Designing an Italian tank tree for WOT: Part 2 - Completing the tree using licensed foreign components and designs

Disclaimer: the contents of this article are highly speculative and while the discussed components are historical there is no proof of actual plans for tank usage.

In part 1 we discussed the historical WWII Italian tank development, however this leads us to a limited tree, covering roughly half of the needed tanks for a proper WOT tree.
This of course is due to the fact that the Italian industry planned its designs only on what it could be produced with minimal investment and relatively in short time.

This does not mean that the Italian industry was technologically limited to what it produced but rather to the fact that the army was chronically short on funds as the navy and air force took the lion share of the defense budget, while the army had to rely on second hand research and often WWI vintage equipment.
Even the vaunted 90/53 was in fact a navy development adapted to land use (along with other guns like the 75/46), but this doesn't mean that advanced components weren't produced or at least reached prototype stage in Italy.

This article will explore production and prototype components used or planned in Italy during WWII, in addition to post war licensed vehicles modified by the Italian army.
The overall picture will define what tank development could have been had the army received more support and thus followed more aggressive licensing and development.

 

Tier I		(L) L5
Tier II	(M) M13/40	(L) L6/40	(TD) CDR M12
Tier III	(H) P 75	(M) M15/42	(TD) Semovente M41
Tier IV	(H) P 26/40	(M) M16/43 Sahariano	(TD) Semovente M43
Tier V	(H) P43		(TD) Semovente 90/53
Tier VI	(H) P43 Bis		(TD) Semovente 120/44
Tier VII	(M) M45/44
Tier VIII	(M) M52/45
Tier IX	Patton OTO
Tier X	Leopard Centauro

Historical
Based on WWII license - speculative compotents
Post WWII license - historical components


The need for a sharper edge: technological licenses

Italian military industry developed strong foreign partnerships between late 19th century and early 20th, with partnerships such as Vickers-Terni and Armstrong, while after WWI smaller weapon licensing continued with Czech and Austrian partners.

During WWII technological collaboration with Germany was of course sought, with the most renown products being the licensed DB 600 series engines, which powered the best Italian airplanes of the war. Maybach engine licenses were given in early 1943, thus failing to make an impact.

In the tank field, Skoda T21 was evaluated, while production of Panzer III (for which Germans were ready to give 160% of resources for each tank made!) and especially the Panther was seriously taken in consideration and had war taken a lesser toll on the military-industrial complex it is extremely likely we would have seen localized versions of the Panther strolling in the battlefield, something that was seen favorably by the German high command:

Italian high command on the other side considered both local manufacturing of the tank and importing the parts for local assembly, projects stopped by the allied bombing campaigns and ultimately by the invasion of Italian soil.

Had the Panther been put in production, the Italian army would have had a tank able to carry its most powerful guns in a mobile and relatively well armored platform superior to even the P43, it's most advanced tank project.

Tier VII: M45/44

Fiat-Ansaldo received Panther plans in early 1943 and it's likely that production set-up would have made production start in 1944.
It should be noted that what Italy received in license was just the MAN plans and production data and not other components, as for example they had to separately license the engine:

This means that rather than setting up yet another production line it's extremely likely native components would have preferred.
Engine wise, other than the still in design 700 HP SPA 343 (which is likely an attempt to copy the MB HL 230) the only engines powerful enough to push such an heavy tank were airplane ones, precisely the Daimler Benz 600 series licensed copies.

This wouldn't be new to the Panther, as the German themselves discussed implementing the DB 601 derived MB 507 engine as measure to deal with shortages of Maybach engines.
The closest Italian relative would be the Alfa Romeo RA 1000 RC.41 engine, a slightly less powerful (due to lesser quality material, although sturdier) copy of DB 601.

Using the German conversion as indication, we could estimate that mounted on a tank this engine would deliver something around 750-780 HP, slightly better than the HL 230 in terms of sheer power but at the price of a much bigger engine.

On the firepower side, given that there is nothing on sources pointing out towards a Rheinmetall license we can easily speculate that the Panther would house Italy's most powerful AT gun in production, the 90mm L/53.
Again, a similar caliber was already proposed on Panther's turret, specifically the 88mm L/71:

Translated in World Of Tanks gameplay, the Italian Panther would be more agile (17,3 HP/ton VS 15,5), use a more powerful cannon but likely suffer on long range accuracy and armor penetration, changing the tank's role from that of a long range sniper to mobile medium range support.

Tier VIII: M52/45

Panther license also covered the Panther II plans, which in Germany didn't get beyond prototype stage and would likely merge with the E-50 project.

As Italy didn't have heavy tanks like the Tiger it's likely that the Panther II chassis would have been chosen to face soviet heavy tanks in 1945 and beyond.

To push such an heavy beast it's likely that an aero engine would have been chosen again instead of the HL 230 as Italian doctrine called for mobility (and they saw slower design such as the otherwise formidable KV as unpractical), again a DB 600 series copy.

The Fiat 1050 RC.58I was just coming out of prototype stage in 1943 and it was a pretty decent DB 605 copy, which after conversion would likely have given around 850 HP (for a pretty decent 16,3 HP/ton), just enough to perform properly on hilly terrain but still a good edge against IS tanks.

 

On the firepower side things are however a bit more complicated as the 90mm L/53 wouldn't cut it anymore against an IS-2 or IS-3 and a longer 90mm cannon was at best at the paper stage.
The 90mm L/71 or L/74 would have been perfect (although a bit heavy for the turret) but its development went beyond paper stage only after the war, while anything from the navy is simply too heavy and cumbersome for a turreted tank.

Looking at German proposals there is however one solution left that would still realistically fit inside a turret and powerful enough to scare heavy tanks: The sturmpanther.

Using such a short gun would mean accuracy going to hell, however no WWII tank would find a 15cm shell as something that armor could shrug off, barring perhaps super-heavy tanks such as the Maus.

A similar gun in army service was the Cannone da 149/13, a Czech artillery piece adopted by the Italian army and used both as short range artillery and anti tank gun thanks to specifically developed EPS (shaped charge) ammunition:

The gun was slightly heavier (and shot at higher MV) than the SIG 33 based STUH43, however still within turret ring capacity as it was lighter than the German 88mm L/71.

 In WOT terms we'd again have a tank poorly suited for long range sniping but able to deliver a devastating (but slow firing and inaccurate) punch at close ranges and with enough agility to evade punishment against unprepared heavy tanks.

While powerful however the design would suffer against enemy medium tanks as it lacks the speed to escape from them and the rate of fire to fight them off.

Tier IX: Patton OTO

In mid 1960s the Italian army sought to upgrade and modernize their M47 Patton fleet.

Several proposals were made, the most remarkable of which included using either M60 or Leopard I engines.

OTO Melara created a tank upgrade  using the Royal Ordnance L7 gun along with M60s Continental AVDS 1750 engine and several minor modifications to hull, electric systems and transmission.

Historically this tank (which was planned as "short term solution") could have served as a nice gap between American designs and the Leopard European tank, although it ultimately never reached production stage.

Tier X: Leopard Centauro 

Not much is known about this proposal, which entailed an automatic loading system for the L7 cannon on a Leopard I chassis, while the rest is assumed to stay pretty much identical.
This would have helped reducing crew requirements in a similar way as contemporary Soviet designs, although bringing with it the same disadvantages.

While not an unique tank in World of tanks, it would offer different play style from the original Leopard I.

Designing an Italian tank tree for WOT: Part 1 - Main historical WWII designs

Italian tanks have been considered several times for World of Tanks, however their introduction poses several challenges which will be covered in this article series.
Aside from historical hurdles, many tanks have a performance that falls in between that of WOT tiers, making them challenging to balance.

A strictly historical tree provides the basis for further developments, however it highlights the sheer lack of late war Italian projects, especially as even the most advanced tanks were designed with a priority towards ease of manufacture rather than battlefield superiority.

Italian industry did not lack the technical know-how for manufacture of more advanced components like welded armor or torsion bars, however Italian armored forces always had a lower priority in resource allocation than either navy or air force, resulting in most designs hampered by cost cutting measures, which for example meant assembly lines never retooled for casting or welding (both reserved for the navy) and indigenous weapon designs were more often than not little more than unlicensed copies or adaptations of British (Vickers-Terni) and Czech (or captured WWI austro-hungarian) designs, concealed by keeping an obsolete length measurement system for barrels.

Italian tank doctrine also favored lighter tank designs, with heavy tanks viewed as unreliable and hard to drive (Soviet KV tanks failed to impress Italian evaluators, however T-34 was viewed as a design to be copied), resulting in local tank classes that were in the same weight range as a lighter class in foreign designation, especially as the P43 Bis was the heaviest peaking at a mere 35 tonnes.

Classification: (L) for light, (M) for medium, (H) for heavy, (TD) for tank destroyer, (A) for Artillery

 

Tier I		(L) L5
Tier II	(M) M13/40	(L) L6/40	(TD) CDR M12
Tier III	(H) P 75	(M) M15/42	(TD) Semovente M41
Tier IV	(H) P 26/40	(M) M16/43 Sahariano	(TD) Semovente M43
Tier V	(H) P43		(TD) Semovente 90/53
Tier VI	(H) P43 Bis		(TD) Semovente 120/44
Tier VII
Tier VIII
Tier IX
Tier X

 Tier I: Ansaldo L5

 

The L5 was a 5 ton light tank developed from the L3 series tankettes, which in turn were an evolution of the Carden-Loyd tankette.

Experiments for fitting a turret on top of an L3 tankette started in 1936, with the first trials equipped with twin 8mm Mgs in the turret and later on swapped so that the gun was in the turret and Mgs in the hull.

This design was called “Carro d'assalto 5t”, L5 using the 1940 designation, armed with a 37mm L/26 cannon.

Later developments eventually ended up in the M6 prototype, which went on to become the L6/40.

Technical data:

Weight: 5.8 tonnes

Armor: Front: 13,5mm, side 8,5mm read 13,5mm

L:3,15m W: 1,4m H: approx 1,85-2,15m depending on the turret.

Engine: CV 3-005, petrol 43HP

Ground Pressure: approx 1kg/sq cm

Top speed: 42 km/h is the theoretical speed of both the parent L3 and the later L6, however the much worse HP/ton ratio means lower speed is very likely

Base gun: Cannone da 37mm L/26
Improved gun: 13,2mm Breda 1931 (or 12,7mm Breda/Safat),

 Tier II: M13/40

Rather than trying to fit the M11/39 which would have problems being competitive due to its casemate design and anemic firepower, the M13/40 provides a competitive medium tank design able to go toe to toe with early panzers and Vickers 6 ton derivatives that populates low tiers.
As World of Tanks requires you to upgrade your tank components (often referred as "grinding"), we'll use M11/39 parts for this process.

Fully developed, M13/40 would have decent armor for its tier, not so great agility (unless given M14/41 engine) but with the 47/32 being a killer gun for its tier, able to deal with pretty much anything it meets:

Technical data:

Weight: 13 tonnes
Armor: front 30mm/11° sides and rear 25mm
L: 4,91m W: 2,2m H: 2,37m
Ground Pressure: 0,93 kg/sq cm
Top speed: 32 km/h

Base components from M11/39:
Gun: Cannone da 37mm L/40
Engine: SPA 8T, 105 HP Diesel

M 13/40 configuration:
Gun: Cannone da 47mm L/32
Engine: SPA 8TM40, 125 HP (potentially upgradeable to SPA 15TM41, 145 HP Diesel)


 Tier II: L6/40

 The most advanced Italian light tank in 1940, the L6/40 was a pretty good cavarly tank at its introduction, agile, armed and armored not unlike similar light tank design of the same period.
Its power to weight ratio would limit its performance in hilly terrain while tiny side armor would put it at disadvantage when brawling, however the 20mm Breda will give pause to anything not armored enough to absorb the hits with impunity.

Technical data:

Weight:6,8 tonnes
Armor: front 30mm, sides and rear 14,5mm
L: 3,78m W: 1,92m H: 2,03m
Ground Pressure: 0,44 kg/sq cm
Top speed:42 km/h

Base components:
Gun: Cannone da 37mm L/26
Engine: SPA 18VT 67HP

Improved gun: 20mm L/65 Breda
Improved engine: SPA 18D 70HP


Tier II: M12

Although not technically a tank destroyer, the M12 was the "breakthrough tank" concept that eventually evolved in the M11/39.

Conceived for mountain warfare it was reasonably protected and armed with the same howitzer as the mythical Fiat 2000, it could serve as starting point for the semovente line, as L3 and L6 based designs unfortunately don't have suitable gun choices.

All in all, in WOT it would play like a more agile but less armored T18, preying on poorly protected targets using mostly high explosive shells.

Technical data:

Weight: 12 tonnes
Armor: Front  30mm, Sides and rear 14,5mm
L: 4,73m W:2,18m H: 1,9m approximately
Ground Pressure:approx 0,8 kg/sq cm
Top speed: 33km/h
Engine: SPA 8T, 105 HP Diesel

Base Gun: Cannone da 37mm L/40
Improved Gun: Cannone da 65mm L/17 (AP ammo was actually available, unknown effectiveness)

 Tier III: P75

The P75 was the earliest draft of a WWII Italian heavy tank.

Clearly inspired by the German Neubaufahrzeug, it was a massive tank although under-armed and under-armored just like similar designs.

Technical data:

Weight: 30.5 tonnes
Armor: 40mm front, 20mm sides and rear
L: 7,53m W:3m H: 3,5m
Top speed: 32 km/h

Base Engine: SPA Prototipo 420 HP
Improved Engine: SPA P. Celere 480 HP

Gun: Cannone da 75mm L/18

Tier III: M15/42

The most advanced Italian serially produced medium tank, the M15/42 is perhaps almost too strong compared to its WOT peers.
Strong frontal armor and a pretty good gun for its tier makes it a powerful opponent, although high ground pressure and not so stellar power to weight ratio weakens its performance on slopes and soft terrain, while the two man turret means that target acquisition and rate of fire would suffer as well.


Technical data:

Weight: 15,5 tonnes
Armor: Front 42mm, sides and rear 14,5mm
L: 5,04m W:2,23m H: 2,38m
Top speed: 40 km/h
Ground Pressure: 0,96 kg/sq cm
Base Engine: SPA 15TM41, 145 HP Diesel
Improved Engine:  SPA 15TBM42, 192HP

Base Gun: Cannone da 47mm L/32
Improved Gun: Cannone da 47mm L/40

Tier III: Semovente M41

 

A source of nasty surprises for the british in Africa, the Semovente M41 is usually known as Semovente da 75/18, from its main production cannon.
It was the only vehicle able to pierce all allied armor in the Italian army at its introduction thanks to its powerful but extremely scarce "Effetto Pronto" hollow charge rounds.
The 75/32 cannon was also fitted to the chassis in very limited series, giving it an upgraded gun able to keep pace with its main targets although not as powerful as the ones on the German Marder.

Technical data:

Weight: 14 tonnes
Armor:  front 30mm/11° sides and rear 25mm
L: 4,9m W: 2,3m H: 1,9m
Top speed: 31km/h
Base Engine: SPA 8TM40, 125 HP
Improved Engine: SPA 15TM41, 145 HP Diesel

Base Gun: Cannone da 75mm L/18
Improved Gun: Cannone da 75mm L/32

 Tier IV: P26/40

The most powerful tank fielded by the WWII Italian army, the P26/40 would be extremely powerful for its level, perhaps almost too strong, giving the British Matilda a worthy rival.
A combination of strong frontal armor, good gun and decent speed makes it very strong against same tier but the limited penetration greatly hampers it against armored designs.
Historically the design suffered from a lack of engine production, which led the Germans tinker with it and planning the use of spare Maybach HL 100 engines.

Technical data:

Weight: 26 tonnes
Armor: 50mm front, 40mm sides and rear
L: 5,7m W: 2,75m H: 2,5m
Ground Pressure: 0,94 kg/sq cm
Top speed: 40 km/h
Base Engine: MB HL 100 300 HP
Improved Engine: SPA 342 330 HP (Diesel)

Base Gun: Cannone da 75mm L/18
Improved Guns: Cannone da 47mm L/40, Cannone da 75mm L/34

Tier IV: M43 Sahariano

Perhaps the most advanced Italian WWII tank prototype, the Carro Medio Celere M43 was a direct answer to the british cruiser tanks and an innovative design for the Italian army.
While not an improvement on armor or armament from the M15, the ability of reaching up to 60 kilometers per hour will still guarantee a very dynamic and fun tank for flanking actions.

Technical data:

Weight: 13,5 tonnes
Armor: 30mm front, 25mm sides and rear
L: 5,8m W:2,8m H:2m
Top speed: 60 km/h

Gun: Cannone da 47mm L/40

Base engine: SPA 15TBM42, 192HP
Improved Engine: SPA 18TBM43, 275 HP

Tier IV: Semovente M43

Affectionately called the "Bassotto"(or dachshund), the M43 resembles the German STUG III, both in shape and effectiveness. Armed and armored adequately to deal with any allied tank it faced, there were never enough tanks available due to a very short production run.

Technical data:

Weight: 16 tonnes
Armor: 70mm front, 45mm casemate sides, 25mm hull sides and rear
L: 5,07m, W: 2,4m, H: 1,74m
Top speed: 38 km/h

Base gun: Cannone da 75mm L/34
Improved guns: Cannone da 75mm L/46, cannone da 105mm L/25

Base engine: SPA 15TM41, 145 HP Diesel
Improved engine: SPA 15TBM42, 192HP

Tier V: P30/43

Note: P43 is the middle design, compared to P26 and Panther

A more advanced design and pretty close to the limit of the 1943 Italian industry, the P43 was considered by the Germans  an imitation of their own Panther as it had a similar armor layout and power to weight ratio, although with a firepower comparable to late model Panzer IV.

The design reached mock-up stage and RSI under German control considered actually producing it but allied bombing and logistical issues prevented any follow-up on the plan.

Technical data:

Weight: 30 tonnes

Armor: 80mm front, 50mm sides and rear (Spielberger, needs further checks)
Base Engine: SPA 342 330 HP (Diesel)

Improved Engine:  SPA 343 420 HP

Base Gun: Cannone da 75mm L/34

Improved Guns: Cannone da 75mm L/46

Tier V: Semovente 90/53

The most powerful production self propelled gun fielded by the Italian army, the semovente da 90/53 would be pretty similar to the German waffentragers, basically no armor, poor mobility and a gun as strong as possible for the platform.
Armed with a cannon slightly more powerful than the famous German 88mm L/56, few targets would be able to approach it with impunity as long as its properly camouflaged, while otherwise expecting a quick demise given its glass cannon nature.

Technical data:

Weight: 15,4 tonnes
Armor: 30mm front hull, 8,5mm gun shield, 14mm sides and rear
L:5,2m W:2,3m H: 2,3m
Top speed: 25 km/h

Base gun: Cannone da 90mm L/42
Improved gun: Cannone da 90mm L/53

Base engine:  SPA 8TM40, 125 HP
Improved engine:  SPA 15TM41, 145 HP Diesel

Tier VI: P43 bis

The ultimate P26 evolution, the P43 bis was the very limit of what the italian industrial system could theoretically provide for mass production in 1943.

With a good enough balance of firepower, protection and mobility to rival mid-war heavy tanks it would have been able to go toe to toe with all medium tanks deployed during the war and earlier heavy designs.

Sadly, the gun while more powerful than anything mounted on a tank before, was a cost cutting measure, being a WWI navy surplus design.

Technical data:

Weight: 35 tonnes

Armor: 100mm front, 50mm sides and rear (needs further checks)

L:

Ground Pressure:

Top speed:

Base Engine: SPA 343 420 HP

Improved Engine:  SPA 344 700 HP

Base Gun: Cannone da 75mm L/46

Improved Guns: Cannone da 90mm L/42, Cannone da 105mm L/23

Tier VI:  Semovente 120/44

Unfortunately no pictures are available as the data is made by mostly mentions of a 1943 project, however it's likely the base chassis would be the same or very similar to Semovente 149/40, although the smaller and lighter gun could allow for some casemate and on board ammunition storage.
It is also likely that  the 120/44 is either a typing error or a redesignation of the 120/45 cannon as even Pignato is unsure of its designation.

To further support this, the 120/45 cannon was actually employed on land inside armored trains:

In a configuration similar to German waffentragers the gun could provide very good firepower for its tier although on a relatively slow and very fragile platform.

Base Gun: Cannone da 90mm L/53
Improved Gun: Cannone da 120mm L/45

Hunting Porsches: Typ 245 - 250 - 255

As World War II progressed, resources dwindled and the coming of Speer marked the end of serious support for super-heavy and technically complex designs, Ferdinand Porsche found the need for a radical change of design philosophy.

His advanced petro-electric powered designs were found too demanding in resources and maintenance, with the Porsche Tiger chassis becoming the simplified Elefant and the Maus, his masterpiece, reduced to a production of a few prototypes, constantly tweaked but with no future.

Thus, with a renewed interest in lighter designs, Porsche developed a new concept of tank capable of engaging both air and ground targets using self loading weapons, using as little crew as possible.
The preliminary work for the "Special Vehicle V" family began in May 1943 under own initiative, starting with the Porsche "Typ 245/I", a 18 ton light tank design.

Armed with a 55mm Mk112 belt-fed cannon and a coaxial machine gun, the tank could engage both light vehicles and low flying planes thanks to the turret elevation of 90° and the use of thin walled high explosive shells for maximum fragmentation effect.

The tank was to be powered by a Typ 101 316 HP engine that could reach 345 HP by forced induction and was placed on the rear of the tank giving a top speed of 65 KM/H.

Crewed by 3 people and well protected by a 60mm sloped frontal plate, it was planned to use a smaller version of the truncated cone spring suspension used in the Maus.

An assault gun version of this tank was planned with the Typ 245/2 design, this time armed with a longer 55mm cannon (likely the Mk114) and a machine gun in the turret.
The vehicle was quite low, with an overall height of 1450mm and the crew was reduced to two.
The vehicle was also slightly lighter at 15 tons and this time powered by the smaller transverse mounted Maybach HL116 engine, for a planned top speed of 58 km/h.

In 1944, as the war went on and the need of more effective assault guns ensued, Porsche created a new design family, the 27,1 ton "Special Vehicle VI".
Planning for the use of both hydraulic (Typ 250) and mechanical (Typ 255) transmission, the vehicle was designed for housing larger weapons, a bigger crew and heavier armor.
The primary armament was a semi-automatic 10.5cm howitzer mounted centrally in the casemate with an ammunition load of 50 rounds, while a small turret housed a 30mm MK 108 cannon designed to engage air borne targets again with a maximum turret elevation of 90°.
The driver sat at the left front of the vehicle, the commander in the turret, while  the loader and gunner were on the right.

Early drafts lacked the AA turret and were more akin to Typ 245 in shape and size, while also using a torsion bar suspension rather than truncated cone spring, although all featured cast armor for faster production.

The engine was again mounted transversally on the rear, this time a 18L 500HP V10 engine, propelling the vehicle to a top speed of 57 KM/H.
Frontal armor was angled at 58°, set first at 80 then 120mm thickness, while sides were 45mm thick except for the turret ones, at 80mm.

To maximize protection, the main gun had a large mantlet, although size limitations meant that maximum elevation was 2°, while traverse was 14° on each side and depression -7°.

Several armament upgrades were envisioned, both in the form of a new gun (the 10H64 or a recoilless cannon) and in the form of a belt feeding system to increase the rate of fire.

The Tiger that was never crowned: VK 45.02 (P)

The popularity of World of Tanks is greatly helping to spread interest in tank history, however some of the inaccuracies in the game are starting to create a new strain of internet tank myths.
One of those is about the VK 54.02 (P), Porsche's failed bid for a Tiger successor, represented in WOT by two tanks that are both way above their historical counterpart, especially what they call the "Ausf B".

Today we will use Special Panzer Variants by Spielberger, Panzer Tracts 20-1, Kingtiger Heavy Tank and Germany's Tiger tanks - VK 45-02 to Tiger II by Jentz & Doyle.

The roots of a Porsche Tiger improvement starts in early 1942, with the very first proposal of a "Typ 101 Verstaerkt" (strengthened), soon changed into Typ 180 (Electric transmission) and 181 (Hydraulic), designated by Wa Pruef 6 as VK 45.01 (P2), VK 45.02 (P) and finally Tiger P2.

On 30 January 1942 Dr. Porsche proposed that the Tiger P chassis from N° 101 onwards were to be produced with armor sloped at 60° from vertical, with Krupp reply in early February asking for the sloping to be reduced at 55° to ease manufacture, compatibility with frontal machine gun mounts and a large enough turret ring.


It was to be powered by twin Porsche Typ 101/3 engines, rated at 300 HP each (for a total of 600 HP), with a planned maximum speed of 35 kilometers per hour for the 65 tonnes panzer.
Several upgrade proposals were made in October 1942, installing either twin Porsche Deutz Typ 180/1 generating a total 740 HP, a single Porsche Type 180/2 700 HP engine and even a rear layout configuration:

Armor was set to be 80mm sloped at 55° from vertical frontally, 80mm sloped from 0 to 15° in the sides and 80mm vertical in the rear.

A new turret was designed initially to house the 88mm Flak 41 under Hitler's strict request , which was later on switched to the 88mm KWK 43 used in the Henschel Tiger II, with specifications for it to be to turn at 15 degrees per second under electric power.

Turret frontal armor was 100mm at 45° in the top part, while the bottom one was sloped at 30°, sides were 80mm thick while the rear was also 80mm but sloped at 30°.

Turret roof ranged from 25 to 40mm in thickness.

An initial order was issued for 200 hulls and turrets, later on reduced to 100 turrets and 30 hulls.

Dr. Porsche declared that once the tank hit series production it would have received improved suspensions, an air-cooled 900 HP diesel engine, thicker armor and heavier armament, however the specs of those are not listed anywhere in the sources available to me.
 

Given that the suspension could likely be upgraded to the one used for the Porsche Jagdtiger  I'd personally estimate that an upgraded design would include an extra 50mm plate plus the Krupp 105mm L/52 (or possibly even L/68 for a rear layout) with the later "Henschel" turret (turrets were Krupp in reality) but not much more as the extra 5-6 tonnes doesn't really leave too much room for improvement provided but not exactly assured that Porsche could eventually remove the nasty rocking issues that plagued that particular suspension.

Three Tiger P2 with electric drive were allegedly being completed at Nibelungenwerk before series cancellation in November 1492, while the first 50 turrets were used in the Henschel Tiger II.

"Need more dakka!" - German Flak Panzers

The lack of air superiority became quite a problem for the German army in both World Wars.
Very often you will hear people spouting about "invincible Tigers only defeated by enemy airplanes", which of course was only somewhat true until the Soviets started fielding 122 and 152mm self propelled guns, not to mention the IS series, while British and Americans also put 76mm high velocity cannons to good use on the other side.

The Germans of course were aware of the consequences of loosing air superiority and developed several solutions, of which we will cover only the ones based on tank hulls, ranging from sensible battlefield modifications to daring paper tanks that never reached the battlefield, using mainly "Gepard" by Spielberger and "Panzer Tracts 20-2" by Jentz & Doyle.

2cm Flak 38 auf Panzer I A

Possibly the very first German attempt at a flak panzer,  in 1941 at least 18 by then obsolete Panzer I ausf A chassis were converted into a flak panzer using the ubiquitous 2cm flak 38 and were used with moderate success of the battlefield until Stalingrad, where the last tanks were lost.



2cm Flak 38 auf RSO

A relatively simple modification of the "Ost" tracktor, it was developed as AA/Ground support vehicle for mountain troops. Given similar experiments with the heavier PAK 40 the design seems reliable enough, especially given the dismountable gun specification.
Developed in 1943, it never entered service.

Early modifications based on Panzer 38(t)

Between 1943 and 1944 over 150 of those tanks were produced, putting yet again the 2cm flak 38 in a Marder-like configuration. By then though, their firepower left a lot to be desired but as in late war everything that could be used was fielded, they ended up serving until the very end.

A second attempt was made relatively quickly to make a more flexible configuration, ending up in a recon/AA hybrid armed yet again with the 2cm flak 38 and a MG42, a configuration that would resurface on Paper for the 38D design later on.

Using the sd. kfz 222 turret, 70 of those vehicles were made.

Luftwaffe projects on Luchs/Leopard/VK2801 hulls

 

In September 1943 Krupp and Rheinmetall were requested to submit designs for a light flakpaner carrying the 3.7cm flak 36 (then upgraded to flak 43) or quadruple 20mm flak 38.

The proposal was based on the Luchs but later on maximum integration with Leopard components resulting in a 25 ton tank.

Ground support role was also planned for the tank so the turret had a respectable 50mm front and 30mm sides armor, enough to face most light tanks.

Several configurations were proposed, including the use of a single 5cm Flak 41 or Gerat 58 but ultimately the project was aborted due to the cancellation of the Leopard tank by Speer.

The very same studies were conducted on the VK2801, likely as waffentrager as the same hull configuration was planned to carry the 75mm L/70, although limited to an traverse angle of 15° to each side until the chassis development was aborted in 1945.

Panzer IV based modifications

Being disappointed with earlier attempts, in 1943 Krupp was called in to develop a better solution based on Panzer IV chassis.
The very first solution was to still use the 2cm flak 38 but now in a "Vierling" or quadruple configuration.

This gave a much more intense barrage capability although still relatively short ranged.
Unfortunately the tank was not without drawbacks, resulting in very tall sides when enclosed (earning the nickname of "Mobelwagen" or furniture wagon) and in an unprotected crew when in firing position.

Additional requirements such as entrenching tools and a big supply of hand grenades for close defense (imho this was useless, the main guns could mince meat anything the grenades were meant for at much longer ranges and that close the crew would have been dead meat long before exhausting the grenade supply) meant that insufficient ammo was carried and thus the vehicle never left prototype stage.

A second attempt involved using a newer gun, the 3.7cm Flak 43:

While seemingly puny, the gun was a much stronger advancement from the early 1936 "door knocker" and it could dish out punishment at considerable distances spitting lead up to 250 RPM and also pretty effective against tanks when using special ammunition able to penetrate up to 140mm/0° at 100m.

Both proposals evolved into slightly more compact 22ton turreted designs, called "Ostwind" (east wind, armed with the 3.7cm flak 43), and "Wibelwind" (with the quadruple 20mm) which got over 100 tanks in production.

 

A derivative prototype was made out of Panzer III chassis but it never reached production.

Another design was an enclosed turret with twin MK 103 cannons using a turret derived from U-boat AA, called the Kugelblitz, or ball lighting with about 80 of those being produced:

Of course, being nice designs with reasonable features wasn't enough and like everything else it was brought to the extremes late in the war.

In order to gear up the Wibelwind, the "Zerstorer 45" program was started, bringing a slightly larger turret to mount this:

Quadruple 30mm MK 103 cannon, enough to make minced meat of even the vaunted IL-2 and most light tanks on ground. Only two of those prototypes were made but the hail of fire must have been impressive.

At the same time, Ostwind was planned to be upgraded to "zwilling" or twin, 37mm Flak 43, basically going akimbo:

This was later on planned to be upgraded to the slightly more powerful 3.7cm flak 44.

An heavier configuration was developed in 1942 based on a special Panzer IV chassis mounting the 8.8cm Flak 37 or Flak 41 in a fold-able platform that was later on proposed to be integrated first with Leopard components then with Panther ones but was ultimately discarded for more compact solutions using either 3cm MK 103 or the 5.5cm Gerat 58.

Later modifications based on Panzer 38(t) and 38(d)

As the Panzer IV was scheduled to be phased out, design moved on what was supposed to be its closest replacement, the Panzer 38(d) which could be described as looking like a turreted Hetzer redesigned to be produced in Germany.

Although not evident in the drawing, it sported two 20mm MG 151/20 cannons allegedly for ranging and two MK 103 for the kill, an impressive weapon array for such a compact design.

Later on during flak Panther development the 3.7cm flak 44 was also proposed for the Panzer 38(d).

A final modification was made on an enlarged 38(d) chassis in a waffentrager configuration, using the Gerat 58 in a twin mount.

Panther based modifications

As soon as Panther design started being finalized, flak panzers were being discussed with the very first proposals coming from Luftwaffe in 1942.

Initially a quadruple 20mm MG 151/20 configuration was proposed and trialled but while delivering an impressive barrage, it was deemed insufficient and discarded for twin 3.7cm flak 43.

This configuration, dubbed the "Coelian", was later on upgraded to twin 3.7cm flak 44, which benefited from a longer, more powerful cartridge.

This was again upgraded in 1944 to make use of the new 5.5cm Gerat 58 still in a twin configuration.

Developed by Krupp and Rheinmetall, this impressive weapon could be elevated from -5° to +80°, firing its ammo at over 1000 m/s and 120-140 rounds per minute per gun.

The heaviest modification however regarded using the 8.8cm Flak 41 in an open turret, proposed in 1943 by Rheinmetall and discarded in 1944 as Panther chassis were direly needed for heavier tasts and 8.8cm cannons in fixed positions were felt more than adequate for the tasl.

Modifications by Porsche

Development of a light flak/ground support chassis by Porsche in collaboration with Rheinmetall started in 1943 as resources for heavier designs were drying up, using the 3cm MK 103, 5.5 cm MK 112 and the 10.5cm LEFH 43.

60mm frontal armor and a top speed of 58 KM/H would have made this tank double wonderfully as light scout and support, although that role would have been better covered by its enclosed turret version.

All in all, the germans developed quite a few interesting designs of varying effectiveness, especially as planes got faster and faster.
As with similar designs from other nations, the germans basically focused on sheer rate of fire for closer ranges, while using heavier guns was rapidly becoming the chosen option in later vehicles.

As analogous designs to the soviet ZSU 37 and 57 they could have lasted as anti helicopter/light ground support tanks even after the war, until being ultimately supplanted by a mix of SAM and Radar-equipped SPAAGs.