia, the free encyclopedia





If mated with an effective fire control system a pair of Rh202 cannon ought to turn any aircraft into Swiss cheese. Lightweight and compact too. Looks like a worthy sccessor to the WWII era flakvierling. But it has a short effective range just as the WWII era weapon did. Perhaps that's not an issue as long range flak is now accomplished using surface to air missiles.


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## kettbo (Oct 4, 2011)

Just a word on AAA
If the flyboys see tracers zipping past, concentration on the flying, bombing, switchology tends to suffer.
Nobody wants to get hit by a Golden BB so until neutralized, AA fire will be avoided.



The threat of a major war in Western Europe (la raison d'être for the Bradley and Marder) diminishing, only low intensity conflict on the horizon, the US Army switched to Stryker production. The Stryker allows more units to be built, easier deployability, less maintainence heavy for sure, and less fuel used.
The trade off is less protection and less firepower per vehicle. Many versions of the Stryker; one for recon, Infantry, AT Missile, tank-like AGS
I have no personal experience with Strykers in deep mud such as we encountered regularly at Grafenwohr or Hohenfels or a Korean winter. Fair or mild weather, roads, advantage to the wheeled vehicles. Cross country, mud, bad weather, tracked is where it is at.

5000 km is a very long time for a tracked vehicle if you think about it. I have seen quite a few tires flattened/shreaded and wheels blown off by stuff that whould not phase a Bradley or Marder. Lots of hi-tech stuff out there allows more to be done with less boots on the ground.

25mm DU rounds have been known to penetrate older WP tanks
10-15 rounds into the side/rear of a T-72, could get interesting. Not a good way to make a living however, too risky. But tanks have optics and other vulnerable things that can be damaged if you cannot get killing hits.

.50 cal has impressive penetration. In a power mount with optics, quite lethal on point targets at usable distances. But I must return to what I said earlier about multi systems. Pin the enemy to fix his position, then call in 120mm mortar, artillery, or air to eliminate him. With 20mm, you get longer range and some explosive in the projectile, better penetration. 25mm, more of the same. 

Which system works better? For Iraq and Afghanistan, the lighter vehicles do well. A major confrontation in Europe over real estate could have those with lighter vehicles at a major disadvantage. Regrets, "Joe" does not get to choose where he goes to war or what he is equipped with.


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## davebender (Oct 4, 2011)

Marder and Bradley IFVs have been deployed to these conflicts. Which main gun has proven better in modern combat?

25mm M242 chain gun (i.e. Bradley IFV). 200 rounds per minute.
20mm Rh202 cannon (i.e. Marder IFV). 1,000 rounds per minute.

I suspect the larger 25mm rounds would be superior for fighting enemy BMPs. But what works best vs enemy infantry? That Rh202 cannon can put an impressive quantity of 20mm mine shells on target.


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## kettbo (Oct 5, 2011)

Neither system is healthy for enemy infantry!
Bradley gunners are trained one sensing round, correct and fire a 3 round burst, then final adjustment and a 4 round burst. Assume the sensing round is a complete miss, then you still have 7 glowing baseballs intering the proximity of the enemy troops, and they blow up like grenades at impact.
Not really sure about the Marders, figure two bursts of around 8-10 each, 16-20 smaller explosions (just a guess, they gotta keep a eye on ammo use too)

In either model, lots of stuff going whizzz BANG around the bad guys and lots of flying shrapnel and secondary debris looking to pierce flesh from the ground or walls nearby.
Other things to consider are bore life (too many rounds in a short time period gets the barrel too hot, later fluted barrel holds up better), supply situation, number of targets.


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## parsifal (Oct 5, 2011)

Ive seen vision of ASLAV-25 gunners engaging the bad guys....its exactly the same procedure as you describe. targetting information passed by the commander to the gunner, with the gunner also having a night vision or image enhancement aid (not sure what the commander is using, but targetting equipment is pretty sophisticated by the look of it). 

The standard procedure for our Armoured Cav guys is to fire a three round burst and observe. Either the gunner or the commander can use follow up burst if there is any residual movement of the target.

The vision Ive seen is using the image enhancer, and engaging three or four targets simualtaneoulsy at night. The targets are dispersed at the beginning of the sequence, and are seen scurrying for a while, but these guns appear deadly, and deadly accurate. i would not like to be on the receiving end of these boys. The 25mm has no difficulty in achieving 1st burst kills for multiple targets. I dont know the engagement range, but it looks like it was at least 800m. 

ASLAVs in the Australian Army are not generally used in the APC role though they can. They do however undertake recon and fire support for the grunts on the ground. The army is very pleased with their performance. Our principal APC remains the locally produced Bushmaster (not the gun, the vehicle), but our infantry does not use these vehicles as battlefield transport. They disembark outside the combat zone if possible, though there have been incidents in Afghanistan and iraq where they have been in the middle of a battle. They are better than a humvee, being resistant to IEDs and small arms, but an RPG will tear a hole in them.


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## davebender (Oct 5, 2011)

How much HE filler in a modern 25mm shell vs how much HE filler in a modern Rh202 20mm shell? The 20mm shell HE content gets multiplied by 5 (i.e. 5 x ROF) giving us a rough idea how much HE each cannon can place on infantry or other soft targets.


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## davebender (Oct 5, 2011)

M242 25mm Automatic Gun
32 grams of an HEI mix

Answered half my question..


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## Shortround6 (Oct 5, 2011)

trouble is they don't carry five times as much 20mm ammo in the vehicle.


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## psteel (Oct 6, 2011)

20mm gun was very reliable and had long barrel life > 20,000 rounds....The best competitors got 8-10,000 rounds.
German doctrine was to run armored infantry independant of panzer units and the vast majority of the targets on the modern battlefield were troop soft targets or light armoured.

Re Pz 38t when the Pz II was upgraded to 30mm frontal armor the Pz 38t went up to 50mm. Their are instances where the Pz 38t took on KV tanks and beat them. Don't recall any such incident with Pz-II.

Personnally if I was running German rearmament in the 1930s I would have licence produced Pz-35t and then 38t instead of the Pz I II III IV. Meanwhile I would redesign the the Pz-III IV into a single model [with optional armament [infantry gun or PAK] for mass production to begine when war began.

Once Pz IV3 production begins the Pz 35t would be delegated to recon role and mass conversion to a SP gun [75mm IG in open mounts] for the Motorized infantry Divisions, while Pz units would be mix of Pz-38t with growing number of PzIV3. After a year or two the entire Pz 35/38 inventory could be converted en mass to mount French 75mm guns /later the Pak40 or captured Russian 76mm guns [AkA Marder] to suppliment Motorized infantry divisions and fill out PzJagger battalions. Later this same light tank industry could be utilized to build Marders or Grille SiG 15cm guns and ultimatly the Hetzer assault gun and follow on Waffentragger role, which would be taken over by the Zg tractor production [~ 17,000 per year].


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## tomo pauk (Oct 6, 2011)

The best role for the MK-101/103 would've been as the main armament of some kind of SP AAA vehicle, IMO. So let's redesign the Pz-II in order to have the 3cm Flak on-board - a half scale Moebelwagen?


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## davebender (Oct 6, 2011)

> best role for the MK-101/103 would've been as the main armament of some kind of SP AAA vehicle


That's what they did during 1945. The Heer designed a new 3cm twin flak turret which could be mounted on a wide variety of vehicle chassis.
Achtung Panzer! - Prototypes !






The German Navy designed a streamlined twin flak turret for the Type XXI submarine. Each boat had two such flak turrets. Early production boats had 2cm weapons in the turrets but they were designed for a variant of the 3cm cannon.

On the same subject.
The late war 3.7cm Flak43 was essentially a larger version of the 3cm Mk103 cannon. It may have been the best medium flak weapon produced by anyone during the WWII. I've never read of it being employed in the AT role. However with APCR rounds it probably had some potential vs armored targets.

*3cm Mk103 Cannon.*
420 rpm.
.330kg Projectile weight.
960 mps AP projectile velocity.

*3.7cm Flak 43.*
250 rpm
.685kg AP projectile weight.
790 mps AP projectile velocity.
.....Velocity is lower but projectile weighs twice as much. Not sure how that works out in terms of energy.


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## psteel (Oct 6, 2011)

That would not work on a Pz II chassie. Too big Flak gun. Best I saw was a single flak on a Marder chassie. Besides there were more important roles to fill than SP flak . The Sdkfz SPW-251 could be adapted to fill such a role. Pz-38t was however very valuable as a "Grille" for the 150mm Infantry gun.


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## davebender (Oct 6, 2011)

By 1945 it was a moot point as the 10 ton Pz II chassis was out of production. For that matter so was the 10 ton Pz38(t) chassis. However I think they were planning to mount a twin 3cm turret on the new 15 ton Hetzer chassis.

The 8 ton Spw-251 half track was probably too small for a twin 3cm turret. However they made a variant with a triple MG151 mount. Not a long range weapon but the sdkfz251/21 could certainly put out a lot of rounds. The gun crew looks well protected too compared to many early war flak mounts.


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## Shortround6 (Oct 7, 2011)

davebender said:


> *3cm Mk103 Cannon.*
> 420 rpm.
> .330kg Projectile weight.
> 960 mps AP projectile velocity.
> ...



Do try comparing like to like. 

The standard AP rounds for the MK 101/103 had weights of 550 and 455 grams with velocities of 690mps and 760 mps. MK 103 may be down slightly. the 335 gram AP projectile was the tungsten cored one. 
The tungsten cored shot for the 3.7cm Flak 43 weighed 405 grams and had a MV of 1040mps. This projectile did not have the streamline shape of the 30mm round and would have lost velocity much quicker however.


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## tomo pauk (Oct 7, 2011)

davebender said:


> That's what they did during 1945. The Heer designed a new 3cm twin flak turret which could be mounted on a wide variety of vehicle chassis.



Hold your horses  
I've never said: "let's make a two-gun turret and mount it to a 20-ton chassis", but: "let's mount the gun on the 10 ton chassis, akin to Moebelwagen". So, a single cannon, mounted on Pz-II. Very much feasible in 1942.


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## davebender (Oct 7, 2011)

Heer light flak spent more time firing at ground targets then at aircraft. A flakviering or triple MG151 mount was more useful then a single 30mm cannon for chewing up enemy infantry while still providing decent AA protection. 

WWII Germany was out muscled in GDP compared to the Allies so it was important to get the most bang for the buck. That's why so many weapons such as the Me-109 fighter and MG-42 machinegun were less expensive then Allied counterparts. The Panzer II was cheap but a Spw-251 was even cheaper and the half track could adequately perform the moble light flak mission.


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## tomo pauk (Oct 7, 2011)

A Flakvierling requires more crew (eight men for towed variety) to operate, than a belt-fed 3cm weapon, while it provides just half of the useful range vs. aerial targets. 3cm has useful range as good as 3,7cm (circa 3km). The 20-round boxes (for 20mm) cut practical rate down at 40% of the cyclic - not issue for belt fed weapon. Flakvierling required 20 ton chassis, out of question for dirt cheap  Pz-II. Of course, why not mount the 3cm at SdKfz-251?
Forgot to say, with 3cm you have some chance to pierce some armor, compared with what 2cm was able.


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## davebender (Oct 7, 2011)

The flakvierling weapons system weighed only 1.5 tons. Consequently it could be mounted on trucks and half tracks without difficulty. The Sd.kfz7/1 is one of the more common installations. However over the course of the war it was mounted on practically everything including captured British made Bren carriers.

2cm Flakvierling 38 auf Selbstfahrlafette Sd.Kfz.7/1


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## davebender (Oct 7, 2011)

20x139 shells for the HS-820 (Oerlikon KAD) Rh-202 gun - wk2ammo
Penetration: 35mm armour steel plate at 1000 mtrs. @45 degrees

Incredible for a 20mm cartridge. I'm starting to understand why the Rh202 20mm cannon is so popular.


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## psteel (Oct 7, 2011)

davebender said:


> By 1945 it was a moot point as the 10 ton Pz II chassis was out of production. For that matter so was the 10 ton Pz38(t) chassis. However I think they were planning to mount a twin 3cm turret on the new 15 ton Hetzer chassis.
> 
> The 8 ton Spw-251 half track was probably too small for a twin 3cm turret. However they made a variant with a triple MG151 mount. Not a long range weapon but the sdkfz251/21 could certainly put out a lot of rounds. The gun crew looks well protected too compared to many early war flak mounts.
> View attachment 180048



Yes thats what I'm talking about. By 1945 all light chassie production had been switched over to the Hetzer chassie and the Waffentragger.SP flak would be low on the list of priorities for the Heer. As it was about 1500 Zg 3/4 track were utilized to mount flak guns up to 37mm flak.


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## davebender (Oct 7, 2011)

During 1942 RLM issued an advanced specification for a 20mm cannon. 1,000 rpm and 1,000 m/s projectile velocity. The MG213 revolver cannon won the competition and was almost production ready when WWII ended.

However it wasn't the only weapon in the competition. There was a conventional gas operated autocannon designated "MG301". Does anyone have additional information on this weapon?


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## vanir (Oct 19, 2011)

There's a cultural perspective being missed here. Germans don't consider the 20mm a cannon calibre. Anything under 30mm is a machine gun calibre to them. So it's the largest machine gun calibre with the best all round performance compromise between smaller/larger calibres in many specified roles. Just like the .50 cal is for the Americans.

The 2cm machinengewehr round is to the germans exactly what the .50 cal machinegun round was to Americans and the .303 to the British. Reliable, quantifiable performance.

That said 3cm or larger was preferred for FlaK, the Mk101 you're talking about, similar but slightly higher charge weight and muzzle velocity, more recoil, comes in both percussion and electrical ammo (percussion ones were used in Romania).
Thing was Luftwaffe security forces formed the centralised FlaK formations in Germany and at forward airfields so got preference, they got all the 3.7cm SPG/AAA whilst Army got all the 2cm.

It was just the way it worked out, check out the OOB by unit and you see army with 2cm FlaK and luftwaffe FlaK with 3.7cm, both have 8.8cm. This also suggests that around command posts ground attackers will face 2cm point defence, near airfields it will be 3cm as a general rule, you can find targets by what is shooting at you.

I realise what I said is confusing, Tony Williams iirc told me about Mk101 based FlaK used around Romania, and LW got the lions share of 3.7cm.


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## parsifal (Oct 19, 2011)

Hi Vanir

havent seen you aropund that much, but perhaps youve just been lucky we havent crossed paths lately..... good to hear from you anyway.


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## johnbr (Oct 21, 2011)

Here some info on the Mg 301 MV-1000m/s(3281 ft/sec),cyclic rate of fire 1000 rds/min,weight 55kg(121.3lbs)muzzle energy 5.2 mt(37612 ft lbs),gas operated with horizontal wedge lock and shortened bolt travel belt one side only,electric primer.MG 213a 20mm Further development of MG301 employing Krieghoff's system.By Mauser at direction of Air Force High Command Characteristics same as MG 301 Modification of MG301 for Functional and manufacturing reasons.Belt feed right or left Several Experimental Specimens produced.This from the Book German Aircraft guns ww1-ww2.


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## vanir (Oct 22, 2011)

parsifal said:


> Hi Vanir
> 
> havent seen you aropund that much, but perhaps youve just been lucky we havent crossed paths lately..... good to hear from you anyway.



Oh mate I'm a boring fight. Even if you think you win, I just leave. I don't want to play king of the castle with you, but I'll tell you I'm as often wrong as the next person but I always know what I'm talking about. If I've had problems with you in the past, it is wholly because you took exception to that piece of democratic freedom.


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## davebender (Oct 23, 2011)

Looks like the missing link between the 2cm Flak38 and the 1960s Rh202 cannon. I'm surprised the Heer didn't adopt it towards the end of WWII. A twin Mg301 would have a greater rate of fire then the widely used flakvierling and you'd probably need only half as many crew members.


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## parsifal (Oct 24, 2011)

vanir said:


> Oh mate I'm a boring fight. Even if you think you win, I just leave. I don't want to play king of the castle with you, but I'll tell you I'm as often wrong as the next person but I always know what I'm talking about. If I've had problems with you in the past, it is wholly because you took exception to that piece of democratic freedom.



I dont think we had any problems, just saying hi having not seen you in a while


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## davebender (Oct 25, 2011)

Source. Zaloga and Ness. Red Army Handbook 1939 - 1945.
20mm. 4.7%
37mm. 10%
50mm short. 7.5%
50mm long. 54.3%
75mm. .1%
88mm. 3.4%
105mm. 2.9%

It's readily apparent the German 5cm/60 cannon was a serious tank killer. However I find it interesting that almost 5% of Soviet tank losses were caused by 20mm fire.


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## Denniss (Oct 25, 2011)

davebender said:


> It's readily apparent the German 5cm/60 cannon was a serious tank killer. However I find it interesting that almost 5% of Soviet tank losses were caused by 20mm fire.


Lots of old/light tanks still in service ? T-26 or BT series should be vulnerable to 2cm guns if coming too close.


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## vanir (Oct 25, 2011)

2cm PzPatr standard AP can manage up to 24mm penetration on case hardened steel at 90-degress, 12mm at 60-degrees (a good hit angle in combat). Only the thinnest, lightest tank armour is going to get reliably penetrated and things like netting and external gear will really soak them up and double protection.

You want Mk101 style 3cm minimum against case hardened tank armour, but you'd go at SPG with 2cm batteries.

Oh hey, but one of the good things about older tanks from an enemy's point of view is spalling. Expecially things like T-26 with rivets.


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## davebender (Oct 25, 2011)

Sure if you have a choice. But sometimes you don't get a choice. 

I had an Air Force guy tell me the A-10 30mm cannon chews through modern tank armor by landing multiple hits in close proximity. Perhaps the WWII era flakvierling works the same way vs 45mm thick T-34 armor.


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## parsifal (Oct 26, 2011)

Just remember that airborne AT is more an implied threat than a real threat. The most effective airborne tank killers at Kursk were HS129, equipped with a high powered 20mm cannon. There is no doubt this weapon could in theory penetrate the deck armour of a T-34. However claims of the LW AT aircraft are grossly overblown, as are those made by the VVS against the Heer. Instead of the 500+ tanks destroyed by the LW, as claimed, it appears maybe 150-200 were actually destroyed. For the Soviets, instead of the 400+ tanks that they claimed were destroyed by sturmoviks....maybe 90 at most.

In 1944, Allied claims of destroying over 100 tanks attached to the Lehr Division are grossly overblown. instead, prior to Falaise, maybe 2 or 3 tanks were destroyed by direct air attack. What did suffer were the soft skinned vehicles and light AFVs, like Halftracks and the like.


Its not that airborne AT threats in WWII were not crucial, they were, but they just were not that effective against fully armoured targets. What they did do was to interdict, and restrict flexibility for a ground force threatened by such attack. The tanks represent just a small fraction of the force structure.....if the force canot move by day because of the threat of air attack its mobility options are severely restricted. This is basically what happened to the germans at Normandy


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## davebender (Oct 26, 2011)

That's not surprising since the LW had so few dedicated AT aircraft.

The Me-110 could carry a 3cm Mk101 cannon but I doubt more then a couple dozen were employed in the AT role. Cannon armed Ju-87Gs probably amounted to less then 300 total aircraft. Perhaps 800 cannon armed Hs-129B2 and Hs-129B3 aircraft saw combat. 1,100 cannon armed AT aircraft would be a considerable number if available for a single battle but it doesn't amount to much when spread all over Europe, Russia and North Africa over a 3 year period.

Not that this has anything to do with Heer use of high velocity 20mm cannon against ground targets.


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## davebender (Oct 26, 2011)

http://mildepot.files.wordpress.com/2010/10/historyguns.pdf
I thought this was a myth but apparently it's true. Issued on the Eastern Front during June 1944. 100mm armor penetration @ any striking angle. And that's using only a 30mm cannon.

It's a good thing for us that 1944 Germany had a limited supply of Uranium.


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## vanir (Oct 26, 2011)

The Mk101 was adapted to a couple of Me-110E of ZG26 with Luftflotte 2 (kommando tunisia/fliegerfürer afrika presumably) but was being produced for the Hs129B. Later they got the Mk103 and FlaK based Bk3.7 option on both the Henschel B-2 and 110G-2 as standard kits. They're both real good against light tanks but would have serious troubles with something like a T-34/85.

There was no special high velocity 2cm I can think of on the Hs129 at Kursk. These should've had Bk3.7 and Mk101/103, standard armament is 2MG151/2MG17.
The Soviets were trying out their new Nudelmans on sturmoviks and even put a few in escorting Yaks. Surplus LaGG were fitted with upgraded 23mm nose guns about that time period and reportedly also used as sturmovik escorts, as were La5 strapped with bombs.
German reports of these sturmovik formations battle effectiveness against tanks is noteworthy, I've read field diaries describing the Il2 circling tank lines and making repeated passes at the rear/upper armour until their ammo ran out or all the tanks were destroyed, despite being continually pounced on by German fighters. They attacked without regard for Luftwaffe local air superiority and were very effective at disrupting formations for infantry assaults, these were the kind of comments I read. What I read for equipment used in the field is that attacks by sturmoviks on tank formations uses big Nudelmans, and AP/shaped charge rocket volleys, and canister munitions, and bombs, and repeated strafing in concert with rocket attacks.

As for a rocket attack, say for a Typhoon volley I've read such colourful terms as "equivalent to a battleship broadside" in general publication. When a vet Sherman commander from D-day was being interviewed he talked about three Tigers up on a hill that held them up from breaking out a whole afternoon. He said the next day Typhoons destroyed them in a rocket attack. He didn't make it sound like they drove away.
And finally there are photos roaming around with tanks missing turrets and the caption claims it was an Allied aircraft rocket attack that did it.

I agree that a lot of aerial tank kill claims appear to be grossly overstated, however some of these weapons used are quite capable of reliably destroying tanks...conditionally speaking.


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## kettbo (Oct 27, 2011)

Rear of tank not heavily armored nor is the back deck nor turret roof. 20mm adequate, multiple 20mm more than adequate until later vehicles were armored better. Then 30mm a more realistic weapon.
Some vehicles blow up after catching fire due to engine area hits. Fuel then was usually gas except some Shermans used by the UK (and USMC in the Pacific) and the T-34 and later Soviet tanks. Maybe the lighter tanks taking direct hits turret roof could blow due to ammo hits. Even the Tigers and Panthers were vulnerable to rear deck engine grate hits. You can see mods of plates fitted above the grates to reduce this, late 44.
Open hatches are not proof against anything
Rockets are pretty nasty things though not particularly accurate. 

For ground mount weapons, the lower hull side is generally very vulnerable if you can get shots in there. Everything cannot be well armored if mobility is a concern.


Most of the blown up/missing turret vehicles were crew-destroyed to prevent Allied use.....clue would be no corpses or body part in the pictures. If you see body parts, then the vehicle is no doubt a combat casualty of some kind.

Air attack forces the tanks to button up which greatly reduces crew effectiveness.


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## Denniss (Oct 27, 2011)

The first reported usage of the MK 101 on the Bf 110 was with the experimental Zerstörer C-6 (12 built). Intended for Anti-shipping strikes it did not really prove to be successful. I don't know what happene to these 12 aircraft - I assume rebuilt as standard fighter-bomber.


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## parsifal (Oct 27, 2011)

This is a direct quote I have taken from another website (The Dupuy Institute) authored by Chris Mitchell , a moderator of that site, and author and associate of Zetterling. It highlights some of the problems and information issues that need to be considered with any reports about tank Busting aircraft......

"I have been asked over the year(s) by Niklas Zetterling, Jeff Duquette and others about the particular stories about the effectiveness of the Hs-129 B-2s and Ju-87 G-1s in tank busting, particularly on July 8. Nearing completion of this section in my book, I am now prepared to discuss it.
There are two seperate stories of German tank busting that circulate about Kursk. First is the Rudel story that on or about 7 July he personally killed 12 tanks with the new experimental Ju-87 G-1 (the Stuka with the 37mm cannons) and this lead to the formation and use of the tank busting stuka squadrons.
The second story is the Maj. Bruno Meyer story about seeing a Soviet tank brigade coming out of the woods at Gostishchevo on July 8 and calling in all five squadrons of the IV/9th Ground Assualt Wing of Hs-129s B-2 (the Hs-129 armed with the 30mm cannon) and halting the attack by destroying 40-50 Soviet tanks in a short time

This story was first published by Hans Seidemann (VIII Air Corps commander at Kursk) in 1947 as part of his write-up he did for the US Army on air operations at Kursk.

It this story, he clearly identifies the time and date (afternoon of July 8), the location ("from the woods east of GOSTCHEVO station"), the unit ("4th Group/9th Antitank Ground Attack Wing"), the German air response ("in a short time, they were on their way to meet the enemy force"), the duration of the battle("after about one hour") and the result ("approximately 40 tanks had been knocked out") and its effect ("the remainder of the enemy force discontinued the attack and turned around"). Furthermore, he identifies elsewhere the strength of the antitank unit as 60 planes. 

This story has the advantage of being specific enough that one can acually compare it to the opposing side's records (unlike most war stories).

There is some other confirming evidence for it in the German records. Primarily there is a claim in the VIII Air Corps records that they destroyed 84 tanks on the 8th, including 11 burned and damaged 21 tanks on July 8 and the comment for that day that the "The initial action by the antitank aircraft squadron was quite effective. Given the number of burning [enemy] tanks reported, it must be assumed that there was an even greater number that were just knocked out (more than 6 hits reported), Especially in the late afternoon attack from the northeast against SS Reich and the evening tank battle, the Russians were stopped and driven back."

The VIII Air Corps also reports the loss of two Hs-129s on this day

Over the years, an expanded version of this story has appeared, I gather first from a German source that I have not identified. It shows up in Robin Cross' "Citadel: The Battle of Kursk" book (pages 198-199) and in a number of web sites about Hs-129s. A German site that has the story is linked below, and it appears to have been drawn from the same source as the Robin Cross version.

The expanded version of the story has Major Bruno Meyer flying reconnaissance in the morning, when "as the morning mist clears" he sees 60 tanks and their supporting infantry emerge from the woods. He calls in all the units of his group with the lead elements arriving from Mikoyanovka airfield within 15 minutes. They are supported by Fw-190s lead by Maj. Alfred Druschel (CO 1st Ground Attack Wing), who bomb the supporting infantry. They usually have the battle resolved in an hour, with Cross' claiming six tanks "within a few minutes" and 50 tanks within an hour. Most accounts claim 40-50 tanks. All the accounts place the attack on the flank of the SS Panzer Corps or the woods near Gostishchevo. The account often provide a detail OB of five squadrons with 16 planes each.

This is clearly the same story, with some detail added.

The German language version of the story is at:
http://www.wehrtechnik.net/wehrtechnik/henschel_129.html

Now, before we take a look at the Soviet data...there are a few problems with the German reports.

First, this attack is noted in the German SS Panzer Corps reports as an attack at 1145 with 20-40 tanks and weak infantry units through the ravine from Visloye and Ternovka to the west agains the defenses at the Belgorod-Kursk highway.

Visloye and Ternovka are both in front of the large woods south of Gostishchevo. This raises questions at to both the time and size of the attack (and therefore casualties).

Next, the sources I have located indicate that the IV/9th SG was created 18 October 1943 and its commander was Bruno Meyer. The III Pz Corps records do make reference to an panzer command as part of the 1st Ground Assualt Wing, but I do not know who commanded it, or what it consisted of. There were two AT squadrons (the 4th and 8th) armed with Hs-129s in the 1st SG. There is clear evidence that the 4.(Pz)/2 SG was also there as was the Pz. Sqdn/51 JG. All four of these squadrons were later used to create the IV/9 SG along with the 8.(Pz)/2 SG. I do not have clear evidence than this last unit was at Kursk, but I assume it was.

A good bio of Bruno Meyer would be of use here.

Third, the base listings I have put these Hs-129 squadrons at Varvanovka, not Mikoyanovka".....(to be continued)


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## parsifal (Oct 27, 2011)

(Continuing on)...."Conveniently enough the Soviet attack is clearly identified in their records and there is only one brigade it could be.

This is the 26th Tank Brigade of the II Guards Tank Corps. It is the only candidate and was reported at attacking from Visloye at 1200 Moscow time (1100 Berlin time). 

There are no other candidates. The division operated with two tank brigades forward and one in the second echolon. The other forward brigade (4th Guards Tank Brigade) was to its right at Nepkhayevo while the other tank brigade remained in the rear. The Corps 47th Heavy Tank Regiment (Churchills) was already 7 - 10 kilometers away in the III Panzer Corps area engaged, and the independent 96th Tank Brigade was moving southeast of Gostishchevo and joined that fight.

Therefore, one is left with the 26th Tank Brigade. It reports that it attacked from Visloye at 1200 (Moscow) time. Visloye is at the northwest tip of the large woods south of Gostishchevo. This attack drove onto height 209.5, two kilometers southwest of Visloye. The brigade then reports being attacked by 40-50 planes during the German counterattack (which occurred at 1210 Berlin time according to German reports). 


The 26th Tank Brigade as of 0700 July 8th has 26 T-34s and 15 T-70s. The attack also included one regiment from the 4th Guards Motorized Brigade, which may have included up to 20 Bren Gun Carriers. It was also supported by infantry from a Rifle Division.

The Corps reported losing 8 T-34s and 3 T-70s for the day, with effectively only two of its brigades engaged. The 26th Tank Brigade at 0700 July 10 reported having 22 T-34s and 12 T-70s. The Corps reports only losing Churchills on the 9th. From 0700 on the 8th to 0700 on the 10th, the 26th Guards Tank Brigade shows a decline in ready-for action tanks of 4 T-34s and 3 T-70s, while the 4th Guards Tank Brigade shows a decline of 2 T-34s and 2 T-70s. The 25th Guards Tank Brigade's strength actually increases during this time. The Corps did have a coprs reserve of 20 T-34s and 10 T-70s located in Bubnovo on the 8th. This unit is no longer mentioned and may have been used on the 10th or 11th. 

As the 4th Guards Tank Brigade clearly took casualties, this all points to the actual losses of the 26th Guards Tank Brigade being around nine tanks. Assuming that some were lost to German armor, antitank guns and infantry (both during the attack and during the German counterattack) then it would appear that the claim by the VIII Air Corps of "more than 6 hits" may in fact be high. The claim of 40 tanks killed appears to be off by an order of magnitude."

Niklas Zetterling in that thread comments on the misinformation put out by Glantz and Carell on this incident. He writes "If I remember correctly, Glantz used this version and refered to Paul Carell".

Lawrence replies"

The actual passage in Glantz states (page 135):


quote:
--------------------------------------------------------------------------------
Burdeiny's 2nd Guards Tank Corps fared little better. It jumped off at 1200 hours, and after limited progress suffered an unmerciful beating from German aircraft and Totenkopf's panzer regiment, losing 50 tanks in the process. German aerial reconnaissance had detected Burdeiny's concentration of armor, and four squadrons of Henschel HS-109 aircraft, specially equipped with 30mm automatic cannon for antitank missions, broke up the Soviet attack, perforating the thin overhead armor of the tanks and leaving a hideous, burning wasteland. This unprecedented action, in which a tank attack was halted by air power alone, set a dangerous precedent. Indeed, throughout the battle, Soviet troop movements had to be conducted at night to minimize such lossees. This in turn delayed the arrival of reserves to block the German penetration.
--------------------------------------------------------------------------------

Now, I have a number of problems with this passage....

1. They did not loose 50 tanks. The Corps probably lost as reported 11 tanks on this day.

2. I do not have confirmation as to whether the AT Air Group had 4 or 5 squadrons.

3. The planes were Hs-129s, vice HS-109s.

4. Not sure of the details about "perforating the thin overhead armor of the tanks and leaving a hideous, burning wasteland."

5. The actual description of the operations from the 2nd Gds Tank Corps operational report 182, 0700 July 9, 1943 (page Fond: 2nd Guards Tank Corps, Opis: 1, Delo: 32, Page: 187):

"26th Guards Tank Brigade cross the Lipovyi Donets at 1200 in the area of Visloye, along with 1 regiment/4th Gds Motorized Brigade and 89th Gds Rifle Division, attacked height 209.5. The brigade, despite heavy enemy fire, together with 89th Gds Rifle Division, took height 209.5, after which the enemy launched armored counterattacks, supported by aircraft in groups of 40-50 planes. 89th Gds Rifle Division fell back on Visloye and after an hour 26th Gds Tank Brigade's tanks, having taken losses, fell back on the eastern slopes of height 209.5, where they consolidated and continued to fight the enemy.
At 1800 on July 8 26th Gds Tank Brigade attacked height 209.5 for the second time, but was unsuccesful."

The SS records support this account. Therefore, I must take exception with the conclusion that "a tank attack was halted by air power alone".

Furthermore, this statement about halting a tank attack with air power alone is contradicted by Glantz in his second sentence where he states "suffered an unmerciful beating from German aircraft and Totenkopf's panzer regiment"

6. For number of reasons, I disagree with the conclusion that this "set a dangerous precedent." and that "Soviet troop movements had to be conducted at night to minimize such losses. This in turn delayed the arrival of reserves to block the German penetration."

While the Soviet reserves regularly did travel at night...they also moved surprisingly fast. Any delays in the arrival of the 5th Guards Tank Army and the 5th Guards Army could be better explained by the date they were ordered to depart and the fact that they sent the 5th Guards Tank Army off to Oboyan first before they turned it around and sent it to Prokhorovka. As it was, it appears that the Soviet units had a tendancy to go into battle too quickly from the march and may have done better if they rested and prepared. I do not think that the Hs-129 attack on the 8th of July was a major factor in causing the Soviet Army to conduct night marches, as they had been doing this for a while as a matter of course".


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## vanir (Oct 27, 2011)

General von Mellenthin of XLVIII Panzerkorps wrote of the second day of fighting near Kursk, "...a large number of (Grossdeutscheland's) panzers were blown up by mines or destroyed by (enemy) aerial attacks."

This is a pretty damning description by a chief of staff in the field, I read the distinct inferrance routine aerial attacks at this time were highly dangerous to tanks.



You know what though, this gives me an idea of how the respective men in the field are drawing their own descriptions. You see the Germans are probably describing their experience of soviet tank busting in front of their eyes, those Nudelmans really mess up a PzIV if you hit it anywhere but the front, a PzIII stands up better to the back/sides, so the Germans probably use their experience to describe their own presumed Soviet experience of their own tank busting efforts

but on average, the Mk101 is probably doing more temporary disabling than serious damage compared to 37mm Nudelmans, and a T-34 stands up way better than a PzIV to aerial attack. The whole thing about the PzIV is being lightened on the sides and back so the front could be an assault facing, it was never an MBT.


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## kettbo (Oct 27, 2011)

yup, other than the front hull, the PzKw IV was not well-armored.


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## davebender (Oct 27, 2011)

The Me-110 was designed for optional use of the high velocity 3cm Mk101 cannon right from the beginning. Here is a picture of a Me-110B with Mk101 cannon installation. I assume the Mk101 cannon installation was accomplished with a field kit.
Messerschmitt Me 110dj_f4.htm





Not that the Me-110 has anything to do with use of auto cannons by the Heer.



Bronco Models CB-35057 German 2cm Flakvierling 38 w/Sd.Ah.52 Carriage Trailer




The flakvierling was small enough that it could be easily dug into a defensive position. Heer doctrine called for them to be placed on the flanks. They were (hopefully) out of small arms range and able to catch enemy infantry attacks in a cross fire. I suppose that also allowed enemy tanks to be engaged on the thinner side armor. 

Heer doctrine also stressed firing at the turret ring of tanks with armor too heavy to be penetrated. I think American Bradley IFV gunners did the same thing when engaging Iraqi tanks at close range during 1991.


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## tyrodtom (Oct 27, 2011)

kettbo said:


> Rear of tank not heavily armored nor is the back deck nor turret roof. 20mm adequate, multiple 20mm more than adequate until later vehicles were armored better. Then 30mm a more realistic weapon.
> Some vehicles blow up after catching fire due to engine area hits. Fuel then was usually gas except some Shermans used by the UK (and USMC in the Pacific) and the T-34 and later Soviet tanks. Maybe the lighter tanks taking direct hits turret roof could blow due to ammo hits. Even the Tigers and Panthers were vulnerable to rear deck engine grate hits. You can see mods of plates fitted above the grates to reduce this, late 44.
> Open hatches are not proof against anything
> Rockets are pretty nasty things though not particularly accurate.
> ...




If the explosion has enough power to lift the many tons of a turret off it's turret ring, you're not going to see any reconizable human remains in a photograph. We're talking about a trememdous overpressure to lift a turret, it would turn a body to mush.


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## davebender (Oct 27, 2011)

_In the evening, we returned to our old positions. There we received the mission to occupy the village behind that high ground the next morning. We were thus supposed to open the way for an infantry regiment. Two more tanks and three 20mm quad Flak guns were attached to me at darkness. The latter proved themselves magnificently in action against ground targets._
Otto Carius


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## vanir (Oct 27, 2011)

Shaped charges were pretty rudimentary but British and Soviet anti-armour rockets were specially made capable of penetrating 150-300mm of case hardened armour at any angle on a direct hit, upwards. I mean seriously the really big leap made in anti-armour weaponry was made right there in WW2, things like the modern Maverick just refined it. There's a whole catalogue of man-portable and aerial shaped charge warheads with terrific antitank performance comparable to modern weaponry. We just do the same thing better now, not so much a different thing.
Fire a volley, if you hit, guaranteed there aint nothing left of any German superpanzer, no way.


Oh Rechlin testing does put the muzzle energy of a 2cm FlaK shell (assuming a MG151 variation, my German isn't good) up around 3 tons. I guess I'd feel nervous in an old tank. 3cm FlaK is around 14.3 tons though, yeah that would be more disconcerting.


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## davebender (Oct 27, 2011)

*Muzzle Energy.*
An introduction to collecting 20 mm cannon cartridges The 20 mm automatic cannon first saw service during World War 1 but achieved its
24,000 joules. 20mm x 80mmRB. MG-FF aircraft cannon. 
29,000 joules. 20mm x 82mm cartridge. MG151/20 aircraft cannon.
47 to 60,000 joules. 20mm x 138mmB cartridge. Most WWII light flak such as flakverling.
84,400 joules. 20mm x 139mm cartridge. Modern day NATO cannon such as German Rh202.


An introduction to collecting 30 mm cannon ammunition
42,100 joules. 30mm x 90mmRB cartridge. Mk108 aircraft cannon.
131,500 to 163,600 joules. 30mm x 184mmB cartridge. Mk101 and Mk103 aircraft cannon.
207,000 joules. 30mm x 173mm cartridge. Modern day GAU-8/A cannon employed by A-10 aircraft.

As you can see the cartridge fired by most WWII era German 20mm flak was roughly twice as powerful as as the Mg151/20 cartridge. That's why the Heer rarely used the lightweight and fast firing Mg151/20 cannon.

It's easy to see why a 30mm Mk103 cannon with state of the art ammunition (i.e. uranium) was so capable. Muzzle energy was about 75% of the modern day A-10 cannon.


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## Shortround6 (Oct 27, 2011)

davebender said:


> 207,000 joules. 30mm x 173mm cartridge. Modern day GAU-8/A cannon employed by A-10 aircraft.
> 
> It's easy to see why a 30mm Mk103 cannon with state of the art ammunition (i.e. uranium) was so capable. Muzzle energy was about 75% of the modern day A-10 cannon.



And that is also the reason why the notion of "chewing through" armor with fast firing small cannons is pretty much bunk. Muzzle energy of a Standard German 50mm anti-tank round was 652,000 joules. the APCR round had 900,000 joules. British 6pdr had 989,000 joules. You would need about 4 rounds of the 30mm ammo to hit within 27mm of each other (center to center) to equal the energy application the 6pdr round. Even tighter to equal the German 50mm APCR round. the chances of getting enough 20mm rounds into a small enough area are getting astronomical. 10-14 rounds landing within 30mm center to center to equal regular ammo? The German 50mm was marginal against many Russian tanks using regular ammunition.


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## psteel (Oct 27, 2011)

Multiple hits on armored plate will progressively weaken the plate. They don't have to be within 3/4 of a projectile diameter of each other.


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## parsifal (Oct 27, 2011)

The A-10s cannon has a cyclic rate of about 6000 rpm does it not. At that rate you might get a grouping as required. At the ROF applicable to a single barrled cannon....about 800-1000 rpm, it would be difficult to achieve the necessary gropuping to achieve penetration.

I remember also reading somewhere that A-10s dont aim to penetrate the deck armour of enemy tanks. They aim mostly to disable the tank by taking out the tracks do they not?????


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## davebender (Oct 28, 2011)

I wonder if the composition of modern day laminate tank armor has something to do with it. The ceramic layers must be brittle. Multiple hits might smash it up a layer at a time.


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## Shortround6 (Oct 28, 2011)

psteel said:


> Multiple hits on armored plate will progressively weaken the plate. They don't have to be within 3/4 of a projectile diameter of each other.



Maybe not but but they do have to be close. hits 15cm to 100cm away aren't going to get much if any benefit from previous hits. For WW II use you are talking a mechanical accuracy ( accuracy of the gun and ammo bolted to a substantial mount) better than most of the sniper rifles of the time could achieve. 

A flak Veirling has got a real problem with 4 different barrels. It may stand a better chance of a "golden BB" going through a vision port or joint than "chewing through" the same spot. 

Brittle armor can crack from multiple hits in a small area but depending on your opponent to make bad armor is bad planning for weapons procurement.


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## davebender (Oct 28, 2011)

There were a lot more things on the WWII battlefield then T-34 tanks.

*Soviet Armored Vehicle Production.*
Soviet combat vehicle production during World War II - Wikipedia, the free encyclopedia
1,717 x T-26 light tanks.
780 x BT-7 light tanks.
896 x T-40 light tanks.
75 x T-50 light tanks.
5,773 x T-60 light tanks.
8,231 x T-70 light tanks. 
101 x ZiS-30 SP guns.
12,054 x Su-76 SP guns. Second most numerous Soviet armored vehicle. Open top makes it especially vulnerable to automatic weapons fire.
1,400 x Ba-10 armored cars.
9,110 Ba-64 armored cars.

Trucks, artillery pieces, artillery horse teams, artillery tractors and horse drawn wagons numbering in the hundreds of thousands.

VVS CAS aircraft numbering in the 10s of thousands.

Soviet infantry numbering in the millions.


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## vanir (Oct 28, 2011)

I'm at some other aviation websites with ex-military pilots and one has commented at length on how the A-10 does an anti-armour attack, even posted the USAF documented guidelines for taking down a T-72 with the GAU cannon, diagrams and all. They aim at the hull area which is where the wheels/tracks are. Armour is thinnest here. WW2 doctrine however would be the rear/upper plates and the attack angle much steeper.

cyclic rate on the gun is 2100rpm/c. It has a switch for 4200rpm/c but it was troublesome and unnecessary at this speed so was disabled in the 80s update.
cyclic rate for wartime single barrel 3cm guns with any kind of anti-armour velocity is about 350rpm/c in practise. The MK213/3cm was projected for 1200rpm/c and this was achieved in the DEFA copy, which is a rather direct copy of German wartime blueprints. Muzzle energy is up around a Mk103 too, but in a second generation version I think that went into production in the 60s. The original one, ex-German was slightly more powerful than a Mk108 from memory. Tony William's site will have the correct figures.

The real nasty one was the MG213, 1600rpm/c. Even at MG151 shell energy that's a lot of damage.


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## psteel (Oct 28, 2011)

Shortround6 said:


> Maybe not but but they do have to be close. hits 15cm to 100cm away aren't going to get much if any benefit from previous hits. For WW II use you are talking a mechanical accuracy ( accuracy of the gun and ammo bolted to a substantial mount) better than most of the sniper rifles of the time could achieve.
> 
> A flak Veirling has got a real problem with 4 different barrels. It may stand a better chance of a "golden BB" going through a vision port or joint than "chewing through" the same spot.
> 
> Brittle armor can crack from multiple hits in a small area but depending on your opponent to make bad armor is bad planning for weapons procurement.


 
Accually they don't have to be close. Pretty much anywere on the plate will do. Modern ballistics are emphatic...one shot per target plate! Doesn't matter if its a shaped charge , APFSDS APDS or APC etc only one shot per target plate or else it skews the data.


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## davebender (Oct 28, 2011)

I agree. 

Schützenpanzer Lang HS.30 - Wikipedia, the free encyclopedia
Why didn't the Heer adopt this weapon for the Schützenpanzer Lang HS.30 during the 1950s rather then purchasing the French made Hs.820 autocannon?


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## Shortround6 (Oct 28, 2011)

davebender said:


> There were a lot more things on the WWII battlefield then T-34 tanks.
> 
> *Soviet Armored Vehicle Production.*
> Soviet combat vehicle production during World War II - Wikipedia, the free encyclopedia
> ...



I am not the one who brought up the idea of "chewing" through armor. You might also want to do a bit of real reading instead of relying on Wikipedia. 

The Flakvierling was first being introduced when quite few of the vehicles on your list were being phased out of production. 

The Flakvierling weighed more in action ( and a lot more in tow) than a 7.cm Pak 40 anti-tank gun, it needed a bigger crew and was larger and harder to dig in or hide. 

Siting you AA guns well forward to act as ground guns means they are NOT doing a proper job of air defense.


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## vanir (Oct 29, 2011)

davebender said:


> I agree.
> 
> Schützenpanzer Lang HS.30 - Wikipedia, the free encyclopedia
> Why didn't the Heer adopt this weapon for the Schützenpanzer Lang HS.30 during the 1950s rather then purchasing the French made Hs.820 autocannon?



Believe it or not I smell the distinct odour of political correctness in this decision. The world was still pretty sore on the Germans but the military threat had become the Soviets. This AFV was a Swiss design, by a French company, with a British engine, to be made and equipped in Germany. I think if you whipped out a German wartime gun design on it, you might have seen it in newspapers headlines like, "NATO adopts tools of the devil!"

I think they managed to afford such political luxuries because the IFV had fallen into the background since the defeat of Axis forces and establishment of the Iron Curtain, because it wasn't predominant in US doctrine and the industrial strength of the US clearly led NATO doctrine right from the beginning. The military surplus in the US in 1950 was just ridiculous, you could've laid waste to the planet the old fashioned conventional way with it.

So European tactical doctrine was quickly falling into the background at NATO fronts like Germany. The closest competitors in the IFV stakes at the time used HMG. The Soviets were only just beginning to conceive their infamous motorised rifle battalions, so didn't have that much comparatively in IFV (just tanks and SPG, and of course gazillions of towed artillery). 

I think it was a case of the public mind at a time of continuing tensions in Europe. They could've put an Aden in it, it's an MG213 copy too. But people would start complaining, wondering if the Allies of WW2 had gone Nietzchean in the postwar environment with the Russians, and in fighting Germany had become the monster when the abyss had looked back into them.
The general public can be a bit like that, and if they get concerted enough they can shut down a military, or sack a government.


hey just reading further down the article, it even mentions there was a media controversy as it was.


> These investigations revealed that key personnel associated with the procurement of the SPz 12-3 had accepted bribes as high as 2.3 million Deutschmarks (DM). Other witnesses asserted the Christian Democratic Union political party received campaign donations totaling some 50 million DM as a result of its support for SPz 12-3 procurement.



I'd say right about then they were saying to themselves, "Gee glad we didn't put that Aden on it."


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## Shortround6 (Oct 29, 2011)

A few reasons they didn't put the 213C were mentioned earlier in the thread. Like cooling the barrel of a high cycle rate gun. Another is wither the 213 was _really_ ready for production, even if the French and British versions were (only took them how many years to get it into service?) another is the feed. Fixed gun (in aircraft) may be easier to feed than a gun the moves in relation to the ammo supply. As far as using the Aden instead of the HS 82) there might be problems with ammo capacity, trajectory, and even penetration. The early Aden gun used a shorter cartridge case and fired a 273gram shell at 604 m/s


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## davebender (Oct 29, 2011)

Heck let's go all the way.

Purchase PT-76 light tank chassis from the Soviet Union. It's about the right size.

The IFV hull would be fabricated in newly communist China.

The turret and MG213 main gun will be built in West Germany.


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## psteel (Oct 29, 2011)

THe Hs 820 had much higher muzzle velocity than the Aden plus a higher rate of fire. Combined for a ICV this meant it could more easily be used and trained in its intended role as a multi purpose fire support weapon for the Panzer Grenadier units.

During the cold war most of use felt it would be better having the Germans on our side, besides that was decades and alliances and allegiances had clearly changed dramatically.


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## davebender (Oct 29, 2011)

But not higher then the 20mm MG213. The German revolver cannon also had a considerably faster rate of fire.


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## psteel (Oct 31, 2011)

davebender said:


> But not higher then the 20mm MG213. The German revolver cannon also had a considerably faster rate of fire.



This site reports the Hs 820 could do 1000rpm and 1100m/s

Hispano-Suiza HS.820 - Wikipedia, the free encyclopedia

This site reports the Mg 213 could do 1200rpm and 1000m/s.

20 mm MG 213/20 (Maschinengewehr 213/20)

So Hs-820 has higher muzzle velocity while the MG213 has greater rate of fire.


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## vanir (Oct 31, 2011)

to be honest those quoted figures are close enough to be superfluous in the field.




and shortrounds answer is much better than mine, but I'll still go with could a bit of both.


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## davebender (Oct 31, 2011)

> Through an unbelievable series of events which will not be discussed in this report, the Army got the Hispano-Suiza 820 (M139) gun and the ammunition that went with it. (Perhaps the Army didn't know exactly what they wanted, but this certainly was not it.)
> 
> The Hispano-Suiza gun was never known for its reliability, regardless of the size in which it was built. Also it had to be kept clean and well lubricated, a difficult requirement in dusty or sandy environments.



Not exactly a ringing endorsement of the Hs.820 cannon from the USAF Armament Laboratory.


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## psteel (Oct 31, 2011)

vanir said:


> to be honest those quoted figures are close enough to be superfluous in the field.
> 
> 
> 
> ...



My point exactly..... '6 of one 1/2 dozen of the other'


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## vanir (Oct 31, 2011)

I didn't even look up the Hispano gun, the way it was first mentioned I just assumed it would have a significant drop in performance over a revolver-cannon.

Still, I suspect a revolver cannon would have a higher sustained fire performance. DEFA/Aden are common designs, and DEFA have pretty good barrel life. It's Soviet guns that have shocking barrel life, do you reckon it's the metallurgy or the guns? I'm thinking of the Gsh-301, it can fire what, 500rds before a barrel change? Must be one tight chambering and strong rifle, probably super accurate I guess.


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## psteel (Nov 1, 2011)

French 20 mm/90 GIAT M693 and 20 mm/73 GIAT M621

Hs 820 Barrel life is 16,000 rounds compared to 9,000 for the Oerlikon competitor.

Britain, Switzerland and USA 20 mm/70 (0.79") Oerlikon Marks 1, 2, 3 and 4

Mk 16 20mm gun was a derivative of the earlier Hs 404 gun got only 6500 barrel life.

The Naval Institute guide to world ... - Norman Friedman - Google Books

According to this site the ADEN/DEFA 30mm gun was only rated 5000 rounds, while it confirms that Russia guns were only about 2000 rounds.


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## davebender (Nov 1, 2011)

Sounds durable enough. That doesn't mean it was reliable under typical combat conditions. Unfortunately the USAF Armament Laboratory report did not provide a lot of specifics other then noting the Hs.820 cannon performed poorly in dusty conditions. 

I've spent 14 years in the U.S. Army. Dust is the norm for vehicles of any type operating off road.


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## psteel (Nov 2, 2011)

The Aden gun was twice the mass of the Hs 820 gun and burned through barrels at three times the rate, which makes it a deal breaker. From the POV of purchasing a fire support weapon for the SPz 12-3, Aden was just too big and probably too expensive. It certainly would have been if it chews through barrels at 3-4 times the rate. Hs 820 and follow on Rh 202 were ideal for German Panzer grenadier doctrine and certainly more cost effective from a coldwar POV.


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## parsifal (Nov 2, 2011)

All these weapons seem remarkably similar except for barrle wear and, i guess, reliability. Except if cost is no object, this has to be a major point....those that wear parts out the quickest are the least desirable, surely


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## davebender (Nov 3, 2011)

I think the Hs.820 was just an interim weapon until Germany regained the ability to manufacture munitions. The Rh.202 is exactly what the Heer wanted, which is why it has remained in service so long. 

On paper the WWII era MG301 prototype had performance similiar to the Rh.202. Did the MG301 serve as a starting point for development of the Rh.202 cannon?


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## Shortround6 (Nov 5, 2011)

Barrel wear is largely dependent on cooling. The Hotter the barrel the faster it "wears". Actually each cartridge/round is a cutting torch that lasts for micro seconds. A gun with air flowing over it at 400-700mph ( aircraft gun) can fire longer bursts than a ground gun and fire closer spaced bursts than a ground gun. 

You could probably wreck any of the mentioned barrels in just a few hundred rounds if they were fired in one long burst with little or no airflow over the barrel. Even US aircraft .50s had some rather sever restrictions on firing and cooling limits in order to reach "book" barrel life figures.


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## vanir (Nov 6, 2011)

Making some good sense there Shortround, didn't even think about cooling. Of course the Aden and similar are aero guns, they probably weigh half as much again adapted for ground use.

Also, Shortround, is this a reason aero gun barrels tend to be lighter than their ground based equivalent? I always thought it was just a weight thing...but then some pretty weighty guns are still installed.


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## davebender (Nov 6, 2011)

The Rh.202 cannon is a ground based weapon that fires 1,000 rounds per minute. How do they cope with barrel heat?


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## Shortround6 (Nov 6, 2011)

A heavy barrel (28KG) and short bursts. Most guns will stand 2-3 second bursts or even several in a row. What they won't stand is 5-10 second bursts in rapid succession. Some modern cannon may use chrome lined bores or even stelite linings. 
If the "practical" rate of fire is under 200rpm due to cooling issues then trying to use high cycle rate guns (aircraft type) for ground support really doesn't buy much. High cycle rate is useful for fleeting targets like aircraft to increase hit probability for the few seconds the target is within firing range of the ground gun but for use against ground targets high cycle rates don't have much advantage.


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## psteel (Nov 6, 2011)

According to the 'Rheinmetal hand book on weaponary', most firing sequences are patterned on the French method at 12 bursts of fire followed by 2 second cool down plus another 12 burst pattern and another cool down period.


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## davebender (Nov 6, 2011)

How many rounds in a burst? With a rate of fire that high it must be at least 10.


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## tyrodtom (Nov 6, 2011)

I think they mean a 12 round burst, followed by a 2 second cool down. Translations can be confusing sometimes.


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## vanir (Nov 7, 2011)

I naturally assumed IFV were initially largely AAA armed anyway, I mean anybody else using IFV in the 50s had HMG on board, a markedly dual purpose armament.
I should think at this point the IFV was less an assault AFV like a StuG or a tank-killer (at least until AT-missiles were widespread), it was more like a scout with some light-AAA or infantry support capability.

Later on IFV continued with dual purpose armaments, NATO tended to go with things like DP Bofors whilst the Soviets went AT-missiles and lightened field guns on theirs with coaxial HMG or light, rapid cannon, obviously the motorised rifle brigade utilised different combat doctrine and deployment to the west. Later Soviet IFV are more like lightened MBT amphibs than IFV, the whole fleet is fully NBC sealed too.

The later Marder II SPG is an AAA complex. Marder was originally an AT-field gun. I was just naturally thinking this general shift in thinking represented NATO influence of IFV becoming dual purpose AFV with strong AAA leanings, rather than infantry assault guns with an anti-tank emphasis.


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## Shortround6 (Nov 7, 2011)

During the 1950s a 20mm gun on a IFV was hot stuff. It wasn't meant to be anti-tank but anti-APC. With a number of armies still using large numbers of essentially armored trucks, or tracked armored boxes with 1/2in (12mm) armor a 20mm gun could take out quite a number of battle field ground targets when you add the vehicles to the fire support targets like MG positions and such. 
AA capability was limited. May work against helicopters but most mounts didn't have the traverse or elevating speeds needed to track jet attack aircraft, while the Marder IFV does it's predecessors used manual turrets. Anything is better than nothing but the US .50 cal MG AA capability was pretty dismal in WW II. It may have scared off a number of attackers but the number of rounds fired vs the number of aircraft brought down would have any accountant looking for another solution. There is a huge difference in the effectiveness of a power operated quad .50 and four separate .50s on pintle or ring mounts.


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## davebender (Nov 7, 2011)

Or anti-infantry as the flakvierling was employed during WWII. 20mm mine shells have a small casualty radius but the high rate of fire allows you to quickly smother an entire enemy infantry squad. The 20mm M197 gatling gun employed on some Cobra gunships would have a similiar effect vs infantry.


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## futuredogfight (Nov 7, 2011)

They are highly effective, thats why. BTW 50th post w00t!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


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