NASA and Sunpower free-piston Stirling references (public domain) and design numbers — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/nasa-fpse-references/ (CC BY 4.0) Basis: NASA Technical Reports Server (NTRS): US Government works are public domain. Headline numbers from the published convertor papers (ASRG, GPHS-ESP, TDC, RE-1000, Sunpower EE-35 / Microgen); hobby-scale rules from Urieli / Berchowitz Catalog version: 2026-10-20 Sizes: see table below - Where the real designs are: NTRS (ntrs.nasa.gov) hosts decades of free-piston Stirling work: the Sunpower RE-1000 test engine (1 kW, 1980s, the best-documented FPSE: dimensions, pressures, strokes, phase angles all published), the Stirling Technology Co. 55 W TDC, the Sunpower ASC/ASRG convertors (80 We class, 102 Hz, helium at 3.5 MPa, 850 °C hot end, flexure suspended, 14+ years on test), Glenn's flexure fatigue and life-test reports, and the thermoacoustic (TASHE) work. Search NTRS for 'free-piston Stirling', 'ASRG', 'RE-1000', 'flexure bearing', 'linear alternator'. - Representative numbers: RE-1000: 57 mm bore, 1 kW, 30 Hz, 7 MPa helium, displacer on a gas spring, piston on a gas spring + dashpot load. ASC-E2: ~80 We, 102 Hz, 3.5 MPa He, piston stroke ~5 mm, hot end 850 °C, cold 90 °C, 38% convertor efficiency, flexure-suspended displacer and piston. GPHS-ESP / SRG110: 55 We, 80 Hz. Microgen (Sunpower-derived) domestic CHP: 1 kWe, 50 Hz, helium. - Why it matters at hobby scale: the same physics scales down (resonance, clearance seals, flexures, linear alternator), only the pressure and frequency drop: air at 1 bar, 10–20 Hz, 0.1–2 W. The parts on this shelf (flexures, alternator kit, free-piston core, regenerator media, tri-clamp vessel) are the hobby-scale translation of the ASRG parts list. - Open design tools: Urieli's Stirling cycle machine analysis (ideal adiabatic + simple models, free online); Sage (commercial, used by NASA); Berchowitz & Urieli 'Stirling Cycle Engine Analysis' (1984) is the standard text; Walker 'Stirling Engines' (1980); Senft 'An Introduction to Low Temperature Differential Stirling Engines' for the can-engine end. - Nothing here is NASA's CAD (none is public); the dimensions quoted are from the papers. machine power freq_hz pressure hot_c suspension ntrs_search Sunpower RE-1000 1 kW 30 7 MPa He 600 gas springs RE-1000 free-piston STC 55 W TDC 55 We 80 2.5 MPa He 650 flexures Technology Demonstration Convertor Sunpower ASC-E2 (ASRG) 80 We 102 3.5 MPa He 850 flexures Advanced Stirling Convertor Microgen (Sunpower) 1 kWe 50 He 500 flexures Microgen Stirling LES hobby free-piston 0.1–2 W 10–20 1 bar air 150 printed/steel flexures — Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - NASA (NTRS, public domain): Advanced Stirling Convertor (ASC) development (2010) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=Advanced Stirling Convertor - NASA (NTRS, public domain): RE-1000 free-piston Stirling engine sensitivity test results (1986) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=RE-1000 - NASA (NTRS, public domain): Stirling convertor flexure fatigue testing (2008) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=flexure fatigue Stirling - NASA (NTRS, public domain): Thermoacoustic Stirling heat engine (TASHE) for space power (2004) — PDF — US Government work, public domain — https://ntrs.nasa.gov/search?q=thermoacoustic Stirling - Wikipedia: Advanced Stirling radioisotope generator — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Advanced_Stirling_radioisotope_generator - Wikipedia: Stirling radioisotope generator — web — CC BY-SA 4.0 (text) — https://en.wikipedia.org/wiki/Stirling_radioisotope_generator - Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/ Xem Studio scan: not planned; the official CAD above covers it. API: https://xemstudio.com/api/geometry?object=nasa-fpse-references