Here's a brief summary from one source, Gunther's Space Page:
Project Pilot was the first attempt to create a air launched satellite launch vehicle. The vehicle was better known by its nickname 'NOTSNIK', a combination of NOTS and Sputnik. The NOTS-EV1 was also the first all solid orbital vehicle. It was launched by a Douglas F-4D1 Skyray airplane. After separation from the aircraft, the first pair of HOTROC motors, derived from the SUBROC anti submarine missile, were ignited. Five seconds later, the second pair was ignited. After jettisoning the first stage, the X-241 and NOTS Extruded motors put the payload into a transfer orbit, which was circularised half a orbit later by the fourth stage, which was mounted backwards in fron tof the payload. As the vehicle was designed for maximum simplicity it featured no moving parts.
This would be a cool subject for a semi-scale build. Canted motors with parallel staging for stages one and two (the main visible motors). Going all the way to 5 stages would be a tad complex for me ;) R2K notes that the spherical 5th stage motor was roughly a J700-equivalent.