The Kjeller PK X-1 was a two-seat helicopter developed at Kjeller Flyfabrikk under the direction of civil engineer Paul Kjølseth . The PK X-1 first flew in 1955. It was a purely experimental helicopter. Further development of the PK X-1 was cancelled in 1956 in favor of the development of the PK X-2. The PK X-1 was equipped with a Ranger 6-cylinder in-line engine of 200 hp.

Built as the initial RNoAF helicopter but never entered production