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Unguided air-to-ground missiles definitely increased firepower and efectiveness of Allied tactical air force. Americans seemed to get left behind the British in this case. The first unit of the Ninth Air Force to be armed with 5-inch HVAR rockets (High-Velocity Aircraft Rocket) was the 513th Squadron of the 406th Fighter Group. The target of the premier mission of its Thunderbolts carrying 48 HVARs was the railroad hub in Nevers in eastern France. Explosions destroyed 25 locomotives, a flak tower and the maintenance depot.
Ian Gooderson of University of London in his article Allied Fighter-Bombers versus German Armour in North-West Europe 1944-1945: Myths and Realities summarizes the score of the 513th Squadron from July to September 1944: 1117 rockets were released and pilots claimed 85 tanks knocked out and another 29 damaged and 164 other vehicles knocked out and 23 more were damaged (in reality, the figures were lower, I pressume, as later investigation teams usually confirmed only a smaller portions of such kills byaircraft weapons). Even though the training of American pilots was not that extensive as of British counterparts, the experimental phase of using HVARs was considered fairly successful.
Ninth Air Force's fighter groups which were operated in Bohemia in April and May 1945 were also equipped with HVARs – the 368 FG was particularly active on April 29 and 30. According to their mission reports they fired 24 and 20 rockets, respectively, at rail and road traffic in Bohemia, which is in total one fourth of all rockets used during this month!
Sources:
GOODERSON, Ian. Allied Fighter-Bombers versus German Armour in North-West Europe 1944-1945: Myths and Realities. Journal of Strategic Studies. 1991, vol. 14, No. 2, s. 210-231.
ČERNÝ, O. Letecké raketové střely. Letectví. 1946, roč. 22, č. 4, s. 111-113.
SPIRES, David N. Air Power for Patton: The XIX Tactical Air Command in the Second World War. Washington, D. C. : Air Force History and Museums Program, 2002, s. 63-64 Available at: <https://www.airforcehistory.hq.af.mil/Publications/Annotations/spireair.htm>. ISBN 0-16-051081-3.
