OUR AIRCRAFT: THE PBJ-1 MITCHELL
Marine Bombing Squadron Six-Thirteen operated North American PBJ-1s; the navalized equivalent of the Army's famous B-25 twin-engine Mitchell bomber.
Marine Bombing Squadron Six-Thirteen‘s operational strength while serving in the Pacific consisted of 15 PBJ-1H aircraft. Prior to deploying, VMB-613 utilized various models of the PBJ. A brief description of the squadron's use of each model is provided below. Further details on each model, including technical drawings and photographs can be found at: http://www.pbjmitchell.com
The first PBJs assigned to VMB-613 were PBJ-1Cs, the naval equivalent of the U.S. Army Air Force's (USAAF) B-25C. They were equipped with dual controls, and had their underside turret removed and a radome housing AN/APS-2 ("George") search radar installed in its place. PBJ-1Cs operated by VMB-613 were armed with five .50 caliber machine guns—one in the nose in a flexible mount, two fixed .50 caliber machine mounted on the starboard side of the nose firing through holes cut into the side of the Plexiglas glazing, and two in a power operated turret in the after mid-section.
In late January of 1944 the squadron received PBJ-1Ds. Most of these D-model PBJs were configured and armed the same as the older C-models. However, a number of the squadron's PBJ-1Ds were modified with the addition of a manually-operated gunner’s position in the tail similar to later model B-25s, and seven additional .50 caliber machine guns—one in the tail, one on each side in the waist position, and four "package guns" (two on each side) below the pilot's compartment. VMB-613's use of this type of aircraft was short lived, for they were withdrawn in March and April 1944 to receive radar modifications, and were subsequently sent into combat with replacement crews for the Marine Bomber Squadrons that preceded VMB-613’s deployment overseas.
Marine Bombing Squadron Six-Thirteen also received a J-model PBJ at the end of July 1944, however its use was virtually nil as it was immediately flown to the Consolidated-Vultee Modification Center at Elizabeth City, North Carolina for radar installation and naval modifications and was subsequently replaced with a PBJ-1H.
The last type of aircraft received, and subsequently used in combat operations by VMB-613, was the PBJ-1H. This aircraft boasted very heavy armament which included a 75mm T13E1 cannon and a total of 14 .50 caliber machine guns—four in the nose, four package guns (two on each side) below the pilot's compartment, one on each side in slightly staggered waist positions, two in a power operated Bendix Model "R" turret, and two in a power operated Bell type M-7 turret in the tail of the aircraft. In addition to the armament, these aircraft were heavily modified for Marine Corps use. Modifications included the addition of AN/APS-3 ("Dog") search radar in a radome on the starboard wingtip, AN/APN-4 Loran receiver, APK-2 IFF, AN/APN-1 radar altimeter, SCR-522A VHF radio, ARN-8 marker beacon, C-1 automatic pilot, ATC radio transmitter, ARB receiver, YC-2B receiver, BC-348 liaison receiver, and the AN/APG-13A ("Falcon") 75mm radar gun director. Further modifications to the aircraft took place once VMB-613 arrived overseas. Most notably, due to the absence of Japanese aircraft, the top turret was removed and an astrodome was installed in its place. This modification reduced the crew by one, the mechanic-gunner, saving weight and increasing the aircraft's range. Later modifications included the elimination of the four package guns, a modification which further increased the aircraft's range.
Although the PBJ-1H was only equipped with a single set of controls, all of VMB-613's aircraft carried two qualified naval aviators (pilot and co-pilot), with the copilot's primary duties being the operation of the radar gun sight and assisting the pilot. Additionally, the pilot and co-pilot would often switch seats in flight in order to reduce fatigue and maintain the co-pilot's effectiveness in flying the aircraft. The navigator sat in a station behind the pilot and copilot, and had the additional duty of loading the 75mm cannon. Two radio-gunners, whose primary duties were to operate and monitor the search radar and communications equipment, manned single flexible mounted machine guns in the waist positions. Completing the crew, a mechanic-turret gunner manned the top turret, while in the rear, an armorer-turret gunner operated the machine guns in a power-operated tail turret.
All of VMB-613's PBJ-1Hs were initially finished in the three-tone color scheme adopted by the U.S. Navy in March of 1944—sea blue, intermediate sea blue, and white. An unusual feature of this color scheme was that the sea blue on the upper surfaces was carried over onto the leading edges of the lower surfaces of the wing and horizontal stabilizer. The squadron number for each aircraft was stenciled in large white numbers within a dark-colored rectangular box below the aircraft's Bureau Number on the vertical stabilizer. The purpose of this dark-colored rectangular box was simply to obliterate the original two-digit aircraft numbers used stateside while the squadron was training.
While overseas the commanding officer permitted the application of rudimentary names to each aircraft. Painted in white, each aircraft's name appeared in a semi-circular fashion on the port side of the aircraft above the opening for the 75mm cannon blast tube. The names which have been documented include 8-Ball, Betty Lou, Bung-Ho!, Fireball, Flaming Fury, Green Weenie, Ladders Up, Long Gone, Love Bug, Marlene, Miss-Carriage, and Pregnant Annie. Eventually paint was removed from leading edges of wings, center section of the fuselage, empennage, engine cowling, and nose of each aircraft leaving the surface of these areas in a natural aluminum finish. Once this had been done, the names of the individual aircraft were not reapplied. This local modification to the standard paint scheme was simply due the inability to maintain paint on these surfaces due to the amount of coral sand that was constantly blown around on the flight line, and the maintenance and runway areas.
The configuration of our aircraft and our squadron's typical markings while overseas is illustrated below.
General Characteristics: The North American PBJ-1H medium bomber airplane was a mid-wing land-based monoplane powered by two Wright Cyclone engines. Characteristic features included a tricycle landing gear, and a double fin and rudder empennage. In addition to carrying up to fourteen .50 caliber machine guns and a 75mm cannon, the PBJ-1H was also equipped to carry bombs, depth charges, 5-inch rockets, or an aerial torpedo.
Basic Model: North American B-25H-5.
Wingspan: 67 feet 6 inches.
Wing Area: 610 square feet.
Length: 51 feet 4 inches.
Height: 16 feet 4 inches.
Weight (Empty): 19,600 pounds.
Weight (Maximum Loaded): 33,500 pounds.
Maximum Speed: 239 knots (275 mph) at 15,000 feet.
Cruising Speed: 200 knots (230 mph).
Stall Speed: 79 knots (90 mph).
Service Ceiling: 24,800 feet.
Range: 1,173 nautical miles (1,350 statute miles) with 3,000 pounds of bombs.
Crew: Seven (Pilot, Copilot, Navigator-Bombardier, 2 Radio-Gunners, Mechanic-Turret Gunner, and Armorer-Turret Gunner).
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