The Saab 21 is a unique two-seat fighter aircraft produced by the Swedish company Saab. This aircraft was developed during World War II, when the Swedish government was looking for a way to defend their airspace against the increasing threat of German aircraft. The Saab 21 was chosen as the best option in terms of cost and capabilities.

The Saab 21 was designed as a two-seater aircraft, with the pilot and gunner sitting in tandem. It was powered by a single engine, the Saab SFA-9, which was a modified version of the Junkers Jumo 211 engine. This engine allowed the Saab 21 to reach a maximum speed of 550 km/h and a range of 1,000 km.

The Saab 21 was designed to be an agile aircraft, with a low wing design, a retractable undercarriage, and an ejection seat for the pilot. It was also equipped with a variety of weapons, including two 20mm cannons, two 12.7mm machine guns, and two additional machine guns in a trainable rear mounting.

The Saab 21 was a highly successful aircraft, and was used by the Swedish Air Force until the mid-1960s. It was also exported to a number of countries, including Denmark, Finland, and Norway. In addition, the Saab 21 was used by several air forces during the Korean War, and was a key part of the Swedish-led UN forces in the conflict.

Despite its success, the Saab 21 had a number of safety issues over its lifetime. In particular, the aircraft was prone to engine fires, which could be caused by a number of different factors, including improper maintenance. In addition, the aircraft also had some issues with wing flexing, which could cause a loss of control.

Despite these issues, the Saab 21 was an innovative aircraft, and incorporated a number of new technologies. These included the use of pressurized cabin and cockpit, a retractable undercarriage, and an ejection seat for the pilot. These features made the Saab 21 more advanced than other aircraft of its era.

The Saab 21 was also highly maneuverable, and could out-maneuver many of its contemporaries. This made it a formidable opponent in air-to-air combat, and it was used to great effect by the Swedish Air Force during the Korean War.

Today, the Saab 21 is still a popular aircraft, and is used by a number of air forces around the world. It is also a popular aircraft for civilian use, and can still be seen in the skies over Sweden and other countries. Despite its age, the Saab 21 still remains an impressive aircraft, and one that has stood the test of time.