Italian
90 mm/50 (3.5") Model 1939
Updated 07 October 2006
These guns had good ballistic properties for their caliber, but the mountings were too advanced for their time and were plagued with many technical faults.   Used on quadaxial mountings of which the four axes were training, elevation, roll correction and pitch correction and required 11 gyros to operate in a very complex arrangement.  RPC was fitted but removed from the Duilo class in 1942, apparently because of water damage.  The Littorio class had their mountings much higher and retained RPC.

Consisted of autofretted monobloc barrel with a screwed-on breech ring holding the horizontal sliding breech block and seatings for the run-out and recoil cylinders.
WNIT_35-50_m1939_pic.jpg

90 mm/50 (3.5") from Caio Duilio now at the Milan Museum of Science and Technique
Picture copyrighted by Eugenio Vajna
WNIT_35-50_m1939_side_pic.jpg

Another view of above 90 mm/50 mounting
Picture copyrighted by Eugenio Vajna
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Gun Characteristics
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Designation 90 mm/50 (3.5") Model 1939
Ship Class Used On Doria and Littorio classes
Prototypes tried on San Giorgio
Manufacturer Ansaldo and OTO
Date of Design 1938
Date In Service 1940
Gun Weight 1.8 tons (1,960 kg)
Gun Length oa N/A
Bore Length 177.2 in (4.500 m)
Rifling Length N/A
Grooves N/A
Lands N/A
Twist N/A
Chamber Volume N/A
Rate Of Fire 12 rounds per minute
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Ammunition
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Type Fixed
Weight of Complete Round 40 lbs. (18 kg)
Projectile Types and Weights AA - 22 lbs. (10 kg)
Bursting Charge N/A
Projectile Length N/A
Propellant Charge 7.5 lbs. (3.4 kg)
Muzzle Velocity 2,822 fps (860 mps)
Working Pressure 19.37 tons/in2 (3,050 kg/cm2)
Approximate Barrel Life N/A
Ammunition stowage per gun N/A
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Range
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Elevation With 22 lbs. (10 kg) AA shell
Range @ 45 degrees 14,220 yards (13,000 m)
AA Ceiling about 35,400 feet (10,800 m)
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Mount / Turret Data
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Designation Single Mounts
   Doria (10) and Littorio (12)
Weight  18.77 tons (19.07 mt)
Elevation -3 / +75 degrees
Elevation Rate Manual operation, only
Train about +120 / -120 degrees
Train Rate Manual operation, only
Gun recoil 19 in (48.4 cm)
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Data from
"Naval Weapons of World War Two" by John Campbell
"Italian Warships of World War II" by Aldo Fraccaroli