WesWorld

The early 1940's where an interesting period in Mexican tank history as it saw the appearance of the first Mexican designed and built tanks. The first to appear was the AT-40 MkI Lobo. The first pre-production versions rolled of the line in February 1940. However, due to teething problems the MkI would never enter service.

With the problems with the MkI, the obsolescence of the AT-31Ms, and the projected high cost of the improved MkII, an interim tank was rushed into production, this was the AT-41 Jackal. Basically, an improved AT-31, the AT-41 boasted a new turret with either the 47mm AT gun or the 75mm LV gun. An AA version with twin 25.4mm cannons also entered service.

The AT-40 MkII would finally enter production two years late, in only one version sporting the new American 76.2mm AT gun. This fast and maneuverable tank, was over twice as expensive as the smaller AT-31 and would be built in smaller numbers, serving only with the sole Mexican Armored division.

The AT-18 Mastin, was designed as a complement to the AT-40, based on the American T18, the AT-18 mounted the Mexican turret used on the AT-40 on the American chassis. Costing about the same as the At-40, the AT-18 would serve with the two Mexican Mechanized divisions.



AT-41 MkI Jackal (1941, based on OTL T-46)

crew: 3 (Driver, gunner, commander)
weight: 14 metric tons
armament: 47mm AT or 75mm howitzer or 2x25.4mm AA, 1x machine guns
engine: Continental 9 cylinder radial, 270hp
speed: on-road= 70 Km/h, off-road 34 Km/h
range: 320 Km
armor:
hull front = 30 mm
hull sides = 15 mm
hull rear = 15 mm
hull downside = 15 mm
hull topside = 10 mm
turret front = 30 mm
turret sides = 15 mm
turret rear = 15 mm
turret topside = 10 mm

AT-18 MkI Mastin (1942, based on OTL T18 )

crew: 4 (Driver, gunner, loader, commander)
weight: 25 metric tons
armament: 76.2mm M1A2, 2x machine guns
engine: 2x V-6, 320hp
speed: on-road= 97 Km/h, off-road 30 Km/h
range: 420 Km
armor:
hull front = 50 mm
hull sides = 30 mm
hull rear = 25 mm
hull downside = 25 mm
hull topside = 15 mm
turret front = 50 mm
turret sides = 30 mm
turret rear = 25 mm
turret topside = 15 mm

AT-40 MkII Lobo (1942, based partially on M-18 )

crew: 4 (Driver, gunner, loader, commander)
weight: 20 metric tons
armament: 76.2mm M1A2, 2x machine guns
engine: Continental R-975 9 cylinder radial, 340hp
speed: on-road= 79 Km/h, off-road 40 Km/h
range: 320 Km
armor:
hull front = 50 mm
hull sides = 30 mm
hull rear = 25 mm
hull downside = 25 mm
hull topside = 15 mm
turret front = 50 mm
turret sides = 30 mm
turret rear = 25 mm
turret topside = 15 mm

I'm not quite convinced about the specs of the AT-40 MkII. The Hellcat had a lot less armour than you postulate here, and an open-topped turret besides. I think the balance of speed, armour, and weight is probably optimistic. Perhaps a drop in speed and rise in weight, or a significant decrease in armour, might bring it more in line? Just my humble opinion, of course.

Well compared to the Hellcat it is 2 tons heavier, 18 kph slower, and is smaller in size overall with only 4 crewmen, so will require less armor overall. What are the comparable WW tanks?

Perhaps the most comparable tank, at least in my eyes, would be the M24 Chaffee, which has a 75mm/L40 gun on 18.4 tons - with armour up to 38mm and a speed of 56 kph road / 40kph offroad. Though it does have five crew, which I missed on your design.

On the other hand, there's also the M41 Walker Bulldog, which is 23 tonnes, with a 76.2mm gun, 72 kph, and armour to 38mm. It does have a crew of four. That's a 1951 tank design, though.

I think your design is pretty close to the mark, even so.

Based on experience gained in the Sino-Chosen War, Mexico found a need for a dedicated scout/command/aerial liaison tank. The new tank, was based on the AT-40 MkII and incorporated elements from the Chinese LT-15 which received great reviews. The primary changes where reducing the overall armor to gain speed, maneuverability, and range, and switching out the big 76.2mm gun for a smaller autoloading 47mm based on the one used on the A-10 Javalina. The autoloading allowed the 4th crew member to be a dedicated radio operator. Better radios are included as well as a periscope to allow for scouting from hidden locations.

AT-43 Coyote (1943)


crew: 4 (Driver, gunner, radio operator, commander)
weight: 17 metric tons
armament: 47mm autoloader, 2x machine guns
engine: Continental R-975 9 cylinder radial, 340hp
speed: on-road= 90 Km/h, off-road 49 Km/h
range: 390 Km
armor:
hull front = 40 mm
hull sides = 20 mm
hull rear = 10 mm
hull downside = 20 mm
hull topside = 10 mm
turret front = 40 mm
turret sides = 20 mm
turret rear = 10 mm
turret topside = 10 mm

What is the magazine capacity of the auto-load system?

Well I would assume its similar to the German BK 5cm cannon, so say a 22 round magazine.

Quoted from "Desertfox"

Well I would assume its similar to the German BK 5cm cannon, so say a 22 round magazine.

That would be the Bordkanone 5, the historical weapon?

Assuming Mexico's ability to develop such a weapon indigenously, I see several negative aspects to the use of an autoloader on an armored vehicle.

First, your ammunition outfit is limited to the size of the magazine; since there is no crew member assigned to the task, changing the magazine in combat is a risky option at best.

Your choice of ammunition in a combat situation is limited; you will only be able to use the ammunition type in the magazine of your autoloader; or course, if you are anticipating but a single sort of ammunition, that is not a problem. But if you chose only HE, you will not have the option of switching to AP unless you yank out the entire magazine.

When re-arming, the vehicle will of necessity have to remove itself from the firing line; depending upon the exact nature of tactical employment, this is of greater or lesser importance, and is something all armored vehicles are prone to. But the frequency of such withdrawal will be predicated on the number of rounds in the magazine, and it would seem that the vehicle would quickly expend its 22 round magazine.

JMHO of course.

Yes that cannon.

All are good points, but in this case it is felt that the drawback are outweighed by the benefits. The tank is not a frontline combat vehicle, the gun is mainly for self-defense. Adding a fifth crew member would add weight and require a redesign, while Mexico already had a suitable weapon that was developed for the TNCA A-10 Javalina. This tank should really not be getting into protracted gun fights.

Hmm, I forgot to add smoke grenade launchers.

Quoted from "Desertfox"

All are good points, but in this case it is felt that the drawback are outweighed by the benefits. The tank is not a frontline combat vehicle, the gun is mainly for self-defense. Adding a fifth crew member would add weight and require a redesign, while Mexico already had a suitable weapon that was developed for the TNCA A-10 Javalina. This tank should really not be getting into protracted gun fights.

Hmm, I forgot to add smoke grenade launchers.

If this tank is supposed to operate in the scout role, I think it would be very much in the front line. If it is supposed to be a command vehicle, would it not move forward with the tanks it is expected to command? If it is supposed to serve as a link to supporting aircraft, that is a role that could be more easily by a radio-equipped half track. A specialist vehicle flaunting lots of aerials would make it prime target on the battlefield, and wasteful of effort.

As for the additional weight of the fifth crewman, deletion of the expensive and complex autoloader would easily compensate for his addition; indeed, it might lighten the vehicle.

I used the wrong word, a scout will be on the frontlines, but should avoid combat as it detracts from its primary role of scouting, and a tank that is firing is a tank that is easy to spot. A half-track might be easier, but one of the lessons that will come from combat is that both wheeled and half-track vehicles have a hard time keeping up with fast moving armored columns. So while it is more expensive to have a specialist tank, Mexico feels it is worth it, especially since only a single division will have them and numbers will be limited.

Do you know how much the 5cm KwK 39 L/60 gun weights? I found a value of 1,200lbs for the BK 5, and I assumed it would be light due to its aerial origins.

You do have a point for the command vehicle. I'll use the more heavily armored AT-40 for it since I don't need the extra speed, replacing the 76mm with a 47mm and adding a 5th crewmember.

Quoted

I used the wrong word, a scout will be on the frontlines, but should avoid combat as it detracts from its primary role of scouting, and a tank that is firing is a tank that is easy to spot. A half-track might be easier, but one of the lessons that will come from combat is that both wheeled and half-track vehicles have a hard time keeping up with fast moving armored columns. So while it is more expensive to have a specialist tank, Mexico feels it is worth it, especially since only a single division will have them and numbers will be limited.

Hmm. Modern history has shown that all things considered, wheeled vehicles can cover ground as easily or more easily than tracked vehicles - the Stryker system, the Italian Centauro tank destroyer, the South African Ratel IFV and a host of others - and it is quite unclear whether the limited experience of the Sino-Chosen conflict so far is sufficient to draw such definitive conclusions. Specialist vehicles + Small numbers = Huge Budget; not the best way for a nation with limited industrial potential to proceed.

Quoted

Do you know how much the 5cm KwK 39 L/60 gun weights? I found a value of 1,200lbs for the BK 5, and I assumed it would be light due to its aerial origins.

Strangely enough, I cannot find exact figures for the KwK39 L/60; however, I do know that the deployed weight of the antitank gun was 986 kg, and that included the carriage. The barrel and breech of the comparable British 6pounded weighed in at approximately 350 kg, so I am going to estimate that the 5cm KwK 39 - barrel and breech only - was about the same. That would be less than the stated figure for the BK5.

This is due to the fact that the KwK 39 is the bare-bones weapon, where the BK 5 has to account for a very complicated feed system and magazine (I estimate that a fully loaded magazine would weigh approximately 85 kg - about 43 kg for the rounds themselves and at least an equal amount for hardware). So, the straightforward tank gun is the lighter and less complex weapon.

Mexico hasn't and wont be deploying any of its wheeled fighting vehicles, so the only wheeled vehicles with the Mexican forces are jeeps or heavy duty trucks. And while they might be specialized, they are very similar and use a majority of components from the AT-40, which keeps costs down and helps with logistics over introducing wheeled equivalents.

I'll drop the autoloader then, and add a crewmember for command tanks, and have the commander or radio operator do double duty on the recon tanks. I'll drop the ground-to air liaison for a version of the following:

APC-43 (1943)

An armored personnel carrier based on the hull of the AT-40.
crew: 2 (Driver, Commander/gunner) + 12
weight: 17 metric tons
armament: 25.4mm cannon
engine: Continental R-975 9 cylinder radial, 340hp
speed: on-road= 90 Km/h, off-road 49 Km/h
range: 390 Km
armor:
hull front = 20 mm
hull sides = 20 mm
hull rear = 10 mm
hull downside = 20 mm
hull topside = 10 mm
turret front = 10 mm
turret sides = 10 mm
turret rear = 5 mm
turret topside = 5 mm

Nice drawing.

Question No.1 - where are the engine and the transmission?

Question No.2 - where are the troop doors?

Considering that the men probably exit at the rear, the engine would probably be forward of the turret I think...

On the AT-40 the engine is at the rear like on the Hellcat, but I think it would need to be moved to the front on the APC to allow for doors on the rear.

Doubt the driver would like to have the engine right up his @$$ though.

Quoted from "Desertfox"

On the AT-40 the engine is at the rear like on the Hellcat, but I think it would need to be moved to the front on the APC to allow for doors on the rear.

Precisely; however, that won't work with the engine you have selected. With 1940s technology an engine that size is physically too large to fit forward alongside the driver, and as it is air cooled (IIRC), you risk cooking everybody.

Quoted from "Rooijen10"

Doubt the driver would like to have the engine right up his @$$ though.

You ain't just whistling Dixie!

Armored vehicles are not really my forte, what would be a suitable engine for an APC?