The Consolidated B-24 Liberator was the Second World War’s most numerous Allied heavy bomber and – at over 18,000 made – the most produced American military aircraft.
It was operated by several Allied air forces (including the USAAF and the RAF) and navies, attaining a distinguished war record on operations in the Western European, Pacific, Mediterranean and China-Burma-India theatres.
Graeme Douglas, the author of our Consolidated B-24 Liberator manual, has been granted privileged access to several airworthy examples of the B-24 in the USA to give an unrivalled insight into the construction, operation and maintenance of this classic heavy bomber.
Below is Graeme’s in-depth description of the Liberator’s complex anatomy…
Anatomy of the B-24 Liberator
The Liberator design incorporated advances in aerodynamics and technology that were some five years more advanced than the Flying Fortress.
The most radical feature was perhaps the efficient, high aspect ratio Davis wing, which promised to bestow the Liberator with a low drag, high lift performance.
When this wing was married to the box-like Liberator fuselage and successive versions were required to carry ever increasing weights of military equipment, the performance promise of the early design became a distant memory.
But the clever design of the B-24s deep fuselage and twin bomb bays meant extra fuel could be carried in one bay and a useful load of bombs in the other, giving the aircraft exceptional range for its time.
FUSELAGE
The many different versions of the B-24 varied a great deal in the detail of their internal equipment. The description that follows is typical for a late production B-24J series, any significant variations with other versions are highlighted in the text.
The deep oval fuselage is of all-metal, stressed skin and is defined as a semi-monocoque design. Running longitudinally are rolled aluminium Z-section stringers spaced approximately 6in apart, but with reduced spacing where greater strength is required in areas such as the bomb bays.
Heavy section longerons carry loads through the bomb bays and other fuselage openings. Circumferential frames or stations are of aluminium lipped-channel and are notched to pass over the stringers and the spacing between stations is approximately 1ft 6in.
Numbering is from 0 which is a datum point in the extreme nose to the datum point 10.0 at the tail. Compartments are separated by stations with whole numbers with intermediate stations numbered 0.1, 0.2 etc.
There are five structural bulkheads, forward of the flight deck, aft of the flight deck, between the two bomb bays, aft of the rear bomb bay and at the end of the rear compartment just forward of the rear turret; these serve to separate different fuselage compartments as well as to add strength to the structure.
Alclad aluminium skin is attached to the stringers and stations by rivets to provide the stressed skin element of the structure. The design ensures that stresses are evenly dispersed throughout the airframe rather than being concentrated at a few points.
NOSE COMPARTMENT
This section, between the nose and station 1.0 contains the working area for the bombardier and navigator. The bombardier also manned the nose turret, usually either a Consolidated or Emerson type.
The Consolidated turret is a hydraulically powered unit, which is plumbed into the aircraft’s main hydraulic system, while the Emerson type A-15 is an electrically operated turret taking its power from the main 24volt system. It is entered via two doors; the gunner is seated with his feet resting in the turret bowl.
Below the turret is the Norden bomb sight looking through the optical glass panel. To the bombardier’s left is the bomb release panel, controlling the release sequence of the bombs and below it the Intervalometer controls the timing of the bomb release.
Just behind this sit the actuating levers for opening the bomb doors and for emergency salvo of the bombs. To his right, is the drift meter used to measure the effect of drift on the aircraft over the ground.
In B-24 D and E aircraft the front of the compartment consisted of a multi-panelled Plexiglass nose containing two or sometimes three machine guns.
Immediately behind the bombardier is the navigator’s table and swivel seat, the navigator sitting facing backwards at his table, on the bulkhead in front of him are his flux gate compass indicators and other navigational instruments.
At the rear of the compartment on the right hand side is the entrance to the crawl way running underneath the flight deck. This leads past the nose wheel and gives the crew access to the bomb bay and the rest of the aircraft.
FLIGHT DECK
The flight deck is positioned above the nose wheel, and behind the nose compartment between stations 1.0 and 4.1. At the front the pilots sit in their compartment with seats and controls for the pilot on the left and co-pilot on the right.
Immediately behind them is the Martin upper turret normally manned by the flight engineer. To the right of the compartment, behind the co-pilot, the radio operator has a work table and seat. The pilots each have linked control wheels which have a push and pull action into and out of the instrument panel to control the elevators.
Ailerons are operated by rotating the wheel in the normal sense. On the floor in front of each pilot are two pairs of linked rudder pedals each with toe brakes incorporated.
In front of the pilot’s panel are the main flight instruments, namely the directional gyro, gyro horizon, rate of climb indicator, airspeed indicator, turn and bank and altimeter. There are also a pilot directional indicator, suction gauge, hydraulic pressure gauge, and brake pressure gauges.
On the sidewall to the pilot’s left are controls for his oxygen and interphone connections. In front of the co-pilot are gauges related to engine management for fuel pressure, cylinder head temperature, oil pressure, oil temperature and carburettor air temperature.
Additionally he has gauges and switches for the anti-icer and de-icer systems. To the left of his control wheel is an electrical switch panel containing switches to operate the fuel booster pumps, engine starters, oil dilution and fuel priming system.
On his right sidewall, the co-pilot has further switches for the heater and defroster circuits, main batteries and for the magnetos.
Across the centre of the instrument panel, between the two pilots the instruments relating to the power developed by the engines are grouped, the manifold pressure gauges and tachometers.
All engine instruments are of the dual dial design, requiring one instrument per pair of engines. Just below these, almost in the centre of the panel the square control box for the automatic pilot is situated.
Positioned between the pilots the central control stand or pedestal contains engine and flight controls and more electrical switches. At the top, forward part of the pedestal is the turbo boost selector knob.
Earlier B-24s with the mechanical boost control had four levers in place of this control for adjusting the turbos on each engine individually. To the right of this are the four throttle levers and next to them four similar levers for the mixture control.
Further forward, switches controlling propeller pitch, intercooler shutters, cowl flaps and exterior lighting. The aileron trim control knob is in the centre of the top of the pedestal, within reach of both pilots, as is the rudder trim wheel, on the front face of the stand.
Down on the left side is the elevator control wheel, only reachable by the pilot. At the base of the pedestal on the pilot’s side is the landing gear control lever and on the co-pilot’s side the lever for raising and lowering the wing flaps.
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