Room at the Top

When I had the privilege of visiting Fort Knox last spring, I put this question to Major General Frederic Brown, Commandant, U. S. Army Armor School: “Will our successors fight the next main battle tank by electronics, or by the seat of their pants?” His answer was characteristically incisive, thoughtful, and precise: “They’ll fight it electronically at the halt, but by the seat of their pants on the move.” A year back, a meeting of LEOPARD 2 and MI users at Munsterlager, West Germany, insisted that the commander should normally fight the tank head-out “to sense the battlefield.” Yet, with one small highly predictable step forward, optronics will allow the designer to offer the user a crew-in-hull tank with these advantages: 0 Swimming with anon-board screen. 0 A saving in weight of around one third, say to MLC 40, with all the combat and logistic advantages that implies. Much improved hit avoidance thanks to agility, low silhouette, and, in particular, a reduction by a factor of fifty or so of the area exposed in hull defilade. Good direct protection, with much improved resistance to side and overhead attack. It is in this last point that the crunch lies. The threat to the main battle tank (MBT) from the tank gun and the surface-launched cruise missile is yielding pride of place to two new threats. The helicopter attack over a wide horizontal arc and, from its chain gun, with a significant angle of descent. Then there is the whole spectrum of overhead attack, exemplified by COPPERHEAD, GAMP and MERLIN, smart submunitions with self-forging fragment (SFF) and shaped-charge warheads, and doubtless before long, short-range terminally-guided ballistic missiles. By the time the next tank comes along, the concept of a narrow, shallow frontal arc, on which a conventional tank depends for its protection against dedicated attack, will be as dead as the dodo. In this article I want to highlight one or two key points and outline the intermediate paths along which user and designer might stroll hand in hand. To achieve this in the space available, I will be brief and sweeping, relying for credibility on fuller discussions of Cliff

GUN SLIGHTLY OFFSET n a I - OR - - - - - - Figure la. Bradley’sand my own in your columns and elsewhere. Luckily, we have wooden if not yet metal realizations of the two extremes - the conventional in the low profile turret of LEOPARD 3 (figure la), and the far-out in the Swedish UDES 40 (figure lb). Very briefly, LEOPARD 3 will have an autoloader (either a turret-basket carousel or a bustle system); a roof hatch to take care of the breech end of the gun in depression; and the commander and gunner up top, possibly in tandem alongside a slightly offset gun. UDES 40 (the “40” being the weight ceiling) will have a crew of three in the hull; a yoke-mounted external gun (in fact, the German 120-mm smoothbore); a primary vision surveillance/ sighting system (VSSS) just above trunnion level; an external system 18

“... One sees tank commanders exposed down to the waist, already halfway to Heaven...” Fig 1 b. (Above) Model of the Swedish UDES-40 shows crew-in-hull layout with yoke-mounted external 120-mm gun, fed by external magazines at the rear of the hull. Fig 1 a. (left) The Leopard 3 concept is more conventional, with commander “up top” in low-profile turret. Several possible autoloader configurations are shown. A roof hatch rises to accomodate the gun breech in depression. capable of reloading the gun in any attitude from external magazines on the hull rear; and integrated compound armor making use of the engine compartment, the contents of the sponsons (including fuel in both cases), and the umbrella effect of the external mounting. Laser Blinding There are suggestions that laser blinding may impose the use of indirect (optronic) VSSSs, thus nullifying the advantage of having the commander up top. Laser blinding is certainly a two-edged weapon; and the enthusiasm by which it has been hailed by some leads me to suspect that it may turn out to be, figuratively as well as literally, a flash in the pan. In any event, improved forms of the techniques once proposed for optical VSSSs against nuclear flash blinding may well provide an answer. Commander’s All- Around Vision I go right along with General Brown and the work on slit vision going on at Fort Knox. I never was able to control a tank closed down - let alone a platoon, a company or a battalion combat team. I have had the privilege of knowing a few American, British and German senior noncoms who could; but they were all superb professionals, of trials crew/senior schools staff standard. The four British ones who spring to mind all finished up as lieutenant colonels! By contrast, no army could withstand the attrition rate tank commanders with their heads out were always apt to suffer, and are almost certain to suffer under today’sand tomorrow’s indirect fire. I am extremely familiar with the course of American and British cupola development through the ’50s and ’60s; I am reasonably aware of what has gone on in those countries since; and I have a nodding acquaintance with the Zeiss PER1 R 17 commander’s sight of LEOPARD 2, a superb device of its kind. With standoff and hindsight, I believe both those approaches were and are wrong. While the Germans and the Soviets had always had a liking for rotating-head periscopes, your designers and ours struggled with fixed periscopes and vision blocks to give the commander uninterrupted, all-around, parallax-free vision. This was not enough, because “enough” information - the theoretically necessary amount - is not enough to give the human brain job satisfaction. The brain requires enough surplus information to be able to evaluate and consciously reject some. No way is the tank commander going to be happy with the amount of inputs he can get from a cupola or a rotating-head periscope - so he sticks his head out and gets himself shot.

One needs to take a realistic look at just what all this conventional top-hamper will keep out, and the answer is - not much. Even with the kind of thickening that might be feasible, a fair hit by a dedicated attack is going to pass through the roof (probably blowing in or off any cupola or hatch), most likely through a crew member, and more likely still into an autoloader carousel placed down below like a stop-butt. So one wants to think about protecting the commander from the scatter and deflection effects of dedicated attack, and from the non-dedicated attack still delivered by the great majority of battlefield weapon systems. This could probably be achieved by an “armored” glass or plastic dome large enough to allow the commander to move his head freely and to use handheld binoculars, rear vision being provided by racing-type mirrors in armored fairings. The washing and wiping of a dome is not an insoluble problem. The dome could be designed to be replaced from inside, thus providing an emergency exit; but a separate hatch, presumably rear-facing, would be needed for normal access. A lift-and-turn or lift-and-flip-over steel lid of the type now used to provide slit vision would protect the dome fully or partly when required. If commanders find domes like this too restrictive, another option is a two-man “armored” transparent hood for the commander and gunner. If they were located in tandem, this would closely resemble the cockpit hood on training gliders and old-fashioned aircraft (the kind with propellors); so one would expect it to be acceptable. The idea of a transparent dome or hood needs to be explored in depth; it could well offer a cheap, light and highly-acceptable solution. The only problem then remaining would be how to leave the commander’s field of view unclut-tered by the primary instrument heads; in recent American, British, German and Soviet photographs, one sees tank commanders exposed down to the waist - already half way to Heaven and just waiting for the first splinter to complete their journey for them. Gun and Ammunition-Inside or Out? Having taken a great leap forward in survivability with the externally-vented 19

“The problem with both these nacelle layouts is they look wrong...” bustle bins of MI, the U. S. user has no intention of letting his main armament ammunition get any closer again. As long as the ammunition is wholly or partly shielded by the turret or mounting, and can blast off or be jettisoned clear to the rear without risk of molten, burning propellant entering the tank, its location is not too critical. One need only to add that the Swedes have done their homework on mounting ready magazines and decided firmly against them. Briefly, they increase the area of the hull defilade target, cause stabilization problems when partly empty, and are apt to leave the commander with the wrong kind of round “up.” User reaction to putting the gun outside is another thing. On the vulnerability to overhead attack of the parts normally inside the turret, my guesstimate is that, if the breech and firing connections are shrouded against non-dedicated attack and secondary effects, the small presented area, the curvature of the exposed surfaces, and the thickness of metal involved make the risk minimal. Shifting the swept overhead volume of the gun outside the armored envelope is the major weight-saver in a crew-in-hull design. Two-Up Configurations Low profire turret. (Leopard 3. figure la). The low-profile turret represents a major advance in the face of horizontal attack, whether frontal or flank, because it reduces the height above trunnions (to turret roof), and thus the presented area, by one third or more. The proportionate reduction of the area exposed in hull defilade is evidentally much higher. But because the length and angle of the turret side is unchanged, this configuration has little to contribute to the level of protection against flank attack. Much more important, it does nothing at all against overhead attack. The turret roof is just as flat, if anything larger, and significantly weakened by the gun hatch. (In fact, I strongly suspect this turret was designed against the classical threat analysis.) The spread-eagling of the crew right under the roof considerably reduces real survivability, the more so if they are sitting on the main armament ammunition! Putting the turret crew in tandem and offsetting the gun slightly could slightly reduce roof area, but I suspect the “other half’ of the turret The Cleft Turret

Figure 2a.

ie Two-Man Nacel Figure 2b. e Cleft turret layout seen in Fig. 2a, above, has some advantages but the cleft presents an effective shot trap not easily overcome. The two-man nacelle, Fig. 2b, resembles tandem aircraft cockpit layouts, offering good visibility with plastic dome. above ring level is needed for electronic and power packs. Any weight saving is probably taken up in thickening the turret roof and sides - or certainly ought to be. I would assess this as a useful if conservative product improvement to LEOPARD 2, which might have application for MI, but no way as an occasion for celebrating the birth of anew half-generation. Cleft turret: (figure 2a). The need to reduce the area of the turret roof and increase its level of protection is as important as to make the cleft turret rear its ugly head once more. This is a step in the right direction in that it allows the turret crew to be placed in nacelle-like pods which can be shaped to optimize protection. It also lends itself to external autoloading from safely remote magazines (see UDES 40, figure la). But is still suffers from the ladies’ cocktail party problem - What happens when somebody drops something down the divide? Unless one expends an absurd amount of weight 20

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(One each side)

I COLLAPSIBLE SEAT FllTlNGS Finure 3. armoring the inward-facing surfaces, even a conventional 81-mm mortar bomb or 105-mm shell, nicely tamped by the walls of the cleft, is going to wreak havoc. Two-Man Nacelle: (figure 2b). If one takes the overhead threat seriously, a two-man nacelle looks attractive. It is a classical aircraft configuration and therefore likely to have high user acceptability. It can be shaped to present some very interesting compound angles to attack from most directions, including above. Space permitting, it could be bulged to accommodate compact armor arrays. Given careful design, there need be no serious HE pockets. The turret crew can touch each other and converse without aids in the standby state. The plastic hood could be side-hinged, and protected by a steel lift-and-flipover lid hinged in the same place as the hood. Instrument heads could be accomodated in the sloping sides and front, clear of the commander’s natural field of view. The questions are: how far one could offset the gun to get a roomy nacelle within a compact and streamlined silhouette; and whether the out-of-balance torque of the nacelles would be acceptable in a stabilized system. I do not have recent enough data on turret races or powered mounting gears even to ballpark these. But with an external gun, one can reduce the trunnion reaction, and hence the slew couple for a given offset, by around 75 percent - 50 percent by muzzle braking (as in UDES 20 1, and 50 percent of the residue by doubling the recoil length. So there may well be a technically acceptable arrangement. One-Up Configuration (Figure 3). The only interesting-looking “one-up” layout comprises a central (i.e., not offset) gun on an external yoke mounting, with one side of the yoke expanded into a nacelle for the commander, and the gunner either underneath the gun (as in UDES 20, figure 4, and probably UDES 40 ), or below hull-roof level on either side (rather as in the compact M60A2). Since the gunner traverses with the gun, he can have an optical surveillance and sight head, together with any other sensor heads, at the same level as the commander. The periscope tube and other links could be run up inside the gunner’s half of the yoke, together with the elevation drive for the gun and, if required, drives for the VSSS. This would allow commander and gunner to split the surveillance task, as now. There is unlikely to be enough space to give the commander a rest position in the hull; but he could probably touch and converse with at least one other crew member, and could be evacuated into the hull by collapsing his seat. Otherwise, most of the arguments deployed for the two-man nacelle apply here too. One has now gone far enough from the conventional tank to achieve considerable weight saving and reduction of target area in hull defilade. The only tangible drawbacks are the loss of a second pair of eyes physically up top, and limitation of contact between commander and gunner. The problem about both these nacelle layouts is that they look wrong; but the ugliness may well be in the prejudiced eye of this beholder. Pop-up Configuration Pop-up Commander: In UDES XX 20 (figure 4), the commander, whose station is in the hull forward and right of the mounting, can pop up in a cylindrical armored sheath to bring his eyes to (or just above) trunnion level, retracting his station when the gun is fired and on the move. Quite simply - and there is little disagreement about this among the Swedes or anyone else - this is entirely acceptable in the role for which UDES XX 20 is designed - a high-mobility, moderately protected antitank and direct-support gun for infantry brigades in extreme terrain. It is a nonstarter for MBTs and the like. Pop-up Gun: (schematic based on a rejected solution for UDES 40 @gwe 5) ELKE prototype (figure 6 ) ). This has to be the design solution around which controversy is gong to rage. It may in the end prove to be a sound one; but my fear is that it’s superficial appeal will generate such ahead of steam among users as to force designers in a technologically dubious direction. I have rehearsed the arguments at length elsewhere, and will just summarize them here. First, one must distinguish between ELKE, a contender for the light mobile protected gun (LMPG) role developed on the M2/M3 hull as a variant of the improved TOW vehicle (ITV), and a fully-dedicated MBT successor with a pop-up gun. ELKE is broadly comparable to UDES 20 and could provide the basis of a highly cost-effective solution in that group of roles. I will base discussion on the rejected UDES 40 concept (figure 5 ). This seems greatly preferable in terms of survivability to proposals with under-gun carousels, even if the crew is in a separate compartment in the hull. Rheinmetall’s bustle autoloader, a rational development of the MI stowage system and now, one gathers, the preferred system for LEOPARD 3, is fine as long as it does not enlarge the silhouette of a slimline turret or an external mounting. The pop-up gun makes its own case at a glance, so one need only look at the cons. This concept, like most of the others, is fine when you are sitting 21 nicely in “turret defilade” (the quotes because there may be no turret). To fire, you just pop up the gun - no need to move even. But it is going to take a finite time to get the gun up and ‘laid’ and when you are caught on a forward slope this is going to seem like an infinite time! If you have to keep the gun raised when you are in contact and exposed, there seems little point in retracting it at other times. The next snag affects user and designer alike. For an external mounting layout with the primary VSSS at the top, the trunnions need to be only 250 to 300-mm above the hull roof for a 10- degree depression. But if, as with the pop-up gun, the VSS is at the front of the hull roof, the gun in depression will have to clear the front of the VSSS heads as well and this may mean doubling the height of the trunnions above the hull roof. For starters, this will result in a significant change in the height of the vehicle’s mass center when the gun is raised or lowered. Unless a pillar mounting proves acceptable - and this looks as improbable to me as it evidently did to Sven Berge and the Swedish users - a yoke mounting with a retraction depth of 500 to 600-mm is going to put back into the armored envelope most of the expensively armored air that one has at last succeeded in eliminating. On ballpark figuring, raising the gun in under five seconds is going to take between 10 and 20 kw, admittedly not an impossible demand in terms of electrical fighting loads for modern MBTs. But to my mind, the crunch point lies in accuracy of fire. With the VSSS in the hull, even a muzzle reference sight (MRS) will not reestablish zero when the gun is raised unless the height between VSSS axis and bore axis is constant. I just cannot see a hope of holding that height to the requisite accuracy, perhaps plus or minus 0.1 mm, when the gun is repeatedly raised and lowered in a dirty battlefield environment. Possible Directions of Development All these compromise solutions have one thing in common. They make my hackles rise; and I seem to bristling in good user and technical company. The U. S. Army Armor School did not lightly launch itself on the quantum jump to a crew-in-hull layout. Now it has landed safely, with the Surrogate Research Vehicles (SRVs) and the Tank Test 1 Bed 0“B) to show for its boldness; to allow itself to be dragged back into the murky waters of compromise would, I am sure, be greatly against U. S. and NATO interests. On the other hand, there seems every likelihood that the American user, like his German opposite number, will put his foot down and demand room at the top. There look to be two paths which could turn a fruitless confrontation into a concerted step forward. They are convergent, or, at worse, parallel, and each has strong attraction on its own. The LMPG Approach: There is an acute if not yet fully acknowledged need for a Light Mobile Protected Gun (LMPG) of equivalent quality to M2 and M3. ELKE (figure 6) is a candidate for this role. But it would also be possible to bring in a 105-mm, or even the 120-mm smoothbore, on the M2/M3 hull (on the same lines as the German and Swedish 105-mm MARDER rigs) using an external mounting and a trunnion-level VSSS. With German and Swedish experience to draw on, development should not be too costly, protracted, or problem-ridden. This LMPG would be paired with the M2 or M3 in various organizations and roles, and would not normally be used by tactical commanders; so it would have to have a two-man crew. This would both fill an immediate need, and give the user a chance to get his teeth into the problems of crew-in-hull layouts. In parallel with this development, one might forsee a major product improvement of MI, using one of the compromise solutions outlined above. The Gun Tank/IFV Pair The other path is signposted by Fort Knox’s recommendation of an integrated combat arm for the 86 force structure, and by two recent pieces of German user opinion. (I use the term “gun tank,” incidentally, because this could be an MBT, and LMPG or something in between, like the (IDES 30 the Swedish-user rejected.) One gathers that MARDER 3, if it ever happens, is to have a two-man turret like M2, highlighting the need to use two pairs of eyes backed with both optical and optronic aids for the surveillance task. On the tank side, there is some wavering about tank commanders fighting opened up, but none at all about platoon commanders having to keep their heads out most of the time. These two 22

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\ \ Figure 7. Fig. 4. (Top left) The UDES 20 layout puts the TC in the right front of the hull in a “pop-up” armored sheath. Fig. 5. (left) UDES 40 concept placed the gun, rather than the TC, in a ‘‘pop-up’’ mounting. Fig. 6. (Right) ELKE prototype has crew in hull and elevated gun on Sheridan chassis. Fig. 7. (above) Author’s concept of pod-mounted weapons alongside two-man nacelle. points drive home the need for tactical control vehicles to have two men up. Let us for a moment ride with the historical APC-IFV trend towards more firepower and fewer men, and postulate an “M2EI”with a fire team of four rather than a squad of eight, and more punch up top - not too different from M3 in fact. And suppose this “M2E1” to mount a cannon, a developed form of grenade launcher (automatic light mortar), and, say, improved TOW. All these weapons systems differ from the tank gun in having no horizontal trunnion reaction, or a very limited one. So you can offset them wide, and even outrig them. This would allow you to put a tandem two-man nacelle (of the kind outlined above in figure 2b) on the center line of the “turret ring,” with outward-facing half-yokes to take the armaments (figure 7). This gives you a configuration which at least looks right. The commander/gunner of the two-man “gun tank” fights his vehicle from the hull with a trunnion-level VSSS, receiving tactical direction and surveillance backup from the IFV. With the dismountable element down to a fire team, ballpark figuring sug- I 1 I gests that this solution might also give you a vehicle pair based on M2/M3 automotive subsystems and compatable with CI IIBaircraft. Conclusion Having used a subjective approach to save space, let me close with a blatantly personal view. The longer you look and the more standoff you take, the more the future seems to lie with both “topless” and “bottomless” tanks. Technologically and structurally, bottomless tanks are already with us - in the shape of the Airborne Assault brigade based on HIND G and HIP (with HA VOC to come) on the one hand, and the Divison 86’s ACAB based on APACHE and BLACKHA WK (with LHX to come) on the other. Only new tactical thinking is needed to change the helicopter from a combat support weapon system into the mobility base of the fast maneuver force. The topless tank will come, perhaps first in the shape of an LMPG for alight mechanized force. But the armor user will insist, and will be right to insist, on having room at the top in the MBT until the acceptability of to-plessness is proven beyond a doubt.

BRIGADIER RICHARD E.

SIMPKIN had an extensive responsibility for armored vehicle development during his long career with the British Army, including the Chieftain, Scorpion, and Anglo-German MBT programs. In retirement, he manages a language consultancy and is the author of several books, including the recent I y- p u b I is hed Red Armour. 23