WesWorld

As for the V44 issue.... how do these modified figures look?

Upper Glacis: 25@45 ----> 20@30
Lower Glacis: 25@45 ----> 25
Turret Armor: 25@30 ----> 20@30
Road Speed: 92 ---> 60 kph
Offroad Speed: 60 ----> 40 kph
Ground Pressure: 9.53 ----> 12.83 PSI
Main Gun: 20mm L/85 ----> 20mm L/50


V44, Infantry Fighting Vehicle
Crew: 3 (Driver, Gunner, Commander)
Passengers: 11
Weight: 21 metric tonnes

Length: 5.6 m w/o gun
Width: 2.69 m over tracks
Height: 2.30m over cupola

Primary Armament: 1 x 20mm L/50 Autocannon (450 rounds), 1 x 100mm L/17.7 Mortar - Breachloading (60 rounds)
Secondary Armament: 1 x 7.62mm MG (Bow - 3125 rounds)

Hull Armor Upper: 20mm@45 / 25mm / 25mm
Hull Armor Lower: 25mm / 25mm / 25mm
Turret Armor: 20mm@30 / 20mm@30 / 20mm@30
Engine: 330hp 4-cycl Diesel
PWR: 15.7 hp/tonne
Suspension: Double Torsion Bars
Track Type: Dead
Wheels per side: 8
Track Width: 300mm
Ground Pressure: 88.4 kPa (12.83 PSI)

Range: 320km (road), 200km (offroad)
Speed: 60kph (road), 40kph (offroad)

I am concerned here that the doctrine espoused here, appropriate to the situation or not, is being used to justify the introduction of equipment that is quite far in advance of the state of the art for the period. Even down-rated, the M44 IFV is inappropriate for a mid-1944 introduction; the tactical experience that would call such into being does not exist in any of the armies of Wesworld Europe.

Well I suppose I'll take another route then, of limited deterrence and delay.

Said goal would be to have a minimally sized force capable of preventing the annexation of Denmark prior to the passage of a week. Afterward, the army is to be capable to sustaining a government-in-exile.

Some preliminary figures/ideas:
- Removal of one of the mainstay divisions, reducing force strength from 35,955 men to 22,655 men.
- Heavy reduction in level of mechanization of force, accompanied widespread fortifications.
- City Rings around coastal cities, from which troops will be extracted to the navy.

Your lack of confidence in the Danish - German Treaty of Mutual Friendship and Non-Aggression is disappointing.

I don't think expanding fortifications and reducing mechanization is a smart move. The Belgian ostriches aside, most everyone in Europe is downsizing and moving toward more capable, more mobile troops. To turn Denmark into another Bunker Nation would be... kinda disappointing, really.

Funding an army for millions of Krone that can only withstand an invasion for a week is economically pointless. The cost-effectiveness is just not there. While Germany is the only plausible invading nation, such chances are more than slim and realistically a Germany with paratroop forces, 7,000 military aircraft and amphibious assault ships, any defending line is useless.

(Belgium counters such claims by saying it has both flanks protected by Dutch and French lines and any German seaborne assault has to pass through seas defended by the Dutch and Royal Navy)

Quoted from "Hood"

(Belgium counters such claims by saying it has both flanks protected by Dutch and French lines and any German seaborne assault has to pass through seas defended by the Dutch and Royal Navy)

And the Belgians have protected their Channel coast against an invasion by the Royal Navy, just in case.

Nah, just to prevent those pesky German sunbed hogs putting their beach towels everywhere!

Air-transportable Light Tank for the Danish army.

The M45 Light Tank has very little in the way of armor, only sufficient against small-arms front, although the front is rated to protect against 12.7mm MG fire.

Several measures have been taken to expedite field and shop repairs: The engine and transmission are is mounted separately on rollers with an easy access door in the rear. The two rear deck grills are connected to the access door on the opening edge and are mounted on hinges, the hinges themselves secured with simple locking bolts.

Instead of a Torsion Bar suspension, an external system is used instead - the HVSS. If a bogie broke or was destroyed, replacing and repairing would be a simple matter - unlike the ordeal of repairing a snapped torsion bar.

The airborne requirement limited the tank weight to a maximum of 8.16 metric tons (18,000 lb) and as such the armor is inadequate for protracted engagements. However, the M45 is designed with bolts on the glacis and turret front for the attachment of applique armor. The transmission and suspension are rated for a 11 metric ton vehicle, which allows for the addition of applique armor thick enough to protect vs 75mm fire from the front and 12.7mm fire from the sides. Whilst such an up-armored vehicle would be unable to be carried into battle by parachute by tactical aircraft or glider, it removes the need for a separate vehicle for general army use.

Quoted

L45E1-AB
Crew: 4 (Driver, Gunner, Loader, Commander)
Weight: 7.96 metric tonnes

Length: 4.4 m w/o gun
Width: 2.26 m over tracks
Height: 2.20m over cupola

Primary Armament: 1 x 75mm L/43 (24 rounds - 8 ready)
Secondary Armament: 1 x 7.62mm MG (Bow - 4000 rounds), 1 x 7.62mm MG (Pintle - 4000 rounds)

Hull Armor Upper: 9.53mm@60 / 9.53mm / 9.53mm@13
Hull Armor Lower: 9mm@50 / 9.53mm / 8mm@35
Turret Armor: 9.53mm@22.5 / 9.53mm@22.5 / 9.53mm@22.5, 25mm Mantle
Engine: 110 kw V-2 Diesel (150hp) on Rollers
PWR: 18.84 hp/tonne
Suspension: HVSS
Track Type: Live
Wheels per side: 5 x 50mm Rubber-Tired Wheels - 2 Bogies with 1 Track Tension Idler (Drive Sprocket not counted)
Track Width: 254mm (10") Continuous Band with Rubber Pads
Ground Pressure: 63.86 kPa (9.3 PSI)
Ground Clearance: 0.5m

Range: 180km (road), 120km (offroad)
Speed: 46kph (road), 26kph (offroad)

The up-armored general-use army variant:

Quoted

L45E2-GM
Crew: 4 (Driver, Gunner, Loader, Commander)
Weight: 11 metric tonnes

Length: 4.4 m w/o gun
Width: 2.26 m over tracks
Height: 2.20m over cupola

Primary Armament: 1 x 75mm L/43 (24 rounds - 8 ready)
Secondary Armament: 1 x 7.62mm MG (Bow - 4000 rounds), 1 x 7.62mm MG (Pintle - 4000 rounds)

Hull Armor Upper: 52.53mm@60 / 22.53mm / 17.53mm@13
Hull Armor Lower: 47mm@50 / 22.53mm / 16mm@35
Turret Armor: 69.53mm@22.5 / 17.53mm@22.5 / 17.53mm@22.5, 25mm Mantle
Engine: 110 kw V-2 Diesel (150hp) on Rollers
PWR: 13.63 hp/tonne
Suspension: HVSS
Track Type: Live
Wheels per side: 5 x 50mm Rubber-Tired Wheels - 2 Bogies with 1 Track Tension Idler (Drive Sprocket not counted)
Track Width: 254mm (10") Continuous Band with Rubber Pads
Ground Pressure: 88.19 kPa (12.8 PSI)
Ground Clearance: 0.5m

Range: 120km (road), 80km (offroad)
Speed: 34kph (road), 20kph (offroad)

I have several concerns with the design, some of which pertain to the airborne variant, and others to the general purpose variant. In dimension and weight the proposed M45 is broadly similar to the historical M22 Locust; so I will make my comparisons with that vehicle.

The first has to do with internal volume – the M22 was but a three-man vehicle, with a smaller gun (and thus a smaller volume taken up by ammunition storage); the proposed M45 requires a crew of four – three of whom occupy the turret – and its 24 rounds of 75mm ammunition would occupy a far larger volume than the fifty 37mm rounds of the M22. I have grave misgivings about the ability to shoehorn everything into a hull limited by the dimensions of the proposed M45.

The second has to do with armament – I question whether the maximum possible turret ring for the M45 has sufficient size to accommodate the recoil stroke of a 75mm gun; at L/43 it is at least a mid-velocity weapon. With three men in the turret the loader’s job would be rather deadly – I fear that in combat conditions the loader would be struck by the recoiling gun; some of the postwar Soviet designs were notorious for this fault. Manhandling 75mm rounds in a turret that could be mounted on such a small vehicle would also have its problems, leading to a low rate of fire for the main armament.

For the airborne variant, I find the armor protection derisory; though this is acknowledged and perhaps acceptable for an airborne tank – if one really needs an air-transportable vehicle. I have more concern with the concept of the applique armor for the general purpose variant – a lot of armor is being added over a large surface area of the vehicle. I suppose it could be done but I would be concerned at running into interference fits; the engineering would have to be precise and the installation perfect.

On doctrinal points, why would Denmark need an air-transportable tank? Yes, Denmark has colonial possessions to which such vehicles might have to be airlifted, but is that a sufficient requirement for the development of such a specialized vehicle? It then begs the question of what aircraft will carry this vehicle. The combination will be expensive any way you slice it.

Quoted from "Logi"

Instead of a Torsion Bar suspension, an external system is used instead - the HVSS. If a bogie broke or was destroyed, replacing and repairing would be a simple matter - unlike the ordeal of repairing a snapped torsion bar.

That's an odd choice. HVSS isn't bad, but torsion bar generally takes up a lot less weight and space, and I've never heard it being all that difficult to maintain. (I'd have said HVSS was the more maintenance intensive of the two systems, actually.) If weight is such a crucial thing on this tank, moving away from a torsion bar system seems to be a poor choice.

I agree with Bruce about placing such a large gun on such a small hull. I could maybe see a tank destroyer with a non-turreted mounting, or maybe, at the outside, the oscillating FL-11 turret with the low-velocity 75mm gun, as used on the Panhard EBR armoured car. That has its own potential problems, though.

Quoted from "Brockpaine"

Quoted from "Logi"

Instead of a Torsion Bar suspension, an external system is used instead - the HVSS. If a bogie broke or was destroyed, replacing and repairing would be a simple matter - unlike the ordeal of repairing a snapped torsion bar.

That's an odd choice. HVSS isn't bad, but torsion bar generally takes up a lot less weight and space, and I've never heard it being all that difficult to maintain. (I'd have said HVSS was the more maintenance intensive of the two systems, actually.) If weight is such a crucial thing on this tank, moving away from a torsion bar system seems to be a poor choice.

A Panther or Tiger-style torsion bar suspension with interleaved road wheels would make for much extra weight, complex manufacturing and would be a maintenance nightmare, though I do not think that style of suspension is envisioned in this case. Still, I can see the rationale for it. I've found a drawing of a typical tank torsion bar suspension here.

As you can see, the torsion bars run across the floor of the fighting compartment, which, given the constraints of volume in this particular instance, is a concern. Every square centimeter of volume is going to matter in this vehicle, and the space needed to clear the torsion bars reduces that by a significant margin. The bulk of the ammunition storage is going to be on the floor of the vehicle (no way all the ammunition could be stowed in the turret) and that, with four crewmen, engine, fuel, transmission etc, will rapidly fill a the vehicle.

The HVSS suspension (which was on the historical M22 Locust) does not take up interior space. If a track is blown off by a mine, it is far easier to replace a bogie unit than attempt to remove a snapped torsion bar, which would necessitate removing road wheels on both sides of the vehicle and then extracting it. As a small vehicle would be particularly vulnerable to any sort of antitank mine, this is a consideration.

I'll briefly go over the suspension choice for now:

In the case of a snapped torsion bar you have to remove the wheel and then the external lever. If there are other things in the way (wheels for interleaving, skirts, etc.) you will have to remove them first as well. Then you have to remove what is left of the torsion bar, then remove the other end of the torsion bar. If their are fragments, you have to extract each and every one of the fragments before putting in a new torsion bar. This is somewhat easier if the torsion bar is unguided, since you have better vantage points to pick up the pieces. As a snapped torsion bar will likely have a lot of fragments, you can see this is not a repair you can do in the field. Even in the depot it is a bit of a headache.

In contrast, a external bogie suspension is pretty simple - take off the bogie and place a new one on. If you have one lying around for some reason or a depot tank has on available, you can repair the suspension in the field and off you go.

The reason torsion bars are better than external bogies is:
- It is a smoother and more comfortable cross-country ride at slow speeds.
- It has less tractive resistance.
- It's less likely to be damaged by side-hits.
- It is far easier to produce in factories!

As Bruce points out: a torsion bar system actually takes up more space than a HVSS system, mainly because a torsion bar system is still internal where the HVSS is external.

Space and weight is critical, and torsion bar systems take up both! (By increasing the height, they increase the area of the armored plate, etc. etc.)

Quoted

In dimension and weight the proposed M45 is broadly similar to the historical M22 Locust; so I will make my comparisons with that vehicle.

It is only similar in weight.... if you look at the dimensions, they do not match.

The L45E1-AB stats vs M22 Locust:
Weight: 7.96 mT vs 7.44 mT
Length w/o Gun: 4.4 m vs 3.94 m
Width without Tracks: 1.9 m vs 1.68 m
Height w/o Ground Clearance: 1.7m vs 1.59 m
Average Hull Armor: 9.53mm Sloped vs 13mm Sloped
Average Turret Armor: 9.53mm Sloped vs 25mm Sloped
Turret Ring: 1.75 m (69") vs 1.2 m (47.45")

The L45E1-AB is bigger but with much thinner armor than the M22 Locust. In fact, assuming the dimensions form a box, the L45E1 occupies a volume of 14.212 m3 and the M22 Locust occupies 10.953 m3, meaning the L45E1-AB has at minimum 30% more volume than the M22 Locust. Minimum because it skews the calculation to make the M22 Locust occupy more space than it really does due to it's smaller turret ring.

In fact the L45E1-AB volume is closer to the M5 Stuart:
Weight: 7.96 mT vs 15 mT
Length w/o Gun: 4.4 m vs 4.3 m
Width without Tracks: 1.9 m vs 1.65 m
Height w/o Ground Clearance: 1.7m vs 2.171 m
Average Hull Armor: 9.53mm Sloped vs 25mm Sloped
Average Turret Armor: 9.53mm Sloped vs 38mm Sloped
Turret Ring: 1.75 m (69") vs 1.19 m (46.75")

By comparison the L45E1-AB has smaller engine volume and fuel capacity since it achieves a slower road speed and similar range on half the weight. It has much less ammunition volume (about ~0.13 m3 vs ~0.18 m3) compared to the M5 Stuart with a much larger turret ring and hence turret volume. This leads me to think that it won't be particularly cramped in the turret. I'm not sure how many rounds are stored in the turret - but almost all the rounds in the L45E1-AB are under the turret basket or in the hull - the ready rounds are the only easily accessible rounds. Rate of sustained fire will suffer from this, but that is acceptable due to the risk of cooking out from an ammunition hit, especially since the armor is so thin.

Quoted

On doctrinal points, why would Denmark need an air-transportable tank? Yes, Denmark has colonial possessions to which such vehicles might have to be airlifted, but is that a sufficient requirement for the development of such a specialized vehicle?

It is for power projection, not the protection of colonial assets. The reason lies in diplomacy - I will go over that in another time.

Quoted

It then begs the question of what aircraft will carry this vehicle. The combination will be expensive any way you slice it.

I find the question as bit strange - you clearly mentioned the M22 Locust in your comparison, then talk of what aircraft will carry the vehicle - as if it is somehow much heavier, etc. such that what could carry the M22 could not carry a L45E1-AB.

It is as a M22 Locust - Hamilcar, C-46s, C-47s (on emergency loads), C-54s, and C-119s (when they are produced). I don't think it is a particularly unique ordeal to carry a 8 mT tank, unlike say a 18.4 mT tank (like a M24 Chaffee).

Quoted

It is only similar in weight.... if you look at the dimensions, they do not match.

As for the comparison of the M22 with the proposed M45, I said broadly similar – not an exact match. The two are airborne tanks, of comparable mass, of close dimension.

But since you have now provided a dimension for the M45’s turret ring, I have to ask -

The width of the M45, without tracks is 1.9 m - the turret ring of the M45 is 1.75 m; that leaves 75mm of clearance on either side of the turret ring. How wide is the turret at its base?

Quoted

It has much less ammunition volume (about ~0.13 m3 vs ~0.18 m3)

I would find your calculations behind this assertion enlightening, inasmuch as the M5’s 37mm round masses less than a third of a mid-range 7.5cm round, such as the PzGr 39.

Quoted

I find the question as bit strange - you clearly mentioned the M22 Locust in your comparison, then talk of what aircraft will carry the vehicle - as if it is somehow much heavier, etc. such that what could carry the M22 could not carry a L45E1-AB

It is as a M22 Locust - Hamilcar, C-46s, C-47s (on emergency loads), C-54s, and C-119s (when they are produced). I don't think it is a particularly unique ordeal to carry a 8 mT tank, unlike say a 18.4 mT tank (like a M24 Chaffee).

But as far as I know, Denmark has no aircraft capable of carrying such a vehicle, whether powered or glider. Are you giving us forewarning of Denmark’s future aviation developments or should we send sales catalogs to Copenhagen?

Quoted

I would find your calculations behind this assertion enlightening, inasmuch as the M5’s 37mm round masses less than a third of a mid-range 7.5cm round, such as the PzGr 39.

You are overthinking things. I simply stated the approximate total volume. The L45E1 carries 24 75mm rounds. The M5 Stuart carries 144 37mm rounds. 144x37mm takes more space than 24x75mm. Is there something controversial about this statement?


As for the airplane issue, send the catalogs.

Quoted from "Logi"

Quoted

I would find your calculations behind this assertion enlightening, inasmuch as the M5’s 37mm round masses less than a third of a mid-range 7.5cm round, such as the PzGr 39.

You are overthinking things. I simply stated the approximate total volume. The L45E1 carries 24 75mm rounds. The M5 Stuart carries 144 37mm rounds. 144x37mm takes more space than 24x75mm. Is there something controversial about this statement?


As for the airplane issue, send the catalogs.

Ah. As to the calculations, since you had quoted rather precise figures I presumed you had worked them out.

I can give them later - when I am near a more practical typing instrument.

As for the turret ring, IIRC the base was designed as 2m. At some point it was 1.8m but I changed it for reasons I'm forgetting.

The M5 Stuart uses the 37mm M3 L56.6-L53.24 gun which uses a 37x223R AP shot with a rim diameter of 55.3mm.
The Lees and early Shermans used the 75mm M2/M3/M6 L31-L37.5-L39 gun which uses a 75x350R round with a rim diameter of 87mm.

The ideal cylinder volumes are then approximately 0.00054 m3 for the 37mm M3 gun and 0.00208 m3 for the 75mm M2/M3/M6 gun.

144 x 37x223R rounds takes a volume of 0.077 m3, with 2.5x margin it is 0.1944 m3.
24 x 75x350R rounds takes a volume of 0.05 m3, with a 2.5x margin it is 0.1248 m3.


By the way for the 7.5cm KwK 40 L48-L43 guns used on OTL German tanks:
The 75mm Kwk 40 uses a 75x495R round with a rim diameter of 111mm.
The ideal cylinder volume is 0.00479 m3.
24 x 75x495R rounds takes a volume of 0.115 m3, with 2.5x margin it is 0.2874 m3.

And the 76mm M1 L57-L52 gun used on the later Shermans.
The 76.2x539R rounds have a rim diameter of 93mm.
The ideal cylinder volume is 0.00366 m3.
24 x 76.2x539R rounds take a volume of 0.0879 m3, with 2.5x margin it is 0.2197 m3.

The 17pdr the British shoe-horned into the Sherman:
It had 76.2x583R rounds with a rim diameter of 135mm.
The ideal cylinder volume then is 0.0083 m3, with 24 x 76.2x583R taking up 0.5 m3 with margin.


Of course, the rounds are not ideal cylinder as they taper from rim to the projectile - so let's modify the calculations by using a tapering cylinder - the cylinder has a diameter the size of the rim diameter on one end and the projectile size on the other. Then the volume calculations are:

37x223R, 0.00038 m3 per, 0.13605 m3 for 144 with margin
75x350R, 0.00181 m3 per, 0.10841 m3 for 24 with margin
75x495R, 0.00340 m3 per, 0.20427 m3 for 24 with margin
76.2x539R, 0.00304 m3 per, 0.18239 m3 for 24 with margin
76.2x583R, 0.00524 m3 per, 0.31428 m3 for 24 with margin


[Presumption 1]
Since the 75mm KwK 40 has a similar penetration as the 76mm M1 gun, we can presume that the additional volume of the gun is necessary for the propellant to make up for the L11-L9 shorter barrel. As a naive analysis we could say we need an ideal cylinder volume roughly 31% larger or a tapered cylinder volume roughly 12% larger to have the same penetration properties for a barrel L11-L9 longer, assuming the barrels are not already so long that gas expansion properties are muted.

[Presumption 2]
Also, since the 17pdr APCBC penetration was roughly the same as the 76mm M1 HVAP penetration, we could naively say a 72% increase in tapered volume or 127% increase in cylinder volume yields the similar penetration as a HVAP round.

----------------------------------------------------

Now's let's try to determine the penetration properties of a 75mm L43 gun mounted on the L45E1-AB that would be equivalent to a 76mm M1 late Sherman gun as a mental exercise via tapered cylinder volume. I'm going to use the the 75x350R round as a base.

Let's presume that a two guns will have similar penetration if they have similar round volume, barrel length, and barrel diameter - Hence a 75mm L43 with 0.003 m3 per round is about the same as a 76mm L43 with 0.003 m3 per round.

The 75mm L43 is L12-5.5-4 longer than the 75mm M2/M3/M6 gun. Let's use the T45 HVAP as the base for what a 75mm HVAP would penetrate. I'm going to attribute the HVAP as a 75mm M3 round, i.e. the gun on the early Sherman, to make calculations more concrete, but there is no source for this.

The 75mm L43 is therefore L5.5 longer than a 75mm M3 L37.5 gun. From "Presumption 1" using L11, we could say it is equivalent to a round with roughly 6% larger volume. Supposing that the 75mm L43 on the L5E1-AB now also uses 66% more volume, from "Presumption 2" it would be roughly equivalent in penetration to a T45 HVAP round, ie 117mm RHA @ 30 degrees at 500 yards (457m).

That would make it slightly worse than a 75mm KwK 42 APCBC-HE (not APCR) round from the Panther and slightly better than the 76mm M1 APC round from the later Sherman.

It's volume would then be 0.00300 m3 per round, about the same as the 76mm M1 round, making it's total volume with margin as 0.18 m3.

-----------------

The actual round I had in mind is just a slightly larger 75x350R round with a longer barrel - +L5.5 vs the 75mm M3 on the early Shermans, hence the 0.13 m3 estimate. With the Presumptions factored in, it would be roughly equivalent to a 10% larger round. I would guess the penetration is somewhere in the vicinity of 80mm-90mm of RHA @ 30 degrees at 100 m. That makes it a rough 6pdr L50 equivalent but with better penetration at long range due to less energy drop.

Thank you for all the details. Very interesting and quite enlightening.