The Curtiss P-60 was a 1940s American single-engine single-seat, low-wing monoplane fighter aircraft developed by the Curtiss-Wright company as a successor to their P-40 . It went through a lengthy series of prototype versions, eventually evolving into a design that bore little resemblance to the P-40. None of these versions reached production.
147-588: Following rejection of the XP-46, Curtiss put forward their Model 88 in proposals to the United States Army Air Corps . was for an aircraft using the P-40D fuselage and tail assembly with a low drag NACA laminar flow wing, the (at the time under development) Continental I-1430 -3 inverted V-12 engine, and eight wing-mounted 0.5 in (12.7 mm) machine guns. This proposal was accepted and
294-617: A "fiasco" in the media, investigating boards in 1933–1934 recommended organizational and modernization changes that again set the Air Corps on the path to autonomy and eventual separation from the Army. A force of 2,320 aircraft was recommended by the Drum Board, and authorized by Congress in June 1936, but appropriations to build up the force were denied by the administration until 1939, when
441-615: A "team player". The open insurgency between 1920 and 1935 of airmen foreseeing a need for an independent air force in order to develop fully the potential of airpower had cost the careers of two of its near-legendary lights, Foulois and Mitchell, and nearly cost the reputation of two others, Pratt and Henry H. Arnold . In terms of the principle of civilian control of the military in peacetime, their tactics and behavior were clearly inappropriate. The political struggle had temporarily alienated supporters in Congress, had been counterproductive of
588-515: A 36-week course for junior and mid-career officers that included military aviation theory. The Bombardment Section, under the direction of its chief, Major Harold L. George , became influential in the development of doctrine and its dissemination throughout the Air Corps. Nine of its instructors became known throughout the Air Corps as the " Bomber Mafia ", eight of whom (including George) went on to be generals during World War II. Conversely, pursuit tacticians, primarily Capt. Claire Chennault , Chief of
735-794: A base. As their numbers and utility declined, they were replaced by a series of 50 twin-engine and single-engine small transports and used for staff duties. Pilot training was conducted between 1927 and 1937 in the Consolidated PT-3 trainer, followed by the Stearman PT-13 and variants after 1937. By 1933 the Air Corps expanded to a tactical strength of 50 squadrons: 21 pursuit, 13 observation, 12 bombardment, and 4 attack. All were understrength in aircraft and men, particularly officers, which resulted in most being commanded by junior officers (commonly first lieutenants) instead of by majors as authorized. The last open-cockpit fighter used by
882-464: 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
1029-569: A bright spot. The first action to repair the damaged image of the Air Corps involved the movement of ten YB-10s from Bolling Field to Alaska, ostensibly for an airfield survey, but timed to coincide with the release of the Baker Board's report in July. The successful development of the B-10 and subsequent orders for more than 150 (including its B-12 variant) continued the hegemony of the bomber within
1176-473: 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
1323-613: A contract for two prototypes was issued on 1 October 1940 with the aircraft designated XP-53 . Within two months the Army Air Corps contacted Curtiss for an aircraft with a laminar wing and the British Rolls Royce Merlin engine. Curtiss suggested the XP-53 design be used and the second prototype be converted while it was being built; the contract was altered to account for that with the aircraft - known to
1470-461: 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
1617-416: 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
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#17327867066941764-534: A four-bladed propeller. As a result of the other prototype variants, this modification was redesignated XP-60E (Model 95D) . On 27 January 1943, the XP-60C flew for the first time, powered by an R-2800-53 engine with contra-rotating propellers. The aircraft's flying characteristics were found to be generally satisfactory. The first flight of the XP-60E with the four-bladed propeller was delayed until 26 May 1943 after it
1911-659: A group of General Staff officers, recommended in 1923 that the Air Service be augmented by an offensive force of bombardment and pursuit units under the command of Army general headquarters in time of war, and many of its recommendations became Army regulations. The War Department desired to implement the Lassiter Board's recommendations, but the administration of President Calvin Coolidge chose instead to economize by radically cutting military budgets, particularly
2058-510: A lack of legally specified duties and responsibilities, the new position of Assistant Secretary of War for Air , held by F. Trubee Davison from July 1926 to March 1933, proved of little help in promoting autonomy for the air arm. The Air Corps Act gave authorization to carry out a five-year expansion program. However, a lack of appropriations caused the beginning of the program to be delayed until 1 July 1927. Patrick proposed an increase to 63 tactical squadrons (from an existing 32) to maintain
2205-467: 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
2352-580: A long-range capability for these new single-engined fighters was not undertaken until combat losses of bombers forced the issue. Notable fighters developed during the late 1930s and early 1940s were the Bell P-39 Airacobra (first flown April 1938), Curtiss P-40 Warhawk (October 1938), Lockheed P-38 Lightning (January 1939), North American P-51 Mustang (October 1940), and Republic P-47 Thunderbolt (May 1941). Technological development of fighters occurred so rapidly that by December 1941 both
2499-528: 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
2646-696: A modification of the Joint Action statement on coastal defense issued in 1926, was not endorsed by the Joint Army-Navy Board and never had authority other than a personal agreement between the two heads of service. Though the Navy repudiated the statement when Pratt retired in 1934, the Air Corps clung to the mission, and provided itself with the basis for development of long-range bombers and creating new doctrine to employ them. The formulation of theories of strategic bombing gave new impetus to
2793-574: A plan that would have included the purchase of 144 four-engine bombers but approval was reversed in July when the moratorium against the long-range bomber program was imposed by the Joint Board. The purchase of 67 B-17s (five squadrons) in FY 1940 as an increment of the Woodring program, using carryover funds, was cancelled by Craig. The moratorium also resulted from the enmity of the Navy incurred by
2940-582: A profusion of pursuit, observation, and bomber aircraft during its 15-year history. The advent of the new generation of monoplanes and the emergence of strategic bombardment doctrine led to many designs in the mid and late 1930s that were still in use when the United States entered World War II . Among the key technology items developed were oxygen and cabin pressurization systems, engine superchargers (systems essential for high-altitude combat), advanced radio communication systems, such as VHF radios, and
3087-415: 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
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#17327867066943234-453: 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
3381-516: A revision of the doctrinal guide for the Air Corps, training regulation TR 440-15 Employment of the Air Forces of the Army . A year earlier MacArthur had changed TR 440-15 to clarify "the Air Corps's place in the scheme of national defense and ... (to do away with) ... misconceptions and interbranch prejudices." The General Staff characterized its latest revision as a "compromise" with airpower advocates, to mitigate public criticism of
3528-434: A ruling that it could foresee no use for a long-range bomber in future conflict. As a direct result, the last planned order of long-range bombers (67 B-17s) was cancelled by Craig and a moratorium on further development of them was put into effect by restricting R&D funding to medium and light bombers. This policy would last less than a year, as it went against not only the trends of technological development, but against
3675-454: 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
3822-583: A small coaxial modeled after the Chinese top but powered by 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
3969-551: A smooth wing surface when the gear was retracted. This aircraft first flew on 18 September 1941 with a British Merlin 28 engine. The XP-53 prototype was then converted into a static test airframe for the XP-60. Considering delivery delays of quantities of the Packard-built Merlin engines might occue due to its use in other fighter projects closer to delivery, the use of a turbo-supercharged Allison V-1710 -75 engine
4116-417: 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
4263-542: A subordinate element of Army General Headquarters, which would be activated to control all Army units in case of war mobilization. In anticipation of military intervention in Cuba in 1933, the headquarters had been created on 1 October but not staffed. The Drum Board of 1933 had first endorsed the concept, but as a means of reintegrating the Air Corps into control by the General Staff, in effect reining it in. Among
4410-698: A swirling slipstream which pushes the propeller forwards or backwards. It comprises a rotating power-driven hub, to which are attached several radial airfoil -section blades such that the whole assembly rotates about a longitudinal axis. The blade pitch may be fixed, manually variable to a few set positions, or of the automatically variable "constant-speed" type. 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
4557-437: A thirteenth aircraft for stress testing, with deliveries made from January to August 1937. The cost of the aircraft disturbed Secretary of War Harry Woodring , who denied requests for further purchases, so that although the air arm embraced strategic bombing as its primary doctrine after the creation of GHQ Air Force, by 1938 there were still only thirteen strategic bombers on hand. On 18 March 1938 Secretary Woodring implemented
Curtiss P-60 - Misplaced Pages Continue
4704-455: 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
4851-479: 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
4998-409: 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
5145-489: 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
5292-454: The 3rd Attack Wing in 1932, protecting the southern border , at which time the 1st became the 1st Pursuit Wing. The three wings became the foundation of General Headquarters Air Force upon its activation in 1935. The Air Corps adopted a new color scheme for painting its aircraft in 1927, heretofore painted olive drab . The wings and tails of aircraft were painted chrome yellow , with the words "U.S. ARMY" displayed in large black lettering on
5439-607: The Curtiss P-1 Hawk (1926–1930) and Boeing P-12 (1929–1935) families, and before the 1934 introduction of the all-metal monoplane, most front-line bombers were canvas-and-wood variants of the radial engined Keystone LB-6 (60 LB-5A, LB-6 and LB-7 bombers) and B-3A (127 B-3A, B-4A, B-5, and B-6A bombers) designs. Between 1927 and 1934, the Curtiss O-1 Falcon was the most numerous of the 19 different types and series of observation craft and its A-3 variant
5586-545: 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
5733-630: The Materiel Division . Of the new law and organization, however, Wesley F. Craven and James L. Cate in the official history of the United States Army Air Forces concluded that: The bill which was finally enacted purported to be a compromise, but it leaned heavily on the Morrow recommendations. The Air Corps Act of 2 July 1926 effected no fundamental innovation. The change in designation meant no change in status:
5880-578: The McDonnell XF-88B experimental propeller-equipped aircraft. Supersonic tip-speeds are used in some aircraft like 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
6027-656: The Norden bombsight . As a further consequence of the Air Mail scandal, the Baker Board reviewed the performance of Air Corps aircraft and recognized that civilian aircraft were far superior to planes developed solely to Air Corps specifications. Following up on its recommendation, the Air Corps purchased and tested a Douglas DC-2 as the XC-32, which subsequently became the flying headquarters of Gen. Andrews. The DC-2 so exceeded Air Corps specifications that 17 were purchased under
Curtiss P-60 - Misplaced Pages Continue
6174-600: The North American P-51 Mustang , which was then flying), and lower than specified engine output performance. The P-60A Allison engine was not delivering the requisite 1,500 hp, and now that America was at war following the Japanese attack on Pearl Harbor, delivery of existing designs took precedence over introducing a new design into production. Work on the P-60A was stopped after 20 December 1941, when
6321-403: 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
6468-481: The tables of organization . Administratively it organized the forces into four geographical districts (which later became the first four numbered air forces) that paralleled the four field army headquarters created in 1933. The General Staff perceived its creation as a means of lessening Air Corps autonomy, not increasing it, however, and GHQ Air Force was a "coordinate component" equal to the Air Corps, not subject to its control. The organizations reported separately to
6615-430: The " Prop and Wings " as its branch insignia through its disestablishment in 1947. Patrick became Chief of the Air Corps and Brig. Gen. James E. Fechet continued as his first assistant chief. On 17 July 1926, two lieutenant colonels were promoted to brigadier general for four-year terms as assistant chiefs of Air Corps: Frank P. Lahm , to command the new Air Corps Training Center , and William E. Gillmore, in command of
6762-665: The AAF came into being in June 1941. Three other long-range bombers began development during this period, though only mock-ups were produced before World War II: the B-29 (study begun in 1938), the Consolidated B-32 Dominator (June 1940), and the Convair B-36 Peacemaker (April 1941). In a special message to Congress on 12 January 1939, President Roosevelt advised that the threat of a new war made
6909-457: The Air Corps had obtained a mission in coastal defense that justified both the creation of a centralized strike force and the development of four-engined bombers, and over the resistance of the General Staff lobbied for another mission, strategic bombardment, with which it could persuasively argue for independence from the Army. The cost of the General Staff's resistance in terms of preparedness had been severe, however. Its policies had resulted in
7056-470: The Air Corps increased in number, so did higher command echelons. The 2nd Wing , activated in 1922 as part of the Air Service, remained the only wing organization in the new Air Corps until 1929, when it was redesignated the 2nd Bombardment Wing in anticipation of the activation of the 1st Bombardment Wing , providing a bombardment wing on each coast. The 1st Bomb Wing was activated in 1931, followed by
7203-542: The Air Corps on 12 May 1938 when it widely publicized the interception of the Italian ocean liner Rex by three B-17s while it was 610 nautical miles (1,100 km) off-shore of New York City. Possibly under pressure from the Navy, Craig placed a limit of 100 nautical miles (190 km) on all future off-shore flights by the Army. The services together issued a revised Joint Action statement in November reasserting that
7350-626: The Air Corps that resulted in a feasibility study for a 35-ton 4-engined bomber (the Boeing XB-15 ). While it was later found to be unsuitable for combat because the power of existing engines was inadequate for its weight, the XB-15 led to the design of the smaller Model 299, later to become the Boeing B-17 Flying Fortress , whose first flight was at the end of July 1935. By that time the Air Corps had two projects in place for
7497-549: The Air Corps was still a combatant branch of the Army with less prestige than the Infantry. The position of the air arm within the Department of War remained essentially the same as before, that is, the flying units were under the operational control of the various ground forces corps area commands and not the Air Corps, which remained responsible for procurement and maintenance of aircraft, supply, and training. Because of
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#17327867066947644-533: The Air Corps, the Boeing P-26 Peashooter , came into service in 1933 and bridged the gap between the biplane and more modern fighters. The Air Corps was called upon in early 1934 to deliver mail in the wake of the Air Mail scandal , involving the postmaster general and heads of the airlines. Despite an embarrassing performance that resulted from numerous crashes and 13 fatalities and was deemed
7791-470: The Air Corps. The separation of the Air Corps from control of its combat units caused problems of unity of command that became more acute as the Air Corps enlarged in preparation for World War II. This was resolved by the creation of the Army Air Forces (AAF), making both organizations subordinate to the new higher echelon. On 20 June 1941 , the Army Air Corps' existence as the primary air arm of
7938-509: The Allison V-1710-75 engine and a Wright SU-504-1 turbo-supercharger, and one XP-60C (Model 95C) with the 2,500 hp 36.4 liter displacement Chrysler XIV-2220 16-cylinder V-16 engine . While the wing of the XP-60 would be used, the fuselage was more rounded in cross-section. In February 1942, the production of P-60As was cancelled so that Curtiss could build a further 1,400 P-40s and - to keep its production lines occupied until
8085-624: The Army , on 15 April 1940. In the fall of 1937, the Army War College 's course on the use of airpower reiterated the General Staff position and taught that airpower was of limited value when employed independently. Using attaché reports from both Spain and Ethiopia , and endorsed by a senior Air Corps instructor, Col. Byron Q. Jones , the course declared that the Flying Fortress concept had "died in Spain", and that airpower
8232-601: The Army until 1947, when it was legally abolished by legislation establishing the Department of the Air Force . The Air Corps was renamed by the United States Congress largely as a compromise between the advocates of a separate air arm and those of the traditionalist Army high command who viewed the aviation arm as an auxiliary branch to support the ground forces. Although its members worked to promote
8379-597: The Army's. The Lampert Committee of the House of Representatives in December 1925 proposed a unified air force independent of the Army and Navy, plus a department of defense to coordinate the three armed services. However another board, headed by Dwight Morrow , was appointed in September 1925 by Coolidge ostensibly to study the "best means of developing and applying aircraft in national defense" but in reality to minimize
8526-539: The B-17 while belatedly recognizing that coordinated air-ground support had been long neglected, decided that it would order only two-engined "light" bombers in fiscal years 1939 through 1941. It also rejected further advancement of Project A, the development program for a very long range bomber. In collaboration with the Navy, the Joint Board (whose senior member was Army Chief of Staff Gen. Malin Craig ) on 29 June 1938 issued
8673-481: The Chief of Staff, the Air Corps as the service element of the air arm, and GHQAF as the tactical element. However, all GHQ Air Force's members, along with members of units stationed overseas and under the control of local ground commanders, remained part of the Air Corps. This dual status and division of authority hampered the development of Air Corps for the next six years, as it had the Air Service during World War I, and
8820-611: The General Staff. The War Plans Division of the Army reacted to the recommendations of the Baker Board by insisting that men and modern equipment for seven army divisions be procured before any increase in the Air Corps was begun, and opposed any immediate attempt to bring the Air Corps up to the 1,800 plane-strength first authorized in 1926, for fear of antagonizing the Navy. President Roosevelt approved an open-ended program to increase strength to 2,320 aircraft (albeit without any proviso for funding) in August 1934, and Secretary Dern approved
8967-535: 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
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#17327867066949114-789: The Joint Action Statement, but the newest revision parroted the anti-autonomy conclusions of the Drum and Baker Boards, and reasserted its long-held position (and that of the Secretary Dern) that auxiliary support of the ground forces was the primary mission of the Air Corps. TR 440-15 did acknowledge some doctrinal principles asserted by the ACTS (including the necessity of destroying an enemy's air forces and concentrating air forces against primary objectives) and recognized that future wars would probably entail some missions "beyond
9261-628: The Military Affairs Committee of the Congress rejected all bills set forth before it on both sides of the issue. They fashioned a compromise in which the findings of the Morrow Board were enacted as law, while providing the air arm a "five-year plan" for expansion and development. Maj. Gen. Mason Patrick , the Chief of Air Service, had proposed that it be made a semi-independent service within the War Department along
9408-581: The Morrow Board's recommendations, the act created an additional Assistant Secretary of War to "help foster military aeronautics", and established an air section in each division of the General Staff for a period of three years. Two additional brigadier generals would serve as assistant chiefs of the Air Corps. Previous provisions of the National Defense Act of 1920 that all flying units be commanded only by rated personnel and that flight pay be awarded were continued. The Air Corps also retained
9555-671: The P-39 and P-40 were approaching obsolescence, even though both had been in production less than 18 months. Bombers developed during this period were the Douglas A-20 Havoc (first flown October 1938), North American B-25 Mitchell (January 1939), Consolidated B-24 Liberator (December 1939), and Martin B-26 Marauder (November 1940). Except for the B-24, P-47, and P-51, all of these had production deliveries that began before
9702-702: The P-60 was ready build - the Thunderbolt for the USAAF. At the time, availability of the Chrysler engine was coming into question, and after Curtiss noted (in April) that either the fuselage would need changes of several hundreds of pounds of ballast would be needed in the tail of the existing airframe to balance the heavy engine, a decision was made in September to install a Pratt & Whitney R-2800 radial engine in
9849-437: The R-2800 engine, resulted in a contract for 500 aircraft, officially designated P-60A-1 , with the R-2800 and contra-rotating propellers ; the first 26 to be YP-60A with single rotation propeller. With concern that the contra-rotating propellers would not be available on time (Pratt & Whitney had to modify the engine gearing), in order to get data, the XP-60B was modified to take the R-2800-10 engine with turbocharger driving
9996-474: The U.S. Army changed to that of solely being the training and logistics elements of the then-new United States Army Air Forces , which embraced the formerly-named General Headquarters Air Force under the new Air Force Combat Command organization for front-line combat operations; this new element, along with the Air Corps, comprised the USAAF. The Air Corps ceased to have an administrative structure after 9 March 1942, but as "the permanent statutory organization of
10143-418: The USAAF recommended that Curtiss concentrate on license production of Republic P-47 Thunderbolts . The P-60 project was not stopped but a decision was taken to build experimental aircraft on the XP-60 but with different engines. The new order issued on 2 January 1942 specified one XP-60A (Model 95A) with the Allison V-1710-75 engine and a General Electric B-14 turbo-supercharger, one XP-60B (Model 95B) with
10290-446: The War Department, 14 four-engine planes were delivered to the air force up to the outbreak of World War II in September 1939." A major step toward creation of a separate air force occurred on 1 March 1935 with the activation of a centralized, air force-level command headed by an aviator answering directly to the Army Chief of Staff . Called the General Headquarters Air Force , the organization had existed in Army planning since 1924 as
10437-409: The XP-60C. In the meantime, Curtiss installed a Packard V-1650-3 (equivalent of the Merlin 61) in the original XP-60 with a four bladed propeller and the larger XP-60A vertical stabilizer; this aircraft was redesignated XP-60D . The XP-60A first flew on 1 November 1942. While official interest in the type was waning (with the emergence of newer designs), the promise of improved performance from use of
10584-472: The XP-60E was flown to Eglin Field for official trials, where USAAF pilots found that it did not compare favorably to contemporary aircraft designs. However, when Curtiss suggested abandoning future work on the P-60 series, the USAAF insisted on completion of at least one of the two aircraft already in production. Somewhat confusingly, the first production aircraft was still designated YP-60A-1-CU, although this
10731-440: The acquisition of obsolete aircraft as first-line equipment, stifled design development in the private sector of better types, retarded the development of radar and ordnance, and handicapped training, doctrine, and offensive organization by reneging on commitments to acquire the B-17. "From October 1935 until 30 June 1939, the Air Corps requested 206 B-17's and 11 B-15's. Yet because of cancellations and reductions of these requests by
10878-501: The activation of GHQ Air Force in December 1934. GHQ Air Force took control of all combat air units in the United States from the jurisdiction of corps area commanders, where it had resided since 1920, and organized them operationally into a strike force of three wings. The GHQ Air Force remained small in comparison to European air forces. On its first day of existence, the command consisted of 60 bombers, 42 attack aircraft, 146 pursuits, and 24 transports, amounting to 40% of strength in
11025-474: The air arm, and the principal component of the Army Air Forces," the overwhelming majority of personnel assigned to the AAF were members of the Air Corps. Public Law 69-446, 2 July 1926 The U.S. Army Air Service had a brief but turbulent history. Created during World War I by executive order of President Woodrow Wilson after America entered the war in April 1917 as the increasing use of airplanes and
11172-399: 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
11319-428: 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
11466-405: 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
11613-410: 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
11760-651: The argument for an independent air force. Strategic or long-range bombardment was intended to destroy an enemy's industry and war-making potential, and only an independent service would have a free hand to do so. But despite what it perceived as "obstruction" from the War Department, much of which was attributable to a shortage of funds, the Air Corps made great strides during the 1930s. A doctrine emerged that stressed precision bombing of industrial targets by heavily armed long-range aircraft. This doctrine resulted because of several factors. The Air Corps Tactical School moved in July 1931 to Maxwell Field , Alabama , where it taught
11907-407: 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
12054-440: 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
12201-403: 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)
12348-403: The blame on him for the Air Corps' failures, he was investigated by a congressional subcommittee alleging corruption in aircraft procurement. The matter resulted in an impasse between committee chairman William N. Rogers and Secretary of War George Dern before being sent to the Army's Inspector General, who ruled largely in favor of Foulois. Rogers continued to severely criticize Foulois through
12495-466: The choice to two of the three assistant chiefs, Henry Conger Pratt and Oscar Westover . Pratt appeared to have the superior credentials, but he had been in charge of aircraft procurement during the Foulois years and was looked upon warily by Dern as possibly being another Mitchell or Foulois. Westover was chosen because he was the philosophical opposite of the two insurgent airmen in all respects, being
12642-525: The company as Model 90 - designated XP-60 . A Packard-built V-1650-1 (equivalent to the Merlin Mk XX) as being used on the Curtis XP-40F was to be used. The airframe design for the XP-60 was modified for the different engine, and the main landing gear was changed from the rearward-retracting P-40 design to a new inward retracting version, as used on the XP-46, which allowed a wider wheelbase and
12789-533: The concept of air power and an autonomous air force in the years between the world wars , its primary purpose by Army policy remained support of ground forces rather than independent operations. On 1 March 1935, still struggling with the issue of a separate air arm, the Army activated the General Headquarters Air Force for centralized control of aviation combat units within the continental United States, separate from but coordinate with
12936-670: The concept one step further in March 1930 by recommending that the types instead be light and heavy , the latter capable of long range carrying a heavy bomb load that could also be used during daylight. The Air Corps in January 1931 "got its foot in the door" for developing a mission for which only it would have capability, while at the same time creating a need for technological advancement of its equipment. Chief of Naval Operations Admiral William V. Pratt wanted approval of his proposition that all naval aviation including land-based aircraft
13083-400: The continuing movement within the Air Corps for independence, cooperated to resist it. On 11 September 1935, the Joint Board, at the behest of the Navy and with the concurrence of MacArthur, issued a new "Joint Action Statement" that once again asserted the limited role of the Air Corps as an auxiliary to the "mobile Army" in all its missions, including coastal defense. The edict was issued with
13230-594: The designation C-33 to equip the first permanent transport unit, the 10th Transport Group, activated in June 1937 at Patterson Field in Ohio . In 1939 the Air Corps recognized that it might soon require large numbers of modern air transports for use in war and purchased 35 DC-2/ DC-3 hybrids, designated the C-39. After the fall of France, the Air Corps in September 1940 ordered 200 untried and unproven Curtiss C-46 Commandos from Curtiss-Wright and 545 Douglas C-47 Skytrains ,
13377-532: The development of longer-ranged bombers, Project A for a bomber with a ferry range of 5,000 miles (8,000 km), and Project D, for one of a range of up to 10,000 miles (16,000 km). In June 1936 the Air Corps requested 11 B-15s and 50 B-17s for reinforcing hemispheric defense forces in Hawaii, Alaska, and Panama. The request was rejected on the basis that there were no strategic requirements for aircraft of such capabilities. The Army and Navy, both cognizant of
13524-424: The development of the Air Corps in the short run, and had hardened the opposition of an already antagonistic General Staff. But through their mistakes and repeated rebuffs, the airmen had learned what they were lacking: proof for the argument that the Air Corps could perform a unique mission—strategic bombardment—and the real threat of another world war would soon reverse their fortunes. In March 1928, commenting on
13671-467: 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
13818-575: 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
13965-431: 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
14112-673: The forerunner of the more than 10,000 C-47s and related variants that served in World War II. Even with the doctrine of strategic bombardment as its priority, the Air Corps belatedly sought to modernize its tactical combat force under GHQ Air Force, bringing into service the Northrop A-17 and Douglas B-18 Bolo in 1936, the Seversky P-35 in 1937, and the Curtiss P-36 in 1938. All of these aircraft were obsolete by
14259-463: 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)
14406-574: 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
14553-503: The geopolitical realities of coming war. In August 1939 the Army's research and development program for 1941 was modified with the addition of nearly five million dollars to buy five long-range bombers for experimental purposes, resulting on 10 November 1939 in the request by Arnold of the developmental program that would create the Boeing B-29 Superfortress , which was approved on 2 December. Between 1930 and 1938
14700-414: 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
14847-419: The intent of again shoving an upstart Air Corps back into its place. However, the bomber advocates interpreted its language differently, concluding that the Air Corps could conduct long-range reconnaissance, attack approaching fleets, reinforce distant bases, and attack enemy air bases, all in furthering its mission to prevent an air attack on America. A month later (15 October 1935), the General Staff released
14994-539: The lack of survivability in combat of his unit's Keystone LB-7 and Martin NBS-1 bombers, Lt. Col. Hugh J. Knerr , commander of the 2nd Bombardment Group at Langley Field , Virginia , recommended that the Air Corps adopt two types of all-metal monoplane bombers, a short-range day bomber and a long-range night bomber. Instructors at the Air Corps Tactical School (ACTS), also then at Langley, took
15141-400: 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
15288-560: The lines of the Marine Corps within the Navy Department, but this was rejected; only the cosmetic name change was accepted. The legislation changed the name of the Air Service to the Air Corps, (in the words of one analyst) "thereby strengthening the conception of military aviation as an offensive, striking arm rather than an auxiliary service." The Air Corps Act (44 Stat. 780) became law on 2 July 1926. In accordance with
15435-450: The mantle of the radical airmen, and Westover soon found himself on "the wrong side of history" as far as the future of the Air Corps was concerned. Lines of authority were also blurred as GHQ Air Force controlled only combat flying units within the continental United States. The Air Corps was responsible for training, aircraft development, doctrine, and supply, while the ground forces corps area commanders still controlled installations and
15582-597: The military uses of aviation were readily apparent as the war continued to its climax, the U.S. Army Air Service gained permanent legislative authority in 1920 as a combatant arm of the line of the United States Army . There followed a six-year struggle between adherents of airpower and the supporters of the traditional military services about the value of an independent Air Force, intensified by struggles for funds caused by skimpy budgets, as much an impetus for independence as any other factor. The Lassiter Board,
15729-408: The mission of the Air Corps in coastal defense was only for supporting the Navy if called upon to do so, while simultaneously authorizing for the Navy the long-range shore-based coastal patrol mission denied the Air Corps. Westover, who stridently opposed cancellation of the Woodring program, was killed in an air crash on 21 September 1938 and was succeeded by Arnold. The Air Corps tested and employed
15876-538: The most numerous of the attack planes that fulfilled the observation/close support role designated by the General Staff as the primary mission of the Air Corps. Transport aircraft used during the first ten years of the Air Corps were of largely trimotor design, such as the Atlantic-Fokker C-2 and the Ford C-3 , and were procured in such small numbers (66 total) that they were doled out one airplane to
16023-410: The next decade: an all-metal low wing monoplane, closed cockpits, rotating gun turrets, retractable landing gear, internal bomb bay, high-lift devices and full engine cowlings. The B-10 proved to be so superior that as its 14 operational test models were delivered in 1934 they were fed into the Air Corps mail operation, and despite some glitches caused by pilot unfamiliarity with the innovations, were
16170-636: The opening chapter of the Air Corps manual be a doctrinal statement developed by the G-3 that "left little doubt" that the General Staff's intention was "to develop and employ aviation in support of ground forces." The Air Corps Board, on the orders of Arnold, developed a secret study for "defense of the Monroe Doctrine " that recommended development of long-range, high altitude, high-speed aircraft for bombardment and reconnaissance to accomplish that defense. The War Department, seeking to stifle procurement of
16317-432: 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
16464-429: The personnel manning them. An example of the difficulties this arrangement imposed on commanders was that while the commander of GHQ Air Force was responsible for the discipline of his command, he had no court martial authority over his personnel, which was retained by the corps area commander. Base commanders of Air Corps installations reported to as many as four different higher echelons. The issue of control of bases
16611-417: 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
16758-470: The political impact of the pending court-martial of Billy Mitchell (and to preempt the findings of the Lampert Committee). It declared that no threat of air attack was likely to exist to the United States, rejected the idea of a department of defense and a separate department of air, and recommended minor reforms that included renaming the air service to allow it "more prestige". In early 1926
16905-459: The primary defenses against interception. In both 1932 and 1933, large-scale maneuvers found fighters unable to climb to altitude quickly enough to intercept attacking B-9 and B-10 prototypes, a failure so complete that Westover, following the 1933 maneuvers, actually proposed elimination of pursuits altogether. 1933 was a pivotal year in the advancement of aviation technology in which the all-metal airplane came of age, "practically overnight" in
17052-471: The probability of war became apparent. Instead, the Air Corps inventory actually declined to 855 total aircraft in 1936, a year after the creation of GHQ Air Force, which by itself was recommended to have a strength of 980. The most serious fallout from the Air Mail fiasco was the retirement under fire of Major General Benjamin Foulois as Chief of Air Corps. Soon after the Roosevelt administration placed
17199-421: The program of the Lassiter Board already in effect, but Chief of Staff Gen. John Hines rejected the recommendation in favor of a plan drawn up by ground force Brig. Gen. Hugh Drum that proposed 52 squadrons. The act authorized expansion to 1,800 airplanes, 1,650 officers, and 15,000 enlisted men, to be reached in regular increments over a five-year period. None of the goals was reached by July 1932. Neither of
17346-561: 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
17493-525: The recommendations of the Baker Board , established in the wake of the Air Mail scandal, was that the proposals of the Drum Board be adopted: an increase in strength to 2,320 aircraft and establishment of GHQ Air Force as a permanent peacetime tactical organization, both to ameliorate the pressures for a separate air force and to exploit emerging capabilities in airpower. In the absence of a general headquarters (i.e. peacetime), GHQ Air Force would report to
17640-517: The recommendations of the Baker Board inadequate for American defense and requested approval of a "minimum 3,000-plane increase" for the Air Corps. On 3 April 1939, Congress allocated the $ 300 million requested by Roosevelt for expansion of the Air Corps, half of which was dedicated to purchasing planes to raise the inventory from 2,500 to 5,500 airplanes, and the other half for new personnel, training facilities, and bases. Orders for B-17s, which had been held in abeyance since June 1938, resumed in
17787-541: The relatively modest increases in airplanes or officers was accomplished until 1938 because adequate funds were never appropriated and the coming of the Great Depression forced reductions in pay and modernization across the board in the Army. Organizationally the Air Corps doubled from seven to fifteen groups , but the expansion was meaningless because all were seriously understrength in aircraft and pilots. ( Origin of first seven groups shown here ) As units of
17934-411: 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
18081-405: The same time, the General Staff ordered studies from all the service branches to develop drafts for the coming field manuals. The Air Corps Board, a function of the ACTS, submitted a draft in September 1938 that included descriptions of independent air operations, strategic air attacks, and air action against naval forces, all of which the General Staff rejected in March 1939. Instead, it ordered that
18228-410: 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
18375-477: The school's Pursuit Section, found their influence waning because of repeated performance failures of pursuit aviation. Finally, the doctrine represented the Air Corps' attempt to develop autonomy from the General Staff, which enforced subordination of the air arm by limiting it to support of ground forces and defense of United States territory. New bomber types under development clearly outperformed new pursuit types, particularly in speed and altitude, then considered
18522-523: The sphere of influence of the Ground Forces" (strategic bombardment), but it did not attach any importance to prioritization of targets, weakening its effectiveness as doctrine. The Air Corps in general assented to the changes, as it did to other compromises of the period, as acceptable for the moment. TR 440-15 remained the doctrinal position of the Air Corps until it was superseded by the first Air Corps Field Manual, FM 1–5 Employment of Aviation of
18669-444: The summer of 1935, threatening future Air Corps appropriations, and despite public support by Dern for the embattled chief, the administration was close to firing Foulois for his perceived attitude as a radical airman and his public criticisms of the administration during the controversy. He retired in December 1935 for the good of the service. The Roosevelt administration began a search for his replacement in September 1935, narrowing
18816-419: The summer of 1939 with incremental deliveries of 39 B-17Bs in 1939–40, 18 B-17Cs in 1940, and 42 B-17Ds in the first quarter of 1941. The first large order for heavy bomber production, 512 combat-capable B-17Es , was placed in July 1940. Propeller (aircraft) In aeronautics , an aircraft propeller , also called an airscrew , converts rotary motion from an engine or other power source into
18963-556: The time they came into service, and the outbreak of war in Europe spurred development of more capable types. By October 1940, over a year before the United States was drawn into the war, every piston-driven single-seat fighter eventually used by the USAAF during World War II was in flight test except the P-47. However, the press of the enormous tasks confronting the Air Corps and the primacy of strategic bombing doctrine meant that development of
19110-530: 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 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
19257-427: The undersurface of the lower wings. Tail rudders were painted with a vertical dark blue band at the rudder hinge and 13 alternating red-and-white horizontal stripes trailing. The painting of fuselages olive drab was changed to blue in the early 1930s, and this motif continued until late 1937, when all new aircraft (now all-metal) were left unpainted except for national markings. Most pursuit fighters before 1935 were of
19404-445: 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
19551-482: The words of one historian, because of the availability of the first practical variable-pitch propeller . Coupled with "best weight" design of airframes, the controllable pitch propeller resulted in an immediate doubling of speeds and operating ranges without decreasing aircraft weights or increasing engine horsepower, exemplified by the civil Douglas DC-1 transport and the military Martin B-10 bomber. The B-10 featured innovations that became standard internationally for
19698-482: Was ameliorated in 1936 when GHQAF bases were exempted from corps area authority on recommendation of the Inspector General's Department, but in November 1940 it was restored again to Corps Area control when Army General Headquarters was activated. In January 1936, the Air Corps contracted with Boeing for thirteen Y1B-17 Flying Fortress prototypes, enough to equip one squadron for operational testing and
19845-500: Was by definition tied to carrier-based fleet operations. Pratt reached an agreement with new Army Chief of Staff Douglas MacArthur that the Air Corps would assume responsibility for coastal defense (traditionally a primary function of the Army but a secondary, wartime function of the Navy) beyond the range of the Army's Coast Artillery guns, ending the Navy's apparent duplication of effort in coastal air operations. The agreement, intended as
19992-535: Was considered in its place. This was expected to deliver 394 mph at 25,000 ft. Consequently, on 31 October 1941, a contract for 1,950 P-60A fighters using the Allison engine was awarded with deliveries expected in September 1942. Flight tests of the XP-60 prototype did not progress smoothly. In addition to landing gear problems, expected top speed was not being met due to shortcomings in the laminar-flow wing surface finish, relatively high radiator drag (compared to
20139-616: 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
20286-476: Was found that due to its lighter weight, the engine installation had to be moved 10 in (250 mm) forward compared to the XP-60C. In April 1943, the US Army Air Forces decided to conduct an evaluation of the various fighter aircraft in development and use, in order to eliminate the least desirable models. With four days notice Curtiss was requested to have the XP-60E participate. As the XP-60E
20433-425: Was later changed to YP-60E , to conform with the naming of previous prototypes. The YP-60E was powered by a 2,100 hp (1,566 kW) R-2800-18 engine. It also featured a cut-down rear fuselage and bubble canopy for improved visibility. It first flew on 13 July 1944 and was subsequently delivered to Wright Field . However, as the government's development contract had already been cancelled (June 1943), there
20580-506: Was made towards vertical flight. His notes suggested that he built small flying models, but there were no indications for any provision to stop 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
20727-624: Was no budget for further modifications, let alone a guarantee of a final purchase order. Consequently, the only production YP-60E completed was scrapped, on 22 December 1944. The XP-60E survived to be sold as an entry for the 1947 National Air Races , but crashed during a qualifying flight before the competition was held. Data from Curtiss Aircraft 1907–1947 General characteristics Performance Armament Related development Aircraft of comparable role, configuration, and era Related lists United States Army Air Corps The United States Army Air Corps ( USAAC )
20874-482: Was not available, the company hurriedly prepared the XP-60C (at the time being repaired) for the evaluation at Patterson Field . The XP-60C performed poorly due to flaking wing finish preventing laminar flow and the engine delivering less power resulting in reduction of the production run of 500 aircraft to 20 YP-60A then to just two aircraft. On 6 May 1943, the XP-60D crashed during a dive demonstration. In January 1944,
21021-560: Was not overcome until the necessity of expanding the force occurred with the onset of World War II. The commanding general of GHQ Air Force, Maj. Gen. Frank M. Andrews , clashed philosophically with Westover over the direction in which the air arm was heading, adding to the difficulties, with Andrews in favor of autonomy and Westover not only espousing subordination to the Army chain of command but aggressively enforcing his prohibitions of any commentary opposed to current policy. Andrews, by virtue of being out from Westover's control, had picked up
21168-447: 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
21315-405: Was renamed from the earlier United States Army Air Service on 2 July 1926, and was part of the larger United States Army . The Air Corps became the United States Army Air Forces (USAAF) on 20 June 1941, giving it greater autonomy from the Army's middle-level command structure. During World War II , although not an administrative echelon, the Air Corps (AC) remained as one of the combat arms of
21462-440: Was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I , as early aviation became an increasingly important part of modern warfare, a philosophical rift developed between more traditional ground-based army personnel and those who felt that aircraft were being underutilized and that air operations were being stifled for political reasons unrelated to their effectiveness. The USAAC
21609-480: Was useful mainly as "long range artillery." Air Corps officers in the G-3 Department of the General Staff pointed out that Jones' conclusions were inconsistent with the revised TR 440-15, but their views were dismissed by Deputy Chief of Staff Maj. Gen. Stanley Embick with the comment: "No doctrine is sacrosanct, and of all military doctrines, that of the Air Corps should be the last to be so regarded." At
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