In 1936, Andromedian High Command called for a bomber aircraft with a top speed no less than 350 miles per hour. Proteus Industries immediately produced the Sunbeam, with powerful engines propelling the aircraft above 380 miles per hour. This propelled immediate concern with the Kenkuni High Command, as reconnaissance images revealed the aircraft had large wings, suggesting a heavy fighter with great maneuverability. However, a mechanical malfunction in the battle of Caledonia forced a Mk. I Sunbeam down behind enemy lines. In very short order, engineers repaired the damaged plane enough to send it to Jouto-Ude's Aeronautical Engineering department. As it turned out, the aircraft's weight necessitated its large wings. The engineers also uncovered more features of the design:

The aircraft was largely made of Stainless Steel, hence its large empty weight of 15,343 pounds. The wings also lacked the strengthening structure to handle the G-loads a fighter could endure, hence reports of the aircraft not being used in the fighter role.

It also only bore two 7.62mm machine guns, which indicated the aircraft was not a heavy fighter as the Kenkuni High Command had feared

The aircraft's cockpit doubled as an escape capsule, allowing even an injured pilot to have the chance of survival when most designs required pilots to jump clear. Still, the cockpit, also being made of stainless steel, sunk in water. However, the escape capsule design did buy the pilot enough time to ensure his life jacket inflated and unclipped his harness.

The turbosupercharger system, while powerful, was only optimized for altitudes below 10,000 feet, meaning the aircraft developed a severe power loss above that altitude.

As a result of the captured Sunbeam, Andromedian designers started working on improving their designs further:

The Mk. II added fins to the design, and a lengthened tail improved rudder authority to ensure the aircraft could take off should an engine be lost, as well as better armament to take out tanks.

The Mk. III Had slight redesigns to the fins to correct the directional instability which resulted from the center of aerodynamic pressure being shifted forward, as well as stronger wings to ensure the aircraft could withstand damage more easily. However, this also allowed the aircraft to perform surprisingly well as a fighter. The turbosupercharging system was improved, to lessen the rate of power loss as the aircraft climbed past 10,000 feet

The Mk. IV sunbeam, which is the design in the image, had a revamped turbosupercharging system, which ensured the aircraft now could fly up to 30,000 feet, compared to 10,000 in the Mk. III versions and earlier.