In 1953, Aurian Sea Organisation (ASO) member Kallego announced their desire to procure a method to spy on Rexington pact activities deep into the Arctic, as well as the activities of nations further from away from the central continent of Euro. This was revealed the Kallegian Defense Paper of 1953, which outlined that even though the primary nations of the ASO (Kallego and Aldel) and the Rexington pact (Andalowë, The Nord and Miyateska) were in close proximity to each other, the Rexington pact held an advantage in which they could develop items out of the prying eyes of the ASO by hiding them in the arctic circle (primarily Nordic and Miyateskan territories), much farther than the ASO's reconnaissance aircraft could reach without interception at that time. The paper called for a design that could fly faster and higher than all intercepting aircraft known to the nation, in service by 1960. In 1954, Long-Range Reconnaissance Aircraft (LRRA) program was announced, the requirements of which being an aircraft capable of Mach 3, a service ceiling above 20,000m, a range of 1,500 miles or greater and carrying a payload of a ground imaging radar, and a reconnaissance camera unit to be developed concurrently. Several aircraft builders and reconnaissance systems companies would send in designs.
Stenson Aircraft would be chosen with their aircraft proposal known as SA-203, a twin-engine design theoretically capable of Mach 3, with a crew of 2 (pilot and reconnaissance systems officer) and a service ceiling of 25,000m. The aircraft would be equipped with a ground imaging radar in the nose, and rely on speed, maneuverability and light electronics warfare to combat air defense systems and interceptors. In regards to mission systems, Beecher Company, would be chosen to develop a multiple camera system useable by the aircraft, housed in a pair of bays in the underbody of the aircraft, with a ground resolution of at least 6 inches at 25,000m, designated RC88AU3 (Recon Camera 88, Airborne Unit 3). Further development would be given the government go-ahead in 1955, including refinement of SA-203, which would hit a rut not a year later, resulting in the delaying of the initial plans for a first flight by 1959. Kallegian engine manufacturer Mobley would be brought onto supply the engines designated AJ93. Delays in delivering the first unit of SA-203 would mean that engine testing would be independent of the airframe for a longer period than expected. Owing to the size of the unit, the AJ93 would be tested on several Kallegian bombers in the meantime, to which it was noted that the engine "produced enough thrust to jeopardize the structural integrity of whatever aircraft it was run on", as commented by a technician riding on once such test flight.
In March 1960, the first unit of SA-203, now designated YRS-1 by the Kallegian Air Force, and known unofficially as the Skylark by other government agencies, would embark on it's first flight. From then on 5 prototypes were created, and a series test flights would take place between then and 1964, testing the airframe, engines and reconnaissance systems, in which YRS-1 unit #003 would reach a top speed of Mach 3.1 at 25,210m and unit #004 would be lost in an accident. By June 1964, well past the original, the aircraft was considered mission capable by the Kallegian Air force, and was accepted into service officially as the RS-1A Skylark. A total of 32 aircraft would be ordered, and prototype aircraft #002 and #003 would be converted to commission specification for a total of 34 total aircraft.
24 service aircraft (#006-030 would be located in fellow ASO nation Fuyukawa, who of all members of the ASO, owned the closest airbase to the primary projected mission area of the Arctic Circle, Holburn Air Base. There, the aircraft would take off, be refueled by a loitering tanker, and fly over the Arctic to skirt the northernmost border of Miyateska and The Nord at an altitude of 25,000m, where they would take pictures of military activities taking place, mapping the locations several nuclear testing and launch facilities, before returning to Holburn for image processing and maintenance. The remaining 10 aircraft would operate on the Southern Continent, Kallego's home territory, where they would engage in reconnaissance on nearby nations that share sentiments with the Rexington Pact, and would assist in several clandestine operations to dissuade such nations from joining the Pact. It is also suspected that several of Skylarks were pivotal in the planning and execution of the War for Turic (Invasion of Turic to non-ASO nations), in which Turic, a set of neutral islands off the northwestern coast of Kallego, announced their intent to align themselves closer to Rexington Pact, and were subsequently invaded in 1965, capitulating in 1969.
The skylark flew uncontested from its introduction until 1969, where Andalowë would introduce their new fighter aircraft, the Vantel 21. Though it was expected not to be able to intercept the Skylark, it was apparent that the advances in technology shown over the Vantel 19, as well as increasingly more advanced surface-to-air missile technology meant that by the mid-70's, the Skylark would not be able to fly as liberally as it usually could. Therefore, upgrades would begin development in late 1969, the result of this being the RS-1B, the first major upgrade for the craft which sought to increase the speed and altitude at which the aircraft operated, including an increase in thrust for the engines, as well as new reconnaissance cameras (RC90AU5) to compensate for the altitude increase. 3 aircraft (#013, #018 and #021) were pulled from regular service and tested the new upgrades, however severe issues came from the upgrading of the AJ93's resulting in the crash of #021 and the severe damage to #018, which was later scrapped. As such the program would consist only of the new camera system and a flare and chaff system to countermeasure incoming missiles, introduced in 1975. Though the upgrade increased the operation capabilities of the aircraft, the systems were reaching their end of service. Though the system was never the most reliable, a series of hull losses and other minor accidents after the upgrade would force Kallego to reconsider their use of the system, and, in The Kallegian Defense Paper of 1981, increasing costs of maintenance, were cited as reasons for retiring the Skylark by 1990. The aircraft would see it's last mission on Septemer 15th 1989, in which it observed a significant geological event in the eruption of Mount Kiriani whilst spying on neighbor nation Crelia. After decommissioning, some of the surviving aircraft would be placed in museums, with 12 located in Kallego, 3 in Fuyukawa and at 1 in Aldel. 2 were retained for further use until 2004 as airborne research aircraft by KASA, Kallego's space agency, before being placed into museums, and the rest would be stripped for parts.