Alternative History Armoured Fighting Vehicles Part 3

[Claymore]

ISOT Hybrid AFV's of the early 1940's Pt. 6

As originally conceived by pattontank12, the major powers of WWII receive designs from the future from a generous and mischievous ASB in 1933, a mid WWII tank, a Cold War era tank and a modern tank.

Germany in this scenario received a Panther ausf. D, a Leopard A1A and a Leopard 2.
Hitler immediately demanded a copy of the Leo-2 but his tank designers and engineers told him they had to walk before they could run with these designs and surprisingly Hitler decided to concede his advisers advice (shocking I know).

The Germans focused on making a hull, chassis and suspension using mostly ideas from the Leo-1 but borrowed a little from the Panther, when the new lower hull design was ready they quickly went about designing a medium tank, a TD, a SPAAG and an SPG so as to get the most from their first futuristic based design.

Top, Pz.II ausf. C armed with 7.5 cm cannon based on the Kw.K 42 L/70 here dubbed the Kw.K 36 L/70.

Second from top, the Jagdpanzer-II armed with the 8.8 cm PaK 36 (PaK 43). A cross between the Leo-I and the Kanonenjagdpanzer.

Third from top, Pz.II Wirbelwind armed with twin 3.7 cm canons.

Bottom, Thor a Nashorn like SPG armed with the PaK 36 (38) L/55 12.8 cm cannon.

All of the these AFV's entered production between 1936 and 1938 so while not as heavily armed or advanced as some of the Allied AFV's, the Panzerwaffe was a decent size and well balanced armoured force with plentiful numbers of spare parts giving them a slight advantage over the British, French and the Soviets but not the US.

I imagine WWII ITTL starting in the spring of 1940.

Will be doing sets of late war era ASB designs in the near but not too near future.

I think the Thor’s gun is OK but its chassis is still very tall - essentially you have a complete Nashorn hull sitting on top of a complete Alt Pz II hull. You might want to blend the two a bit more - say remove everything below the top of the Nashorn’s side grill and the top of the Pz II hull…?

 

[cortz#9]

I think the Thor’s gun is OK but its chassis is still very tall - essentially you have a complete Nashorn hull sitting on top of a complete Alt PZ II Hull. You might want to blend the two a bit more - say remove everything below the top of the Nashorn’s side grill and the top of the Pz II hull…?

Sounds good.

 

[cortz#9]

I think the Thor’s gun is OK but its chassis is still very tall - essentially you have a complete Nashorn hull sitting on top of a complete Alt PZ II Hull. You might want to blend the two a bit more - say remove everything below the top of the Nashorn’s side grill and the top of the Pz II hull…?

How's this?

 

[Claymore]

How's this?
View attachment 826878

My good man, that is beautiful!! 😍😎😍😎😍

 

[vetinari]

Where is the engine?

 

[Claymore]

Where is the engine?

Mid-mounted like the OTL Nashorn, I would guess…

 

[vetinari]

Mid-mounted like the OTL Nashorn, I would guess…

I think it needs another set of roadwheels, to lengthen the hull.

 

[Peebothuhlu]

*Waves*

Hullo, long time no post.

Good to see most every one still about.

So, weird question here.

Just how much bigger would you have to stretch, fold, spindle and mutilate a Jagdpanther hull to fit something like the Abraham 120 gun in there? Would the auto loader 'Save' crew pace or just eat it up?

Heck, could you just cut the top off the Jagdpanther and franken-weld the top of the Abraham turret onto the corpse... uhm, I mean hull?

Reason I ask is the Traveller game am playing. Mucking about with 'Old school tech' married to 'New school' weapon ideas.

Kind of replacing the powder guns with electromagnetic sluggers.

Cheers all.

 

[cortz#9]

Where is the engine?

Mid-mounted like the OTL Nashorn, I would guess…

Yes mid mounted.

 

[wietze]

*Waves*

Hullo, long time no post.

Good to see most every one still about.

So, weird question here.

Just how much bigger would you have to stretch, fold, spindle and mutilate a Jagdpanther hull to fit something like the Abraham 120 gun in there? Would the auto loader 'Save' crew pace or just eat it up?

Heck, could you just cut the top off the Jagdpanther and franken-weld the top of the Abraham turret onto the corpse... uhm, I mean hull?

Reason I ask is the Traveller game am playing. Mucking about with 'Old school tech' married to 'New school' weapon ideas.

Kind of replacing the powder guns with electromagnetic sluggers.

Cheers all.

a jagdpanther is only metre shorter than a leo2, weightwise they are also pretty close.
i'd say the current hull will do
if yr worried about the recoil, can use the low recoil version like the ones used in the centauro 120mm (swiss & italian designs available)

 

[Bougnas]

The current hull will do, the 120mm fits in everything that can fit the 105mm L7, which means everything that can mount the 90mm M41 mostly which is...more compact than the long 88. Ergo the 120mm can fit in place of the 88mm mostly.

 

[Bougnas]

I have recently got some information on the development history of the Leyland L60 and the engines previously intended for Chieftain, both with Bovington's book on the tank and articles from the Leyland society. The summed up version of it is:

- Contrary to what I previously thought, the previous engine intended for Chieftain was not a V8 from Rolls-Royce, but one from Rover in the gasoline form, with Leyland designing a diesel version, both starting from 1955. Rover left the entire military engine market in 1957, leaving only Leyland who found out that the V8 would not deliver the intended 700hp, thus starting a V12 which then turned out too large, leading to its cancellation in early 1958.
Thus: Leyland was the engine designer regardless, all hopes of seeing a more competent player in the field had long vanished. The second thing is that no, the V8 would not have saved Chieftain because it would have been even less powerful than the L60 and badly overloaded. Possibly 2-3 tons could have been saved by keeping the V8, but it would have been badly overloaded and based on the specs of other Western diesels of the day, it could only deliver 550-600hp as a 24L engine at the time.

- The diesel/gasoline engine had been designed after the multifuel requirement was adopted. As such the L60 was not chosen specifically to meet the multifuel requirement, but rather in the hopes that it would be a more power dense engine and could deliver the necessary 700hp in a small package. The choice of an opposed-piston engine was mainly motivated by positive experience from FVRDE on Rootes' TS3 engine the year before. However, TS3 showed that an opposed-piston might perform better than usual as a multifuel. Regardless, conventional diesels could and were made multifuel at the time anyway (AVDS-1790 and MB 837/838), so this solution was not strictly necessary and its more likely that the UK was just getting very excited in a new technology as usual.

- It appears that around 2 years were lost to develop the L60 before Chieftain prototype trials, due to the lengthy negociation process with Rootes who was supposed to assist them. This might have avoided some problems early in prototyping by having a more mature engine and more optimized engine bay, as cooling and airflow were underestimated.

- The multifuel capacity did complicate the engine a bit, but was not really behind its faults. The requirement was relaxed in November 1963 anyway, and in 1966 when looking at a replacement so the engine staying shit so long after that was down to faults by Leyland and inherent design limitations. The Rolls-Royce K60 for example worked well as a multifuel engine and as an opposed-piston engine in general, as did the TS-3, so it is specifically the L60 which was bad.

- In 1958, the Army had demanded that a conventionnal diesel engine alternative be developped by a European country as a backup, but the Treasury refused...only to pay much more to fix the L60 later anyway. That might be the better POD for a fixed Chieftain.

- It is very clear that Leyland's leadership outright lied during development of the L60, as it deemed it oustanding just two weeks after a report from the engineers that there were many faults. It is likely that the L60's development was delayed and slowed down considerably by the inept leadership.

- Interestingly enough, there was a desire to develop a 1000hp version of the L60 Sundance engine from 1978. This would have required adding a turbocharger, which would also have allowed for smaller Rootes blowers and thus lower power losses to scavenging. Such an effort was contemplated in 1963, but at the time the engine was not reliable enough and this setup was deemed too complicated. 760hp was done very unreliably in the 1960-63 period in the normal engine.

The issue of scavenging in the L60 could have been mitigated by having a torque converter in the transmission, as it would multiply torque and reduce the need to operate in the lower gears and low rpms, which make scavenging problematic for 2-stroke engines. With improved scavenging, the addition of a proper turbo could have been more achievable early on.

---

Overall, it is fairly evident that Leyland somehow forgot all its experience working on tank engines in WW2, and the leadership turned to the worse. A rushed development plus the task to develop the whole tank for a couple years did not help.
Having a properly powered Chieftain would most likely require at least the intended Leyland V12 diesel. The engine bay had to be lengthened anyway for the L60 in the end, and a torsion bar suspension could have saved enough weight that overall the tank's weight remained similar or lower than OTL's Chieftain, but with the V12 most likely delivering power in the 800hp range. But this would have affected many other parts and would have required a radically different design, and a different MoD and design team.

 

[vetinari]

Yes mid mounted.

The problem with that, is that the gun is mounted there, so you have serviceability problems, straight away. You simply do not have easy access to the engine. You would need to dismount the gun if you need to replace the engine.

 

[cortz#9]

The problem with that, is that the gun is mounted there, so you have serviceability problems, straight away. You simply do not have easy access to the engine. You would need to dismount the gun if you need to replace the engine.

No you would only need to remove the front of the armoured shield in front of the gun, easier than changing an interleaved roadwheel.

 

[vetinari]

No you would only need to remove the front of the armoured shield in front of the gun, easier than changing an interleaved roadwheel.

I think you have little idea about how big things are. An engine is more than 1-1.5 metres in length, which is bigger than you have allowed for. I am talking about removing an engine, which is at the best of times damned hard. With a bloody big gun over your head it is nigh impossible. You should allow plenty of room for the engine, plus the driver and co-driver. Much easier to make the hull a little longer.

 

[cortz#9]

I think you have little idea about how big things are. An engine is more than 1-1.5 metres in length, which is bigger than you have allowed for. I am talking about removing an engine, which is at the best of times damned hard. With a bloody big gun over your head it is nigh impossible. You should allow plenty of room for the engine, plus the driver and co-driver. Much easier to make the hull a little longer.

Claymore used the same gun on a Nashorn which is smaller than my fictional Pz.II.

For the sake of avoiding an argument I removed the the hull gunner's position to ad some more room.

 

[RedSword12]

ISOT Hybrid AFV's of the early 1940's Pt. 6

As originally conceived by pattontank12, the major powers of WWII receive designs from the future from a generous and mischievous ASB in 1933, a mid WWII tank, a Cold War era tank and a modern tank.

Germany in this scenario received a Panther ausf. D, a Leopard A1A and a Leopard 2.
Hitler immediately demanded a copy of the Leo-2 but his tank designers and engineers told him they had to walk before they could run with these designs and surprisingly Hitler decided to concede his advisers advice (shocking I know).

The Germans focused on making a hull, chassis and suspension using mostly ideas from the Leo-1 but borrowed a little from the Panther, when the new lower hull design was ready they quickly went about designing a medium tank, a TD, a SPAAG and an SPG so as to get the most from their first futuristic based design.

Top, Pz.II ausf. C armed with 7.5 cm cannon based on the Kw.K 42 L/70 here dubbed the Kw.K 36 L/70.

Second from top, the Jagdpanzer-II armed with the 8.8 cm PaK 36 (PaK 43). A cross between the Leo-I and the Kanonenjagdpanzer.

Third from top, Pz.II Wirbelwind armed with twin 3.7 cm canons.

Bottom, Thor a Nashorn like SPG armed with the PaK 36 (38) L/55 12.8 cm cannon.

All of the these AFV's entered production between 1936 and 1938 so while not as heavily armed or advanced as some of the Allied AFV's, the Panzerwaffe was a decent size and well balanced armoured force with plentiful numbers of spare parts giving them a slight advantage over the British, French and the Soviets but not the US.

I imagine WWII ITTL starting in the spring of 1940.

Will be doing sets of late war era ASB designs in the near but not too near future.

Nice. How, on the other hand, might modern ISOT'd military technology be integrated into the early-war tank designs like the Panzer I, II, 38(t), and other things like halftracks? It would be extremely daunting to transition to fully modern designs right away.

 

[cortz#9]

Nice. How, on the other hand, might modern ISOT'd military technology be integrated into the early-war tank designs like the Panzer I, II, 38(t), and other things like halftracks? It would be extremely daunting to transition to fully modern designs right away.

True enough, I cheated on some the allied ISOT tanks by pretending that cold war and modern era armoured cars and APC's were sent back as well, had this been the case, I think more OTL WWII ranks could've benefited.

The designs I posted are the first of a series, I plan on doing some late war tanks that will be a lot closer to cold war ere tanks but now you got me thinking maybe I should go backwards and do maybe a more advanced Pz.IV, Sherman and T-34.
I think the French tanks I did come close to what you're suggesting.

 

[Claymore]

The problem with that, is that the gun is mounted there, so you have serviceability problems, straight away. You simply do not have easy access to the engine. You would need to dismount the gun if you need to replace the engine.

I think you have little idea about how big things are. An engine is more than 1-1.5 metres in length, which is bigger than you have allowed for. I am talking about removing an engine, which is at the best of times damned hard. With a bloody big gun over your head it is nigh impossible. You should allow plenty of room for the engine, plus the driver and co-driver. Much easier to make the hull a little longer.

As @cortz#9 points out, the OTL Nashorn (and Hummel) had its mid-mounted engine situated below the main gun with even less space than the AH Thor and seemed to be acceptable for operational use. I agree that extending the vehicle so that the gun would not interfere with engine access would be better but, clearly, it is not a necessity. Perhaps, the expedience of not having to dramatically change the construction of the hull trumps the consequential complication in engine maintenance… 🤔

 

[Thoresby]

We are talking about Second World War Germany, they have form in building vehicles that are optimised for combat performance at the expense of being complete nightmares to maintain and repair. See Panther and Tiger.