The B-29 bomber, produced by the Boeing Aircraft Company during the war, was the first long-range heavy bomber employed by the United States. It was primarily used in the war's Pacific Theater, and became notorious as the plane used to drop the world's first atomic bombs on the cities of Hiroshima and Nagasaki, Japan, Aug. 6 and 9, 1945.
The Boeing B-29 was designed in 1940 as an eventual replacement for the B-17 and B-24. The first one built made its maiden flight on Sept. 21, 1942. Developing the Boeing B-29 was a program which rivaled the Manhattan Project in size and expense. Technically a generation ahead of all other heavy bomber types in World War II, the Superfortress was pressurized for high altitudes and featured remotely-controlled gun turrets. Most important, its four supercharged Wright R-3350-23 engines gave it the range to carry large bomb loads across the vast reaches of the Pacific Ocean.
A test flight of the plane's XB-29 prototype ended in tragedy Feb. 18, 1943, when an engine caught fire and the plane crashed. The pilot, crew and 19 people on the ground were killed. The Boeing Company declared that it was "not going to build this airplane. It's no good. It has too many problems." Gen. Henry "Hap" Arnold, the Air Force's first general officer, argued with Boeing and threatened to force them to repay the $200 million that they had been given to build the planes. Faced with having to pay back money already received, Boeing agreed to "operate the factories," but they would "not take any responsibility for the airplane." The Army took over the test program after the crash. Development continued that summer with flight testing of the YB-29 even as hurried production versions of the B-29 were being turned out.
In December 1943, it was decided not to use the B-29 in the European Theater, thereby permitting the airplane to be sent to the Pacific area where its great range made it particularly suited for the long over water flight required to attack the Japanese homeland from bases in China. As it came into the AAF inventory in mid-1944, the B-29 weighed 140,000 pounds loaded, with an effective range of 3,250 miles. Pavements failed, and at their best, behaved erratically. No airfield pavement had been designed for more than 120,000 pounds gross weight. The Corps of Engineers began experiments anew with pavement overlays at Hamilton Field north of San Francisco.
Construction of the B-29 was thoroughly conventional. As standardized by Boeing and the aircraft industry during the pre World War II decade, the new bomber had an all metal fuselage with fabric covered control surfaces. On the other hand, and in spite of being a further development of the B-17, the B-29 was a radically different airplane, featuring significant aerodynamic innovations. Included were a high aspect ratio wing mid mounted on the circular section fuselage; huge Fowler flaps that increased the wing area by 19 percent when extended," and also raised the lift coefficient; a dual wheel retractable tricycle landing gear; flush riveting and butt jointing to reduce drag (the landing gear lowered contributed 50 percent of the resistance); and pressurized compartments for the usual crew of 10.
For defensive armament, the B-29 was equipped with non retractable turrets mounting ten .50 caliber machine guns and one 20 millimeter cannon (which was dropped from later models). All turrets were remotely operated by a General Electric central fire control system. The B-29 also had an extensive radio and radar equipment that included a liaison set, radio compass, marker beacon, glide path receiver, localizer receiver, IFF (identification friend or foe) transformer, emergency rescue transmitter, blind bombing radar (on many aircraft), radio countermeasures, and static dischargers.
Another special and for a while greatly troublesome feature of the B-29 was the brand new, but fire prone, 18 cylinder Wright R-3350-23 engine. The 4 engines were mounted by 4 bladed Hamilton constant speed, full feathering propellers, 16 feet, 7 inches in diameter. In addition, instead of the traditional single unit, each engine made use of 2 turbo superchargers.
As the powerful B-29 "Superfortress" rolled off America's production lines in the midst of World War II, General "Hap" Arnold, then Commanding General of the Army Air Forces, understood the need to bring the B-29's unique strategic bombing capabilities to bear against the Japanese homeland. Thus, in April 1944, he created Twentieth Air Force and gave it the daunting mission of conducting one of the largest--and ultimately most successful--air campaigns in history. Arnold's B-29s first flew in Operation MATTERHORN, which called for India-based Superfortresses to bomb Japan from forward bases in China. However, as allied forces advanced in the South Pacific "Island Hopping" campaign, Twentieth Air Force expanded its B-29 operations to bases in the Marianas Islands. During the last two months of 1944, B-29s began operating against Japan from the islands of Saipan, Guam and Tinian. Flying more than 1,500 miles one way, more than 1,000 bombers and 250 fighters conducted 28,000 combat sorties against Japan in the brief span of 16 months.
In early 1944 the Army Air Forces started its program to develop an atomic bomb delivery capability using the B-29 aircraft. The B-29 was the logical choice in view of its long range, superior high-altitude performance, and ability to carry an atomic bomb that was expected to weigh 9000 to 10,000 pounds. In March and again in June dummy atomic bombs were dropped by B-29s at Muroc Army Air Force Base in California to test the release mechanism. In August seventeen B-29s entered a modification program at the Glenn L. Martin plant in Omaha, Nebraska, to apply the lessons learned at Muroc. The "Silver Plate" project was the code name of the pilot and crew training program for the coming World War II atomic missions.
On 6 August 1945 the crew of the "Enola Gay" dropped the first atomic bomb on Hiroshima, Japan. The thirteen-hour mission to Hiroshima began at 0245 Tinian time. By the time they rendezvoused with their accompanying B-29s at 0607 over Iwo Jima, the group was three hours from the target area. The "Enola Gay" flew toward Hiroshima at a speed of 285 mph. After six-and-a-half hours of tough over-water navigation, the B-29 was over target within seventeen seconds of the scheduled drop time of 0915. When the 9,000-pound bomb "Little Boy" fell from the "Enola Gay," pilot Paul Tibbets put the aircraft into a 60-degree diving right turn and headed home. Seconds later, Hiroshima lie in ruins.
Despite widespread destruction, the Japanese still did not surrender. Three days later, Maj. Charles W. Sweeney, commander of the 393rd BMS and piloting "Bockscar" flew over Nagasaki. A few minutes after 9 a.m., bombardier Capt. Kermit K. Beahan toggled the bomb switch. Less than a minute later, Nagasaki became the second city attacked with the devastating weapon. The Japanese surrendered in the following days thereby ending World War II.
The end of World War II prompted the cancellation of over 5,000 B-29s, still on order in September 1945. However, several B 29s well along in production were completed. For all practical purposes, production did not end before June 1946, the last B-29 being delivered on the 10th.
The AAF accepted a grand total of 3,960 B-29s: 3,943 B-29s, 3 XB-29s (including the experimental plane which crashed before delivery), and 14 B-29 prototypes. Actually, B-29s, B-29As, and B-29Bs made up the production total. The B-29 and B-29A were alike and barely differed from the B-29B. The B model was about 2,000 pounds lighter than the A, had an extra 150 feet in service ceiling, and a slightly longer range.
Immediately post-World War II, SAC's bomber inventory housed the B-29 Superfortress, the plane that had dropped atomic bombs over Hiroshima and Nagasaki. In 1946, the Soviets began design of their long-range bomber, the Tu-4, modeled directly on B-29s captured during 1944. The B-29 was SAC's first Cold War aircraft, and even as late as the close of 1948 the Air Force had modified only 60 of the planes to carry the atomic bomb. Its infrastructure, hangars, and ancillaries were reused from World War II facilities. While the B-29 was the long-range aircraft that revolutionized air war, the aircraft could only fly the U.S.-Soviet corridor one way, and could not achieve that distance heavily loaded.
With the advent of the conflict in Korea in June 1950, the B-29 was once again thrust into battle. For the next several years it was effectively used for attacking targets in North Korea. The Warner Robins Air Materiel Area (WRAMA) literally unwrapped and refurbished hundreds of "Cocooned" Boeing B-29 Superfortresses. Understaffed and working around the clock, they made sure that United Nations forces in the Far East had the necessary tools to fight the North Korean invaders. This was particularly true with the key role B-29s played in bombing Communist supply lines and staving off the enemy's assault on Allied forces pinned down inside the Pusan Perimeter. B-29s detached from Twentieth Air Force continued flying combat missions until the end of the war in 1953. By 1955, with the situation in Korea stabilized and intercontinental-range bombers entering service, the need no longer existed for a B-29 numbered air force in the Pacific.
The B-29 MR [MR standing for Modified Receiver] could refuel in mid-air. The KB-29M was the tanker, using what was called the British 'looped hose' method, a 400 foot length of hose that tethered the two airplanes together. In order to extend the range of the new generation of jet aircraft, a B-29 was also fitted with a flying boom for experiments in air-to-air refueling.
A stop-gap measure to fill the long-range bomber requirement in the Cold War, the Boeing B-29D Washington began entering service with UK Bomber Command Squadrons during August 1950. The type began to be retired in 1953 with the advent of the V-bombers, but the last did not leave the RAF until 1958.
- KB-29M: In 1948, 92 B-29s were sent to the newly reopened Boeing Wichita Plant for conversion to hose type tankers, subsequently known as KB-29Ms. This project was urgent, being directly associated with the build up of the atomic forces. The bomber's serious range limitations had called for special arrangements. There was an extensive forward base network, encompassing airfields in Alaska, Canada, England, West Germany, Spain, North Africa, Okinawa, and Guam. But the use of overseas staging bases was a troublesome expedient. A better solution was to develop inflight refueling systems that would give to the SAC bombers the intercontinental striking range they still lacked.
The first such system was featured by the K 29M, which was fitted with British developed hose refueling equipment. The British system involved trailing a hose from the tanker to the receiver and transferring fuel practically by means of gravity. The receiver aircraft (listed as B-29MR, in the B-29's case) also required modifications, but they were relatively minor. In contrast, the tanker modifications were extensive. Each bomb bay was fitted with a separate jettisonable tank holding approximately 2,300 gallons of fuel. These tanks were connected to the aircraft's normal fuel system so that fuel from it could also be transferred to the receiver bomber. The KB-29M's inflight refueling system required that the tanker and receiver fly in formation, with the tanker above and ahead trailing a cable referred to as the hauling line. The receiver trailed a line of its own from its refueling receptacle. Called the contact line, this line was so equipped that it could hook the tanker's trailing line and lock the two lines together. The receiver operator then caught the lines, separated them, secured them, pulled the tanker's refueling hose and put it into the receptacle of his bomber. The whole procedure, obviously, was perilous from the start, and the KB-29Ms, after reaching the inventory in late 1948, were replaced within a few years.
- KB-29P: The hose refueling system had many disadvantages, especially in the lengthy time required to make contact, the slow rate of fuel transfer, and the very limited airspeed imposed by the hoses. Boeing therefore soon developed on its own an aerodynamically controlled swiveling and telescoping arm, known as the "Flying Boom." Essentially, this system consisted of a telescopic pipe, which was lowered from the tanker, and connected to a socket in the receiver aircraft. The system was entirely controlled by an operator in the tanker, and the fuel transfer was made with the aid of a pump. B-29s so equipped were designated KB-29Ps. The first of 116 KB-29Ps reached SAC's 97th Air Refueling Squadron on 1 September 1950, the total contingent being delivered by the end of 1951. In spite of the increasing availability of the much faster KC 97, 25 SAC retained many of its KB-29Ps until 1957. The Tactical Air Command gave up its last KB-29s in the middle of that year.
- RB-29: Nearly 120 B-29s were converted to the reconnaissance configuration and redesignated as RB-29s. Some of these aircraft, known as F 13s during World War II, were first fitted with fairly primitive photographic equipment: 3 K 1713s, 2 K 22s, and 1 K 18 camera. After 1948, when the RB-29 designation came into being, the converted bombers began acquiring more sophisticated components. The RB-29s were assigned to the 91st Strategic Reconnaissance Squadron, which like other SAC units played a crucial role during the Korean conflict. The RB-29s followed the phaseout pattern of the bombers from which they derived. The same reasons prompted their retirement.
- TB-29: Some B-29s, fitted with additional trainee or instructor stations, recording equipment, and related types of apparatus, were used for training and identified as TB-29s.
- VB-29: A few B-29s, after being internally refurbished, were used for the transportation of key personnel.
- WB-29: Some B-29s were modified to carry meteorological equipment and used on weather reconnaissance flights. Designated as WB-29s in 1948, these aircraft were the last B-29s to phase out of the regular Air Force.
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