The CL-1200 competed unsuccessfully against proposed fourth generation designs, under the US government's Lightweight Fighter program, which would eventually result in the General Dynamics F-16 and Northrop F-17 Cobra (precursor of the McDonnell Douglas F/A-18).
[1] Borrowing heavily from the F-104 design the new type featured a new high-mounted, increased span wing and low-mounted, enlarged tailplanes.
Since the Northrop F-5 was named the winner in November 1970, the primary market for the Lancer was lost, and the project was terminated with no aircraft completed.
The X-27 was an experimental designation assigned by the USAF[1] to a proposed high-performance research aircraft derived from the CL-1200 Lancer project.
Clarence L "Kelly" Johnson headed the department during this period, while Skunk Works designers carried out all aerodynamic studies and wind tunnel testing on the type.
Unlike the F-104, the rear fuselage section was to be constructed using titanium alloy for the frames, longerons and skinning around the jet exhaust.
The tailplane was increased in area, split into two separate surfaces, and moved from atop the vertical fin to the lower rear fuselage to avoid the downwash effects from the high-set wing at high angles of attack which could have resulted in a deep stall condition.
The second, more advanced variant, the CL-1200-2, was to have redesigned center and rear fuselage sections that could accommodate a modern turbofan engine as an improvement on the J79 turbojet.
External fuel tanks of the same type and capacity as the F-104 could be carried on the wing tips and on underwing pylons to increase ferry range.
[5] The estimated gross weight was 35,000 lb (16,000 kg) with maximum external load, and a top speed of 1,700 mph (2,720 km/h, Mach 2.5) at 35,000 ft (10,700 m) was envisaged.
The takeoff run was estimated to be 1,450 ft (440 m) in the intercept configuration; only 52% of that required for the F-104G with a similar improvement on landing performance due to the slower approach speed.
[6] Lockheed carried out a comprehensive survey and believed that there was a worldwide market for an advanced design, low-price fighter aircraft over the decade of the 1970s.
Another cancelled Starfighter derivative, pre-dating the CL-1200 Lancer by eight years and not directly related, was the CL-704 VTOL strike and reconnaissance aircraft originally proposed in 1962 as a joint venture between Lockheed and Short Brothers and Harland Ltd.
Designed purely for VTOL operations, it would have seven vertically-mounted Rolls-Royce RB181 lift engines in each of the enlarged wingtip pods.
[7] A larger-winged F-104 variant was proposed as an alternative to the MRCA (Multi-Role Combat Aircraft) then being designed as a multi-national European project.