The Northrop XP-56 Black Bullet is a experimental Fighter plan American. He knew many problems during his development and thus never in service within the US Air Force entered. It is now exposed to the National Air and Space Museum with Washington DC.
Design
In June 1939, division material of the US Army Air Body began creation from a Schedule of conditions, aiming at providing him a new hunter, whose Invitation to tender would relate to the financial year 1940. This schedule of conditions was cold on September 18th, 1939. This one aimed at the design of a hunter equipped with performances hitherto still not considered, the apparatus was to be able to reach a maximum speed of 850 km/h with: 4500 m of altitude. Thirteen aeronautical manufacturers were chooses to receive the invitation to tender. The schedule of conditions was published on February 20th 1940 under name “ Request for dated R40-C ”.In April, only seven manufacturers had proposed their projects. The winner was Vultee, Northrop was classified third behind Curtiss-Wright. Three prototypes were then ordered under designations XP-54, XP-55 and XP-56.
The project of Northrop indicated N2 in the nomenclature manufacturer was characterized by a fuselage runs what conferred a squat profile to him, a ventral drift and pusher airscrews contrarotating. Keith To wrinkle and its team had conceived five indicated alternatives N2, N-2A, N-2B, N-2C and N-2D. They were different by their motorization and their armament. Another important characteristic, the apparatus was to be built in Magnésium, but this material cannot be riveted as it is the case with the Tôle S in Acier or in Aluminum, Northrop thus engaged an expert in this field, Vladimir Pavlecka. This one developed and patented a technique of Soudage called “Heliarc”.
The launching of the first phase of development was authorized on June 22nd, 1940, it consisted in constituting the calculations file and building models of Soufflerie. In same time, work of phase 2 consistent in the construction of one model to the scale 1:1 for interior installation and of a prototype, began. Initially the studies concentrated on the versions equipped with the X-1800 engine while paying attention so that the assembly of R-2800 remains possible. The Division of the material of US Army Air Body then decided to order a second prototype indicated XP-56A equipped with the R-2800 engine equipped with a Turbocompresseur on two floors and two speeds. This one was to intend for the exploration of the flight envelope, but this type of engine being available more quickly, it was decided that it would be the first to be flown, while model XP-56 would be used for the development of the production aircraft.
Starting from September 9th, the model on the scale 1:5 was tested in the blower California Institute off Technology. These tests being conclusive, the procedure of orders of prototypes was initiated and on September 26th the first prototype was officially ordered, for a delivery in the twelve months. However difficulty were not long in arriving, indeed the War Production Board (Committee of production of war), took the same month the stop of the development of the X-1800 engine so that Pratt & Whitney concentrate on the radial engine . The choice of the engine was made then on on the R2800-BG, of a power of: 2000 ch with: 2700 tr/min, whose development was not finished. This change involved a delay of several months on the development of the prototype, this one being awaited more only for on March 15th, 1942. The Model of installation on the scale 1:1, was controlled as envisaged on July 15th 1941 and did not reveal main issues.
December 15th, a second prototype was ordered for a delivery in June 1942. However their manufacture took delay because of problems which have occurred at Northrop and Pratt & Whitney in particular relating to the development of the power unit. The first prototype was only delivered to the beginning of the year 1943. This one was then dismounted to be transferred onto the base of Muroc Dry Lake in order to carry out rolling tests starting from April 12th. These tests showed that the plane strongly tended to oscillate, this defect was allotted to the brake which were then modified before the plane is not transferred to Rogers Lake to carry out its first vol. Cependant the setting does not have an engine always posing problem, this one was assembled on the plane only in August, making it possible Northrop to carry out improvements.
Finally the XP-56 arrived at Rogers Lake only on September 3rd, and it flew for the first time on September 6th, 1943 with John Myers to the orders. This flight which one could describe as “jump”, lasted in fact only 30 seconds the plane rising only one some two meters height, the second flight the same day did not last to him not more than one minute. The third flight was programmed for on October 8th after the drift was strongly increased and withdrawn trap doors of train. The come day, John Myers decided to carry out some rolling tests and some “jumps”, it noted an instability which it allotted to the brake or the wind of through. To have the heart Net it regained its starting point at high speed of it. Unfortunately are left tire burst causing a yaw followed of two barrel X and half before finding itself on the back. At the time of the accident, the pilot was ejected with his seat of the cockpit and left itself there miraculeusement, victim only of several Fracture S. As for the apparatus, it was definitively out of use.
Following this accident, the second prototype was only little modified, instead of having its entirely re-examined landing gear, the engineers played on the Centrage of the plane by weighing down the nose of the apparatus, they changed the tires and still increased the drift. The second apparatus was sent to Road Lake where it accomplished its first flight with the hands of Harry Crosby, on March 23rd 1944. This flight lasted approximately 10 minutes, during this one the XP-56 reached an altitude of 750 m and a speed of 290 km/h.
After six flights, it became hollowing out that the apparatus could never achieve the goals laid down by the schedule of conditions; its speed maximum of 547 km/h and its altitude of: 6000 m being quite lower than 750 km/h and: 7600 m required, for all to say its performances were even lower than the apparatus already in service the such Republic P-47 Thunderbolt. Moreover, the piloting of the XP-56 proved to be delicate because of big problems of stability and control.
The US Air Force then proposed to pass the apparatus in the blower of NACA to the Ames Research Center and to accomplish trial flights to include/understand the incapacity of the XP-56 to exceed this speed. But this decision was given to later. While waiting for the decision of the US Air Force, the trial flight continued. During its ninth flight, the pilot, Alex Papana, damaged the ventral drift with the landing, which obliged the apparatus to turn over to Northrop to be repaired and modified. This made a tenth flight took place on August 11th, 1944, but no improvement was noted, the performances was always also modest for an excessive fuel consumption. At this time there, the apparatus had carried out only 5:55 min vol.
Finally, the wind tunnel tests were programmed to begin on June 10th 1945, the plane was thus transferred by the road to Moffett where it was stored in a hangar while waiting for its turn. However meanwhile, engineers de Northrop ignored the problem, being under development full of the project of bomber Northrop XB-35.
The XP-56 then took dust in its hangar during one year before being finally yielded to the National Museum off the United States Air Force. It turned over to Northrop between April and November 1946. It joined then the collection of the National Air and Space Museum fine 1947.
With final, nobody never knew why this plane flew so badly.
Description
The XP-56 is the first plane entirely built in Magnésium. It is characterized by three-wheeled train of a footing of 3,83 m and of a way of 3,44 Mr.It is equipped with a Voilure in arrow with 26° on the level of the Leading edge and in dihedral double whose angle with the Emplanture is of 6°. Its lengthening is of 5,91. The wings are positioned with middle height of the fuselage. The intakes air for the engine is in the wing root. Characteristic, this plane does not have a horizontal stabilizer, it precedes already future the hang-gliders of Northrop.
On the level of the power unit, the plane uses an engine Pratt & Whitney R2800-29 Double Wasp developing: 2000 ch au takeoff: 1650 ch with: 6860 m in combat and: 1500 ch with: 6550 m in normal flight. It is a radial engine with air cooling made up of 18 cylinders in double star. It involves two contrarotating propellers of a diameter of 2,95 m for that former and 2,90 m for the posterior one.
Concerning the armament, the XP-56 was designed to be equipped with two guns Hispano-Suiza of 20 mm which can draw 100 Obus each one and of 4 machine-guns Browning m2 of 12,7 mm equipped with 400 balls each one. However it was never assembled.
Alternatives
Versions considered- N2 : version equipped with an engine Pratt & Whitney R-2800-A5G, with two Canon S of 20 mm and two Machine-gun S of 12,7 mm;
- N-2A : version equipped with an engine Pratt & overfed Whitney X-1800-A2G, with two guns of 20 mm and two machine-guns of 12,7 mm;
- N-2B : version equipped with an engine Pratt & turbocompressé Whitney X-1800-A3G, with two guns of 20 mm and two machine-guns of 12,7 mm;
- N-2C : version equipped with an engine Allison V-1710-E9, with two guns of 20 mm and two others of 30 Misters
- N-2D : version equipped with an engine Pratt & Whitney R-1830-C5G, with two guns of 20 mm and two others of 30 Misters
- XP-56 : two apparatuses (n°1: serial number 41-786, n°2 serial number 42-38353) built of which the first will be destroyed during tests in vol.
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