This type was built following a request by the Ministry of Railways for a survey aircraft for the Shin Tokaido railway Line which was to be built from 1939. The KKY-2 version was modified with a large window in the rear of the cabin and another one in the cabin floor. Instead of stretchers and patients the cabin could accommodate three surveying passengers as well as equipment for mapping and aerial photography. A large automatic aerial camera was also installed and the Tachikawa designation KS meant Kogata Sokuryoki (Small Survey Aircraft).
Two were built, the maiden flight of the first was in May 1939 and received the registration J-AARD which is the subject of the Amodel kit. There is no information regarding the second KS-1.
Below is a photo from a vintage publication of rather poor quality (our apologies) that shows the markings apart from the J- registration that seem to be missing from the box art of the kit.
The inscription on the side of the fuselage and on the tail read "Tetsudosho 5go" (Ministry of Railways No. 5) and looked very similar to this:
Tachikawa KS-1 Data:
Wing: wooden, fabric covered / Fuselage: welded steel tube, fabric covered.
Engine: Jinpu Model 3 150hp air-cooled radial 7 cylinders / Propeller: Wooden, two blades Model Otsu fixed pitch, diameter 2.2m / Span: 9.996m / Weight, empty: 722kg, full: 1,140kg, cargo: 358kg / Power loading: 7.6kg/hp / Fuel: 2 tanks 140+69lit / Fuel type: 62 Octane
Max speed: 185km/h @ 1,000m / Cruising speed: 135km/h @ 1,000m / Landing speed: 80km/h / Climb to 3,000m in 33.35min / Take-off distance: about 250m / Crew: 4