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73-575: In June 1940, the Curtiss-Wright company received an Army contract for preliminary engineering data and a powered wind tunnel model. The designation 'P-55' was reserved for the project. The exhaustive wind-tunnel tests that from November 1940 through January 1941 left the USAAC dissatisfied with the results of these tests. Accordingly, Curtiss-Wright built at their St Louis division a flying full-scale mockup they designated CW-24B. The flying testbed

146-505: A whirling arm apparatus to determine drag and did some of the first experiments in aviation theory. Sir George Cayley (1773–1857) also used a whirling arm to measure the drag and lift of various airfoils. His whirling arm was 5 feet (1.5 m) long and attained top speeds between 10 and 20 feet per second (3 to 6 m/s). Otto Lilienthal used a rotating arm to accurately measure wing airfoils with varying angles of attack , establishing their lift-to-drag ratio polar diagrams, but

219-574: A 50 km (31 mi) course around the water tower, the McCook Field water tower, and a pylon placed at New Carlisle . In June 1923, an Air Service TC-1 airship "was wrecked in a storm at Wilbur Wright Field" and by 1924, the field had "an interlock system" radio beacon using Morse code command guidance (dash-dot "N" for port, dot-dash "A" for starboard) illuminating instrument board lights. The Field Service Section at Wilbur Wright Field merged with McCook's Engineering Division to form

292-516: A centrifugal blower in 1897, and determined the drag coefficients of flat plates, cylinders and spheres. Danish inventor Poul la Cour applied wind tunnels in his process of developing and refining the technology of wind turbines in the early 1890s. Carl Rickard Nyberg used a wind tunnel when designing his Flugan from 1897 and onwards. In a classic set of experiments, the Englishman Osborne Reynolds (1842–1912) of

365-483: A factor), and so is not directly useful for accurate measurements. The air moving through the tunnel needs to be relatively turbulence-free and laminar . To correct this problem, closely spaced vertical and horizontal air vanes are used to smooth out the turbulent airflow before reaching the subject of the testing. Due to the effects of viscosity , the cross-section of a wind tunnel is typically circular rather than square, because there will be greater flow constriction in

438-497: A flexible strip. The strip is attached to the aerodynamic surface with tape, and it sends signals depicting the pressure distribution along its surface. Pressure distributions on a test model can also be determined by performing a wake survey , in which either a single pitot tube is used to obtain multiple readings downstream of the test model, or a multiple-tube manometer is mounted downstream and all its readings are taken. The aerodynamic properties of an object can not all remain

511-405: A pair of fans driven by 4,000 hp (3,000 kW) electric motors. The layout was a double-return, closed-loop format and could accommodate many full-size real aircraft as well as scale models. The tunnel was eventually closed and, even though it was declared a National Historic Landmark in 1995, demolition began in 2010. Until World War II, the world's largest wind tunnel, built in 1932–1934,

584-485: A slow roll, but lost altitude and crashed, sending flaming debris into occupied civilian ground vehicles on a highway near the airfield. The crash killed Glasgow and four civilians on the ground. In test flights the XP-55 achieved 390 mph at 19,300 feet but there were engine cooling problems. In terms of overall performance, testing of the XP-55 revealed it to be inferior to conventional fighter aircraft. In addition, by

657-417: A tube, and air is blown around it to study the interaction between the object and the moving air. They are used to test the aerodynamic effects of aircraft , rockets , cars , and buildings . Different wind tunnels range in size from less than a foot across, to over 100 feet (30 m), and can have air that moves at speeds from a light breeze to hypersonic velocities. Usually, large fans move air through

730-431: A wind tunnel type of test during an actual flight in order to refine the computational model. Where external turbulent flow is present, CFD is not practical due to limitations in present-day computing resources. For example, an area that is still much too complex for the use of CFD is determining the effects of flow on and around structures, bridges, and terrain. The most effective way to simulative external turbulent flow

803-405: Is blown or sucked through a duct equipped with a viewing port and instrumentation where models or geometrical shapes are mounted for study. Typically the air is moved through the tunnel using a series of fans. For very large wind tunnels several meters in diameter, a single large fan is not practical, and so instead an array of multiple fans are used in parallel to provide sufficient airflow. Due to

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876-527: Is for understanding exhaust gas dispersion patterns for hospitals, laboratories, and other emitting sources. Other examples of boundary layer wind tunnel applications are assessments of pedestrian comfort and snow drifting. Wind tunnel modeling is accepted as a method for aiding in green building design. For instance, the use of boundary layer wind tunnel modeling can be used as a credit for Leadership in Energy and Environmental Design (LEED) certification through

949-416: Is particularly important in open cockpit race cars such as Indycar and Formula One. Excessive lift forces on the helmet can cause considerable neck strain on the driver, and flow separation on the back side of the helmet can cause turbulent buffeting and thus blurred vision for the driver at high speeds. The advances in computational fluid dynamics (CFD) modelling on high-speed digital computers has reduced

1022-409: Is through the use of a boundary layer wind tunnel. There are many applications for boundary layer wind tunnel modeling. For example, understanding the impact of wind on high-rise buildings, factories, bridges, etc. can help building designers construct a structure that stands up to wind effects in the most efficient manner possible. Another significant application for boundary layer wind tunnel modeling

1095-547: The Materiel Division on 15 October 1926 ("moved to Wright Field when McCook Field closed in 1927"). The Air Service's "control station for the model airway"—which scheduled military flights of the Airways Section —moved to Wilbur Wright Field from McCook Field in the late 1920s (originally "at Bolling Field until 1925"). The Fairfield Air Depot formed when the leased area of Wilbur Wright Field and

1168-589: The United States Army Air Forces issued a contract for three prototypes under the designation XP-55. Serial numbers 42-78845 through 42-78847 were assigned to the aircraft. During this time, the Pratt & Whitney X-1800 H-block sleeve valve engine was delayed, and was eventually canceled. Curtiss decided to switch to the 1,000 hp (750 kW) Allison V-1710 (F16) liquid-cooled inline engine because of its proven reliability. Armament

1241-531: The University of Manchester demonstrated that the airflow pattern over a scale model would be the same for the full-scale vehicle if a certain flow parameter were the same in both cases. This factor, now known as the Reynolds number , is a basic parameter in the description of all fluid-flow situations, including the shapes of flow patterns, the ease of heat transfer, and the onset of turbulence. This comprises

1314-417: The static pressure , and (for compressible flow only) the temperature rise in the airflow. The direction of airflow around a model can be determined by tufts of yarn attached to the aerodynamic surfaces. The direction of airflow approaching a surface can be visualized by mounting threads in the airflow ahead of and aft of the test model. Smoke or bubbles of liquid can be introduced into the airflow upstream of

1387-413: The 1960s, wind tunnel testing began to receive widespread adoption for automobiles , not so much to determine aerodynamic forces in the same way as an airplane, but to increase the fuel efficiency of vehicles by reducing the aerodynamic drag. In these studies, the interaction between the road and the vehicle plays a significant role, and this interaction must be taken into consideration when interpreting

1460-514: The Army's Scott Field near the Curtiss-Wright plant in St Louis, Missouri . The pilot was J. Harvey Gray, Curtiss' test pilot. Testing revealed the takeoff run was excessively long. To solve this problem, the nose elevator size was increased and the aileron up-trim was interconnected with the flaps so it operated after the flaps were lowered. In 15 November 1943, test pilot Harvey Gray, flying

1533-749: The Army-owned land of the Fairfield Aviation General Supply Depot merged soon after World War I. For an aerial war game of 1929, "Fairfield" was the headquarters of the Blue air force: a Blue "airdrome north of Dayton at Troy" was strafed on May 16 ("a raid on the airdrome at Fairfield" was later expected), "Dayton" was the May 21 take off site for a round-trip bomber attack on New York , and "target areas at Fairfield" were used for live bombing on May 25. A provisional division

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1606-784: The Miami Conservancy District. Logistics support to Wilbur Wright Field was by the adjacent Fairfield Aviation General Supply Depot established in January 1918 and which also supplied three other Midwest Signal Corps aviation schools. A Signal Corps Aviation School began in June 1917 for providing combat pilots to the Western Front in France, and the field housed an aviation mechanic's school and an armorer's school. On 19 June 1918, Lt. Frank Stuart Patterson at

1679-523: The U.S. Green Building Council. Wind tunnel tests in a boundary layer wind tunnel allow for the natural drag of the Earth's surface to be simulated. For accuracy, it is important to simulate the mean wind speed profile and turbulence effects within the atmospheric boundary layer. Most codes and standards recognize that wind tunnel testing can produce reliable information for designers, especially when their projects are in complex terrain or on exposed sites. In

1752-466: The United States as part of the plan to exploit German technology developments. For limited applications, computational fluid dynamics (CFD) can supplement or possibly replace the use of wind tunnels. For example, the experimental rocket plane SpaceShipOne was designed without any use of wind tunnels. However, on one test, flight threads were attached to the surface of the wings, performing

1825-403: The United States, many wind tunnels have been decommissioned from 1990 to 2010, including some historic facilities. Pressure is brought to bear on remaining wind tunnels due to declining or erratic usage, high electricity costs, and in some cases the high value of the real estate upon which the facility sits. On the other hand, CFD validation still requires wind-tunnel data, and this is likely to be

1898-589: The above, however, that they were simply using the accepted technology of the day, though this was not yet a common technology in America. In France , Gustave Eiffel (1832–1923) built his first open-return wind tunnel in 1909, powered by a 67 hp (50 kW) electric motor, at Champs-de-Mars, near the foot of the tower that bears his name. Between 1909 and 1912 Eiffel ran about 4,000 tests in his wind tunnel, and his systematic experimentation set new standards for aeronautical research. In 1912 Eiffel's laboratory

1971-484: The air standing still and an aircraft moving, an object would be held still and the air moved around it. In this way, a stationary observer could study the flying object in action, and could measure the aerodynamic forces acting on it. The development of wind tunnels accompanied the development of the airplane. Large wind tunnels were built during World War II, and as supersonic aircraft were developed, supersonic wind tunnels were constructed to test them. Wind tunnel testing

2044-763: The airfield was testing machine gun/propeller synchronization when a tie rod failure broke the wings off his Airco DH.4 M while diving from 15,000 ft (4,600 m). Also in 1918, McCook Field near Dayton between Keowee Street and the Great Miami River began using space and mechanics at Wilbur Wright Field. Following World War I, the training school at Wilbur Wright Field was discontinued. Training units assigned to Wilbur Wright Field Combat units trained at Wilbur Wright Field Service units trained at Wilbur Wright Field   1923 records for speed, distance, and endurance were set by an April 16 Fokker T-2 flight from Wilbur Wright Field which used

2117-400: The airstream to show the path that air takes around the object. Or, small threads can be attached to specific parts to show the airflow at those points. The earliest wind tunnels were invented towards the end of the 19th century, in the early days of aeronautical research, as part of the effort to develop heavier-than-air flying machines. The wind tunnel reversed the usual situation. Instead of

2190-638: The answers out of a wind tunnel." In 1941 the US constructed one of the largest wind tunnels at that time at Wright Field in Dayton, Ohio. This wind tunnel starts at 45 feet (14 m) and narrows to 20 feet (6.1 m) in diameter. Two 40-foot (12 m) fans were driven by a 40,000 hp electric motor. Large scale aircraft models could be tested at air speeds of 400 mph (640 km/h). During WWII, Germany developed different designs of large wind tunnels to further their knowledge of aeronautics. For example,

2263-641: The building will collapse. Determining such forces was required before building codes could specify the required strength of such buildings and these tests continue to be used for large or unusual buildings. Wind tunnel testing was first applied to automobiles as early as the 1920s, on cars such as the Rumpler Tropfenwagen , and later the Chrysler Airflow . Initially, automakers would test out scale models of their cars, but later, full scale automotive wind tunnels were built. Starting in

Curtiss-Wright XP-55 Ascender - Misplaced Pages Continue

2336-555: The case for the foreseeable future. Studies have been done and others are underway to assess future military and commercial wind tunnel needs, but the outcome remains uncertain. More recently an increasing use of jet-powered, instrumented unmanned vehicles, or research drones, have replaced some of the traditional uses of wind tunnels. The world's fastest wind tunnel as of 2019 is the LENS-X wind tunnel, located in Buffalo, New York. Air

2409-483: The central scientific justification for the use of models in wind tunnels to simulate real-life phenomena. However, there are limitations on conditions in which dynamic similarity is based upon the Reynolds number alone. The Wright brothers ' use of a simple wind tunnel in 1901 to study the effects of airflow over various shapes while developing their Wright Flyer was in some ways revolutionary. It can be seen from

2482-428: The corners of a square tunnel that can make the flow turbulent. A circular tunnel provides a smoother flow. The inside facing of the tunnel is typically as smooth as possible, to reduce surface drag and turbulence that could impact the accuracy of the testing. Even smooth walls induce some drag into the airflow, and so the object being tested is usually kept near the center of the tunnel, with an empty buffer zone between

2555-403: The demand for wind tunnel testing, but has not completely eliminated it. Many real-world problems can still not be modeled accurately enough by CFD to eliminate the need for physical tests in wind tunnels. Air velocity and pressures are measured in several ways in wind tunnels. Air velocity through the test section is determined by Bernoulli's principle . Measurement of the dynamic pressure ,

2628-414: The direction of smoke from a ship's stack, to whether a given airplane would fly. Progress at Aachen, I felt, would be virtually impossible without a good wind tunnel. When von Kármán began to consult with Caltech he worked with Clark Millikan and Arthur L. Klein. He objected to their design and insisted on a return flow making the device "independent of the fluctuations of the outside atmosphere". It

2701-753: The end of 1944, German and British jet-powered fighters were fully operational, and the Lockheed XP-80 was about to commence operational trials with USAAF units in Italy. Development of completely new piston-engine fighter designs was regarded as redundant; further development of such aircraft was terminated, including the XP-55. Data from Green and Swanborough 1977 Air and Space Museum General characteristics Performance Armament Aircraft of comparable role, configuration, and era Related lists Wind tunnel Wind tunnels are machines in which objects are held stationary inside

2774-416: The end of the war, Germany had at least three different supersonic wind tunnels, with one capable of Mach 4.4 (heated) airflows. A large wind tunnel under construction near Oetztal , Austria would have had two fans directly driven by two 50,000 horsepower hydraulic turbines . The installation was not completed by the end of the war and the dismantled equipment was shipped to Modane , France in 1946 where it

2847-408: The first XP-55 (S/N 42-78845), was testing the aircraft's stall performance at altitude. Suddenly, the XP-55 inverted into an uncontrolled descent. The engine failed "making recovery impossible" and it fell out of control for 16,000 ft (4,900 m) before Gray was able to parachute to safety. The aircraft was destroyed and "left a smoking hole in the ground". The second XP-55 (serial 42-78846)

2920-479: The first enclosed wind tunnel in 1871. Once this breakthrough had been achieved, detailed technical data was rapidly extracted by the use of this tool. Wenham and his colleague John Browning are credited with many fundamental discoveries, including the measurement of l/d ratios, and the revelation of the beneficial effects of a high aspect ratio . Konstantin Tsiolkovsky built an open-section wind tunnel with

2993-423: The investigation of the crash of the first prototype were introduced during construction; the addition of four-foot wingtip extensions to improve the stall characteristics and increasing the limits of the nose elevator travel to improve recovery if a stall did occur. It was the only prototype to be fitted with armament - four 0.5-inch machine guns. After the second XP-55 (42-78846) was given the same modifications as

Curtiss-Wright XP-55 Ascender - Misplaced Pages Continue

3066-597: The location of the Materiel Division of the Air Corps and a key logistics center and in 1935, quarters were built at Patterson Field which in 1939 still "was without runways...heavier aircraft met difficulty in landing in inclement weather." Wright Field retained the land west of the Huffman Dam and became the research and development center of the Air Corps. Engineering and flight activities of

3139-426: The object and the tunnel walls. There are correction factors to relate wind tunnel test results to open-air results. Wright Field Wilbur Wright Field was a military installation and an airfield used as a World War I pilot, mechanic, and armorer training facility and, under different designations, conducted United States Army Air Corps and Air Forces flight testing. Located near Riverside, Ohio ,

3212-431: The pressure at each hole. Pressure distributions can more conveniently be measured by the use of pressure-sensitive paint , in which higher local pressure is indicated by lowered fluorescence of the paint at that point. Pressure distributions can also be conveniently measured by the use of pressure-sensitive pressure belts , a recent development in which multiple ultra-miniaturized pressure sensor modules are integrated into

3285-433: The principle of safe fog flying) was moved to Wright Field by the end of 1931. Materiel Division ’s Fog Flying Unit under 1st Lt. Albert F. Hegenberger used the equipment for blind landings. Patterson Field named for Frank Stuart Patterson was designated on 6 July 1931 as the area of Wright Field east of Huffman Dam (including Fairfield Air Depot, Huffman Prairie, and Wright Field's airfield). Patterson Field became

3358-592: The same for a scaled model. However, by observing certain similarity rules, a very satisfactory correspondence between the aerodynamic properties of a scaled model and a full-size object can be achieved. The choice of similarity parameters depends on the purpose of the test, but the most important conditions to satisfy are usually: In certain particular test cases, other similarity parameters must be satisfied, such as e.g. Froude number . English military engineer and mathematician Benjamin Robins (1707–1751) invented

3431-665: The school year 1927-28 at Wright Field, which had the Army Air Corps Museum in Building 12. By November 1930, "the laboratory at Wright Field" had planes fitted as flying laboratories" (e.g., B-19 "flying laboratory" with "8-foot tires"), and the equipment of the 1929 Full Flight Laboratory (closed out by the Daniel Guggenheim Fund for the Promotion of Aeronautics , which had established

3504-403: The sheer volume and speed of air movement required, the fans may be powered by stationary turbofan engines rather than electric motors. The airflow created by the fans that is entering the tunnel is itself highly turbulent due to the fan blade motion (when the fan is blowing air into the test section – when it is sucking air out of the test section downstream, the fan-blade turbulence is not

3577-596: The site is officially "Area B" of Wright-Patterson Air Force Base and includes the National Museum of the United States Air Force built on the airfield. Wilbur Wright Field was established in 1917 for World War I on 2,075 acres (840 ha) of land adjacent to the Mad River which included the 1910 Wright Brothers ' Huffman Prairie Flying Field and that was leased to the Army by

3650-491: The southwest (now part of Riverside ). The combined area was named Wright Field to honor both Wright Brothers. A new installation with permanent brick facilities was constructed to replace McCook Field and was dedicated on October 12, 1927. The transfer of 4,500 tons of engineering material, office equipment and other assets at McCook Field to Wright Field began on March 25, 1927, and was 85% complete by June 1 after moving 1,859 truckloads. "The Engineering School shut down for

3723-426: The test model, and their path around the model can be photographed (see particle image velocimetry ). Aerodynamic forces on the test model are usually measured with beam balances , connected to the test model with beams, strings, or cables. The pressure distributions across the test model have historically been measured by drilling many small holes along the airflow path, and using multi-tube manometers to measure

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3796-556: The test results. In the real world, the vehicle is moving while the road and air are stationary. In a wind tunnel test, the road must also be moved past a vehicle along with air being blown around it. This has been accomplished with moving belts under the test vehicle to simulate the moving road, and very similar devices are used in wind tunnel testing of aircraft take-off and landing configurations. Sporting equipment has also studied in wind tunnels, including golf clubs, golf balls, bobsleds, cyclists, and race car helmets. Helmet aerodynamics

3869-649: The third prototype, it underwent official USAAF flight trials between 16 September and 2 October 1944. The third prototype XP-55 (s/n 42-78847) was lost on 27 May 1945, during the closing day of the Seventh War Bond Air Show at the Army Air Forces Fair at Wright Field in Dayton, Ohio . After a low pass in formation with a Lockheed P-38 Lightning and a North American P-51 Mustang on each wing, its pilot, William C. Glasgow, attempted

3942-761: The two installations after the designation of Patterson Field included numerous aviation achievements and failures prior to the bombing of Pearl Harbor : The Army Air Forces Technical Base was formed on December 15, 1945, when Wright Field, Patterson Field, Dayton Army Air Field in Vandalia and Clinton County AAF in Wilmington merged. After the USAF was created, the base was renamed Air Force Technical Base in December 1947 and Wright-Patterson Air Force Base in January 1948.. The former Wright Field became Area B of

4015-459: The wind stream is upwards for the testing of models in spin situations and the concepts and engineering designs for the first primitive helicopters flown in the US. Later research into airflows near or above the speed of sound used a related approach. Metal pressure chambers were used to store high-pressure air which was then accelerated through a nozzle designed to provide supersonic flow. The observation or instrumentation chamber ("test section")

4088-404: The wind tunnel at Peenemünde was a novel wind tunnel design that allowed for high-speed airflow research, but brought several design challenges regarding constructing a high-speed wind tunnel at scale. However, it successfully used some large natural caves which were increased in size by excavation and then sealed to store large volumes of air which could then be routed through the wind tunnels. By

4161-516: The wind tunnel, while the object being tested is held stationary. The object can be an aerodynamic test object such as a cylinder or an airfoil, an individual component of an aircraft, a small model of the vehicle, or, in the largest tunnels, even a full-sized vehicle. Different measurements can be taken from these tests. The aerodynamic forces on the entire object can be measured, or on individual components of it. The air pressure at different points can be measured with sensors. Smoke can be introduced into

4234-583: The world at that time at the Washington Navy Yard. The inlet was almost 11 feet (3.4 m) in diameter and the discharge part was 7 feet (2.1 m) in diameter. A 500 hp (370 kW) electric motor drove the paddle type fan blades. In 1931 the NACA built a 30 by 60 feet (9.1 by 18.3 m) full-scale wind tunnel at Langley Research Center in Hampton, Virginia. The tunnel was powered by

4307-550: Was Theodore von Kármán 's teacher at Göttingen University and suggested the construction of a wind tunnel for tests of airships they were designing. The vortex street of turbulence downstream of a cylinder was tested in the tunnel. When he later moved to Aachen University he recalled use of this facility: I remembered the wind tunnel in Göttingen was started as a tool for studies of Zeppelin behavior, but that it had proven to be valuable for everything else from determining

4380-593: Was "assembled at Dayton" on May 16, 1931, for maneuvers in which "Maj. Henry H. Arnold , division G-4 (Supply), had stocks at Pittsburgh; Cleveland; Buffalo; Middletown, Pennsylvania; Aberdeen, Maryland; and Bolling Field to service units as they flew eastward." The depot remained active until 1946. In 1924, the city of Dayton purchased 4,500 acres (1,821 ha), the portion of Fairfield Air Depot leased in 1917 for Wilbur Wright Field, along with an additional 750 acres (300 ha) in Montgomery County to

4453-460: Was an arrangement followed by a number of wind tunnels later built; in fact the open-return low-speed wind tunnel is often called the Eiffel-type wind tunnel. Subsequent use of wind tunnels proliferated as the science of aerodynamics and discipline of aeronautical engineering were established and air travel and power were developed. The US Navy in 1916 built one of the largest wind tunnels in

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4526-471: Was completed in 1930 and used for Northrop Alpha testing. In 1939 General Arnold asked what was required to advance the USAF, and von Kármán answered, "The first step is to build the right wind tunnel." On the other hand, after the successes of the Bell X-2 and prospect of more advanced research, he wrote, "I was in favor of constructing such a plane because I have never believed that you can get all

4599-493: Was considered of strategic importance during the Cold War for development of aircraft and missiles. Other problems are also studied with wind tunnels. The effects of wind on man-made structures need to be studied when buildings became tall enough to be significantly affected by the wind. Very tall buildings present large surfaces to the wind, and the resulting forces have to be resisted by the building's internal structure or else

4672-415: Was invented by W. Jerome Peterson while working as a design engineer for Curtiss-Wright. Three XP-55 prototypes were built. Two were destroyed during flight testing, as a result of their propensity for sudden wing stalls . The first XP-55 (42-78845) was completed and delivered on 13 July 1943, with the same configuration as the final prototype CW-24B. The aircraft made its first flight on 19 July 1943 from

4745-551: Was lacking the notions of induced drag and Reynolds numbers . However, the whirling arm does not produce a reliable flow of air impacting the test shape at a normal incidence. Centrifugal forces and the fact that the object is moving in its own wake mean that detailed examination of the airflow is difficult. Francis Herbert Wenham (1824–1908), a Council Member of the Aeronautical Society of Great Britain , addressed these issues by inventing, designing and operating

4818-456: Was located in a suburb of Paris, Chalais-Meudon , France. It was designed to test full-size aircraft and had six large fans driven by high powered electric motors. The Chalais-Meudon wind tunnel was used by ONERA under the name S1Ch until 1976 in the development of, e.g., the Caravelle and Concorde airplanes. Today, this wind tunnel is preserved as a national monument. Ludwig Prandtl

4891-412: Was moved to Auteuil, a suburb of Paris, where his wind tunnel with a two-metre test section is still operational today. Eiffel significantly improved the efficiency of the open-return wind tunnel by enclosing the test section in a chamber, designing a flared inlet with a honeycomb flow straightener and adding a diffuser between the test section and the fan located at the downstream end of the diffuser; this

4964-425: Was poured on 22 June 1942 on a site that eventually would become Calspan , where the wind tunnel still operates. By the end of World War II, the US had built eight new wind tunnels, including the largest one in the world at Moffett Field near Sunnyvale, California, which was designed to test full size aircraft at speeds of less than 250 mph (400 km/h) and a vertical wind tunnel at Wright Field, Ohio, where

5037-591: Was powered by a 275 hp (205 kW) Menasco C68-5 inline engine. It had a fabric-covered , welded steel tube fuselage with a wooden wing. The undercarriage was non-retractable. The canard did not carry load but only trimmed flight. The CW-24B model completed its maiden flight in December 1941. From November 1941 to May 1942, the Model 24B logged 169 flights at Muroc Dry Lake , California. The tests appeared to show potential. The CW-24B then went to NACA at Langley Field for wind tunnel tests. On 10 July 1942,

5110-469: Was re-erected and is still operated there by the ONERA . With its 26 ft (8 m) test section and airspeed up to Mach 1, it is the largest transonic wind tunnel facility in the world. Frank Wattendorf reported on this wind tunnel for a US response. On 22 June 1942, Curtiss-Wright financed construction of one of the nation's largest subsonic wind tunnels in Buffalo, NY. The first concrete for building

5183-421: Was similar to the first, but with a slightly larger nose-elevator, modified elevator-tab systems, and a change from balance tabs to spring tabs on the ailerons. It flew for the first time on 9 January 1944. All flight tests were restricted so the stall-zone was avoided; included no stalling below 20,000 ft. The third XP-55 (serial 42-78847) flew for the first time on 25 April 1944. Modifications resulting from

5256-560: Was then placed at the proper location in the throat or nozzle for the desired airspeed. In the United States, concern over the lagging of American research facilities compared to those built by the Germans led to the Unitary Wind Tunnel Plan Act of 1949, which authorized expenditure to construct new wind tunnels at universities and at military sites. Some German war-time wind tunnels were dismantled for shipment to

5329-444: Was to be two 20 mm (0.79 in) Hispano autocannon and two 0.50 in (12.7 mm) M2 Bowning heavy machine guns . During the mock-up phase, engineers switched to the 1,275 hp (951 kW) V-1710-95. The 20mm cannons were also replaced by 0.50-in machine guns. One feature of the XP-55 was a propeller jettison lever inside the cockpit to prevent the pilot from hitting the propeller during bailout. The jettison device

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