Dragonstriker

If it's the report I read, they basically called it a failure because it could not transport a squad in perfect silence, with complete protection from any and all arms, at 100kph, with perfect reliability. I didn't notice if they thought it was over priced as well...

So, Sherman vs Panther is a topic that has been chewed over on this forum until only gristle remains. I accordingly have very little to add except to urge the newer members to dig into some of our older threads.
 
In terms of chronological progression vs what hindsight tells us - as @Sturgeon has stated, a T-44/T-54 was entirely within the state of the art in 1939. If aircraft seem to have more quickly arrived at a local optimum, it's partly a function of more resources being poured into them than tanks*, partly a function of the relative utility of outdated models^, and partly a function of different operational and strategic tradeoffs.
 
Tanks are rigidly constrained by fuel supply lines, bridge sizing, tunnel width and train gauges. The result is that you want to get along with the smallest, lightest, most mobile vehicle you can until such time as it isn't tenable any more. With aircraft, the major limitation of runways only kicks in at the very frontline, and accordingly puts hard constraints only on shorter-ranged types such as interceptors and tactical support aircraft. Even then, this mostly bites around the point where jet aircraft become common and landing speeds start to balloon.
 
 
*Resources put into tank vs. aircraft production in WW2 are uniformly almost impossible to directly quantify given wildly fluctuating budgets, the different strategic resources needed by each, the inaccuracies of stated prices, and the fact that all the services kept their own accounts. On the Nazi side of things, wild swings in allocation were frequent but the luftwaffe nearly always ended up with the lion's share of resources (especially scarce resources such as aluminium). As for the Army, only around 20% of their budget went into tanks. The production figures of all combatant nations reflect this: around two aircraft were produced for every tank.
 
 
^An outdated tank can still provide valuable frontline service, while an outdated fighter or bomber is dead weight.

My understanding is basically every tank had that problem once it was penetrated - might be better to say the later wet stowage Shermans were unusually safe.
 
I can't find a definitive source but see Table VIII here and the discussion here.
 
Edit: also this https://www.tankarchives.ca/2016/03/tank-crew-losses.html

The various design competitions and the judgings thereof are a good resource for seeing how to approach tank design (especially in a fictional context).

Something to think about is that the tank that won the "WWII-era" (Cascadia) competition ended up a lot like a T-55. In theory you could have been making T-55s from 1939 on. They didn't, because actual chronological development doesn't work that way. In 1939, what is a T-55 designed to kill?

There were many more fighter programs than tank programs, many of them producing dogs that never went into service. Of the ones that went into service, most were a disappointment in some way. Of the few that weren't, only one or two were outstanding. This gives you a good idea of the numbers involved: around 240 types used or tested, including foreign types, trainers, utility aircraft etc. Of those, maybe half were used in any great numbers in service. Of that 100-ish aircraft, perhaps two dozen rose above the level of mediocre. And of that two dozen, a handful are considered superlative in their class.
 
Aircraft design is very fiddly, and requires a mix of easily-ascertained factors (power-to-weight ratio, wing loading, armament etc.), hard-to-ascertain factors (top speed, turn times in various configurations, landing speeds) and factors which defied empirical modelling and could only be found by experiment (stability, stall characteristics, maintenance and service niggles, random engine/landing gear/aerodynamic bugs etc).
 
Making a good aircraft in WW2 was as much alchemy as science, and resulted in a lot of dead test pilots. Tanks were actually comparatively easier to design, and accordingly got designed by lesser talents on lower budgets (see, again, the example of British tank building in WW2, which was the product of a bare handful of second-tier engineers). Even today, the best mechanical engineers are mostly doing aviation and aerospace. 
 
 

As for what a 1990s tank would realistically look like, by the 1990s most tanks were really samey.
 
Powerplant:  The earliest tanks with diesels were experimented with in the 1930s, I believe either the Japanese or the Soviets were the first.  By the 1940s the advantages were obvious, but de-rated aviation gasoline engines were reliable and already in mass production, so many countries stuck with those.  I'm less clear on the rationale for the Germans keeping gasoline motors as theirs were not aeroderivative.  In any case, there actually was a German tank diesel program, it just went nowhere.

By the 1990s there were pretty much two realistic possibilities for a tank powerplant; either a turbodiesel or a gas turbine.  1990s MBTs are about half armor by weight, so they're very sensitive to the compactness of things.  Turbocharged diesels don't have amazing power density, although with a lot of careful engineering they can be made competitive, but they have very low fuel consumption and lower waste heat rejection requirements than gasoline engines.  Once you factor in the volume of the engine plus the volume of the fuel plus the volume of the cooling fans, and the strategic mobility advantage the fuel-sipping diesel, it's definitely coming out ahead of the gasoline motor.

Gas turbines do not scale down particularly well.  Very large gas turbines like the 33,000 horsepower Rolls Royce WR-21 naval gas turbine in the Type 45 destroyer achieve 42% thermal efficiency, which is like middling efficiency by diesel standards.  A gas turbine that will fit inside of a tank is much less efficient; realistically about a match for a gasoline engine in terms of specific fuel consumption when it's at design point and much worse if it's idling or doing any kind of stop and go.  Gas turbines also need beefier air filters than diesels due to much higher mass airflow through the engine.  However, there are still a number of advantages that must be taken into consideration.  Gas turbines are (very nearly) completely self-cooling, so while there will still need to be cooling fans to keep the transmission cool, the total powerpack losses to cooling power will be smaller and the ballistic windows from the ventilation will be much smaller.  Gas turbines with a free power turbine (which is most of them) have a very different torque/RPM characteristics from a diesel; they produce max torque at their lowest RPM and max power at their minimum torque.  These are very favorable characteristics if you want to keep the transmission small (although the Abrams' XR-1100 transmission was, as I understand, designed to work with both the AVCR-1360 and AGT-1500 so it likely does not take much advantage of this effect).  Gas turbines are easier to start in the cold.  Gas turbines have very little vibration because their moving parts rotate rather than reciprocate.  Gas turbines are actually multi-fuel, no questions asked and no mucking around with adjusting the engine to suit the fuel.  The Brayton cycle uses continuous, constant-pressure ignition which simply does not care about octane numbers or cetane numbers.  Finally, it's easier to design gas turbine fuel burners so they produce very little smoke than it is to ensure that a diesel produces very little smoke due to the much different fuel burn stoichiometry of a gas turbine.  It should be noted that not all gas turbine designers have actually succeeded in doing so, however.

A gas turbine good enough for a tank would be roughly similar to a turboshaft for a helicopter, albeit tweaked more for better fuel consumption than for absolute power to weight ratio.  The list of countries that can design very good turboshaft engines is quite short, but then so is the list of countries that can make high specific power diesels.  If tank-sized gas turbines performed as well as ship-sized ones this would be no contest, but they don't so either choice is competitive and it's pretty ambiguous which is "best".  But most countries in the world realistically do not have the luxury to pick and choose between a top of the line diesel and a top of the line turbine.  Interestingly, the UK is in a position to make such a choice and they still managed to fuck it up somehow by fielding a tank diesel that's 300 horsepower short of its stablemates.  The French hyperbar engine is a turbocharged diesel, just tweaked for very fast throttle response and compactness at some expense to efficiency.

Armament:  By the 1990s, advances in digital fire control systems largely rendered gun-launched missiles obsolete.  There was probably still a case for them as a sort of long-range precision round for swatting at helicopters and the like, but that role could also be filled with something like M830A1.  There were various flirtations in the mid Cold War era with sorta-kinda howitzer like armament for tanks in the form of medium pressure guns and gun/launcher hybrids, but by the late 1970s there was basically a consensus amongst all sensible people that the tank armament of the future would either be the Rheinmetall 120mm or would look a lot like it.  Even British engineers were aware of this:



In any event, the Soviets taking their toys and going home meant that the world did not suddenly fill with various super-tanks, and tank lethality ended up being more economically improved by advances in ammunition design rather than arming the tanks with larger guns.



You can't go too much larger than current 120mm without requiring an autoloader.

As LoooSeR said, context is important.

During the 1940s, tanks were simple enough that relatively small countries could design and field reasonably competitive designs on their own.  The expertise required for tanks largely overlapped with either other armament industries (tank guns were often adapted naval, AA guns, or field artillery and the engines were often modified aircraft powerplants), or civilian heavy industries (much of the casting/welding and transmission design could be readily adapted from car/train/ship making industries).

By the 1990s, however, tanks were much higher tech and a lot of that tech was much more tank-specific.  It should be possible to adapt a helicopter turbine or heavy prime mover engine to work in a tank.  Fabrication of the hull could still probably be done with expertise from other industries.  Production of the special armor packages, transmission and running gear would require tank-specific knowledge but not necessarily tank-specific industry.  Production of the gun, fire control systems, and other combat electronics would by that point require very specific knowledge and would overlap relatively little with too many other things already in production if it were a nation's first tank.

I think it's instructive to look at the smallest/poorest countries that have produced their own tanks.  Romania was able to produce the TR-85, albeit in somewhat limited quantities, and they didn't design their own gun, and the turret and hull design are at least based on the design of the T-54/55 albeit very heavily modified.  As far as I can tell they did design their own engine and transmission, which is quite impressive, but this took some time and all the while they were cribbing notes off of foreign designs.  No shame in that; high specific output diesels are not easy to design.

Israel designed the Merkava, which has a completely original hull and turret design, locally designed suspension and tracks, and locally designed special armor packages and fire control on the later models.  The engine is either US or German designed, and the transmissions have been US, German or Israeli designed based on the mark.  The gun was a straightforward clone of the M68, and later a locally designed version of the German 120mm smoothbore.  Both of these guns are compatible with the wide range of ammunition in either caliber, although Israel has a local ammunition industry capable of designing and producing its own tank gun ammunition (which in some cases has been widely adopted outside of Israel).

South Korea has produced two MBTs locally, the K1 and K2.  The former had a great deal of assistance from Chrysler, but the latter appears to be a largely local effort.  Early K2s had a German designed engine and transmission, but these are eventually to be phased out and replaced with locally-designed equivalents.  I believe the tracks are German-designed.  Not sure about the suspension.  The armor packages and fire control system are locally designed and manufactured.  The gun is some sort of version of the German 120mm, although again South Korea is capable of designing and producing their own ammunition.

Turkey, which has roughly the same size economy as South Korea if we discount their current economic woes, has had a much harder time developing their own MBT.  Despite considerable help from South Korea, they have struggled to develop their own engine and transmission and are currently dependent on political good will from Germany if the project is to go forward quickly.  I don't want to give the impression that Turkey has a weak local manufacturing sector or is a stranger to high tech industries.  Neither is true; they are actually capable of producing their own helicopter gas turbines, combat UAVs, missiles, and a variety of other quite challenging materiel.  Turkey has, current monetary woes aside, a well diversified and fairly well developed economy.  They're just not a match for South Korea, which has an extremely well-developed heavy industry and electronics sector relative to the country's size, natural resources and population.  Israel has an even smaller population and GDP, but their defense industry is outrageously well-developed for a country of that size for some mysterious reason, and there is abundant local expertise in the design of complex weaponry.

So, any country that is plausibly going to mass-produce a 1990s tech-level tank (and let's be honest, that's not dramatically different than a 2022 tech level tank) is going to need a fairly robust economy, well developed local heavy industry, and a large number of mechanical and electrical engineers.  I think the poorest of the countries I just listed is Romania, with the 39th largest GDP in the world (out of 190-something).  By the 1990s, being able to design and produce a tank on ones own was a privilege reserved for a fairly small number of countries.  Even countries that could plausibly design their own engine, transmission and tracks frequently farmed these out to Germany's Renk and Diehl, respectively.  Alternatively, you might say that Brazil in the 1980s represents the floor economy of a nation capable of designing and producing its own tank, although the entire turret on that vehicle is a British design from Vickers.

So that would be the first thing I would say about designing a 1990s tank; it's not for small nations, and even the rich ones frequently used foreign components.

140mm

Others have said/alluded that "shot traps" aren't really a thing anymore, but I wanted to add that a big part of the reason for this now is that for the most dangerous threats a lot of the tank is simply "all or nothing". Yes it's true that fin doesn't ricochet so much, but a part of this that is forgotten is that modern tank armor is absolutely bursting at the seams, it's as much armor as anyone can stand a vehicle to have, and it's all directed at stopping the biggest threats from only so generous an angle. A really good book to read if you want the story on how tank design went from "okay we'll protect against this threat everywhere" to "we really need to be making compromises here" is Hunnicutt's Abrams, specifically the section after MBT-70. That's when designers in the West had their come to jesus moment.

These armor arrays are so huge that shot traps are simply a cost of doing business (albeit, again, not a terribly costly one in the current environment), because there's no practical way to make a NERA-box that had flush armor arrays like an M48 has.

I think it should be pointed out that shot traps pretty much don’t exist anymore, APFSDS doesn’t bounce or ricochet any appreciable amount, and you can safely ignore shot traps for the time period you’re concerned with. What does make angled armor less attractive is that your protection is not homogeneous across your profile, being thickest at the tip and thinner as you move towards the base, such is the geometry of triangles. I suspect this is why the Leopard 2SG and PL have more square faces than the 2A5. 
 
As for “funny turrets”, if it works for what you need it to, then don’t worry about aesthetics. Teledyne’s low profile turret is “funny”, as compared to practically every other tank out there, but it works, as proven by the M1128 (somewhat). There’s also the “Elke” technology demonstrator, mounted on an M551, that’s even crazier, and I would very much enjoy seeing something like that work. What’s wrong this the halo tank is that the crew is practically exposed, the tracks are complicated as hell, and the ammo seems to share space with the engine. 

Late to this party, but...
 
you're telling us that not only can Americans not do English, Scottish, Australian or South African accents, they can't even do American accents?

Welcome to the forum. Go check out the various competition threads down in the Competitions subforum. We've done... Oh, four or five tank design comps? Should be illuminating.
 

Hi there!

I'm a new user, and found this forum by way of a video on the so-called "reformers". The video also included a screencap of a thread in this forum about some guy called "Black Tails Defense" or something, in which the strangest tank was shown- something with a 145 millimeter... howitzer? 
 
The... sheer tomfoolery of putting a long-barrel world war one era howitzer with eighty rounds of ammunition in a forty-ton vehicle somehow designed to also float... I personally enjoy entertaining the concept of designing fictional tanks for fictional universes. However, I'm critically aware of how limited my knowledge on this subject is. 
 
Honestly, I was more really concerned with the external appearance of the tank to look as "realistic" as possible- no shot traps, no funny "turrets" like on whatever that Scorpion-thingy from HALO was, as well as worrying about details like how to make sure the tank doesn't break down mid-combat and the placement of critical systems like Optics, but I'd also like to know what kind of systems should you use (e.g. Turbine or Diesel, Horstmann or Torsion bar, etc etc) 
 
There's a little thing that I'm doing where I draw up tanks et cetera within the confines of Mid-Late 80s-90s - early 2000s doctrine, and I'd like to ask you, what makes a real tank tick for tanks of this era? How should you go about designing a tank? I'm aware of the fact that one should always design inside-up (critical components such as engine, gun, et cetera up), but what are some of the caveats and nuances inevitably intertwined into it? How should one go about the design process for designing a tank?
 
What's a rough list of features you want to have, and others that you can sacrifice for any given role of a tank? I'm aware that this is like asking, "what should I put on a plane", but let's assume that it's for a tank stuck in, say, the Mid-late nineties, around the Gulf War - Kosovo period.
 
Also, in addition to this, some common questions that I'd also like settled are;

- Diesel, Turbine, or Petrol? Where/When/How should these engines be implemented?
- Rifle or Smoothbore? This debate goes on forever and I'd like some sort of concrete answer. As far as I know, the only forces that use rifled guns use them either out of necessity or reliance on a certain specific type of round.
- Why in god's name would you ever put a 145 millimeter howitzer on a tank?
- Caliber: Is there an upper limit? Is it really worth going above 120mm/maybe 130mm at a stretch when combat won't even happen above the ranges that these guns are effective due to the distances that you can see with optics? At range, Artillery and Missiles have traditionally been more efficient.
- Whither the Autoloader, or Nay? I've seen the Chieftain's video on it, but I personally would like your opinions on it.
- Barrel loaded ATGMs- are they really all that they're cracked up to be? Why/why not?
 
I'd like to strickly restrict this to Main Battle Tanks, as I'd rather ask about Infantry Fighting Vehicles later, in another thread.
 
In short, how the 1990s Tank?
 
Sincerely yours,
 
Aussie_Mantis

Normally, for a decent model, you can run it from the command prompt. You tell it where to find a file with the input settings, and where to put the file with the output settings, and it goes off and does its thing. This is handy because writing a program that can modify the text file of input settings, call the model, and then read the output text file is very easy. So with a fancy model that can be run in batch mode you can easy write a function that takes a setting (e.g. 'bow width'), feeds that setting to the fancy model, and returns something from the calculated results.
 
This is useful because you can do lots of complicated maths involving gradient descent on this. With a black box that takes values and returns a calculated value, you can calculate the partial derivatives for each of the inputs and roll down that hill to a local minima (or roll up to a maxima, whatever). So if you wanted to calculate the required width of bow needed for a certain draw weight (with everything else held constant), the steps would look like this:
you need a cost function that you want to maximise or minimise - for this example, the RMS of (ideal draw weight - calculated draw weight) will give a minimum when you've found the ideal width calculate the derivative of the output with respect to the input by running the model for a box that's a bit thicker and a bow that's a bit thinner increase or decrease the input (as determined by the direction and magnitude of the derivative you just calculated) Then take the gradient again, to see if you've found a minima You can apply the maths for this to an arbitrary number of input variables, and the best part is that someone's already done it for you - scipy.optimize.minimize is a function that takes a black box and an initial guess, and works to minimize the output of that black box function without ever trying to understand it. Any program that can be run in batch mode can be easily fed to optimization programs, so is trivial to optimize.

I think the way to "win" this contest is to develop the most expensive platform possible that sits in the heart of the trashfire envelope.  Make it more expensive by giving it armor and hardening the airframe.  Make it more expensive by equipping it with a cannon that cannot take out tanks, the purported target of the platform.  Upgrade the platform with systems that let it "standoff" even though the platform is aerodynamically constrained to be in or near the trashfire envelope always.  Also, make sure the platform is optimized for CAS instead of the more efficient BAI.  Then put out to the media how the platform can take hits from trashfire that could not even reach other platforms.  Declare that CAS must be performed in the trashfire envelope instead of outside it.  Therefore, the platform in question is "superior" at CAS compared to platforms optimized for BAI/interdiction/strategic.

I also think like, the A-10 has really twisted around people's ideas about what CAS is supposed to be. Close air support is ordnance delivery in close proximity to friendly forces. That's it. We now have this idea that it means some flying turd hovering around a platoon getting JTACs commands and brrrrting at anyone who looks funny. This is a hyperspecific artifact of the way CAS was conducted in the GWOT. But a 'Chief flying in at 800 miles per hour and dropping bombs on enemy positions and then zooming off is CAS, too. A B-52 dropping a JDAM from 35,000 feet onto a ground lased target is CAS, too. CAS is not just "that thing the A-10 does".

This is irrelevant to the question of the A-10, and it also isn't clear to me that in the case of CAS you get a different answer with either premise.

The reason it's irrelevant to the A-10 is that the A-10 doesn't exist as a "repository" aircraft, it exists to pretend to be a helicopter so that Congress doesn't take away scope from the USAF's mission-budget holdings. The USAF (circa 1965) doesn't care about CAS that much, it cares about any kind of tactical air being given to the Army, which it sees as a first step towards the Army being able to recapture scope that was split off from it in the 1940s. And you look at what the Army was playing around with at the time, and it's pretty clear that the A-10 exists primarily as a physical "lid" on the Army's tacair capability. In other words, the Army cannot have any aircraft as capable or more capable than the A-10. That's pretty much its entire purpose (even if no one person was thinking exactly that, there's a reason these things shake out this way).

Now why do I think the domination/repository models don't get you a different answer? Well, simply because fighting wars requires methods of conduct which use assets and which together are based on doctrine. So whether you think of the Air Force as a "battlespace dominator" or as a "plane battery" is irrelevant. It is a battlespace dominator that requires a plane battery and both are subservient to the doctrine. Which one has "primacy" does not change the math. I could maybe conceive of a structure where that did change the math, but it would have to be very tortured indeed to apply to CAS.

Confirmed, the A-10 Threshold is below the Ju 88

The P-47 is crying in its grave that this is her legacy. 

It’s fine, I still understood what you were saying . The Queen E’s were very good, but still suffered from the typical British engineering practice of “penny wise, pound foolish”. 
 
However, this is about her majesty’s admirals, and not their boats, so I’ll stay on topic. I believe Fisher was a more intelligent admiral that the both of them, some of his ideas having very good foresight of future events, also his 2 legacy ships, all big gun battleships and battle cruisers, even if both were not used as effectively as theorized. 

The most remarkable thing to me about the A-10 is how popular it is in Washington. It is an aircraft dumb enough for Congress to understand (and it reminds them of the biplanes of their childhood), so they keep pushing it. And there's enough "turd polishing" grift there for the USAF to go along.

Grunts love the A-10 because it's just as helpless and pathetic as they are, so they feel a strange solidarity with it. Plus, really any air support is welcome.

Presumably step in as replacement marines, same as their last go-around in the pacific.

Mac is one of the most impressive bloggers of our era and really does a bang up job every time he puts fingers to keys. I've referenced him many times.

The A-10 is junk. We should have scrapped them in the '80s, certainly in the '90s after their dismal failure in the Gulf, and bought Tucanos and A-7Fs.

Yeah, the Army would have handled fixed wing CAS better than the Air Force for sure.

Did it ever kill a tank in anger that wasn't on its own side with its gun?