PZL.37 Łoś – a medium, twin-engine bomber of Polish design and production, built as a low-wing all-metal low-wing bomber with a retractable landing gear. Production of the first B series units began in the fall of 1938. They were modeled on the P.37/II prototype with corrections resulting from operational experience. The main difference between versions A and B were more powerful engines and better design. The new aircraft use Bristol Pegasus XX engines (918 HP) or the same engines built under license in Poland as PZL Pegasus XX. By September 1, 1939, the factories: PZL-WP No. 1 in Warsaw and PZL-WP No. 2 in Mielec (operating from August 1, 1939) managed to produce a total of about 120 PZL.37 A and B bombers. [wiki]