A. T. Mahan

Oooh please show your work. I think I still have a copy of NavCAD 2014 lying around, or I could just teach myself how to use ANSYS.
 
I don't care if it's important or not, when you're citing things that are not documented in builder's trials that you're claiming you've seen calculations of, fucking show your work. 
 
Also, fuck you if you think CFD was viable before like 1978-1979. You cannot model to any useful degree of accuracy how a ship moves through water without using pretty hefty computers, and it's still not as accurate as well done model testing because there's so much turbulence at the stern and the scale is so large. If there's data on that, it's from builder's trials, acceptance trials, or model test data, and the USN was the only organization in the world with a large enough properly instrumented controlled model basin to do that sort of testing until the '60s or '70s. The David Taylor Model Basin was hands-down one of the most critical pieces of infrastructure, and contributed to the success of the US Navy ship design more than any other single facility. 
 
Now, on to your more recent comments:
 
Length to beam ratio matters more than thrust to weight, and the Iowa has better of both because it's not bluff and stubby. They also have a finer prismatic coefficient
 
The 35.2 for six hours was in open ocean in the Pacific, with IIRC reasonably cold water -- ships are faster in colder water because it's marginally denser and you don't melt things quite as quickly. 
 
As to why Yamato would run, for the same reason Bismarck would -- because it's asinine to go on a todesritt into the waiting lap of a superior force. Knowing the IJN, though, they'd do it and get shredded because all the Iowa has to do is sorta turn around and lead them on until they run out of gas.
 
The Yamato supposedly had some IR equipment of some sort, but even the best IR night vision equipment of 1945 Japan would be laughably useless compared to a functional and well-designed fire control radar.
 
Honestly, I'm kind-of dissappointed in you. You're failing to mention the issues the Iowas had as a result of their extreme fineness forward, namely being quite wet forward of the B turret in rough seas, or that the bulbous bow wasn't as refined as that on the Yamatos, or the pile of other minor flaws in the design. 
 
Oh wait, that'd require you to know what you're talking about, and have some understanding of naval architecture. 
 
Overall, 2/10 the German naval architect who put a twin 6" mount on the bow of an already-front-heavy destroyer was better informed than you and he designed a ship that would sink itself in the intended operating environment

Just to clarify, this is what I edited my initial post to add:
 
1. They're inferior to a degree that is only very slightly outside the tolerances for the thickness of battleship armor. It's immaterial.
2. You still have to hit the enemy ship, and the mediocrity of the fire control system on Yamato precludes that.
3. Your statement on speed in a gun duel is categorically and demonstrably false, and has been known to be so since 19-0-fucking-5. The IJN won the battles of Yellow Sea and Tsushima Strait because of their fleet's superior speed and maneuverability. 
4. The Iowa class' gun mounts reload faster -- see the middle of the second paragraph above for more details. 
5. I don't follow your point, the 5"/38 is a fine DP gun. The 5"/54 that replaced it was better, but the /38 is a great gun and it gets the job done. Heavy secondary low angle armament went out of style with Dreadnought.
6. I'm not sure where you get inefficient engines and inferior electronics from the Iowas. Their powerplant was perfectly fine and extremely reliable, and met specifications, and the electronics fit was in every way superior to that of the Yamato class.
7. Battleships do as they're told. 
8. The Yamato has inferior firepower due to the slower rate of fire. 
9. The Yamato most likely does not win because the Iowa-class would dictate the terms of the engagement, and could simply disengage at will and return in more favorable circumstances, like at night when the Japanese couldn't see or reliably engage at long ranges. 

Tsushima Strait was in 1905. I think you're conflating it with Surigao Strait. There's a big fucking difference, as I outlined in an edit to my initial post in this thread. To summarize, the IJN beat the shit out of the Imperial Russian Navy because their ships were a knot faster, slightly more maneuverable, and had a gun armament biased towards heavy guns. The same thing also happened at the Battle of the Yellow Sea the year before. 
 
Mechanical accuracy means dick all if you can't point the gun in the right direction because the FCS is primitive and incapable of working when you're turning.
 
Spotter aircraft are going to get killed either by 5"/38 fire if it's close enough to give meaningful corrections, or by fighter cover, or by the Curtis SC Seahawks on the Iowa. 
 
Yamato was capable of 27 knots, period. I don't have access to the data anymore (it's probably in the SNAME or RINA journal, or at the DTMB), but I saw some hull testing on the design that they did after the war at the David Taylor Model Basin and it was kinda meh -- it's a pretty efficient hull design with a good bulbous bow, but the Iowa hull form is better suited to high speed, and the powerplant is 62,000hp more powerful than that of the Yamatos. It turns out, when you design a ship that's bluffer, 25,000 tons heavier, and less powerful, it's like five knots slower than a ship with a crazy long L:B and a super fine entry. The Iowas were designed from the get-go to be insanely fast, and they accomplished that handily.
 
Oh, and for the sake of argument, if we assume the Iowas could only sustain 30kts (which, again, is not accurate), they were still 2.5-3 knots faster than the Yamatos, which is double or treble the speed advantage that Togo had over Rozhestvensky at Tsushima. 

Tsushima Strait was in 1905. I think you're conflating it with Surigao Strait. There's a big fucking difference, as I outlined in an edit to my initial post in this thread. To summarize, the IJN beat the shit out of the Imperial Russian Navy because their ships were a knot faster, slightly more maneuverable, and had a gun armament biased towards heavy guns. The same thing also happened at the Battle of the Yellow Sea the year before. 
 
Mechanical accuracy means dick all if you can't point the gun in the right direction because the FCS is primitive and incapable of working when you're turning.
 
Spotter aircraft are going to get killed either by 5"/38 fire if it's close enough to give meaningful corrections, or by fighter cover, or by the Curtis SC Seahawks on the Iowa. 
 
Yamato was capable of 27 knots, period. I don't have access to the data anymore (it's probably in the SNAME or RINA journal, or at the DTMB), but I saw some hull testing on the design that they did after the war at the David Taylor Model Basin and it was kinda meh -- it's a pretty efficient hull design with a good bulbous bow, but the Iowa hull form is better suited to high speed, and the powerplant is 62,000hp more powerful than that of the Yamatos. It turns out, when you design a ship that's bluffer, 25,000 tons heavier, and less powerful, it's like five knots slower than a ship with a crazy long L:B and a super fine entry. The Iowas were designed from the get-go to be insanely fast, and they accomplished that handily.
 
Oh, and for the sake of argument, if we assume the Iowas could only sustain 30kts (which, again, is not accurate), they were still 2.5-3 knots faster than the Yamatos, which is double or treble the speed advantage that Togo had over Rozhestvensky at Tsushima. 

@Peasant As Tsushima Strait showed, even a handful of knots speed advantage can provide a decisive advantage. The Iowa class might sacrifice some protection, but in exchange they gain between five and seven knots on the Yamatos. This would allow them to dictate the conditions of the engagement, and as seen at Tsushima (And also at Yellow Sea but I digress), a force with even a 1-3 knot advantage could and would dictate the terms of engagement. 
 
Additionally, the 16"/50 Mark 7 gun with 16" AP shell Mark 8 is so close in performance to the Japanese 18.1" in armor penetration that the difference is immaterial -- it's within +/- 0.75" either way, which is getting awfully close to the tolerancing for the armor. The mounts for the Mark 7 gun were also significantly faster in elevation, 12 degrees/sec vs 8, increasing the rate of fire by reducing the depression to loading/elevation to firing solution time. The Iowas also depressed the gun to the loading angle during run-out, further improving the rate of fire. Their turrets were also twice as fast in train, 4 degrees/second vs 2 degrees/second for the Yamato. This allows tracking at greater ranges and high speeds, especially during the vessel's own maneuvers. I don't really want to do the math to figure out the maneuvers required to invalidate a fire control solution for the Yamato based on train rate, but it's almost certainly not relevant outside maybe 5,000yd in antiparallel courses, but during heavy maneuvering it would be invaluable. 
 
The Iowa class fire control system was fundamentally more advanced than that of the Yamato, and I'm not sure how you arrived at the position that a system requiring manual data transfer and manual tracking of the calculated fire control solution is superior to a system that does not provide those opportunities for human error. Furthermore, the Japanese fire control radars (principally the Type 22 Mod 4) were nowhere near as capable as the Mark 13, nor did the fire control system incorporate a stable vertical, which is a significant problem in a ship that will be expected to maintain a fire control system during maneuver. 
 
Having written that before your most recent post, I'll include a TL;DR:
 
1. They're inferior to a degree that is only very slightly outside the tolerances for the thickness of battleship armor. It's immaterial.
2. You still have to hit the enemy ship, and the mediocrity of the fire control system on Yamato precludes that.
3. Your statement on speed in a gun duel is categorically and demonstrably false, and has been known to be so since 19-0-fucking-5. The IJN won the battles of Yellow Sea and Tsushima Strait because of their fleet's superior speed and maneuverability. 
4. The Iowa class' gun mounts reload faster -- see the middle of the second paragraph above for more details. 
5. I don't follow your point, the 5"/38 is a fine DP gun. The 5"/54 that replaced it was better, but the /38 is a great gun and it gets the job done. Heavy secondary low angle armament went out of style with Dreadnought.
6. I'm not sure where you get inefficient engines and inferior electronics from the Iowas. Their powerplant was perfectly fine and extremely reliable, and met specifications, and the electronics fit was in every way superior to that of the Yamato class.
7. Battleships do as they're told. 
8. The Yamato has inferior firepower due to the slower rate of fire. 
9. The Yamato most likely does not win because the Iowa-class would dictate the terms of the engagement, and could simply disengage at will and return in more favorable circumstances, like at night.

@Peasant As Tsushima Strait showed, even a handful of knots speed advantage can provide a decisive advantage. The Iowa class might sacrifice some protection, but in exchange they gain between five and seven knots on the Yamatos. This would allow them to dictate the conditions of the engagement, and as seen at Tsushima (And also at Yellow Sea but I digress), a force with even a 1-3 knot advantage could and would dictate the terms of engagement. 
 
Additionally, the 16"/50 Mark 7 gun with 16" AP shell Mark 8 is so close in performance to the Japanese 18.1" in armor penetration that the difference is immaterial -- it's within +/- 0.75" either way, which is getting awfully close to the tolerancing for the armor. The mounts for the Mark 7 gun were also significantly faster in elevation, 12 degrees/sec vs 8, increasing the rate of fire by reducing the depression to loading/elevation to firing solution time. The Iowas also depressed the gun to the loading angle during run-out, further improving the rate of fire. Their turrets were also twice as fast in train, 4 degrees/second vs 2 degrees/second for the Yamato. This allows tracking at greater ranges and high speeds, especially during the vessel's own maneuvers. I don't really want to do the math to figure out the maneuvers required to invalidate a fire control solution for the Yamato based on train rate, but it's almost certainly not relevant outside maybe 5,000yd in antiparallel courses, but during heavy maneuvering it would be invaluable. 
 
The Iowa class fire control system was fundamentally more advanced than that of the Yamato, and I'm not sure how you arrived at the position that a system requiring manual data transfer and manual tracking of the calculated fire control solution is superior to a system that does not provide those opportunities for human error. Furthermore, the Japanese fire control radars (principally the Type 22 Mod 4) were nowhere near as capable as the Mark 13, nor did the fire control system incorporate a stable vertical, which is a significant problem in a ship that will be expected to maintain a fire control system during maneuver. 
 
Having written that before your most recent post, I'll include a TL;DR:
 
1. They're inferior to a degree that is only very slightly outside the tolerances for the thickness of battleship armor. It's immaterial.
2. You still have to hit the enemy ship, and the mediocrity of the fire control system on Yamato precludes that.
3. Your statement on speed in a gun duel is categorically and demonstrably false, and has been known to be so since 19-0-fucking-5. The IJN won the battles of Yellow Sea and Tsushima Strait because of their fleet's superior speed and maneuverability. 
4. The Iowa class' gun mounts reload faster -- see the middle of the second paragraph above for more details. 
5. I don't follow your point, the 5"/38 is a fine DP gun. The 5"/54 that replaced it was better, but the /38 is a great gun and it gets the job done. Heavy secondary low angle armament went out of style with Dreadnought.
6. I'm not sure where you get inefficient engines and inferior electronics from the Iowas. Their powerplant was perfectly fine and extremely reliable, and met specifications, and the electronics fit was in every way superior to that of the Yamato class.
7. Battleships do as they're told. 
8. The Yamato has inferior firepower due to the slower rate of fire. 
9. The Yamato most likely does not win because the Iowa-class would dictate the terms of the engagement, and could simply disengage at will and return in more favorable circumstances, like at night.

@Peasant As Tsushima Strait showed, even a handful of knots speed advantage can provide a decisive advantage. The Iowa class might sacrifice some protection, but in exchange they gain between five and seven knots on the Yamatos. This would allow them to dictate the conditions of the engagement, and as seen at Tsushima (And also at Yellow Sea but I digress), a force with even a 1-3 knot advantage could and would dictate the terms of engagement. 
 
Additionally, the 16"/50 Mark 7 gun with 16" AP shell Mark 8 is so close in performance to the Japanese 18.1" in armor penetration that the difference is immaterial -- it's within +/- 0.75" either way, which is getting awfully close to the tolerancing for the armor. The mounts for the Mark 7 gun were also significantly faster in elevation, 12 degrees/sec vs 8, increasing the rate of fire by reducing the depression to loading/elevation to firing solution time. The Iowas also depressed the gun to the loading angle during run-out, further improving the rate of fire. Their turrets were also twice as fast in train, 4 degrees/second vs 2 degrees/second for the Yamato. This allows tracking at greater ranges and high speeds, especially during the vessel's own maneuvers. I don't really want to do the math to figure out the maneuvers required to invalidate a fire control solution for the Yamato based on train rate, but it's almost certainly not relevant outside maybe 5,000yd in antiparallel courses, but during heavy maneuvering it would be invaluable. 
 
The Iowa class fire control system was fundamentally more advanced than that of the Yamato, and I'm not sure how you arrived at the position that a system requiring manual data transfer and manual tracking of the calculated fire control solution is superior to a system that does not provide those opportunities for human error. Furthermore, the Japanese fire control radars (principally the Type 22 Mod 4) were nowhere near as capable as the Mark 13, nor did the fire control system incorporate a stable vertical, which is a significant problem in a ship that will be expected to maintain a fire control system during maneuver. 
 
Having written that before your most recent post, I'll include a TL;DR:
 
1. They're inferior to a degree that is only very slightly outside the tolerances for the thickness of battleship armor. It's immaterial.
2. You still have to hit the enemy ship, and the mediocrity of the fire control system on Yamato precludes that.
3. Your statement on speed in a gun duel is categorically and demonstrably false, and has been known to be so since 19-0-fucking-5. The IJN won the battles of Yellow Sea and Tsushima Strait because of their fleet's superior speed and maneuverability. 
4. The Iowa class' gun mounts reload faster -- see the middle of the second paragraph above for more details. 
5. I don't follow your point, the 5"/38 is a fine DP gun. The 5"/54 that replaced it was better, but the /38 is a great gun and it gets the job done. Heavy secondary low angle armament went out of style with Dreadnought.
6. I'm not sure where you get inefficient engines and inferior electronics from the Iowas. Their powerplant was perfectly fine and extremely reliable, and met specifications, and the electronics fit was in every way superior to that of the Yamato class.
7. Battleships do as they're told. 
8. The Yamato has inferior firepower due to the slower rate of fire. 
9. The Yamato most likely does not win because the Iowa-class would dictate the terms of the engagement, and could simply disengage at will and return in more favorable circumstances, like at night.

So far i picked my "Top 3" lists of designs for a 45 t and for 25 t tanks, suggested what submissions should be dropped out of competition. Because of time zone differences and all this "life" thing, it may take a little more for judges to finalize things. But we are almost at a finishing line.

The Judges are now reviewing the entries. 

Flavor text: 
 
Excerpts from Snapshots: The Combat Record of the Medium Tank M4 As Told by The Crews That Fought Them, 2289, Renton University Press:
 
MG David Mcneil, CRA (Ret). Chief of CRA Armored Force from 2278 to 2282, MG Mcneil was the only Chief of the Armored Force to have begun his military career as an enlisted soldier. He also was a member of the 1st Sqdn (Tank), 1st Armored Brigade’s “First Class”, the first tank unit to be transitioned to the Medium Tank M4. Known for his highly aggressive leadership style and personal bravery, Mcneil has the dubious distinction of having bailed out of a Medium M4 from every hatch and every crew position. He has 38.875 tank kills and a further 47 probable kills, and has received eight Purple Heart medals. A renowned polymath, Mcneil holds advanced degrees in mechanical engineering and history, and currently splits his time between teaching military science at the Cascadian Military Academy and consulting with several defense contractors.
 
On first encountering the Medium M4:
Up until that point, we had been using the Medium M3, a fairly serviceable, if dated design by the late ‘30s. At that point, I was a fresh-faced nineteen year old private first-class, and while we knew our M3s weren’t quite the firebreathing impenetrable powerhouses that some of the more sensational papers made them out to be, we were damn proud of them and we thought they were pretty hot stuff. I remember the day that we were first introduced to the Medium M4. Our Squadron was loaded into a convoy of deuce-and-a-halfs and we were driven to the Renton Locomotive plant. Once we got there and had been shepherded to a set of bleachers outside this big field, our CO, Mike Anderson, a man who I then hated but would come to respect more than anyone except perhaps God and my mother, stood in front of us, and explained why we were there -- the Government had decided we were to get a new tank, they’d bought one, and they had chosen us to be the lab-rats for the field trials and IOC. He then called us to attention, turned on his heel, and waved to a guy by the corner of a nearby building, and we heard it for the first time. We all knew what a tank starting up sounded like -- you had the whine of the solenoid, the coughing and then roar of the engine as it spun and caught, and then a rumble as it settled down to idle. This was different -- all we heard was a quiet whine, which built to a sort of whistle. Of course, we’d all heard about jet engines, and seen video of the old pre-war Abrams, and some of us even read Aviation Week and knew that PacAero was working on turboprop and turbojet aircraft, but we figured that a tank turbine was a technical impossibility in the late 2230s.
 
The first thing we saw was the gun, which is one of the better ways to spot an M4 Medium. The damn thing is so long that it’s hard not to miss it, but we saw this gigantic barrel coming around the corner and one of my very good friends, Tony Anglio, whispered to me something like “This has to be some kind of joke, that gun’s bigger than our friggin tank!”. Then, the hull just sort-of floated into view. The double-acting torsion bars and massive shock absorbers on the M4 gave it a very distinctly floaty ride, since they were designed for a substantially heavier vehicle than the already-heavy M4. The thing that really struck all of us, I think, was how quiet the damn thing was, despite its large size. That said, the M4 was just a mean looking bastard. The M3 Medium was almost cute in its very traditional construction, and well-proportioned lines, while the M4 looked strange in comparison. We wouldn’t find out until later exactly why it had all the tiles and the fairly flat armor, at the time we figured it was steel, and a lot of it.
 
The M4 was always full of surprises. Once we saw it and got used to the sound, we figured, well, okay, it’s going to be pretty slow -- it’s got all that thick armor and that great big gun, and it’s fairly small. As if on cue, when it got right in front of the bleachers, the driver hit the gas and the damn thing took off! We would come to appreciate the amount of time and effort the Renton boys had put into the vehicle, and the lengths they had taken to finally give Cascadian tankers a technological edge over our Californian enemies.
 
On actually fighting the M4 Medium
 
The thing to keep in mind about the M4 -- and I mean the M4, not the M4A1 or A2, because each of those was almost a different tank in how heavily they upgraded them -- is that even for all its advancements, it was still a product of the era. Yes, it had a very advanced gun-laying system and two-axis stabilization, but they were fairly slow, and a lot of the better gunners got very adept at using the reticle to range the target. The automatic rangefinder still took a good four seconds of steadily tracking a target with an unbroken sight picture, not an easy feat in combat, and the mechanism really wasn’t technically mature, but it worked enough of the time to be a suitable stand-in for the laser rangefinders that replaced it. Oh, and the damn thing would stop working whenever the Contact explosive reactive armor tiles near the rangefinder blisters went off -- half the time we either took them off or replaced them with a chunk of solid steel, just so that we didn’t have to recalibrate the rangefinder. They never really fixed that, either.
 
At first, the M4 had hands-down the best armor in the world -- unsurprising, since it was more or less an unabashed copy of the HAP-1 package off the Prewar M1A1HA Abrams. It was easy to get lulled into a false sense of security by the ERA and the composite armor, and forget that the thickest the hull got was only three inches. It was quite common for the detonation of the ERA tiles to dent and bend the ¾” outer shell of the tank, especially the RAT tiles on the bow -- when they went off, it was something like 16 pounds of Composition B throwing a 12-pound steel plate into the hull.
 
On the Battle of Yreka, the combat debut of the M4 Medium
 
The gun and mobility on the M4 were exemplary. When we first hit the battlefield it gave those Calif[ornian]s a shock, let me tell you. I remember the first combat action we took. We were dug in on a ridgeline, had a line of sight out, damn must have been four kilometers or more. We’d just had our breakfast and buttoned up when they hit us. That was the first time I’d been under the “VT” shells. Proximity fuse, you see. All the fun of tree bursts without the trees. Then they laid in smoke. So thick you couldn’t hardly see the end of the gun barrel out the periscope. Played hell with the automatic rangefinders, not that they worked much anyway. Somehow we made it work. With a battalion of Califoria’s finest coming at a company of Cascadian Regulars, there’s not much of a choice anyhow. We held fire on ell-tee’s orders until a thousand meters. Then the whole platoon let go in one volley. They must have thought the gates of hell opened on ‘em or something. They had us three-to-one, but our position, armor and gun made it closer to even money. All I remember is Charlie, the TC, his fire commands. ‘Gunner tank 800 meters front AP fire’ then ‘Identified on the way’ and then ‘gunner new target 750m front’ and so on like that. I was in my own little world, y’know? I think we got four or five that day. And I thought to myself, this is it, the perfect tank.
 
 
1. LCOL Mark Ishmael Karol Edward Anderson was killed in action in March, 2243 defending Klamath Falls. He was posthumously awarded the Washington Cross with Valor Device for his actions.
2. SSgt. Tony Anglio, CRA (Ret.) served with distinction against both Mormon and Californian forces from the mid-2230s into the 2250s. He retired in 2265 after 24 years of service, primarily in the Armored Force.
3. The M4A1 incorporated an improved engine, revised and upgraded armor packages, and a refined, 55-caliber gun. The M4A2, the “Digital Four” (earning crude nicknames like Fister and Shocker), incorporated a fully electronic fire control computer and a laser rangefinder, new stabilizers, even heavier armor, electro-optical sighting systems, a new gas turbine and transmission, thermal imagers, and a version of the pre-war Watervliet M256 120mm 44-caliber gun. The current M4A3 brings the tank to its fourth gun, the M360A1 120mm 52-caliber smoothbore, it’s third engine, sixth armor package, and incorporates an active protection system and greatly improved laser rangefinder.
4. B Coy, 1/1 Tanks dug in on the ridgeline between old CA route 263 and US I-5 about two miles north of Yreka, CA on the night of March 22, 2240. A Coy. was arrayed to the north, slightly further up I-5, and C Coy. and the Dragoon Battalion of 1st Tanks occupied Yreka itself, with B-1/1 and 2bn of the 4th (Olympia) Infantry Bde. preparing for an assault on Siskiyou County Airport the next morning. Shortly before the jump-off time, the Californian 1st Battalion, 3rd Guards Heavy Tank Regiment, of the elite 8th Guards Shock Air Force Parachute-Tank Division Kamala Harris (An homage to a semi-mythological early 21st century politician revered by the Californians) launched a spoiling attack consisting of eighty two Mark Six heavy tanks and fifty two half-track infantry carriers, supported by significant tube artillery. This represented ten percent of the Californian inventory of Mark Six heavy tanks at the time. In a battle that firmly established the fearsome reputation of both LCol. M.I.K.E. Anderson and the M4 Medium, as well as the extreme ideological indoctrination of the Communist Guards-divisions, B Coy, 1/1 Tanks blunted and stopped the Californian attack, then began a vicious counterattack that included LCol. Anderson’s tank being disabled by infantry attack whilst he lead a headlong pursuit of the retreating enemy, after which he is rumored to have fought off an element of the Communist forces with a pistol and saber.
5. MG Charles M. Dietz, CRA (Ret) was one of three crewman in Barely Legal (M4 S/N 10052, now preserved at the Cascadian Military Museum, Renton) who attained the rank of Major General (including MG McNeil and MG Dana R. Carter, CRA (Ret). The loader, Sergei I. Danilov, reached the rank of Colonel before his death at the hands of Deseret agents during his tenure as commander, 4th Armored Cavalry Bde. He was killed during a running gunbattle in the streets of Pocatello, Idaho Territory, in 2265. His assassination was a great loss, as he was working on writing an operational maneuver doctrine based on pre-war Soviet and American work.

Flavor text: 
 
Excerpts from Snapshots: The Combat Record of the Medium Tank M4 As Told by The Crews That Fought Them, 2289, Renton University Press:
 
MG David Mcneil, CRA (Ret). Chief of CRA Armored Force from 2278 to 2282, MG Mcneil was the only Chief of the Armored Force to have begun his military career as an enlisted soldier. He also was a member of the 1st Sqdn (Tank), 1st Armored Brigade’s “First Class”, the first tank unit to be transitioned to the Medium Tank M4. Known for his highly aggressive leadership style and personal bravery, Mcneil has the dubious distinction of having bailed out of a Medium M4 from every hatch and every crew position. He has 38.875 tank kills and a further 47 probable kills, and has received eight Purple Heart medals. A renowned polymath, Mcneil holds advanced degrees in mechanical engineering and history, and currently splits his time between teaching military science at the Cascadian Military Academy and consulting with several defense contractors.
 
On first encountering the Medium M4:
Up until that point, we had been using the Medium M3, a fairly serviceable, if dated design by the late ‘30s. At that point, I was a fresh-faced nineteen year old private first-class, and while we knew our M3s weren’t quite the firebreathing impenetrable powerhouses that some of the more sensational papers made them out to be, we were damn proud of them and we thought they were pretty hot stuff. I remember the day that we were first introduced to the Medium M4. Our Squadron was loaded into a convoy of deuce-and-a-halfs and we were driven to the Renton Locomotive plant. Once we got there and had been shepherded to a set of bleachers outside this big field, our CO, Mike Anderson, a man who I then hated but would come to respect more than anyone except perhaps God and my mother, stood in front of us, and explained why we were there -- the Government had decided we were to get a new tank, they’d bought one, and they had chosen us to be the lab-rats for the field trials and IOC. He then called us to attention, turned on his heel, and waved to a guy by the corner of a nearby building, and we heard it for the first time. We all knew what a tank starting up sounded like -- you had the whine of the solenoid, the coughing and then roar of the engine as it spun and caught, and then a rumble as it settled down to idle. This was different -- all we heard was a quiet whine, which built to a sort of whistle. Of course, we’d all heard about jet engines, and seen video of the old pre-war Abrams, and some of us even read Aviation Week and knew that PacAero was working on turboprop and turbojet aircraft, but we figured that a tank turbine was a technical impossibility in the late 2230s.
 
The first thing we saw was the gun, which is one of the better ways to spot an M4 Medium. The damn thing is so long that it’s hard not to miss it, but we saw this gigantic barrel coming around the corner and one of my very good friends, Tony Anglio, whispered to me something like “This has to be some kind of joke, that gun’s bigger than our friggin tank!”. Then, the hull just sort-of floated into view. The double-acting torsion bars and massive shock absorbers on the M4 gave it a very distinctly floaty ride, since they were designed for a substantially heavier vehicle than the already-heavy M4. The thing that really struck all of us, I think, was how quiet the damn thing was, despite its large size. That said, the M4 was just a mean looking bastard. The M3 Medium was almost cute in its very traditional construction, and well-proportioned lines, while the M4 looked strange in comparison. We wouldn’t find out until later exactly why it had all the tiles and the fairly flat armor, at the time we figured it was steel, and a lot of it.
 
The M4 was always full of surprises. Once we saw it and got used to the sound, we figured, well, okay, it’s going to be pretty slow -- it’s got all that thick armor and that great big gun, and it’s fairly small. As if on cue, when it got right in front of the bleachers, the driver hit the gas and the damn thing took off! We would come to appreciate the amount of time and effort the Renton boys had put into the vehicle, and the lengths they had taken to finally give Cascadian tankers a technological edge over our Californian enemies.
 
On actually fighting the M4 Medium
 
The thing to keep in mind about the M4 -- and I mean the M4, not the M4A1 or A2, because each of those was almost a different tank in how heavily they upgraded them -- is that even for all its advancements, it was still a product of the era. Yes, it had a very advanced gun-laying system and two-axis stabilization, but they were fairly slow, and a lot of the better gunners got very adept at using the reticle to range the target. The automatic rangefinder still took a good four seconds of steadily tracking a target with an unbroken sight picture, not an easy feat in combat, and the mechanism really wasn’t technically mature, but it worked enough of the time to be a suitable stand-in for the laser rangefinders that replaced it. Oh, and the damn thing would stop working whenever the Contact explosive reactive armor tiles near the rangefinder blisters went off -- half the time we either took them off or replaced them with a chunk of solid steel, just so that we didn’t have to recalibrate the rangefinder. They never really fixed that, either.
 
At first, the M4 had hands-down the best armor in the world -- unsurprising, since it was more or less an unabashed copy of the HAP-1 package off the Prewar M1A1HA Abrams. It was easy to get lulled into a false sense of security by the ERA and the composite armor, and forget that the thickest the hull got was only three inches. It was quite common for the detonation of the ERA tiles to dent and bend the ¾” outer shell of the tank, especially the RAT tiles on the bow -- when they went off, it was something like 16 pounds of Composition B throwing a 12-pound steel plate into the hull.
 
On the Battle of Yreka, the combat debut of the M4 Medium
 
The gun and mobility on the M4 were exemplary. When we first hit the battlefield it gave those Calif[ornian]s a shock, let me tell you. I remember the first combat action we took. We were dug in on a ridgeline, had a line of sight out, damn must have been four kilometers or more. We’d just had our breakfast and buttoned up when they hit us. That was the first time I’d been under the “VT” shells. Proximity fuse, you see. All the fun of tree bursts without the trees. Then they laid in smoke. So thick you couldn’t hardly see the end of the gun barrel out the periscope. Played hell with the automatic rangefinders, not that they worked much anyway. Somehow we made it work. With a battalion of Califoria’s finest coming at a company of Cascadian Regulars, there’s not much of a choice anyhow. We held fire on ell-tee’s orders until a thousand meters. Then the whole platoon let go in one volley. They must have thought the gates of hell opened on ‘em or something. They had us three-to-one, but our position, armor and gun made it closer to even money. All I remember is Charlie, the TC, his fire commands. ‘Gunner tank 800 meters front AP fire’ then ‘Identified on the way’ and then ‘gunner new target 750m front’ and so on like that. I was in my own little world, y’know? I think we got four or five that day. And I thought to myself, this is it, the perfect tank.
 
 
1. LCOL Mark Ishmael Karol Edward Anderson was killed in action in March, 2243 defending Klamath Falls. He was posthumously awarded the Washington Cross with Valor Device for his actions.
2. SSgt. Tony Anglio, CRA (Ret.) served with distinction against both Mormon and Californian forces from the mid-2230s into the 2250s. He retired in 2265 after 24 years of service, primarily in the Armored Force.
3. The M4A1 incorporated an improved engine, revised and upgraded armor packages, and a refined, 55-caliber gun. The M4A2, the “Digital Four” (earning crude nicknames like Fister and Shocker), incorporated a fully electronic fire control computer and a laser rangefinder, new stabilizers, even heavier armor, electro-optical sighting systems, a new gas turbine and transmission, thermal imagers, and a version of the pre-war Watervliet M256 120mm 44-caliber gun. The current M4A3 brings the tank to its fourth gun, the M360A1 120mm 52-caliber smoothbore, it’s third engine, sixth armor package, and incorporates an active protection system and greatly improved laser rangefinder.
4. B Coy, 1/1 Tanks dug in on the ridgeline between old CA route 263 and US I-5 about two miles north of Yreka, CA on the night of March 22, 2240. A Coy. was arrayed to the north, slightly further up I-5, and C Coy. and the Dragoon Battalion of 1st Tanks occupied Yreka itself, with B-1/1 and 2bn of the 4th (Olympia) Infantry Bde. preparing for an assault on Siskiyou County Airport the next morning. Shortly before the jump-off time, the Californian 1st Battalion, 3rd Guards Heavy Tank Regiment, of the elite 8th Guards Shock Air Force Parachute-Tank Division Kamala Harris (An homage to a semi-mythological early 21st century politician revered by the Californians) launched a spoiling attack consisting of eighty two Mark Six heavy tanks and fifty two half-track infantry carriers, supported by significant tube artillery. This represented ten percent of the Californian inventory of Mark Six heavy tanks at the time. In a battle that firmly established the fearsome reputation of both LCol. M.I.K.E. Anderson and the M4 Medium, as well as the extreme ideological indoctrination of the Communist Guards-divisions, B Coy, 1/1 Tanks blunted and stopped the Californian attack, then began a vicious counterattack that included LCol. Anderson’s tank being disabled by infantry attack whilst he lead a headlong pursuit of the retreating enemy, after which he is rumored to have fought off an element of the Communist forces with a pistol and saber.
5. MG Charles M. Dietz, CRA (Ret) was one of three crewman in Barely Legal (M4 S/N 10052, now preserved at the Cascadian Military Museum, Renton) who attained the rank of Major General (including MG McNeil and MG Dana R. Carter, CRA (Ret). The loader, Sergei I. Danilov, reached the rank of Colonel before his death at the hands of Deseret agents during his tenure as commander, 4th Armored Cavalry Bde. He was killed during a running gunbattle in the streets of Pocatello, Idaho Territory, in 2265. His assassination was a great loss, as he was working on writing an operational maneuver doctrine based on pre-war Soviet and American work.

120MM GUN TANK T44
Renton Shipbuilding and Locomotive Works
A Pacific Car and Foundry Company
 
The 120mm Gun Tank T44, designed primarily by the Renton Shipbuilding and Locomotive division of Pacific Car and Foundry, is a fully-tracked armored fighting vehicle armed with a 120mm smoothbore gun. Research and exploratory investigation determined that there were a number of designs and concepts with great potential to leverage and improve the combat effect of the vehicle. The most promising hull that PACAR-RSL located was the M47 Patton -- the combination of castings and weldments of high-quality steel was well within the production capabilities of our facility, and the vehicle weight of 90000lbs would be able to be reduced sufficiently to meet the required weight limit. Noting that the vehicle weight specified in the contract (90,000lb) does not specify whether it is the unloaded or loaded weight, the Program Manager determined that it specified the unloaded weight. In any event, PACAR-RSL has several proposed variants (and has produced prototypes of them) that meet varying weight goals.
 
Structure:
The original M47’s structure is highly dated. While PACAR-RSL has substantial experience with high-quality castings of the scale required, and while PACAR produced M26 Pershing 90mm gun medium tanks in 1944 and 1945 (and retains sufficient quantities of the technical data package to resume production of mildly improved versions of those tanks if the Government would so desire), castings are not compatible with the composite armor techniques that PACAR and our subcontractors have developed based on combat-proven prewar efforts. As a shipbuilding concern, PACAR-RSL possesses substantial experience producing high-quality weldments of extremely high grade steels, and many of our welders are certified to weld armor steels. This trained and capable workforce allowed our design team to rework the monocoque (armor-as-structure) hull and turret of the M47 to suit both the HAP-1 derived armor package and to lighten the vehicle. This resulted in an allowable armor weight of nearly 10,000lb for the hull, sufficient to utilize the HAP-1 armor on a recontoured lower frontal hull.
The hull itself is constructed of welded 1.0” to 1.5” (+/- 0.05”) high strength steel plate,
The turret is of a completely new, all-welded design heavily inspired by the pre-war Abrams design, as far as general shape is concerned.
 
Protection:
 
Central to our design is the incorporation of highly advanced composite armors to reduce the threat of shaped-charge warheads. Pre-war literature indicated that these antitank munitions were most concerning for designers of the so-called first and second generation of main battle tanks, due to their light weight and relatively high penetrative ability, and Cascadian control of the only large supplies of depleted uranium and tungsten in the region result in a greatly reduced threat from long-rod fin-stabilized discarding sabot kinetic penetrators. In cooperation with the Pacific Aero Products Company of Seattle, we have spent considerable time and effort developing ceramic and other composite armor technologies, and believe that we have managed to develop an armor package similar in concept to the BRL-1 and HAP-1 armor packages used on various models of early model pre-war M1 Abrams tanks. Our testing has determined that the armor package we have chosen for the vehicle is substantially lighter and more protective than rolled homogeneous steel or cast steel armor, although it is bulkier and substantially more expensive. The armor utilizes combinations of three types of Non-Explosive Reactive Armor (NERA) packages, the Type I array of three thin parallel sandwiches of 5083-H32/elastomer/5083-H32 mounted on large pre-compressed coil springs, the Type II array of layered ceramic/5083-H32/elastomer/5083-H32 sandwich plates mounted at an angle such that an incoming projectile from within 15 degrees of horizontal must penetrate a minimum of four panels, and the Type IIIA/B composite array. We utilize two different composite arrays. The Type IIIA, used on the turret face, consists of a layer of ceramic tiles, a fiberglass-reinforced polymer backer, a layer of elastomer, a layer of depleted uranium, a fiberglass-reinforced polymer backer, a layer of high hardness armor steel, and the hull structure. The Type IIIB, used on the turret sides and lower glacis plate, is the same as that on the turret face, except the depleted uranium is replaced with high hardness steel. This reduces protection against kinetic energy penetrators, but greatly reduces weight, as high hardness steel is 60% lighter than depleted uranium, and the protection is still very good.
 
We have been particularly focused on Carborundum (Silicon Carbide) as the ceramic used in the armor, although experiments have determined that Boron Carbide offers more protection, but is substantially more difficult to manufacture and work with. While large quantities of B4C exist at the Hanford Site in the form of neutron dampers and shielding, and control rods, they would require substantial effort to form into a usable armor material and at this time the yield rate on B4C tiles of the appropriate size is low to the point of total impracticality - at best, we have determined that current technology will produce no more than 5% of a given batch of tiles that meets QA/QC. We have therefore determined that the most weight and efficient armor scheme would be to more-or-less duplicate the HAP-1 armor construction, substituting Silicon Carbide for Boron Carbide where appropriate, and utilizing the supplies of depleted uranium available at the Hanford Site (estimated to be 2,380 tons, appropriate for approximately 750 vehicles based on current projections of 6000lb of DU per vehicle) would provide substantial kinetic protection at the cost of increased weight.
Our armor concept, admittedly very heavily inspired by that of the early M1 Abrams designs, provides significant protection for its weight, especially considering the smaller protected volume and reduced level of protection chosen. The turret faces are intended to provide protection equivalent to 20-25 inches of rolled homogeneous steel, but are some 70% lighter.
We would note that the Cascadian Government should seek to acquire access to greater supplies of uranium for use in this and other defence programs, and note that research indicates four thousand tons of dry-cask stored spent nuclear fuel each in the former Illinois, former Pennsylvania, and former South Carolina regions and between 3,000 and 4,000 tons each in California, former Alabama, Florida, New York, and Georgia regions. While most of these areas are over a thousand miles away, if Cascadia can secure access to these supplies, they represent approximately 32,500 tons of highly enriched uranium, which would be invaluable for reprocessing into depleted uranium for tank armors, or Special Materials for use in other programs. PACAR-RSL has been making inquiries through traditional trade channels as to the feasibility of cross-country transportation of these materials, but government support would aid the endeavour greatly.
It is worth mentioning that this armor design package more-or-less requires the production of a gaseous-diffusion uranium enrichment cascade and the production of weapons-grade uranium. This could be expected to produce 16.9 tons of U-235, enough for over two thousand 25-kiloton nuclear devices.
Further protection comes from the incorporation of Contact and Rat, explosive reactive armours derived from the Soviet Kontakt-family tiles. Similar except for size and shape, these require no outside initiation, being a box with two steel plates sandwiching a piece of explosive. Contact is used primarily on the turret face, bow, hull, and turret sides, while Rat, derived from the curved tile of the pre-war US Army M19 ARAT tile, is used only on the hull and turret sides as an up-armor kit. Each Contact tile is 12” wide, 6” tall, and weighs 12.5lb. Each Rat tile weighs approximately 40lb, is 20” tall, 15” wide, and mounted on a hinged bracket that allows them to be angled vertical, or angled about 15 degrees down. This reduces the danger to supporting infantry posed by the tile’s detonation. The 238 Contact and 47 Rat tiles able to be mounted on the vehicle only add a maximum of 4,900lb including mounting hardware while providing greatly increased protection.

Contact explosive reactive armor tile (12"x6", 12.5lb)

Rat explosive reactive armor tile (15"x20", 40lb)
 
The armor layout is as follows:
Turret
Turret face:
0.75” HHS face armor, Type I array, Type II array, Type IIIA array, 1” RHA structure
16" RHAe kinetic, 30" RHAe chemical
14 tiles per side of Contact, 28 total
Contact tiles provide 14" RHAe against single-stage HEAT threats, ~4" RHAe against full-caliber kinetic threats. 
Turret side:
0.75” HHS face, Type I array, Type II array, Type IIIB array, 0.75” RHA structure
12" RHAe kinetic, 27" RHAe chemical
11 tiles Contact and 7 RAT tiles per side, 22 Contact and 14 RAT tiles.
RAT tiles provide 18" RHAe against single stage HEAT warheads, 20" RHAe against full-caliber kinetic threats, and decrease the efficacy of subcaliber kinetic threats by 15%. This is due to the greater thickness of steel in the tile. 
Turret rear:
2.25” HHS over 0.75” RHA
3.5" RHAe
Turret roof:
1.0” HHS
1.2" RHAe
28 Contact tiles
Hull
Upper glacis plate:
3” HHS plate sloped at 80 degrees from vertical (17” LOS)
20" RHAe line of sight
44 Contact tiles
Lower glacis plate:
0.75” HHS plate, Type I array, Type II array, Type IIIB array, 1” HHS hull
12.5" RHAe kinetic, 27.5" RHAe chemical
5 tiles Rat
Hull Side:
2.25” HHS over 0.75” RHA
3.5" RHAe
Up-armor side-skirts consisting of a Type I array
5" RHAe kinetic, 11" RHAe chemical
70 tiles Contact per side plus 28 tiles of RAT
Hull rear: 2.0” RHA
Hull bottom: 0.75” HHS
0.9" RHAe
Hull roof: 0.75” HHS
0.9" RHAe

 
Firepower:
Other work with the Pacific Aero Products Company focused on the development of improved ammunition designs. PACAR-RSL leveraged PAPC’s advanced aerodynamic analytical techniques to aid in the development of improved fin-stabilized smoothbore ammunition. Research on prewar technologies demonstrated a number of programs conducted by the prewar US Army that incorporated smoothbore guns, and industrial analysis has determined that a maximum chamber-pressure of 55,000psi is within current capabilities, and based on research trends in metallurgy, a chamber pressure of 75,000psi should be achievable within five years, and 100,000psi in ten years. While this will result in a lengthened gun compared to prewar designs (The M256 120mm gun was only a 44-caliber gun), a 50-caliber 120mm gun with a tube weight of not more than 2,900lb and an all-up weight of not more than 4,400lb is entirely viable.
We have developed a gun, the 120mm Gun T123E7, that produces a muzzle energy of 4,300 ft-ton with a 50lb armor-piercing capped, ballistic capped projectile (MV = 3,500ft/sec, 50lb shot M358). We estimate that this will drive a 22lb Hanfordite (U-238) penetrator at approximately 4,500ft/sec, giving the capability to defeat greater than 25” of rolled homogenous steel at 2,000 yards, and greatly simplifying the design of the ballistic computer. It uses a vertically sliding breechblock reverse-engineered at great length from surviving examples of the Watervliet Arsenal-produced M256 120mm gun. While the current metallurgy and QA/QC is not sufficient to produce breech blocks capable of the 135,000psi of M256, we believe that with advances in electronically controlled machining, it is feasible. We are planning an exploratory expedition to the Watervleit Arsenal area to gain what prewar technical data we can, particularly on the M256 and M360 guns.

Gun, Smoothbore, 120mm T123E7 (120x570R, L/60)
T123E7 is a 60-caliber 120-mm smoothbore gun with a vertically sliding breechblock, hydropneumatic recoil mechanism, and chrome-lined bore. It has a fume extractor to reduce the rate of propellant gas ingress into the turret, and a thermal sleeve to stabilize the temperature along the bore and reduce bore irregularities due to thermal expansion. It fires 120x570mm fixed ammunition using a cellulose-fiber combustible cartridge case with a metal base cap, reducing the weight of the cartridge case by some 30lb compared to a brass case (107lb for brass case M358 APC-T vs ~55lb for T494 APFSDS-T). Decreased AP projectile weight due to the usage of armor-piercing fin-stabilized discarding sabot ammunition further reduces the weight of the armor-piercing projectile by nearly half, from 50lb to 26lb.

120mm XM442 Armor-Piercing Fin-Stabilized Discarding Sabot, Tracer (22lb Oralloy penetrator, 4,400ft/s MV)
 
Additional projectiles, such as HEP-FS-T, HE-FRAG-FS-T and HEAT-FS-T are under development, as are training projectiles.

120mm M358E1 APCBC-FS-T (50lb projectile, 3,500ft/s MV)
 
The gun and mount are electrically driven in train and elevation via a geared drive and proportionally controlled motors derived from a mixture of naval fire control equipment and aircraft gun turrets. This had an added benefit of easing the development of an analog two-axis gun stabilization system. The fire control system is electromechanical and analog-electronic, and consists of four components: the T92D gunner’s articulated periscope, the T19 automatic stereoscopic rangefinder, the electrical gun drive, and the T14 gun computer. The gun computer is a miniaturized transistorized electromechanical and analog-electronic computer that incorporates ambient temperature, range as measured from the stereoscopic rangefinder, and the average rate of traverse of the gun over the past one to three seconds to apply lead, cant and Coriolis correction, and superelevation, and align the gun to the sights. When the firing switch is depressed, a set of microswitches delays completion of the firing circuit until the sights are properly aligned, aiding in firing on the move or from a short halt. The gunner’s articulated periscope is a combination 1x-3x variable power unity sight and 3-20x magnified sight, with coated lenses, reticle illumination, and incorporating image intensifying night vision equipment. The image intensifying system is mounted at the end of the optical train, allowing the gunner to use the full magnification range even in reduced lighting conditions. The T19 rangefinder is mounted across the width of the turret and is a 108” base stereoscopic rangefinder equipped with an electro-optical automatic ranging mechanism.
 
Using the following equations, from Material Testing Procedure 3-2-702 (US Army Test and Evaluation Command, Common Engineering Test Procedure for Optical Rangefinders, 20 Apr. 1966, Aberdeen, Maryland), we calculate the T19 rangefinder has a mechanical accuracy of [x] meters. 


For a base length B of 2.769m, a range R1 of 2,000m
[math goes here]
 
The rangefinder can be used by the commander in the manual mode to either produce a more accurate ranging solution and in the event of automatic ranging mechanism failure. Both the commander and gunner can use the rangefinder, although as the fire control system is designed around and as-yet unproduced laser rangefinder, the primary control of automatic rangefinding is on the gunner's controls. The T14 gun computer can also accept manual input of range information via a dial, in 100-yard increments. The automatic mechanism is derived from Leika’s work in camera autofocus mechanisms, and is based on a small array of lead (II) sulfide photosensors similar to those used in early-model AIM-9 Sidewinder air-to-air missiles and a very simple electrical circuit. Early testing has determined that it can resolve ranges with a similar accuracy as a human operator in ⅓-½ the time, depending on the skill of the human operator. The turret and rangefinding system is also designed for-but-not-with a laser rangefinder, which would replace the optical rangefinder and improve gun depression from 12 degrees to 14 degrees. A laser rangefinder similar to the prewar AN/VVG-2 (Ruby, 694.3nm, 50mJ pulse, 125J maximum output) as used in the M60A3 would reduce the ranging time to 1.5 seconds and reduce the typical ranging error from several hundred yards to tens of yards. The ranging time is currently the largest component of the firing sequence, as the design of the T14 gun computer requires it to constantly update the firing solution for all inputs except range and lead, and lead correction is applied more-or-less instantaneously upon depression of the gunner's automatic ranging switch. 
The T123E7 120mm smoothbore gun is provided with 56 rounds of ammunition in a blow-out protected bustle rack and twenty-four rounds in supplementary ammunition racks to either side of the loader, a total of 80 rounds. There is a 7.62mm M240 machine gun mounted coaxially to the main gun, with 8,000 rounds of 7.62x51mm (2,000 ready). There is a 7.62mm M240 machine gun provided for the loader mounted in a race-ring mount around his hatch with 2,000 rounds of 7.62x51mm (200 ready) There is a .50 M2 machine gun provided for the commander on a ring mount around the commander’s cupola with 2,000 rounds of .50 ammunition (100 ready) Provision is made for the storage of the crew’s individual weapons and field equipment, including four 5.56mm rifles and ammunition.  
Mobility:
T44 uses a torsion-bar suspension, with six individually sprung road-wheels per track connected to double-acting bar-in-tube springs providing substantially improved suspension travel to the original single-acting suspension.
There are two powertrains currently proposed. The first, a prewar design Continental AVDS-1790-5B is a known quantity, an extremely reliable and widely used turbosupercharged diesel V-12 producing 810 horsepower at 2,400RPM. This, in combination with the CD-875-2 four-speed automatic transmission produces a maximum speed of 35 miles an hour on road, and the improved double-acting torsion bar suspension provides an increased rough-terrain speed of approximately 12 miles per hour, compared to nine miles an hour for the Medium Tank M4. This gives the vehicle a combat range of approximately 430 miles with 310 gallons of Diesel fuel.
The second powertrain is derived from prewar work on gas turbines. It is a simple, reliable gas turbine of 65” length and 25” diameter that, due to manufacturing limitations, only produces about 1,000 horsepower. Similar prewar designs produced approximately 1,500 horsepower in ground use and 1,800 horsepower in aviation use, but due to manufacturing limitations and for safety reasons, the turbine is limited to 1,200hp SHP emergency power for ten minutes, and 1,000 horsepower maximum. This drives a CD-1100-4F2 crossdrive automatic six-speed transmission (four forward, two reverse), resulting in a maximum road speed of 48 miles per hour and a rough-terrain speed of 22 miles per hour, although crew comfort is a significant concern and shock absorption is an issue at such speeds. This engine, with the associated APU, gives the vehicle a combat range of approximately 375 miles, although with greater speed than the AVDS-1790.
The strategic mobility of the T44 tank is provided by the vehicle’s high speed and substantial reliability. Rail transport of the T44 requires removing the side-skirts and side explosive reactive armor tiles, requiring one hour per vehicle plus a wrecker capable of lifting 1,300lb. Alternatively, the vehicle can be road-marched in combat condition. 
 
In summary, the T44 medium tank meets all of the required design specifications:
It is 90,000lb unloaded, and 128,000lb at combat weight.
The fenders fold up to ensure a 129” maximum width (otherwise 135” width)
The upper frontal plate is 3” thick sloped at 80 degrees from vertical, giving an effective line of sight thickness of 17”
The side armor is 3” thick
The power to weight ratio is at worst 16hp/ton (loaded, 810hp engine) and at best 19.6hp/ton
The tank has a crew of four: Driver, TC, gunner, and commander.
The primary armament, 120mm gun T123E7, is capable of firing both antiarmor and high explosive projectiles.
9ft 8” tall

 
120mm Gun Tank T44 specifications:
Empty weight: 94,000lb Operating empty weight: 109,250lb Combat weight: 128,000lb Height: 116" Width: 168.639 inches Length: 233.5" (hull), 415.5" overall, gun forward. Ground clearance: 21" at combat weight, less at OEW. Engine: Pseudo-Lycoming T53, 750lb/1,000shp APU: Two-stroke 25 horsepower Yamaha outboard powerhead Transmission: CD-1100-4F2. Four speeds forward, two reverse. Automatic crossdrive transmission. Engine and transmission are a powerpack.  Track: Modified T158 track, cut down to 23" wide.  Suspension: 74" long bar-in-tube double acting torsion bars, friction snubbers on the first two and last two pairs of road wheels each side (duals on the first road wheel), shock absorbers on the first, second, fifth, and sixth road wheels each side. Three return rollers each side. A total of 16" of compression and 8" of rebound at combat weight results in 24" of total suspension travel.  Fuel capacity: 325 gallons Range: ~150-200 miles  
Armor weight budget:

 
Weight budget

Hey! I'm working on a medium tank design right now -- I might have to hand draft it rather than doing it up in NX since I can't find a good model to work off of and I'm not going to try to design a tank in NX from scratch with my courseload right now, but it's going to be good.
 
 Here's a very rough draft, lacking graphics because I'm going to make those tomorrow:
 


The 120mm Gun Tank T44, designed primarily by the Renton Shipbuilding and Locomotive division of Pacific Car and Foundry, is a fully-tracked armored fighting vehicle armed with a 120mm smoothbore gun. Research and exploratory investigation determined that there were a number of designs and concepts with great potential to leverage and improve the combat effect of the vehicle. The most promising hull that PACAR-RSL located was the M47 Patton -- the combination of castings and weldments of high-quality steel was well within the production capabilities of our facility, and the vehicle weight of 93000lbs would be able to be reduced sufficiently to meet the required weight limit. Noting that the vehicle weight specified in the contract (90,000lb) does not specify whether it is the unloaded or loaded weight, the Program Manager determined that it specified the unloaded weight. In any event, PACAR-RSL has several proposed variants (and has produced prototypes of them) that meet varying weight goals.
 
Structure:
The original M47’s structure is highly dated. While PACAR-RSL has substantial experience with high-quality castings of the scale required, and while PACAR produced M26 Pershing 90mm gun medium tanks in 1944 and 1945 (and retains sufficient quantities of the technical data package to resume production of mildly improved versions of those tanks if the Government would so desire), castings are not compatible with the composite armor techniques that PACAR and our subcontractors have developed based on combat-proven prewar efforts. As a shipbuilding concern, PACAR-RSL possesses substantial experience producing high-quality weldments of extremely high grade steels, and many of our welders are certified to weld armor steels. This trained and capable workforce allowed our design team to rework the monocoque (armor-as-structure) hull and turret of the M47 to suit both the HAP-1 derived armor package and to lighten the vehicle. This resulted in an allowable armor weight of nearly 10,000lb for the hull, sufficient to utilize the HAP-1 armor on a recontoured lower frontal hull.
The hull itself is constructed of welded 1.0” to 1.5” (+/- 0.05”) high strength steel plate,
The turret is of a completely new, all-welded design heavily inspired by the pre-war Abrams design, as far as general shape is concerned.
 
Protection:
 
Central to our design is the incorporation of highly advanced composite armors to reduce the threat of shaped-charge warheads. Pre-war literature indicated that these antitank munitions were most concerning for designers of the so-called first and second generation of main battle tanks, due to their light weight and relatively high penetrative ability, and Cascadian control of the only large supplies of depleted uranium and tungsten in the region result in a greatly reduced threat from long-rod fin-stabilized discarding sabot kinetic penetrators. In cooperation with the Pacific Aero Products Company of Seattle, we have spent considerable time and effort developing ceramic and other composite armor technologies, and believe that we have managed to develop an armor package similar in concept, but less protective, than the BRL-1 armor used on early model pre-war M1 Abrams tanks. Our testing has determined that the armor package we have chosen for the vehicle is substantially lighter and more protective than rolled homogeneous steel or cast steel armor, although it is bulkier and substantially more expensive.
We have been particularly focused on Carborundum (Silicon Carbide) as the ceramic used in the armor, although experiments have determined that Boron Carbide offers more protection, but is substantially more difficult to manufacture and work with. While large quantities of B4C exist at the Hanford Site in the form of neutron dampers and shielding, and control rods, they would require substantial effort to form into a usable armor material and at this time the yield rate on B4C tiles of the appropriate size is low to the point of total impracticality - at best, we have determined that current technology will produce no more than 5% of a given batch of tiles that meets QA/QC. We have therefore determined that the most weight and efficient armor scheme would be to more-or-less duplicate the HAP-1 armor construction, substituting Silicon Carbide for Boron Carbide where appropriate, and utilizing the supplies of depleted uranium available at the Hanford Site (estimated to be 2,380 tons, appropriate for approximately 750 vehicles based on current projections of 6000lb of DU per vehicle) would provide substantial kinetic protection at the cost of increased weight.
Our armor concept, admittedly very heavily inspired by that of the early M1 Abrams designs, provides significant protection for its weight, especially considering the smaller protected volume and reduced level of protection chosen. The turret faces are intended to provide protection equivalent to 20-25 inches of rolled homogeneous steel, but are some 70% lighter.
We would note that the Cascadian Government should seek to acquire access to greater supplies of uranium for use in this and other defence programs, and note that research indicates four thousand tons of dry-cask stored spent nuclear fuel each in the former Illinois, former Pennsylvania, and former South Carolina regions and between 3,000 and 4,000 tons each in California, former Alabama, Florida, New York, and Georgia regions. While most of these areas are over a thousand miles away, if Cascadia can secure access to these supplies, they represent approximately 32,500 tons of highly enriched uranium, which would be invaluable for reprocessing into depleted uranium for tank armors, or Special Materials for use in other programs. PACAR-RSL has been making inquiries through traditional trade channels as to the feasibility of cross-country transportation of these materials, but government support would aid the endeavour greatly.
It is worth mentioning that this armor design package more-or-less requires the production of a gaseous-diffusion uranium enrichment cascade and the production of weapons-grade uranium. This could be expected to produce 16.9 tons of U-235, enough for over two thousand 25-kiloton nuclear devices.
Further protection comes from the incorporation of Contact, an explosive reactive armor derived from the Soviet Kontakt-5 tiles. These require no outside initiation, being a box with two steel plates sandwiching a piece of explosive, and the 150 tiles used on the vehicle only add 1,900lb including mounting hardware while providing greatly increased protection.
 
Firepower:
Other work with the Pacific Aero Products Company focused on the development of improved ammunition designs. PACAR-RSL leveraged PAPC’s advanced aerodynamic analytical techniques to aid in the development of improved fin-stabilized smoothbore ammunition. Research on prewar technologies demonstrated a number of programs conducted by the prewar US Army that incorporated smoothbore guns, and industrial analysis has determined that a maximum chamber-pressure of 55,000psi is within current capabilities, and based on research trends in metallurgy, a chamber pressure of 75,000psi should be achievable within five years, and 100,000psi in ten years. While this will result in a lengthened gun compared to prewar designs (The M256 120mm gun was only a 44-caliber gun), a 50-caliber 120mm gun with a tube weight of not more than 2,900lb and an all-up weight of not more than 4,400lb is entirely viable.
We have developed a gun, the 120mm Gun T123E7, that produces a muzzle energy of 4,300 ft-ton with a 50lb armor-piercing capped, ballistic capped projectile (MV = 3,500ft/sec, 50lb shot M358). We estimate that this will drive a 22lb Hanfordite (U-238) penetrator at approximately 4,500ft/sec, giving the capability to defeat greater than 25” of rolled homogenous steel at 2,000 yards, and greatly simplifying the design of the ballistic computer. It uses a vertically sliding breechblock reverse-engineered at great length from surviving examples of the Watervliet Arsenal-produced M256 120mm gun. While the current metallurgy and QA/QC is not sufficient to produce breech blocks capable of the 135,000psi of M256, we believe that with advances in electronically controlled machining, it is feasible. We are planning an exploratory expedition to the Watervleit Arsenal area to gain what prewar technical data we can, particularly on the M256 and M360 guns.
T123E7 is a 52-caliber 120-mm smoothbore gun with a vertically sliding breechblock, hydropneumatic recoil mechanism, and chrome-lined bore. It fires 120x570mm fixed ammunition using a cellulose-fiber combustible cartridge case with a metal base cap, reducing the weight of the cartridge case by some 30lb compared to a brass case (107lb for brass case M358 APC-T vs ~55lb for T494 APFSDS-T). Decreased AP projectile weight due to the usage of armor-piercing fin-stabilized discarding sabot ammunition further reduces the weight of the armor-piercing projectile by nearly half, from 50lb to 26lb.
Additional projectiles, such as HEP-FS-T, HE-FRAG-FT-T and HEAT-FS-T are under development, as are training projectiles.
The gun and mount are electrically driven in train and elevation via a geared drive and proportionally controlled motors derived from a mixture of naval fire control equipment and enlarged aircraft gun turrets. This has an added benefit of easing the development of an analog two-axis gun stabilization system. The fire control system is electromechanical and analog-electronic, and consists of [x] components: the gunner’s articulated periscope, the commander’s stereoscopic rangefinder, the electrical gun drive, and the gun computer. The gun computer is a miniaturized transistorized electromechanical/analog-electronic computer that incorporates ambient temperature, range as measured from the stereoscopic rangefinder, and the average rate of traverse of the gun over the past one to three seconds to apply lead, cant correction, and superelevation, and align the gun to the sights. When the firing switch is depressed, a set of microswitches waits to close the firing circuit until the sights are properly aligned, aiding in firing on the move or from a short halt. The gunner’s articulated periscope is a combination 1x-3x unity sight and 3-20x magnified sight, with coated lenses, reticle illumination, and compatibility with infra-red image intensifying night vision equipment. The rangefinder is mounted across the width of the turret.
There is a 7.62mm M240 machine gun mounted coaxially to the main gun, with 8,000 rounds of 7.62x51mm (2,000 ready).
There is a 7.62mm M240 machine gun provided for the loader mounted in a race-ring mount around his hatch with 2,000 rounds of 7.62x51mm (200 ready)
There is a .50 M2 machine gun provided for the commander on a ring mount around the commander’s cupola with 2,000 rounds of .50 ammunition (100 ready)
Provision is made for the storage of the crew’s individual weapons and field equipment, including four 5.56mm rifles and ammunition.
 
Mobility:
T44 uses a torsion-bar suspension, with six individually sprung road-wheels per track connected to double-acting bar-in-tube springs providing substantially improved suspension travel to the original single-acting suspension.
There are two powertrains currently proposed. The first, a prewar design Continental AVDS-1790-5B is a known quantity, an extremely reliable and widely used turbosupercharged diesel V-12 producing 810 horsepower at 2,400RPM. This, in combination with the CD-875-2 four-speed automatic transmission produces a maximum speed of 35 miles an hour on road, and the improved double-acting torsion bar suspension provides an increased rough-terrain speed of approximately 12 miles per hour, compared to nine miles an hour for the Medium Tank M4. This gives the vehicle a combat range of approximately 125 miles.
The second powertrain is derived from prewar work on gas turbines. It is a simple, reliable gas turbine of 65” length and 25” diameter that, due to manufacturing limitations, only produces about 1,000 horsepower. Similar prewar designs produced approximately 1,500 horsepower in ground use and 1,800 horsepower in aviation use, but due to manufacturing limitations and for safety reasons, the turbine is limited to 1,200hp SHP emergency power for ten minutes, and 1,000 horsepower maximum. This drives a CD-1250-1 crossdrive automatic five-speed transmission, resulting in a maximum road speed of 48 miles per hour and a rough-terrain speed of 22 miles per hour, although crew comfort is a significant concern and shock absorption is an issue at such speeds. This engine, with the associated APU, gives the vehicle a combat range of approximately 150 miles, as the reduced engine dimensions allowing increased fuel capacity.
 
In summary, the T44 medium tank meets all of the required design specifications:
It is 90,000lb unloaded
The fenders fold up to ensure a 129” maximum width (otherwise 135” width)
The upper frontal plate is 3” thick sloped at 80 degrees from vertical, giving an effective line of sight thickness of 17”
The side armor is 3” thick
The power to weight ratio is at worst 16hp/ton (loaded, 810hp engine) and at best 19.6hp/ton
The tank has a crew of four: Driver, TC, gunner, and commander.
The primary armament, 120mm gun T123E7, is capable of firing both antiarmor and high explosive projectiles.