The answer is Royal Scottish Air Force (RSAF) along similar lines to the Royal Canadian Air Force (RCAF), Royal Australian Air Force (RAAF) and Royal New Zealand Air Force (RNZAF). Any confusion with the modern day Royal Saudi Air Force is unfortunate but as you will see from my backstory, Scotland got there first!
My backstory...
This timeline is set in a Scotland that shares a geographical and economic arrangement with England similar to modern day Canada and the USA but with a constitutional arrangement more akin to New Zealand and Australia.
Scotland and England have shared a monarch since the Union of the Crowns in 1603, when King James VI of Scotland inherited the English throne from his double first cousin twice removed, Queen Elizabeth I. Although described as a Union of Crowns, there are in fact two separate Crowns resting on the same head (as opposed to the implied creation of a single Crown and a single Kingdom). There have been three attempts in 1606, 1667, and 1689 to unite the two countries by Acts of Parliament, but ultimately all proved fruitless for a variety of different reasons. It was not until the early 18th century that both political establishments came to support the idea, of a constitutional, economic and by association, military alliance in the shape of a commonwealth of nations.
The Acts took effect on 1 May 1707. On this date, the Scottish Parliament and the English Parliament formally established the Commonwealth of Great Britain. On the Commonwealth, historian Simon Schama said "What began as an economic merger, would end in a full partnership in the most powerful going concern in the world ... it was one of the most astonishing transformations in European history."
During WW1, the armed forces of Scotland and England fought alongside the other major member nations of the now expanded Commonwealth (England, Scotland, Canada, Australia, New Zealand, India and South Africa). In a mirror of the formation of England’s Royal Flying Corps (RFC), the Army of Scotland (the Royal Regiments of Scotland) established the Army Air Corps (AAC). As the conflict dragged on into 1918, the lessons learned and technological developments in the employment of air power led the English to establish the world’s first independent air force in the shape of the Royal Air Force (RAF). Five days later the Royal Scottish Air Force (RSAF) stood up as an independent arm of service and thus became the world’s second air force.
During the interwar years, economic and military ties within the Commonwealth continued apace so that by the start of WW2 the militaries of each member nation, whilst not identical, shared common doctrines, training, tactics and the majority of their weapon systems.
Such was the cooperation and interoperability that the northern anchorage of the Royal Scottish Navy (Scapa Flow, Orkney Islands) was also home to a significant proportion of the Royal Navy (RN). Several air bases were constructed to provide local air defence for this critical naval base; the largest of which was Skeabrae AB. With its northerly location also providing access to the Norwegian mainland and coastal waters, Skeabrae AB was, by 1944, home to no less than 9 Sqns of fighters and strike aircraft:
66 Sqn RAF (Spitfire)
118 Sqn RAF (Spitfire)
313 (Czechoslovak) Sqn (Spitfire)
329 (Norwegian) Sqn (Typhoon)
331 (Norwegian) Sqn (Typhoon)
622 Sqn RSAF (Typhoon)
51 Sqn RSAF (Beaufighter)
58 Sqn RSAF (Beaufighter)
253 Sqn RNZAF (Beaufighter)
My model will depict a RSAF Typhoon of 622 Sqn, of the Skeabrae AB Long-Range Fighter Wg in June 1944.