The Consolidated Vultee B-24 Liberator

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As the olive-green jeep drove round the quad-engined Consolidated Vultee B-24 Liberator, the morning, sun, unobstructed by the flawlessly blue sky, glinted off the sides of aircraft 252534 “Witchcraft” and the Boeing B-17 Flying Fortress 231909 “Nine-o-Nine” on that early September 2005 day at Farmingdale’s Republic Airport on Long Island

About to sample a flight aboard this B-24 aerial bomber, I somehow felt as if I had entered a World War II time warp.

The Consolidated Vultee B-24 Liberator had had its origins in the 1938 US Army Air Corps requirement for a long-range, high-capacity bomber able to cruise at 300 mph and 30,000 feet, with a 3,000-mile range.  Although it had initially been envisioned that Consolidated Aircraft would produce existing B-17s, it had been able to design an entirely new long-range, four-engined, heavy bomber in virtually the same time that it would have taken for it to convert its current San Diego production line, building an initial mock-up in January of 1939, three months before the contract between Consolidated and the Army Air Corps had been signed on March 30.  The prototype, designated XB-24, first flew by the end of the year, on December 29, with full-scale production commencing the following autumn for the United States, British, and French governments.

The design, as reflected by the dark green-livery aircraft with a red-and-white diagonal stripe before me, had featured an aluminum alloy monocoque structure built up of five main bulkheads and covered with stressed Alclad skin of 67.2 feet length with a glazed nose turret, a raised cockpit windscreen, a top turret, ventral bomb bay doors which retracted to form the fuselage underside, two rectangular waist-gunner apertures, and the glazed tail turret.  Sporting two high-mounted, cantilever wings, whose planform had been based on that of the Model 31 flying boat, it utilized a high aspect ratio Davis airfoil of all-metal construction, consisting of the center and two outer sections with detachable wing tips, and continual taper from their fuselage mating points to their tips.  The increased spacing between the front and rear spars permitted additional fuel tankage and hence range.  The outboard, metal-framed ailerons were fabric-covered, while hydraulically-actuated, area-increasing, trailing edge Fowler flaps, warped to conform to the wing underside planform taper, stretched between the ailerons and the fuselage root and replaced the less effective split flaps of the comparable B-17.  At 110 feet, the wings offered a total area of 1,048 square feet.

Four PBY engine packages housed 1,200-horsepower Pratt and Whitney two-speed, super-charged R-1830-33 pistons with three-bladed, Hydromatic, full-feathering Hamilton Standard propellers.

The all-metal horizontal stabilizers, sporting twin vertical tails with fabric-covered, metal leading edge rudders, equally featured fabric-covered elevators and offered a radical departure from the conventional, single-tail of the Flying Fortress.

The tricycle undercarriage, replacing the less stable bicycle arrangement of the B-17, featured a rearward-retracting single nose wheel storable in the fuselage-integral, door-enclosed wheel well and the two single, lateral- and outward-retracting main wheels which were housed in uncovered wing-underside fairings between the in- and outboard engines.  All had been mounted to oleo struts and had been actuated by hydraulic jacks.

The aircraft, of 60,000 pounds gross weight, could attain a maximum speed of 297 mph at 25,000 feet and fly 1,540-mile sorties with normal fuel and its maximum bomb load at a 237-mph average speed.

The first B-24 version, powered by the R-1830-33 engines and entailing a production run of only 26, had been built in San Diego and flown to the United Kingdom for operation by the British government, but initial experience had indicated that they had been unsuitable for their intended European combat missions and they had therefore been forcibly converted to transports, without armor, for use on the Trans-Atlantic Return Ferry Service.

The Liberator’s development, although initially protracted, ultimately led to the B-24A, which had featured four 20 m/m cannons in below-forward fuselage fairings, two .303-inch waist guns, one .303-inch tunnel gun, and two .303-inch tail guns, and had entered service with the Royal Air Force Coastal Command.

The LB-30, built entirely to British specifications, had been powered by four two-speed supercharged R-1830-S3C4G engines with Curtiss Electric full-feathering air screws.

The XB-24B had sported turbo-supercharged piston engines with self-sealing tanks and armor.

The B-24C, the succeeding version powered by R-1830-41 engines with exhaust-driven turbo-superchargers, had featured power-driven dorsal and tail turrets, each with .50-caliber guns.

The subsequent derivative, the B-24D, offered ultimate armament capability, with ten .50-caliber guns, of which two additional ones had been installed in the nose and one additional one had been installed in the tunnel.  Powered by R-1830-43 engines, the more capable version contained auxiliary self-sealing fuel tank cells in the outer wings, thus increasing overall fuel capacity and aircraft range, with further tankage installation capability in the bomb bays.  The B-24D could carry two 4,000-pound bombs, each attached to a rack under either wing.

Several other derivatives, differing in armament provision, anit-icing capability, and production method, followed.

Although the Liberator had fought in many theaters during the outbreak of WWII, among them England, the Middle East, and the Aleutians, by 1943 it had entirely replaced the Flying Fortress in the Pacific.

Seeking to rectify many of the design deficiencies associated with its dual-tail configuration, Consolidated Vultee had produced an experimental, single-fin version designated the XB-24K, whose tail components had been comprised of the stub attachment assembly, the dorsal fin, the horizontal stabilizers and their elevator surfaces, the vertical tail itself, its trim-tabbed rudder, and the tail turret fairing.  The larger, increased-area tail improved the aircraft’s lateral stability and its larger rudder had proven more effective during dual-engine-out conditions on a single side.  Re-designated the B-24N, the R-1830-75-powered derivative featured a streamlined Emerson Model 128 spherical nose turret, which vastly increased bombardier and navigator visibility, improving target aim and firing accuracy.  The turret’s reduced drag profile, coupled with that of the singular, although much larger vertical fin, increased the aircraft’s range capability with a 5,000-pound payload at maximum power settings by 300 miles.  A revised canopy, which reduced the number of rib-interspersed panes, also improved cockpit visibility.  Although the design had offered entirely greater capability, its late appearance at the end of the war had resulted in a short production run of only a few examples.

The B-24M had been the 6,725th and last of the basic configuration to have been produced by Consolidated Vultee in San Diego.

Nevertheless, the basic B-24 Liberator had more than proven its worth: by the time the last airframe had rolled off the production line on May 31, 1945, 18,479 aircraft of all versions had been built by Consolidated Vultee itself, Douglas, Ford, and North American, and had served the Army Air Corps, the Navy, and 15 Allied nations in every theater of war, having operated more missions and having dropped more bombs than any other single World War II design.

The aircraft intended for today’s flight, a B-24J, had been produced in August of 1944 by Consolidated Aircraft in Fort Worth, Texas, and had been delivered to the RAF two months later, in October, which had operated it in the Pacific in a multitude of roles, including bombing, anti-shipping, and resupplying resistance force operations, until the war had ended.

After listening to the pre-departure safety briefing on the ramp that September morning, the day’s seven passengers accessed the mighty, quad-engined bomber through its extended, under-fuselage bomb bay doors, balancing on one foot along the catwalk and climbing up toward the aft cabin, where three claimed the aft-facing, seatbelt-equipped bench ledge seats and the other three the lower floor positions.  The seventh had followed the catwalk forward to the radio operator’s station.

Momentarily belching black smoke as its four Pratt and Whitney R-1830 piston engines ignited into deep, throaty Hamilton Standard propeller rotations at 0900, the dark green-liveried Liberator, retracting its bomb bay doors and ventral hatch and testing its flight surfaces, released its brakes and advanced its throttles, inching over the American Airpower Museum ramp on to the taxiway upon clearance from Republic Ground on 121.6.  Paralleling the active runway, 32, and increasing ground speed, the mass of aluminum was buttressed by slipstream-produced winds entering its cabin through the opened waist gunner stations, the rudders continually deflected during its slow roll, as evidenced by the incessant pulley travels in the aft fuselage.  Taxiing, according to today’s copilot, had been difficult, despite the design’s B-17-improved tricycle undercarriage configuration, because of the gear’s relatively close-intervaled geometry, and the full-castering nose wheel caused a swinging tendency, creating the need for brake dependency and differential power applications. 

After a pause for a full run-up and flight surface deflections, the mammoth bomber, now trailed by its Flying Fortress counterpart, received take off clearance from Republic Tower on 125.2 and made the 180-degree right turn on to the threshold of the 6,827-foot runway, poised for initial transition from grounded, dead-weight, metallic tractor cushioned by rubber tires to airborne, majestic, wing-flexed bird cushioned by air.  Farmingdale, I thought, your World War II purposesare not over yet!  Advancing its four throttles and engulfed in a deafening cocoon of Twin Wasp noise emissions, the engines, gulping fuel like a thirst-deprived man in the desert, converted energy to propeller-scooping motion, sending fierce slipstream through the waist gunner stations and over the horizontal and vertical tail surfaces.  The man scrouched on the cabin’s left side proclaimed, “We’re rolling!” an expression I had heard countless times while watching acceleration rolls on the ground, but which somehow took on never-tiring, excitement-provoking meaning when coupled with the actual maneuver in the aircraft.

Maintaining 2,700-rpm and 41-inch manifold pressure settings on its engines, the behemoth moved through 90 mph, pulling back on its elevator-deflecting control yoke and, winning a metal machine-to-force of earth battle, surrendered itself to the sky in triumph with its straight, outstretched, suddenly graceful-appearing wings.  Retracting its drag-inducing, still-spinning undercarriage over Route 110, Witchcraft adhered to the airport’s nose abatement procedure, gently banking right on to a 010, almost northerly heading.  Throttling back to a 2,300-rpm and 31-inch manifold pressure setting, the B-24J, assuredly the envy of Republic’s multitude of daily departures and a giant in ratio to its almost toy-appearing general aviation singles, surmounted green-carpeted Long Island.  Through the starboard waist gunner’s window the monolithic high rises of Manhattan, although miniaturized from the current distance, could be seen.

Having rapidly accelerated to a 175-mph air speed, the bomber, further throttled into a 2,000-rpm and 30-inch manifold pressure setting, attained its cruise altitude of 1,500 feet over the velvet azure of Long Island Sound and its North Shore.  The four red-and-white candy-striped Northport Stacks passed below the right cockpit windows in miniature.  The aircraft banked to an easterly, 095-degree heading, maintaining the 2,000-rpm setting of its engines and the VFR 1200 frequency of its transponder.

The cruise mode induced a closer internal inspection.  The glazed, Plexiglas nose turret, projecting itself well ahead of the cockpit windows and location of the bombardier, had provided forward visibility and power-driven armament.  A below-floor crawl shaft led to the radio operator’s station, which featured a single, aft-facing, seat-belted floor position and a side-facing console with two small rectangular windows, directly below the roof turret and one step below the two-person canopied cockpit.  A foot-wide catwalk accessed the two bomb bays, which offered double the capacity of that of the comparable B-17.  Beyond had been the aft cabin with its ventral, extendible ball turret; two side-mounted tail turret ammunition storage racks; the two side-facing waist gunners’ stations; and, through the bulkhead, the fuselage-tapering tail turret which, located behind the empennage, provided a 180-degree, eye-level view of the constant deflections of the slipstream-bombarded horizontal stabilizers.  A crew of ten had standardly operated the B-24.

The wing tips, from the cockpit vantage point, had not been visible.  Skirting Long Island’s North Shore, the mammoth, metallic bomber moved toward Port Jefferson, its large passenger and vehicular ferry approaching the harbor under the right wing after another Long Island Sound crossing from Bridgeport, Connecticut.  Burning 637 gph of fuel at its take off power settings and a current 200 gph during cruise, it banked left out over the mirror blue surface of the water, its four engines fed by the wing-integral, foam-insulated kevlar fuel tanks whose total capacity had been reduced from the 2,300 gallons of the production version to the present 1,400 gallons.  Altitude could be maintained on any two powerplants.

The transition to the B-24, according to the copilot, had been difficult, particularly from the B-17, because of its flying characteristics.  Pitch-sensitive, the aircraft had a heavy elevator feel, although the ailerons provided a standard banking sensation.  Because of the fuselage area, it performed exemplary during side-slips, and its dual vertical fins and rudders were particularly effective.

Banking inland, Witchcraft recrossed the North Shore.  A reflection of the massive bomber tracked the ground, like a shadow.  Indeed, the aircraft itself had been a shadow of its once numerous brethren.  Sadly, it had been the only remaining operational one.

                Maintaining a southerly heading, the Liberator radioed Republic tower its “inbound for landing” intention, passing to the right of the airport and extending its area-increasing Fowler flaps.  Arcing into a  right bank, to a 320-degree heading, it reintroduced its massive, oleo strut-attached tires into the slipstream and trimmed itself into a 120-mph approach speed.  Sinking toward the perimeter fence and passing over the runway’s threshold, it rotated into a still-airborne, power-reduced flare, its main wheels snatching concrete with a screech as they spooled up to the aircraft’s ground speed.

                Taxiing on to the American Airpower Museum’s ramp and swinging round to the left, it absorbed the vibration through its wing spar as the fuel-starved propellers decelerated, the B-17 taxiing into position from its South Shore sortie behind it.  Appropriately, as in World War II, the B-24 Liberator had started second, but had finished first.

                Once again climbing through the bomb bay doors to the ramp, I paused outside, marveling at the now-silent, motionless, though once-mighty bomber.  From the engineers who had designed it to the pilots who had flown it, the Consolidated Vultee B-24 Liberator had translated the technology of its design in to the triumph of its enemies.  I was proud to have experienced her.

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