The Perseus design effort struggled along on skimpy funds until 1991, when NASA was conducting a "High Speed Research Program" to evaluate designs for a future supersonic transport, and needed to learn more about the possible environmental impact of such an aircraft on the upper atmosphere. Funds became available to procure a few aircraft.
The Perseus design effort was hampered by limited funding until 1991, when NASA's "High Speed Research Program" provided resources to study the environmental effects of supersonic transport designs and acquire a small number of test aircraft.