At that time, the US Navy put forward a tender for patrol aircraft to the aviation industry, and the final competition was launched between the joint XP3Y- 1 and Douglas XP3D- 1. These two models have successfully completed the flight test project, reaching all performance indicators, and there are no major defects. Because the performance is equivalent, we started to compete from the price. The joint unit price was 90,000 US dollars (the currency value of that year), which was 20,000 US dollars lower than that of Douglas, and won the contract.
Shortly after the British Air Force received the first batch of PBY in June, 5438+0940, it was named "Katrina" in June, 5438+0 1, named after Katrina Island, a coastal tourist resort in California, USA. When the United States officially named "Katrina" as the nickname of PBY in 194 1, many weapons and equipment between the two countries had already used the same model/nickname. The PBY used by the Royal Canadian Air Force, which is also a Commonwealth, is called "Canso (Canso Strait, Canada)" and the amphibious type is "Canso A". In addition, there is another modification of PBY called Nomad, which is an improved version of PBN- 1 and 1944-45 of PBY-5, and it is produced in Philadelphia Naval Aircraft Factory.
It can be said that without World War II, there would be no success of Katrina. 1939 when the last PBY-4 was delivered, the us navy considered it obsolete. At this time, PBY's successors are already under development, including dual-engine XBPM Mariner, four-engine XBPM2Y coronado and XBPM. After losing the continuous support of the US Navy, the United Company relied on orders from Britain, Canada, Australia, France and the Netherlands to maintain the production of Model 28-5 (export-oriented PBY-5). Since PBY was the only water patrol aircraft that could be mass-produced by the Allied Forces before the war, the US Navy re-ordered 200 PBY-5 aircraft in February 1939, which was the largest single aircraft order of the US Navy since World War I, and also established PBY's unshakable position. PBY was designed by Isaac McLean "Mike" bin Laden, a famous aviation engineer of the United States. In the middle of 1920s, Reuben Fleet, the founder of the joint company, decided to develop the company's business from a successful primary trainer (Army PT and Navy ny trainers produced by the buffalo factory in Buffalo) to the field of heavy multi-engine aircraft to meet the needs of the US Army aviation. In order to enhance its competitiveness, fleet hired Raton in 1927, and formed an alliance with Sikorsky Aviation Engineering Company, an experienced multi-engine aircraft designer, to participate in the bidding for 1927 heavy bomber of Luhang. Raton served as the director of the Army Aircraft Engineering Department in Lightfield, responsible for the research of multi-engine layout. He also personally presided over the development of Boeing's long-range seaplane.
Joint Sikorsky's plan to participate in the bomber competition is a twin-engine biplane, which was developed on the basis of Sikorsky's S-37 for transatlantic flight. Their joint design was named "Guardian", but it failed because its performance was not as good as that of competitor Curtis B-2 "Vulture". But in any case, Raton and his design team have gained valuable experience and will be applied in the near future. The origin of Katrina can be traced back to United XPY- 1, which is a long-range seaplane with a brand-new design concept. It has an all-metal upper monoplane structure and is completely out of the "American" biplane airship layout that followed glenn curtiss since 19 14. The navy first put forward the concept of all-metal single wing structure and submitted the basic design to the aviation industry for bidding to produce prototypes. The joint venture company offered the lowest bid and won a new seaplane contract of $65,438 +0928 on February 28th. Because the aluminum alloy production process at that time was revolutionary, United Airlines had to develop the process and production at the same time, so XPY- 1 "Admiral" was not completed until February 1928, but at this time, it encountered a problem that had never been considered before-the nearby niagara river was frozen, so there was no flight test site for new aircraft! In order to avoid waiting until the next spring to thaw, the navy cooperated with the navy to dismantle the Admiral and transport it to NAS Anacostia by rail for a test flight.
XPY arrived in Castia, Ana on Christmas Day, and immediately began the assembly and testing work under the supervision of Raton. After completing the ground test, Admiral made his first flight in 1929 65438+ 10/0. The pilot is Captain A.W. Gorton, and Mike Raton takes the co-pilot position according to his own practice. United didn't have its own seaplane test pilot at that time, so it borrowed Captain Gordon for its first flight. The test flight shows that XPY's performance meets all requirements, so the navy put forward nine production-oriented tenders in June 1929. Because the joint quotation included the actual engineering cost of the prototype development stage, Glenn L. Martin Company was slightly higher, and as a result, it lost the production contract. Confronted with this setback, United Airlines immediately launched the development of 28 commercial seaplanes based on XPY. This civil mode is called "Commodore", which was adopted by new york Leo Buenos Aires route (the predecessor of Pan Am) and successfully applied to Caribbean and South American routes. Commodore has served in the civil aviation field for many years and has great influence in the commercial aircraft field. 1932, during the delivery of P2Y, the navy launched the design bidding for the next generation of water patrol aircraft, with special emphasis on the great expansion of performance envelope. When cruising at the maximum weight of 1 1.340kg and 16 1 km/h, the range of the new aircraft must reach 4827km, nearly twice that of XPY- 1. United company was invited to accept the design challenge. Mike Raton and his engineering team believe that with the experience gained by P2Y and the record-breaking performance created by P2Y in practical use, they have a great chance of winning.
The result of joint efforts is a newly designed seaplane, which was patented because of its great innovation (the patent number granted to Mike Raton by the US Patent Office was 929 12 on1July 3, 934). After the preliminary examination of this scheme, the Navy signed a contract with Lianhe on 1933 10/28 October to further develop and manufacture a prototype, and awarded the model XP3Y- 1, which was the last step before the birth of PBY.
In this design, the main competitor of United Company is Douglas Company. Douglas enjoys a high reputation in producing multi-engine aircraft. The scheme proposed this time is XP3D- 1. Douglas won the contract for the development and production of a prototype by the navy five months ahead of XP3Y, which took the lead in time. However, Douglas XP3D- 1 is not a brand-new design. It is improved from the amphibious bomber YB- 1 1 designed for the army. Prior to this, YB- 1 1 had gone through two design changes, YO-44 and YOA-5, and had never got a production contract. XP3D- 1 has a single wing layout, and two Pratt & Whitney R- 1830 engines are installed on the bracket above the wing, which is related to Douglas's Dolphin Seaplane and the RD series general transport aircraft of the Coast Guard/Navy. The size of XP3D is slightly smaller than XP3Y, and the climb rate, speed and range are also slightly worse. On February 6th 1935, XP3D made its first flight, which was more than one month ahead of the joint XP3Y.
XP3Y has an exceptionally simple aerodynamic shape. The umbrella-type semi-cantilever wing is connected to the boat-shaped fuselage through struts, and a pair of struts are connected to the wings on both sides of the fuselage to increase strength. The cleverly designed retractable under-wing buoy becomes the wing tip after being put away, which greatly reduces the resistance. The wing is of traditional aluminum alloy structure, the front surface of the rear spar is covered with metal skin, followed by fabric skin, aileron is covered with metal fabric skin, cantilever flat tail is covered with metal skin, elevator and rudder are covered with fabric skin, and all control wings are equipped with adjusting pieces. XP3Y's self-defense weapons include a 12.7mm M2HB Browning machine gun installed in the nose, which is controlled by the bomber, and two stand-up machine guns behind the wing strut with the caliber of 12.7mm or 7.62mm The attack weapons include 45-450kg bombs hanging on the wing pylon, and standard aviation torpedoes can also be mounted through the converter. The window of the nose bombsight is protected by a shutter door, in which the advanced Norden)MK XV bombsight is used. The fuselage is divided into five watertight compartments, and there are watertight doors between the compartments, which improves the sinking resistance. The crew includes bomber/nose gunner, pilot, navigator, radio, random mechanic and two waist gunners. In order to ensure the long-term mission in Qianjin base, the cabin also has sleeping berth, kitchen and food storage facilities. XP3Y, like XP3D, was designated to use the new 825 HP Pratt & Whitney XR- 1830-58 Twin wassens engine to drive Hamilton Standard Company's variable pitch 3-blade constant speed propeller. The engine is installed in the engine compartment and has a complete NACA rectifier shape, and the trailing edge tab is located above the wing. There is an internal fuel tank with a capacity of 6624 liters on the central wing between the two engine compartments.
At the end of 1933, United began to manufacture the prototype in Buffalo factory, which lasted until the beginning of 1935. In order to avoid any delay caused by the icing of the seaplane landing site in niagara river, the company decided to transport XP3Y to NAS Norfolk by rail, and use the naval facilities there for assembly, ground and flight test. XP3Y arrived in Norfolk in early March of 1935, and completed the necessary pre-flight assembly and testing work in mid-March. On March 2 1, joint test pilot Bill whitley made his first flight successfully. The test flight of the factory ended without obvious faults. On March 28th, XP3Y was handed over to the Navy for initial test flight at Anacostia test flight air station, but it encountered a failure during the test flight, but none of them caused the test flight delay. In April, the artillery firing test was carried out, and in May, the plane returned to Norfolk for a choppy water take-off and landing test. The plane was damaged in a landing on May 13, 2003, but it was quickly repaired and continued its test flight.
During the flight test, it has been reported that XP3Y has problems in directional stability and handling, and the manufacturer has made several changes since then, but the effect is not great. Hidden dangers were exposed in the dropping tests in May and June, such as poor directional stability and excessive rudder force, which affected the dropping accuracy. It was found that the rudder area was increased before, but the rudder force was increased at the same time, so the rudder was modified again.
In July, XP3Y returned to Norfolk to continue testing the water. It was seriously damaged in a landing on July 27th. Fortunately, the fuselage waterproof wall and watertight door played a role in preventing the plane from sinking, and XP3Y was towed back to the air station for maintenance. After a record-breaking transition flight from the east coast via the Canal Zone, the water test of XP3Y was completed in June+10/October, 5438.
In the final report of the naval testing department, the production of XP3Y- 1 was evaluated as "acceptable", but the following suggestions were put forward to improve the flight quality and combat capability:
Provide a machine gun station for shooting backwards and downwards.
Improve the waist machine gun station to provide a better view window for the machine gunner.
Increase the bomb load
Modify the rudder and its control system to improve stability and direction control.
Improved nose machine gun station
Anyway, what is significant to the future of PBY is the performance part in the final report of the testing department: the measured data performance requires maximum speed (km/h) 274.82 256 minimum speed (km/h) 93.32 96.54 service upper limit (m) 5669.28 4572 take-off time (seconds) 22 60 empty weight (kg) 5, July 700 5, June 7005. Kloc-0/935, the suggestions of the test department were adopted in this production, including redesigning the rudder, lengthening the fuselage under the rudder, adding a machine gun station to shoot downward in the stern cabin, opening the belly door to shoot backward and downward in flight (soon called "belly machine gun"), equipping the turret with a nose machine gun, and changing the engine to match the production of R- 1830-64.
XP3Y returned to the San Diego factory to implement the above improvements, and the completed aircraft model was changed to XPBY- 1, but the original aviation bureau serial number (BuNo)9459 was retained. The "B" added in the model indicates that this type of aircraft has the ability to carry bombs. Bill whitley, the pilot of the company, made the last demonstration flight at XBPMY-1. On May 2,1,1936, the aircraft was delivered to the navy for military test flight. The military flight test results are satisfactory, and only minor changes are made to the rudder and its control system. In fact, the main problems found in the initial flight test of the prototype are directional stability and control. The improvement of rudder and control system introduced by production has reduced the above problems to an acceptable level, but it has not been completely eradicated. Finally, naval engineers completely solved this problem by completely redesigning the vertical tail and the horizontal tail surface on PBN, PB2B-2 and the final model PBY-6A derived from PBY.