The slippers were the four “feet” which supported the missile when it was on the launcher. The heavy forged parts slipped into square receptacles on the lower side of the missile and were automatically air ejected after launch. The free end of these ”Z”-shaped forgings had a heavy bronze shoe attached which rode inside the launch rail. The bronze shoe plus lots of lubricating grease reduced the sliding friction during the launch.
A parabrake was used to slow the missile during the landing rollout. The 16-foot ribbon-type parabrake was sequenced to deploy when the nose gear touched down and the nose gear strut compressed. The parabrake “pan” was on the lower right hand side of the aft section with a heavy steel cable routed to an attachment at the rear of the missile. The door to the parabrake pan was expendable and replaced after each successful landing. Some problems were experienced with the parabrake during early test flights. On the first successful flight (FTV-2) the parabrake deployed, blossomed, then collapsed. The drag chute failure was the only malfunction on an otherwise perfect first flight.
Realizing that a speeding missile at high altitude would be very hard to see, the designers included a smoke system as a tracking aid. A light fuel oil was stored in an onboard tank and pumped into the engine exhaust just aft of the end of the missile. Smoke “on” or “off” could be selected when desired. When selected, the normal mode was a series of intermittent puffs to show the position of the missile. However, should the radio control carrier signal drop below a preset minimum for more than six seconds, a steady stream of smoke was generated as a visual indicator to the chase pilots that carrier had been lost. The proportional controls then moved to zero pitch, zero bank and ninety-percent throttle. Unless control was re-established before 30 seconds had elapsed, fuel cut-off occurred and the missile was programmed into a vertical dive.
The JATO/boost rocket system used a pair of Aerojet General solid fuel boosters with a 2.2 second firing time, with each producing 33,000 lb of thrust. The boosters were attached to each side of the missile and ejected by compressed air upon burnout. Each booster had an adjustable nozzle which was carefully aligned to ensure the thrust vector went through the missile center of gravity.
The proper alignment of the JATO thrust vector was vital for a successful launch, and yet not all that easy to do. When the alignment was not correct the missile rotated on launch rather than being boosted upward into the correct flight path. Several different alignment systems were used at various times, still some missiles were launched with incorrect booster alignment with subsequent loss of the missile.
More Regulus I:
General Characteristics for an Interim Guided Missile