Jump to content
Sturgeon's House

COMPETITION Steel Chariot of The Prairie: The Lone Free State's First Battle Tank (2247)


 Share

Recommended Posts

Copying this from discord because it's important:
 

Quote

OK I have satisfied myself when it comes to tank mass
I used a dual approach, one in which I calculated the mass of the tank using Ogorkiewicz's simple ratio of armor, which gave me 65.55 m.t
the other in which I took the armor mass, and assuming a ratio of 0.43 for the tracks to the armor mass (assuming tracks make up 22% of the final weight and armor 51%, the ratio there being ~0.43), and then I added up everything from the Challenger sheet that wasn't already included
that method gave me 70.09 m.t
that second figure is a good thing as far as I'm concerned as the error mode for Ogorkiewicz's armor ratio is that it scales in mass some minor things that do not scale in mass with the mass of the tank, especially armor. For example, your tank's optical system will not need to be heavier if you have addon armor packages, nor will most of your hatches.
the fact that the second figure surpasses the ratio methodology suggests that, if the ratio gives you a high number, it's not so much higher that it will put you above, say, having shitty heavy bongistani fitments or something
these figures by the way was for Comanche's "light" version. The "heavy" version with meme wedges on the turret is about a ton more
so I wanted to post that to give the competitors a little more to go on when it comes to estimating weights. It seems that using Ogorkiewicz's method gives very fair numbers, overall
this also, it strikes me, explains a lot about why tanks today are heavy
if your ancillaries weigh that much, you actually don't have that much mass left over for armor. like it's the majority of the tank, but you need a lot of armor
if you say "well I want a a 45t tank" great, but you end up with Leopard 1 that dies instantly to 3BM4
there's nothing wrong with Leopard 1 of course, but if you would like to stop the rare and elusive T-62, then you need more armor
yeah I figured you especially will need it
what you will be absolutely required to do with your tank, Curly, is from the beginning dividing all your armor components by 0.51 and tracking your estimated final weight
if a turret/hull armor array is throwing you above your weight goal, then you will HAVE to redesign it
this is why that ratio is so useful, because it gives you a remarkably accurate picture of your final mass at a really early stage of design
if you want to make sure you hit a specific weight, then use a lower ratio like 0.46
for example the Chieftain sheet methodology gives me a ratio of 0.477
so it's not a done thing that you'll be at 0.51 by any means
one notes: this is absolutely brutal
I mean I didn't think I was a tank prodigy or anything, I just figured yeah, you get 2020 hindsight and you can make some improvements here and there. Now that I fully understand this accounting, I am impressed at what designers did before they had tools like Solidworks


Challenger sheet:

j6PXFwN.jpg

Link to comment
Share on other sites

14 hours ago, Fareastmenace said:

I'm actually interested in this.

For example, if a round penetrates the crew comptartment, but to immediately get absorbed by something non essential, do we consider that simply entering the crew compartment generate enough spall? And if so, what kind of spall cone can we expect?

Any penetration of crew compartment is armour failure, simple. Catching shrapnel between teeth is for the movies.

Link to comment
Share on other sites

On 5/27/2021 at 10:57 PM, Sturgeon said:

That's unbelievably light!

The armour is, shall we say, optimized. Thin base armour, ERA providing most of the actual value, and very narrowly directed to the specific threats.

 

I also just realised that I forgot to include the engine bay and covers, which bumps it over :wacko:

 

Luckily there's still a bit to shave off - the hull front and turret front are a bit more generous on KE than they strictly need to be.

 

Edit: so, after some judicious shaving which takes the frontal protection down to the bare minimum in terms of KE protection (16"), I've gotten the total armour weight down to 19.3t (17.5mt). The empty weight according to the software is 37.3t (33.9mt), but my expectation is that a full accounting of weight will push me all the way to my weight limit. 

Link to comment
Share on other sites

I am going to be introducing a new recommended weight accounting method to help standardize results between contestants, and to better prepare them for the judges' ire. This method is not mandatory, however it is strongly recommended, as it is expected to be the method by which the judges weigh (literally) each entrant against each other.

First, we are requiring in addition to the standard elements included on the submission sheet, that you include the armor mass of your tank in your submission. The armor mass includes any armor elements of your tank, including in addition to armor arrays, also structural elements like a cast or welded hull body, skirts, armored engine decks, hatches, etc.

Next, to calculate the combat weight of your tank (as outlined in the submission template), you take the armor mass of your tank, and multiply it by 0.45 to get the mass of suspension components for your tank (this includes tracks, roadwheels, sprockets, swing arms, idler tensioners, return rollers, etc). The reason for doing this is that as suspended mass increases, the mass of the suspension must increase also, meaning that in successful tank designs this ratio of about 0.45 stays remarkably constant (as detailed in Technology of Tanks). Then, add the armor mass and the suspension mass together with these figures:

Gun weight: (variable)
Ammunition weight: (variable)
Ammunition racks weight: (variable, but in the absence of a modeled weight for them, 1,700 lbs is a fine figure)
Gun stabilization system and gun electrics: 1,700 lbs for a ~4.7 inch gun (cubic scaling according to caliber, with minimum of 1,000 lbs)
Engine weight: (variable)
Transmission weight: (variable)
Fuel weight: (variable, but if you haven't modeled it for your tank, then use the value required to meet the range requirement)
Fuel system weight: 750 lbs
Electrical and environmental systems (combined): 3,500 lbs
Optics, sighting: 300-500 lbs (depending on complexity)
Fitments, stowage, and installed equipment: 7,500 lbs
Any other objects you've modeled, like cupolas etc: (variable)
Crew: 265 lbs per crewman

 

This means that if I have modeled a tank's armor, which weighs 18 tons for the hull and 12 tons for the turret (including arrays, engine deck, armored hatches, etc), my math will look like this:

18 + 12 = 30 tons hull (incl. skirts) and turret
30 x 0.45 = 13.5 tons suspension
13.5 + 30 = 43.5 tons hull, turret, and suspension
43.5 * 2,205 = 95917.5 lbs hull, turret, and suspension
95917.5 +
5300 lbs gun
2,650 lbs ammunition
1,700 lbs ammo racks
2,000 lbs gun stabilization and electrics
4,950 lbs engine
5,400 lbs transmission and final drives
3,660 lbs fuel
750 lbs fuel system
3,500 lbs electrical and environmental
500 lbs optics
7,500 lbs fitments, etc
265 lbs * 4 crew

=

134887.5 lbs combat weight for the tank, or 61.2 metric tons.

 

Link to comment
Share on other sites

Reposting this here for our contestants' reference
Height: 80mm plates making up 78% of perimeter, glacis making up 6%, rear (thinnest) 6%
Width: 25-37mm plates making up 81% of perimeter, glacis making up 19%
Length: 80mm plates making up 34% of perimeter, 25mm plates making up 66%
those are for Comanche's hull
also, only length adds track run
so if you need more volume, make your tank longer, and for the love of god do not make your tank hull taller
also you'll notice that raised engine decks are awesome

Link to comment
Share on other sites

Final Entry: Main Battle Tank, 2247, project name "Derebus"

 

7for5rn.jpg

 

Main dimensions and statistics

  • Manufacturer: Paramount-Allen-Fullerton (Para-allful) Conglomerated
  • Mass estimate (as based on CAD model plus ~6600lb to account for drive systems, crew amenities, ammunition and miscellaneous components): 43.1t (39.1mt) fully loaded, fueled.
  • Armour mass (1-2" (25-50mm) RHA base plus ERA, composites, side skirts and engine bay liner): 20.6t (18.5mt)
  • Calculated mass: 43.4t (39.4mt)
  • Crew: 4 (commander, gunner, loader, driver)
  • Length: 246" (6.25m) hull, 379" (9.63m) total 
  • Width:  150" (3.8m) with skirt
  • Height: 95" (2.41m) to top of commander's hatch, 109" (2.77m) total

 

xRy3O9X.jpg

Firepower


Note: the armour used for the target has the same hardness (360BRN) as the armour used in the vehicle. The target was at 0 degree obliquity for calculation purposes.

 

  • Main gun: 5-inch 55 calibre (127mm L/55) high/low pressure gun
  • “High pressure” = 70000 PSI (480 MPa) operating pressure, 14.16MJ energy.
  • Vertical travel: +15'/-10'

 

Ammunition:

  • 46lb (20.85kg) HEAT-FS, penetration of around 21" (535mm) using 122mm BK13 derivative (420mm if using BK13 penetration), 3074fps (937m/s), 9.14MJ using a low-pressure charge (~45k PSI).
  • 46lb (23.2kg) HE, (5.7kg) fill, estimated blast penetration of ~55mm RHA, 2910fps (887m/s)
  • Simple APFSDS (15:1 LD, 550BHN monosteel body, tungsten insert, 115mm cap, ring sabot): 1.57x23.54" (40x597mm) rod, 0.866x5.24" (22x133mm) insert, 14.2/5.2lb (5.6/3.2kg) penetrator/sabot mass, 1800m/s, 15.7/13.8" (400/350mm) penetration at 100/2000y.

 

Note: if following the design of 3BM-26, this could be higher in practice. Using DeMarre the estimated penetration is 17.1" (435mm) at 2000y. Upgraded monobloc projectiles could match and eventually improve on this, up to 25.6" (650mm) before needing to rework the ammunition storage.

 

Details:

 

  • Gun has a high-pressure and low-pressure recoil option, selectable on the slide – this doesn’t affect the recoil mechanism, it just changes where the trip key is to unlock the breech. Warning: don’t fire high-pressure ammo with the low-pressure setting selected!
  • Gun uses a separate 6.9x27" (175x685mm) charge: 44lb/20kg mass, semi-combustible case built along the lines of the 4Zh-40 charge used with the 2A26 gun), matching the length of the HEAT-FS round.
  • This charge gives space to produce a more powerful round to match higher future barrel higher pressures (when using a secondary charge with the APFSDS projectile itself). 74000 PSI (510 MPa) gives a potential power of 15MJ. 94000PSI (650 MPa) gives a potential power of 19MJ.
  • Final penetration potential of the gun with early monobloc DU projectiles is something in the region of 22" (550mm) at 2000y (putting it on par with Mango and Vant). Being able to store and handle a longer projectile (ie: above 27") would probably allow something a bit better than Snivets. 
  • Low-pressure charges are shortened (17.1" / 435mm) and come with an ejection spring to work with the same tubes as the high-pressure charges.

 

Storage:

  • 19 charges and 9 active projectiles (HE and HEAT) in armoured tubes in the turret. The tubes are sealed at the front and lead to a blast chimney that outlets to blow-off panels in the turret roof. 10 inert projectiles (APFSDS) are stored in various places in the turret space, held by retaining clips.
  • 16 charges and 8 active projectiles are stored on either side of the driver behind the fuel cells, also using the blast chimney approach (exhausting out the hull sides). 8 inert projectiles are stored in various spots in the hull.

 

Secondary weapons: 

  • .30cal MG as coax
  • Both the commander and loader’s hatch rotate and have mounts for .30 cal MGs.

 

Fire control:

  • Single axis stabilized gunner’s sight
  • Duel axis stabilized main gun
  • Vertical coincidence rangefinder (stadiametric, 39.4" (1m) base) which doubles as a redundant back-up sight.
  • Simple electronic gun-follows sight fire control system (encoder connected to sight mirror feeds elevation data into a transistor-based PID controller, which tries to match position on a similar encoder connected to the gun. When gun position and sight position align, the firing mechanism is electronically triggered).
  • Semi-autoloader: the loader places the charge and warhead on trays in the bustle. these are then fed into the gun using an automatic mechanism (horizontal rammer, pivoting loading tray and rigid chain actuator to ram the warhead and charge home). The gun automatically returns to the loading position after each shot. A short spring at the end of the actuator helps to smooth out the loading impulse.
  • LRF mounted above barrel.

 

Note: Industrial espionage has allowed Texan engineers to copy the laser rangefinder proposed for use in the Cascadian M8A1 upgrade package. The Texan copy of the LRS-2 ruby laser rangefinder uses a flashlamp-pumped ruby laser, optical sensor, quartz timing circuit and the sequential event time sampling approach (with post-sampling amplification) to allow time-of-flight rangefinding using a lower timebase and bandwidth compatible with current electronics. Solid state electronic components allow the system to be fairly compact and robust. The rangefinder features a numerical readout in the gunner’s station. The rangefinder has a maximum operating range of 5km in clear conditions and has an average estimation error of 1%. 

 

The TBC-3A ballistic computer and IAPO-3 sight were not copied, as the high velocity of the APFSDS used in the 5”/55 cal main gun was felt to provide sufficient accuracy when paired with a good rangefinder.

 

Mobility

DuxRMpb.jpg

  • Transverse-mounted Kharkiv V-2-derived engine (specifically the V-55 diesel): 600HP/448kW, 2248lb/1020kg dry weight. The engine has been slightly re-bored to 40l, but is otherwise mechanically very similar to the engine used on the historical T-62.
  • Hydraulic torque converter feeding into Merritt-Brown-style double differential system.
  • An alternate engine layout would be two V-6 engines of similar total displacement, mounted normally, with a combined linkage to the torque converter.
  • The engine, transmission and cooling system all sit in an aluminium tub that fits into a bay in the rear of the vehicle. This can be removed entirely for servicing, or to replace the powerpack with a different configuration.
  • Suspension: 20" (0.5m) ground clearance, geared torsion bar suspension, each axle pair in detachable units shrouded by aluminium housings. Wheels are 23.6" (0.6m) in diameter, with a track width of 27.6" (0.7m) and a pitch of 7.7" (0.195m).
  • Fuel load: ~2400lb total (639lb/290kg in tanks flanking the driver, 1764lb/800kg in rear sponson tanks, range of 490mi at 30mph
  • PWR: 13.8 HP/t (11.4 kW/mt)
  • Ground pressure (calculated MMP): 29.4 PSI (203 KPa). 
  • Track contact length: 153.5" (3.9m)
  • Track contact area: 58.8ft2 (5.46m2)
  • Nominal ground pressure (based on calculated weight): 10.3 PSI (70.77 KPa)

 

Protection

g2uyzV5.jpg

lJAa9j6.jpg
Notes:

  • Composite liner (50:50 HHA/textolite): density of 4.825g/cm3, layers of 0.2, 0.4, 0.6, 0.8 or 1" depending, with thickness adjusted to prefer the thickest possible layers (1"/1") with a thinner backing layer.
  • Mounting bolts for ERA layers are not modelled, but are accounted for.
  • The covers over the rear fuel cells are 1" RHA.

 

Turret front:

  • Two layers of L-ERA, sloped at 75’
  • Base armour: 1" (25mm) RHA sloped at 75’
  • 2.1" (55mm) composite (25mm HHA, 25mm textolite), sloped at 75’
  • KE: 16.9" (430mm)
  • CE: 89" (2250mm) vs single-charge. Tandem charge rated to penetrate both layers via precursor is something like 17.9/11.4" (455/290mm), corresponding to 3"/3" high/low-precision charges and a 4" form factor.

 

Turret cheeks:

 

Note: because of how the cheeks are sloped, protection actually drops off the closer you get to the 25’ arc.

 

  • Three layers of L-ERA sloped at 25’ in the horizontal
  • Base armour: 1" (25mm RHA), sloped at 25’ in the horizontal
  • 2.2" (55mm) composite, sloped at 25’ in the horizontal
  • KE: 11.4" (290mm) from the front
  • CE: 55" (1400mm) (normal) vs single charge. Tandem charge rated to penetrate both layers via precursor is something like 12.2/7.3" (310/185mm), corresponding to 2.1/2.4" (55/60mm) high/low-precision charges and a 3" form factor.

 

Turret side armour array:

  • Two layers of L-ERA sloped at ~30’ in the horizontal
  • Base armour: 1" (25mm) RHA, sloped at ~30’ in the horizontal
  • 1" (25mm) composite, sloped at 30’ in the horizontal
  • KE: 5.9" (150mm) at 30’ from side.
  • CE: 13.4" (340mm) at 30' from side. Maximum angle that side can resist 7" CE is ~20' from the side (70' from the front).

 

 

Turret rear:

  • 2" (50mm) RHA

 

Turret roof:

  • 1" (25mm) RHA

 

Hull upper front:

  • Two layers of L-ERA, sloped at 75’
  • Base armour: 1" (25mm) RHA sloped at 75’
  • 2.2" (55mm) composite, sloped at 75’
  • KE: 16.9" (430mm)
  • CE: 89" (2250mm) vs single-charge. Tandem charge rated to penetrate both layers via precursor is something like 17.9/11.4" (455/290mm), corresponding to 3" high/low-precision charges and a 4" form factor.

 

Hull lower front:

  • Base armour: 1" (25mm) RHA sloped at 45’ from vertical
  • 4.2" (106mm) composite, sloped at 45’ from vertical
  • KE: 7.3" (185mm)
  • CE: 7.5" (190mm) vs single-charge.

Notes: the area next to the driver contains two fuel cells and two protected storage areas for ammunition. Hits here are correspondingly much more protected than the above would indicate, for both the upper and lower hull.

 

Hull side:

  • 2 x L-ERA layers
  • Composite skirt: 0.2" (5mm) HHA with a 0.8" (20mm) textolite backing
  • 1" (25mm) aluminium roadwheel (depending on hit location)
  • 29.5" (750mm) air gap/fuel (depending on hit location)
  • Inner skin: 1" (25mm) RHA
  • KE: ~3" (75-80mm) (normal) / ~8.2" (190-225mm) (30’ arc from the front)
  • CE: ~3.8" (95-100mm) (normal) / ~30" (690-860) (30’ arc from the front)
  • Immunity zone against 15.7" KE: 21’ arc from front
  • Immunity zone against 7" CE: 54’ from front (36' from the side)

 

Notes: the upper hull side has numerous armoured brackets to hold the skirt. These would be expected to be hit when the impact is from the 30' arc, which would significantly improve protection.
 

Belly:

  • 1" 25mm RHA
  • 0-0.8" aluminium

 

Notes: the suspension units are aluminium boxes, the torsion bars are modelled as 2.75" (70mm) bars and each swing arm is attached to a hollow steel tube. The mine protection for the floor of the vehicle is accordingly expected to be much higher than these figures would indicate.

ZUANVSE.jpg

f0s5am8.jpg

Link to comment
Share on other sites

After finishing up on Derebus, the good folk at Para-allful Conglomerated decided to make a simplified model for the more down-scale customer:

lAfq1xi.jpg

The Derebus-M uses the 4" 40 cal low-pressure gun in an all-new turret. This, along with removing some of the nice-to-haves such as the coincidence rangefinder, complex fire control system and composite internal armour panels, allows the Derebus-M to be made cheaper, simpler and a bit lighter.

Link to comment
Share on other sites

15 minutes ago, Sturgeon said:

On the Derebus, it looks like the gun could be lowered a bit? That might save some height & mass.

 

Also what is your recoil stroke? For an MBT, 14-16" is pretty normal I think.

Recoil stroke is more or less exactly 14" (350mm). It might be worth trying to lower the main gun - IIRC the height was originally set so as to allow clearance for a tall hull periscope and to let the hatch rotate forwards. In the event I decided that the driver would prefer to open the hatch to look out of, so the hatch opens the other way.

Link to comment
Share on other sites

1 hour ago, Sturgeon said:

On the Derebus, it looks like the gun could be lowered a bit? That might save some height & mass.

 

Also what is your recoil stroke? For an MBT, 14-16" is pretty normal I think.

Thanks, that saved about 100kg...

Link to comment
Share on other sites

I'm basically ready, I just need to correct my mantlet because LMAO cleft turret and late modeled autoloader. So I might need one more day.

 

Toxn's tank looks really good, nice weight management.

Edited by Sten
Bees don't like sad camels, why do you want a reason for eddit?
Link to comment
Share on other sites

Final entry: Derebus-M

 

ykUMkdL.jpg

 

Main dimensions and statistics

 

Manufacturer: Paramount-Allen-Fullerton (Para-allful) Conglomerated

Mass estimate (as based on CAD model plus ~5830lb to account for drive systems, crew amenities, ammunition and miscellaneous components): 40.5t (36.8mt) fully loaded, fueled.

Armour mass (1-3.15" (25-80mm) RHA base plus ERA, composites, side skirts and engine bay liner): 21.5t (19.5mt)

Calculated mass: 41.9t (38mt)

Crew: 4 (commander, gunner, loader, driver)

Length: 246" (6.25m) hull, 261" (6.62m) total 

Width:  150" (3.8m) with skirt

Height: 86" (2.19m) to top of commander's hatch, 91" (2.30m) total

 

rTu3Mee.jpg

 

Firepower

 

Note: the armour used for the target has the same hardness (360BRN) as the armour used in the vehicle. The target was at 0 degree obliquity for calculation purposes.

 

Main gun: 102mm L/40 “4-inch 40 calibre” low-pressure gun:

“Low-pressure” = 310 MPa/3.45MJ

“Emergency” pressure = 345MPa/3.83MJ

Recoil stroke: 300mm

Vertical travel: +20/-10’

 

Ammunition:

  • 23.9lb (10.85kg) HEAT-FS, penetration of around 16.9" (430mm) using 122mm BK13 derivative (337mm if using BK13 penetration), 2614fps (797m/s).
  • 26.2lb (11.90kg) HE, 2.92kg fill, estimated blast penetration of ~1.4" (35mm) RHA, 2496fps (761m/s).
  • Simple APFSDS (15:1 LD, 550BHN monosteel body, tungsten insert, 76mm cap, ring sabot): 1x15.2" (26x387mm) rod, 0.55/3.4" (14x86mm) insert, 3.4/1.9lb (1.53/0.84kg) penetrator/sabot mass, 1800m/s, 10.3/9"(261/228mm) penetration at 100/2000y. Uses emergency pressure.

 

  • Case: 4x19.7" (102x500mm) steel case, 4.7" (120mm base), OAL (HEAT-FS) = ~28" (700mm)
  • Charge weight: 4.9lb (~2.2kg) standard, 5.4lb (2.46kg) emergency
  • Case weight: 11.5lb (5.2kg)
  • Overall weight (HEAT-FS): 40lb (18.25kg)

 

Note: if following the design of 3BM-26, this could be higher in practice. Using DeMarre the estimated penetration is 10.8" (274mm) at 2000y.

 

Storage:

21 rounds stored in an armoured storage bin in the turret. The bin exhausts through blow-off panels in the turret side and roof.

36 rounds stored in armoured bins on either side of the driver behind the fuel cells, with blow-off panels in the hull side and front

 

Secondary weapons: 

.30cal/7.62mm MG as coax

Both the commander and loader’s hatch rotate and have mounts for .30 cal MGs.

 

Fire control:

Single axis stabilized gunner’s sight (of the same configuration as Derebus).

Backup 60mm telescopic sight mounted to mantlet.

Duel axis stabilized main gun.

LRF (of the same configuration as Derebus) mounted above barrel.

 

YAmq6Z8.jpg

 

Mobility

 

2xV6 liquid-cooled diesels, 19l displacement each: 290hp/ 216kW each, 553kg dry weight each.

Combined output to hydraulic torque converter, feeding into Merritt-Brown-style double differential system.

The engine, transmission and cooling system all sit in an aluminium tub that fits into a bay in the rear of the vehicle. This can be removed entirely for servicing, or to replace the powerpack with a different configuration.

Suspension: 20" (0.5m) ground clearance, geared torsion bar suspension, each axle pair in detachable units shrouded by aluminium housings. Wheels are 23.6" (0.6m) in diameter, with a track width of 27.6" (0.7m) and a pitch of 7.7" (0.195m).

PWR: 13.8 HP/t (11.4 kW/mt)

Fuel load: ~2550lb total (793lb/360kg in tanks flanking the driver, 1764lb/800kg in rear sponson tanks, range of 540mi at 30mph

Ground pressure (calculated MMP): 28.4 PSI (196 KPa). 

Track contact length: 153.5” (3.9m)

Track contact area: 58.8ft2 (5.46m2)

Nominal ground pressure (using calculated mass): 9.86 PSI (68KPa)

 

yQKcJMt.jpg

mfZ3ayB.jpg

 

Protection

 

 

Notes:

Mounting bolts for ERA layers are not modelled, but are accounted for.

The covers over the rear fuel cells are 1" RHA.

 

Turret front:

Two layers of L-ERA, sloped at 75’

Base armour: 3.15" (80mm) RHA sloped at 75’

KE: 18.3" (465mm)

CE: 104" (2650mm) vs single-charge. Tandem charge rated to penetrate both layers via precursor is something like 17.9/12" (455/305mm), corresponding to 3"/3" high/low-precision charges and a 4" form factor.

 

Turret cheeks:

 

Note: because of how the cheeks are sloped, protection actually drops off the closer you get to the 25’ arc.

 

Three layers of L-ERA sloped at 25’ in the horizontal

Base armour: 3.15" (80mm RHA), sloped at 25’ in the horizontal

KE: 12" (305mm) from the front

CE: 56" (1425mm) (normal) vs single charge. Tandem charge rated to penetrate both layers via precursor is something like 12.2/7.3" (310/185mm), corresponding to 2.1/2.4" (55/60mm) high/low-precision charges and a 3" form factor.

 

Turret side armour array:

Two layers of L-ERA sloped at ~30’ in the horizontal

Base armour: 1" (25mm) RHA, sloped at ~30’ in the horizontal

KE: 5.9" (105mm) at 30’ from side.

CE: 13.4" (215mm) at 30' from side. Maximum angle that side can resist 7" CE is ~58' from the side (32' from the front).

 

 

Turret rear:

1.38" (35mm) RHA

 

Turret roof:

1" (25mm) RHA

 

Hull upper front:

Two layers of L-ERA, sloped at 75’

Base armour: 3.15" (80mm) RHA sloped at 75’

KE: 18.3" (465mm)

CE: 104" (2650mm) vs single-charge. Tandem charge rated to penetrate both layers via precursor is something like 17.9/12" (455/305mm), corresponding to 3"/3" high/low-precision charges and a 4" form factor.

 

Hull lower front:

Base armour: 5.15" (131mm) RHA sloped at 45’ from vertical

KE: 7.3" (185mm)

CE: 7.3" (185mm) vs single-charge.

Notes: the area next to the driver contains two fuel cells and two protected storage areas for ammunition. Hits here are correspondingly much more protected than the above would indicate, for both the upper and lower hull.

 

Hull side:

2 x L-ERA layers

25mm RHA skirt

1" (25mm) aluminium roadwheel (depending on hit location)

29.5" (750mm) air gap/fuel (depending on hit location)

Inner skin: 1" (25mm) RHA

KE: ~3.5" (85-95mm) (normal) / ~9" (210-245mm) (30’ arc from the front)

CE: ~4.2" (100-115mm) (normal) / ~32" (730-890) (30’ arc from the front)

Immunity zone against 15.7" KE: 21’ arc from front

Immunity zone against 7" CE: 56’ from front (34' from the side)

 

Notes: the upper hull side has numerous armoured brackets to hold the skirt. These would be expected to be hit when the impact is from the 30' arc, which would significantly improve protection.

 

Belly:

1" 25mm RHA

0-0.8" aluminium

 

Notes: the suspension units are aluminium boxes, the torsion bars are modelled as 2.75" (70mm) bars and each swing arm is attached to a hollow steel tube. The mine protection for the floor of the vehicle is accordingly expected to be much higher than these figures would indicate.

 

bv1RAou.jpg

0sWKOkd.jpg

 

Link to comment
Share on other sites

Still chipping away at the Brahman, just about ready to start modeling the armor. 

u6pJmLC.png

Spoiler

DS2sACm.png

 

If you're wondering how I'm going to protect the inlet and outlet to the engine, I'm going to use the same trick I used in the californium competition to protect the holes in the side, but slightly thicker. 

 

The plate above the engine is the radiator, which additionally has a 2 inch gap above and below it, where air is forced across it, to cool it. The exhaust and coolant air are both passed through the turbo charger, then through a CV90 type system, to cool it down and hopefully reducing the thermal signature. 

 

I'm going to access the engine and transmission via a similar system to the Merkava 4: the upper plate lifts up, using 2 hydraulic pistons powered by the tanks batteries; or if you need to pull the engine and tranny, you can lift off the upper plate with the same 5+ ton crane you need to lift the drive train. 

 

 

I need a little help, I don't know how to model a "modern" commanders cupola, with all the amenities, without making it too damn big. 

Link to comment
Share on other sites

1 hour ago, Lord_James said:

I need a little help, I don't know how to model a "modern" commanders cupola, with all the amenities, without making it too damn big. 

Use a low hexagonal prism as an all around periscopes

293px-Hexagonal_Prism.svg.png

Link to comment
Share on other sites

Math for mass:

wvSsLze.png

 

HJ3syqW.png
 

10227.98 kg turret armor + 16719.91 kg hull armor = 26947.89 kg

26947.89 kg * 0.45 = 12126.55 kg required mass of suspension components

12126.55 kg + 26947.89 kg = 39074.44 kg

My accessories, fittings, fuel, crew, etc weigh 38,970 lbs or 17,673.47 kg, so:

39074.44 kg + 17,673.47 kg = 56,747.91 kg, or 62.57 short tons.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

  • Similar Content

    • By N-L-M
      Restricted: for Operating Thetan Eyes Only
      By order of Her Gracious and Serene Majesty Queen Diane Feinstein the VIII
      The Dianetic People’s Republic of California
      Anno Domini 2250
      SUBJ: RFP for new battle tank
       
      1.      Background.
      As part of the War of 2248 against the Perfidious Cascadians, great deficiencies were discovered in the Heavy tank DF-1. As detailed in report [REDACTED], the DF-1 was quite simply no match for the advanced weaponry developed in secret by the Cascadian entity. Likewise, the DF-1 has fared poorly in the fighting against the heretical Mormonhideen, who have developed many improvised weapons capable of defeating the armor on this vehicle, as detailed in report [REDACTED]. The Extended War on the Eastern Front has stalled for want of sufficient survivable firepower to push back the Mormon menace beyond the Colorado River south of the Vegas Crater.
      The design team responsible for the abject failure that was the DF-1 have been liquidated, which however has not solved the deficiencies of the existing vehicle in service. Therefore, a new vehicle is required, to meet the requirements of the People’s Auditory Forces to keep the dream of our lord and prophet alive.
       
       
      Over the past decade, the following threats have presented themselves:
      A.      The Cascadian M-2239 “Norman” MBT and M-8 light tank
      Despite being approximately the same size, these 2 vehicles seem to share no common components, not even the primary armament! Curiously, it appears that the lone 120mm SPG specimen recovered shares design features with the M-8, despite being made out of steel and not aluminum like the light tank. (based on captured specimens from the battle of Crater Lake, detailed in report [REDACTED]).
      Both tanks are armed with high velocity guns.
      B.      The Cascadian BGM-1A/1B/1C/1D ATGM
      Fitted on a limited number of tank destroyers, several attack helicopters, and (to an extent) man-portable, this missile system is the primary Cascadian anti-armor weapon other than their armored forces. Intelligence suggests that a SACLOS version (BGM-1C) is in LRIP, with rumors of a beam-riding version (BGM-1D) being developed.
      Both warheads penetrate approximately 6 cone diameters.
      C.      Deseret tandem ATR-4 series
      Inspired by the Soviet 60/105mm tandem warhead system from the late 80s, the Mormon nation has manufactured a family of 2”/4” tandem HEAT warheads, launched from expendable short-range tube launchers, dedicated AT RRs, and even used as the payload of the JS-1 MCLOS vehicle/man-portable ATGM.
      Both warheads penetrate approximately 5 cone diameters.
      D.      Cascadian HEDP 90mm rocket
      While not a particularly impressive AT weapon, being of only middling diameter and a single shaped charge, the sheer proliferation of this device has rendered it a major threat to tanks, as well as lighter vehicles. This weapon is available in large numbers in Cascadian infantry squads as “pocket artillery”, and there are reports of captured stocks being used by the Mormonhideen.
      Warhead penetrates approximately 4 cone diameters.
      E.      Deseret 40mm AC/ Cascadian 35mm AC
      These autocannon share broadly similar AP performance, and are considered a likely threat for the foreseeable future, on Deseret armored cars, Cascadian tank destroyers, and likely also future IFVs.
      F.      IEDs
      In light of the known resistance of tanks to standard 10kg anti-tank mines, both the Perfidious Cascadians and the Mormonhideen have taken to burying larger anti-tank A2AD weaponry. The Cascadians have doubled up some mines, and the Mormons have regularly buried AT mines 3, 4, and even 5 deep.
      2.      General guidelines:
      A.      Solicitation outline:
      In light of the differing requirements for the 2 theaters of war in which the new vehicle is expected to operate, proposals in the form of a field-replaceable A-kit/B-kit solution will be accepted.
      B.      Requirements definitions:
      The requirements in each field are given in 3 levels- Threshold, Objective, and Ideal.
      Threshold is the minimum requirement to be met; failure to reach this standard may greatly disadvantage any proposal.
      Objective is the threshold to be aspired to; it reflects the desires of the People’s Auditory Forces Armored Branch, which would prefer to see all of them met. At least 70% must be met, with bonus points for any more beyond that.
      Ideal specifications are the maximum of which the armored forces dare not even dream. Bonus points will be given to any design meeting or exceeding these specifications.
      C.      All proposals must accommodate the average 1.7m high Californian recruit.
      D.      The order of priorities for the DPRC is as follows:
      a.      Vehicle recoverability.
      b.      Continued fightability.
      c.       Crew survival.
      E.      Permissible weights:
      a.      No individual field-level removable or installable component may exceed 5 tons.
      b.      Despite the best efforts of the Agriculture Command, Californian recruits cannot be expected to lift weights in excess of 25 kg at any time.
      c.       Total vehicle weight must remain within MLC 120 all-up for transport.
      F.      Overall dimensions:
      a.      Length- essentially unrestricted.
      b.      Width- 4m transport width.
                                                                    i.     No more than 4 components requiring a crane may be removed to meet this requirement.
                                                                   ii.     Any removed components must be stowable on top of the vehicle.
      c.       Height- The vehicle must not exceed 3.5m in height overall.
      G.     Technology available:
      a.      Armor:
      The following armor materials are in full production and available for use. Use of a non-standard armor material requires permission from a SEA ORG judge.
      Structural materials:
                                                                    i.     RHA/CHA
      Basic steel armor, 250 BHN. The reference for all weapon penetration figures, good impact properties, fully weldable. Available in thicknesses up to 150mm (RHA) or 300mm (CHA).
      Density- 7.8 g/cm^3.
                                                                   ii.     Aluminum 5083
      More expensive to work with than RHA per weight, middling impact properties, low thermal limits. Excellent stiffness.
       Fully weldable. Available in thicknesses up to 100mm.
      Mass efficiency vs RHA of 1 vs CE, 0.9 vs KE.
      Thickness efficiency vs RHA of 0.33 vs CE, 0.3 vs KE.
      Density- 2.7 g/cm^3 (approx. 1/3 of steel).
      For structural integrity, the following guidelines are recommended:
      For light vehicles (less than 40 tons), not less than 25mm RHA/45mm Aluminum base structure
      For heavy vehicles (70 tons and above), not less than 45mm RHA/80mm Aluminum base structure.
      Intermediate values for intermediate vehicles may be chosen as seen fit.
      Non-structural passive materials:
                                                                  iii.     HHA
      Steel, approximately 500 BHN through-hardened. Approximately twice as effective as RHA against KE and HEAT on a per-weight basis. Not weldable, middling shock properties. Available in thicknesses up to 25mm.
      Density- 7.8g/cm^3.
                                                                  iv.     Glass textolite
      Mass efficiency vs RHA of 2.2 vs CE, 1.64 vs KE.
      Thickness efficiency vs RHA of 0.52 vs CE, 0.39 vs KE.
      Density- 1.85 g/cm^3 (approximately ¼ of steel).
      Non-structural.
                                                                   v.     Fused silica
      Mass efficiency vs RHA of 3.5 vs CE, 1 vs KE.
      Thickness efficiency vs RHA of 1 vs CE, 0.28 vs KE.
      Density-2.2g/cm^3 (approximately 1/3.5 of steel).
      Non-structural, requires confinement (being in a metal box) to work.
                                                                  vi.     Fuel
      Mass efficiency vs RHA of 1.3 vs CE, 1 vs KE.
      Thickness efficiency vs RHA of 0.14 vs CE, 0.1 vs KE.
      Density-0.82g/cm^3.
                                                                vii.     Assorted stowage/systems
      Mass efficiency vs RHA- 1 vs CE, 0.8 vs KE.
                                                               viii.     Spaced armor
      Requires a face of at least 25mm LOS vs CE, and at least 50mm LOS vs KE.
      Reduces penetration by a factor of 1.1 vs CE or 1.05 vs KE for every 10 cm air gap.
      Spaced armor rules only apply after any standoff surplus to the requirements of a reactive cassette.
      Reactive armor materials:
                                                                  ix.     ERA-light
      A sandwich of 3mm/3mm/3mm steel-explodium-steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).
                                                                   x.     ERA-heavy
      A sandwich of 15mm steel/3mm explodium/9mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 3 sandwich thicknesses away from any other armor elements to allow full functionality. 81% coverage (edge effects).
                                                                  xi.     NERA-light
      A sandwich of 6mm steel/6mm rubber/ 6mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.
                                                                 xii.     NERA-heavy
      A sandwich of 30mm steel/6m rubber/18mm steel.
      Requires mounting brackets of approximately 10-30% cassette weight.
      Must be spaced at least 1 sandwich thickness away from any other armor elements to allow full functionality. 95% coverage.
      The details of how to calculate armor effectiveness will be detailed in Appendix 1.
      b.      Firepower
                                                                    i.     2A46 equivalent tech- pressure limits, semi-combustible cases, recoil mechanisms and so on are at an equivalent level to that of the USSR in the year 1960.
                                                                   ii.     Limited APFSDS (L:D 15:1)- Spindle sabots or bourelleted sabots, see for example the Soviet BM-20 100mm APFSDS.
                                                                  iii.     Limited tungsten (no more than 100g per shot)
                                                                  iv.     Californian shaped charge technology- 5 CD penetration for high-pressure resistant HEAT, 6 CD for low pressure/ precision formed HEAT.
                                                                   v.     The general issue GPMG for the People’s Auditory Forces is the PKM. The standard HMG is the DShK.
      c.       Mobility
                                                                    i.     Engines tech level:
      1.      MB 838 (830 HP)
      2.      AVDS-1790-5A (908 HP)
      3.      Kharkov 5TD (600 HP)
                                                                   ii.     Power density should be based on the above engines. Dimensions are available online, pay attention to cooling of 1 and 3 (water cooled).
                                                                  iii.     Power output broadly scales with volume, as does weight. Trying to extract more power from the same size may come at the cost of reliability (and in the case of the 5TD, it isn’t all that reliable in the first place).
                                                                  iv.     There is nothing inherently wrong with opposed piston or 2-stroke engines if done right.
      d.      Electronics
                                                                    i.     LRFs- unavailable
                                                                   ii.     Thermals-unavailable
                                                                  iii.     I^2- limited
      3.      Operational Requirements.
      The requirements are detailed in the appended spreadsheet.
      4.      Submission protocols.
      Submission protocols and methods will be established in a follow-on post, nearer to the relevant time.
       
      Appendix 1- armor calculation
      Appendix 2- operational requirements
      Addendum 1 - more armor details
      Good luck, and may Hubbard guide your way to enlightenment!
    • By Sturgeon
      @Toxn
      @Dominus Dolorem
      @Lord_James
      @A. T. Mahan
      @delete013
      @Sten
      @Xoon
      @Curly_
      @N-L-M
      @Sturgeon
       
      detailed below is the expected format of the final submission.
      The date is set as Saturday the 24th of July at 23:59 CST.
      Again, incomplete designs may be submitted as they are and will be judged as seen fit.

      PLEASE REMEMBER ALL ENTRIES MUST BE SUBMITTED IN USC ONLY
       
       
      FINAL SUBMISSION:
      Vehicle Designation and name
       
      [insert 3-projection (front, top, side) and isometric render of vehicle here]
       
      Table of basic statistics:
      Parameter
      Value
      Mass, combat (armor)
       
      Length, combat (transport)
       
      Width, combat (transport)
       
      Height, combat (transport)
       
      Ground Pressure, zero penetration
       
      Estimated Speed
       
      Estimated range
       
      Crew, number (roles)
       
      Main armament, caliber (ammo count ready/stowed)
       
      Secondary armament, caliber (ammo count ready/stowed)
       
       
      Vehicle designer’s notes: explain the thought process behind the design of the vehicle, ideas, and the development process from the designer’s point of view.
      Vehicle feature list:
      Mobility:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Engine- type, displacement, rated power, cooling, neat features.
      3.     Transmission - type, arrangement, neat features.
      4.     Fuel - Type, volume available, stowage location, estimated range, neat features.
      5.     Other neat features in the engine bay.
      6.     Suspension - Type, Travel, ground clearance, neat features.
      Survivability:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Link to Appendix 2 - armor array details.
      3.     Non-specified survivability features and other neat tricks - low profile, gun depression, instant smoke, cunning internal arrangement, and the like.
      Firepower:
      A.    Weapons:
      1.     Link to Appendix 1 - RFP spreadsheet, colored to reflect achieved performance.
      2.     Main Weapon-
      a.      Type
      b.      Caliber
      c.      ammunition types and performance (short)
      d.     Ammo stowage arrangement- numbers ready and total, features.
      e.      FCS - relevant systems, relevant sights for operating the weapon and so on.
      f.      Neat features.
      3.     Secondary weapon - Similar format to primary. Tertiary and further weapons- likewise.
      4.     Link to Appendix 3 - Weapon system magic. This is where you explain how all the special tricks related to the armament that aren’t obviously available using 1960s tech work, and expand to your heart’s content on estimated performance and how these estimates were reached.
      B.    Optics:
      1.     Primary gunsight - type, associated trickery.
      2.     Likewise for any and all other optics systems installed, in no particular order.
      C.    FCS:
      1.     List of component systems, their purpose and the basic system architecture.
      2.     Link to Appendix 3 - weapon system magic, if you have long explanations about the workings of the system.
      Fightability:
      1.     List vehicle features which improve its fightability and useability.
      Additonal Features:
      Feel free to list more features as you see fit, in more categories.
      Free expression zone: Let out a big yeehaw to impress the world with your design swagger! Kindly spoiler this section if it’s very long.
       
       Example for filling in Appendix 1
       Example for filling in Appendix 2
       Example for filling in Appendix 3

      GOOD LUCK!
    • By Monochromelody
      IDF had kept about 100 Tiran-6/T-62s since 1973, and remain service until 1990s. 
       
      I wonder if there's any modification on Tiran-6, like changing the powerpack into 8V71T+XTG-411, adapting steering wheel. 
       
      I also heard that British ROF had produce a batch of 115mm barrel for IDF, while MECAR or NEXTER produced high-performance APFSDS for 115mm gun. Did IDF really use these barrels for original barrel replacement? 
       
      And about protection, did IDF put Blazer ERA on Tiran-6? Or they use more advanced APS like Trophy? 
       
      Thank you. 
×
×
  • Create New...