tests began in March 1945 at a test range in Tashkent, with further launches from ground sites and from aircraft of improved versions continuing into the late 1940s. The inaccuracy of the guidance system when compared with new methods such as beam-riding and TV guidance saw development end in the early 1950s. The Soviets also worked on a piloted attack aircraft based on the Argus pulsejet engine of the V-1, which began as a German project, the Junkers EF 126 , in the latter stages of the war. The Soviet development of the ended in 1946 after a crash that killed the test pilot. United States The United States reverse-engineered the V-1 in 1944 from salvaged parts recovered in England during June. By 8 September, the first of thirteen complete prototype Republic-Ford JB-2, was assembled at Republic Aviation. The United States JB-2 was different from the German V-1 in only the smallest of dimensions, with only the forward pulsejet support pylon visibly differing in shape from the original German pilotless ordnance design. The wing span was only wider and the length was extended less than . The difference gave the JB-2 of wing area versus for the V-1. A navalised version, designated KGW-1, was developed to be launched from LSTs as well as escort carriers (CVEs) and long-range 4-engine reconnaissance aircraft. Waterproof carriers for the KGW-1 were developed for launches of the missile from surfaced submarines. Both the USAAF JB-2 and Navy KGW-1 were put into production and were planned to be used in the Allied invasion of Japan (Operation Downfall). However, the surrender of Japan obviated the need for its use. After the end of the war, the JB-2/KGW-1 played a significant role in the development of more advanced surface-to-surface tactical missile systems such as the MGM-1 Matador and later MGM-13 Mace. Operators Surviving examples Australia The Australian War Memorial in Canberra, Australia Belgium The Stampe en Vertongen Museum at Antwerp International Airport has a V-1 on display. Canada The Atlantic Canada Aviation Museum in Halifax, Nova Scotia Denmark The Danish War Museum (Krigsmuseet, formerly Tøjhusmuseet) in Copenhagen France The Grand Bunker Museum in Ouistreham, near Caen and Sword Beach, displays a V-1 flying bomb. Blockhaus d'Éperlecques, near Saint-Omer. Although this was intended as a V-2 launch site the museum on the site has a display devoted to the V-1, including a V-1 cruise missile and an entire launch