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152-688: The Boeing B-29 Superfortress is 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 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

304-514: A bill of materials . This type of specification is a collaborative effort between a specification writer and a quantity surveyor . This approach is unusual in North America, where each bidder performs a quantity survey on the basis of both drawings and specifications. In many countries on the European continent, content that might be described as "specifications" in the United States are covered under

456-412: A functional specification (also, functional spec or specs or functional specifications document (FSD) ) is the set of documentation that describes the behavior of a computer program or larger software system . The documentation typically describes various inputs that can be provided to the software system and how the system responds to those inputs. Web services specifications are often under

608-577: A standard which is often referenced by a contract or procurement document, or an otherwise agreed upon set of requirements (though still often used in the singular). In any case, it provides the necessary details about the specific requirements. Standards for specifications may be provided by government agencies, standards organizations ( SAE , AWS , NIST , ASTM , ISO / IEC , CEN / CENELEC , DoD , etc.), trade associations , corporations , and others. A memorandum published by William J. Perry , U.S. Defense Secretary , on 29 June 1994 announced that

760-608: 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. There were two Boeing operated plants at Renton, Washington ( Boeing Renton Factory ), and one in Wichita, Kansas (now Spirit AeroSystems ), a Bell plant at Marietta, Georgia , near Atlanta ("Bell-Atlanta"), and a Martin plant at Bellevue, Nebraska ("Martin-Omaha" – Offutt Field ). Thousands of subcontractors were also involved in

912-674: A "Structured Product Label" which drug manufacturers must by mandate use to submit electronically the information on a drug label. Recently, the ISO has made some progress in the area of food and drug standards and formal specifications for data about regulated substances through the publication of ISO 11238. In many contexts, particularly software, specifications are needed to avoid errors due to lack of compatibility, for instance, in interoperability issues. For instance, when two applications share Unicode data, but use different normal forms or use them incorrectly, in an incompatible way or without sharing

1064-565: A B-29, damaging it, but was shot down by return fire. One B-29 was lost, possibly the one damaged by Flt Lt Therdsak. On 14 April 1945, a second B-29 raid on Bangkok destroyed two key power plants and was the last major attack conducted against Thai targets. The B-29 effort was gradually shifted to the new bases in the Mariana Islands in the Central Pacific , with the last B-29 combat mission from India flown on 29 March 1945. In addition to

1216-460: A bent aluminium sheet for blades, thus creating an airfoil shape. They were heavily undercambered , and this plus the absence of lengthwise twist made them less efficient than the Wright propellers. Even so, this was perhaps the first use of aluminium in the construction of an airscrew. Originally, a rotating airfoil behind the aircraft, which pushes it, was called a propeller, while one which pulled from

1368-468: A childhood fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu, but powered by rubber bands. By the end of the century, he had progressed to using sheets of tin for rotor blades and springs for power. His writings on his experiments and models would become influential on future aviation pioneers. William Bland sent designs for his "Atmotic Airship" to

1520-470: 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. The crew would enjoy, for

1672-457: A craft that weighed 3.5 long tons (3.6 t), with a 110 ft (34 m) wingspan that was powered by two 360 hp (270 kW) steam engines driving two propellers. In 1894, his machine was tested with overhead rails to prevent it from rising. The test showed that it had enough lift to take off. One of Pénaud's toys, given as a gift by their father , inspired the Wright brothers to pursue

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1824-416: A fixed-pitch prop once airborne. The spring-loaded "two-speed" VP prop is set to fine for takeoff, and then triggered to coarse once in cruise, the propeller remaining coarse for the remainder of the flight. After World War I , automatic propellers were developed to maintain an optimum angle of attack. This was done by balancing the centripetal twisting moment on the blades and a set of counterweights against

1976-428: A greater flow of cooling air into the intakes, which had baffles installed to direct a stream of air onto the exhaust valves. Oil flow to the valves was also increased, asbestos baffles were installed around rubber push rod fittings to prevent oil loss, thorough pre-flight inspections were made to detect unseated valves, and mechanics frequently replaced the uppermost five cylinders (every 25 hours of engine time) and

2128-559: A gross takeoff weight of 155,000 pounds (70,000 kg). Almost a year later, in October 1946, the same B-29 flew 9,422 miles (15,163 km) nonstop from Oahu, Hawaii, to Cairo, Egypt, in less than 40 hours, demonstrating the possibility of routing airlines over the polar ice cap. Although considered for other theaters, and briefly evaluated in the UK, the B-29 was exclusively used in World War II in

2280-467: A large number of blades. A fan therefore produces a lot of thrust for a given diameter but the closeness of the blades means that each strongly affects the flow around the others. If the flow is supersonic, this interference can be beneficial if the flow can be compressed through a series of shock waves rather than one. By placing the fan within a shaped duct , specific flow patterns can be created depending on flight speed and engine performance. As air enters

2432-528: A low- drag wing and as such are poor in operation when at other than their optimum angle of attack . Therefore, most propellers use a variable pitch mechanism to alter the blades' pitch angle as engine speed and aircraft velocity are changed. A further consideration is the number and the shape of the blades used. Increasing the aspect ratio of the blades reduces drag but the amount of thrust produced depends on blade area, so using high-aspect blades can result in an excessive propeller diameter. A further balance

2584-402: A major investment has been made in actually implementing the design. An alternative approach is to use provably correct refinement steps to transform a specification into a design, and ultimately into an actual implementation, that is correct by construction. In (hardware, software, or enterprise) systems development, an architectural specification is the set of documentation that describes

2736-469: A manufacturer to help people choose or use the products. A data sheet is not a technical specification in the sense of informing how to produce. An " in-service " or " maintained as " specification , specifies the conditions of a system or object after years of operation, including the effects of wear and maintenance (configuration changes). Specifications are a type of technical standard that may be developed by any of various kinds of organizations, in both

2888-639: A minimum set of interoperability specification, errors and data loss can result. For example, Mac OS X has many components that prefer or require only decomposed characters (thus decomposed-only Unicode encoded with UTF-8 is also known as "UTF8-MAC"). In one specific instance, the combination of OS X errors handling composed characters, and the samba file- and printer-sharing software (which replaces decomposed letters with composed ones when copying file names), has led to confusing and data-destroying interoperability problems. Applications may avoid such errors by preserving input code points, and normalizing them to only

3040-488: A move to "greater use of performance and commercial specifications and standards" was to be introduced, which Perry saw as "one of the most important actions that [the Department of Defense] should take" at that time. The following British standards apply to specifications: A design/product specification does not necessarily prove a product to be correct or useful in every context. An item might be verified to comply with

3192-646: A night raid on Omura in Kyushu, Japan, the General H. H. Arnold Special (42-6365) was damaged and forced to divert to Vladivostok in the Soviet Union. The crew was interned. On 21 November 1944, Ding Hao (42-6358) was damaged during a raid on an aircraft factory at Omura and was also forced to divert to Vladivostok. The interned crews of these four B-29s were allowed to escape into American-occupied Iran in January 1945, but none of

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3344-415: A propeller efficiency of about 73.5% at cruise for a Cessna 172 . This is derived from his "Bootstrap approach" for analyzing the performance of light general aviation aircraft using fixed pitch or constant speed propellers. The efficiency of the propeller is influenced by the angle of attack (α). This is defined as α = Φ - θ, where θ is the helix angle (the angle between the resultant relative velocity and

3496-453: A propeller suffers when transonic flow first appears on the tips of the blades. As the relative air speed at any section of a propeller is a vector sum of the aircraft speed and the tangential speed due to rotation, the flow over the blade tip will reach transonic speed well before the aircraft does. When the airflow over the tip of the blade reaches its critical speed , drag and torque resistance increase rapidly and shock waves form creating

3648-405: A set of documented requirements to be satisfied by a material, design, product, or service. A specification is often a type of technical standard . There are different types of technical or engineering specifications (specs), and the term is used differently in different technical contexts. They often refer to particular documents, and/or particular information within them. The word specification

3800-450: A sharp increase in noise. Aircraft with conventional propellers, therefore, do not usually fly faster than Mach 0.6. There have been propeller aircraft which attained up to the Mach 0.8 range, but the low propeller efficiency at this speed makes such applications rare. The tip of a propeller blade travels faster than the hub. Therefore, it is necessary for the blade to be twisted so as to decrease

3952-551: A specific list of products, or "open" allowing for substitutions made by the constructor. Most construction specifications are a combination of performance-based and proprietary types, naming acceptable manufacturers and products while also specifying certain standards and design criteria that must be met. While North American specifications are usually restricted to broad descriptions of the work, European ones and Civil work can include actual work quantities, including such things as area of drywall to be built in square meters, like

4104-494: A specific material type (concrete) or a work product (steel door) of the construction work. A specific material may be covered in several locations, depending on the work result: stainless steel (for example) can be covered as a sheet material used in flashing and sheet Metal in division 07; it can be part of a finished product, such as a handrail, covered in division 05; or it can be a component of building hardware, covered in division 08. The original listing of specification divisions

4256-402: A specification or stamped with a specification number: this does not, by itself, indicate that the item is fit for other, non-validated uses. The people who use the item ( engineers , trade unions , etc.) or specify the item ( building codes , government, industry, etc.) have the responsibility to consider the choice of available specifications, specify the correct one, enforce compliance, and use

4408-417: A spring and the aerodynamic forces on the blade. Automatic props had the advantage of being simple, lightweight, and requiring no external control, but a particular propeller's performance was difficult to match with that of the aircraft's power plant. The most common variable pitch propeller is the constant-speed propeller . This is controlled by a hydraulic constant speed unit (CSU). It automatically adjusts

4560-508: A wound-up spring device and demonstrated it to the Russian Academy of Sciences . It was powered by a spring, and was suggested as a method to lift meteorological instruments. In 1783, Christian de Launoy , and his mechanic , Bienvenu, used a coaxial version of the Chinese top in a model consisting of contrarotating turkey flight feathers as rotor blades, and in 1784, demonstrated it to

4712-460: Is a mathematical description of software or hardware that may be used to develop an implementation . It describes what the system should do, not (necessarily) how the system should do it. Given such a specification, it is possible to use formal verification techniques to demonstrate that a candidate system design is correct with respect to that specification. This has the advantage that incorrect candidate system designs can be revised before

Boeing B-29 Superfortress - Misplaced Pages Continue

4864-553: Is a process for dealing with observations that are out-of-specification. The United States Food and Drug Administration has published a non-binding recommendation that addresses just this point. At the present time, much of the information and regulations concerning food and food products remain in a form which makes it difficult to apply automated information processing, storage and transmission methods and techniques. Data systems that can process, store and transfer information about food and food products need formal specifications for

5016-506: Is broadly defined as "to state explicitly or in detail" or "to be specific". A requirement specification is a documented requirement , or set of documented requirements, to be satisfied by a given material, design, product, service, etc. It is a common early part of engineering design and product development processes in many fields. A functional specification is a kind of requirement specification, and may show functional block diagrams. A design or product specification describes

5168-415: Is common for one organization to refer to ( reference , call out , cite ) the standards of another. Voluntary standards may become mandatory if adopted by a government or business contract. In engineering , manufacturing , and business , it is vital for suppliers , purchasers , and users of materials, products, or services to understand and agree upon all requirements. A specification may refer to

5320-560: Is currently less fruitful and not yet put forward as an urgent agenda due to the tight restrictions of regional or national constitution. Specifications and other standards can be externally imposed as discussed above, but also internal manufacturing and quality specifications. These exist not only for the food or pharmaceutical product but also for the processing machinery , quality processes, packaging , logistics ( cold chain ), etc. and are exemplified by ISO 14134 and ISO 15609. The converse of explicit statement of specifications

5472-451: Is hydraulic, with engine oil serving as the hydraulic fluid. However, electrically controlled propellers were developed during World War II and saw extensive use on military aircraft, and have recently seen a revival in use on home-built aircraft. Another design is the V-Prop , which is self-powering and self-governing. On most variable-pitch propellers, the blades can be rotated parallel to

5624-414: Is not covered by the above standards , it can be evaluated by the additional source of pharmacopoeias from other nations, from industrial specifications, or from a standardized formulary such as A similar approach is adopted by the food manufacturing, of which Codex Alimentarius ranks the highest standards, followed by regional and national standards. The coverage of food and drug standards by ISO

5776-528: Is owned by the Royal Institute of British Architects (RIBA) through their commercial group RIBA Enterprises (RIBAe). NBS master specifications provide content that is broad and comprehensive, and delivered using software functionality that enables specifiers to customize the content to suit the needs of the project and to keep up to date. UK project specification types fall into two main categories prescriptive and performance. Prescriptive specifications define

5928-472: Is suitable for airliners, but the noise generated is tremendous (see the Antonov An-70 and Tupolev Tu-95 for examples of such a design). Forces acting on the blades of an aircraft propeller include the following. Some of these forces can be arranged to counteract each other, reducing the overall mechanical stresses imposed. The purpose of varying pitch angle is to maintain an optimal angle of attack for

6080-409: Is that using a smaller number of blades reduces interference effects between the blades, but to have sufficient blade area to transmit the available power within a set diameter means a compromise is needed. Increasing the number of blades also decreases the amount of work each blade is required to perform, limiting the local Mach number – a significant performance limit on propellers. The performance of

6232-489: Is used to help slow the aircraft after landing and is particularly advantageous when landing on a wet runway as wheel braking suffers reduced effectiveness. In some cases reverse pitch allows the aircraft to taxi in reverse – this is particularly useful for getting floatplanes out of confined docks. Counter-rotating propellers are sometimes used on twin-engine and multi-engine aircraft with wing-mounted engines. These propellers turn in opposite directions from their counterpart on

Boeing B-29 Superfortress - Misplaced Pages Continue

6384-583: The B-32 ), Lockheed (the Lockheed XB-30 ), and Douglas (the Douglas XB-31 ). 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 24 August 1940, with the order being revised to add a third flying aircraft on 14 December. Consolidated continued to work on its Model 33, as it

6536-538: The French Academy of Sciences . A dirigible airship was described by Jean Baptiste Marie Meusnier presented in 1783. The drawings depict a 260-foot-long (79 m) streamlined envelope with internal ballonets that could be used for regulating lift. The airship was designed to be driven by three propellers. In 1784 Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, the first recorded means of propulsion carried aloft. Sir George Cayley , influenced by

6688-505: The Pacific Theatre . The use of YB-29-BW 41-36393 , the so-named Hobo Queen , one of the service test aircraft flown around several British airfields in early 1944, was part of a "disinformation" program from its mention in an American-published Sternenbanner German-language propaganda leaflet from Leap Year Day in 1944, meant to be circulated within the Reich, with the intent to deceive

6840-658: The Royal Australian Air Force (RAAF) in 1952. They were attached to the Aircraft Research and Development Unit and used in trials conducted on behalf of the British Ministry of Supply . Both aircraft were placed in storage in 1956 and were sold for scrap in 1957. At the end of WWII, Soviet development of modern four-engine heavy bombers lagged behind the West. The Petlyakov Pe-8 —the sole heavy bomber operated by

6992-553: The Silverplate and successor-name "Saddletree" specifications built for the Manhattan Project with Curtiss Electric reversible pitch propellers. The other differences came through added equipment for varied mission roles. These roles included cargo carriers (CB); rescue aircraft (SB); weather ships (WB); and trainers (TB); and aerial tankers (KB). Some were used for odd purposes such as flying relay television transmitters under

7144-526: The Silverplate series, being extensively modified to carry nuclear weapons. Early consideration was given to using the British Lancaster as a nuclear bomber, as this would require less modification. However, the superior range and high-altitude performance of the B-29 made it a much better choice, and after the B-29 began to be modified in November 1943 for carrying the atomic bomb, the suggestion for using

7296-642: The Soviet Air Forces —first flew in 1936. Intended to replace the obsolete Tupolev TB-3 , only 93 Pe-8s were built by the end of WWII. During 1944 and 1945, four B-29s made emergency landings in Soviet territory after bombing raids on Japanese Manchuria and Japan. In accordance with Soviet neutrality in the Pacific War , the bombers were interned by the Soviets despite American requests for their return. Rather than return

7448-458: The Tupolev Tu-95 propel it at a speed exceeding the maximum once considered possible for a propeller-driven aircraft using an exceptionally coarse pitch. Early pitch control settings were pilot operated, either with a small number of preset positions or continuously variable. The simplest mechanism is the ground-adjustable propeller , which may be adjusted on the ground, but is effectively

7600-488: The Tupolev Tu-95 , which can reach 575 mph (925 km/h). The earliest references for vertical flight came from China. Since around 400 BC, Chinese children have played with bamboo flying toys . This bamboo-copter is spun by rolling a stick attached to a rotor between one's hands. The spinning creates lift, and the toy flies when released. The 4th-century AD Daoist book Baopuzi by Ge Hong (抱朴子 "Master who Embraces Simplicity") reportedly describes some of

7752-715: The Yalu River , and for attacks on dams. The aircraft also was used for numerous leaflet drops in North Korea, such as those for Operation Moolah . A Superfortress of the 91st Strategic Reconnaissance Squadron flew the last B-29 mission of the war on 27 July 1953. Over the course of the war, B-29s flew 20,000 sorties and dropped 200,000 tonnes (220,000 tons) of bombs. B-29 gunners were credited with shooting down 27 enemy aircraft. In turn 78 B-29s were lost; 57 B-29 and reconnaissance variants were lost in action and 21 were non-combat losses. Soviet records show that one MiG-15 jet fighter

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7904-544: 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 (equivalent to $ 51 billion in 2022), far exceeding

8056-513: The federal government and its agencies stipulates that a copy of the drawings and specifications must be kept available on a construction site. Specifications in Egypt form part of contract documents. The Housing and Building National Research Center ( HBRC ) is responsible for developing construction specifications and codes. The HBRC has published more than 15 books which cover building activities like earthworks , plastering, etc. Specifications in

8208-477: The public and private sectors. Example organization types include a corporation , a consortium (a small group of corporations), a trade association (an industry-wide group of corporations), a national government (including its different public entities, regulatory agencies , and national laboratories and institutes), a professional association (society), a purpose-made standards organization such as ISO , or vendor-neutral developed generic requirements. It

8360-720: The structure , behavior , and more views of that system . A program specification is the definition of what a computer program is expected to do. It can be informal , in which case it can be considered as a user manual from a developer point of view, or formal , in which case it has a definite meaning defined in mathematical or programmatic terms. In practice, many successful specifications are written to understand and fine-tune applications that were already well-developed, although safety-critical software systems are often carefully specified prior to application development. Specifications are most important for external interfaces that must remain stable. In software development ,

8512-526: The "Silverplate" modified aircraft of the 509th Composite Group remained the only aircraft capable of delivering the atomic bomb, and so the unit was involved in the Operation Crossroads series of tests, with B-29 Dave's Dream dropping a "Fat Man"-type bomb in Test Able on 1 July 1946. Some B-29s, fitted with filtered air sampling scoops, were used to monitor above-ground nuclear weapons testing by

8664-470: The $ 1.9 billion cost of the Manhattan Project , 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. A few were also used as flying television transmitters by the Stratovision company. The Royal Air Force flew the B-29 with the service name Washington from 1950 to 1954 when

8816-416: The 50 division format, which was adopted in both the United States and Canada starting in 2004. The 16 division format is no longer considered standard, and is not supported by either CSI or CSC, or any of the subscription master specification services, data repositories, product lead systems, and the bulk of governmental agencies. The United States' Federal Acquisition Regulation governing procurement for

8968-594: The Air Corps issued a formal specification for a so-called "superbomber" that could deliver 20,000 lb (9,100 kg) of bombs to a target 2,667 mi (4,292 km) away, and at a speed of 400 mph (640 km/h). 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 11 May 1940, in competition with designs from Consolidated Aircraft (the Model 33, which later became

9120-720: The B-29 deployed initially against Germany, transferring to the Pacific only after the end of the war in Europe. 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 at the direction of President Franklin D. Roosevelt as a promise to China, called Operation Matterhorn , deployed the B-29 units to attack Japan from four forward bases in southern China , with five main bases in India , and to attack other targets in

9272-421: 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

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9424-472: The B-29 in many later bombers and transports. Production of the B-29 was phased out after WWII, with the last example completed by Boeing's Renton factory on 28 May 1946. Many aircraft went into storage, being declared excess inventory, and were ultimately scrapped as surplus. Others remained in the active inventory and equipped the Strategic Air Command when it formed on 21 March 1946. In particular,

9576-754: The B-29. Twenty B-29s remain as static displays, but only two, FIFI and Doc , still fly. Before World War II , the United States Army Air Corps 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

9728-472: 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

9880-580: The B-29s were returned after Stalin ordered the Tupolev OKB to examine and copy the B-29 and produce a design ready for quantity production as soon as possible. Because aluminum in the USSR was supplied in different gauges from that available in the US (metric vs imperial), the entire aircraft had to be extensively re-engineered. In addition, Tupolev substituted his own favored airfoil sections for those used by Boeing, with

10032-657: The Construction Specifications Institute and the Registered Specification Writer (RSW) through Construction Specifications Canada. Specification writers may be separate entities such as sub-contractors or they may be employees of architects, engineers, or construction management companies. Specification writers frequently meet with manufacturers of building materials who seek to have their products specified on upcoming construction projects so that contractors can include their products in

10184-616: The Germans into believing that the B-29 would be deployed to Europe. American post-war military assistance programs loaned the RAF 87 Superfortresses, to equip eight RAF Bomber Command squadrons. The aircraft was known as the Washington B.1 in RAF service and served from March 1950 until the last bombers were returned in March 1954. Deployment was restricted to long-range training for strategic attacks against

10336-523: The Great Exhibition held in London in 1851, where a model was displayed. This was an elongated balloon with a steam engine driving twin propellers suspended underneath. Alphonse Pénaud developed coaxial rotor model helicopter toys in 1870, also powered by rubber bands. In 1872 Dupuy de Lome launched a large navigable balloon, which was driven by a large propeller turned by eight men. Hiram Maxim built

10488-563: The Himalayas (12 KIA, 11 crew and one passenger). This raid, which did little damage to the target, with only one bomb striking the target factory complex, nearly exhausted fuel stocks at the Chengdu B-29 bases, resulting in a slow-down of operations until the fuel stockpiles could be replenished. Starting in July, the raids against Japan from Chinese airfields continued at relatively low intensity. Japan

10640-636: The Himalayas, or " The Hump ") took place on 24 April 1944. The first B-29 combat mission was flown on 5 June 1944, with 77 out of 98 B-29s launched from India bombing the railroad shops in Bangkok and elsewhere in Thailand . Five B-29s were lost during the mission, none to hostile fire. On 5 June 1944, B-29s raided Bangkok , in what is reported as a test before being deployed against the Japanese home islands . Sources do not report from where they launched and vary as to

10792-592: The Japanese Showa steel mill in Anshan , Manchuria . On 20 August 1944, Cait Paomat (42-93829), flying from Chengdu, was damaged by anti-aircraft gunfire during a raid on the Yawata Iron Works. Due to the damage it sustained, the crew elected to divert to the Soviet Union. The aircraft crashed in the foothills of Sikhote-Alin mountain range east of Khabarovsk after the crew bailed out. On 11 November 1944, during

10944-680: The Japanese capital since the Doolittle Raid in April 1942, 73rd Bomb Wing wing commander Brigadier General Emmett O'Donnell Jr. acted as mission command pilot in B-29 Dauntless Dotty . The campaign of incendiary raids started with the bombardment of Kobe on 4 February 1945, then peaked early with the most destructive bombing raid in history (even when the later Silverplate -flown nuclear attacks on Hiroshima and Nagasaki are considered) on

11096-600: The Lancaster never came up again. The most significant modification was the enlargement of the bomb bay enabling each aircraft to carry either the Thinman or Fatman weapons. These Silverplate bombers differed from other B-29s then in service by having fuel injection and reversible props . Also, to make a lighter aircraft, the Silverplate B-29s were stripped of all guns, except for those on the tail. Pilot Charles Sweeney credits

11248-578: The Marianas. US forces invaded Saipan on 15 June 1944. Despite a Japanese naval counterattack which led to the Battle of the Philippine Sea and heavy fighting on land, Saipan 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

11400-481: 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 Lindbergh convinced General Henry H. Arnold to produce a new bomber in large numbers to counter the Germans' bomber production. In December 1939,

11552-485: The Soviet Union, which was beyond the range of the RAF's Avro Lincolns . The phase-out was occasioned by deliveries of the English Electric Canberra bombers. Three Washingtons modified for ELINT duties and a standard bomber version used for support by No. 192 Squadron RAF were decommissioned in 1958, being replaced by de Havilland Comet aircraft. Two British Washington B.1 aircraft were transferred to

11704-569: The Soviets themselves already having their own Wright R-1820 -derived 18 cylinder radial engine, the Shvetsov ASh-73 of comparable power and displacement to the B-29's Duplex Cyclone radials available to power their design. In 1947, the Soviets debuted both the Tupolev Tu-4 ( NATO ASCC code named Bull), and the Tupolev Tu-70 transport variant. The Soviets used tail-gunner positions similar to

11856-543: The UK are part of the contract documents that accompany and govern the construction of a building. They are prepared by construction professionals such as architects , architectural technologists , structural engineers , landscape architects and building services engineers . They are created from previous project specifications, in-house documents or master specifications such as the National Building Specification (NBS). The National Building Specification

12008-539: The US and the USSR by sampling airborne radioactive contamination . The USAF also used the aircraft for long-range weather reconnaissance (WB-29), for signals intelligence gathering (EB-29) and photographic reconnaissance (RB-29). The B-29 was used in 1950–53 in the Korean War . At first, the bomber was used in normal strategic day-bombing missions, although North Korea's few strategic targets and industries were quickly destroyed. More importantly, in 1950 numbers of Soviet MiG-15 jet fighters appeared over Korea, and after

12160-523: The United States and are usually subscription based. Specifications can be either "performance-based", whereby the specifier restricts the text to stating the performance that must be achieved by the completed work, "prescriptive" where the specifier states the specific criteria such as fabrication standards applicable to the item, or "proprietary", whereby the specifier indicates specific products, vendors and even contractors that are acceptable for each workscope. In addition, specifications can be "closed" with

12312-517: The United States and updated every two years. While there is a tendency to believe that "specifications overrule drawings" in the event of discrepancies between the text document and the drawings, the actual intent must be made explicit in the contract between the Owner and the Contractor. The standard AIA (American Institute of Architects) and EJCDC (Engineering Joint Contract Documents Committee) states that

12464-399: The air in the propeller slipstream. Contra-rotation also increases the ability of a propeller to absorb power from a given engine, without increasing propeller diameter. However the added cost, complexity, weight and noise of the system rarely make it worthwhile and it is only used on high-performance types where ultimate performance is more important than efficiency. A fan is a propeller with

12616-428: The aircraft maintain speed and altitude with the operative engines. Feathering also prevents windmilling , the turning of engine components by the propeller rotation forced by the slipstream; windmilling can damage the engine, start a fire, or cause structural damage to the aircraft. Most feathering systems for reciprocating engines sense a drop in oil pressure and move the blades toward the feather position, and require

12768-585: The aircraft, the Soviets reverse engineered the American B-29s and used them as a pattern for the Tupolev Tu-4 . On 31 July 1944, Ramp Tramp ( serial number 42-6256), of the United States Army Air Forces 462nd (Very Heavy) Bomb Group was diverted to Vladivostok , Russia , after an engine failed and the propeller could not be feathered . This B-29 was part of a 100-aircraft raid against

12920-405: The airflow to stop rotation of the propeller and reduce drag when the engine fails or is deliberately shut down. This is called feathering , a term borrowed from rowing . On single-engined aircraft, whether a powered glider or turbine-powered aircraft, the effect is to increase the gliding distance. On a multi-engine aircraft, feathering the propeller on an inoperative engine reduces drag, and helps

13072-410: The angle of attack of the blade gradually and therefore produce uniform lift from the hub to the tip. The greatest angle of incidence, or the highest pitch, is at the hub while the smallest angle of incidence or smallest pitch is at the tip. A propeller blade designed with the same angle of incidence throughout its entire length would be inefficient because as airspeed increases in flight, the portion near

13224-478: The application's preferred normal form for internal use. Such errors may also be avoided with algorithms normalizing both strings before any binary comparison. However errors due to file name encoding incompatibilities have always existed, due to a lack of minimum set of common specification between software hoped to be inter-operable between various file system drivers, operating systems, network protocols, and thousands of software packages. A formal specification

13376-407: The blade pitch in order to maintain a constant engine speed for any given power control setting. Constant-speed propellers allow the pilot to set a rotational speed according to the need for maximum engine power or maximum efficiency, and a propeller governor acts as a closed-loop controller to vary propeller pitch angle as required to maintain the selected engine speed. In most aircraft this system

13528-440: The blade rotation direction) and Φ is the blade pitch angle. Very small pitch and helix angles give a good performance against resistance but provide little thrust, while larger angles have the opposite effect. The best helix angle is when the blade is acting as a wing producing much more lift than drag. However, 'lift-and-drag' is only one way to express the aerodynamic force on the blades. To explain aircraft and engine performance

13680-403: The blade tips approach the speed of sound. The maximum relative velocity is kept as low as possible by careful control of pitch to allow the blades to have large helix angles. A large number of blades are used to reduce work per blade and so circulation strength. Contra-rotating propellers are used. The propellers designed are more efficient than turbo-fans and their cruising speed (Mach 0.7–0.85)

13832-644: The bomb bay doors. The solution was to have bomb bays that were not pressurized 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 September 1941, the United States Army Air Forces ' 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. Air Force planning throughout 1942 and early 1943 continued to have

13984-524: The building code or municipal code. Civil and infrastructure work in the United States often includes a quantity breakdown of the work to be performed as well. Although specifications are usually issued by the architect 's office, specification writing itself is undertaken by the architect and the various engineers or by specialist specification writers. Specification writing is often a distinct professional trade, with professional certifications such as "Certified Construction Specifier" (CCS) available through

14136-400: 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

14288-545: 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. In early 1945, Major General Curtis 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

14440-651: The drawings and specifications are complementary, together providing the information required for a complete facility. Many public agencies, such as the Naval Facilities Command (NAVFAC) state that the specifications overrule the drawings. This is based on the idea that words are easier for a jury (or mediator) to interpret than drawings in case of a dispute. The standard listing of construction specifications falls into 50 Divisions , or broad categories of work types and work results involved in construction. The divisions are subdivided into sections, each one addressing

14592-460: The dream of flight. The twisted airfoil (aerofoil) shape of an aircraft propeller was pioneered by the Wright brothers. While some earlier engineers had attempted to model air propellers on marine propellers , the Wright Brothers realized that a propeller is essentially the same as a wing , and were able to use data from their earlier wind tunnel experiments on wings, introducing a twist along

14744-468: The duct needs to be shaped in a different manner than one for higher speed flight. More air is taken in and the fan therefore operates at an efficiency equivalent to a larger un-ducted propeller. Noise is also reduced by the ducting and should a blade become detached the duct would help contain the damage. However the duct adds weight, cost, complexity and (to a certain degree) drag. Specification (technical standard) A specification often refers to

14896-575: The duct, its speed is reduced while its pressure and temperature increase. If the aircraft is at a high subsonic speed this creates two advantages: the air enters the fan at a lower Mach speed; and the higher temperature increases the local speed of sound. While there is a loss in efficiency as the fan is drawing on a smaller area of the free stream and so using less air, this is balanced by the ducted fan retaining efficiency at higher speeds where conventional propeller efficiency would be poor. A ducted fan or propeller also has certain benefits at lower speeds but

15048-591: 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. B-29s started to arrive in India in early April 1944. The first B-29 flight to airfields in China (over

15200-420: 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

15352-552: The entire engines (every 75 hours). Pilots, including the present-day pilots of the Commemorative Air Force 's Fifi , one of the last two remaining flying B-29s, describe flight after takeoff as being an urgent struggle for airspeed (generally, flight after takeoff should consist of striving for altitude). Radial engines need airflow to keep them cool, and failure to get up to speed as soon as possible could result in an engine failure and risk of fire. One useful technique

15504-463: The estimates leading to their proposals. In February 2015, ArCHspec went live, from ArCH (Architects Creating Homes), a nationwide American professional society of architects whose purpose is to improve residential architecture. ArCHspec was created specifically for use by licensed architects while designing SFR (Single Family Residential) architectural projects. Unlike the more commercial CSI/CSC (50+ division commercial specifications), ArCHspec utilizes

15656-410: The farthest nonstop distance (6,400 miles or 10,300 kilometers) to that date flown by U.S. Army Air Forces aircraft and the first-ever nonstop flight from Japan to Chicago . Two months later, Colonel Clarence S. Irvine commanded another modified B-29, Pacusan Dreamboat , in a world-record-breaking long-distance flight from Guam to Washington, D.C., traveling 7,916 miles (12,740 km) in 35 hours, with

15808-431: The feathering process or the feathering process may be automatic. Accidental feathering is dangerous and can result in an aerodynamic stall ; as seen for example with Yeti Airlines Flight 691 which crashed during approach due to accidental feathering. The propellers on some aircraft can operate with a negative blade pitch angle, and thus reverse the thrust from the propeller. This is known as Beta Pitch. Reverse thrust

15960-474: The features of the solutions for the Requirement Specification, referring to either a designed solution or final produced solution. It is often used to guide fabrication/production. Sometimes the term specification is here used in connection with a data sheet (or spec sheet ), which may be confusing. A data sheet describes the technical characteristics of an item or product, often published by

16112-418: 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 AiResearch . Both the forward and rear crew compartments were to be pressurized, but the designers had to decide whether to have bomb bays that were not pressurized or a fully pressurized fuselage that would have to be de-pressurized prior to opening

16264-533: The flight was terminated due to a serious engine fire. On 18 February 1943, the second prototype, flying out of Boeing Field in Seattle, experienced an engine fire and crashed. The crash killed Boeing test pilot Edmund T. Allen and his 10-man crew, 20 workers at the Frye Meat Packing Plant and a Seattle firefighter. Changes to the production craft came so often and so fast that, in early 1944, B-29s flew from

16416-463: The front was a tractor . Later the term 'pusher' became adopted for the rear-mounted device in contrast to the tractor configuration and both became referred to as 'propellers' or 'airscrews'. The understanding of low speed propeller aerodynamics was fairly complete by the 1920s, but later requirements to handle more power in a smaller diameter have made the problem more complex. Propeller research for National Advisory Committee for Aeronautics (NACA)

16568-557: The fuselage – clockwise on the left engine and counterclockwise on the right – however, there are exceptions (especially during World War II ) such as the P-38 Lightning which turned "outwards" (counterclockwise on the left engine and clockwise on the right) away from the fuselage from the WW II years, and the Airbus A400 whose inboard and outboard engines turn in opposite directions even on

16720-414: The hub would have a negative AOA while the blade tip would be stalled. There have been efforts to develop propellers and propfans for aircraft at high subsonic speeds. The 'fix' is similar to that of transonic wing design. Thin blade sections are used and the blades are swept back in a scimitar shape ( scimitar propeller ) in a manner similar to wing sweepback, so as to delay the onset of shockwaves as

16872-513: The ideas inherent to rotary wing aircraft. Designs similar to the Chinese helicopter toy appeared in Renaissance paintings and other works. It was not until the early 1480s, when Leonardo da Vinci created a design for a machine that could be described as an "aerial screw" , that any recorded advancement was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop

17024-467: The item correctly. Validation of suitability is necessary. Public sector procurement rules in the European Union and United Kingdom require non-discriminatory technical specifications to be used to identify the purchasing organisation's requirements. The rules relating to public works contracts initially prohibited "technical specifications having a discriminatory effect" from 1971; this principle

17176-406: The jet-powered Canberra entered service. The B-29 was the progenitor of a series of Boeing-built bombers, transports, tankers, reconnaissance aircraft, and trainers. For example, the re-engined B-50 Superfortress Lucky Lady II became the first aircraft to fly around the world non-stop, during a 94-hour flight in 1949. The Boeing C-97 Stratofreighter airlifter, which was first flown in 1944,

17328-470: The launch sites for the large B-29 raids against Japan in the final year of the war. The first B-29 arrived on Saipan on 12 October 1944, and the first combat mission was launched from there on 28 October 1944, with 14 B-29s attacking the Truk atoll. The 73rd Bomb Wing launched the first mission against Japan from bases in the Marianas, on 24 November 1944, sending 111 B-29s to attack Tokyo . For this first attack on

17480-400: The length of the blades. This was necessary to maintain a more uniform angle of attack of the blade along its length. Their original propeller blades had an efficiency of about 82%, compared to 90% for a modern (2010) small general aviation propeller, the 3-blade McCauley used on a Beechcraft Bonanza aircraft. Roper quotes 90% for a propeller for a human-powered aircraft. Mahogany was

17632-453: The logistical problems associated with operations from China, the B-29 could reach only a limited part of Japan while flying from Chinese bases. The solution to this problem was to capture the Mariana Islands , which would bring targets such as Tokyo , about 1,500 mi (2,400 km) north of the Marianas within range of B-29 attacks. The Joint Chiefs of Staff agreed in December 1943 to seize

17784-460: The loss of 28 aircraft, future B-29 raids were restricted to night missions, largely in a supply-interdiction role. The B-29 dropped the 1,000 lb (450 kg) VB-3 "Razon" (a range-controllable version of the earlier Azon guided ordnance device) and the 12,000 lb (5,400 kg) VB-13 " Tarzon " MCLOS radio-controlled bombs in Korea, mostly for demolishing major bridges, like the ones across

17936-458: The more concise 16 traditional Divisions, plus a Division 0 (Scope & Bid Forms) and Division 17 (low voltage). Many architects, up to this point, did not provide specifications for residential designs, which is one of the reasons ArCHspec was created: to fill a void in the industry with more compact specifications for residential projects. Shorter form specifications documents suitable for residential use are also available through Arcom, and follow

18088-566: The name of Stratovision . Propeller (aeronautics) The propeller attaches to the power source's driveshaft either directly or through reduction gearing . Propellers can be made from wood, metal or composite materials . Propellers are most suitable for use at subsonic airspeeds generally below about 480 mph (770 km/h), although supersonic speeds were achieved in the McDonnell XF-88B experimental propeller-equipped aircraft. Supersonic tip-speeds are used in some aircraft like

18240-561: The night of 9–10 March 1945 on Tokyo. From then on, the raids intensified, being launched regularly until the end of the war. The attacks succeeded in devastating most large Japanese cities (with the exception of Kyoto and four that were reserved for nuclear attacks), and gravely damaged Japan's war industries. Although less publicly appreciated, the mining of Japanese ports and shipping routes ( Operation Starvation ) carried out by B-29s from April 1945 reduced Japan's ability to support its population and move its troops. The most famous B-29s were

18392-533: The numbers involved—77, 98, and 114 being claimed. Targets were Bangkok's Memorial Bridge and a major power plant. Bombs fell over two kilometers away, damaged no civilian structures, but destroyed some tram lines, and destroyed both a Japanese military hospital and the Japanese secret police headquarters. On 15 June 1944, 68 B-29s took off from bases around Chengdu, 47 B-29s bombed the Imperial Iron and Steel Works at Yawata , Fukuoka Prefecture , Japan . This

18544-406: The organisation's current corporate objectives or priorities. Sometimes a guide or a standard operating procedure is available to help write and format a good specification. A specification might include: Specifications in North America form part of the contract documents that accompany and govern the drawings for construction of building and infrastructure projects. Specifications describe

18696-432: The other wing to balance out the torque and p-factor effects. They are sometimes referred to as "handed" propellers since there are left hand and right hand versions of each prop. Generally, the propellers on both engines of most conventional twin-engined aircraft spin clockwise (as viewed from the rear of the aircraft). To eliminate the critical engine problem, counter-rotating propellers usually turn "inwards" towards

18848-417: The pilot to pull the propeller control back to disengage the high-pitch stop pins before the engine reaches idle RPM . Turboprop control systems usually use a negative torque sensor in the reduction gearbox, which moves the blades toward feather when the engine is no longer providing power to the propeller. Depending on design, the pilot may have to push a button to override the high-pitch stops and complete

19000-399: 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 10 March and 15 April 1944. The most common cause of maintenance headaches and catastrophic failures

19152-535: The production lines directly to modification depots for extensive rebuilds to incorporate the latest changes. AAF-contracted modification centers and its own air depot system struggled to handle the scope of the requirements. Some facilities lacked hangars capable of housing the giant B-29, requiring outdoor work in freezing weather, further delaying necessary modification. 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

19304-473: The project. The first prototype made its maiden flight from Boeing Field , Seattle , on 21 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 30 December 1942, although

19456-553: The propeller blades, giving maximum efficiency throughout the flight regime. This reduces fuel usage. Only by maximising propeller efficiency at high speeds can the highest possible speed be achieved. Effective angle of attack decreases as airspeed increases, so a coarser pitch is required at high airspeeds. The requirement for pitch variation is shown by the propeller performance during the Schneider Trophy competition in 1931. The Fairey Aviation Company fixed-pitch propeller used

19608-473: The quality and performance of building materials, using code citations and published standards, whereas the drawings or building information model (BIM) illustrates quantity and location of materials. The guiding master document of names and numbers is the latest edition of MasterFormat . This is a consensus document that is jointly sponsored by two professional organizations: Construction Specifications Canada and Construction Specifications Institute based in

19760-414: The rather voluminous commercial style of specifications too lengthy for most residential projects and therefore either produce more abbreviated specifications of their own or use ArCHspec (which was specifically created for residential projects). Master specification systems are available from multiple vendors such as Arcom, Visispec, BSD, and Spectext. These systems were created to standardize language across

19912-485: The region from China and India as needed. The Chengdu region was eventually chosen over the Guilin region to avoid having to raise, equip, and train 50 Chinese divisions to protect the advanced bases from Japanese ground attack. 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

20064-495: The representations of data about food and food products in order to operate effectively and efficiently. Development of formal specifications for food and drug data with the necessary and sufficient clarity and precision for use specifically by digital computing systems have begun to emerge from some government agencies and standards organizations: the United States Food and Drug Administration has published specifications for

20216-476: The requirements using generic or proprietary descriptions of what is required, whereas performance specifications focus on the outcomes rather than the characteristics of the components. Specifications are an integral part of Building Information Modeling and cover the non-geometric requirements. Pharmaceutical products can usually be tested and qualified by various pharmacopoeias . Current existing pharmaceutical standards include: If any pharmaceutical product

20368-560: The reversible props for saving Bockscar after making an emergency landing on Okinawa following the Nagasaki bombing. Enola Gay , flown by Colonel Paul Tibbets , dropped the first bomb, called Little Boy , on Hiroshima on 6 August 1945. Enola Gay is fully restored and on display at the Smithsonian's Steven F. Udvar-Hazy Center , outside Dulles Airport near Washington, D.C. Bockscar , piloted by Major Charles W. Sweeney , dropped

20520-424: The rotor from making the craft rotate. As scientific knowledge increased and became more accepted, man continued to pursue the idea of vertical flight. Many of these later models and machines would more closely resemble the ancient bamboo flying top with spinning wings, rather than Leonardo's screw. In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by

20672-411: The same force is expressed slightly differently in terms of thrust and torque since the required output of the propeller is thrust. Thrust and torque are the basis of the definition for the efficiency of the propeller as shown below. The advance ratio of a propeller is similar to the angle of attack of a wing. A propeller's efficiency is determined by Propellers are similar in aerofoil section to

20824-410: The same wing. A contra-rotating propeller or contra-prop places two counter-rotating propellers on concentric drive shafts so that one sits immediately 'downstream' of the other propeller. This provides the benefits of counter-rotating propellers for a single powerplant. The forward propeller provides the majority of the thrust, while the rear propeller also recovers energy lost in the swirling motion of

20976-824: The second bomb, called Fat Man , on Nagasaki three days later. Bockscar is on display at the National Museum of the United States Air Force . Following the surrender of Japan, called V-J Day , B-29s were used for other purposes. A number supplied POWs with food and other necessities by dropping barrels of rations on Japanese POW camps. In September 1945, a long-distance flight was undertaken for public relations purposes: Generals Barney M. Giles , Curtis LeMay , and Emmett O'Donnell Jr. piloted three specially modified B-29s from Chitose Air Base in Hokkaidō to Chicago Municipal Airport , continuing to Washington, D.C. ,

21128-497: The wingspan dimensions. The wing of the Renton-built B-29A-BN used a different subassembly process and was a foot longer in span. The Georgia-built B-29B-BA weighed less through armament reduction. A planned C series with more reliable R-3350s was not built. Moreover, engine packages changed, including the type of propellers and range of the variable pitch. A notable example was the eventual 65 airframes (up to 1947's end) for

21280-445: The wood preferred for propellers through World War I , but wartime shortages encouraged use of walnut , oak , cherry and ash . Alberto Santos Dumont was another early pioneer, having designed propellers before the Wright Brothers for his airships . He applied the knowledge he gained from experiences with airships to make a propeller with a steel shaft and aluminium blades for his 14 bis biplane in 1906. Some of his designs used

21432-460: Was based on the time sequence of construction, working from exterior to interior, and this logic is still somewhat followed as new materials and systems make their way into the construction process. Each section is subdivided into three distinct parts: "general", "products" and "execution". The MasterFormat and SectionFormat systems can be successfully applied to residential, commercial, civil, and industrial construction. Although many architects find

21584-540: Was bombed on: B-29s were withdrawn from airfields in China by the end of January 1945. Throughout the prior period, B-29 raids were also launched from China and India against many other targets throughout Southeast Asia , including a series of raids on Singapore and Thailand. On 2 November 1944, 55 B-29s raided Bangkok's Bang Sue marshaling yards in the largest raid of the war. Seven RTAF Nakajima Ki-43 Hayabusa s from Foong Bin (Air Group) 16 and 14 IJAAF Ki-43s attempted intercept. RTAF Flt Lt Therdsak Worrasap attacked

21736-600: Was directed by William F. Durand from 1916. Parameters measured included propeller efficiency, thrust developed, and power absorbed. While a propeller may be tested in a wind tunnel , its performance in free-flight might differ. At the Langley Memorial Aeronautical Laboratory , E. P. Leslie used Vought VE-7s with Wright E-4 engines for data on free-flight, while Durand used reduced size, with similar shape, for wind tunnel data. Their results were published in 1926 as NACA report #220. Lowry quotes

21888-435: Was extended to public supply contracts by the then European Communities' Directive 77/62/EEC coordinating procedures for the award of public supply contracts, adopted in 1976. Some organisations provide guidance on specification-writing for their staff and partners. In addition to identifying the specific attributes required of the goods or services being purchased, specifications in the public sector may also make reference to

22040-797: Was followed in 1947 by its commercial airliner variant, the Boeing Model 377 Stratocruiser . This bomber-to-airliner derivation was similar to the B-17 / Model 307 evolution. In 1948, Boeing introduced the KB-29 tanker, followed in 1950 by the Model 377-derivative KC-97 . A line of outsized-cargo variants of the Stratocruiser is the Guppy  / Mini Guppy  / Super Guppy , which remain in service with NASA and other operators. The Soviet Union produced 847 Tupolev Tu-4s , an unlicensed reverse-engineered copy of

22192-447: Was partially stalled on take-off and up to 160 mph (260 km/h) on its way up to a top speed of 407.5 mph (655.8 km/h). The very wide speed range was achieved because some of the usual requirements for aircraft performance did not apply. There was no compromise on top-speed efficiency, the take-off distance was not restricted to available runway length and there was no climb requirement. The variable pitch blades used on

22344-569: Was replaced in its primary role during the early 1950s by the Boeing B-47 Stratojet , which in turn was replaced by the Boeing B-52 Stratofortress . The final active-duty KB-50 and WB-50 variants were phased out in the mid-1960s, with the final example retired in 1965. A total of 3,970 B-29s were built. The variants of the B-29 were outwardly similar in appearance but were built around different wing center sections that affected

22496-513: 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

22648-515: Was shot down by a B-29 during the war. This occurred on 6 December 1950, when a B-29 shot down Lieutenant N. Serikov. With the arrival of the mammoth Convair B-36 , the B-29 was reclassified as a medium bomber by the Air Force. The later B-50 Superfortress variant (initially designated B-29D ) was able to handle auxiliary roles such as air-sea rescue , electronic intelligence gathering, air-to-air refueling , and weather reconnaissance . The B-50D

22800-595: Was the engines. Although the Wright R-3350 Duplex-Cyclone radial engines later became a trustworthy workhorse in large piston-engined aircraft, early models were beset with dangerous reliability problems. This problem was not fully cured until the aircraft was fitted with the more powerful Pratt & Whitney R-4360 "Wasp Major" in the B-29D /B-50 program, which arrived too late for World War II . Interim measures included cuffs placed on propeller blades to divert

22952-541: Was the first attack on Japanese islands since the Doolittle raid in April 1942. The first B-29 combat losses occurred during this raid, with one B-29 destroyed on the ground by Japanese fighters after an emergency landing in China, one lost to anti-aircraft fire over Yawata, and another, the Stockett's Rocket (after Capt. Marvin M. Stockett, Aircraft Commander) B-29-1-BW 42-6261, disappeared after takeoff from Chakulia, India, over

23104-403: Was to check the magnetos while already on takeoff roll rather than during a conventional static engine-runup before takeoff. In wartime, the B-29 was capable of flight at altitudes up to 31,850 feet (9,710 m), at speeds of up to 350 mph (560 km/h; 300 kn) ( true airspeed ). This was its best defense because Japanese fighters could barely reach that altitude, and few could catch

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