CASR

Canadian
American
Strategic
Review

Blast  Resistant  Vehicles  –  CF Armoured Fighting Vehicles  –  October 2006 Blast-Resistant  Vehicles  For  Beginners  —  Distinguishing the 'Armoured' From  'Mine-' and 'Blast-Resistant' Vehicles Stephen Priestley, Researcher, Canadian American Strategic Review (CASR) Who are You Calling a ‘Jeep’?! –  CF’s RG-31 Nyala APV Passes the Acid Test On 26 September 2006, a  suicide bomber  attacked a Canadian convoy 2km from Kandahar Airfield. The bomber detonated a explosives-laden minivan while trying to ram an  RG-31 Nyala Armoured Patrol Vehicle. The result differed dramatically from earlier attacks on armoured G-wagons. Instead of charred wreckage, the blast- resistant Nyala limped home with little damage. Instead of  wounded  or dead, no-one was injured inside the APV. [1] Whether by bad planning or good luck, the suicide bomber  had chosen his target poorly. Immediately behind the Nyala APV in this returning supply convoy was a G-wagon light utility vehicle. Had that smaller vehicle been attacked, the outcome might well have been tragic. As it is, repair is needed but the APVs are vindicated. The RG-31 Nyala was designed to survive the blast from landmines. Some questioned whether  this concept  would also stand up to  roadside  or  vehicle–borne  improvised explosive devices. The  answer  was  given by an IED-damaged APV limping back into KAF on a flat tire, with smoke wafting from beneath its displaced hood and one crazed armour-glass window.  Not  the  first attack on an APV but it was a convincing test. [2] “In a Nut Shell” –  or  Differentiating ‘Armoured’ From Truly ‘Blast-Resistant’ Commentary on Canadian Forces vehicles in Afghanistan has tended  to focus on the weight of armour and size of vehicle. Both have some bearing – thicker armour offers more protection, larger vehicles can carry heavier plating. Missing from this equation is the form of the armour. For its weight, a LAV III offers reasonable pro- tection from IEDs. But, its thin armour has been shaped primarily to deflect shells. Like most modern armoured vehicles, the belly armour of a LAV is almost completely flat.  Belly armour was tested by Defence Research with industry participants –  first at Valcartier, then at Suffield. [3] As a result, a second, bolt- on belly panel (tested on an AVGP, right) was fitted. This bolt-on panel gives greater protection against penetration. This is important but a landmine or IED also generate so-called ‘blast waves’ or blast overpressure (BOP). With flat-bottomed vehicles, the blast effect can be amplified if an explosion occurs directly beneath. A blast wave striking the underside will  be ‘reflected’ back at the ground.  Before dissipating, that energy will be redirected at the vehicle (if the BOP from the initial explosion is strong enough to lift the vehicle, an assymetric, reflected blast wave may well topple the vehicle onto its side). In most cases, the weight and ground clearance of a LAV means that the vehicle will not  be ‘lifted’ by blast. The undersides of a LAV may be flat but it is also relatively smooth and  free from projections. This is in direct contrast  with a ‘soft-skinned’ vehicle like a G-wagon with its add-on armour.  Like a liquid wave, blast will curve around a corner – finding its way into seams and openings.  Irregular shapes found in conventional frames and  firewalls become ‘gas traps’ focusing blast energy.  These nooks and crannies are exactly what the designers of mine- resistant vehicles tried to avoid. Combining gas traps with  light weight  is a recipe  for  disaster. Vehicles like the Nyala APVs, which were designed to thwart the effects of  landmines,  have hulls care- fully shaped  to deflect blasts from below.  Usually, this means a ‘V’-shaped bottom with a minimum of angles or excrescences, allowing the blast to ‘flow’ unimpeded past the structure.  Parts of  the vehicle likely to be in the path of the blast are designed to be sacrificed – wheels and axles are easily blown off but such running gear parts can be just as readily re-attached. It is vehicles such as these that can properly be defined as ‘blast-resistant’. While tanks were shaped to deflect shells from the front and sides, the Nyala specializes in deflecting blast and fragments from below. This mine-resistant hull is not a new idea but it has taken considerable time for it to be accepted by Western armies. [4] [1] The APV crew was only jolted  but the IED blast injured an Afghan bystander. However, on 07 Oct 2006, the CF suffered its first  fatality in an RG-31 Nyala APV. [2] The APV’s ability to withstand a blast from below was not at issue. In question was how the Nyala would handle IED blasts from the side. USMC experience with RG-31s in Iraq shows that exposed gunners can be subjected to upper body burns and crush injuries from blast.  That alone seems to justify the expense, complexity, and weight of the CF APV’s roof-top Kongsberg M151  Remote Weapons Station. [3] Mowag did considerable blast testing on different LAV designs in Switzerland. In Canada, DREV tested AVGPs (both Cougar and ‘Brizzly’) and half-hull LAV III models. At Suffield, AVGPs were tested along with LAV IIIs (and the Piranha IV). [4] Canada was among the first to accept mine-resistant vehicles but only as route provers. Using such vehicles for patrol duty was new for the northern hemisphere. Next in this In Detail Review –  ‘Scatterlings’: Blast-Resistant Vehicle Origins