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Mini-competition: fix-a-tank, 1943 Italy edition


Toxn
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1 hour ago, Toxn said:

This is perfect, thanks! With the removal of the mini-turrets I think it won't gain much weight either....

While Im not an expert, but I think there would be some weight gain, thanks to heavily uparmored turret. But the hull on itself, despite thick add on armor would be probably indeed lighter. In any case, thats why I uprated the engine a bit :)

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   Removal of T-28 miniturrets is one of those obvious things in hindsigh, heh. 

   I currently looking at what can be done with BT-5. Looking at schemes of BT-5 and BT-7 it appears that it might be a good idea to get rid of wheel drive, try to put external suspension system (maybe even using original coils) and use additional space for increased turret ring. This should give space for bigger turret and 76.2 mm guns, like BT-7A project with F-32.

 

   With suspension i'm looking at a way to put coils horizontally/close to horizontal, to free space on upper sides of the hull or even move them outside completely using reversed swing arms on rollers to still utilise coils from original vehicle (you can see on roller N3 on pic below). As you see, suspension and wheel drive on BT-5/7 is overcomplicated and space demanding.

1455641442-dvuhbashennyy-bt-3

 

1475898895-3

 

Spoiler

tank-bt-5-5

 

63

 

   Turret ring also can be increased using small turret extension on hull sides. Some hull improvements will make this moded BT-5 closer to T-20/A-20 in terms of looks.

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1 hour ago, LoooSeR said:

   Removal of T-28 miniturrets is one of those obvious things in hindsigh, heh. 

   I currently looking at what can be done with BT-5. Looking at schemes of BT-5 and BT-7 it appears that it might be a good idea to get rid of wheel drive, try to put external suspension system (maybe even using original coils) and use additional space for increased turret ring. This should give space for bigger turret and 76.2 mm guns, like BT-7A project with F-32.

 

   With suspension i'm looking at a way to put coils horizontally/close to horizontal, to free space on upper sides of the hull or even move them outside completely using reversed swing arms on rollers to still utilise coils from original vehicle (you can see on roller N3 on pic below). As you see, suspension and wheel drive on BT-5/7 is overcomplicated and space demanding.

1455641442-dvuhbashennyy-bt-3

 

1475898895-3

 

  Hide contents

tank-bt-5-5

 

63

 

   Turret ring also can be increased using small turret extension on hull sides. Some hull improvements will make this moded BT-5 closer to T-20/A-20 in terms of looks.

This is a good line of thinking.

 

I'd say that radically reworking the suspension might be a bridge too far - but if it were as simple as cutting it out and welding it back onto external brackets then it may be doable.

 

Widening the hull superstructure or adding side bulges (ala T-55 et al) in order to eke out every centimeter of potential turret ring diameter might be the easiest way forward here. I think where you might run into problems is actually with the limited space fore and aft - increase the turret ring size too much and you risk having no space left for the driver or engine.

 

Getting rid of the convertible drive is almost a no-brainer - easy as removing the sprockets and welding the steering linkage to the hull. 

 

The low-energy version, and one that is still perfectly acceptable, would be to eke out the margins on the design by, say: beefing up the suspension coil springs, replacing the road wheels, sprocket and tracks with longer-lasting models (if such can be found), removing the convertible drive, slapping applique armour onto the hull and turret front, replacing the turret rear rack with a local radio and putting a commander's cupola in. This gets you straight into a respectable position by having something that would give 37mm gun crews and Stuart commanders pause.

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2 hours ago, LoooSeR said:

   Removal of T-28 miniturrets is one of those obvious things in hindsigh, heh. 

Thinking about it a bit, I wonder about the pros and cons of just leaving the mini-turrets in but taking out the guns and crew. The result would be fairly useful spaced armour - perfect for eating bazooka rockets and setting off bursting charges. I call this the "funbag airbag" approach ;)

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1 hour ago, Toxn said:

Thinking about it a bit, I wonder about the pros and cons of just leaving the mini-turrets in but taking out the guns and crew. The result would be fairly useful spaced armour - perfect for eating bazooka rockets and setting off bursting charges. I call this the "funbag airbag" approach

I thought about that for a bit... But in the end, I think it doesnt worth keeping them. Removal is a better solution, because you save lots of weight. Then you can bolt on additional armor, add extra ammo, create more space for crew. And as you can see on my drawing, the new armor plates in the place of mini turrets are angled very steeply, so viewed from the front, they provide lots of protection.

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   Behold, power of MS paint and 5 minutes of low effort.

   Reverse swing arm, as much as i don't like them, looks like only way to cram original coils and free up space on upper side armor for storage bins/add on armor that i want to put there. Angling coils is needed to not take whole height of hull, angling them towards rear instead of forward is also dictated by first wheels location regarding frontal upper hull plate.

MSPaint-powa

 

   Looking at turret ring, it appears that rear part of it already touching engine comparment. Not sure how bigger one will work. Now as certain conflict ended, i probably will have more time free for interwebz.

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OK so, road trip is over.
Reading from my (almost illegible) notes I wrote a couple weeks back:

1. Of the available tanks, the BT-5 is, IMO, the only reasonable choice.
1.1. The T-28 cannot be reasonably made a real opponent to the Sherman and is rare, with a spares issue just waiting to happen.
1.2. The various French light tanks and T-26 are disasters on tracks, with no armor, no real option to improve armament, and very poor automotives (low power to weight and low speed suspension).
1.3. Of the guns available, only the 7.62 cm PaK 39(r) can reliably kill a Sherman with AP, and that is neither in service nor will the Germans willingly part with them or their ammo in large quantities; Also, the case is that of the PaK 40, which cannot fit into any of these turrets anyway. Therefore any Sherman killing must require HEAT or some other means of defeating the tank without getting through the armor directly.

2. Why the BT-5 is a good choice
2.1. Most of what made the BT-5 a poor tank IRL are "soft" factors which can be fixed fairly cheaply and quickly, if the goal isn't to go up against Shermans.
2.2. The BT-5 is uniquely suited to being weighted down, owing to the frankly ludicrously over-specced drivetrain.
2.3. The added weight of the BT-7 vs the -5 did not by any source I've found adversely affect reliability, and again as far as I can tell the suspension was not heavily modified.
2.4. For going up against light tanks, the 45mm is quite good and perhaps does not require replacement at all, for a low-end option.
2.5. The sheer number taken intact by the Germans, as well as the large number of spares salvageable from disabled ones, allows a large and capable fleet.

3. Proposed BT-5 upgrade:
3.1. Mobility
This is in fact a bit of a downgrade, to cope with the increased weight to be mentioned later.
3.1.1. Increasing the preload of the springs by spacers in the spring wells, to retain ground clearance.
3.1.2. Installing volute bump stops on first and last road wheel stations to prevent over-stressing springs, at cost of some of the very generous travel.
3.1.3. Installing drive wheels with 5 rather than 6 drive nubs to raise final drive ratio  - prevents over-stressing drivetrain at the cost of reduced speed at all gears. Even at a 5:6 reduced speed, the BT-5 is silly fast.
All in all, very easy to do, requires light welding work to install bump stops and requires fabricating new drive wheels - not hard at all. Should allow a weight of around 15T vs the original 12T or so. Ground pressure in Italian terrain is also not that big of an issue, and the BT-5 has silly low MMP ground pressure anyway thanks to the massive track pitch.



... and just like that, my posting time for the day has run out.
What will N-L-M do with 3 tons of extra weight on a BT-5?
Tune in next time for another exciting episode of...
pimp my tank!

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9 hours ago, N-L-M said:

OK so, road trip is over.
Reading from my (almost illegible) notes I wrote a couple weeks back:

1. Of the available tanks, the BT-5 is, IMO, the only reasonable choice.
1.1. The T-28 cannot be reasonably made a real opponent to the Sherman and is rare, with a spares issue just waiting to happen.
1.2. The various French light tanks and T-26 are disasters on tracks, with no armor, no real option to improve armament, and very poor automotives (low power to weight and low speed suspension).
1.3. Of the guns available, only the 7.62 cm PaK 39(r) can reliably kill a Sherman with AP, and that is neither in service nor will the Germans willingly part with them or their ammo in large quantities; Also, the case is that of the PaK 40, which cannot fit into any of these turrets anyway. Therefore any Sherman killing must require HEAT or some other means of defeating the tank without getting through the armor directly.

2. Why the BT-5 is a good choice
2.1. Most of what made the BT-5 a poor tank IRL are "soft" factors which can be fixed fairly cheaply and quickly, if the goal isn't to go up against Shermans.
2.2. The BT-5 is uniquely suited to being weighted down, owing to the frankly ludicrously over-specced drivetrain.
2.3. The added weight of the BT-7 vs the -5 did not by any source I've found adversely affect reliability, and again as far as I can tell the suspension was not heavily modified.
2.4. For going up against light tanks, the 45mm is quite good and perhaps does not require replacement at all, for a low-end option.
2.5. The sheer number taken intact by the Germans, as well as the large number of spares salvageable from disabled ones, allows a large and capable fleet.

3. Proposed BT-5 upgrade:
3.1. Mobility
This is in fact a bit of a downgrade, to cope with the increased weight to be mentioned later.
3.1.1. Increasing the preload of the springs by spacers in the spring wells, to retain ground clearance.
3.1.2. Installing volute bump stops on first and last road wheel stations to prevent over-stressing springs, at cost of some of the very generous travel.
3.1.3. Installing drive wheels with 5 rather than 6 drive nubs to raise final drive ratio  - prevents over-stressing drivetrain at the cost of reduced speed at all gears. Even at a 5:6 reduced speed, the BT-5 is silly fast.
All in all, very easy to do, requires light welding work to install bump stops and requires fabricating new drive wheels - not hard at all. Should allow a weight of around 15T vs the original 12T or so. Ground pressure in Italian terrain is also not that big of an issue, and the BT-5 has silly low MMP ground pressure anyway thanks to the massive track pitch.



... and just like that, my posting time for the day has run out.
What will N-L-M do with 3 tons of extra weight on a BT-5?
Tune in next time for another exciting episode of...
pimp my tank!

 

I'd say that, of the French tanks, the S35 is about the best bet to create a useful vehicle, and could probably support a much larger turret ring than it had historically (perhaps as large as 1.5m!). The PzII also has some hidden potential, although it's a lot more tightly packed and might support a turret ring of maybe 1.2m. That's in the same range as the BT-5 (which doesn't have much growth potential in that department at all), and gives you the opportunity to propose your own turret layout.

 

Another dark horse in all of this, to my mind at least, is the Puppchen. It may not have the best effective range, but for that you get something with next to no recoil and the ability to smash any armour you're likely to face. This is where a layout similar to the modern BMP-3 (a high-velocity small-calibre gun mounted alongside a lower-velocity large-calibre gun) might be used to provide an all-around useful armament.

 

 

 

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I think that I will not give any drawings or 3D (any free 3D models for BT or Somua out there in the internet?) but I think I can share my thinking. Maybe it can inspire someone or at least add something into discussion. 

 

Somua S-35. 

IMHO the tank is not that bad platform. As it is bolted from three parts I suggest to replace the entire front-upper hull section with a new one. I don't think that replacing engine, gearbox or suspension is worth the effort (I guess creating an all new vehicle would make more sense). Moreover it's quite ok on the original vehicle. 

The new front-upper hull section would be welded with sloped single front plate  in a way to enlarge turret ring as possible (the sloped UFP with the same bottom and top edge as the original allows to move the driver a bit to the front and move also the turret axis slightly to the front and thus enlarge its ring a little bit). One particular issue, I see here, is that to replace the engine it was necessary to unbolt the entire rear-upper hull section and remove it with a crane. In our case with larger turret it would mean that the turret also needs to be removed before the engine is replaced (I don't know how it was with the original). Therefore the turret needs also hooks for the crane. 

The turret shall be new welded one for two men instead of one (I don't think we can fit three there together with a bigger gun) and with commander's cupola. As for the gun I think we could fit the Italian 75/34 gun for which they had ammo and which was basically the best what the Italians had. I'm quite confident that this gun could fit in the turret. Another option could be the Škoda A11 47/L43,4 which was able to penetrate 100 mm at short distance but only with APCR PzGr. 40 about which I don't know if it was available for Italy. Otherwise this very compact gun would allow to opt for not too big turret and reduce the extra weight increase. Of course the HE would be much worse. 

Another improvement would be to add armoured glass vision blocks for all crew members instead of the vision slits, including for the cupola and a periscope for the gunner.

The radio operator would get a machine gun because in my opinion in WW2 it was good to have the bow MG and also to use the radio operator more (now he's not needed as half-loader as with the single men turret anymore). 

The radio would be replaced with Italian RF-1CA.  

Both machnieguns would be Breda mod.38 for the sake of unification not for their performance. 

The big question is armor protection. The bigger turret and gun, the bow MG and its ammo and the fourth crew member would definitely add weight. The standard Somua was very well protected when created but by 1943 it's not enough. I think it would make sense to remove the armoured pannels from the suspension and thus save a lot of weight which can be used for the new turret etc. The suspension would maybe need stronger leaf springs but that is probably doable. I'm not able to say how inbalanced the original tank was and how much worse it would therefore be after the redesign. All in all I don't think that it's safe to think about more than 50-60 mm steel plates used for UFP and turret front. The exposed and very large original LFP could get at least 10 mm flat spaced armor bolted on welded spacers. Anyway since both UFP and the spaced armour for LFP would be very easy to replace, we could put maximum what the suspension could cope with based on the testing. 

 

BT-5

I was thinking to offer to the army something not exactly asked for. The BT-5 thanks to it's ridiculous engine and speed and small size and weight could be used as an ideal platform for an armoured scout vehicle with great off-road capability.

 It needs new turret in which I would sacrifice the gun for having two radio sets placed directly in the turret for the commander. The turret could be either opened (probably better for scout car) or closed with a large commander's cupola (more expensive and heavier).

As an armament I would go for the belt-fed ZB-60 15 mm autocannon (BESA 15 basically) with large elevation angle to allow its effective use also in the mountains and possibly against aircraft. The gun could penetrate 28 mm from short distance which is not enough against tanks but could be probably enough to spray anything it encounters and run away. An alternative (larger but more standard for Italians could be Breda 20/65 autocannon but its feeding isn't ideal for being placed inside a turret. Personally I would go for the smaller ZB-60 here. 

I would replace also the UFP with one with larger and differently shaped driver's cabin with better visibility (three vision blocks with armoured glass giving better viewing angle for more efficient use of the vehicle speed). Since this vehicle would not serve as a tank I think better visibility is much more importnant than armor protection.

For the scout job I would adjust the UFP and the turret front thickness to be resistant to M2 Browning only. Well sloped 25 mm on the UFP and slightly sloped 30 mm on the turret shall be enough. Since I would remove the gun and a lot of ammo and the turret roof I don't think there would be any weight increase even with such armor adjustment.  

IMHO this conversion would be also very cheap. 

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My submission: "P 28/32

 

OwiSGRc.png

 

Spoiler

YLeaJma.png

LHdlrJH.png

h2gISvy.png

 

I used the T-28 hull and modified it by reworking the entire front and widening the turret ring to the side of the hull (it is now ~1.85m wide). The gun is an leFH 16 or leFH 18/1, German stock that is probably phased out of service by 1942-43 (the 16 was definitely not in front line service).  Also, by this time, HEAT shells were starting to be added to inventory, which gives the tank the ability to engage the Sherman from the front, and from any range. As you guess by the name, the P means this tank is meant to support the M13s, 14s, and 15s in service by engaging targets the smaller M series would have difficulty with (bunkers, and the M4 Shermans). The 28 is an homage to the tank it's based on (T-28), and the 32 is based on the expected weight. 

 

Still working out details, but the vehicle is suppose to be about 32 tons, with a 30mm glacis plate (50mm drivers visor), 45mm turret front, mantle, and copula, 30mm turret sides and rear. Other armor is the same as the T-28. There are 5 crew: Commander and gunner in the right of the turret (gunner forward, commander behind), 2 loaders (both left side of the turret), and the driver (front and center of the hull). The rear of the turret houses the radio (behind the commander), the machine gun magazines (1-2 8mm Breda mod. 38, stored next to the radio), and the 105mm shells (taking up half of the back of the turret). The propellant and rest of the shells are stored on either side of the driver, and in a "ready rack" in the center of the turret, beneath the gun breach (2 or 3 full propellant charges). Engine, suspension, and transmission are all the same as the T-28. 

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10 hours ago, Lord_James said:

My submission: "P 28/32

 

OwiSGRc.png

 

  Reveal hidden contents

YLeaJma.png

LHdlrJH.png

h2gISvy.png

 

I used the T-28 hull and modified it by reworking the entire front and widening the turret ring to the side of the hull (it is now ~1.85m wide). The gun is an leFH 16 or leFH 18/1, German stock that is probably phased out of service by 1942-43 (the 16 was definitely not in front line service).  Also, by this time, HEAT shells were starting to be added to inventory, which gives the tank the ability to engage the Sherman from the front, and from any range. As you guess by the name, the P means this tank is meant to support the M13s, 14s, and 15s in service by engaging targets the smaller M series would have difficulty with (bunkers, and the M4 Shermans). The 28 is an homage to the tank it's based on (T-28), and the 32 is based on the expected weight. 

 

Still working out details, but the vehicle is suppose to be about 32 tons, with a 30mm glacis plate (50mm drivers visor), 45mm turret front, mantle, and copula, 30mm turret sides and rear. Other armor is the same as the T-28. There are 5 crew: Commander and gunner in the right of the turret (gunner forward, commander behind), 2 loaders (both left side of the turret), and the driver (front and center of the hull). The rear of the turret houses the radio (behind the commander), the machine gun magazines (1-2 8mm Breda mod. 38, stored next to the radio), and the 105mm shells (taking up half of the back of the turret). The propellant and rest of the shells are stored on either side of the driver, and in a "ready rack" in the center of the turret, beneath the gun breach (2 or 3 full propellant charges). Engine, suspension, and transmission are all the same as the T-28. 

Looking good, although I have to ask why you settled on the short 75 after going to all the trouble to make a turret ring which could mount a 100mm gun ;)

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This might be of interest to @Lord_James and @heretic88: removing the miniturrets saves about 300kg each (not counting crew) by my calculations. At the same time, simply extending the superstructure and relocating the cabin while retaining the same armour thickness (as Lord-James did) nets you just under 600kg of mass. So for him the weight difference is a wash.

 

For Heretic the situation seems a little more complex. From the model I have available, it looks like he changed the angle of the cabin (from around 20' to 30' from the vertical), changed the angle of the upper front glacis and put in triangular side plates that go from the turret platform to the side of the cabin. That and the extra armour means that I'm not sure what the weight difference would be over the original.

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Placed my updated, finalized submission in the other thread. Quite pleased with it, even if it's 1 ton heavier than planned (name updated to reflect the new weight). 

 

@Toxn, it can actually mount the Italian 120mm howitzers (120/21, 120/25, and 120/27) on this thing, there's enough room. However, none of those guns received HEAT, or even AP for that matter (that I can find), and the Italians don't appear to have produced HEAT shells for their 75-105mm guns until 1944 (probably due to German assistance). The leFH 16 is the best compromise of availability and firepower that I can come up with. 

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On 10/12/2020 at 4:43 PM, Toxn said:

Licenced production yes, sale no.

 

Production licences are also available for all ammunition currently in German use (ie: non-experimental), although no strategic materials (copper, tungsten) or products will be sold to Italy.

 

4 hours ago, Lord_James said:

Placed my updated, finalized submission in the other thread. Quite pleased with it, even if it's 1 ton heavier than planned (name updated to reflect the new weight). 

 

@Toxn, it can actually mount the Italian 120mm howitzers (120/21, 120/25, and 120/27) on this thing, there's enough room. However, none of those guns received HEAT, or even AP for that matter (that I can find), and the Italians don't appear to have produced HEAT shells for their 75-105mm guns until 1944 (probably due to German assistance). The leFH 16 is the best compromise of availability and firepower that I can come up with. 

There's your solution ;)

 

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