COMMENT: The aircraft B-29 Superfortress (Model number B-29-45-MO, Serial number 44-86292, Victor number # 12, (squadron-assigned identification)) – later known as Enola Gay – was built by the Glenn L. Martin Company at its bomber plant in Bellevue, Nebraska. The bomber was one of the first fifteen B-29s built to the “Silverplate” specification— of 65 eventually completed during and after World War II—giving them the primary ability to function as nuclear “weapon delivery” aircraft. These modifications included an extensively modified bomb bay with pneumatic doors and British bomb attachment and release systems, reversible pitch propellers that gave more braking power on landing, improved engines with fuel injection and better cooling, and the removal of protective armor and gun turrets.
The aircraft was personally selected by Colonel Paul W. Tibbets Jr., the commander of the 509th Composite Group, on 9 May 1945, while still on the assembly line. The aircraft was accepted by the United States Army Air Force (USAAF) on 18 May 1945 and assigned to the 393rd Bombardment Squadron, Heavy, 509th Composite Group. The tail marking was a circle outline around an arrowhead pointing forward. The Crew B-9, commanded by Captain Robert A. Lewis, took delivery of the bomber and flew it from Omaha to the 509th base at Wendover Army Air Field, Utah, on 14 June 1945.
Thirteen days later, the aircraft left Wendover for Guam, where it received a bomb-bay modification, and flew to North Field, Tinian, on 6 July. It was initially given the Victor number # 12, but on 1 August, the tail marking of the 509th Composite Group, circle outline around an arrowhead pointing forward, was changed in circle R tail marking of the 6th Bombardment Group, 313th Bomb Wing, as a security measure and had its Victor number changed to # 82 to avoid misidentification with actual 6th Bombardment Group aircraft.
During July, the bomber made eight practice or training flights and flew two missions, on 24 and 26 July, to drop pumpkin bombs on industrial targets at Kobe and Nagoya. Enola Gay was used on 31 July on a rehearsal flight for the actual mission (Ref. 24).
Comment: On 5 August 1945, the Strike Order 35 was given to deliver the first atomic bomb Little Boy the next day on 6 August. This order not only gives the detailed time scale of the pre-flight preparations but also the Victor (identifications) number s of all aicraft involved in the attack as well as the names of the aircraft‘s commanding officers. The combat strike consisted of four aircraft with one alternative plane and four weather mission aircraft including one alternative aircraft . Weather Ships had to start at 0200 ET, while the Combat Ships followed one hour later. Victor # 82 was the Enola Gay with Col. Tibbets at the controlls.
ATOMIC BOMB „LITTLE BOY“
Little Boy was 300 cm in length, 71 cm in diameter and weighed approximately 4,400 kg. The design used the gun method to explosively force a hollow sub-critical mass of enriched uranium and a solid target cylinder together into a super-critical mass, initiating a nuclear chain reaction. This was accomplished by shooting one piece of the uranium onto the other by means of four cylindrical silk bags of cordite powder.
The bomb contained 64 kilograms of enriched uranium. Most was enriched to 89% but some was only 50% uranium-235, for an average enrichment of 80%. Less than a kilogram of uranium underwent nuclear fission, and of this mass only 0.7 grams was transformed into several forms of energy, mostly kinetic energy, but also heat and radiation. The bomb had an explosive force of about 20,000 tons of TNT, about the same as the Fat Man bomb dropped on Nagasaki .
The Little Boy pre-assemblies were designated L-1, L-2, L-3, L-4, L-5, L-6, L-7 and L-11. L-1, L-2, L-5 and L-6 were expended in test drops. L-6 was used in the Iwo Jima dress rehearsal on 29 July. This was repeated on 31 July, but this time L-6 was test dropped near Tinian by Enola Gay. Finally, L-11 was the assembly used for the Hiroshima bomb.
STRIKE ON HIROSHIMA, DATE: AUGUST, 6th, 1945
During preparation for the first atomic mission, Tibbets assumed command of the aircraft and named it after his mother, Enola Gay Tibbets, who, in turn, had been named for the heroine of a novel. In the early morning hours, just prior to the 6 August mission, Tibbets had a young Army Air Forces maintenance man, Private Nelson Miller, paint the name just under the pilot’s window. Except for Enola Gay, none of the 509th Composite Group B-29s had yet had names painted on the noses. All other names were given after the mission.
Hiroshima was the primary target of the first nuclear bombing mission on 6 August, with Kokura and Nagasaki as alternative targets. Enola Gay, piloted by Tibbets, took off from North Field, in the Northern Mariana Islands, about six hours’ flight time from Japan, accompanied by two other B-29s, The Great Artiste, piloted by Major Charles W. Sweeney carrying instrumentation, and a then-nameless aircraft later called Necessary Evil, commanded by Captain George Marquardt, to take photographs
After leaving Tinian, the three aircraft made their way separately to Iwo Jima, where they rendezvoused at 8,010 ft and set course for Japan. The aircraft arrived over the target in clear visibility at 32,333 ft. Navy Captain William S. Parsons of Project Alberta, who was in command of the mission, armed the bomb during the flight to minimize the risks during takeoff. His assistant, Second Lieutenant Morris R. Jeppson, removed the safety devices 30 minutes before reaching the target area.
The release at 08:15 (Hiroshima time) went as planned, and the Little Boy took 53 seconds to fall from the aircraft flying at 31,060 feet to the predetermined detonation height about 1,968 feet above the city. Enola Gay traveled 11.5 mi before it felt the shock waves from the blast. Although buffeted by the shock, neither Enola Gaynor The Great Artiste was damaged. Enola Gay returned safely to its base on Tinian to great fanfare, touching down at 2:58 pm, after 12 hours 13 minutes. The Great Artiste and Necessary Evil followed at short intervals. Several hundred people, including journalists and photographers, had gathered to watch the planes return. Tibbets was the first to disembark and was presented with the Distinguished Service Cross on the spot (Ref.: 24).
Comment: After the Hiroshima Mission the Enola Gay‘s circle R tail marking of the 6th Bombardment Group, 313th Bomb Wing tail marking was changed to that of the 509th Composite Group, circle outline around an arrowhead pointing forward. The Victor # 82 remained unchanged, Additional First Atomic Bomb Hiroshima – August 6/1945 was painted on starboard side of Enola Gay.
After the war, the Enola Gay returned to the United States, where it was operated from Roswell Army Air Field, New Mexico. In May 1946, it was flown to Kwajalein, Marshall Islands, for the Operation Crossroads nuclear tests in the Pacific, but was not chosen to make the test drop at Bikini Atoll.
Since 2003, the entire restored Boeing B-29 Enola Gay has been on display at National Air and Space Museums’s Steven Udvar-Hazy Center, Chantilly, Fairfax County, Virginia.
Plans for more atomic attacks on Japan
Major General Leslie R. Groves expected to have another Fat Man atomic bomb ready for use on 19 August, with three more in September and a further three in October; a second Little Boy bomb (using U-235) would not be available until December 1945. On 10 August, he sent a memorandum to General of the Army Georg C. Marshall in which he wrote that “the next bomb … should be ready for delivery on the first suitable weather after 17 or 18 August.” Marshall endorsed the memo with the hand-written comment, “It is not to be released over Japan without express authority from the President”, something President Harry S. Truman had requested that day. This modified the previous order that the target cities were to be attacked with atomic bombs “as made ready”. There was already discussion in the War Department about conserving the bombs then in production for Operation Downfall (proposed Allied plan for the invasion of the Japanese home islands near the end of World War II), and Marshall suggested to Secretary of War Henry L. Stimson that the remaining cities on the target list be spared attack with atomic bombs.
Two more Fat Man assemblies were readied, and scheduled to leave Kirtland Field, New Mexico, for Tinian on 11 and 14 August, and Tibbets was ordered by Major General Curtis LeMay to return to Albuquerque, New Mexico, to collect them. At Los Alamos, New Mexico, technicians worked 24 hours straight to cast another plutonium core. Although cast, it still needed to be pressed and coated, which would take until 16 August. Therefore, it could have been ready for use on 19 August. Unable to reach Marshall, Groves ordered on his own authority on 13 August that the core should not be shipped.
On Marshall’s orders, Major General John E. Hull looked into the tactical use of nuclear weapons for the invasion of the Japanese home islands, even after the dropping of two strategic atomic bombs on Japan (Marshall did not think that the Japanese would capitulate immediately). Colonel Lyle E. Seeman reported that at least seven Fat Man-type plutonium implosion bombs would be available by X-Day, which could be dropped on defending forces. Seeman advised that American troops not enter an area hit by a bomb for “at least 48 hours”; the risk of nuclear fallout was not well understood, and such a short time after detonation would have exposed American troops to substantial radiation.
Ken Nicols, the District Engineer of the Manhattan Engineer District, wrote that at the beginning of August 1945, “planning for the invasion of the main Japanese home islands had reached its final stages, and if the landings actually took place, we might supply about fifteen atomic bombs to support the troops.” An air burst 1,800–2,000 ft above the ground had been chosen for the (Hiroshima) bomb to achieve maximum blast effects, and to minimize residual radiation on the ground, as it was hoped that American troops would soon occupy the city (Ref.: 24).
POWER PLANT: Four Wright R-3350-23 Duplex-Cyclone air-cooled turbocharged radial piston engines, 2,200 hp each
PERFORMANCE: 357 mp
COMMENT: The Boeing B-29 Superfortress was an American four-engined propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the Boeing B-17 Flying Fortress, the Superfortress was designed for high-altitude strategic bombing, but also excelled in low-altitude night incendiary bombing, and in dropping naval mines to blockade Japan. B-29s dropped the atomic bombs on Hiroshima and Nagasaki, the only aircraft ever to drop nuclear weapons in combat.
One of the largest aircraft of World War II, the B-29 was designed with state-of-the-art technology, which included a pressurized cabin, dual-wheeled tricycle landing gear, and an analog computer-controlled fire-control system that allowed one gunner and a fire-control officer to direct four remote machine gun turrets. The $3 billion cost of design and production, far exceeding the $1.9 billion cost of the Manhattan Project (development oft he atomic bomb), made the B-29 program the most expensive of the war. The B-29 remained in service in various roles throughout the 1950s, being retired in the early 1960s after 3,970 had been built.
Before World War II, the United States Army Air Force (USAAF) concluded that the Boeing B-17 Flying Fortress, which would be the Americans’ primary strategic bomber during the war, would be inadequate for the Pacific Theater, which required a bomber that could carry a larger payload more than 3,000 miles
In response, Boeing began work on pressurized long-range bombers in 1938. Boeing’s design study for the Model 334 was a pressurized derivative of the Boeing B-17 Flying Fortress with nosewheel undercarriage. Although the Air Corps lacked funds to pursue the design, Boeing continued development with its own funds as a private venture. In April 1939, Charles Lindberg convinced General Henry H. Arnold to produce a new bomber in large numbers to counter the Germans’ bomber production. In December 1939, the Air Corps issued a formal specification for a so-called “superbomber” that could deliver 20,000 lb of bombs to a target 2,667 mi away, and at a speed of 400 mph. Boeing’s previous private venture studies formed the starting point for its response to the Air Corps formal specification.
Boeing submitted its Model 345 on May 1940, in competition with designs from Consolidated Aircraft Model 33, which later became the Convair B-32 Dominator, Lockheed XB-30 and Douglas XB-31 Raidmaster. Douglas and Lockheed soon abandoned work on their projects, but Boeing received an order for two flying prototypes, which were given the designation XB-29, and an airframe for static testing on August 1940, with the order being revised to add a third flying aircraft on December. Consolidated continued to work on its Model 33, as it was seen by the Air Corps as a backup if there were problems with Boeing’s design. Boeing received an initial production order for 14 service test aircraft and 250 production bombers in May 1941, this being increased to 500 aircraft in January 1942. The B-29 featured a fuselage design with circular cross-section for strength. The need for pressurization in the cockpit area also led to the B-29 being one of very few American combat aircraft of World War II to have a stepless cockpit design, without a separate windscreen for the pilots.
Manufacturing the B-29 was a complex task that involved four main-assembly factories. Thousands of subcontractors were also involved in the project. The first prototype made its maiden flight on September 1942. The combined effects of the aircraft’s highly advanced design, challenging requirements, immense pressure for production, and hurried development caused setbacks. Unlike the unarmed first prototype, the second was fitted with a Sperry defensive armament system using remote-controlled gun turrets sighted by periscopes and first flew on December 1942, although the flight was terminated due to a serious engine fire.
On February 1943, the second prototype experienced an engine fire and crashed. Changes to the production craft came so often and so fast that, in early 1944, B-29s flew from the production lines directly to modification depots for extensive rebuilds to incorporate the latest changes. USAAF-contracted modification centers and its own air depot system struggled to handle the scope of the requirements. By the end of 1943, although almost 100 aircraft had been delivered, only 15 were airworthy. This prompted an intervention by General Hap Arnold to resolve the problem, with production personnel being sent from the factories to the modification centers to speed availability of sufficient aircraft to equip the first bomb groups in what became known as the “Battle of Kansas”. This resulted in 150 aircraft being modified in the five weeks, between March and April 1944.
The most common cause of maintenance headaches and catastrophic failures was the engines. Although the Wright R-3350 Duplex Cyclone radials later became a trustworthy workhorse in large piston-engined aircraft, early models were beset with dangerous reliability problems.
In wartime, the B-29 was capable of flight at altitudes up to 31,850 feet at speeds of up to 350 mph (true air speed)). This was its best defense because Japanese fighters could barely reach that altitude, and few could catch the B-29 even if they did attain that altitude.
The General Electric Central Fire Control system on the B-29 directed four remotely controlled turrets armed with two .50 Browning M2 machine guns each. All weapons were aimed optically, with targeting computed by analog electrical instrumentation. There were five interconnected sighting stations located in the nose and tail positions and three Plexiglas blisters in the central fuselage. Five General Electric analog computers (one dedicated to each sight) increased the weapons’ accuracy by compensating for factors such as airspeed, lead, gravity, temperature and humidity. The computers also allowed a single gunner to operate two or more turrets (including tail guns) simultaneously. The gunner in the upper position acted as fire control officer, managing the distribution of turrets among the other gunners during combat. The tail position initially had two .50 Browning machine guns and a single M2 20 mm cannon. Later aircraft had the 20 mm cannon removed, sometimes replaced by a third machine gun.
The crew would enjoy, for the first time in a bomber, full-pressurization comfort. This first-ever cabin pressure system for an Allied production bomber was developed for the B-29 by Garrett AiResearck and a long tunnel joining the forward and rear crew compartments. Crews could use the tunnel if necessary to crawl from one pressurized compartment to the other.
In early 1945, Major General Curtiss LeMay, commander of XXI Bomber Command—the Marianas-based B-29-equipped bombing force—ordered most of the defensive armament and remote-controlled sighting equipment removed from the B-29s under his command. The affected aircraft had the same reduced defensive firepower as the nuclear weapons-delivery intended Silverplate B-29 airframes and could carry greater fuel and bomb loads as a result of the change. The lighter defensive armament was made possible by a change in mission from high-altitude, daylight bombing with high explosive bombs to low-altitude night raids using incendiary bombs. As a consequence of that requirement, Bell Atlanta (BA) produced a series of 311 B-29Bs that had turrets and sighting equipment omitted, except for the tail position, which was fitted with AN/APG-15 fire-control radar. That version could also have an improved APQ-7 “Eagle” bombing-through-overcast radar fitted in an airfoil-shaped radome under the fuselage. Most of those aircraft were assigned to the 315th Bomb Wing, Northwest Field, Guam.
In September 1941, the USAAF’ plans for war against Germany and Japan proposed basing the B-29 in Egypt for operations against Germany, as British airbases were likely to be overcrowded. By the end of 1943, plans had changed, partly due to production delays, and the B-29 was dedicated to the Pacific Theater. A new plan implemented deployed the B-29 units to attack Japan from four forward bases in southern Cina, with five main bases in India, and to attack other targets in the region from China and India as needed. The XX Bomber Command, initially intended to be two combat wings of four groups each, was reduced to a single wing of four groups because of the lack of availability of aircraft, automatically limiting the effectiveness of any attacks from China.
This was an extremely costly scheme, as there was no overland connection available between India and China, and all supplies had to be flown over the Himalayas, either by transport aircraft or by B-29s themselves, with some aircraft being stripped of armor and guns and used to deliver fuel.
The solution to this problem was to capture the Mariana Islands, which would bring targets such as Tokyo, about 1,500 mi north of the Marianas within range of B-29 attacks. The Joint Chiefs of Staff agreed in December 1943 to seize the Marianas.
US forces invaded Saipan on 15 June 1944 what was secured by 9 July. Operations followed against Guam and Tinian, with all three islands secured by August.
Naval construction battalions (Seabees) began at once to construct air bases suitable for the B-29, commencing even before the end of ground fighting. In all, five major airfields were built: two on the flat island of Tinian, one on Saipan, and two on Guam. Each was large enough to eventually accommodate a bomb wing consisting of four bomb groups, giving a total of 180 B-29s per airfield. These bases could be supplied by ship and, unlike the bases in China, were not vulnerable to attack by Japanese ground forces. The bases became the launch sites for the large B-29 raids against Japan in the final year of the warand the first combat mission was launched from there on 28 October 1944, with 14 B-29s, the first attack on the Japanese capital since the Doolittle Raid in April 1942.
Boeing B-29A Superfortress “Rattle N’ Roll” showed here belonged to the 6th Bomber Group, 313th Bomb Wing, XXth USAAF, stationed at North Field, Tinian, Marianas
The most famous B-29s were the Silverplate series. These aircraft were extensively modified to carry nuclear weapons. Serious consideration was given to using the British Lancaster bomber, as this would require less modification. The most significant modification was the enlargement of the bomb bay enabling each aircraft to carry either the “Little Boy”, an enriched uranium gun-type fission weapon or “Fat Man”, a plutonium implosion-type nuclear weapon.
Little Boy was dropped on Hiroshima on 6 August 1945 by B-29 Enola Gay, flown by Colonel Paul W. Tibbets Jr and the Fat Man was dropped on Nagasaki on 9 August 1945 by B-29 Bockscar, flown by Mayor Charles W. Sweeney.
Japan surrendered to the Allies on 15 August, six days after the bombing of Nagasaki and effectively ended World War II (Ref.: 24).
POWER PLANT: Four Pratt & Whitney R-1830-43 Twin Wasp radial engines, rated at 1,200 hp each
PERFORMANCE: 303 mph at 25,000 ft
COMMENT: The Consolidated B-24 Liberator was an American heavy bomber, designed by Consolidated Aircraft of San Diego, California. It was known within the company as the Model 32, and some initial production aircraft were laid down as export models designated as various LB-30s, in the Land Bomber design category.
The B-24 was used extensively in WW II. It served in every branch of the American armed forces as well as several Allied air forces and navies. It saw use in every theater of operations. Along with the Boeing B-17 Flying Fortress, the B-24 was the mainstay of the US strategic bombing campaign in the Western European theater. Due to its range, it proved useful in bombing operations in the Pacific Area, including the bombing of Japan. Long-range anti-submarine Liberators played an instrumental role in closing the Mid-Atlantic gap in the Battle oft he Atlantic.
The Consolidated B-24D Liberator was the first mass-produced series. The B-24D was the Liberator III in British service. It entered US service in early 1942. It had turbocharged engines and increased fuel capacity. Three more 12.7 mm machine guns brought the defensive armament up to 10 machine guns. At 27,000 kg (29.76 short tons) maximum takeoff weight, it was one of the heaviest aircraft in the world.
First model produced on a large scale; ordered from 1940 to 1942, as a Consolidated B-24C with better Pratt & Whitney R-1830-43 supercharged engines. The B-24D model was initially equipped with a remotely operated and periscopically sighted Bendix belly turret, as the first examples of the Boeing B-17E Flying Fortress and some early models of the North American B-25 Mitchell medium bomber had used, but this proved unsatisfactory in service and was discontinued after the 287th aircraft. Production aircraft reverted to the earlier manually operated “tunnel” mounting with a single 12.7 mm machine. The tunnel gun was eventually replaced by the Sperry ball turret, which had also been adopted by the later Boeing B-17E Fortresses, but made retractable for the Liberator when not in use as the ventral area of its fuselage was very close to the ground on landing. In late B-24Ds, “cheek” guns mounted on either side of the forward nose, just behind the framed “greenhouse” nose glazing were added.
Between 1940 and 1945 in total 18,188 B-24 of various subtypes had been built, The number of B-24D Liberator amounted 2,696 aircraft, of which 2,381 planes were built by Consolidated, San Diego, 305 planes by Consolidated, Fort Worth, and 10 examples by Douglas, Tulsa, Oklahoma.
The Consolidated B-24D Liberator shown here, BuAer # 41-24215, was originally an aircraft of the 409th BS, 93rd BG, 8th AF in Europe and named ‘Lucky Gordon’, sometimes called just ‘Lucky’. On Aug 01th, 1943 the aircraft took part in the Ploesti oil refinery raid, diverting to Sicily, Italy. After returning to the European Theatre of Operations (ETO) and further missions it was declared war weary and renamed ‘Dogpatch Raider’ and served with the 703rd BS, as a high visibility assembly ship for the 445th BG (H), flying from RAF Tibenham, Norfolk. The large letter “F” on her fuselage, the Group’s call letter, contained bright navigation lights for dim lighting conditions (Ref.: 24).
POWER PLANT: Four Wright R-1820-97 “Cyclone” turbo-supercharged radial engines, rated at 1,200 hp each
PERFORMANCE: 300 mph at 30,000 ft
COMMENT: The Boeing B-17 Flying Fortress is a four-engine heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). From its introduction in 1938, the B-17 Flying Fortress evolved through numerous design advances becoming the third-most produced bomber of all time, behind the four-engine Consolidated B-24 Liberator and the multirole, twin-engine Junkers Ju 88,
The Boeing B-17 began operations in World War II with the Royal Air Force (RAF) in 1941, and in the Southwest Pacific with the U.S. Army. In July 1942, the first USAAF Boeing B-17Fs were sent to England to join the Eighth Air Force. Later that year, two groups moved to Algeria to join Twelfth Air Force for operations in North Africa. The B-17Fs were primarily involved in the daylight precision strategic bombing campaign against German targets ranging from U-boat pens, docks, warehouses, and airfields to industrial targets such as aircraft factories. In the campaign against German aircraft forces in preparation for the invasion of France, B-17 and B-24 raids were directed against German aircraft production while their presence drew the Luftwaffe fighters into battle with Allied fighters.
Soon, Boeing B-17Fs proved to be unsuitable for combat use over Europe. The defense expected from bombers operating in close formation alone did not prove effective and the bombers needed fighter escorts to operate successfully. Especially the head-on attacks of German fighters were dangerous, To improve defense a modification in form of a power-operated Bendix “chin” turret mounting two 0.5-in. machine guns was introduced in the last production model, the Boeing B-17G. With the two “cheek” guns and the “chin” turret the protection against incoming fighters was increased enormously. In order to improve the field of fire to the rear a so-called “Cheyenne” tail gun mounting was fitted bringing the total number of guns from seven (B-17F) to 13 (B-17G). Incorporating all changes made to its predecessor, in total 8,680 B-17Gs were built, the last (by Lockheed) on July1945.
During World War II, the B-17 equipped 32 overseas combat groups, inventory peaking in August 1944 at 4,574 USAAF aircraft worldwide (Ref.: 24).
The aircraft shown here belonged to the 486th Bombardment Group (H), 832BS (Bombardment Squadron) stationed at Sudbury, UK. All B-17Gs were in natural metal. Group markings: W in square. In late 1944 red and blue bands forming chevron were painted on wing with blue band towards tip. From January 1945 wing tips and complete tail section painted yellow and three parallel bands of yellow round rear fuselage. In place nose bands and aircraft letter on fuselage (forward national insignia) in squadron color: 832BS in yellow, 833BS in medium blue, 834BS in red, and 835BS in bright green (Ref.: 2).
POWER PLANT: Four Wright R-1820-97 Cyclone supercharged radial engines, rated at 1,200 hp each
PERFORMANCE: 287 mph
COMMENT: The Boeing B-17 “Flying Fortress” was a four-engine heavy bomber developed in the 1930s for the United States Army Air Corps (USAAC). Competing against Douglas and Martin for a contract to build 200 bombers, the Boeing entry (prototype Model 299, XB-17) outperformed both competitors and exceeded the air corps’ performance specifications. Although Boeing lost the contract (to the Douglas B-18 “Bolo”) because the prototype crashed, the air corps ordered 13 more B-17s for further evaluation. From its introduction in 1938, the B-17 “Flying Fortress” evolved through numerous design advances becoming the third-most produced bomber of all time, behind the American four-engined Consolidated B-24 “Liberator” and the German multirole, twin-engined Junkers Ju 88.
On 8 August 1934, the USAAC tendered a proposal for a multiengine bomber to replace the Martin B-10. The Air Corps was looking for a bomber capable of reinforcing the air forces in Hawaii, Panama, and Alaska. Requirements were for it to carry a “useful bombload” at an altitude of 10,000 ft, a range of 2,000 mi and a top speed of at least 250 mph was desired.
The prototype XB-17, with the Boeing factory designation of Model 299, was built at Boeing’s own expense. It combined features of the company’s experimental XB-15 bomber and Model 247 transport. The first flight of the Model 299 was on July 1935 and on 20 August 1935, the prototype flew from Seattle to Wright Field in nine hours and three minutes with an average cruising speed of 252 miles per hour, much faster than the competition.
The USAAC had been impressed by the prototype’s performance, and on January 1936, through a legal loophole, the air corps ordered 13 YB-17s (designated Y1B-17 after November 1936 to denote its special F-1 funding) for service testing.
The YB-17 incorporated a number of significant changes from the Model 299, including more powerful Wright R-1820-39 Cyclone engines. Although the prototype was company-owned and never received a military serial (the B-17 designation itself did not appear officially until January 1936, nearly three months after the prototype crashed), the term “XB-17” was retroactively applied to the airframe and has entered the lexicon to describe the first “Flying Fortress”.
Opposition to the air corps’ ambitions for the acquisition of more B-17s faded, and in late 1937, 10 more aircraft designated B-17B were ordered to equip two bombardment groups, one on each U.S. coast. Improved with larger flaps and rudder and a well-framed, 10-panel plexiglas nose, the B-17Bs were delivered in five small batches between July 1939 and March 1940. In July 1940, an order for 512 B-17s was issued, but at the time of the attack on Pearl Harbor, fewer than 200 were in service with the army.
The aircraft went through several alterations in each of its design stages and variants. Of the 13 YB-17s ordered for service testing, 12 were used by the 2nd Bomb Group of Langley Field, Virginia, to develop heavy bombing techniques, and the 13th was used for flight testing at the Material Division at Wright Field, Ohio. Experiments on this aircraft led to the use of a quartet of General Electric turbo-superchargers which would become standard on the B-17 line
As the production line developed, Boeing engineers continued to improve upon the basic design. To enhance performance at slower speeds, the B-17B was altered to include larger rudders and flaps. The B-17C changed from three bulged, oval-shaped machine gun blisters to two flush, oval-shaped machine gun window openings, and on the lower fuselage, a single “bathtub” machine gun gondola housing, which resembled the similarly configured and located ventral defensive emplacement on the German Heinkel He 111P-series medium bomber.
While models A through D of the B-17 were designed defensively, the large-tailed B-17E was the first model primarily focused on offensive warfare. The B-17E was an extensive revision of the Model 299 design: The fuselage was extended by 10 ft; a much larger rear fuselage, vertical tailfin, rudder, and horizontal stabilizer were added to the design; a gunner’s position was added in the new tail; the nose (especially the bombardier’s well-framed, 10-panel nose glazing) remained relatively the same as the earlier B through D versions had, but with the addition of a Sperry electrically powered manned dorsal gun turret just behind the cockpit, and the similarly powered Sperry-built manned ventral ball turret just aft of the bomb bay. The B-17’s turbocharged Wright R-1820 Cyclone 9 engines were upgraded to increasingly more powerful versions of the same power plants multiple times throughout its production, and similarly, the number of machine gun emplacement locations was increased to enhance the aircraft’s combat effectiveness.
In April 1942, the B-17F was introduced onto the production lines, and outwardly this variant differed from the B-17E only in having an extended Plexiglas nose which was frameless except for the optically flat bomb-aiming panel, paddle-blade airscrews for maximum operating performance, extra fuel cells, improvements of the bomb stowage, brake system, communications equipment and oxygen system. As the cross weight was increased, the undercarriage was strengthened.
Owing to the constant modifications being applied to aircraft on the production lines and the immense scale of production orders, a system of “Block Designations” was instituted. Thus, the first Boeing-built B-17F Fortress became B-17F-1-BO, and all aircraft in this production block were identical insofar as equipment and installations were concerned. Blocks B-17F-5-BO, -10-BO, etc., followed, the intervening number being left to indicate subsequent changes made at modification centres. Production of the B-17F continued for 15 months, during which 2,300 were built by Boeing, 600 by Douglas (suffix DL) and 500 by Locked Vega (suffix VE). The final production blocks of the B-17F from Douglas’ plants did, however, adopt the Bendix “chin turret” with two machine guns, giving them a much-improved forward defense capability.
The B-17F variants were the primary versions flying for the Eighth Air Force to face the Germans in 1943. The maximum bomb load of the first B-17F was 4.350 kg, but on typical missions to Germany, Eighth Air Force Fortresses carried 1.800- 2.270 kg over operating ranges averaging 1,400 miles. Beyond these distances, the bomb load fell rapidly, so that the effective combat radius of B-17F was about a maximum of 800 miles. Later modifications already referred to increase the fuel capacity as well as bomb load and by that the USAAF was enabled to build up an immense striking force in the European Theatre of Operations (Ref.: 4, 24).
POWER PLANT: Four Pratt & Whitney R-1830-43 Twin Wasp radial engines, rated at 1,200 hp each
PERFORMANCE: 303 mph at 25,000 ft
COMMENT: The Consolidated B-24 “Liberator was a heavy long-range bomber of the USAAF during WW II and large aircraft for its day. It had a wing span of 110 feet and a gross weight of more than 30 tons. Powered by four 1,200 hp radial engines, it had a maximum fuel capacity of 2,814 US gallons and the bomb load varied from 2,000 to 4,000 kp depending on the distance of the target to be attacked. The crew varied from eight to 10 men, five or six of whom acted as gunners, manning the 10 machine guns usually carried for defence.
The operating technique with these heavy bombers was, after take-off, to assemble large formations of from 20 to 40 aircraft while climbing to operational altitude of 20,000 to 25,000 feet. This was coordinated by means of “Assembly Ships” (or “Formation Ships”) specially fitted to aid assembly of individual group formations. They were equipped with signal lighting, provision for quantity discharge of pyrotechnics, and were painted with distinctive group-specific high-contrast patterns of stripes, checkers or polka dots to enable easy recognition by their flock of bombers. The aircraft used in most cases were veteran B-24Ds. All armament and armor was removed and arrangements for signal lighting varied from group to group, but generally consisted of white flashing lamps on both sides of the fuselage arranged to form the identification letter of the group. Such an assembly was despatched from a single airfield and joined with other formations to form a division column of perhaps 500 to 600 bombers.
The 446th Bombardment Group (H) with Component Squadrons 784th, 785th, 786th and 787th Bombardment Squadron (H) was activated on 1 Aug. 1943 at Alamogordo AAFd. NM. The training for combat commenced at Kearns Fd. Utah end Aug. 43, remaining there until Nov, 43, when the group moved back to Alamogordo AAFd, NM. In early Feb. 44 the group moved to Topeka AAFd, Kan and after a week’s stay began movement to the UK. Here the group was stationed at Attlebridge, Norfolk, for the last year of the war in Europe.
Combat aircraft were Consolidated B-24H, B-24J, B-24L and B-24M. In total the group flew 232 missions in the course of the year against strategic objectives like U-boat installations in Kiel, ball bearing works in Berlin, aircraft factories in Munich and oil refineries in Hamburg. Remarkably, the 785th Bomb Squadron flew 55 consecutive missions without loss. The aircraft shown here is the assembly ship of the 446th Bombardment Group. It’s a veteran Consolidated B-24D named “Striped Ass” (Ref: 2).
Notice: Identification markings of this aircraft are mostly hand-made. After airbrushing the surface with different aluminum-silver shading red stripes are applied according to the original. For this I used microthin precision slit tape, Bishop Graphics. Inc., Westlake Village, Ca. This is self-adhesive, in red color, extreme thin and easy to apply. Unfortunately transparent it needed to be painted stripe by stripe before being applied.
TYPE: Heavy long-range bomber, in service as Assembly ship
ACCOMMODATION: Crew of five to six
POWER PLANT: Four Pratt & Whitney R-1830-35 turbocharged “Twin-Wasp” radial engines, rated at 1.200 hp each
PERFORMANCE: 290 mph
COMMENT: In February 1944, the 2nd Division of the Eight Army Air Force in Europe authorized the use of “Assembly Ships” (or “Formation Ships”) specially fitted to aid assembly of individual group formations. They were equipped with signal lighting, provision for quantity discharge of pyrotechnics, and were painted with distinctive group-specific high-contrast patterns of stripes, checkers or polka dots to enable easy recognition by their flock of bombers. The aircraft used in the first allocation were B-24Ds retired by the 44th, 93rd and 389th Groups. Arrangements for signal lighting varied from group to group, but generally consisted of white flashing lamps on both sides of the fuselage arranged to form the identification letter of the group. All armament and armor was removed and in some cases the tail turret. In the B-24Hs used for this purpose, the nose turret was removed and replaced by a “carpetbagger” type nose. Following incidents when flare guns were accidentally discharged inside the rear fuselage, some assembly (formation) ships had pyrotechnic guns fixed through the fuselage sides. As these aircraft normally returned to base once a formation had been established, a skeleton crew of two pilots, navigator, radio operator and one or two flare discharge operators were carried. In some groups an observer officer flew in the tail position to monitor the formation. These aircraft became known as „”Judas goats“ (Ref: 24).
The Consolidated B-24D “Liberator”, 41-23683 “Green Dragon” shown here is an assembly (formation-) ship of the 458th Bombardment Group (H) “The Sky Scorpions”, 8th USAAF, stationed at Hethel, UK from 1943 to 1945 (Ref.: 2)
TYPE: Heavy long-range bomber, in service as Assembly ship
ACCOMMODATION: Crew of four
POWER PLANT: Four Pratt & Whitney R-1830-43 Twin Wasp radial engines, rated at 1,200 hp each
PERFORMANCE: 303 mph at 25,000 ft
COMMENT: The Consolidated B-24D “Liberator” was the first variant to be qualified for combat. Under the original Production Pool plan, Consolidated/San Diego was the prime manufacturer, supplying components to Fort Worth and Douglas/Tulsa for assembly. In May, 1942 the first of 2,738 B-24D’s rolled off the assembly lines.
Due to rapidly changing needs, especially for defensive armament, there were many variations within the B-24D model, these differences identified by “production blocks” (e.g B-24D-70-CO). Nevertheless, B-24D’s have been very successful in the first years of bombing offensive in the European theater but later are replaced by B-24H and B-24J. These variants had more powerful engines and better defensive armament. Some bombardment groups used phased-out B-24Ds as assembly (formation) ships until the end of the hostilities. The B-24D Assembly (Formation) Ship “The Little Gramper” shown here belonged to the 491th Bombardment Group (H) „The Ringmasters“, stationed at North Pickenham. (Ref. 2)
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