In the 1970s Germany put out a requirement for a new fighter, called Taktisches Kampf-Flugzeug 90 (TKF-90, Tactical Fighter Aircraft), to which Dornier responded by forming a collaboration with Northrop in America because of Northrop's considerable experience in producing compact fighters. In 1978, Dornier & Northrop tested a series of tailed and tailless fighter concepts incorporating state of the art aerodynamics, avionics & propulsion systems. 34 configurations were examined in 1200 hours of wind tunnel tests. What emerged in mid 1982 was a configuration with a gross weight of 25,000lb which bore strong resemblance to the SAAB Gripen, both in shape and size. Significantly, the necessity of either a canard or tailplane for pitch control was eliminated, to be substituted by thrust vectoring engine nozzles. In an even more unusual step, it was decided to use non-afterburning low bypass ratio turbofan engines in the form of 2 Pratt & Whitney 1120s, but it was projected that the aircraft would still be capable of supersonic flight, up to Mach 2. This is very revealing in the light of the performance requirements of the ATF. The implication was that very high speeds were feasible without the use of afterburner as far back as the early 80's, and that the true supercruise capability of the ATF PAV's may have been far higher than publicised. A joint total of $20 million was invested by the 2 companies and the concept was shown in model form at the Paris Air Show in 1983. It was called the ND-102 'International Fighter'. It did not go ahead and was cancelled in 1984.

The reason it is mentioned here is because of its highly influential configuration. It showed where Northrop's thinking was headed, and was the first publicly revealed example of Northrop's idea for a clipped diamond wing. The design clearly showed the next step after the F-18 Hornet, and set a precedent of tailplane elimination coupled with thrust vectoring that was to become very popular amongst the concepts submitted for the ATF 1982 formal RFI. We see here angles in the leading and trailing edge of the wing that are close to optimal, later to be echoed in the Eurofighter and YF-22. Although the ND-102 concept was displayed with a single vertical fin, a twin fin configuation was tested in the windtunnel: further hint of what was to come. The ND-102 configuration was the true predecessor of the YF-23.

Reference sources:
Air International June 1983: 'Aircraft Design Philosophy' by Lee Begin
Defence & Armament July/August 1983
Supersonic Fighter Development, by Roy Braybrook, Foulis 1987
Warplanes of the Future, by Bill Gunston
X Planes Profile 1, Prelude to Eurofighter: EAP, by Henry Matthews, HPM 2000