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

[Sturgeon]

Protection for Comanche is rated for 13 inches (3BM6+) throughout the +20/-20 degree frontal arc with very minimal weakspots (slits, etc) only. At any place on the tank 90 degrees to the side, it will repel the Mormon 6" HEAT weapon. Coincidentally, as a byproduct of a weight-saving and turret-balancing measure, the turret will also repel the 6" HEAT weapon from the rear. Roof is rated for plunging fire. Bottom armor is rated at 1.25" RHAe vs mines and blast.

Armament is a 5in-24 load-assisted, high velocity rifled cannon firing very low drag high L:D APDS from combustible cases at 4,800 ft/s (as a fun challenge, spot the problem with this scheme). Penetration at 2,000 yards is calculated to be approximately 15.7 inches against a plate at 60 degrees from normal. The gun can elevate 20 degrees and depress 10 degrees, and has a rotational arc of 243.2 degrees with the gun at full depression. Coaxial armament consists of 1x .30 caliber G-17A5T machine gun and 1x .50 caliber G-19A2T machine gun, which are slaved to the main gun. Independent armament consists of 1 additional G-17A5 and 1 additional G-19A2 machine gun, and 2 dual close-in .40 caliber G-346E1 machine guns. Ammunition stowage is 1,200 rounds of .50 caliber ammunition, 10,000 rounds of .30 caliber ammunition, and 3,000 rounds of .40 caliber ammunition.

Power is provided by a liquid-cooled 12-cylinder diesel engine with 2,850 cu in displacement, putting out 1,200 horsepower and up-rateable to 1,500 horsepower. Power to weight ratio is 19.2 hp/tonne at basic engine rating. Top speed is 50 miles per hour on roads, 30 miles per hour off-road. Cruising speed is 40 miles per hour.

[Sturgeon]

New gun and fin round:

 

 

Powley:

 

DeMarre:

 

the new ammunition is substantially lighter and so is the gun, which saves us 840 lbs! Hooray!

So the current weight is 62.15 short tons.

 

[A. T. Mahan]

We're allowed combustible cases? I thought we had to stick with steel cased main gun ammunition

[Sturgeon]

3 hours ago, A. T. Mahan said:

We're allowed combustible cases? I thought we had to stick with steel cased main gun ammunition

 

Steel cases are available but you can use other technology of the period. e.g., bag charges. High energy combustible cases are, however, not available.

[Sturgeon]

Because @Dominus Dolorem complained that Comanche looked too much like an Abrams, I decided to make it look more like an M1... Specifically, a GM XM1! MUAHAHAHAH!

[Sturgeon]

 

Quote

An XG-49E3 Comanche tank stops by a convenience store in Grano, North Dakota for refreshments during automotive endurance trials, sporting the distinctive "Jackson Pollack" camouflage. June, 2250.

 

[delete013]

Promo shot from the recent ergonomics testing.

[Sturgeon]

Obviously we're ten days past the "deadline". It seems everyone is still working. I'm happy if you're happy.

[delete013]

I finished the painful weight calculation. I likely will finish this weekend.

[Toxn]

46 minutes ago, delete013 said:

I finished the painful weight calculation. I likely will finish this weekend.

Good going!

We'll look forward to your entry.

[Sturgeon]

Greeble get!

[Lord_James]

Idk if I’m going to make it. Don’t postpone the competition, it’s been pushed back enough, just don’t be surprised if I don’t submit something. 

[Sturgeon]

1 hour ago, Lord_James said:

Idk if I’m going to make it. Don’t postpone the competition, it’s been pushed back enough, just don’t be surprised if I don’t submit something. 

 

We're not really too worried about the deadline. It's just there to get people going a bit.

[Lord_James]

11 hours ago, Sturgeon said:

 

We're not really too worried about the deadline. It's just there to get people going a bit.

Oh... I misread the deadline... I thought it said today. Don’t mind me, I am the big dumb. 

[Sturgeon]

12 minutes ago, Lord_James said:

Oh... I misread the deadline... I thought it said today. Don’t mind me, I am the big dumb. 

 

Original deadline was a highly provisional June 10 IIRC. It's now July 10th, only slightly less provisional.

[Sturgeon]

All the features I had originally planned for Comanche are now done! Hooray!

 

[Sturgeon]

Basic parameters are done!

 

Table of basic statistics:

Parameter	Value
Mass, combat	124,000 lbs (62.0 tons)
Length, combat (transport)	25.6 ft (31.7 ft)
Width, combat (transport)	12.1 ft (12.0 ft)
Height, combat (transport)	8.8 ft (8.3 ft)
Ground Pressure, zero penetration	1,795 psf
Estimated Speed	50 mph
Estimated range	525 mi
Crew, number (roles)	4 (Commander, Gunner, Loader, Driver)
Main armament, caliber (ammo count ready/stowed)	40 (33 in turret bustle rack, 7 in ready rack)
Secondary armament, caliber (ammo count ready/stowed)	1,200 rds .50 caliber, 10,000 rds .30 caliber, 3,000 rds .40 cal ammunition

 

[Sturgeon]

[Sturgeon]

[A. T. Mahan]

I lost my NX license and ran into some other technical issues, so I doubt I'll be able to finish the modelling for my submission. I'll explain what the submission was below, though, for your consideration. If some "fluff" or in-universe explanation is desired as to how this was feasible, one can be provided. I also have as a prototype the "B" hull with the newer NERA-optimized frontal geometry with the legacy "A" turret. Please feel free to ask any questions you may have.

 

Believing that the fundamentals of the "T-52" design from the Californian heavy tank competition were sound, I sought to rework it to incorporate the feedback that was given. The idea was to continue maturing the design through successive iterations until it would either A) win something or B) some crucial flaw be found that required restarting. To that end, there were two major areas of work. First, the hull shared the 68-degree glacis of a T-72 family tank. While we had previously made it work as a NERA array, it was kind of dodgy against the threats presented by the Californian RFP without heavy use of our Kontakt-1 knockoff. As the screenshots I posted showed, I had reprofiled the front of the vehicle to be more Abrams-ey, because the M1 family is a perfectly good NATO Box Tank and I like the looks. This provided a very large NERA array space, which would have been able to exceed the protection requirements handily. 

 

Next, I undertook to revise the turret design. My goal was to produce something much more in line with the Object 187/welded T-90 turret, although the turret had a more pronounced bustle, as in the "T-52". In broad terms, the layout of the turret was to be similar to the previous "T-52" turret design -- commander to the right of the gun, gunner to the left. The armor packages were substantially pushed inwards, removing the front overhang that caused the driver issues when attempting to enter and exit the vehicle while retaining the quite substantial level of protection and protection arc of that previous turret. The armor package composition was to be moderately revised, as there were gaps in it that required fixing, but that would have been relatively quick to resolve had not I lost access to the script that had been written to optimize the armor packages. I would like to reiterate that the previous turret frontal armor package design was capable of withstanding 43/59" RHAe tandem charges and 31" RHAe kinetic penetrators before the inclusion of the ERA package. It also had quite satisfactory turret side armor. The reduced turret overall size would also have shaved several tons off of the overall weight, as the protected volume would have been reduced from the previous great excess. A new gunner's doghouse sight would have been designed, with proper two-axis stabilization and provision for the laser rangefinder, as well as a stadiametric auxiliary rangefinder. Ammunition was to have been a derivative of the 125mm combustible-case APFSDS, HEAT-FS, and HE-FS projectiles in a fixed steel case cartridge. Performance would have been satisfactory based on preliminary results, and I may finish working that out because I don't need NX for it. 

 

Mobility was to be moderately reduced from the original 1,562 hp VDS-2240 design due to the lack of FADEC engine controls and thereby reduced specific power output, but the available 1,200hp turbosupercharged diesel V12 in an approximately 50-ton tank is quite solid, and the powerpack offered substantial room for growth in automotive performance. Studies were underway to determine the feasibility of a gas turbine, but I doubt such a power unit would be truly viable in this timeline until perhaps 2270.  The track system was to be the same T158 derivative. 

 

As a note, much of the advanced computer equipment was to be removed, or replaced with much more basic electrical or electromechanical systems, as possible. 

[Sturgeon]

10 hours ago, A. T. Mahan said:

I would like to reiterate that the previous turret frontal armor package design was capable of withstanding 43/59" RHAe tandem charges and 31" RHAe kinetic penetrators before the inclusion of the ERA package. It also had quite satisfactory turret side armor.

 

I'm a little confused by this. Could you show your math? You're describing a tank that is 12t lighter than Comanche with almost triple the armor protection.

[A. T. Mahan]

5 hours ago, Sturgeon said:

 

I'm a little confused by this. Could you show your math? You're describing a tank that is 12t lighter than Comanche with almost triple the armor protection.

 

This is based on the math for the previous competition, and those numbers were directly taken from that report and should be viewed in that context. I have not recalculated it with the current coefficients yet because I've been busy, although I suspect it will not lose a huge amount of protection. I will try to recalculate it tonight. The various members of the California team and I spent a lot of time and effort working up the previous armor package concept, and it seems to work extremely well. The vehicle also has a relatively small protected volume. The weight analysis comes from the volume of modeled components in NX, so I believe it to be quite robust. 

[Toxn]

52 minutes ago, A. T. Mahan said:

 

This is based on the math for the previous competition, and those numbers were directly taken from that report and should be viewed in that context. I have not recalculated it with the current coefficients yet because I've been busy, although I suspect it will not lose a huge amount of protection. I will try to recalculate it tonight. The various members of the California team and I spent a lot of time and effort working up the previous armor package concept, and it seems to work extremely well. The vehicle also has a relatively small protected volume. The weight analysis comes from the volume of modeled components in NX, so I believe it to be quite robust. 

What's the weight of the bare hull and turret plus the armour components? 

[N-L-M]

As I recall that armor array left much to be desired in terms of coverage, as the cassettes weren't properly overlapped.

[Sturgeon]

26 minutes ago, N-L-M said:

As I recall that armor array left much to be desired in terms of coverage, as the cassettes weren't properly overlapped.

 

That's what I suspected. I would expect his tank to be lighter than Comanche for all the usual reasons, but not that much lighter with 2-3 times the armor!