Competition: Californium 2250

[Toxn]

7 minutes ago, Sturgeon said:

 

Well the T-10M's main gun can do it. 

I honestly forgot about the T-10M...

[Xoon]

Been refining the suspension, currently done with the suspension arm:

 

Next on the agenda is the suspension mount:

Currently work is progress. 

 

 

 

 

This is all I am going to do today, its waaay to late:

[Toxn]

I don't have access to my primary computer for a while, so I've been dicking around on my laptop:

This is Big Bouy, which has two AVDS engines, a 200mm gun, and an exceedingly low likelihood of being a sensible weight.

[Zyklon]

объект Papa smurf?

[Toxn]

37 minutes ago, Zyklon said:

объект Papa smurf?

Object 958...

[N-L-M]

Haze Gray has been approved for vehicular camouflage.

[Lord_James]

Update on the SH-1T: 

 

Mock-up of turret

Extended sponsons 

gun created (and roughly placed within turret) 

 

 

Spoiler

 

 

 

 

weight thus far is 48.27 Mg; length is 10.74m from barrel tip to rear storage; autoloader can fit 24 155mm x 800mm shells, but I designed it for 900mm long shells, so might fit 22 or so. 

 

Turret Armor Cavities: 

 

Front: 45mm RHA + 515mm array + 90mm JPA at 30^o. 751mm LoS from dead front. 

Front Sides: 45mm RHA + 255mm array + 63mm JPA. At 45^o, LoS is 513mm (covers turret crew up to 60^o). 

Rear Sides: 35mm RHA + 101.5mm array + 45mm RHA. 257mm LoS at 45^o. 

 

Gun is the 155mm C4B Mod.3 naval cannon. The B version of the C4(x) is an L/44 (C4A is a L/52), and the Mod.3 is modified for army use. It has a bayonet locked barrel for quick changing, and can fire up to 900mm long projectiles, but the chamber is limited to 800mm long propellant charges. Operates at 61,000 psi (421 MPa) and has a 500mm recoil stroke. 

 

Crew is estimated at 5: 

 

Driver 

Loader 

Gunner

Commander

Ordinance operator / Assistant loader (I plan to add a remote 107mm mortar, which this crewperson would use) 

 

I found that I can increase head room / lower the floor if I remove the 6th pair of road wheels, revise the floor armor,  and drop the autoloader into the space. Should give back ~100mm. 

 

 

To do: 

 

H. Mantle armor 

I. Add spaces for stuff to go into sponsons 

J. The engine and transmission 

K. Turret roof armor 

L. Additional weapons (coax, 107mm mortar, commander armament, etc.) 

[Toxn]

I managed to mail myself the file for Brick junior and got working on upgrades:

 

Xer now has the high-powered 133mm L/50 gun, which was developed specifically to beat the base Norman armour spec out to 2000m using AP-FS. The dimensions of the cartridge are compatible with the existing 150mm one in terms of ammo rack space, so the ammunition load is the same. The new gun also has a muzzle break and fume extractor, both of which are more to allow compatibility with other projects than anything else.

 

The Brick jr now also has a larger 16-cylinder AVDS-derived engine, which should put out around 1200HP. The weight will have gone up by a few tonnes (I haven't recalculated all the values again), but this should be more than offset by the increased power.

 

I think Brick jr is more or less in xer's final form now, and will work on the backup project (which is supposed to use a more conventional turret) for the next little while. 

[Collimatrix]

On 4/6/2019 at 12:53 PM, Toxn said:

So in case anyone is wondering (not that I'm advocating anything for or against anything), the minimum specs needed to punch through 203mm RHA sloped at 20' degrees from vertical at 2000m is:

- 122m gun, ~12.3MJ muzzle energy

- 25kg APBC, 992m/s (mass and penetration based on 122mm BR-471D)

 

So this can in principle be achieved using a hot D-25T

 

 

*Looks around carefully to make sure that no auditors are in the room*

*Checks the room carefully for SeaOrg bugs (which are easy to locate because they are clearly labeled "SeaOrg")*

 

OK, just pointing out that if you make a gun that just barely meets Her Serene Majesty's requirements, it can't actually kill the Norman.  Her Gracious and Serene Majesty doesn't actually know anything about tanks.

 

Per the OP, the Norman has 330mm of protection against KE, and per the final post from the previous competition, that was clearly intended as an interim and easily removable armor array to be used until a proper composite armor array could be supplied instead.

 

For 330mm of penetration at combat distances with full caliber AP, you're looking at something a bit more powerful than the M58, and ideally with better-designed shells.

[Xoon]

 

I might run with such a suspension design, seems more leak proof than a vane motor. 

 

Honestly, I might be putting way to much time into the suspension unit, but hey, at least I know how pretty much all the hydropneumatic suspension units work in AFVs. 

[Toxn]

57 minutes ago, Collimatrix said:

 

 

*Looks around carefully to make sure that no auditors are in the room*

*Checks the room carefully for SeaOrg bugs (which are easy to locate because they are clearly labeled "SeaOrg")*

 

OK, just pointing out that if you make a gun that just barely meets Her Serene Majesty's requirements, it can't actually kill the Norman.  Her Gracious and Serene Majesty doesn't actually know anything about tanks.

 

Per the OP, the Norman has 330mm of protection against KE, and per the final post from the previous competition, that was clearly intended as an interim and easily removable armor array to be used until a proper composite armor array could be supplied instead.

 

For 330mm of penetration at combat distances with full caliber AP, you're looking at something a bit more powerful than the M58, and ideally with better-designed shells.

*Casually chats about the weather after we 'happen' to bump into each other outside in the park (on a suitably windy day) until I'm certain that nobody else is nearby*

 

I'm fully aware of that. Which is why my 133mm gun, which is what I'm actually putting on my tank right now, does 360mm from 2000m. Which most certainly can kill a Norman, and can probably kill an uparmoured one from a bit closer to even with full-bore stupidity rounds. If you look at my other gun (the 150mm piece) it is and was always optimised for HEAT and the AP round we lashed together barely punches through 200mm on the flat at distance. And even that took a painful redesign of the gun and its cartridge.

 

I'm making other people aware of the minimum level of gun needed so they can go about their day unmolested and then say 'whoops, guess what we just happened to have lying about' when a certain someone succumbs to her increased stress levels and ever-harder-to-hide amphetamine addiction and we can all use finned sabot again.

 

Barring that, a 122mm gun slinging our most up-to-date tandem HEAT-FS can do 200/500mm. Meaning that it will go through a Norman with bolt-on ERA like butter until such time as the perfidious Cascadians add in a NERA interlayer.

 

Finally; if you run the numbers on a fully upgraded Norman (ie: with the bolt-on RHA removed and NERA/ERA added all over the shop) you'll find that nothing short of 550+mm of KE or something like a 190mm diameter tandem HEAT shell has any hope of killing it from the front. Which means that either you sling APFSDS and damn the consequences, or resign yourself to throwing artillery shells at the thing and hope that Her Serene Majesty won't notice that the turret got pulled off by explosive mass rather than any sort of armour piercing effect.

[Toxn]

So I think I just T-72'd myself.

 

The backup is looking really, really good.

 

Edit: really, really, really good

It developed from the same philosophy that informed the Big Buoy tank concept, so it's been provisionally dubbed 'Lil Buoy after the pre-war mythological figure.

 

So far the weight estimates have it at 71mt fully loaded, with the same 133mm gun and stretched AVDS-derived engine as the Brick (2950kg dry mass, 1205HP). This gives it a power-to-weight ratio of just under 17HP/mt, which should bump it over the minimum requirements in that department. It also has the same autoloader setup as the Brick, with 20 complete rounds in left side of the turret and another 10 in the left front ammo rack. If needed, the turret crew can now manually serve the gun (although this would obviously only be in case of emergencies or malfunctions).

 

The gun itself fires AP-FS, HE-FS and various types of HEAT-FS. The AP-FS can comfortably exceed the new penetration requirements, to the extent that it can penetrate the turret armour of a Norman-series tank from the front at 2000m.

 

133mm ammunition:

• Common: seperate propellant and warhead stages, semi-combustible cases. The propellant stage is 150x1000mm and has a steel case stub. The warhead stage is 133x1000mm bottlenecked to 150mm at the base. Warhead stages may have extra propellant.
• AP-FS: 34kg, 960m/s, 265mm RHA penetration at 2000m (130mm BR-482B used as reference)
• HE-FS: 35kg, 835m/s, ~45-50mm RHA penetration
• HEAT-FS (single, steel cone): 35kg, 835m/s, 430mm RHA penetration
• HEAT-FS (tandem, copper cone, improved explosives and pressing, higher cone precision, wave shaper, improved detonators etc): 35kg, 835m/s, 230/615mm RHA penetration

[Lord_James]

Just to clarify (because I suffer from autism): you multiply the actual thickness of the material by the TE modifier and this gives you the RHAe of that material, right? 

[N-L-M]

Yes.

[Collimatrix]

OK, time to look at the current and potential future armor of the Cascadian Entity's "Norman" tank.  Sadly, ink supplies of the official Comic Sans typeface ran out, so we had to switch to Times New Roman for the remainder of this communique:

 

Her Gracious and Serene Majesty Queen Diane Feinstein the VIII has charitably appropriated more earth conscious ink for this post

 

The Norman has 8-10 degrees of gun depression, so it probably gets shot in the turret a whole lot.  Any armament that cannot reliably penetrate the turret can't really be said to reliably kill it.

 

We know that the existing Norman has a turret array of 50mm base RHA, 150mm of bolt-on RHA (sitting on a rubber mounting surface, which is assumed to have negligible impact here), a 100mm air gap, and 60mm of HHS on top of that.  Running the equation backwards; (50 + 150) x 1.1 +60 x 2, we get 340mm vs HEAT, and 330mm vs KE.

 

But the original Norman submission was very clear that this is a temporary expedient:

 

Quote

The base steel is not homogenous; on the turret cheeks and sides, and on the hull front, it is an arrangement that can only adequately be described as “inverse Stillbrew”. The armor comprises a 50mm thick base layer, with the secondary casting bolted on with a rubber interlayer in the middle. The purpose of this arrangement is not to increase protection (although it should a bit), but rather to aid upgradeability- when better armor gets developed, it is intended that the thick steel facing plates be swapped for more weight-efficient armor. The volume needed for these arrays is already available, as the spaces of the spaced armor. The stowed equipment in those pockets will be displaced to less critical locations.

 

Ruh Roh.

 

Quote

It is intended that with the steel armor replaced by NERA arrays and the external face topped with ERA, that the total armor array will be ERA-hard armor-NERA-backing steel armor.
Such an array is reminiscent of the T-72BV turret and could quite reasonably be expected to handle tandem HEAT and moderately advanced APFSDS constructions. This drastic improvement in protection could easily be a simple part of a midlife upgrade, with the chosen construction methods.

 

So, there will be a 50mm base, a ~250mm pocket filled with NERA (let's assume it's similar to Californian H-NERA, since that is the most similar to the T-72B), 60mm HHS and light ERA on top of that for this planned upgrade.

What we would really like to know is the angle of the angle of the armor plates within this array.

 

 

In general, we can assume that the Cascadian armor scientists aren't stupid.  Furthermore, they operate within a sane and reasonably effective management structure, which goes a long way to explain the recent defections.

 

The optimal obliquity for H-NERA is quite high.  Furthermore, the spacing requirements for H-NERA are large, with 54mm of distance between the sandwiches required, as measured normal.  If the bulge zone overlaps with the armor box a little at the edges, that's probably not a problem because the edge of NERA arrays don't really work correctly anyways.  Therefore, as a simplifying assumption, the arrays will reasonably run all the edge of the box they live in until their corners touch.

 

The limit on plate obliquity within the box will be the angle at which the gap between the layers of H-NERA are wide enough that a projectile could pass between them without hitting one.  Or rather, a bit less than this, because, again, the edges of a NERA array don't really do anything.  Using a quick sketch in a CAD program my 1337 trig skills, I determine that the armor can be at up to 61 degrees from the vertical before such gaps appear.

 

But realistically, it's going to be a bit less than that, so that the ineffective edges of the H-NERA overlap a bit more.  Let's say 57 degrees from the vertical.

 

There is also the question of whether the strike faces of these arrays will be tilted up or tilted down.  Tilted up seems more likely to me because, although this sacrifices effectiveness against plunging fire, it increases effectiveness against direct fire when hull down.

 

Single-layer L-ERA will probably be placed at maximum practical obliquity to get the most performance out of a single layer of protection.  Let's say 70 degrees, and assume that any containers for this ERA will have negligible ballistic effect.

 

So, inside to out that's 50mm RHA, H-NERA inclined at 57 degrees, 60mm HHA, L-ERA inclined at 70 degrees:

 

I get that such an array protects 393mm vs KE and 749mm vs CE.'

 

And that's just the planned upgrade.  If they lop off the somewhat inefficient leading HHS and expand the array out to where it starts to be a problem for driver's hatch clearance, they can easily get arrays north of 450mm vs KE and 1000mm vs CE.

 

So, getting a gun big enough to actually force the Cascadians back to the drawing board is non-trivial.

 

 

So, with that out of the way, I have two questions:

1)  What are the parameters for gas turbines?

2)  What are the parameters for PELE rounds?  The DM-33 derivative PELE round has 1/3 the penetration of the APFSDS round it's based on.  Does 1/3 penetration seem like a reasonable multiplier for PELE rounds?

[Lord_James]

1 hour ago, Collimatrix said:

2)  What are the parameters for PELE rounds?  The DM-33 derivative PELE round has 1/3 the penetration of the APFSDS round it's based on.  Does 1/3 penetration seem like a reasonable multiplier for PELE rounds?

 

Is the reduction in penetration due to the reduction in mass and less dense materials, or is there another reason? 

[N-L-M]

29 minutes ago, Collimatrix said:

a 100mm air gap,

 

Checking the model, apparently that's selling the turret a bit short. The turret cheeks are 170 deg thick and set 35 deg off the centerline, topped with a 164mm air gap and then 60mm HH face.

From dead ahead that's 297 RHA-286mm gap- 104mm HH

And from 30 deg off to the side it's 187 RHA-180 gap-66 HH.

 

The turret sides are 100mm RHA-120mm gap- 30mm HH

and at 30 deg off centerline are 200mm RHA-240mm gap- 60 HH

 

So the NERA cavities would be 284 mm on the cheek (313mm LOS at +30 deg), and 170mm (340 mm LOS at +30) on the sides.

The turret nose can accommodate some pretty beefy arrays on the production Norman without overly disturbing the driver too-

The production Norman has a slightly rearranged driver's hatch area (for improved visibility), and a slightly rearranged mantlet area (and an actual mantlet, once I get around to modelling the thing):

The upgraded armor of the Norman would have light NERA in the pockets, and heavy ERA (possibly topped with light ERA as well) on the outside.

I may math out just how effective the Cascadian array is at some point, too.

 

 

1 hour ago, Collimatrix said:

1)  What are the parameters for gas turbines?

2)  What are the parameters for PELE rounds?  The DM-33 derivative PELE round has 1/3 the penetration of the APFSDS round it's based on.  Does 1/3 penetration seem like a reasonable multiplier for PELE rounds?

The DPRC's jet engine tech is sufficiently advanced to produce P&W JT3D engines and equivalents.

PELE at 1/3 sounds reasonble.

[Collimatrix]

4 hours ago, Lord_James said:

 

Is the reduction in penetration due to the reduction in mass and less dense materials, or is there another reason? 

 

The total sectional density is reduced, and also more of the axial momentum of the projectile turns into radial momentum:

 

[Toxn]

16 hours ago, Collimatrix said:

So, getting a gun big enough to actually force the Cascadians back to the drawing board is non-trivial.

Yeah, no kidding.

 

I actually had to downgrade my 133mm gun a bit, as checking it against the available pressure limits for 2A46 (510 MPa for earlier versions of the gun) showed that it was going over. Bear in mind that this configuration was selected precisely because it has the maximum possible penetration using conventional AP. So, for instance, if you run a similarly pressure-limited 152mm AP shell (based on BR-540B), you get something like 216mm RHA penetration at 2000m.

 

Edit: hold the fucking phone, because I just had an idea. I'll revert if/when something comes of it.

 

Edit 2: Okay, here it is

I'm calling it the "Sustainer" shell. It's essentially a rocket motor and shell wrapped around a completely conventional armour-piercing core. The shell has a set of folding fins on the back, while the core has a small tungsten bit on the front.

 

Testing using Rocketsim lots of math by actual rocket scientists shows that the entire assembly would weigh around 12.5kg and produces enough thrust to hit over 500m/s from a standing start. Behind the shell is a buffer pad to keep the entire thing from disintegrating, and behind that a powder charge. The entire thing is loaded as a warhead section in front of a standard propellent charge and shot out of the gun at around 1580m/s. From there on the rocket motor kicks in and actually speeds the projectile (potentially up to around 1900m/s) before simply sustaining the velocity.

 

Penetration is accordingly a bit weird, starting off at around 300mm RHA equivalence at the muzzle, and then rising to perhaps 395mm a kilometre and a half out. From there it holds more-or-less steady out to 4km, before rapidly dropping off.

 

This new type of shell, which we're thinking of referring to as "Rocket-assisted AP, Fin-Stabilised" (or RAP-FS) is expected to provide substantial penetration performance while maintaining a non-phallic, mammaric appearance.

[Kal]

During 1960s Dow's magnesium from seawater extraction plants in Texas had about 100,000 tonnes capacity annually.  Up from 50,000 circa 1941.

 

Can we use magnesium? Early BMPs were magnesium.  I would approximate keeping equal mass efficiency between cast Mg and wrought Al.

[N-L-M]

1 hour ago, Kal said:

Texas

The Lone Free State of Texas is not assessed as being a threat to the DPRC at the current time being a significant distance away, but your ambitions to conquer their industrial base are lauded.

 

Magnesium alloys with similar mass efficiency to Aluminum are acceptable.

[N-L-M]

6 hours ago, Toxn said:

Edit 2: Okay, here it is

That's going to need a significantly more massive body-rod interface to avoid having it leave the LR behind, which means more parasitic mass.

Also, the body will require significantly thicker walls to survive the stresses of launch at the stated pressures, which again means more parasitic mass.

Other than that, however, DPRC PAF-Ordnance approves, but would like to know what rocket fuel is intended to be used.

 

On a brighter note, such a shell would have significant incendiary effects pre-burnout.

[Collimatrix]

6 minutes ago, N-L-M said:

On a brighter note, such a shell would have significant incendiary effects pre-burnout.

 

That's a heroic understatement.

[Toxn]

15 minutes ago, N-L-M said:

That's going to need a significantly more massive body-rod interface to avoid having it leave the LR behind, which means more parasitic mass.

Also, the body will require significantly thicker walls to survive the stresses of launch at the stated pressures, which again means more parasitic mass.

Other than that, however, DPRC PAF-Ordnance approves, but would like to know what rocket fuel is intended to be used.

 

On a brighter note, such a shell would have significant incendiary effects pre-burnout.

The design is, shall we say, provisional. I would appreciate any guidance you or anyone else may have on how best to configure the round, as I'm well outside of my sphere of knowledge here and working with fairly limited tools.

 

The propellant for the rocket is some version ammonium perchlorate composite, for which a wealth of surviving literature exists.

[N-L-M]

6 minutes ago, Toxn said:

ammonium perchlorate composite

Approved for use.