Xem Studiomeasured geometryThermoacoustic-Stirling engine with twin free-piston alternators, 2 in, pressurised
Backhaus & Swift's thermoacoustic-Stirling torus in 2 in tri-clamp with two opposed free-piston alternators on the junction cross, a jet pump, helium charge and a torch drum.
20 bar helium · 24 Hz · onset 204 °C with the alternators open · ≈ 9 W electric for ≈ 67 W into the hot exchanger (14 %) at ±8 mm (model)
Exact dimensions. Every part is drawn at true size with no printing tolerance; each part's page lists its mating features and the fit each joint needs, so open those by your process's clearance before making the parts.
Long Earth Society build part. Complete parts list. The engines
51 parts, every one a file here · all STL URLs · Markdown · tick lines as you go (saved in this browser)
| subsystem | object | parts | qty | note | |
|---|---|---|---|---|---|
| None | Tri-clamp spools to a custom length (fab | spool-2in-310.7mm STEP · STL | 1 | core: plain 2 in tube with full ferrules | |
| None | Thermoacoustic bore spacers and liners f | ta-spacer-2in-8.4 STEP · STL | 2 | gasket lip to each ambient exchanger | |
| None | Thermoacoustic slotted exchanger insert | hx-insert-2in-14 STEP · STL | 2 | main ambient (top) and secondary ambient (bottom) exchanger | |
| None | Regenerator screen disc | screen-disc-47.5-m100 STEP · STL | 550 | regenerator: 110 mm of 100-mesh × 0.10 screen | |
| None | Thermoacoustic slotted exchanger insert | hx-insert-2in-12 STEP · STL | 1 | hot exchanger | |
| None | Thermoacoustic buffer-tube liner | tbt-liner-2in-140 STEP · STL | 1 | thermal buffer tube | |
| None | Sanitary clamp crosses (9MP) | cross-2in STEP · STL | 1 | the junction: core up, inertance down, a piston each side | |
| None | Thermoacoustic jet pump | jet-pump-2in-30 STEP · STL | 1 | in the cross's lower branch, on the gasket lip: stops the steady flow round the torus | |
| None | Tri-clamp end caps with a welded boss (f | cap-2in-x-0.75in-ferrule STEP · STL | 2 | top of the core and bottom of the cross: the ¾ in inertance line joins here | |
| None | Tri-clamp honed cylinder spool | spool-2in-6in-honed-48.00 STEP · STL | 2 | piston cylinders, either side of the cross | |
| None | Free-piston mover for a 2 in honed spool | mover-core-2in-130 STEP · STL | 2 | ||
| None | Free-piston mover for a 2 in honed spool | mover-sleeve-48x130 STEP · STL | 2 | ||
| None | Neodymium block magnets | magnet-block-30x10x4 STEP · STL | 96 | 48 per mover | |
| None | Linear-alternator stator that clamps rou | stator-bobbin-half-2in-112 STEP · STL | 4 | ||
| None | Linear-alternator stator that clamps rou | stator-coil-2in-14x7 STEP · STL | 8 | ||
| None | Linear-alternator stator that clamps rou | stator-iron-half-2in-112 STEP · STL | 4 | ||
| None | Socket head cap screws | shcs-m4x16 STEP · STL | 14 | return-shell ears (12), fin-sleeve ears (2, optional) | |
| None | Tri-clamp flexure carrier | flexure-carrier-2in-60 STEP · STL | 2 | outboard of each cylinder | |
| None | Planar spiral flexure bearing leaves | flexure-40-3arm-w1.6-t0.5 STEP · STL | 8 | two per stack, opposite spiral hand | |
| None | Flexure stack spacer ring | spacer-40-t2 STEP · STL | 4 | ||
| None | Flexure rim clamp plate | clamp-plate-40 STEP · STL | 4 | ||
| None | Flexure hub washer | hub-clamp-40-b4 STEP · STL | 4 | ||
| None | Socket head cap screws | shcs-m3x10 STEP · STL | 12 | stack rims into the carrier ledges | |
| None | Threaded rod | rod-m4x195.9 STEP · STL | 2 | ||
| None | Hex nuts | nut-m4 STEP · STL | 33 | hub nuts (8), return-shell ears (12), drum tabs (3), hangers (4), jackets (4, optional), fin sleeve (2, optional) | |
| None | Flat washers | washer-m4 STEP · STL | 8 | under each hub nut | |
| None | Tri-clamp spool (two ferrules on a tube) | tc-spool-2in-12in STEP · STL | 2 | bounce spaces outboard of the carriers | |
| None | Tri-clamp end cap | tc-cap-2in-flat STEP · STL | 2 | close the bounce spools | |
| None | Tri-clamp gasket | tc-gasket-2in STEP · STL | 11 | Type B profile at every 2 in joint, rated above the relief setting at the joint's temperature | |
| None | Sanitary clamp elbows | elbow-90-0.75in STEP · STL | 4 | ||
| None | Sanitary clamp spools | spool-0.75in-12in STEP · STL | 2 | bottom and top runs | |
| None | Sanitary clamp spools | spool-0.75in-3in STEP · STL | 1 | riser, lowest spool | |
| None | Sanitary clamp spools | spool-0.75in-6in STEP · STL | 1 | riser, top spool | |
| None | Tri-clamp spools to a custom length (fab | spool-0.75in-80.4mm STEP · STL | 1 | riser between the tee and the cross | |
| None | Sanitary clamp tees and short-outlet tee | tee-0.75in STEP · STL | 1 | fill branch | |
| None | Sanitary clamp crosses (9MP) | cross-0.75in STEP · STL | 1 | gauge and relief branches | |
| None | Tri-clamp end caps with a welded boss (f | cap-0.75in-x-1-4npt STEP · STL | 3 | close the branches; each carries a 1/4 NPT instrument | |
| None | NPT male thread envelopes 1/8 to 1 in (A | npt-1-4-male STEP · STL | 3 | 1/4 NPT stems of the fill valve, pressure gauge and relief valve | |
| None | Sanitary clamp gaskets | gasket-0.75in STEP · STL | 15 | Type B profile at every ¾ in joint | |
| None | Thermoacoustic burner drum | drum-single-lower STEP · STL | 1 | round the hot zone; flue to the front, down to the torch | |
| None | Thermoacoustic burner drum | drum-single-upper STEP · STL | 1 | ||
| None | Socket head cap screws | shcs-m4x20 STEP · STL | 7 | drum tabs (3), hangers (2 per hanger) | |
| None | Torch stand for a horizontal tri-clamp h | torch-stand-40 STEP · STL | 1 | on the bench under the flue; propane / butane torch head in its ring | |
| None | Set screws (grub screws) | set-m4x10 STEP · STL | 3 | centre the torch head | |
| None | Thermoacoustic water jacket | ta-jacket-half-2in-14 STEP · STL | 4 | optional: over the two ambient exchangers | |
| None | Socket head cap screws | shcs-m4x25 STEP · STL | 4 | optional: jacket ears | |
| None | Thermoacoustic fin sleeve | fin-sleeve-half-2in-34 STEP · STL | 2 | optional: over the hot exchanger inside the drum | |
| None | Hanger post | hanger-post-2in-h235.3 STEP · STL | 2 | under the bounce spools: the engine stands on these two posts | |
| None | Spool hanger collars | hanger-2in-tab STEP · STL | 2 | round the bounce spools, bars to the posts | |
| None | Spool hanger collars | hanger-2in-plain STEP · STL | 2 | ||
| None | Socket head cap screws | shcs-m5x16 STEP · STL | 4 | hanger bars into the posts' tapped holes |
Assembled engine
A pressurised thermoacoustic-Stirling engine in 2 in tri-clamp with two opposed free-piston alternators on a junction cross, a vertical core with exchanger inserts and screen regenerator, a jet pump, a ¾ in feedback line with fill, gauge and relief ports, a burner drum and flue, standing on two posts; about 1239 × 493 × 726 mm.
Assembly STEP (6.0 MB) · STL (9.5 MB) · 850 parts
Build order
- Posts on the bench under the two bounce spools: the whole engine stands on them, the core upright on the cross.
- Core as on the ring engine (550 screen discs, 140 liner); 2 in cap with the ¾ in ferrule on top; the core on the cross.
- Jet pump into the cross's lower branch, small end down, on the gasket lip; 2 in cap with the ¾ in ferrule under it.
- Two power modules as on the ring engine, horizontal, one each side of the cross; 12 in bounce spool and flat cap outboard of each carrier; hangers round the bounce spools bolted to the posts.
- Drum round the hot zone, flue to the front over the torch stand; ¾ in line from under the cross round to the top cap with the fill tee and the gauge-and-relief cross; jackets (optional); charge, leak-check, load connected before lighting.
Agents: each row's object has /api/geometry?object=slug and the MCP tool get_free_files; the STL list above is every part.