The tail plane featured two large oval vertical stabilizers mounted at the ends of a rectangular horizontal stabilizer. As early as 1942, it was recognized that the Liberator's handling and stability could be improved by the use of a single vertical fin. The single fin was tested by Ford on the single B-24ST and an experimental XB-24K, and was found to improve handling. All Liberators were produced with twin oval fins, with the exception of eight preproduction B-24N aircraft. The B-24N was intended as a major production variant featuring a single tail. Over 5000 orders for this version were placed in 1945, but were cancelled due to the end of the war. The single fin did appear in production on the PB4Y Privateer derivative.