Apparently there are only four P-61s in existence world-wide. Besides this P-61C, (43-8330) here at the National Air and Space Museum's Steven F.Udvar-Hazy Center, there is a P-61C (43-8352) at the U.S. Air Force Museum at Wright-Patterson, OH, a P-61A (42-39417) at the Beijing Aeronautics Institute, Beijing, China and a P-61B (42-39445) which has been recovered from a mountain top near Hollandia, Papua New Guinea and is being restored to flying condition by the Mid-Atlantic Air Museum at Reading, PA. The Northrop P-61 Black Widow , named for the American spider, was the first operational U.S. military aircraft designed specifically for night interception of opposing aircraft, and was the first aircraft specifically designed to use radar. The P-61 had a crew of three: pilot, gunner, and radar operator. It was armed with four 20 mm (.79 inch) Hispano M2 forward-firing cannons mounted in the lower fuselage, and four .50 mm (12.7 mm) M2 Browning machine guns mounted in a remote-controlled dorsal gun turret. It was an all-metal, twin-engine, twin-boom design developed during World War II. The first test flight was made on 26 May 1942, with the first production aircraft rolling off the assembly line in October 1943. The last aircraft was retired from government service in 1954. Although not produced in the large numbers of its contemporaries, the Black Widow was effectively operated as a night-fighter by the United States Army Air Forces squadrons in the European Theater, the Pacific Theater, the China Burma India Theater, and the Mediterranean Theater during World War II. It replaced earlier British-designed night-fighter aircraft that had been updated to incorporate radar when it became available. After the war, the P-61 - re-designated the F-61 - served in the United States Air Force as a long-range, all weather, day/night interceptor for Air Defense Command until 1948, and Fifth Air Force until 1950 (Wikipedia and other sources). This picture was taken on 3 June 2015, Sig...