The Boeing XP-7 was a prototype United States biplane fighter of the 1920s. The XP-7 started life as the last Boeing Model 15, serial 28-41, it was adapted to mount the 600 hp Curtiss V-1570 Conqueror engine. Labelled by Boeing as their Model 93, the XP-7's nose was shorter and deeper than that of the standard PW-9, the craft was 75 pounds lighter overall, it first flew in September 1928 and did well, with a 17 mph speed increase over the PW-9. However, despite a proposal to build an additional four P-7s, the design was at the limits of its capabilities and somewhat outdated by the time of its first flight. At the end of testing, the Conqueror engine was removed and the aircraft converted back into a PW-9D. United StatesUnited States Army Air Corps Data from General characteristics Crew: 1 Length: 24 ft 0 in Wingspan: 32 ft 0 in Height: 9 ft 0 in Wing area: 252 ft2 Empty weight: 2,358 lb Gross weight: 3,260 lb Powerplant: 1 × Curtiss V-1570-1, 600 hp Performance Maximum speed: 167.5 mph Cruise speed: 134 mph Range: 250 miles Service ceiling: 22,300 ft Rate of climb: 1408 ft/min Armament 1x.50in machine gun 1x.30in machine gun 125lb bombs Related lists List of military aircraft of the United States List of fighter aircraft BibliographyAngelucci, Enzo.
The American Fighter from 1917 to the present. New York: Orion Books. Lloyd S. Jones, U. S. Fighters pp. 32–33 ISBN 0-8168-9200-8
The Boeing XP-9 was the first monoplane fighter aircraft produced by the United States aircraft manufacturing company Boeing. It incorporated sophisticated structural refinements that were influential in Boeing designs; the sole prototype exhibited unsatisfactory characteristics with its lack of pilot visibility directly leading to its cancellation. The XP-9 was designed in 1928 to meet the requirements of a US Army request for a monoplane fighter, its primary contribution to aircraft design was its semi-monocoque construction, which would become a standard for future aircraft. Boeing employed the structural features of the XP-9 into their contemporary P-12 biplane fighter when the P-12E variant incorporated a semi-monocoque metal fuselage structure similar to that of the XP-9; the undercarriage arrangement of the P-12C had been first tried out on the XP-9 and transferred into the production model. The prototype XP-9, marked A 028-386, was first flown on 18 November 1930, it had impressive stats on the specification sheet, but it became apparent that its large wing, placed atop the fuselage directly in front of the pilot, obstructed downward visibility so badly that simple landing maneuvers were hazardous.
Test pilots at the Army Test Centre at Wright Field found that the XP-9's inherent instability was so severe that immediate modifications were requested to increase the size of the vertical tail. An enlarged vertical tail surface with smooth metal skinning was introduced, but failed to effect any significant improvement, this revised XP-9 was grounded for instructional airframe use in August 1931, after only 15 hours of test flying. Model 96, XP-9 one built Y1P-9 option for five service test aircraft under the P-12D contract, option was not taken up United StatesUnited States Army Data from "The Complete Encyclopedia of World Aircraft" General characteristics Crew: 1 Length: 25 ft 1.75 in Wingspan: 36 ft 6 in Height: 7 ft 10.25 in Wing area: 210 ft2 Empty weight: 2,669 lb Max. Takeoff weight: 3,623 lb Powerplant: × 1 Curtiss SV-1570-15 Conqueror, 600 hp eachPerformance Maximum speed: 185 knots Cruise speed: 156.4 knots Range: 369 nautical miles Service ceiling: 26,800 ft Rate of climb: 1,560 ft/min Armament 2 machineguns, one.30 and one.50, 125 lbs bombs.
Related lists List of military aircraft of the United States List of fighter aircraft United States Air Force Museum: Boeing XP-9
The Seversky XP-41 was a fighter aircraft built in the United States in 1939. A single prototype was modified from the last production Seversky P-35 by adding a new streamlined canopy, a Pratt & Whitney R-1830-19 engine with a two-speed supercharger, revised landing gear; the XP-41 first flew in March 1939. The aircraft was developed in parallel with the P-43 Lancer, work was stopped when the USAAC showed a preference for the latter. Data fromGeneral characteristics Crew: One Length: 27 ft 0 in Wingspan: 36 ft 0 in Height: 12 ft 6 in Wing area: 219.5 ft² Empty weight: 5,390 lb Loaded weight: 6,600 lb Max. Takeoff weight: 7,200 lb Powerplant: 1 × Pratt & Whitney R-1830-19 radial engine with a two-speed supercharger, 1,200 hp Performance Maximum speed: 323 mph Cruise speed: 292 mph Range: 730 mi Service ceiling: 31,500 ft Wing loading: 30.1 lb/ft² Power/mass: 0.18 hp/lb Armament Guns: 1 × 0.50 in machine gun and 1 × 0.30 in machine gun Related development Republic P-43 Lancer Republic P-47 Thunderbolt Seversky P-35 Related lists List of fighter aircraft List of military aircraft of the United States Media related to Seversky XP-41 at Wikimedia Commons
Curtiss P-40 Warhawk
The Curtiss P-40 Warhawk is an American single-engined, single-seat, all-metal fighter and ground-attack aircraft that first flew in 1938. The P-40 design was a modification of the previous Curtiss P-36 Hawk which reduced development time and enabled a rapid entry into production and operational service; the Warhawk was used by most Allied powers during World War II, remained in frontline service until the end of the war. It was the third most-produced American fighter of World War II, after the P-51 and P-47. P-40 Warhawk was the name the United States Army Air Corps and after June 1941, USAAF-adopted name for all models, making it the official name in the U. S. for all P-40s. The British Commonwealth and Soviet air forces used the name Tomahawk for models equivalent to the P-40B and P-40C, the name Kittyhawk for models equivalent to the P-40D and all variants. P-40s first saw combat with the British Commonwealth squadrons of the Desert Air Force in the Middle East and North African campaigns, during June 1941.
No. 112 Squadron Royal Air Force, was among the first to operate Tomahawks in North Africa and the unit was the first Allied military aviation unit to feature the "shark mouth" logo, copying similar markings on some Luftwaffe Messerschmitt Bf 110 twin-engine fighters. The P-40's lack of a two-speed supercharger made it inferior to Luftwaffe fighters such as the Messerschmitt Bf 109 or the Focke-Wulf Fw 190 in high-altitude combat and it was used in operations in Northwest Europe. However, between 1941 and 1944, the P-40 played a critical role with Allied air forces in three major theaters: North Africa, the Southwest Pacific, China, it had a significant role in the Middle East, Southeast Asia, Eastern Europe and Italy. The P-40's performance at high altitudes was not as important in those theaters, where it served as an air superiority fighter, bomber escort and fighter-bomber. Although it gained a postwar reputation as a mediocre design, suitable only for close air support, more recent research including scrutiny of the records of individual Allied squadrons indicates that this was not the case: the P-40 performed well as an air superiority fighter, at times suffering severe losses, but inflicting a heavy toll on enemy aircraft.
Based on war-time victory claims, over 200 Allied fighter pilots from 7 different nations became aces flying the P-40, with at least 20 double aces in the North Africa, China-Burma-India and Russian Front theaters. The P-40 offered the additional advantage of low cost, which kept it in production as a ground-attack aircraft long after it was obsolete as a fighter. On 14 October 1938, Curtiss test pilot Edward Elliott flew the prototype XP-40 on its first flight in Buffalo; the XP-40 was the 10th production Curtiss P-36 Hawk, with its Pratt & Whitney R-1830 Twin Wasp 14-cylinder air-cooled radial engine replaced at the direction of Chief Engineer Don R. Berlin by a liquid-cooled, supercharged Allison V-1710 V-12 engine; the first prototype placed the glycol coolant radiator in an underbelly position on the fighter, just aft of the wing's trailing edge. USAAC Fighter Projects Officer Lieutenant Benjamin S. Kelsey flew this prototype some 300 miles in 57 minutes 315 miles per hour. Hiding his disappointment, he told reporters that future versions would go 100 miles per hour faster.
Kelsey was interested in the Allison engine because it was sturdy and dependable, it had a smooth, predictable power curve. The V-12 engine offered as much power as a radial engine but had a smaller frontal area and allowed a more streamlined cowl than an aircraft with a radial engine, promising a theoretical 5% increase in top speed. Curtiss engineers worked to improve the XP-40's speed by moving the radiator forward in steps. Seeing little gain, Kelsey ordered the aircraft to be evaluated in a NACA wind tunnel to identify solutions for better aerodynamic qualities. From 28 March to 11 April 1939, the prototype was studied by NACA. Based on the data obtained, Curtiss moved the glycol coolant radiator forward to the chin. Other improvements to the landing gear doors and the exhaust manifold combined to give performance, satisfactory to the USAAC. Without beneficial tail winds, Kelsey flew the XP-40 from Wright Field back to Curtiss's plant in Buffalo at an average speed of 354 mph. Further tests in December 1939 proved.
An unusual production feature was a special truck rig to speed delivery at the main Curtiss plant in Buffalo, New York. The rig moved the newly built P-40s in two main components, the main wing and the fuselage, the eight miles from the plant to the airport where the two units were mated for flight and delivery; the P-40 was conceived as a pursuit aircraft and was agile at low and medium altitudes but suffered from a lack of power at higher altitudes. At medium and high speeds it was one of the tightest-turning early monoplane designs of the war, it could out turn most opponents it faced in North Africa and the Russian Front. In the Pacific Theater it was out-turned at lower speeds by the lightweight fighters A6M Zero and Nakajima Ki-43 "Oscar" which lacked the P-40's structural strength for high-speed hard turns; the American Volunteer Group Commander Claire Chennault advised against prolonged dog-fighting with the Japanese fighters due to speed reduction favouring the Japanese. Allison's V-1710 engines produced 1,040 hp at sea level and 14,000 ft
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, is called a "star engine" in some languages; the radial configuration was used for aircraft engines before gas turbine engines became predominant. Since the axes of the cylinders are coplanar, the connecting rods cannot all be directly attached to the crankshaft unless mechanically complex forked connecting rods are used, none of which have been successful. Instead, the pistons are connected to the crankshaft with a master-and-articulating-rod assembly. One piston, the uppermost one in the animation, has a master rod with a direct attachment to the crankshaft; the remaining pistons pin their connecting rods' attachments to rings around the edge of the master rod. Extra "rows" of radial cylinders can be added in order to increase the capacity of the engine without adding to its diameter.
Four-stroke radials have an odd number of cylinders per row, so that a consistent every-other-piston firing order can be maintained, providing smooth operation. For example, on a five-cylinder engine the firing order is 1, 3, 5, 2, 4, back to cylinder 1. Moreover, this always leaves a one-piston gap between the piston on its combustion stroke and the piston on compression; the active stroke directly helps compress the next cylinder to fire. If an number of cylinders were used, an timed firing cycle would not be feasible; the prototype radial Zoche aero-diesels have an number of cylinders, either four or eight. The radial engine uses fewer cam lobes than other types; as with most four-strokes, the crankshaft takes two revolutions to complete the four strokes of each piston. The camshaft ring is geared to spin slower and in the opposite direction to the crankshaft; the cam lobes exhaust. For example, four cam lobes serve all five cylinders, whereas 10 would be required for a typical inline engine with the same number of cylinders and valves.
Most radial engines use overhead poppet valves driven by pushrods and lifters on a cam plate, concentric with the crankshaft, with a few smaller radials, like the Kinner B-5 and Russian Shvetsov M-11, using individual camshafts within the crankcase for each cylinder. A few engines use sleeve valves such as the 14-cylinder Bristol Hercules and the 18-cylinder Bristol Centaurus, which are quieter and smoother running but require much tighter manufacturing tolerances. C. M. Manly constructed a water-cooled five-cylinder radial engine in 1901, a conversion of one of Stephen Balzer's rotary engines, for Langley's Aerodrome aircraft. Manly's engine produced 52 hp at 950 rpm. In 1903–1904 Jacob Ellehammer used his experience constructing motorcycles to build the world's first air-cooled radial engine, a three-cylinder engine which he used as the basis for a more powerful five-cylinder model in 1907; this was made a number of short free-flight hops. Another early radial engine was the three-cylinder Anzani built as a W3 "fan" configuration, one of which powered Louis Blériot's Blériot XI across the English Channel.
Before 1914, Alessandro Anzani had developed radial engines ranging from 3 cylinders — early enough to have been used on a few French-built examples of the famous Blériot XI from the original Blériot factory — to a massive 20-cylinder engine of 200 hp, with its cylinders arranged in four rows of five cylinders apiece. Most radial engines are air-cooled, but one of the most successful of the early radial engines was the Salmson 9Z series of nine-cylinder water-cooled radial engines that were produced in large numbers during the First World War. Georges Canton and Pierre Unné patented the original engine design in 1909, offering it to the Salmson company. From 1909 to 1919 the radial engine was overshadowed by its close relative, the rotary engine, which differed from the so-called "stationary" radial in that the crankcase and cylinders revolved with the propeller, it was similar in concept to the radial, the main difference being that the propeller was bolted to the engine, the crankshaft to the airframe.
The problem of the cooling of the cylinders, a major factor with the early "stationary" radials, was alleviated by the engine generating its own cooling airflow. In World War I many French and other Allied aircraft flew with Gnome, Le Rhône, Bentley rotary engines, the ultimate examples of which reached 250 hp although none of those over 160 hp were successful. By 1917 rotary engine development was lagging behind new inline and V-type engines, which by 1918 were producing as much as 400 hp, were powering all of the new French and British combat aircraft. Most German aircraft of the time used water-cooled inline 6-cylinder engines. Motorenfabrik Oberursel made licensed copies of the Gnome and Le Rhône rotary powerplants, Siemens-Halske built their own designs, including the Siemens-Halske Sh. III eleven-cylinder rotary engine, unusual for the period in being geared through a bevel geartrain in the rear end of the crankcase without the crankshaft being mounted to the aircraft's airframe, so that the engine's internal working components (fully in
The Boeing XP-15 was a prototype monoplane fighter of the United States, the second to be designated a pursuit type, after the Boeing XP-9. This aircraft was a monoplane version of the Boeing P-12, differing in having the lower wing omitted and in having all-metal construction as well as altered ailerons; the XP-15 had a tail wheel. Boeing numbered the craft as its Model 202; the XP-15 first flew in January 1930, when it was discovered that the vertical stabilizer needed to be larger in order to compensate for the single wing. Initial testing showed a top speed to 178 mph, but with enlarged tail surfaces and a Townend cowling, it recorded 190 mph at 8,000 ft; the aircraft performed poorly, with a poor rate of a high landing speed. The USAAC did not order the aircraft for production and on 7 February 1931, the prototype was destroyed when a propeller blade failed and the engine tore loose from its mounts; the Navy was offered the similar Model 205. It first flew in February 1930, it was ordered by the US Navy, but by the time flight testing was complete in 1932, other aircraft were ordered instead.
It was however, the first US designed monoplane to receive a US Navy designation, XF5B-1, following the German designed Wright WP-1 of 1923. United StatesUnited States Army Air Corps United States Navy Data from Angelucci 1987, pp. 81–82. General characteristics Crew: one Length: 21 ft 0 in Wingspan: 30 ft 6 in Height: 9 ft 4.5 in Wing area: 157.3 ft2 Empty weight: 2,052 lb Gross weight: 2,746 lb Powerplant: 1 × Pratt & Whitney SR-1340D, 525 hp Performance Maximum speed: 190.2 mph Cruise speed: 160 mph Range: 420 miles Service ceiling: 27,650 ft Rate of climb: 1,800 ft/min Armament 2 x.30 inch machine guns Related lists List of military aircraft of the United States List of fighter aircraft Notes Bibliography XF5B-1
Boeing P-26 Peashooter
The Boeing P-26 "Peashooter" was the first American all-metal production fighter aircraft and the first pursuit monoplane to enter squadron service with the United States Army Air Corps. Designed and built by Boeing, the prototype first flew in 1932, the type was still in use with the U. S. Army Air Corps as late as 1941 in the Philippines. There are only two surviving Peashooters, but there are three reproductions on exhibit with two more under construction; the project, funded by Boeing, to produce the Boeing Model 248 began in September 1931, with the US Army Air Corps supplying the engines and the instruments. The design, which included an open cockpit, fixed landing gear and externally braced wings, was the last such design procured by the USAAC as a fighter aircraft; the Model 248 had a high landing speed. To remedy this, flaps were fitted to reduce the landing speed; the Army Air Corps ordered three prototypes, designated XP-936, with the first flight on 20 March 1932. The Boeing XP-936 was still tricky to land and it could be rolled onto its back, injuring the pilot.
The prototype's headrest offered little protection in such instances. As a result, production Model 266s had a taller headrest installed to provide some protection. Two fighters were completed as P-26Bs with fuel-injected Whitney R-1340-33 engines; these were followed with carburated R-1340-33s and modified fuel systems. Both the Spanish Air Force and the Republic of China Air Force ordered examples of the Model 281, comparable to the P-26C in 1936; the diminutive "Peashooter", as it was known by service pilots, was faster than previous American combat aircraft. Nonetheless, rapid progress in aviation led to it becoming an anachronism, with wire-braced wings, fixed landing gear and an open cockpit; the stressed-skin cantilever-wing Dewoitine D.500 flew the same year as the P-26 and two years afterwards the Soviet I-16 was flying with retractable landing gear. By 1935, just three years after the P-26, the Curtiss P-36, Messerschmitt Bf 109 and Hawker Hurricane were all flying with enclosed cockpits, retractable landing gear and cantilever wings.
However, the P-26 would remain in service until after the U. S. entered World War II. Deliveries to USAAC pursuit squadrons began in December 1933 with the last production P-26C aircraft coming off the assembly line in 1936. 22 squadrons flew the Peashooter, with peak service being six squadrons, in 1936. P-26s were the frontline fighters of the USAAC until 1938, when Seversky P-35s and Curtiss P-36s began to replace the P-26. A total of twenty P-26s were lost in accidents between 1934 and America's entry into World War II in 1941, but only five before 1940. Air Corps units using the P-26 were the: 1st Pursuit Group, Selfridge Field, Michigan. 8th Pursuit Group, Langley Field, Virginia. Between 1938 and 1940, P-26s were assigned overseas to supplement Seversky P-35s in two defense units based at Wheeler Field, Territory of Hawaii: 18th Pursuit Group 15th Pursuit Group; the 17th PG became the 17th Attack Group in 1935, its P-26s were transferred in 1938 to the 16th Pursuit Group at Albrook Field in the Panama Canal Zone.
These P-26s were transferred in 1940 to the 37th Pursuit Group which flew them until they were replaced by P-40s in May 1941. Some continued service with the 32d Pursuit Group, but only nine P-26s remained operational in Central America at the start of World War II. P-26As were flown by the 3d PS of the 4th Composite Group, based in the Philippines. Between 1937 and 1941, 31 were sold to the fledgling Philippine Army Air Corps; the first Boeing P-26 to experience major combat operation was the Chinese Model 281. On 15 August 1937, eight P-26/281s from the Chinese Nationalist Air Force 3rd Pursuit Group, 17th Squadron, based at Chuyung airfield, engaged eight out of twenty Mitsubishi G3M Nell medium bombers from the Kisarazu Air Group sent to attack Nanking; the Chinese Boeing fighters helped shoot down two of the four Japanese bombers destroyed that day without suffering any losses. Subsequent engagements between the Chinese Peashooter pilots and pilots of the Imperial Japanese Navy flying the Mitsubishi A5M "Claudes" were the first aerial dogfights and kills between all-metal monoplane fighter aircraft.
A single P-26 was in service with the Spanish Republican Air Force during the Spanish Civil War of 1936–1939, but no aerial kills were recorded with this fighter aircraft. It was shot down in 1936. By December 1941, U. S. fighter strength in the Philippines included twenty-eight P-26s, 12 of which were operational with the 6th Pursuit Squadron of the Philippine Army Air Corps. Filipino-flown P-26s claimed one G3M and two or three Mitsubishi A6M2 Zeros before the last of the P-26s were burned by their crews on 24 December 1941. Only nine P-26s remained airworthy. In 1942–43, the Fuerza Aérea de Guatemala acquired seven P-26s ostensibly by the U. S. government smuggling them in as "Boeing PT-26A" trainers to get around restrictions of sales to Latin American countries. The last two P-26s in service were still flying with Guatemala's air force until 1956, when they were replaced with P-51 Mustangs; the P-26's last combat operation was with the Guatemal