From what I can find, the only product of the Air Force Sandpiper program to fly was the AQM-81A Firebolt. It was a high altitude, high speed target drone that used the hybrid motor. It was a development of the HAST ( High Altitude Supersonic Target) program which followed on the promising results of the Sandpiper program. But it never went into production. Picture attached from Wikipedia.

Thank you for posting that. I used to have a copy of a videotape (shot at Eglin AFB) from which that picture came, when the MARS--Mid-Air Retrieval System--helicopter lowered the captured-on-'chute Firebolt onto the recovery net. The Firebolt had delta canards with slightly rearward-swept trailing edges, and its wing tip fins had straight, perpendicular (to the wing) trailing edges. I've long wished that a model rocket company would produce a Firebolt kit (its underside air scoop ram-air-driven oxidizer pump air intake could be used--on a model--to make it a ducted rocket). Scale models of any of these vehicles (AQM-37, Sandpiper, HAST/HAHST, Firebolt) would make super-fast RC rocket planes, but perhaps only someone like Ali Machinchy, who has cat-like reflexes (see: www.youtube.com/watch?v=orGca6G84U8 ), could fly them.