He became commanding officer of Blekinge Air Force Wing (F 17) on 23 June 1944 and was promoted to colonel on 1 July 1947. Rapp became Vice Chief of the Air Staff on 1 October 1948 and was a member of the Swedish Armed Forces School Study from June 1950 to March 1952. He was a member of the board of the Swedish Officers Association on 25 November 1950 and became commanding officer of the Fourth Air Group ("Fjärde flygeskadern", E 4) on 1 April 1951. Rapp became commander of the Third Air Group ("Tredje flygeskadern", E 3) on 1 July 1954 and was promoted to major general on 1 October 1955. He became acting head of the Aircraft Department of the Royal Swedish Air Force Materiel Administration on 1 July 1956 and became a member of the board of the National Aeronautical Research Institute in 1957.