Bell L-39

The Bell L-39 was an experimental aircraft that Bell Aircraft built to test the low-speed characteristics of swept wings. After the Second World War the United States military took an interest in German research into swept wings, and the US Navy contracted Bell to modify two P-63 Kingcobras for use by NACA. Each was fitted with straight inner wing panels and 35 degree swept outer panels derived from the P-63E, with cameras behind the canopy to film airflow over wing tufts and leading-edge slots that could be bolted on in different configurations. The first, the L-39-1, flew on 23 April 1946 with Bell test pilot Alvin Johnston, and slotted wings of 60 and 80 percent were found to give excellent stall characteristics. The programme was halted on 26 August 1946, one aircraft later supported the Bell X-2 programme with a fully swept wing, and both were sold for scrap in 1955.