In 1941, the Brazilian Air Force (Força Aérea Brasileira) was formed. Almost immediately, the new Ministry of Aeronautics set about establishing an indigenous source of combat aircraft. In response, Companhia Nacional de Navegação Aérea (CNNA) offered its HL-7 Andorinha. The aircraft had been designed by Antônio Guedes Muniz with assistance from Mikhail Goremykin. Goremykin was a Russian émigré to the US where he had worked under Alexander Kartveli of Seversky (later Republic) Aircraft. Goremykin had come to Brazil expressly for this purpose, and brought with him expertise in metal stressed skin structure, as well as some specific design data from the Seversky stable. As a result, the HL-7 bore some resemblance to earlier Seversky designs, especially in the tail.
The wings of the HL-7 were of a new concept created jointly by Muniz and Goremykin. Muniz had studied earlier dive bombers and knew that the wing design limited acceptable speed in a dive. Although he did not understand the concept of compressibility (the US NACA would not solve that problem for another year or more), he knew that existing, thick wings were not adequate. Seeking a solution, he set about to observe fast-flying and diving birds. He was particularly impressed by the various swallows and martins – noting in particular their swept and sharply tapered wings, which they swept even more sharply when diving. He and Goremykin designed a wing that was uncommon for its day in being relatively thin, highly tapered, and moderately swept (18.5 degrees at the leading edge).
In tests, the new wing did not allow the HL-7 to dive at higher speeds as was hoped. The designers were left with the choice of designing and installing dive brakes, or giving up the idea of dive-bombing as a mission for their aircraft. By this time, near-vertical dive bombing was becoming much less in vogue, while multipurpose ground attack aircraft became much more favored. Consequently, the HL-7 was ordered in large numbers for the FAB for the ground attack and heavy fighter roles. Equipped with two 20mm Oerlikon cannon produced in Brazil under Swiss license, the HL-7B was able to carry two 500 lb bombs underwing, and was the main production version. The HL-7 also carried a single .30-calibre machine gun on a flexible mount in the rear cockpit. Three hundred twenty HL-7Bs were built, and served with distinction in Brazil, the Gran Chaco, and Italy.