The past three decades have seen a number of less-than-successful efforts to develop high-altitude unmanned aerial vehicles. In 1994, the Defense Advanced Research Projects Agency, in conjunction with the Defense Airborne Reconnaissance Office, initiated an effort — designated the High-Altitude Endurance Unmanned Aerial Vehicle Advanced Concept Technology Demonstrator (HAE UAV ACTD) — whose goal was to facilitate the development of UAVs through the use of a new and innovative acquisition strategy. This report addresses the effect of that acquisition strategy on the flight test program of the two air vehicles: the conventional Global Hawk and the low-observable DarkStar. The authors found that because DarkStar was canceled after having logged only 6.5 flight hours, not enough flight experience was accumulated to allow for an understanding of the vehicle's flight characteristics or military utility. By contrast, Global Hawk accumulated ample experience to permit a demonstration of its military utility, achieving a level of performance that was close to predicted goals. The precise effect of the HAE UAV acquisition strategy remains the subject of debate. The strategy did, however, influence some key aspects of the flight test program, most notably its increased contractor involvement and its early operational testing in the form of user demonstrations. The flight test program also served to illustrate the vital need for early involvement of operational users to bolster the capabilities and perspective of the contractor.