Collimatrix

In general, this tank was a mix of some features the judges really liked, and some they really, really disliked.  There were a number of minor problems that could likely be ameliorated during a prototype development program, as well as a number of issues that the judges felt would require extensive re-design.

 

Tank Interior Automotive and Systems Layout: 

 

The judges had the most complaints about the internal layout of the vehicle. 

 

The autoloader design is questionable in several ways.  The access to the autoloader is not ideal.  The autoloader can be filled either through the driver's position with the shorter rounds, but necessarily needs to be reloaded through the fighting compartment to re-fill the longer rounds.  From the inside of the fighting compartment there is no aperture that the crew can access the autoloader from except the aperture behind the spanning tray, since the spall shield gets in the way from all other positions.  Therefore, the autoloader will need to be laboriously reloaded one round at a time by passing the rounds to the fighting compartment, or driver's position for the shorter rounds, advancing the autoloader one position, and putting the ammunition into the slot in the magazine.  This is no different, in terms of time and labor, than the procedure for loading up a T-72, but the notion that this arrangement would allow for particularly fast re-armament of the vehicle, as claimed in the final submission, is clearly incorrect.

 

The judges are dubious about the autoloader design being capable of handling both two piece and unitary ammunition.  It is not clear how the autoloader does this from the pictures shown.  An autoloader that can handle both types of ammunition is surely possible, but it would require special considerations in the design of the rammer, raiser, and other parts that are never elaborated upon.

 

The judges are generally unconvinced by the design of the powertrain.  The two main problems are the radiator design and the transmission design.  The specific power of the engine is believable; basically identical to the historical AVDS-1790, but the engine is a water-cooled design rather than an air-cooled one.  The judges felt that the overall package size of the engine was slightly optimistic, however.

The vehicle is described as having a T-55 style cooling system, which, given the dimensions of the engine bay was seen as somewhat optimistic.  The system is rejecting a lot more heat than the cooling system of the T-55, due both to the larger engine and the more complex transmission, and it is squeezed into the very margins of an already cramped engine bay.  More worrying is the degree to which the overhang of the turret bustle would interfere with the airflow into this cooling system.

 

The judges are utterly unconvinced that a "CD-1750 crossdrive-type eight-speed manual gearbox, mounted in VPK-3B powerpack, able to handle much greater power" would be able to fit in the space allocated.  Let's unpack that description a bit.  The Allison Crossdrive transmissions, first developed for the US post-WWII heavy tank program, would go on to faithfully propel every tank from the M46 to the M60, as well as the Israeli Sho't Kal, which is more or less an M60 that's wearing a Centurion's skin.  The Crossdrive is a fairly bulky transmission, compared to the simpler Soviet tank transmission, but it does economize on space by using a small number of propulsive gear ratios, which it can get away with thanks to a hydraulic torque converter, and by the fact that it uses planetary gearsets, which is very compact relative to the power they can handle.

 

The cross-sections of the Object 138 that the judges were shown when they asked for clarification show a very compact, essentially cylindrical package reminiscent of the transmission design of the T-72.  The transmission of the T-72 consists of two planetary "half transmissions" which are just about the smallest practical way to power an armored fighting vehicle in that weight class, with the trade-off being that they limit the tank's maneuverability.

The judges find it plausible that a transmission that combines the mechanical properties and design advantages of the Allison-style crossdrive could be combined with a cylindrical form factor.  But certainly not as described.  If the vehicle has eight speeds, then it is not economizing on gear count (and wear) by using a hydraulic torque converter.  And exactly what is meant by a "manual gearbox" is unclear, but generally speaking this phrase means that the vehicle uses a layshaft-style gearbox rather than a planetary gearbox (but this is just a convention; there are planetary gearsets that are manually adjusted and layshaft gearsets that are automatically adjusted).  So... if it doesn't have a torque converter and it doesn't use planetary gears, how exactly is this transmission similar to an Allison crossdrive?  The only thing the judges could think of that this could mean is that the vehicle uses a triple-differential steering system, the same as the Allison.

There are a number of historical tanks which have used layshaft gearboxes with no hydraulic components and triple differential steering.  The Tiger and Churchill both come to mind.  Given the size of the transmission that those tanks had, and that they were transmitting much less horsepower, the size and power of the transmission of the Object 138 seems wildly unrealistic to the judges.

 

The judges were not pleased with the decision to place the additional ammunition within the protected volume of the hull, next to the driver.

 

The rearmost road wheel swing arm is too close to the drive sprocket, and will hit it if it articulates within the specified range of motion.

 

The judges have doubts about powerpack swaps.  Even with the turret at the 4/8 o'clock position, it looks like a tight squeeze.

 

Ground pressure is slightly above threshold.

 

Crew Amenities:

 

This is a mixed bag.  Much like the early models of T-64, the design of the autoloader does not permit the driver to enter the fighting compartment.  This problem cannot be fixed without a complete re-design of the autoloader and its spall protection.  Furthermore, the driver's hatch is utterly unusable when the turret is pointing even somewhat forward because of the enormous overhang of the armor package over the hatch.  By the looks of it, the turret will need to be at least at the 4/8 o'clock position in order for the driver to get in and out.  While the People's Auditory Forces do appreciate ensuring that only the most staunchly patriotic soldiers will become drivers, by giving they/them no means to escape upwards when the turret is forwards, by giving they/them no way to escape into the fighting compartment whatsoever, and surrounding them with combustible ammunition, they also feel that increasing the mortality rate of the driver so much relative to the rest of the crew violates the principles of absolute equality of outcome that the DPRC stands for.  Sometimes rapid egress from a tank is necessary, e.g. when the tank is on fire.  Auditing teams found the relative lack of means of escape for the drivers to be borderline idolatrous; nobody should be forced to have that much faith in the armor protecting them.  The only protection they should instill that much faith in is the eternal word of L. Ron Hubbard.  On the other hand, locking the drivers in the tank during combat is certainly an effective means of preventing desertions through cowardice.

 

The design of the coaxial machine gun is puzzling.  It is described as a 7.62 PKT; so far so good.  But it is described as feeding from left to right and using a disintegrating link belt.  Normal PK machine guns feed from right to left from a non-disintegrating belt.  Fine; we'll suppose it's some sort of post-apocalyptic copy of a PK, and the engineers have made a few small tweaks.  That is certainly possible and reasonable.

But why place a gun that feeds left to right on the right side of the main armament?  This is almost the least convenient possible way to do things while still technically working.  The fact that the coax breech is on the right side of the gun tube means that the commander must be responsible for reloading the weapon.  But it also means that the ammunition belt feed starts on the side of the receiver of the machine gun opposite from the commander.  This, combined with the very forward position of the trunnions means that reloading the coaxial weapon is ergonomically difficult for the commander.  Furthermore, why is it the commander's job at all?  The commander is the overall decision-maker in the tank, and distracting xir with such non-command related busywork is detrimental to the commander's overall situational awareness.

Placing the coaxial machine gun on the commander's side of the gun tube would have made some sense if the other side of the gun tube were taken up with an articulated, backup gunsight.  But the detailed description of the fire control system makes it clear that there is no backup gun sight!

 

The lack of a backup gun sight is a serious oversight itself, but compounded with some other flaws of the FCS design, it becomes downright alarming.  The main armament has excellent depression, but the optical rangefinder, due to being a copy of the design from the T-64/T-72, cannot depress as far as the gun itself can.  Due to ballistic drop of the rounds, the rangefinder needs to be able to depress at least a few degrees more than the gun tube can in order to range targets for the gun to service at max depression.  This flaw was particularly puzzling to the judges.  If the team had simply copied the rangefinder design from the M48/M103/M60, this would be a complete non-issue and the rangefinder would work better due to longer base length.  Due to their location far aft of the lengthy armor packages, and without great elevation, the gunner's primary sight and the commander's sight both have limited depression angles, although not quite as badly as the rangefinder.

 

 

This cross-section clearly shows that the arc of the gun breech during elevation and depression intersects with the location of the arms of the commander and gunner.  While the judges were impressed by the design team's commitment to fighting ableism by finding roles suitable for amputees in the People Auditory Forces armored corps, it is suggested that making scores of new amputees is perhaps not the best way of accomplishing this goal.  In any case, if it does turn out to be the best way of accomplishing this goal, there are more expeditious ways of producing amputees readily available to the PAF.

 

On the debit side of things, the fire control system is absolutely excellent aside from the field of view issues mentioned earlier.  The idea of having a quasi-HUD to improve crew situational awareness is an excellent one, and actually an amenity that many 21st century historical vehicles largely lacked.  The gun-follows-sight digital fire control system is described in admirable detail and sounds excellent and effective.  The communications system was surprisingly well-described, and included good and useful features.  The inclusion of fire extinguishers and a boiling vessel is also thoughtful and propitious.

 

Firepower:

The firepower of the vehicle is generally excellent.  The gigantic, smoothbore 125mm gun is more than adequately lethal, and should have ample growth room if future trends in tank ammunition recapitulate those of the pre-war past.  No two ways about it, that is an extremely killy main gun. The pressure limits might be exceeded a bit with the full-caliber AP if no allowances are made in terms of propellant mass and grain design, but even if the pressures are dialed back a bit to maintain the piezometric limit, it should reasonably meet spec. 

 

The judges had some concerns that the main armament might be badly out of balance, especially with the mantlet, and require a large equilibrator.  This unbalance would also complicate the stabilization, but not to an intractable degree.  The judges were somewhat skeptical of the claims that the remote weapons station could be fully stabilized on the move.  It clearly elevates around an axis near the rear of the weapon, which would create an enormous moment of inertia and unbalance.  The judges were likewise skeptical of the gun-launched ramjet round.  The description did include performance charts, but none of the figures necessary to sanity-check the same like fuel fractions.  The judges are very skeptical about the use of SACLOS guidance on this weapon.  SACLOS guidance works well on subsonic ATGMs.  This weapon is moving an order of magnitude faster.  However, even without the ramjet round, the gun is quite satisfactorily killy.

 

Armor Layout:

The armor layout provides generous protection arcs measured on the horizontal.  Protection against elevated threats is less impressive.  The armor arrays are in general arranged in a very "brute force" way, and provide poor mass efficiency for the protected volume.  Preliminary estimates (based on approximate area and areal density of the arrays) by the judges suggest that the mass estimates provided by the team do not converge near the mass claimed for the vehicle, nor to a realistic vehicle armor mass fraction.

 

The design of the turret side arrays is puzzling.  The radio sounds bitching, but why was so much mass used to ensure it is protected?  The layout of the ERA is simply sloppy.  Why does it only cover the center of the turret roof?  Why is the ERA on the skirts vertically arranged when it is clearly designed to deal with threats originating along its long axis?  Why were the various optical instruments allowed to create so many holes in the ERA coverage?  Why do the extremely wide mud guards not have ERA on them?  Why is the hull so dependent on ERA for meeting reference threats?

 

On the plus side, the APS system described seems reasonable and effective.

 

In general, this tank was felt to be the more technically conservative design overall, but it featured some strange ideas that the judges weren't entirely sure they understood the rationale behind.  The problems the judges foresaw with this vehicle seemed largely to be soluble during a prototype development program.  Where the armor is thick it is outstanding.

 

Tank Interior Automotive and Systems Layout: 

 

The judges are entirely unclear what the advantage of placing the engine in the front but the drive sprockets in the rear is.  Even stranger, the radiators are in the rear!  This is convenient for the transmission, but it also means that there are hot coolant lines running through the hull of the vehicle.  On that subject, the idea of using the radiators as swing-out escape doors is patently insane.  The crew would need to crawl over the transmission, which is only about 90% efficient on the best of days and thus very hot, and then shove the also very hot radiators out of the way.  The judges are dubious that even with generous amounts of asbestos that this could be made to work.  But if the tank has cooled down, the swing-out radiators would be very handy service access doors.  So they are very useful, just probably not for the stated purpose.

Presumably the transaxle from the engine to the transmission runs along the left side of the vehicle, or possibly down the middle of the belly fuel tank so it doesn't get in the way.  The fact that the engine and transmission must be removed separately is a downside.

Fire control system overall seems reasonable, however, the judges have doubts about a radar rangefinder on a tank.  They've been tried, and have generally not worked well due to clutter.  The dish is fairly large, however, so perhaps the beam is narrow enough to avoid the worst of these problems.  The optional stereo rangefinder appears very doubtful.  Because it is at the back of the turret, it cannot depress very far before its view is occluded, and therefore is not useful when the tank is hull-down.  This is a secondary concern, since the tank appears to be primarily missile-armed and the stereo rangefinder is optional equipment.

 

The judges are not sure quite what is meant by the road wheel travel figures.  Either the road wheel travel is typical of an M48/M60 type tank, or it's actually slightly better than a Leo 1.  If it's the latter, then what's actually holding the tank back is the T-72 style transmission, since the vehicle has excellent specific power.  The T-72 style transmission is very compact (which is clear from his internal schematic), but does not give the best maneuverability.  Incidentally, if it is a T-72 style transmission it cannot also have a synchromesh, as T-72 style transmissions are entirely planetary.  We suspect that Toxn calculated the MMP incorrectly, and through no fault of his own.  One of the equations for MMP floating around on the internet is wrong and will give half of the actual value thanks to a missing coefficient.  If his vehicle's ground pressure were actually 114 kN/m² then it would have lower MMP than an M113!  The (more realistic) figure of 228 is still close to threshold.

 

The specific power of the engines is extremely conservative.  They have slightly more displacement than the reference AVDS-1790, but produce just over two thirds the power.  The DPRC will have no difficulty furnishing such motors.

 

The stowage of all the gun and missile ammo either in protected ammo racks or in exterior bins (at least in 85mm variant) is excellent practice.

 

Crew Amenities:

 

Crew comfort and ergonomics seems like a mixed bag, but mostly good.  The driver's position is well forward of the turret, so it appears that the driver can get in and out unless the bustle or gun tube is directly over them.  The driver also appears to have excellent access to the turret basket, since there is no ammunition on the turret basket floor or anything else in xir way.  It is unclear why the gunner's primary sight is directly in front of the commander's cupola.  Despite having a fuel tank and possibly driveshaft running under it, the turret interior is reasonably roomy.

 

Firepower:

 

Firepower seems reasonable assuming that the tank can be configured for the likely enemy beforehand.  The performance for the full-caliber 85mm AP round seems... optimistic.  It is somehow penetrating about 70mm more at 2km than the KwK 43 with only about 10% more projectile kinetic energy at the muzzle.  But perhaps with the ultra-hard steels and better shell aerodynamics unavailable to the Germans, this is possible.  The 85mm gun is just barely adequate to destroy the Norman with existing armor arrays.  With anything more advanced, the 145mm low-pressure gun will doubtless be required.  The tandem warhead 145mm round sounds extremely impressive.  The fact that such an upgrade is already planned is good future-proofing.  However, it seems that the revised ammo stowage for the 145mm version compromises the otherwise excellent safe and isolated ammunition stowage layout of the 85mm variant.  Furthermore, the low muzzle velocity, coupled with the somewhat dubious rangefinder installations would probably not lead to the quickest time-to-hit.

Both NUB and LUB ATGMs are capable of knocking out the Norman and then some with its existing armor packages.  However, the LUB is completely insane, and it does not seem likely that a mass-practical up-armor package could be developed that could stop its fantastic 1650mm tandem-charge penetration.  This weapon would also be useful for destroying large bunkers at a safe range, as the behind-armor effects of such a gigantic shaped charge would be considerable.  The judges are a little dubious about the resolution of a spin-scan based radar reticule tracker.  The IR unit, however, seems perfectly in line with what one would reasonably expect.  Judging by the graphics, it is significantly overbuilt.

 

Armor Layout:

The armor protection seems decent, but it is held back by a sentimental desire to protect the crew.  Hits to the left side of the hull from the frontal quarter seem very likely to disable the engine, as it it does not appear that there is a side armor array protecting the engine the way there is protecting the driver.  Ammunition is almost entirely isolated, at least in 85mm variant, and entirely in the turret.  The side skirt with the massive space seems like a good idea, however, it appears to be a monolithic piece of steel, and this would seriously hamper any sort of track repair and maintenance.  The turret ring seems a little exposed.

 

The roof armor protection is notably very good, and the turret roof will stop Cascadian ATGMs at two degrees over what the solicitors thought was a very optimistic angle.  The turret protection against plunging fire HEAT threats is very good, and should give this vehicle the edge in MOUT and counter-insurgency operations.  The hull protection against KE is noteworthy; the thickest parts of the hull can shrug off 105mm KE threats from ninety degrees off axis!  That's a greater protected arc than the turret enjoys!  PAF tactical theorists have been kept busy arguing about theoretical "hull up" fighting positions, which might possibly involve floating hills that could take advantage of this unusual armor layout.

 

A preliminary areal density analysis did suggest that this design converges to a weight close to what the design team predicted as well as to a realistic (but high!) armor mass fraction.