Friday, 9 October 2015

BMD-2

 
  


The BMD-2 is an airborne infantry fighting vehicle specially built for paradrop operations by the VDV - Russian airborne forces, first introduced in 1985. Its design is based on its predecessor, the BMD-1, which it is a modification of. Like the BMD-1, the BMD-2 belongs to a class of superlight IFVs designed with an emphasis on air transportability to increase the mechanized strength of airborne infantry.
  The BMD-2 never did replace the BMD-1, and it would seem that it was never intended to. The BMD-2's primary asset was its flexible 30mm autocannon, perfect for suppressive fire - and coupled with the high gun elevation made possible by the new turret and stabilizer system - a formidable threat to low-flying aircraft or infantry in elevated positions such as high rises or perhaps valley divides and mountains like in Afghanistan. However, there were things that the autocannon couldn't do that the 73mm cannon on the BMD-1 could. For instance, a single 73mm high-explosive shell is nearly 15 times more powerful than a 30mm equivalent, making it that much more useful for demolition work. Instead of replacing the BMD-1, the BMD-2 merely supplemented it, producing a synergy of sorts within the elite VDV - Russian airborne forces.



COMMANDER'S STATION


The commander of the BMD-2 is situated in the front left hull. He is typically the squad leader or platoon leader of the infantry squad attached to the BMD, so he disembarks along with the rest of the passengers, leaving only the gunner and driver to operate alone. While operating from within the vehicle, he takes charge of one of the two bow machine guns. Unlike his neighbour bow machine gunner, though, he is supplied with an extra fixed periscope for additional situational awareness. But still, being located in the hull means that he is in a less elevated position than he would be had he been placed in the turret like on the BMP-2, the BMD-2's land-borne cousin. This, and the non-optimum observation devices means that he mostly concentrates on coordinating tactical maneuvers through his radio or relaying orders to the rest of the crew, but he doesn't spot or designate targets for the gunner as a tank commander usually does. The driver has better forward vision, so the commander doesn't need to navigate for the driver either. The value of the periscopes would be that they give the commander a sense of his surroundings to better understand where the vehicle is in relation to landmarks, platoon vehicles, etc.

Originally, the commander's station in the first BMD-2 models was exactly identical to the one from the BMD-1. He is provided with a single fixed TNPO-160 periscope aimed to the left and a single TNPP-220 rotatable sighting periscope, slaved to his bow machine gun.


The TNPP-220 periscope can be rotated and elevated or depressed only as far as the bow machine gun's arc of traverse. The periscope itself has total range of vision of 20 degrees in the vertical plane and 76 degrees in the horizontal plane, not accounting for traversal.

With just two periscopes and limited coverage, the commander's ability to assess the tactical situation was very severely handicapped. Later on though, the commander's bow machine gun was removed, and the periscope sighting device was replaced with an MK-4 periscope in a fully rotatable protective housing for better vision.



The MK-4S periscope can be rotated by a full 360 degrees, and elevated by +18 degrees and depressed by -12 degrees. The periscope grants him a net range of vision of 18 degrees in the vertical plane and 47 degrees in the horizontal plane. Unfortunately, the placement still hasn't changed. His vision will still be easily interfered with by tall grass, large rocks, shrubbery and other terrain features, and his vision suffers tremendously if the vehicle is on the move over rough ground. The commander can bear down on the handle of the periscope for some impromptu stabilization to partially relieve the problem.


 




The TNPO-160 periscope is a simple fixed periscope. It provides a total range of vision of 28 degrees in the vertical plane and 78 degrees in the horizontal plane. All periscopes are heated through the RTS electric heating system to prevent fogging in cold weather conditions, and the MK-4S periscope housing is also heated to prevent it from being frozen in place.


COMMUNITCATIONS


The R-123 FM radio station is located directly in front of the commander, beside the bow machine gun.



Radio visible beside the driver's indicator panel

The R-123 radio had a frequency range of between 20 MHZ to 51.5 MHZ. It could be tuned to any frequency within those limits via a knob, or the commander could switch between four preset frequencies for communications within a platoon (which takes 3 seconds). It had a range of between 16km to 50km. The R-123 had a novel glass prism window at the top of the apparatus that displayed the operating frequency. An internal bulb illuminated a dial, imposing it onto the prism where it is displayed. The R-123 had an advanced modular design that enabled it to be repaired quickly by simply swapping out individual modules.

In 1984, the now-outdated R-123 radio was replaced by the R-173 radio, which had a frequency range of between 30 MHZ to 75.999MHZ. It has 10 preset frequencies. It had an electronic keypad for entering the desired frequency, and a digital display.

R-173

In the late 2000's, several hundred BMD-2s began a modernization program which included capital repairs and the installation of a new and advanced R-168-2UE-2 frequency-hopping encypted radio.

R168-25UE-2

The R-168 family of radios is now standard throughout the Russian ground forces, from infantry platoons to tank companies. It can produce frequency hops 100 times a second, and the data is encrypted as well.



GUNNER'S STATION


The gunner is the sole occupant of the one-man turret. Because of the increased internal volume of the bigger turret, his station is less cramped than the one in a BMD-1, but it is still quite small.

He has good all-round visibility from his station, which compensates for the lack of a commander in the turret. He is provided with four TNPO-160 periscopes, two aimed to the left and another two aimed to the right. Directly in front of him, of course, is where the gunsights are mounted.


As mentioned before, the TNPO-160 provides a total range of vision of 28 degrees in the vertical plane and 78 degrees in the horizontal plane.

He is provided with two sights; a combined day/night primary sight and a special high-elevation anti-aircraft sight.

Note the larger combined primary sight on the turret roof and the smaller high elevation anti-aircraft sight to the right

The weapons complex and fire control system is identical to the BMP-2. The weapons are controlled from a BU-25-2S control panel. The ammunition reserves for both the 2A42 cannon and the PKT coax are shown on a small digital display, along with the ammunition type currently selected for the 2A42, and the gunner switches the ammunition type for the 2A42 by flicking a toggle switch.




At the back of the turret, on the roof, there is a small ventilation port which can be opened and closed from inside by the gunner. The cover is attached to a threaded guide rod, which has a handle at the bottom. The gunner simply turns the handle to screw guide rod down, lowering the cover and sealing the port hole. A rubber gasket prevents the ingress of contaminated particles, but also prevents the egress of gunpowder fumes from firing the 30mm cannon.





SIGHTING COMPLEXES


The BMD-2 mounts two sighting units - a BPK-2-42-01 transplanted from the BPK-2-42 sight that the BMP-2 uses, and a PZU-8 anti-aircraft sight.


PZU-8 to the left, BPK-2-42-01 to the right


BPK-2-42-01



The BPK-2-42-01 combined passive/active universal sight is the gunner's primary sight. It is a very slightly modified variant of the BMP-2's BPK-2-42 sight, practically identical in all respects, including its compatibility with 3UBR8 'Kerner' APDS rounds. The sight is capable of passive light intensification or active imaging with the help of the L-2 Luna IR spotlight mounted co-axially to the gun and turret. The reticle may be illuminated by an internal light bulb to facilitate aiming at twilight hours if the night mode is not used. The nominal maximum range for identifying a tank-type target using active night vision is 800 meters.

The daytime sight channel has a fixed 6x magnification in the daytime channel and 5.5x in the nighttime channel, and a field of view of 10° in the daytime channel and the 6°40′ in the night channel.




The sight aperture is protected by a layer of  ballistic glass to protect it from bomb splinters, but there is an additional spring-loaded pane of ballistic glass that may be lowered for protection from small arms fire. However, the supplementary pane has worse image clarity and could make reconnaissance a little bit harder, so it is usually kept raised unless explicitly needed. The sight has a small wiper.

The sight is an unremarkable one, unfurnished with any accurate method of rangefinding. To do that, the gunner must rely on a simple stadiametric scale with a maximum measuring distance of 2.5 km. Once the range to the target has been determined, the gunner must manually enter the range data into the sight, which then prompts it to make the necessary adjustments to the position of the reticle, namely, by raising the reticle up and down. The gunner must then manually lay the gun on the target by lining up the target with the adjusted reticle (which would be lowered to compensate for distance, forcing the gunner to raise the gun so that the reticle meets the target). This crude system is more commonly found on tanks from the 50's and 60's.

Overall, the process was slow and clumsy. Users probably preferred to depend on battlesighting, and walking the rounds onto target. This means that the reticle is fixed at a predetermined range, usually about a kilometer or so, and the gunner makes corrections on the fly depending on whether the shell went high or low. This cannot be considered advanced by any criteria, but it is some consolation that contemporary IFVs such as the M2A1 Bradley had to depend on a similarly clumsy stadiametric choke reticle for range finding.



SOZh-M


Recently modernized BMD-2 models have swapped out the BPK sight for the new and slightly more sophisticated SOZh accompanied by a new PL-1-01 laser beamer replacing the old IR spotlight.




By emitting a pulsed laser beam, the PL-1-01 can also double as a laser rangefinder. A pulsed beam also reduces backscatter in poor weather conditions, thus allowing the gunner to see farther.

At this point, only a limited number of BMD-2s have been confirmed to be modernized thusly. One example is known to have ended up in East Ukraine. The "silent modernization" of BMD-2s is likely to be ongoing as part of the general military modernization plan.



PZU-8


The PZU-8 sight is mounted on the side of the turret. It performs primarily in the anti-aircraft role, thanks to its extremely high elevation of +85° and depression of -10°. Its very large field of view of 50° enables the gunner to effectively track fixed wing ground attack aircraft as well as fast-moving attack helicopters. The sight lacks independent stabilization. It is directly linked mechanically to the cannon, so that it elevates and depresses with it.

PZU-8 high-elevation auxiliary anti-aircraft sight. Notice the thickness of the steel protrusion protecting the sight along its length

Aperture
The sight elevates and depresses in line with the autocannon.



STABILIZERS

2E36-1



The BMD-2 is provided with two-plane stabilization in the form of the 2E36-1 fully electromechanical stabilizer, including the EDM-30 electric motor for turret traverse and the DGN-3 electric motor drive for weapons elevation.


 


The 2E36-1 stabilization system uses electric motors for both horizontal and vertical drives. The preclusion of any hydraulic drives saves space and increases the safety factor enormously; the lack of flammable hydraulic fluid being pumped at high pressure greatly reduces the chance of a catastrophic internal fire in the event of a turret perforation.

Vertical stabilizer motor and Horizontal stabilizer motor



The 2E36-1 stabilizer system has two modes of operation; automatic and semi-automatic. In the automatic mode, the stabilizer operates in the traditional sense, obeying prompts from the gunner and keeping the turret and cannon oriented with maximal accuracy at a point determined by the gunner. The semi-automatic mode, however, only meant for anti-aircraft use. Once the cannon is elevated more than +35 degrees, the stabilizer system shifts into semi-automatic on its own accord. In this mode, the stabilizer disconnects from the BPK-2-42-01 sight, which cannot be used to aim at angles of elevation of above +35 degrees, and interfaces with the PZU-8 anti-aircraft sight. The stabilizer then loses some of its precision, but gains speed. This is to help track and engage fast, highly maneuverable attack helicopters strafing at low altitudes and at closer ranges, where the relative speed of the aircraft in question is higher than if it was many hundreds of meters away. At longer distances, the elevation angle necessary to engage an aircraft at a certain altitude is less than if the aircraft is closer and the relative speed of the aircraft is also lower, so turret rotation speed is less important but more precision is required. In that case the gunner may continue to make use of the stabilizer in the automatic mode.


The stabilizer is good enough for the job, though the turret traverse speed has the potential to be much higher. Modernized BMD-2Ms (the variant with Kornet launchers) are apparently equipped with the latest 2E36-6 stabilizer complex. How much the new system differs from the old one is not known at this time.


Automatic Mode


Time for full turret rotation: 12 seconds

Maximum Traversal Speed: 30°/sec
Minimum Traversal Speed: 0.07°/sec

Maximum Elevation Speed: 30°/sec
Minimum Elevation Speed: 0.07°/sec


With a minimum traverse and elevation speed of 0.07 degrees per second, the average accuracy of stabilization would be able to achieve an aiming precision of no less than 1.24 mils, which is equivalent to 1.24 meters at 1 km. With the accuracy of the armament itself accounted for, that degree of accuracy would be more than enough to guarantee consistent hits on targets of the APC and IFV variety at typical combat ranges, though the degree of precision is still very lacking compared to Western technological equivalents of the time.


Semi-Automatic Mode


Time for full turret rotation: 10 seconds

Maximum Traversal Speed: 35°/sec
Minimum Traversal Speed: 0.1°/sec

Maximum Elevation Speed: 35°/sec
Minimum Elevation Speed: 0.1°/sec



At a cruising speed of 25 km/h to 35 km/h, the stabilizer is capable of maintaining its orientation at or close to its best performance. Drifting is noticeable at higher speeds. Needless to say, the precision increases linearly as the speed of the vehicle decreases.



ARMAMENT





  The existence of the BMD-2 revolves entirely upon its autocannon. The decision to mount it came about as a result of the discovery that the BMD-1's 73mm cannon was too slow to be effective against a purely infantry-based fighting force in Afghanistan, compounded by the insufficient gun elevation to deal with ambushes from the crests of valley roads, upon which supply convoys would often need to traverse. Additionally, the BMD-1 had no anti-air capability, which was a major issue because an air-dropped VDV regiment would have to depend entirely on MANPADS.  Its entire armament suite is located within the turret, composed of a single 2A42 autocannon and a PKT co-axial machine gun. The turret has provisions for mounting a 9K111 Fagot or 9K113 Konkurs ATGM on the roof to be fired from the exterior of the vehicle.


2A42



The 2A42 is a dual-feed autocannon chambered for the Soviet 30x165mm cartridge. It has a variable rate of fire of either 200 rounds per minute or 550 rounds per minute. However, it can go up to 800 rounds per minute once the cannon is heated up by a few seconds of firing on full auto. Its high rate of fire is invaluable during engagements with concentrations of infantry, or when attacking a well-fortified position, whereby extra demolition power may be necessary. In practice, the 2A42 is simply irreplaceable during engagements with stealthy adversaries. Even with thermal imaging sights, it may prove nigh impossible to spot and hit skilled and agile foot soldiers hidden in foliage and constantly on the move. Under such circumstances, the ability to saturate likely spots and areas of interest with high-explosive cannon shells is absolutely invaluable for preserving the vehicle itself as well act as in support of dismounted infantry. This was one of the reasons why the BMP-2 and BMD-2 was much more successful in Afghanistan and Chechnya than the BMP-1 and BMD-1.

The gun has +60 degrees of elevation and -5 degrees of depression. This gave the BMD-2 the ability to engage aircraft, as well as targets located in high rises and tall mountains, but the inability to adequately take advantage of reverse slopes remains constant. This is quite a blow to the overall survivability of the BMD-2, as its armour is far too thin to be able to sustain a head-on firefight, so it must always operate undercover. "Hull down" doesn't necessarily involve reverse slopes, of course. The BMD-2 can still take advantage of thick shrubbery, large rocks and other terrain features for concealment, but having one option denied to it is no small matter.




Maximum dispersion is 346.67mm at a distance of 100m. This figure can be expressed as 13.036 MOA (13.036 x 1.047 inches at 100 yards). This figure was calculated from an acceptance test video of the DVK-30 drop-in turret (link). By obtaining an MOA figure, which is an angular unit of dispersion, we can very easily find out what sort of dispersion we would get at different distances. At 1000 meters, the maximum dispersion (which I will define as the length of the distance between the two impacts that are furthest from each other), should be 3.467 meters, and all shots fire must invariably lie within that limit. Alternatively, a figure of ∼3 meters at a distance of 1000m can be expressed as a dispersion of 3 mils. This is congruent with claims floating around the internet of an accuracy of "2 - 4 mils". No doubt that this is pretty terrible performance for an autocannon firing at 200-300 rounds per minute, but that should be the maximum dispersion. The median dispersion should be much smaller. The second volley in the video shows a dispersion of just 8.12 MOA. That would be a dispersion of only 2.362 meters at a distance of 1000 m. Again, this fits into the "2 - 4 mils" claim neatly. The 2A42 cannon has a predisposition to create vertical shot groups. In both of the firing tests shown in the video, four rounds were arranged neatly in a vertical pattern, with one outlying shot skewing the results for the worst. As such, even though the cannon has an angular dispersion of 2 - 4 mils, 80% of the shots seem to tend to end up in an oval group of less than 2 meters.

This data should be valid for full caliber rounds like the 3BR6 and 3OF8. Subcaliber rounds like the 3BR8 will display superior accuracy and better consistency at all ranges, but the difference is only truly visible at longer ranges. 3BR8 APDS should have a maximum dispersion of 2 mils when fired from the 2A42, and just like with full caliber rounds, most of the shots will likely be located in an oval group less than 2 mils in size, as shot patterning depends more on the particular harmonic properties of the weapon system rather than the ammunition itself.





Although much less accurate than its immediate counterparts, the 2A42 cannon is more than capable of engaging pinpoint targets, though not as efficiently as the British RARDEN or American Mk44, which are more accurate by nearly two times. The RARDEN is accurate by virtue of special dampening and a very tame rate of fire, while the Mk44 is accurate thanks to a 69.4 kg barrel. If the gunner went for the RARDEN route and switched to semi-automatic to fire the cannon only about twice every second, it should be possible to approach (not meet) the same level of accuracy. Keeping in mind the fact that the ammunition capacity for the BMD-2 is quite limited, this is the only way the gunner can effectively eliminate armoured targets at long range while still having enough ammunition to complete the rest of the objective. In situations where accuracy may only have supplementary value, such as when engaging large concentrations of manpower, the 2A42 is at a clear advantage.


By virtue of its high rate of fire and powerful ammunition, the 2A42 is effective even against main battle tanks of the modern era, not to mention more lightly armoured vehicles. Live fire testing confirmed that the 2A42 is not only able to produce a 'mission kill' on main battle tanks, but also do it very rapidly, which is an invaluable attribute, especially for a vehicle as light as the BMD-2. In the space of a few seconds, the gunner can let off around 20 to 30 shots with a few short bursts at medium ranges and reliably guarantee the destruction or disablement of various exterior devices such as tracks, periscopes, sensors, weapons, or perhaps large exterior laser rangefinders and IR spotlights as found on 60's and 70's era tanks. After a few seconds of action, the BMD-2 can immediately disappear behind terrain under the cover of a smokescreen.


Recoil is managed by the double-baffle muzzle brake.




The autocannon is mounted slightly off to the right, which drives an unfortunate tendency for the turret to spin slightly to the right when the autocannon fires long bursts in full automatic. The effect is negligible at slower rates of fire, though, so this idiosyncrasy shouldn't affect accuracy too much when it matters. This problem possibly led to the use of the  low-recoil 2A72 cannon in the BPPU-1 turret for the BTR-80A and the BTR-82A instead of the 2A42.

The ammunition load of 300 rounds is stowed in separate conformal containers on the right side of the turret, the space on the left side being reserved for the gunner. 180 rounds of HEI/-T ammunition and 120 rounds AP-T and APDS-T ammunition are available. Under certain mission conditions where encounters with armoured vehicles are not expected, both containers can be loaded purely with HEI/-T ammunition. This was not uncommonly done in low intensity conflicts such as in Chechnya or Afghanistan.

The red container contains ready ammunition


Although the autocannon is undoubtedly extremely powerful, the small stock of ready ammunition for it severely limits the BMD-2's ability to conduct sustained firefights, and the lack of internal space makes stowing additional ammunition troublesome. Compared to the German Marder 1A+ series, for example; Those carry up to 1250 rounds of a much less lethal 20mm caliber, but that means that a Marder gunner has far more freedom in choosing his targets and a better ability to provide suppressive fire. Whether that suppressive fire actually has a chance of injuring anybody is a completely different question though. 20x139mm HEI ammunition for the Marder's Rh202 autocannon packs a measly 5.8g of Hexal, and the projectile itself weighs 125g. Compare that to the 3UOF8, which presides in an entirely different category altogether:





AMMUNITION







(3UOF8 HEI)

 


High-explosive incendiary shell intended for the destruction and neutralization of enemy combatants, helicopters, thin-skinned utility vehicles and light fortifications. In some cases, these shells may prove more potent than armour-piercing shells against heavily armoured targets since they are able to effectively able to damage and destroy sighting systems and other important components including periscopes, machine guns and fuel tanks. The destruction of these may already affirm the end of whatever mission the vehicle in question was on, without necessarily destroying the vehicle in question, although it is by no means a dependable method.


All Soviet autocannon shells manufactured after 1943 were filled with A-IX-2, but prior to that, generic explosive ammunition was filled with TNT and was split between two types: OZ (HE-I) and OF (HE-Frag). The best example is the 20mm ShVAK aircraft autocannon, which was supplied with a mix of OZ, OF and OFZ (HE-I-Frag) rounds. OZ shells were composed of a small HE filler with an incendiary pellet at the tip of the projectile, whereas OF rounds had a purely HE filler with fragmentation grooves, and OFZ was a hybrid of the two. The incendiary component was desirable for anti-aircraft purposes, whereas a higher explosive yield with fragmentation would be more optimal against ground targets. When A-IX-2 was invented in 1941, all subsequent autocannons intended for all varieties and combinations of roles (air-air, ground-air, etc) were supplied only with general purpose HE-I shells incorporating A-IX-2, which had the best of both worlds. 


The A-670M PD (point detonating) nose fuze is used. It will self-destruct after the shell has travelled approximately 4000 meters or so, depending on the strength of head and tail winds. For the 3OF8, the time to self destruct is 9 seconds. For the 3OR6, it is 14 seconds. The A-670M fuze intrudes 30mm into the shell, and protrudes 39mm beyond it. The fuze weighs 49 g. The fuze is armed by centrifugal forces 20 m to 100 m away from the muzzle (no less than 20 m). The fuze is of the superquick type, with an initiation delay of 0.002 and 0.004 seconds, or 2 to 4 milliseconds.

  

Cartridge weight: 842 g
Projectile weight: 390 g

Muzzle velocity: 960m/s
Guaranteed Kill area: 5.95sq.m (Blast and fragmentation)
Lethal radius: ~5m (Fragmentation)
Casualty radius: ~12m

Explosive mass: 49 g
Explosive filling: A-IX-2 (Phlegmatized RDX + Aluminium powder) (Aluminium is pyrophoric. Detonation produces incendiary effects, increasing the chance of igniting or burning objects in its proximity)


Compared to the 3UOR6, this shell is more useful when dealing with obstructions like walls and sandbag fortifications due to its much higher explosive power. It is also far more effective against personnel, thanks to the mass of the projectile and the number of splinters it produces. If compared to the American 25mm M792, the 3OF8 projectile weighs 2.1 times more, and it contains 1.53 times more explosives, despite a seemingly small increase of only 5mm, or 20% in diameter. 3UOF8 is in fact nominally more powerful than both the Oerlikon 30x170mm HEI-SD, which weighs in at 360g with a 40g charge of Hexal P30, and the American 30x173mm Mk266, which weighs 362g and contains about the same mass of explosive charge.

Without a doubt, 3UOF8 can reliably guarantee the destruction of armoured attack helicopters thanks to its large explosive punch, and the shell has a large lethal radius on soft skin targets thanks chiefly to the spray of more than 1000 splinters and fragments of various sizes and weights that the shell produces. Speaking of the quantity of fragmentation, it needs to be mentioned that we do not actually know how many fragments 3OF8 produces and the mass distribution of these fragments. According to Jane's Ammunition Handbook, the Oerlikon 30x170mm HEI-SD produces "an average of 1133 splinters and fragments, of which less than 0.05 g is dust". It would be reasonable to assume that 3OF8 is also somewhere in that range.


The shells are loaded in a 4:1 ratio of 3UOF8 to 3UOR6.


3UOR6 (HEI-T)

  


Tracered high-explosive incendiary fragmentation shell intended for engaging personnel in the open and behind cover. Small explosive charge makes this shell generally less suitable against the targets which the 3OF8 is used against. To compensate for the lack of explosive power, the shell relies mainly on the fragments it produces.

The A-670M nose fuze is used, like the 3UOF8. It will self destruct after 14 seconds.


Cartridge weight: 835 g
Projectile weight: 388 g

Muzzle velocity: 960m/s
Guaranteed Kill area: 1.4sq.m (Blast and fragmentation)
Lethal radius: ~3m (Fragmentation)
Casualty radius: ~12m

Explosive mass: 11.5 g
Explosive filling: A-IX-2 (Phlegmatized RDX + Aluminium filings) (Aluminium is pyrophoric. Detonation produces incendiary effects, increasing the chance of igniting or burning objects in its proximity)

Tracer burn time: >9 seconds


Although this shell has a mere 23% the amount of explosives contained in the 3OF8, it is encased with the same mass of steel, which somewhat compensates for that fact. Since a sizable portion of the shell's mass is composed of the tracer element, the 3UOR6 shell tends to undershoot the constant-mass 3OF8. This is especially noticeable at longer distances. 3OR6 shells have a smaller explosive charge than 30x170mm RARDEN HE-I-T shells, which weigh 360 grams and pack 20 grams of Hexal. This is due to the need for a larger and longer burning tracer element since 3OR6 travels at a lower velocity.

This shell is always loaded with the 3UOF8 in ratio of 1:4, being its tracered counterpart.


 3UBR6, 3UBR10(?) (AP-T)

  

Armour-piercing shell for the sole purpose of engaging armoured targets. This shell can be depended upon when engaging most IFVs and APCs, but not examples of the current generation. It is also capable of disabling some tanks when attacking from the flanks or the rear. From a technological standpoint, it is equivalent to solid shot APBC shells for anti-tank guns of WW2 vintage. This is actually quite convenient for us, because we know the main parameters of the shell, so we can easily find out its armour penetration using Peter Samsonov's penetration calculator with decent accuracy (link).


Cartridge mass: 856 g
Projectile mass: 400 g
Chamber pressure: 353-360 MPa

Muzzle velocity: 970 m/s
Core: High-hardness tool steel (60KhNM ?), 600 BHN, blunt tip


Penetration, RHA (60 degrees):
700m = 20mm
1500m = 16mm


(Official values)


Penetration, RHA (60 degrees):
500 m = 22mm
1000 m = 18mm
1500 m = 14mm

(Bulgarian copy)

Penetration, RHA (0 degrees)

0m = 48mm (Extrapolated)
700m = 43mm (Extrapolated)
1500m = 39mm (Extrapolated)


(Surmised values)

Tracer burn time: >3.5 seconds



The steel core in 3BR6 has a perfectly decent L/D ratio of 4.25, but its blunt tip lets it down. The lack of an armour piercing cap is a liability if the target plate is heavily sloped or preceded by spaced armour, despite the fact that 3BR6 uses very hard, high quality tool steel.


Due to its mediocre properties, its performance on light armour is rather modest, although it is certain that it is fully capable of perforating the armour of lightly armoured APCs such as the American M113, German Luchs, French VAB, or perhaps the generally light armour of scout cars and other armoured cars, while some modern vehicles like the Stryker and LAV III still prove totally vulnerable, being no better armoured than their tracked peers from the 60's and 70's. It is capable of handily defeating older IFVs like the Marder 1A2 and M2A1 Bradley from the front at ranges in excess of 1500 m, but against the latest IFVs or IFVs specifically beefed up against it like the M2A2 Bradley and Marder 1A3, the 3UBR6 shell is, for the most part, less useful than HEI shells. Furthermore, composite armour kits such as MEXAS can be fitted to many older vehicles, severely limiting the usefulness of 3BR6 even against outdated APCs.

It quite interesting to note that this shell should be able to perforate the side armour of some tanks of its time, particularly at close ranges. The AMX 30, Leopard 1 and Chieftain are three such unfortunate examples. Legacy tanks like the Centurion are highly vulnerable as well. However, achieving this feat does require the BMD-2 to be set up in an ambush position with opportunities to attack the flanks of the aforementioned tanks at a perpendicular angle.

There is some news that new ammunition incorporating plastic driving bands has been put into service in the Russian army. 3UBR10 matches this description, but its status remains largely unknown at the moment. The only difference between 3UBR6 and 3UBR10 is the replacement of the copper driving band with two nylon ones. You can see such driving bands here (link). Copper driving bands on a normal pressure round like 3UOF8 and 3UBR6 is equal to 1 EFC (Effective Full Charge). The 3UBR10 round is apparently 3 times less harsh on the barrel.



3UBR8 (APDS-T)

  

Greatly improved armour-piercing shell with a plastic discarding sabot with an aluminium plug, providing more opportunities to destroy armoured targets. Its properties are superior to the 3BR6 by a wide margin in all respects, including accuracy. A higher velocity and superior ballistic coefficient also enables the subcaliber tungsten alloy penetrator to travel with a flatter trajectory and to retain more of its energy at extended distances.

Cartridge weight: 765 g
Projectile weight: 304 g
Core weight: 222g

Muzzle velocity: 1120m/s
Core: Tungsten alloy

Penetration, RHA (60 degrees):
1000 m = 35mm
1500 m = 25mm
2000 m = 22mm

(Official values from Rosoboronexport and Kurganmashzavod)


Penetration, RHA (60 degrees):
100 m = 45mm
200 m = 40mm
500 m = 33mm
1000 m = 28mm
1500 m = 25mm
2000 m = 22mm


(Values from armyman.info)


Tracer burn time: >1.5 seconds



Although this shell travels at only 83.2% the velocity of its main counterpart, the M791, its core weighs 2.3 times more. Not only does this mean that the 3BR8 penetrator has twice the amount of kinetic energy, but the 3BR8 shell has a significant advantage in that it will retain more residual mass after perforating any given thickness of armour, making for superior after-armour lethality as a greater number of heavier fragments will be sprayed on the other side of the target armour plate after it is defeated.


The 3BR8 penetrator core is rather long, as you can see in the photo below.





   
Rosoboronexport claims that the 3BR8 shell can penetrate 25mm RHA angled at 60 degrees at 1500m while ATK claims that the M791 penetrates the same thickness of armour at 1300m. A presentation claims that M791 penetrates 44mm of RHA at 0 degrees at 2000 m, placing it on equal footing with 3BR8 at that range, however:

Knowing that the standards for certifying armour penetration differ between the East and the West, the discrepancy between the two rivals is actually even bigger. The Russians use V80 to certify their ammunition. The West uses V50. A V80 ballistic limit standard is where 80% of a set of shots perforate the target plate. Under this standard, perforation is where 75% of projectile mass ends up on the other side of the plate. The V50 ballistic limit standard is where 50% of a set of shots perforates the target plate, and 50% of projectile mass must end up on the other side of the plate.

The 3UBR8 shell is capable of defeating most modern IFVs, but with varying degrees of success. IFVs like the M2A2 Bradley, Warrior, Marder 1A3, and the like are vulnerable at short ranges at various parts of their frontal arc, but the most modern contenders like the Puma are probably fully immune except on their flanks, but only at very close range. However, this does not mean that 3BR8 is redundant. 3BR6 is largely incapable of disabling an armoured IFV from mid to long range, so using 3BR8 greatly improves the chances of achieving effective hits on the target.


A pyrotechnic charge is used to instantaneously cock the cannon and ready it for firing. However, if a pyrotechnic charge is not loaded, then the gunner can still manually cock the gun by repeatedly working a lever attached to the cannon receiver. The process is laborious and time consuming (due to the heavy springs necessary to withstand the tremendous recoil forces), but it does have its own advantages. Although such eccentricities would not be necessary in an electrically operated chaingun, a chaingun requires external power to fire. If the power source was interrupted, a chaingun would be rendered useless. Due to its gas-powered nature, the 2A42 can still be fired with the BMD-2 operating in "degraded mode" - knocked out engine and no battery power, all operations reverted to manual control.


SECONDARY





A PKT machine gun is mounted on the turret as a co-axial weapon, mainly for use in situations where the autocannon might be unnecessary or maybe 'overkill'. The 7.62x54mm ammunition used is not powerful enough to prove to be meaningful in any large capacity against entrenched manpower, or infantry behind masonry, but it is a viable means of providing suppressive fire. Ammunition is supplied in 250-round belts stored in individual boxes.



BOW MACHINE GUNS



Two more PKB machine guns are mounted on either side of the forward hull to be used by the two passengers seated on either side of the driver. Late model BMD-2s had the port side bow machine gun removed to free up more space for the commander to perform his other duties (manning the radio station, observing, etc). The unused machine gun port would be covered with an armoured plug.




The PKB machine gun was a modified PK machine gun with removable spade grips and modified trigger. The the rotating TNPP-220 periscope directly in front of the bow gunner(s) is mechanically slaved to the machine gun port. This meant that wherever the machine gun was pointed, the periscope would accurately face the same direction. Elevation as well as horizontal traverse were both fully accounted for. The bow gunner would aim using a small scope on the right side of the TNPP-220 periscope, visible below.




The reticle is the eyepiece for a small internal 1.5x scope.


The two connecting rods moved the periscope side to side, or levered them to rotate it up or down


The innovative aiming mechanism of the BMD-1 was later carried over to the BMD-2.

Ammunition for the PKBs is supplied in 250-round belts in individual boxes. Although the aiming system is somewhat rudimentary from an technical point of view, it was quite useful and certainly very novel. The spade grips and periscope combination probably allowed the bow gunner to hold the machine gun somewhat steady and provide decent suppressive fire, which is impressive given that firing from within a vehicle on the move has never been easy. In some vehicles, the machine gunner has no way of actually aiming. In vehicles like the Bradley, for instance, passenger machine gunners had to estimate the point of impact by "walking fire", which is so highly inaccurate that it would probably be better not to open fire at all.

The ball turret for the machine gun is heated through the RTC heater system to prevent it from freezing in place in cold weather condition. The mounting cradle for the PKT machine gun is seen below:


The periscope-to-machine gun connection has been dismantled in this example

Additionally, there are two firing ports on either side of the hull.

Firing port on the starboard hull
Firing port on the rear exit hatch

The firing ports can fit any type of rifle.



TERTIARY






Like the BMD-1P preceding it, the BMD-2 features a small protruding post on the roof of the turret, on which the 9K111 Fagot or 9K113 Konkurs ATGM systems may be mounted. The BMD-2 was issued with 9P135 Konkurs missile launchers, which were backwards compatible with Fagot missiles.



It must be said outright that one of the biggest failings of the BMD-2 lies in the fact that this rooftop ATGM may only be fired by either a dismounted passenger manning it from behind the turret, or by the gunner, who must open his hatch. The whole process from aiming and firing the ATGM to guiding it to its target may take as much as 20 seconds, exposing the user to return fire all the while. Although the operator (usually the gunner) may not have much to fear from bullets coming from the front, as his 6mm-thick hatch offers some protection, he would be in danger from overhead threats like airbursting mortar shells and bomb splinters from all around him.

As mentioned earlier, the missile launcher itself is the standard 9P135 launch-and-control unit, sans tripod. The launcher is placed very high up relative to the turret, far above even the gunsights. A cunning crew could take advantage of this and park their BMD-2 behind a hill, exposing only the missile launcher. After hitting the target, the variable height suspension may be lowered to conceal the launcher for a reload, and raised for another shot.

Another distinct, if questionable advantage to this setup is that the missile launcher can be dismounted and used by the crew when fighting on foot, if perhaps the vehicle is disabled. This means that even if they are forced to abandon ship, the crew still has heavy weapons on hand and still can repel an attack, and perhaps even live to put the launcher back on its pedestal.



Both the Fagot and Konkurs missiles are wire-guided, utilizing an infrared bulb at the rear end of the rocket for the launcher to track, and both missiles are launched via a two-staged propulsion system. The first stage is a squib cartridge in the rear of the container which generates high-pressure gas that propels the missile out of the tube. Once the missile has cleared some distance, the rocket motor activates and sustains the missile's flight up until it has reached its target. The high magnification power of 10x offered by the 9P135 launcher enables the gunner to use the long range of the missile to its full extent.

Like with the BMP-2, the high placement of the missile launcher plus the height adjustment feature of the BMD-2 presents some unique tactical opportunities. For example, it is possible for the BMD-2 to be placed in complete defilade with the hull and turret behind a hill, rock or other type of cover or concealment, and have the ATGM fired over it. The vehicle can adapt to a variety of such pieces of cover expressly due to its height adjustment feature.

There can be a total of 3 missiles stored behind the gunner's seat. Reloading the missile launcher is slow and laborious due to the rather cramped nature of the turret, but the fact that the missiles are stowed inside the turret itself and not in the hull simplifies matters considerably. The average rate of fire should be around 2 rounds per minute with both the Fagot and Konkurs.


9K111-2 Fagot


Although not usually issued along with the BMD-2, the launcher is compatible with this missile.

Weight of missile in container: 13kg

Minimum range: 70m
Maximum range: 2000m

Penetration: 400mm RHA


9K111-M Faktoria


Improved Fagot missile with upgraded sustainer motor and shaped charge warhead.


Weight of missile in container: 12.9kg

Muzzle Velocity:
Sustained Velocity: 186 m/s

Minimum range: 75m
Maximum range: 2500m

Penetration: 460mm RHA


9K113 Konkurs




By the time of the BMD-2's introduction, the Konkurs was the standard vehicle-based ATGM system. It can be considered an older brother to the Fagot, possessing a larger warhead and boasting a doubled flight range, but also much heavier, which made it unsuitable for manpacking. Nevertheless, the launcher was designed to be backwards compatible with the Fagot missile so that in case there was a shortage of Konkurs missiles and an excess of Fagot missiles, the BMD-2 could still operate with some anti-tank capabilities intact. Conversely, the launcher could then be dismounted and used on the ground if necessary.

The warhead had a rounded cuboid wave shaper. The large size of the stabilizing fins creates a lot of drag, which is quite inefficient during flight.

Weight of missile in container: 25.16kg

Muzzle Velocity: 80 m/s
Sustained Velocity: 200 m/s

Missile Diameter: 170mm
Warhead Diameter: 135mm
Shaped Charge Cone Diameter: 102mm

Minimum Range: 75m
Maximum Range: 4000m

Penetration: 600mm RHA



9K113-M Konkurs-M


Improved Konkurs missile in a tandem warhead configuration, with more powerful primary warhead.


Weight of missile in container: 25.16kg

Muzzle Velocity: 80 m/s
Sustained Velocity: 200 m/s

Missile Diameter: 170mm
Warhead Diameter: 135mm
Shaped Charge Cone Diameter: 102mm

Minimum Range: 75m
Maximum Range: 4000m

Penetration:
750mm RHA (Behind ERA)
~800mm RHA (Without ERA)



Because of the enormous weight of the missile, reloading the launcher on the turret roof is not an easy task, to put it mildly. The average rate of fire should be around 2 shots per minute, assuming that the vehicle is stationary. In reality though, the BMD-2 is far too lightly armoured to risk getting hit by return fire, so the most common scenario would be a shoot-and-scoot scheme.


Although old, the Konkurs ATGM is still very effective. Video evidence has shown that either it or the Fagot (but probably the Konkurs) is wholly capable of defeating the side turret armour array of an Iraqi (or Saudi) M1A1 SA Abrams tank, therefore justifying the inference that either two are also capable of defeating the side turret armour of any existing modern tank as well, as long as there is no ERA kit in the way. Even then, that will not be a problem for the 9M113M Konkurs with a tandem warhead. Since TUSK is primarily meant for urban combat and its weight makes traversing muddy terrain more difficult, it should be expected that the Fagot and Konkurs will still be very relevant on the Central and Eastern European battlefield.



PROTECTION



The aluminium hull of the BMD-2 is carried over from the BMD-1, and the turret is made of steel, just like with its predecessor. The vehicle is very light, but that is not to say that the vehicle has distinguishably poor protection per se; Although the BMD-2 is much lighter than most other IFVs, it is also much, much smaller than most other IFVs, which means that it retains armour density roughly equal to that of a volumetrically larger and correspondingly heavier vehicle.

The hull is made of aluminium alloy, while the turret is made of steel. The frontal arc can withstand .50 caliber machine gun fire at reasonable distances, and the sides can resist 7.62mm machine gun fire with good guarantees - slightly worse than the non-airborne BMP-2 nominally, but superior to the M113, a similarly aluminium-cladded armour personnel carrier.


The aluminium used for the BMD-2 is alloy ABT-101, same as the BMD-1. According to several research papers written on the subject, the effectiveness of the best aluminium armour and aluminium laminate armours may reach up to 50% of steel by thickness, but non-armour grade aluminium alloys are typically only around 40% as effective (or less). An example of this would be 5083 alloy, used in the M113. 5083 alloy was only 34% as effective as steel for the same thickness.

ABT-101 was specially developed to be used as armour, and because of that, it had more suitable properties, giving it significantly better performance - up to 45% as effective as steel armour per thickness. However, because of the generally worse hardness of aluminium, it is much less capable of deflecting ballistic threats than typical armour-grade steel for the same thickness, so aluminium armour does not gain as much protection from angling as hard, armour-grade steel would. ABT-101 has a hardness of approximately 145 BHN, harder than mild steel and harder than 7039 aluminium alloy, which is known to be used in American designs like the M551 Sheridan and M2 Bradley, and much, much harder than the 5083 alloy, which had a hardness of just 75 BHN. However, all of these aluminium alloys are much softer than typical RHA steel, which typically ranges from 220 BHN to 300 BHN in hardness. The comparatively greater hardness affords the BMD-2 better performance against bullets of all types compared to foreign aluminium armour, and certainly significantly greater potential as sloped armour.


The turret is made from welded hard steel plates. The front is uniformly 22mm thick, sloped at 37 degrees. This is enough for .50 caliber AP bullets at point blank range, but not much more. The rear of the turret is around 10mm thick.


The frontal hull aspect draws a great deal of its protection value from its pike-nosed geometry and heavy angling, best seen here:




The upper glacis is angled at 75 degrees on the vertical axis, and the lower glacis at 47 degrees. There is also an additional 20 degrees of horizontal sloping for both upper and lower glaces. The upper glacis is 15mm thick while the lower glacis is 32mm thick. The line of sight (LOS) thickness of the upper glacis and lower glacis is therefore 61.7mm and 50mm respectively, but this is not as important as the large compound angle, which makes it very difficult for an uncapped ogive penetrator (as found in a typical Spitzer bullet) to not ricochet immediately without so much as denting the armour.

The sides are quite thin. The upper side plate is only 23mm thick, and the lower side plate is thinner at just 20mm. The roof of the hull is not enough to resist large caliber airbursting artillery shells, and the floor is so thin that it would definitely rupture from the blast of an average sized anti-tank mine detonating underneath the track.





To better appreciate the protection offered by such a thickness of aluminium, we can take a look at the phase diagram below. This phase diagram, taken from "Armour: Materials, Theory, and Design", illustrates the huge importance of slope. As you can see, the test used a 6.35 mm aluminium alloy plate, no doubt 5083 aluminium, as a target, and 6.35 mm-diameter bullets, no doubt solid steel ones, as projectiles. A 6.35 mm projectile like this is representative of the steel AP core of the average 7.62mm rifle bullet. The AP core of a 7.62x54mm Russian B-32 bullet, for instance, has a diameter of 6.1 mm, with a weight of 5.39 grams. It has a muzzle velocity of 830 m/s. The AP core of a 30-06 M2 bullet has a diameter of 6.2 mm, and weighs 5.17 grams. It has a muzzle velocity of 855 m/s. AP core of a 7.62x51mm M61 bullet has a diameter of 6.3 mm, and weighs 3.8 grams. It has a muzzle velocity of 838 m/s.




As you can see in the diagram, there is no hope for the aluminium plate to shrug off the bullet unless it is sloped at an angle of at least 65 degrees, whereupon the bullet will shatter against the plate and ricochet off harmlessly. Unfortunately, there is no place on the BMD-2 that is only 6.35mm thick, and it does not use 5083 aluminium alloy, so we cannot directly apply the findings above to the armour scheme on the vehicle. But still, it is an interesting example of the importance of obliquity, as it demonstrates that a 75 BHN metal of rather low strength is capable of deflecting a bullet that matches it in thickness if slope is applied liberally. The test might or might not be scalable, but if it is, and we substitute the 7.62mm AP bullet with a .50 cal or 12.7mm one, we see that the upper glacis of the BMD-2 with its thickness of 15mm and slope of 75 degrees (plus 20 horizontal slope) is more than enough to deflect heavy machine gun fire at point blank range. The lower glacis should perform better, as it is much thicker, and the compound angle of the slope adds up to more than 65 degrees. It is also good to keep in mind that information on 5083 and 7039 alloys seem to indicate that they are more efficient against 12.7mm bullets than 7.62mm bullets.


NII Stali has released some documentation (read: promotional material) on the ballistic performance tests of ABT-101 alloy quite extensively, and some of that material is in my possession. Take a look at the graph below, titled "Comparative Characteristics of Aluminium Alloy Armour of the U.S.A and Russia".

Legend: Bullet B-32 (Russian), Caliber: 7.62, 12.7

y-axis: Velocity (V)
x-axis: Armour thickness/Bullet caliber ratio



For reference: a 12.7mm B-32 bullet has a muzzle velocity of around 850 m/s when fired out of an NSV heavy machine gun, and a 7.62mm B-32 bullet has a muzzle velocity of 855 m/s when fired out of a PKM general purpose machine gun.

Reading this graph, it appears that to stop a 7.62mm B-32 armour piercing bullet at a distance of 100 meters or so, it would take an ABT-101 armour plate with a thickness of around 4.2 calibers, which will be exactly 32mm. To stop the same bullet at a distance of 460 meters, it would take a plate with a thickness of 3 calibers, which will be 22.9mm - the same as the thickness of the upper side plate of a BMD-2. Therefore, there would need to be at least 500 meters of distance between a BMD-2 and a dude with a FAL for the BMD-2 to begin to be proof against it. The 23mm of ABT-101 is equivalent to 10.35mm of rolled steel armour.

This information is not entirely consistent with other research materials concerning 7039 aluminium alloy armour. Further research is needed to reconcile all available information. However, this information aligns perfectly with the results of ballistic tests conducted on the BMD-1 during its infancy.





Ballistic tests were conducted on the BMD-1 throughout its developmental cycle, and continued even after it formally entered service. During tests undertaken from October 25 to December 25 in 1972, the BMD-1 was subjected to more ballistic tests involving weapons ranging from 7.62x39mm light ball bullets to 23mm hardened steel core armour piercing rounds. The black and white photos above and below show the state of the BMD-1 after the tests. These photos were taken from the December issue of Tekhnika i Vooruzhenie 2009.


 


The upper part of the side hull is proofed against 7.62x39mm BZ rounds at a distance of 125 meters, while the lower part is proofed at 175 meters. The front hull and turret are totally immune to 23mm BZT rounds (API-T) from a distance of 500 meters when shot from the direct front.


Ammunition Angle of immunity (°), immunity arc (°)
12.7x108mm B-32 (AP, hardened steel core) 35, 70
7.62x54mm B-32 (AP, hardened steel core) 53, 106
7.62x54mm Light Ball (FMJ, mild steel core) 70, 140
7.62x39mm BZ (AP-I, hardened steel core incendiary) 68, 136


During the course of the testing, it was discovered that the amount of protection afforded to the radiator packs (the two humps on either side, above the rectangular exhaust ports) from gunfire was unsatisfactory. Surprisingly, the engine cover was heavy enough to deflect 7.62x39mm BZ rounds fired from a distance of 125 meters.





Contrary to the Wikipedia-perpetuated urban legend of the BMD-2 and BMD-1 having "cast magnesium armour" that "burned fiercely when hit by an RPG", neither the BMD-2 or the BMD-1 used cast magnesium armour. ABT-101 is an aluminium alloy, and both BMDs are built from welded plates. ABT-101 is an Al-Zn-Mg alloy containing 91% aluminium, while the other 9% is composed of zinc and magnesium, but mostly zinc. If you heated it long enough with a hot enough flame, it will burn, but it won't catch fire spontaneously if it gets hit.





Generally speaking, the BMD-2 has insufficient all-round protection from machine gun fire, but it has disproportionately good protection across the front. Its protection from mortar splinters is fine. The hull can handle fragments and splinters from larger artillery shells (150mm-type) periodically, but only when there is some distance between it and the explosion.


The BMD-2 is hopeless against any form of autocannon fire at any range within reason, but notable exceptions would be cannons firing the rather anemic 20x102mm cartridge, particularly the common M197 gattling gun as mounted on helicopters like the AH-1 Cobra, or perhaps the M61 Vulcan fired from an M163 SPAAG or the M167 VADS. At distances of about a kilometer, the BMD-2 should have sufficient protection to grant it a reasonable degree of immunity from multiple hits across the frontal arc, and even the side armour has a decent chance of holding up at not-to-long-distances. This would have severely diminished the merits of helicopter support (especially since the BMD-2 has a 30mm cannon good for shooting down helicopters) and seriously devalued 20mm anti-aircraft weapons in any other role except air defence.

Additionally, a certain degree of immunity was provided against 20x139mm AP-T shells, popularly used in autocannons mounted on scout cars as well as fixed emplacements like the widespread Rh202 twin autocannon mount. This would also mean that the BMD-2 is survivable even against much heavier IFVs like the Marder 1 at longer ranges.

However, the situation is drastically different today. The intolerably thin side armour is too vulnerable to the most modest small arms. Without any armour upgrades, the BMD-2 is too poorly armoured to be used in a front line capacity. The problem can be potentially remedied with an applique armour kit, as the BMD-2 is no longer required to not exceed 8 tons in weight thanks to the availability of heavy lift transport aircraft and heavy duty rocket parachute systems, but this has not been done in recent years for unknown reasons.


Additionally, the diminutive size of the BMD-2 contributes greatly to its overall survivability. With maximum ground clearance, the BMD-2 is negligibly taller than the average Soviet male combatant at 1.905m, but only 1.585m tall with minimal ground clearance. The photo below illustrates that neatly.




At its maximum, the BMD-2 is only slightly taller than many Western combatants, making it exceptionally difficult to score a hit at long distances. Attempting to visually identify a camouflaged BMD-2 from afar would be next to impossible, especially when plenty of shrubbery is present and the crew is properly taking advantage of terrain features with the help of the vehicle's variable ground clearance. Thus, although the armour of the BMD-2 is wholly insufficient against heavier anti-armour weapons, its survivability would still be quite high.

However, size no longer makes any difference in the present. Current generation autocannons like the new Rheinmetall Mk30-2/ABM and Bushmaster Mk44 are so accurate that they will have no trouble at all achieving a near-100% hit rate at long distances on the BMD-2, even while both are moving at high speeds, and modern thermal imaging sights will be able to see and track the BMD-2 as clear as day at any distance.




ERGONOMICS





There is very little space for passengers in the BMD-2. There are three seats immediately behind the turret basket for dismounts, arranged around the circumference of the turret. Two are located on either corners of the compartment and the center seat is located directly underneath the large exit hatch, but there is so little distance between the turret basket and the engine compartment partition that the dismount must sit sideways.

Port side passenger's seat
Center passenger's seat

The interior is very cramped in general. There is barely enough room for the squad to haul along additional equipment other than the standard RPG-16 or RPG-7D. The fender shelves (empty space above the tracks) can be used to stow a MANPADS launcher.

Each seat is provided with a periscope to grant the occupants some situational awareness. The two passengers seated on either side of the hull are given a TNPO-160 periscope each, which are aimed slightly forward. There is another MK-4 rotatable periscope mounted in the rear hatch, which allows excellent coverage of the vehicle's rear and flanks.

Ventilation for all occupants is provided by a single dome-shaped ventilator located on the starboard side of the hull, adjacent to the turret.



The ventilator sucks in air through a wire mesh-covered radial port. It has an internal filter for operation in highly dusty or chemically and biologically contaminated zones, and the filter additionally incorporates an integrated self-cleaning system, utilizing blasts of high pressure air to blow dust and other filtrates out through the evacuation port (protruding port on the dome, not covered by mesh, as seen above). This ventilator is responsible for creating an overpressure to prevent any such contaminants from entering the vehicle.




The ventilator has an electric heater installed for supplying the occupants with warm air.

There are two storage bins located on top of the engine deck. They are meant for tools and spare parts. Being placed where they are practically guarantees that they will be untouched during combat.





DRIVER-MECHANIC'S STATION



At the very front of the hull is the driver's station. The steering system is of a tiller-type, with dry friction clutches. The tillers also connected to a pulley system, which opens and closes the water jet covers depending on how far the tillers are pulled back. He has access to all the necessary driving-related controls as well as controls for all of the miscellaneous features of the vehicle, including interior heating, NBC activation, and the like. The instrument panel can be seen in the photo below. Note that the absolute maximum speed is 100 km/h.




The driver has very good driving visibility from his bank of three TNPO-160A periscopes. They are heated through the RTC system to prevent fogging.




The center periscope may be replaced with a binocular night vision periscope.




Or a TNP-370A extended periscope for when the vehicle is swimming.




The TNP-370A extended periscope has a total range of vision of 42 degrees in the horizontal plane, and 12 degrees in the vertical plane. The periscope allows the driver to peer over the trim vane and navigate in the water without assistance from the gunner, who might be busy bombarding targets on shore.


The BMD-2 has a single F-125 IR headlight on the starboard side and a single F-126 white light headlight on the port side.

The F-127 IR periscope is used exclusively in tandem with the binocular night vision periscope for nighttime driving. The view range of the periscope is completely insufficient for any real navigation, but it is good enough for road marches and less intense maneuvering. The IR filter cap may be removed to revert the IR headlight into a regular driving light if needed.


Starboard side driving light and of course, the horn



For convoy driving, the F-126 headlight/blackout light may be used. Blackout lights function by directing light forwards and downwards through small slits, minimizing the amount of light being transmitted off in other directions. This is to minimize the possibility of being seen, especially from afar. Because blackout lights only illuminate very small areas in front of the vehicle, the driver can't really see any further than a few meters. Depending on them for navigation is completely out of the question.





MOBILITY




Both the BMD-1 and the BMD-2 are powered by the low-profile 5D-20 V-shaped 6-cylinder diesel engine, located at the rear of the hull. It produces 240 hp at 2400 RPM. Originally, there were three methods to start the engine; electrically, pneumatically and combined. The pneumatic method involved using compressed air from a 10-liter compressed air tank to get the pistons moving, while the electric method required the use of the S-5 15 hp electric starter motor. The combined method is, obviously, a combination of the two. The combination method is most useful in cold weather. In 1973, the BMD-1 received the AK-150MKV air compressor. AK-150MKV was powered directly by the engine via a reduction gear. The introduction of this air compressor enabled the BMD to refill its 10-liter compressed air tank on the move, thus making it possible to rely entirely on the pneumatic starting system for every occasion. 

The BMD-1 is very light, just 6.7 tons empty. According to the manual, the BMD-1P weighs 6.7 tons empty, 7.2 tons with fuel and oil, and 7.38 tons fully loaded for combat. The power to weight ratio is 32.5 hp/ton when fully loaded, and the average ground pressure exerted is 7.1 psi.

The BMD-2 is significantly heavier at 8 tons empty, and 8.225 tons fully combat loaded. The power to weight ratio is 29.2 hp/ton when combat loaded, and over 30 hp/ton when not. This is slightly lower than the BMD-1, but still good for its class of vehicle.

Both the BMD-1 and BMD-2 have a maximum driving speed of 61 km/h on a highway, and an average speed of 30 to 50 km/h when travelling cross country. It readily accelerates, and the amount of torque generated lets the vehicle traverse rough terrain speedily.

The engine is liquid-cooled. The radiator is located to the left side of the engine compartment. The photo below shows the engine air intake.




Located immediately behind the engine is the transmission. The drive shaft that spins the engine air intake fan is the same shaft that connects to the gearbox.





The exhausts are located at the two rearmost corners of the hull. The radiators are located on the top of either side of the two "humps", above the exhaust ports, and above the fuel and oil tanks.

Take a look at the photo below. Notice the pipes from the manifolds of the engine leading out towards the exhausts.




As mentioned before, the radiators are protected by armoured louvers which can be remotely shut by the driver from his station. They are supposed to provide protection from airbursting shells, small arms fire from above and flame attacks, but seeing how thin the roof of the hull of the vehicle is, there is no real point in taking this step.

There is an integrated electric heater to heat up air before it enters the engine, to facilitate starting in cold weather.




The port side "hump" in front of the radiator holds essential fluids for the engine, such as lubricant, coolant and transmission oil. The photo below shows the ubiquitous armoured plugs that allow access to these fluids.




The fuel, lubricant and oil system can be seen in the diagram below.





The BMD-2 can climb a vertical slope of 32 degrees, traverse a side slope of 18 degrees, and overcome a vertical obstacle 0.7m in height. It is able to cross trenches 2.5m in width, but is is capable of leaping over gaps as wide as 4m or more by running on a ramp or hitting a bump just before crossing. The BMD-2 can this do effortlessly and almost without risk thanks to its ability to get itself up to a very high speed.


The BMD-2 has five solid die-cast aluminium roadwheels with rubber rims on either side. Lightweight hollow roadwheels like the type used in the BMP-1 and BMP-2 helped increase buoyancy, but they would not have been able to withstand the force of an airdrop landing, thus necessitating roadwheels exclusive to the BMD-1 and BMD-2. Despite this, the lightness of the chassis and the relative softness of aluminium compared to steel means that the overall resilience of the suspension to high dynamic loads and hard impacts is quite low. A collision with a tree will result in a ripped-off idler wheel and roadwheel.





The BMD-2 has a ground pressure of 7.1 psi fully loaded, which is rather high despite its low weight. This is because of its thin tracks, which are also unfortunately somewhat fragile. The thinness of the tracks means that there is less frictional force with the ground (not the same as traction) when turning. This gives it superb agility over paved roads as well as dirt ones, but the BMD-2 suffers when crossing swampy ground. In which case, it must make good use of the eponymous log. The BMD-2's performance is snowy terrain is excellent. The relatively high ground pressure enables the tracks to penetrate snow and reach the frozen soil underneath, thus granting the BMD-2 good traction.

The innovative hydropneumatic suspension on the BMD-2 carries over from the BMD-1. It is very compact. The unique suspension gives the BMD-2 the ability to adjust ground clearance on-the-fly. The ground clearance can be adjusted to either 0.1m or 0.45m, or anything in between. The default setting for driving is 0.42m. The lowest setting is used to properly load the BMD-2 onto a plane before an air drop to minimize impulsive forces on the suspension in order to prevent damage to the suspension upon landing, but it is also useful for reducing the total height of the vehicle to let it fit better into the confines of a cargo hold. This is contrary to counterparts like the Bradley, which must be lashed to a loading pallet with tremendous force to compress the torsion bar suspension so that the hull would be as low as possible for loading. With the BMD-2, all this is done at the flick of a switch by the driver. The vehicle may be driven in any configuration. Fully lowered, the roadwheels have almost no room to travel and therefore cannot absorb shocks from terrain irregularities.


Lowered, not tensioned
Raised

The hydropneumatic suspension system uses a pneumatic cylinder as a spring. Adjusting the height of the roadwheels is done by adjusting the pressure in the pneumatic cylinders. The pneumatic cylinder is placed above the hydraulic piston, which is connected to the roadwheel. The pneumatic cylinder has a manual release valve to relieve pressure (at the top of the cylinder, seen below), and air is ported to the chamber behind the hydraulic piston, pushing it or pulling it depending on whether the air in the pneumatic cylinder is pressurized or depressurized. To keep the roadwheel in position, the pressure must be constant. The system is self contained - the pneumatic cylinder contains all the air necessary. Air is distributed by valve banks located under the seats of the port side and starboard side passenger seats in the passenger space.



The hydropneumatic mechanism is visible in the photo above. It is currently disconnected from roadwheel arm (you can even see the locking pin on the floor). The BMD in the photo must be resting on the belly of the hull, judging from the position of the roadwheel arm.

Air for the pneumatic springs is supplied by an air compressor powered by the engine. It is located directly forward of the engine, behind the partition between the engine compartment with the passenger compartment.





And of course, the idler wheel and drive sprocket can be adjusted for track tension as well. This is done by a hydraulic piston.





The tracks on the BMD-1 are of the single pin variety with rectangular inner guide horns, as you can see below:




The BMD-1P introduced new tracks with "dog bone" guide horns. These tracks are thicker and sturdier, but also slightly heavier. They are harder to throw and are just a bit better overall.



The new BMD-1P tracks carried over to the BMD-2.



FUEL



The BMD-2 holds 280 liters of fuel at the rear of the hull on either side of the engine compartment, giving it a cruising range of 500km on a highway on internal fuel alone. Because of their placement, the fuel tank will never pose a threat to the crew or the vehicle itself. From the rear, they are hidden by the radiator and exhaust unit, completely precluding the possibility of them getting hit. If the side hull was penetrated, fuel would simply leak out harmlessly, away from the exit hatch at the engine deck.


WATER OBSTACLES



The BMD-2 is fully amphibious, and can readily enter and cross large bodies of water. But first, the driver must activate the electric bilge pumps (which throw water out of the interior if it is flooded), erect the wave breaker, and shut off the engine air intakes. All this is done automatically by flicking toggle switches.

Like the BMD-1, the BMD-2 is propelled by two waterjets (pictured) when in the water.




Water is sucked up through underbelly ports located at the very rear of the hull, as you can see:




To prevent water from sloshing up to the driver's hatch a trim vane must be erected. There is also a simple ribbed wave breaker attached to the hull glacis.




It is pushed up to the 'open' position by a small rod and crossbar assembly, pictured below:


Wave breaker and trim vane removed

Because the exhaust ports will be totally submerged when the BMD-2 enters water, the exhaust gasses are blown out by compressed air generated by the bilge pumps. The bilge pumps also work to throw water out of the hull through the same exhaust ports. This is done strongly enough to blow water straight up in the air.




When the vehicle exits water, the exhaust ports will spit any collected water back out with tremendous force as long as the bilge pumps are still on.



(The radiator is smoking, which never happens when driving on land).



The BMD-2 is heavier than the BMD-1, but uses the same hull, which means that it has a considerably worse buoyancy reserve.


STRATEGIC MOBILITY



 


The BMD-2 is rather famous for being an air-droppable "tank", and rightly so. It can be air-dropped directly into the battlefield by appropriate cargo planes such as the Il-76, from an altitude ranging from 2000m to just 500m. It is worth noting that if the transport plane is not flying at low altitudes, it will most certainly be detected and tracked by enemy radars, and so will the parachuting BMD. Although an air insertion is very quick, it is not clandestine.

Besides air drops into enemy territory, the light weight of the BMD-2 makes it very easy to transport in large quantities by plane.





Using the PRSM-925 retro rocket parachute system, the vehicle may be dropped with the entire crew plus passengers from an altitude of 500m to 1500m. The PRSM-925 rocket system needs only one large main parachute. It's primary purpose is to align the retro rocket and the suspended vehicle perfectly perpendicular to the ground, and its secondary purpose is to control the speed of descent, which is still very high. Because there's only one parachute, there is not much clutter that can entangle the vehicle on landing, and because the speed of descent is relatively high up until the retro rockets activate, the amount of time the BMD-2 is visible in the air is significantly reduced. Before being loaded onto a plane, the BMD-2 must loaded onto a shock absorbing pallet beforehand. This is to prevent the vehicle from sinking if it lands in marshy soil.




The rockets are activated by a contact probe deployed from underneath the pallet. They ensure that the rocket activates at the optimum altitude for the softest possible landing.




Alternatively, the RKMS-165 multi-parachute system may be employed:




It involves the use of a bouquet of 9 large primary parachutes, and instead of a rocket booster to soften the landing, a simple air cushion is used instead. Landing through this method is rougher, and is less suitable for a crewed landing. Additionally, the crew needs to remove several straps securing the hull to the air cushion before the vehicle can be put into action. This is far too time consuming for combat insertions, so this method is only used for delivering the BMD-2 to remote areas quickly where an airstrip or a suitable landing zone is not present, but immediate combat is not expected. Air transport is faster than rail transport, and much faster than having the vehicle driven by itself. Air dropped vehicles like the BMD-2 are often the only force multiplier that soldiers may have until heavier equipment can arrive, and that may take days.




Another option lies in the use of heavy transport helicopters. The BMD-2 may be carried the Mi-26 or Mi-10 in particular.


Two BMD-2s about to be loaded into an Mi-26

The BMD-2 may also be flown by a Mi-6, but only in an underslung configuration. Two BMD-2s may be transported internally per sortie in an Mi-26, or one in an underslung configuration. The Mi-10 may transport one BMD-2 attached to the fuselage.




References


http://mreadz.com/new/index.php?id=132817&pages=10

NII Stali Fact Sheet on Aluminium Armour

http://www.dishmodels.ru/wshow.htm?mode=P&vmode=T&p=261&id=4395&tp=w

http://vmk.tplants.com/ru/products/bmd2/

http://lzos.ru/en/index.php?option=com_content&task=view&id=72

http://lzos.ru/en/index.php?option=com_content&task=view&id=71

http://kbptula.ru/en/productions/small-arms-guns-grenade-launchers/guns-machine-guns/2a42

http://kubinkamuseum.ru/index.php?option=com_content&view=article&id=76&Itemid=274

https://books.google.com.my/books?id=BNvfNYW6yisC&pg=PA24&lpg=PA24&dq=bmp+squad+leader&source=bl&ots=epAOthRskO&sig=HcU2bjIyxVHBPzUhSHydf0fmiWE&hl=en&sa=X&redir_esc=y#v=onepage&q=bmp%20squad%20leader&f=false

http://www.wk2ammo.com/showthread.php?3203-20x139-shells-for-the-HS-820-(Oerlikon-KAD)-amp-Rh-202-gun

http://www.rheinmetall-defence.com/en/media/editor_media/rm_defence/publicrelations/pressemitteilungen/2013_1/2013_Rheinmetall_IDEX_Medium_Calibre_Ammunition.pdf

http://coollib.com/b/237493/read


Bibliography


Soviet Bloc Elite Forces By Steven J. Zaloga (unreliable)