The Cruiser Mk VI was a Self Propelled Anti Aircraft vehicle designed in 1942, manufactured by Nuffield, it was based on the fully tracked A13 III(Covenanter) chassis and was in use from 1943 to 1945. It was commonly called a Crusader III AA MkIII. General Details (SP Anti Aircraft) Specifications Operational Date(s) 1943 - 1945 Ordnance classification A15 Quantity Produced 5300 Weight 20 tonne Crew 5 M.G's small n/a M.G's large(>10mm) n/a Length 6.05 mtr Width 2.66 mtr Height 2.26 mtr Engine Details/Performance Max Road Speed 28 mph Max Cross Country Speed 15 mph Range Road 112 miles Range Cross Country 44 miles Fuel Type Petrol Fuel Capacity 120 gal Horse Power 340 hp Power/Weight 17 hp/tonne General Information The Cruiser Mk VI was a Self Propelled Anti Aircraft vehicle designed in 1942, manufactured by Nuffield, it was based on the fully tracked A13 III(Covenanter) chassis and was in use from 1943 to 1945. It was commonly called a Crusader III AA MkIII. The vehicle was powered by Nuffield 'Liberty' petrol powerplant producing 340 HP which could drive the vehicle on roads at up to 28 mph with a range of about 112 miles before refuelling. Its cross country performance was good providing a max speed of about 15 mph and a range of about 44 miles. Its main armament consisted of an Oerlikon 20mm L/70 weighing 0.130 kg and with a maximum range of 914 metres. The Crusader tank was a redesigned A13 Mk III as a heavy cruiser tank that could rapidly move and provide good A/T performance. The turret was a complex angular shape holding the twin Oerlikon 20mm guns in a high angle mount. The auxiliary machine gun turret was removed in this version. Armour Details Turret Front 49mm @ 7° (49mm) Side 24mm @ 45° (34mm) Rear 30mm @ 32° (35mm) Top 12mm @ 90° (12mm) Superstructure Front 30mm @ 38° (38mm) Side 14mm @ 0° (14mm) Rear 28mm @ 11° (29mm) Top 7mm @ 90° (7mm) Hull Front 20mm @ 60° (40mm) Side 14mm @ 0° (14mm) Rear 28mm @ 11° (29mm) Top 7mm @ 90° (7mm) Armour (x)mm @ (y)° (Effective mm @ 0°) Effective Armour - Maximum 49 mm - Minimum 7 mm Weapon Details Oerlikon 20mm L/70 (Anti Aircraft) x 2 History Manufactured in Switzerland the first British imports arrived in 1940, and subsequently manufactured under licence in Ruislip London later in 1940. Two versions were manufactured with different barrel lengths L/70 and L/85 which gave muzzle velocities of 820m/sec L70 and 1050m/sec L/85. The L/70 could deliver shells at 450rpm and the L/85 at 900-1000 rpm. Manufactured 1940 - Present Calibre 20mm Length L/70 Ammunition Details Name/Id Calibre Weight MVelocity Explosive Content 20x101RB (HE High Explosive) 20mm 0.13Kg 750M/Sec ≈0.02Kg explosive Maximum Range 914 Mtr Range(Mtr) 100 200 400 800 1200 1600 2000 2400 Flight Time(Secs) 0.14 0.29 0.61 1.38 2.28 3.28 4.36 5.49 lateral dispersion means the side to side variation of the shell from the aiming point 50%(CEP) of shells land within +/- (mtr) 0.12 0.12 0.12 0.21 0.00 0.00 0.00 0.00 80% of shells land within +/- (mtr) 0.15 0.15 0.15 0.27 95% of shells land within +/- (mtr) 0.24 0.24 0.24 0.41 range dispersion means the back to front variation of the shell from the aiming point 50%(CEP) of shells land within +/- (mtr) 0.15 0.15 0.15 0.27 80% of shells land within +/- (mtr) 0.19 0.19 0.19 0.35 95% of shells land within +/- (mtr) 0.29 0.29 0.29 0.53 Direct Fire Range(Mtr) 100 200 400 800 Flight Time(Secs) 0.14 0.29 0.64 1.47 Hit Probability(%) 74 74 72 62 Blast/Fragmentation Effects Burst radius Infantry in open 99% kill 1 mtr Burst radius Infantry in open 66% kill 2 mtr Burst radius Infantry in open 33% kill 7 mtr  Armour Penetration inc roof at 1 mtr 0 mm An explosion within 1 mtr of infantry in the open will cause 99% casualties - lethal. An explosion within 2 mtr of infantry in the open will cause > 66% casualties and could damage some AFV's. An explosion within 7 mtr of infantry in the open will cause 33% casualties. The blast effect of this shell exploding within 1 mtr of an armoured vehicle will not cause any significant armour damage. About Penetration Figures All penetration figures in this database are calculated to a common standard based on German WWII testing criteria (complete penetration with functioning fuze). This allows direct comparison between all nations' guns. Original national test figures would be higher for some nations due to different criteria: German: 1.00? (baseline - strictest) British: 1.02? (slightly looser) American: 1.05? (50% mass through plate) Soviet: 1.10? (75% mass through plate) For example, a Soviet gun showing 159mm here would be published as ~175mm in Soviet documents, and a German gun showing 120mm would be published as 120mm in German documents. The 159mm figure is directly comparable to the German 120mm - the Soviet gun really was more powerful. National Testing Standards German: 1.00? - Complete penetration, fuze functions (strictest) British: 1.02? - Complete penetration American: 1.05? - 50% of shell mass through plate Soviet: 1.10? - 75% of shell mass through plate All database figures are normalized to German standard for direct comparison. Multiply by the factor above to see original national test figures.

Hit probability is based on a static 2 x 2.4 metre panel at 0 degrees(vertical) at the range specified.

The data that has been used to create these records has come from Wikipedia, The Lone Sentry, The Bundes Archive and numerous books and websites that have provided the detailed information that has not been available anywhere else. The information we use to calculate the penetration tables, flight times and the hit probability comes from the Gun Calibre, the Shell Mass(Kg) and the muzzle velocity, plus range reductions to allow for gravity and wind resistance. This calculation originally came from a pre-war Krupp calculation which has been modified, and seems to fit the actual test results.

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