By Frederick A. Johnsen
The B-24 was no stranger to the barbed epithet. More than any other bomber of WW II, it was the target of criticism. Even its own pilots couldn’t agree on its qualities, exemplalry or dubious. Yet practically any bomber pilot would agree that the Boeing B-17 was a timeless classic. But what about the B-24? Even today, the aircraft remains an enigma. More of them were built for States and its Allies than any other American aircraft, bomber or fighter. The Liberator served in more roles than any other aircraft on Air Force inventory. Even its detractors admit it was versatile. Nevertheless, it disappeared, almost overnight, by the end of 1945.
Faster, capable of carrying heavier loads for longer distances than the legendary Flying Fortress, the B-24 Liberator is still referred to as the B-17’s bastard half brother. Among the slurs cast at the hardworking, but unglamorous B-24 was the label “crate” … “the crate, the B-17 came in.” It was the unkindest cut of all. The Liberator could live down the others: Thundermug, Big Ass Bird, Agony Wagon, Twin Tailed Timebomb, but “a crate for the B-17,” that was way off base.
Sitting on the taxi way’ like a boxcar attempting to fly, its brakes hissing like a Greyhound bus, the B·24 looked dumpy. When heavily loaded, she had to be handled gingerly on take off. Airspeed was highly critical in the Liberator, particularly at low altitudes where any increase in drag guaranteed disaster. In formation, the pilot was constantly on the throttles. The B-24 did not fly well at high altitude and its best performance was invariably turned in at speed, otherwise the aircraft just hung in the sky, its engines struggling to keep the high-lift Davis Wing in the air.
Unlike the B-17, the B-24 was designed to carry cargo, any cargo, but preferably bombs. It was not designed as a flying machine, but rather a flying receptacle. Perpendicular to the long, nearly straignt wing, a cavernous oblong box was attached, with two huge rudders to give it directional control. This was the B-24’s fuselage. Lose power on the wing’s engines and it became difficult to direct the 32 ton gross-loaded air frei er. One engine out was trouble, but trl and auto-pilot would hold the big bomber steady. Two out on one side … prepare for a wake. Both pilots with their feet jammed down on the rudder pedals, holding against the turning impulse, going downhill all the time, was often not enough. To hold a 8-24 with two out, one had to have the strength of a Frank· enstein monster, and then some.
Nevertheless, the aircraft continued to serve and perform. As a patrol craft, long range transport and a bomber, it was probably the Air Force’s most versatile bird. Toward the end of WW II, when the later Liberators came out with ball bearing controls, the wheel and rudders turned feather light. Experience was also a great teacher and a good 8-24 pilot was the best. Maligned, short· changed and sold short, the “24” was still a tough old bird. She took punish· ment as well or better than her glamorous Boeing stablemate. Yet time ran out on the 8-24.
They make movies about the B-17. For the 8-24 there are only epitaphs, like that of the Lady Be Good, a luckless Liberator which went down in the Libyan Desert, with her crew, yet remained virtually intact, their tomb for over 16 years. Somewhere in that dusty saga lies the message and the truth about the “crate the 8-17 came in!” Over 18,000 Consolidated Liberators rolled off five production lines to become the most extensively produced aircraft in the history of the American aviation industry. The airplane bearing this unique claim readily metamorphosed throughout the Second World War, a fact which made its continued production feasible from 1939 to 1945·. In other words, a lot of jobs were found for the B-24, but its active life was a short one, and its employment was swiftly terminated.
Nevertheless, such a production record rests on a firm foundation. Conceived later than the Boeing B-17, with which it is usually associated, the B-24 employed many design improvements over the Flying Fortress. In fac!, after the advent of the tricycle-gear Liberator, Boeing engineers studied the feasibility of redesigning the B-17 to incorporate the tricycle gear arrangement instead of its wellknown main gear and tail wheel configuration. Consolidated first began seriously studying a multi-engine bomber design in january of 1939. By March 30th of that same year, the U.S. Army Air Corps was ready to order a prototype B-24 based on the studies of the previous months. From the outset, a major goal of Consolidated was to produce a bomber with range far superior to other contemporaries. To accomplish this, the high-lift Davis airfoil was employed with a high aspect ratio wing. One of the Liberator’s many questionable features, the Davis wing gave the B-24 sufficient range to make it the only aircraft in 1941 capable of serving as a non-stop, Canada-to-British Isles transport. It was this range factor which later made the Liberator a favorite for longrange Padfic missions.
The Davis wing’s efficiency was dependent upon a fair amount of speed, however, and slow-speed flight characteristics, especially when performed without benefit of flaps, could be marginal. When the B-24 did use its flaps, they ran out behind the wing, increasing its effective area. A single hydraulic jack supplied power to actuate flaps for both wings, the maximum flap setting of 40 degrees increasing lift by 55%, and drag by a whopping 70%.
The shoulder-mounted wing, plus the considerable width and depth of its fuselage gave the Liberator st.orage area to match its lifting capabilities. Thus was it possible for a 38,000 pound B-24 to hoist itself and 34,000 pounds of payload, fuel, crew, and ammunition into the air. This gross weight of 72,000 pounds is excep~ ional, operational gross weights usually ranging between 56,000 and 66,000 pounds, but the B-24 had been designed around its wing, with all the benefits and drawbacks the Davis airfoil entailed.
Consolidated bustled for nine months to incorporate B-24 concepts into being, and on December 29, 1939, the XB-24 first left Lindbergh Field to test its wings, eventually reaching a speed of 279 m.p.h. in later trials, while promising a range of 3,000 miles. War in Europe prompted France to order 120 untried B-24s at this time, while the British contracted for 164 of the bombers. The Army Air Corps ordered 7 YB-24s and 36 B-24As, the YB- 24’s notable distinction from the XB-24 being the addition of de-icer boots. With the demise of France in 1940, the unfilled French B-24 orders were added to the British batch. The English received the first production B-24s, which they christened “Liberators.” These first production airplanes bore the designation LB-30A, and had nodi rect American counterpart. For purposes of comparison, the LB-30A was basically the same airplane as the YB-24. They were followed in 1941 by RAF Liberator Is, which were virtually the same machines as the LB-30As, with the addition of hand-held armament and other operational features. The Liberator first entered bomber service in the form of RAF Coastal Command Liberator Is.
The British followed up on the Liberator I with a slightly stretched version known as the Liberator II. A little over two-and-a-half feet was added to the nose of the Liberator at this time, giving the plane the characteristic snout of all greenhouse B-24s to follow. Liberator II, which was a purely British aircraft, was the first of the line to carry power turrets, one Boulton Paul dorsal turret being placed midway along the fuselage, while another protected the tail.
The RAF employed B-24Ds as Liberator III or IIIA, depending on whether Boulton Paul or American armaments were used. Meanwhile, Army Air Corps Liberators were developing along similar lines. Only a handful of B-24As were delivered. These were similar to the Liberator I. Armament on the B-24A included six .50-caliber machine guns as opposed to the smaller-bore guns standard to the RAF. Two .30 caliber machine guns were mounted in the tail of B24s, and early use of Air Corps’ B-24As included the trail blazing of ferry routes criss-crossing the Atlantic and Pacific Oceans.
Most of the aircraft ordered under the B-24A contract were completed as later, improved models. The XB-24B, modified from the prototype XB-24, instituted the use of turbo-supercharged R-1830-41 engines as opposed to the R-1830-33s of 1200 hp. in the earlier models. Horsepower was the same, but performance at altitude was increased to 292 m.p.h. The cowlings and nacelles were redesigned to accommodate the turbo-supercharger units on the underside of each nacelle, relocating the oil coolers. It was this modification which gave the Liberator cowl its typical wide oval shape, the coolers now being housed on either side of each engine.
After the XB-24B came, quite logically, the B-24C. This variant had the elongated nose of the Liberator II and the oval cowlings of the XB-24B. The C-model was the first B-24 to employ the Martin dorsal turret, immediately behind the cockpit.
One of the most famous models of the entire Liberator line, the B-24D, resulted from the B-24C. An improvement on the C-model which included the substitution of R-1830-43 powerplants for the -41s brought into being the first U.S . combat model B-24 and a top speed of 303 m.p.h. at 25 ,000 ft., with a cruise of 200 m.p.h.
As the first Liberator version to be deployed in large numbers as an Air Corps bomber, much still remained to be learned about putting defensive armament to best advantage. The first B-24Ds featured three turrets – the Martin Model 250 dorsal turret, a Consolidated tail turret, and a Bendix belly, or “waist” turret, just aft of the bomb bay. Eventually all of the Bendix turrets were removed, and many B-24s were built without this feature at all. B-24Ds, without a ventral turret, often employed a “tunnel gun” firing downward through the aircraft’s rear entry hatch, located in the bottom of the fuselage. Late B-24Ds were also the first to incorporate a retractable Sperry ball turret to protect the plane ‘s underside.
Frontal protection initially consisted of only one hand-held .50 caliber gun, firing through the nose. B-24Ds from serial number 41-24220 on had two cheek nose guns added. One fired through a swivel in the greenhouse’s righthand side, while the other was mounted in a special window on the left side of the nose. All Air Corps B-24 armament was .50 caliber by this time, with the exception of a few .30s used in some hand-held installations.
Admittedly a more demanding airplane than its stablemate, the Flying Fortress, the B-24D picked up a bad reputation early in its career owing to a mysterious series of crashes due to failure of the tail structure. Extensive testing showed that the main gear set up a vibration upon contacting the runway on landing, and that this vibration matched the natural frequency of the structural members in the tail of the plane. This vibration cost several Liberators before steps were taken to strengthen the tail and change the frequency of its vibration.
There were other problems associated with the twin tails of the B-24, such as flutter induced by control cables being installed too loosely. Certain cowl flap settings on the inboard engines could also set up a buffeting in the tail surfaces by disturbing the air flow in front of the empennage. Controls were generally somewhat heavy on the B-24D, and reminiscing Liberator pilots are quick to recall the great amount of muscle required to horse the earlier B-24s around.
Thus it was that the Liberator grew from an unprotected silver prototype in 1939 to a formidable, if maybe clumsy, strategic bomber by 1942.
The B-24D was followed by a nearly identical plane with modified propellers, known as the B-24E. The first complete Liberators constructed by Ford under contract were E-models. Some Es featured R- 1830-65 engines, while others retained the -43s.
The only B-24F was, in actuality, a B- 24D, s/n 41-11678, converted to test experimental de-icing equipment. This XB- 24F bore the legend, “678 – The flying icing wind tunnel.”
The last of the greenhouse B-24s was the B-24G produced by North American at Dallas, Texas. These were basically D-model planes. Later Gs were the first production Liberators to incorporate a nose turret. But that’s another story.
Numerous model changes and role changes lay ahead for the Lib. These adaptations would capitalize on the B- 24’s inherent speed and range assets, making it a familiar sight from the Aleutians to le Shima, from Newfoundland to England – and into the industrial core of Third Reich Germany.
On these missions, from flying cargo to dropping bombs, the B- 24 proved itself a tough and sturdy bird. Its best bombing altitudes lay between 12 and 20,000 ft. Its bombs were stacked vertically, in two main bays, and the shape of the deep fuselage gave the bird a dumpy, boxcar look, but it also provided a roomy flight deck on which you could stand up and move around after hours at the controls. Able to absorb punishment the B-24 could stay in the air despite the holes in it, as long as it had power and control. From a total of five hand-held .50 caliber machine guns on the early D models, the Liberator featured ten .50s when the D was phased out.
Sluggish above 24,000 ft. the B-24 made airplane drivers out of the majority of its pilots and it took almost 100 hours in the bird to master its idiosyncrasies. The most dangerous of all was its high wing loading which made for high speed, or secondary stalls. You just didn’t pull too many gs in the B-24, primarily because it was too underpowered for the Davis Wing. When originally designed, the 1,200 hp. Pratt & Whitneys may have been sufficient, but as guns, armor plate, turrets and increased bomb loads were added, the engines couldn’t pull the big pug-nosed bomber through the air fast enough and when the bomb doors were opened, the aircraft just stopped flying. It literally mushed through the air.
Yet despite its awkward characteristics, it held together well during crash landings, as long as the wheels were retracted, otherwise its back would break, and although not known for its low-level capabilities, it was the plane that carried out the most daring low-level mission of the war, the legendary Ploesti raid.
Yet, no matter what the B-24’s drawbacks, it was definitely a workhorse. It made the long, back-breaking twelve hour · trips over the Alps to Munich, Vienna, Brux and other places, carrying men to bomb targets in towns that they had never heard of before and never would again. In cold that reached 52 degrees below zero, through flak-filled skies, men of the 15th Air Force, their gross weights conveniently forgotten, defied the law of gravity again and again, as they did in the Pacific, island hopping from one chain to the next, reaching out for the heartland of Japan. Many were last to fighters, others were blown apart by the giant concentration of flak batteries below, still others would succumb to a loose gas cap which allowed fuel to siphon out of the wing tanks in flight. The entire after end of the Liberator would be sprayed with gasoline, a potent mist of it permeating the fuselage, entering through the waist windows. One spark and boom. The price of high speed, long range and large capacity as propagated by Davis and brought to fruition by designer Issac M. Laddon, was tough flying characteristics, but once a pilot recognized the B- 24’s shortcomings and monitored them, he no longer drove a lumbering cargo container, but had an effective flying machine on his hands.