World War II: Consolidated B-24 Liberator

B-24 Liberator in flight
Consolidated B-24 Liberator. Photograph Courtesy of the US Air Force

B-24 Liberator - Specifications (B-24J):

General

  • Length: 67 ft. 8 in.
  • Wingspan: 110 ft.
  • Height: 18 ft.
  • Wing Area: 1,048 sq. ft.
  • Empty Weight: 36,500 lbs.
  • Loaded Weight: 55,000 lbs.
  • Crew: 7-10

Performance

  • Power Plant: 4 × Pratt & Whitney R-1830 turbo-supercharged radial engines, 1,200 hp each
  • Combat Radius: 2,100 miles
  • Max Speed: 290 mph
  • Ceiling: 28,000 ft.

Armament

  • Guns: 10 × .50 in. M2 Browning machine guns
  • Bombs: 2,700-8,000 lbs. depending on range

Origins:

In 1938, the United State Army Air Corps approached Consolidated Aircraft about producing the new Boeing B-17 bomber under license as part of the "Project A" program to expand American industrial capacity. Visiting the Boeing plant in Seattle, Consolidated president Reuben Fleet assessed the B-17 and decided that a more modern aircraft could be designed using existing technology. Subsequent discussions led to the issuing of USAAC Specification C-212. Intended from the outset to be fulfilled by Consolidated's new effort, the specification called for a bomber with a higher speed and ceiling, as well as a greater range than the B-17. Responding in January 1939, the company incorporated several innovations from other projects into the final design which it designated the Model 32.

Design & Development:

Assigning the project to chief designer Isaac M.

Laddon, Consolidated created a high-wing monoplane that featured a deep fuselage with large bomb-bays and retracting bomb-bay doors. Powered by four Pratt & Whitney R1830 twin Wasp engines turning three-bladed variable-pitch propellers, the new aircraft featured long wings to improve performance at high altitude and increase payload.

The high aspect ratio Davis wing employed in the design also allowed it to have a relatively high speed and extended range. This latter trait was gained due to wing's thickness which provided additional space for fuel tanks. In addition, the wings possessed other technological improvements such as laminated leading edges. Impressed with the design, the USAAC awarded Consolidated a contract to build a prototype on March 30, 1939.

Dubbed the XB-24, the prototype first flew on December 29, 1939. Pleased with the prototype's performance, the USAAC moved the B-24 into production the following year. A distinctive aircraft, the B-24 featured a twin tail and rudder assembly as well as flat, slab-sided fuselage. This latter characteristic earned it the name "Flying Boxcar" with many of its crews. The B-24 was also the first American heavy bomber to utilize tricycle landing gear. Like the B-17, the B-24 possessed a wide array of defensive guns mounted in top, nose, tail, and belly turrets. Capable of carrying 8,000 lbs. of bombs, the bomb-bay was divided in two by a narrow catwalk that was universally disliked by air crews but served as the fuselage's structural keel beam.

An Evolving Airframe:

An anticipated aircraft, both the Royal and French Air Forces placed orders through the Anglo-French Purchasing Board before the prototype had even flown.

The initial production batch of B-24As was completed in 1941, with many being sold directly to the Royal Air Force including those originally meant for France. Sent to Britain, where the bomber was dubbed "Liberator," the RAF soon found that they were unsuitable for combat over Europe as they had insufficient defensive armament and lacked self-sealing fuel tanks. Due to the aircraft's heavy payload and long range, the British converted these aircraft for use in maritime patrols and as long range transports. Learning from these issues, Consolidated improved the design and the first major American production model was the B-24C which also included improved Pratt & Whitney engines.

In 1940, Consolidated again revised the aircraft and produced the B-24D. The first major variant of the Liberator, the B-24D quickly amassed orders for 2,738 aircraft.

Overwhelming Consolidated's production capabilities, the company vastly expanded its San Diego, CA factory and built a new facility outside of Fort Worth, TX. At maximum production, the aircraft was built at five different plans across the United States and under license by North American (Grand Prairie, TX), Douglas (Tulsa, OK), and Ford (Willow Run, MI). The latter built a massive plant at Willow Run, MI that, at its peak (August 1944), was producing one aircraft per hour and ultimately built around half of all Liberators. Revised and improved several times throughout World War II, the final variant, the B-24M, ended production on May 31, 1945.

Other Uses:

In addition to its use as a bomber, the B-24 airframe was also the basis for the C-87 Liberator Express cargo plane and the PB4Y Privateer maritime patrol aircraft. Though based on the B-24, the PBY4 featured a single tail fin as opposed to the distinctive twin tail arrangement. This design was later tested on the B-24N variant and engineers found that it improved handling. Though an order for 5,000 B-24Ns was placed in 1945, it was cancelled a short time later when the war ended. Due to the B-24's range and payload capabilities, it was able to perform well in the maritime role, however the C-87 proved less successful as the aircraft had difficulty landing with heavy loads. As a result, it was phased out as the C-54 Skymaster became available. Though less effective in this role, the C-87 fulfilled a vital need early in the war for transports capable of flying long distances at high altitude and saw service in many theaters including flying the Hump from India to China.

All told, 18,188 B-24s of all types were built making it the most produced bomber of World War II.

Operational History:

The Liberator first saw combat action with the RAF in 1941, however due to their unsuitability they were reassigned to RAF Coastal Command and transport duty. Improved RAF Liberator IIs, featuring self-sealing fuel tanks and powered turrets, flew the type's first bombing missions in early 1942, launching from bases in the Middle East. Though Liberators continued to fly for the RAF throughout the war, they were not employed for strategic bombing over Europe. With the US entry into World War II, the B-24 began to see extensive combat service. The first US bombing mission was a failed attack on Wake Island on June 6, 1942. Six days later, a small raid from Egypt was launched against the Ploesti oil fields in Romania.

As US bomber squadrons deployed, the B-24 became the standard American heavy bomber in the Pacific Theater due to its longer range, while a mix of B-17 and B-24 units were sent to Europe. Operating over Europe, the B-24 became one of the principal aircraft employed in the Allies' Combined Bomber Offensive against Germany. Flying as part of the Eighth Air Force in England and the Ninth and Fifteenth Air Forces in the Mediterranean, B-24s repeated pounded targets across Axis-controlled Europe. On August 1, 1943, 177 B-24s launched a famous raid against Ploesti as part of Operation Tidal Wave. Departing from bases in Africa, the B-24s struck the oil fields from low altitude but lost 53 aircraft in the process.

While many B-24s were hitting targets in Europe, others were playing a key role in winning the Battle of the Atlantic. Flying initially from bases in Britain and Iceland, and later the Azores and the Caribbean, VLR (Very Long Range) Liberators played a decisive role in closing the "air gap" in the middle of the Atlantic and defeating the German U-boat threat. Utilizing radar and Leigh lights to locate the enemy, B-24s were credited in the sinking of 93 U-boats. The aircraft also saw extensive maritime service in the Pacific where B-24s and its derivative, the PB4Y-1, wreaked havoc on Japanese shipping. During the course of the conflict, modified B-24s also service as electronic warfare platforms as well as flew clandestine missions for the Office of Strategic Services. 

While a workhorse of the Allied bombing effort, the B-24 was not hugely popular with American air crews who preferred the more rugged B-17. Among the issues with the B-24 was its inability to sustain heavy damage and remain aloft. The wings in particular proved vulnerable to enemy fire and if hit in critical areas could give way completely. It was not uncommon to see a B-24 falling from the sky with its wings folded upwards like a butterfly. Also, the aircraft proved highly susceptible to fires as many of the fuel tanks were mounted in the upper parts of the fuselage. In addition, crews nicknamed the B-24 the "Flying Coffin" as it possessed only one exit which was located near the tail of the aircraft. This made it difficult to impossible for the flight crew to escape a crippled B-24.

It was due to these issues and the emergence of the Boeing B-29 Superfortress in 1944, that the B-24 Liberator was retired as a bomber at the end of hostilities. The PB4Y-2 Privateer, a fully navalized derivative of the B-24, remained in service with the US Navy until 1952 and with the US Coast Guard until 1958. The aircraft was also used in aerial firefighting through 2002 when a crash led to all remaining Privateers being grounded.

Selected Sources