The S1010 and several S1010 dash variants were later replaced by a further advanced model, the S1031 PPA. The S1031 special projects full pressure suit came in 12 sizes and was used in the TR-1 and U-2R. In the early 1980s efforts to produce a standard single suit capable of being used by both SR-71 and U-2 crews, yielded the S1031C suit, replacing earlier suits on an attrition basis.
The David Clark S1030C and S1010B suits were precisely fabricated, multi-layered garments, weighing about 16 kg each and available in 12 standard sizes. When they were first produced in the late 1970s, each individual assembly initially cost the US Government over $30,000. The per-unit purchase cost of the newer S1031C PPA was nearer $100,000 and the expense of completely rebuilding one was almost as much.
The seven layers of specialized protection included long underwear, a comfort liner, a ventilation layer, a double-walled pressure containment layer, a restraint layer and a gold fabric outer layer (the gold-orange color of which was officially referred to as 'old gold'). The helmet featured an internal sizing and fitting system originally pioneered by the US Navy in its FPS developments of the late 1950s and had a sealing (clear) and non-sealing (tinted) visor. Tubular ports for entrainment of special food and fluids in extruded aluminum squeeze tubes are provided in the chin area.
Donning of the earliest suits took about 45 minutes with the help of two technicians and the services of the PSD (Physiological Support Division), although the donning time was substantially reduced in the latest model S1034 PPA. Many of the features of the suits were advancements of systems pioneered in earlier precursors made by the David Clark Company subsequent to the introduction of the archetypal XMC-2-DC model (precursor of the USAF A/P22S-2 suit, used extensively in the X-15 project) with vastly improved, new-generational systems developed from original combined US Air Force and US Navy FPS research programs.
The latest of the S-series suits, of which the S1031C PPA was a good example, are equipped with a urine collection system that permits excreted urine to be dispersed in special lower leg semi-solidification storage areas. Each was integrated to an outer combined parachute harness/vest assembly fabricated from the same 'old gold' colored material as the outer layer of the suit (the harness/vest assembly incorporated a life preserver system and automatic seawater-activated parachute riser releases called SEAWARS fittings). Internal pressurization was maintained at a constant 0.24 bar utilizing considerably advanced generational developments of the original US Navy aneroid type suit controller principle. The David Clark suits protected pilots of the SR-71 and U-2 type aircraft at high altitude for over four decades.