CASR
Canadian American
Strategic Review
- Canadian Defence Policy, Foreign
Policy, & Canada-US Relations - |
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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?! CFs 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 vehicleborne 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 APVs 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 APVs 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
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