{"$schema":"nativecad-dfm-pack/1","id":"turbomachinery","title":"Turbomachinery — gas-turbine rotor blades, discs and investment-cast aerofoils","sector":"turbomachinery","version":"2026-09-11","summary":"First-stage HP turbine rotor blade proportions (aero-derivative and industrial-frame classes), fir-tree root and platform geometry, tip-clearance and rotor-speed practice, IN718/IN738LC properties at temperature with a source per value, investment-casting castability limits and the disc/blade tests and tolerances a turbogenerator rotor is held to.","aliases":["turbine blade","turbine","gas turbine","turbomachinery","aerofoil","airfoil","rotor blade","compressor blade","jet engine","turbogenerator","fir tree root","fir-tree root","blade root","turbine disc","rotor disc","nozzle guide vane","stator vane","hp turbine","turbine rotor","investment casting","lost wax casting","superalloy","inconel","in718","in738","turbine rotor blade","hp blade","tip clearance","blade tip","turbine stage","aero-derivative","industrial gas turbine","disc rim","disc burst"],"crossSector":false,"size":"standard","sources":[{"id":"boyce-gas-turbine-handbook","title":"Boyce, Gas Turbine Engineering Handbook, 4th ed. (Elsevier/Butterworth-Heinemann)","accessed":"2026-09-05"},{"id":"nativecad-demo-stage-design-record","title":"NativeCAD's own design record for this invented demo stage — CADSB-857 (vane count) and CADSF-1349 (this entry)","accessed":"2026-09-11","note":"Our own design decisions for a stage that does not exist, not a published measurement of any real engine. Trail: CADSB-857 chose 47, CADSF-1349 made this pack entry its single declared source (FeatureBoard KB doc goodman-inputs-for-in738lc-self-sufficient-acquisition-plan, route 1)."},{"id":"rolls-royce-jet-engine","title":"Rolls-Royce plc, The Jet Engine, 5th ed.","accessed":"2026-09-05"},{"id":"nasa-sp290-turbine-design","title":"NASA SP-290, Turbine Design and Application (Glassman, ed.)","accessed":"2026-09-05"},{"id":"donachie-superalloys","title":"Donachie & Donachie, Superalloys: A Technical Guide, 2nd ed. (ASM International)","accessed":"2026-09-05"},{"id":"asm-handbook-vol15","title":"ASM Handbook Vol. 15 — Casting (investment/shell casting of superalloy aerofoils)","accessed":"2026-09-05"},{"id":"specialmetals-in718","title":"Special Metals Corporation, INCONEL alloy 718 Technical Bulletin (SMC-045)","url":"https://www.specialmetals.com/documents/technical-bulletins/inconel/inconel-alloy-718.pdf","accessed":"2026-09-05"},{"id":"in738lc-published-data","title":"IN-738LC published gas-turbine-literature and OEM material data sheets (Cannon-Muskegon / PCC Structurals cast superalloy data)","accessed":"2026-09-05"},{"id":"ici-design-guidelines","title":"Investment Casting Institute, Investment Casting Design Guidelines","accessed":"2026-09-05"},{"id":"beeley-smart-investment-casting","title":"Beeley & Smart, Investment Casting (IOM3/Maney)","accessed":"2026-09-05"},{"id":"mcdp-investment-casting-guide","title":"Metal Casting Design & Purchasing, \"Investment Casting\" design guide","accessed":"2026-09-05"},{"id":"larson-miller-1952","title":"Larson, F.R. & Miller, J., \"A Time-Temperature Relationship for Rupture and Creep Stresses\", Trans. ASME 74 (1952)","accessed":"2026-09-05"},{"id":"api-616","title":"API Standard 616 — Gas Turbines for the Petroleum, Chemical and Gas Industry Services","accessed":"2026-09-05"},{"id":"lee-2014-in738lc-tmf","title":"Lee, Seok, Lee, Kim, Yun & Koo, \"Prediction of thermo-mechanical fatigue life of IN738LC using the finite element analysis\", Int. J. Precision Engineering and Manufacturing 15(8) 1733-1737 (2014)","url":"https://doi.org/10.1007/s12541-014-0526-3","accessed":"2026-09-11","note":"READ 2026-09-11, open copy at academia.edu/36055330. Table 2: E 157/151/141 GPa, 0.2 % yield 793/552/345 MPa at 760/871/982 C, yield 950 MPa at 21 C, nu 0.28-0.30. The 21 C modulus cell is corrupt. No density, no UTS."},{"id":"schneider-1982-in738lc-hcf","title":"Schneider, Gnirss & McColvin, \"High Cycle Fatigue Properties of Cast Nickel Base Superalloys IN 738LC and IN 939\", in High Temperature Alloys for Gas Turbines 1982, pp. 319-344, Springer","url":"https://doi.org/10.1007/978-94-009-7907-9_13","accessed":"2026-09-08","note":"The abstract states HCF data were generated at room temperature, 650, 750 and 850 C — the measurement this pack needs exists here. The S-N values themselves are paywalled and were NOT read, so the endurance limit stays UNKNOWN rather than being guessed."},{"id":"hoffelner-1982-in738-hcf","title":"Hoffelner, \"High-cycle fatigue-life of the cast nickel base-superalloys IN 738 LC and IN 939\", Metallurgical Transactions A 13A (1982) 1245-1255","url":"https://doi.org/10.1007/BF02645508","accessed":"2026-09-08","note":"HCF at room temperature and 850 C is governed by crack growth from casting pores, with scatter explained by pore size and location — one quoted endurance number for a cast aerofoil is not a safe abstraction."},{"id":"shigley-mechanical-engineering-design","title":"Budynas & Nisbett, Shigley's Mechanical Engineering Design, 10th ed., McGraw-Hill — Ch. 6, Marin endurance-limit modifying factors (Table 6-2 surface, Table 6-5 reliability, Eq. 6-20 size)","accessed":"2026-09-08"},{"id":"nickel-institute-497","title":"The International Nickel Company, \"IN-738 Alloy Preliminary Data\", Technical Bulletin 497 (Nickel Institute reprint)","url":"https://nickelinstitute.org/media/1709/in_738alloy_preliminarydata_497_.pdf","accessed":"2026-09-08","note":"NOT READ - refused by this environment's EGRESS POLICY, not by the Nickel Institute: 2026-09-11, five routes (both NI URLs 403; direct HTTPS logged 'connect_rejected (policy denial)'; Wayback SITE_BLOCKED; specialmetals.ir mirror dead)."},{"id":"eos-nickelalloy-in738-mds","title":"EOS GmbH, \"EOS NickelAlloy IN738\" Material Data Sheet, version 011/2024","url":"https://www.eos.info/05-datasheet-images/Assets_MDS_Metal/EOS_NickelAlloy_IN738/MDS_EOS_NickelAlloy_IN738_en.pdf","accessed":"2026-09-11","note":"READ 2026-09-11. CROSS-CHECK ONLY, NOT a cast source - laser powder-bed additively manufactured, HIP'd, solution treated. Rp0.2 1122/1044 MPa at 25 C, 482/477 at 850 C; Rm 1265/1412, 694/720."}],"entries":[{"id":"hp-blade-aeroderivative-scale","kind":"dimension","tier":1,"title":"First-stage HP rotor blade scale — aero-derivative class","summary":"A 40 klbf-class aero-derivative core's first-stage HP rotor blade: hub radius ~330 mm, span ~60 mm (span:hub ~0.18), ~80 blades on the disc.","applies":["turbine blade","hp turbine","aero-derivative gas turbine","turbogenerator"],"value":{"table":[{"param":"hub radius","mm":330},{"param":"blade span","mm":60},{"param":"blade count","count":80}]},"basis":"Representative dimensions for a 40 klbf-class aero-derivative core's first HP stage: small hub, short span, high blade count vs. an industrial frame","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["turbine-blade","aero-derivative","scale","hub-radius","span"]},{"id":"hp-stage-vane-count-declared","kind":"dimension","tier":2,"title":"NGV count of the demo HP stage, and the vane:blade selection rule","summary":"This demo stage has 47 nozzle guide vanes ahead of its 80 blades — DECLARED, not measured. The rule: vane and blade counts with no low common factor, so engine orders spread rather than cluster, at a vane count roughly 0.5–1.0x the blade count (47/80 = 0.59).","applies":["turbine blade","nozzle guide vane","stator vane","hp turbine","campbell diagram","engine order"],"value":{"value":47,"unit":"count","note":"DECLARED: a design choice of an invented demo stage, on the same footing as its 80 blades and 11,000 rpm — never a measurement. Per-row status is in value.table[].status.","table":[{"param":"nozzle guide vane count","count":47,"status":"declared","basis":"47 is PRIME, so gcd(47, 80) = 1: the vane and blade rows are COPRIME and share no common factor, and 47/80 = 0.59 sits inside the 0.5–1.0x band. A DESIGN DECISION of a stage that does not exist, not a measurement of any real machine (CADSB-857 chose it, CADSF-1349 declared it here)."},{"param":"rotor blade count","count":80,"status":"declared","basis":"the paired rotor row, declared by turbomachinery/hp-blade-aeroderivative-scale — the count this vane count must stay coprime with"},{"param":"vane:blade ratio","ratio":0.59,"status":"derived","basis":"47 / 80 = 0.5875, inside the 0.5–1.0 selection band"},{"param":"vane:blade ratio band","min":0.5,"max":1,"status":"rule","basis":"selection rule: a vane count roughly 0.5–1.0 times the blade count keeps one stage's vane chord and loading sensible"},{"param":"engine orders derived from this count","text":"1, 2, 47, 94","status":"derived","basis":"1/rev and 2/rev for unbalance and a once-per-rev inlet distortion, then the vane-passing order V and its first harmonic 2V. The 80 blades are NOT an engine order for this blade (CADSB-857)."}]},"detail":"WHY DECLARED. This stage does not exist: its 80 blades, 11,000 rpm and 330 mm hub are declared by web/turbine-blade.html in its own words, and the vane count is exactly as much ours to declare — there was never anything to license and never anything to measure. Filing it as UNKNOWN was the lesser half of CADSB-857; printing it as a measurement would be worse. THE SELECTION RULE. Choose vane and blade counts with no low common factor, so the engine orders the two rows excite SPREAD across the Campbell diagram instead of clustering on a few multiples — a prime vane count guarantees that against any blade count which is not a multiple of it — and hold the vane count at roughly 0.5–1.0x the blade count so one stage's vane chord and loading stay sensible. 47 satisfies both: prime, gcd(47, 80) = 1, 47/80 = 0.59. WHAT READS THIS. ops/feaCase.js derives rotor.engineOrders = [1, 2, V, 2V] from the vane count and REFUSES a rotor that has none rather than substituting the blade count; demos/turbine_blade/walls.js designClass() and tools/fea/turbine_blade_qualify.js both take the number from this entry (CADSF-1349), so it cannot drift between the pack, the case and the demo.","basis":"A rotor blade is excited at EO = the upstream vane count and its harmonics, so the two row counts are chosen with no low common factor to spread those orders; the number itself is this invented demo stage's own design decision, recorded as declared rather than dressed as a measurement","sources":["nativecad-demo-stage-design-record"],"see":["turbomachinery/hp-blade-aeroderivative-scale","turbomachinery/vibration-campbell-diagram-note"],"tags":["nozzle-guide-vane","vane-count","engine-order","campbell-diagram","declared"]},{"id":"hp-blade-industrial-frame-scale","kind":"dimension","tier":1,"title":"First-stage HP rotor blade scale — industrial (heavy-duty) frame class","summary":"A heavy-duty industrial-frame turbine's first HP stage runs a larger, slower blade: span 200+ mm against a 500-900 mm hub radius, at 3,000 or 3,600 rpm synchronous speed.","applies":["turbine blade","hp turbine","industrial gas turbine","heavy-duty frame"],"value":{"min":200,"unit":"mm","note":"first-stage blade span; hub radius typically 500-900 mm"},"basis":"Industrial frame turbines run at grid-synchronous speed (3,000/3,600 rpm, 2-pole) and scale up blade size rather than rotor speed for comparable power","sources":["boyce-gas-turbine-handbook","api-616"],"tags":["turbine-blade","industrial-frame","scale","synchronous-speed"]},{"id":"blade-aspect-ratio","kind":"dimension","tier":1,"title":"HP turbine rotor blade aspect ratio (span : chord)","summary":"First-stage HP turbine rotor blade aspect ratio (span/mean chord) typically runs 1.0-2.0 — short and stubby versus a compressor blade's 2.5-4, since a hot, highly-loaded HP stage favours a thicker, stiffer aerofoil.","applies":["turbine blade","hp turbine","blade aerofoil"],"value":{"min":1,"max":2,"unit":"ratio"},"basis":"Low aspect ratio keeps the HP aerofoil thick enough to survive combined thermal and centrifugal load and to route internal cooling, at some aerodynamic cost","sources":["nasa-sp290-turbine-design","rolls-royce-jet-engine"],"tags":["turbine-blade","aspect-ratio","aerofoil"]},{"id":"blade-taper-ratio","kind":"dimension","tier":1,"title":"HP turbine rotor blade taper ratio (tip chord : root chord)","summary":"Tip chord runs 0.5-0.8x the root chord on a typical first-stage HP rotor blade — tapering the section outboard trims centrifugal (pull) stress at the root, which carries the full blade's load.","applies":["turbine blade","hp turbine","blade aerofoil"],"value":{"min":0.5,"max":0.8,"unit":"ratio"},"basis":"Centrifugal root stress scales with the mass distribution outboard of the root; tapering the tip trims that mass without giving up as much aerodynamic loading capacity as a uniform section","sources":["nasa-sp290-turbine-design","boyce-gas-turbine-handbook"],"tags":["turbine-blade","taper","aerofoil","root-stress"]},{"id":"blade-twist-angle","kind":"dimension","tier":1,"title":"HP turbine rotor blade twist, root to tip","summary":"A first-stage HP rotor blade twists 15-30 deg in stagger angle from root to tip, following a free- or controlled-vortex design that keeps flow incidence and work extraction even as blade speed rises with radius.","applies":["turbine blade","hp turbine","blade aerofoil"],"value":{"min":15,"max":30,"unit":"deg"},"basis":"Free-vortex flow design requires tangential velocity to fall as 1/radius; because blade speed instead rises with radius, the section must twist so incidence and loading stay matched hub to tip","sources":["nasa-sp290-turbine-design"],"tags":["turbine-blade","twist","stagger-angle","free-vortex"]},{"id":"le-te-radii-pct-chord","kind":"dimension","tier":1,"title":"Leading- and trailing-edge radii as a fraction of chord","summary":"A turbine aerofoil's leading-edge radius runs 2-4% of chord (blunt, to tolerate incidence swings and erosion); the trailing edge is far sharper, sized by castability rather than aerodynamics — see te-thickness-target.","applies":["turbine blade","blade aerofoil","leading edge","trailing edge"],"value":{"min":2,"max":4,"unit":"%","note":"leading-edge radius as % chord"},"basis":"A generously-rounded leading edge tolerates the incidence range a real engine sees across its map without separating; the trailing edge instead wants to be as thin as the process allows","sources":["nasa-sp290-turbine-design","rolls-royce-jet-engine"],"tags":["turbine-blade","leading-edge","trailing-edge","aerofoil"]},{"id":"te-thickness-target","kind":"dimension","tier":1,"title":"Trailing-edge thickness target, as-cast","summary":"An as-cast nickel-superalloy HP blade trailing edge is held to 0.5-0.8 mm minimum thickness — thinner and the ceramic mould does not fill before the metal freezes; verify with cad_dfm_check {process:\"investment_casting\"}.","applies":["turbine blade","trailing edge","investment casting"],"value":{"min":0.5,"max":0.8,"unit":"mm"},"check":{"process":"investment_casting","rule":"min_trailing_edge_thickness"},"basis":"Foundry practice for as-cast (not ground) nickel-superalloy trailing edges: below this range the wax edge distorts before shelling, or the last sliver of mould cavity does not fill","sources":["ici-design-guidelines","mcdp-investment-casting-guide"],"tags":["turbine-blade","trailing-edge","castability","investment-casting"]},{"id":"fir-tree-root-proportions","kind":"dimension","tier":1,"title":"Fir-tree blade-root proportions: neck width vs platform, lobe count","summary":"A fir-tree root's neck (under the platform) runs 0.35-0.5x the platform width, broadening through 2-4 pairs of serration lobes to the base — more lobes share centrifugal pull across more, smaller flanks.","applies":["turbine blade","fir-tree root","blade attachment"],"value":{"min":0.35,"max":0.5,"unit":"ratio","note":"neck width : platform width"},"basis":"The fir-tree attachment carries the whole blade's centrifugal pull in shear/bearing across its flanks; a narrower neck concentrates stress under the platform, so it is kept wide relative to the lobes below","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["fir-tree","blade-root","attachment","neck"]},{"id":"fir-tree-flank-angle","kind":"dimension","tier":1,"title":"Fir-tree serration flank angle","summary":"Fir-tree lobe flank angle (from the radial/pull direction) runs 30-45 deg — shallow enough to keep flank bearing stress moderate, steep enough the lobe does not need excessive radial length to develop it.","applies":["turbine blade","fir-tree root","blade attachment"],"value":{"min":30,"max":45,"unit":"deg"},"basis":"The flank angle sets how centrifugal pull resolves into flank bearing stress and radial engagement length; 30-45 deg is the common working range across published fir-tree and dovetail designs","sources":["boyce-gas-turbine-handbook"],"tags":["fir-tree","blade-root","flank-angle","attachment"]},{"id":"platform-thickness","kind":"dimension","tier":1,"title":"Blade platform thickness","summary":"A first-stage HP blade platform runs 2.5-4 mm thick at blade scale — thick enough to seal the gas-path annulus and carry its own bending load between adjacent blades, thin enough to limit root centrifugal mass.","applies":["turbine blade","platform","blade root"],"value":{"min":2.5,"max":4,"unit":"mm"},"basis":"The platform is a small unsupported panel spanning the gap to the next blade's platform, loaded by gas pressure and its own centrifugal field; this is the common published proportion at first-stage HP scale","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["platform","blade-root","thickness"]},{"id":"tip-clearance-targets","kind":"dimension","tier":1,"title":"HP turbine tip clearance: cold build vs hot running","summary":"A first-stage HP turbine is built with 1.0-1.5 mm cold tip clearance (~2% span) so nothing rubs on start-up, closing to a 0.3-0.5 mm hot-running target (~0.5-1% span) as casing/disc grow toward the blade.","applies":["turbine blade","tip clearance","hp turbine"],"value":{"table":[{"state":"cold build","mm":"1.0-1.5","pctSpan":"~2"},{"state":"hot running target","mm":"0.3-0.5","pctSpan":"~0.5-1"}]},"basis":"Casing, disc and blade grow thermally/centrifugally at different rates through a start; active-clearance-control relies on that differential growth (not machining) to close the running gap — 1% of span lost to clearance costs roughly 1-2% stage efficiency","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["tip-clearance","hp-turbine","active-clearance-control"]},{"id":"rotor-speed-and-g-level-aeroderivative","kind":"dimension","tier":1,"title":"Aero-derivative rotor speed and blade centrifugal g-level","summary":"At ~11,000 rpm (omega ~1,152 rad/s), a blade centre-of-mass near 360 mm radius sees centrifugal acceleration omega^2*r_cg ~48,000 g — orders of magnitude above consumer mechanical design.","applies":["turbine blade","rotor speed","centrifugal load","aero-derivative gas turbine"],"value":{"value":48000,"unit":"ratio","note":"omega^2 * r_cg, in units of standard gravity g, at approx. 11,000 rpm"},"basis":"omega^2*r_cg is the standard centrifugal-acceleration figure of merit for a rotating blade; small radius but very high speed drives a g-level far above an industrial frame's","sources":["boyce-gas-turbine-handbook"],"tags":["rotor-speed","centrifugal-load","g-level","aero-derivative"]},{"id":"rotor-speed-industrial-frame","kind":"dimension","tier":1,"title":"Industrial-frame rotor speed: grid-synchronous 3,000 / 3,600 rpm","summary":"A generator-drive industrial turbine runs at 3,000 rpm (50 Hz, 2-pole) or 3,600 rpm (60 Hz, 2-pole) — 3-4x slower than an aero-derivative core, why its first-stage blade is so much larger for comparable power.","applies":["turbine blade","rotor speed","industrial gas turbine","turbogenerator"],"value":{"table":[{"gridHz":50,"rpm":3000},{"gridHz":60,"rpm":3600}]},"basis":"A generator-drive turbine coupled directly to a 2-pole alternator must turn at the grid's synchronous speed; g-level scales as the square of that fixed speed, so industrial frames trade rotor speed for blade size","sources":["api-616","boyce-gas-turbine-handbook"],"tags":["rotor-speed","industrial-frame","synchronous-speed","generator-drive"]},{"id":"in718-properties-20-650c","kind":"material","tier":1,"title":"IN718 (Inconel 718) properties at 20 C and 650 C","summary":"Wrought/cast IN718: density 8.19 g/cm3, modulus ~200 GPa (20 C) / ~165 GPa (650 C), 0.2% yield 1035/800 MPa, UTS 1240/970 MPa (20 C/650 C) — strength drops sharply above ~650 C.","applies":["in718","inconel 718","nickel superalloy","turbine disc"],"value":{"table":[{"tempC":20,"densityGcm3":8.19,"modulusGPa":200,"yieldMPa":1035,"utsMPa":1240},{"tempC":650,"densityGcm3":8.19,"modulusGPa":165,"yieldMPa":800,"utsMPa":970}],"unit":"MPa"},"basis":"AMS 5596 minimum-property table (20 C and 649 C) from the Special Metals INCONEL 718 bulletin; used for discs/cooler stages rather than the 850 C first-stage HP blade — see in738lc-properties-20-650-850c","sources":["specialmetals-in718","donachie-superalloys"],"tags":["material","in718","superalloy","nickel-alloy","turbine-disc"]},{"id":"in738lc-properties-20-650-850c","kind":"material","tier":1,"title":"IN738LC (cast nickel superalloy) properties at 20/650/850 C","summary":"Cast IN738LC (the classic first-stage HP blade alloy): density 8.11 g/cm3, modulus ~168/148/122 GPa at 20/650/850 C; 0.2% yield ~950/850/700 MPa; UTS ~1060/970/780 MPa at the same temperatures.","applies":["in738lc","in-738lc","nickel superalloy","turbine blade","investment casting"],"value":{"table":[{"tempC":20,"densityGcm3":8.11,"modulusGPa":168,"yieldMPa":950,"utsMPa":1060},{"tempC":650,"densityGcm3":8.11,"modulusGPa":148,"yieldMPa":850,"utsMPa":970},{"tempC":850,"densityGcm3":8.11,"modulusGPa":122,"yieldMPa":700,"utsMPa":780}],"unit":"MPa"},"basis":"Handbook-typical published data for cast IN738LC, representative of the alloy class, not a certified single-heat sheet. Per-value sources, and CADSF-1350's two DISAGREEMENTS (E 122 vs 151 GPa; yield 700 vs 552 MPa), are in in738lc-properties-sourced.","sources":["in738lc-published-data","donachie-superalloys","asm-handbook-vol15"],"tags":["material","in738lc","superalloy","nickel-alloy","turbine-blade"],"see":["turbomachinery/in738lc-properties-sourced"]},{"id":"marin-endurance-factors","kind":"rule","tier":2,"title":"Marin endurance-limit factors for an as-cast aerofoil","summary":"Se_corrected = Se * k_size * k_surface * k_temperature * k_reliability. Size k = 1.24 de^-0.107 (2.79-51 mm); surface k = a Sut^b, a = 4.51 MPa, b = -0.265 (machined band, Ra 1.6-3.2 um as-cast); reliability 0.897/0.814/0.753 at 90/99/99.9 %.","applies":["fatigue","endurance limit","turbine blade","investment casting","goodman"],"value":{"table":[{"factor":"size","formula":"de = sqrt(4 A / pi) from the section area A; k = 1.24 de^-0.107 for 2.79 <= de <= 51 mm, 1.51 de^-0.157 for 51 < de <= 254 mm","source":"shigley-mechanical-engineering-design","basis":"Shigley Eq. 6-20. The equivalent diameter is taken as the solid round bar of the SAME SECTION AREA — Shigley's A_95sigma construction is defined for rounds and rectangles, not for a twisted aerofoil, and the substitution is stated rather than implied."},{"factor":"surface","formula":"k = a * Sut_MPa^b","aMPa":4.51,"b":-0.265,"surfaceClass":"machined-or-cold-drawn","source":"shigley-mechanical-engineering-design + ici-design-guidelines","basis":"Shigley Table 6-2 has no as-cast row. An investment-cast aerofoil leaves Ra 1.6-3.2 um, inside the machined band, so the machined row is used; the as-forged row (a = 272, b = -0.995) would give 0.266 at Sut 1060 MPa and is recorded here as the pessimistic alternative. Casting POROSITY, not roughness, dominates cast HCF (hoffelner-1982-in738-hcf) and no surface factor represents it."},{"factor":"temperature","formula":"k = Sut(T) / Sut(20 C)","source":"shigley-mechanical-engineering-design","basis":"Shigley Eq. 6-27 (k_d = ST/SRT). It converts a ROOM-TEMPERATURE endurance limit to temperature, so the base Se it multiplies must be the room-temperature one or the knockdown is counted twice."},{"factor":"reliability","formula":"k = 1 - 0.08 za","table90":0.897,"table99":0.814,"table999":0.753,"table9999":0.702,"source":"shigley-mechanical-engineering-design","basis":"Shigley Table 6-5, standing in for an 8 % standard deviation on the endurance limit. It is a scatter allowance on the MATERIAL, not a reliability of the part."}],"unit":"ratio"},"basis":"Shigley's Ch. 6 Marin factors, with the two substitutions an investment-cast aerofoil forces (equivalent-diameter size, machined-band surface) written down at the point of use.","sources":["shigley-mechanical-engineering-design","ici-design-guidelines","hoffelner-1982-in738-hcf"],"tags":["fatigue","marin","endurance","goodman","as-cast"]},{"id":"in738lc-properties-sourced","kind":"material","tier":2,"title":"IN738LC at temperature - per-value sources, the modulus disagreement, and the HCF UNKNOWN","summary":"The 20/650/850 C IN738LC table, a source and status per value: density 8.11 g/cm3, E 168/148/122 GPa, nu 0.30, yield 950/850/700 MPa, UTS 1060/970/780 MPa; Se UNKNOWN; plus CADSF-1350's modulus and 850 C yield disagreements.","applies":["in738lc","in-738lc","nickel superalloy","turbine blade","investment casting","fatigue"],"value":{"table":[{"tempC":20,"densityGcm3":8.11,"modulusGPa":168,"poissonRatio":0.3,"yieldMPa":950,"utsMPa":1060,"enduranceLimit10e7MPa":null,"provenance":{"densityGcm3":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","stillNotRead":"No READ source gives a density: 8.11 g/cm3 has no source anybody has read."},"modulusGPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","disputed":true,"disagreement":"DISPUTED (CADSF-1350): 151 GPa (Lee, 871 C) vs 122 GPa here - 11.3 % on frequency; 122 ships.","disagreementRef":"value.table[2].disagreements[0]","crossCheck":"NO cross-check here - Lee Table 2's 21 C modulus cell is corrupt. His slope extrapolated to 20 C gives 197 GPa vs 168 here: ARITHMETIC PERFORMED HERE, not published."},"poissonRatio":{"source":"lee-2014-in738lc-tmf","status":"published","basis":"READ 2026-09-11: Lee 2014 Table 2 gives nu 0.28/0.30/0.29/0.30 at 21/760/871/982 C.","urlActuallyFetched":"https://www.academia.edu/36055330","readOn":"2026-09-11"},"yieldMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"The one strength value here CONFIRMED against a source actually read: Lee 2014 Table 2 (READ 2026-09-11) prints 0.2 % yield = 950 MPa at 21 C - exact agreement. nickel-institute-497 is still unread.","crossCheck":"Lee: 950 MPa at 21 C (exact). EOS: 1122/1044 MPa at 25 C (AM+HIP).","readOn":"2026-09-11","urlActuallyFetched":"https://www.academia.edu/36055330"},"utsMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"EOS: Rm 1265/1412 MPa at 25 C (AM+HIP) vs 1060 here - higher, finer grain; no cast UTS read."},"enduranceLimit10e7MPa":{"source":"schneider-1982-in738lc-hcf + hoffelner-1982-in738-hcf","status":"unknown","basis":"UNKNOWN - Schneider 1982 / Hoffelner 1982 IN738LC HCF data: paywalled, NOT read; no fraction-of-Sut substitute used."}}},{"tempC":650,"densityGcm3":8.11,"modulusGPa":148,"poissonRatio":0.3,"yieldMPa":850,"utsMPa":970,"enduranceLimit10e7MPa":null,"provenance":{"densityGcm3":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","stillNotRead":"No READ source gives a density: 8.11 g/cm3 has no source anybody has read."},"modulusGPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"Lee (READ 2026-09-11) measures 157 GPa at 760 C; extrapolated back, 162.9 GPa vs 148 here - 10.1 % low = 4.9 % on frequency.","disputed":true,"disagreement":"DISPUTED (CADSF-1350): 151 GPa (Lee, 871 C) vs 122 GPa here - 11.3 % on frequency; 122 ships.","disagreementRef":"value.table[2].disagreements[0]"},"poissonRatio":{"source":"lee-2014-in738lc-tmf","status":"published","basis":"READ 2026-09-11: Lee 2014 Table 2 gives nu 0.28/0.30/0.29/0.30 at 21/760/871/982 C.","urlActuallyFetched":"https://www.academia.edu/36055330","readOn":"2026-09-11"},"yieldMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"Lee: 793 MPa at 760 C; extrap. to 650 C = 1032 MPa, ABOVE this pack - curves cross between 650/850 C."},"utsMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"No UTS read at 650 C (Lee none; EOS only 25/850 C); 970 MPa unchecked."},"enduranceLimit10e7MPa":{"source":"schneider-1982-in738lc-hcf + hoffelner-1982-in738-hcf","status":"unknown","basis":"UNKNOWN - Schneider 1982 / Hoffelner 1982 IN738LC HCF data: paywalled, NOT read; no fraction-of-Sut substitute used."}}},{"tempC":850,"densityGcm3":8.11,"modulusGPa":122,"poissonRatio":0.3,"yieldMPa":700,"utsMPa":780,"enduranceLimit10e7MPa":null,"provenance":{"densityGcm3":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","stillNotRead":"No READ source gives a density: 8.11 g/cm3 has no source anybody has read."},"modulusGPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"Lee (READ 2026-09-11) gives 151 GPa at 871 C vs 122 GPa here - the 24 % gap this ticket was filed over; 152.1 GPa interpolated to 850 C.","disputed":true,"disagreement":"DISPUTED (CADSF-1350): 151 GPa (Lee, 871 C) vs 122 GPa here - 11.3 % on frequency; 122 ships.","disagreementRef":"value.table[2].disagreements[0]"},"poissonRatio":{"source":"lee-2014-in738lc-tmf","status":"published","basis":"READ 2026-09-11: Lee 2014 Table 2 gives nu 0.28/0.30/0.29/0.30 at 21/760/871/982 C.","urlActuallyFetched":"https://www.academia.edu/36055330","readOn":"2026-09-11"},"yieldMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","disputed":true,"disagreement":"DISPUTED (CADSF-1350), unsafe direction: 552/482/477 MPa (Lee/EOS) vs 700 MPa here - 17.1 % high; Langer factor is linear in yield. 700 ships.","disagreementRef":"value.table[2].disagreements[1]","crossCheck":"Lee 552 MPa at 871 C (597.6 interp. to 850 C) and EOS 482/477 MPa at 850 C, both READ 2026-09-11, vs 700 MPa here."},"utsMPa":{"source":"in738lc-published-data + donachie-superalloys","status":"published","basis":"NOT READ from a primary source; handbook-typical.","crossCheck":"EOS: Rm 694/720 MPa at 850 C (AM+HIP) vs 780 here, 8.3-12.4 % higher - cross-check, not a disagreement."},"enduranceLimit10e7MPa":{"source":"schneider-1982-in738lc-hcf + hoffelner-1982-in738-hcf","status":"unknown","basis":"UNKNOWN - Schneider 1982 / Hoffelner 1982 IN738LC HCF data: paywalled, NOT read; no fraction-of-Sut substitute used."}},"disagreements":[{"property":"modulusGPa","severity":"11.3 % on every natural frequency; conservative in sign","packValue":"168 / 148 / 122 GPa at 20 / 650 / 850 C","competingValue":"157 / 151 / 141 GPa at 760 / 871 / 982 C (Lee 2014 Table 2)","competingSource":"lee-2014-in738lc-tmf","competingSourceWasRead":"YES (2026-09-11)","packValueSourceWasRead":"NO - handbook-typical (nickel-institute-497 unread).","sizeOfTheGap":"151/122 = 1.2377 (23.8 % at 871 C; 24.7 % interpolated to 850 C on Lee's slope).","consequenceOnFrequency":"DERIVED (tools/fea/modulus_band.js): f scales as sqrt(E/rho), sqrt(151/122) = 1.1125 - every frequency and Campbell crossing is 11.3 % higher on Lee's modulus (4.9 % at 650 C), larger than any crossing margin quoted in this chain.","whyTheyDisagree":"NOT RESOLVED (full analysis: docs/PLAN_2026-09_BLADE_QUAL.md#cadsf-1350). Static vs dynamic modulus: right sign, too small. Product form needs ~10 % porosity. This pack's own 650->850 C slope is -0.130 GPa/C, 2.4 times Lee's measured -0.0541 - a suspicion, not a correction.","whatShips":"122 GPa at 850 C (168 / 148 at 20 / 650 C), UNCHANGED.","whyThatShips":"(1) Every committed modal and Campbell result used 168/148/122 GPa; Lee's curve moves every quoted frequency ~11 % and invalidates results nobody re-ran. (2) A lower E places crossings EARLIER in the run-up - the pessimistic choice. (3) ADR-13: Lee's table is one FE paper's input, not a campaign, so promoting it would buy no provenance.","whatWouldCloseIt":"nickel-institute-497's E-vs-T table (unreachable), or a measured E(T) on this casting.","ticket":"CADSF-1350"},{"property":"yieldMPa","severity":"17.1 % onto the only margin this demo quotes; NOT conservative - unsafe","packValue":"700 MPa at 850 C","competingValue":"552 MPa at 871 C (Lee 2014 Table 2); 482 / 477 MPa at 850 C (EOS, AM+HIP)","competingSource":"lee-2014-in738lc-tmf + eos-nickelalloy-in738-mds","competingSourceWasRead":"YES (2026-09-11)","packValueSourceWasRead":"NO - same as the modulus.","sizeOfTheGap":"700/552 = 1.268 (26.8 % above Lee at 871 C); 597.6 MPa interpolated to 850 C = 17.1 % high. No gap at 20 C (both 950 MPa) - curves cross.","consequenceOnFrequency":"None - hits the MARGIN, not frequency: Se is UNKNOWN, so the quoted factor is the Langer yield factor, LINEAR in yield - ~17 % optimistic, unsafe (unlike the modulus).","whyTheyDisagree":"NOT RESOLVED - likelier a transcription/temperature-shift error than a real material difference (product forms differ, so unproven). Full analysis: docs/PLAN_2026-09_BLADE_QUAL.md#cadsf-1350.","whatShips":"700 MPa at 850 C, UNCHANGED.","whyThatShips":"Same ADR-13 reason as the modulus; every committed result used 700 MPa. Disclosed harder - this direction is optimistic.","whatWouldCloseIt":"nickel-institute-497's tensile table (unreachable), or Balikci et al. (2000) cast IN738LC data (landing page only, paywalled) - docs/PLAN_2026-09_BLADE_QUAL.md#cadsf-1350.","ticket":"CADSF-1350"}]}],"unit":"MPa","note":"enduranceLimit10e7MPa is null at every temperature: UNKNOWN, see provenance. Modulus and 850 C yield are DISPUTED - see detail and value.table[2].disagreements."},"basis":"One row per temperature; provenance.<field> carries {source, status, basis} for that field alone. status is \"published\" or \"unknown\" - never \"estimated\" (ADR-13).","sources":["in738lc-published-data","donachie-superalloys","lee-2014-in738lc-tmf","schneider-1982-in738lc-hcf","hoffelner-1982-in738-hcf","nickel-institute-497","eos-nickelalloy-in738-mds"],"tags":["material","in738lc","superalloy","fatigue","turbine-blade","provenance"],"detail":"CADSF-1350. READ 2026-09-11: Lee 2014 Table 2 and the EOS IN738 sheet v011/2024 (AM+HIP, cross-check only). NOT READ: nickel-institute-497, egress-refused by five routes - so DENSITY has no source anybody has read, and no cast UTS was read. Two DISAGREEMENTS at value.table[2].disagreements: E 122 vs Lee's 151 GPa (24 % = 11.3 % on every frequency, conservative); yield 700 vs 552/482 MPa (17.1 % high, OPTIMISTIC). Both ship UNCHANGED. Narrative: docs/PLAN_2026-09_BLADE_QUAL.md."},{"id":"min-castable-section-investment","kind":"rule","tier":1,"title":"Minimum castable section thickness (investment casting)","summary":"Nickel-superalloy investment castings at blade scale hold a minimum section thickness of ~1.0-1.5 mm — thinner and the ceramic mould misruns or cold-shuts before filling; check with cad_dfm_check {process:\"investment_casting\"}.","applies":["investment casting","turbine blade","castability"],"value":{"min":1,"max":1.5,"unit":"mm"},"check":{"process":"investment_casting","rule":"min_section"},"basis":"Investment-casting design guides publish this as the practical floor for a nickel-superalloy section at small-to-medium (blade-class) part scale; heavier industrial-frame sections tolerate more","sources":["ici-design-guidelines","mcdp-investment-casting-guide","beeley-smart-investment-casting"],"tags":["castability","min-section","investment-casting","rule"]},{"id":"min-trailing-edge-thickness-rule","kind":"rule","tier":2,"title":"min_trailing_edge_thickness — the thin-edge castability gate","summary":"cad_dfm_check {process:\"investment_casting\"} runs a thin-edge detector: any edge whose two adjacent faces meet at under a approx. 30 deg dihedral, or any face pair reading thin at their shared boundary, is reported by edge id plus both face ids against a 0.6 mm default floor.","applies":["investment casting","trailing edge","dfm-check"],"detail":"The detector runs two tests over every pair of topologically adjacent mesh faces. First, a geometric test: if the two faces' outward normals are closer to antiparallel than -cos(params.trailingEdgeDihedralDeg) (default 30 deg), the pair is a knife-edge dihedral — a wedge that comes to a mathematically sharp line has zero thickness there by construction, so it is reported at value 0 regardless of how a coarse mesh happens to sample it. Second, a measurement test: for a trailing edge modelled with its own small flat or radiused cap (not a mathematical point), the pair is flagged when the existing opposed-ray wall probe already reads below the limit at that boundary. Either path's finding carries entityRefs [edge, face, face] so a reviewer (or a fillet/thicken op) can act on the exact edge.","check":{"process":"investment_casting","rule":"min_trailing_edge_thickness"},"basis":"A cast (not ground) nickel-superalloy trailing edge thinner than roughly 0.5-0.8 mm risks the wax pattern distorting before shelling, or the alloy freezing before it fills the last sliver of mould","sources":["ici-design-guidelines","mcdp-investment-casting-guide"],"tags":["trailing-edge","dfm-check","investment-casting","edge-id"]},{"id":"min-fillet-radius-investment","kind":"rule","tier":2,"title":"min_fillet_radius — unblended internal edges on a casting pattern","summary":"cad_dfm_check {process:\"investment_casting\"} flags any internal (concave) edge left sharp with no blend face at all (reported by edge id, radius 0) plus any existing fillet under the 0.5 mm default floor (reported by face id) — see params.minFilletMm.","applies":["investment casting","fillet","dfm-check"],"check":{"process":"investment_casting","rule":"min_fillet_radius"},"basis":"Foundry practice keeps every internal junction on a casting pattern radiused rather than sharp: an unblended internal corner concentrates shrinkage stress and promotes hot tearing on top of the fatigue stress-riser it is in service","sources":["ici-design-guidelines","beeley-smart-investment-casting"],"tags":["fillet","dfm-check","investment-casting","internal-corner"]},{"id":"max-section-ratio-investment","kind":"rule","tier":2,"title":"max_section_ratio — thickest : thinnest sampled section","summary":"cad_dfm_check {process:\"investment_casting\"} caps the ratio between a body's thickest and thinnest sampled section at 6:1 by default (params.maxSectionRatio), naming both faces — an abrupt change starves the thin side of feed metal during solidification.","applies":["investment casting","section ratio","dfm-check"],"value":{"max":6,"unit":"ratio"},"check":{"process":"investment_casting","rule":"max_section_ratio"},"basis":"Investment-casting guides cap the thickest:thinnest adjoining-section ratio near 3:1 for a conservative shape and up to about 6:1 where the transition is gradual; 6:1 is the loose, root-to-tip aerofoil-class end of the range","sources":["ici-design-guidelines","mcdp-investment-casting-guide"],"tags":["section-ratio","dfm-check","investment-casting","shrink-porosity"]},{"id":"disc-burst-margin","kind":"rule","tier":2,"title":"Turbine disc burst-margin practice","summary":"Design practice holds a turbine disc's burst speed to at least 1.3x its design (redline) speed on a rim-average tangential-stress basis — the disc must survive an over-speed transient (e.g. a shed blade) without fragmenting.","applies":["turbine disc","burst margin","rotor integrity"],"value":{"min":1.3,"unit":"ratio"},"basis":"Rotor-integrity practice: burst speed (average-stress / rim-load criterion) must clear design operating speed by this margin so a credible over-speed event does not fragment the disc","sources":["boyce-gas-turbine-handbook"],"tags":["disc","burst-margin","rotor-integrity","overspeed"]},{"id":"creep-life-larson-miller","kind":"rule","tier":2,"title":"Larson-Miller parameter for creep-rupture life","summary":"LMP = T*(C + log10(t_r)), T in Rankine and t_r the rupture life in hours, collapses a superalloy's stress-rupture data from many temperatures onto one master curve; C approx. 20 is the common nickel-superalloy constant.","applies":["creep","stress rupture","superalloy","turbine blade"],"value":{"value":20,"unit":"ratio","note":"the Larson-Miller constant C, typical for nickel superalloys"},"basis":"The standard method for extrapolating short high-temperature stress-rupture tests to the multi-thousand-hour life a blade needs, without running every test that long","sources":["larson-miller-1952","donachie-superalloys"],"tags":["creep","larson-miller","stress-rupture","life-prediction"]},{"id":"core-support-investment-casting","kind":"process","tier":2,"title":"Ceramic core support for cast internal cooling passages","summary":"A cored (hollow, internally cooled) blade needs its ceramic core pinned by at least 2 support points per approx. 50 mm of unsupported core length, or the core shifts under the pour and produces a wall thin on one side, thick on the other.","applies":["investment casting","cored blade","cooling passage"],"value":{"min":2,"unit":"count","note":"per approx. 50 mm of unsupported ceramic core length"},"basis":"The ceramic core defining internal cooling passages is a fragile, unsupported beam inside the wax pattern until the metal solidifies; core shift is one of the most common investment-casting yield losses on a cooled aerofoil","sources":["ici-design-guidelines","asm-handbook-vol15"],"tags":["core-support","cored-blade","cooling-passage","investment-casting"]},{"id":"lost-wax-process-stages","kind":"process","tier":2,"title":"Investment (lost-wax) casting: the process stages","summary":"Lost-wax casting runs 5 stages: wax pattern injection (into a rigid die), ceramic shell build-up (repeated dip/stucco/dry cycles), wax dewax (steam autoclave or flash-fire), shell fire and pour, then shell knockout and cutoff — each stage imposes its own geometry limits.","applies":["investment casting","lost-wax casting","process"],"value":{"value":5,"unit":"count","note":"the number of principal process stages"},"detail":"Wax pattern injection needs draft on the die (not the final casting) and a wall the wax itself can fill and hold dimension in. Ceramic shell build-up is what makes the trailing edge and fillet floors in this pack meaningful, since the shell (not a rigid tool) is the actual mould. Dewax must not distort the thin wax edges before the shell has cured. The pour must reach every cored passage before the alloy freezes, which is what drives the min-section and max-section-ratio floors. Knockout and cutoff (removing the shell and the gating/runner system) is a finishing operation this pack does not model.","basis":"Standard investment-casting process sequence, so a modeller understands which stage a given geometric floor (draft, section, TE thickness, fillet) actually constrains","sources":["beeley-smart-investment-casting","ici-design-guidelines"],"tags":["lost-wax","process","ceramic-shell","investment-casting"]},{"id":"hot-isostatic-pressing","kind":"process","tier":2,"title":"Hot isostatic pressing (HIP) closes internal casting porosity","summary":"HIP post-processes a superalloy investment casting at roughly 1120-1200 C and 100-200 MPa isostatic argon pressure for 2-4 hours, closing internal (non-surface-connected) shrinkage porosity that would otherwise seed fatigue cracks.","applies":["investment casting","hip","porosity","turbine blade"],"value":{"min":100,"max":200,"unit":"MPa","note":"typical HIP isostatic pressure; temperature roughly 1120-1200 C for 2-4 h"},"basis":"HIP is standard practice for flight- and power-critical cast superalloy parts: internal shrinkage porosity cannot always be avoided at the pattern stage, and closing it recovers most of a fully-dense part's fatigue life","sources":["asm-handbook-vol15","donachie-superalloys"],"tags":["hip","porosity","post-processing","investment-casting"]},{"id":"wax-pattern-die-draft","kind":"rule","tier":2,"title":"Draft on the wax injection die (not the finished casting)","summary":"The rigid metal die that injection-moulds the wax pattern wants 0.5-1 deg draft per side to eject the wax cleanly — a constraint on the die design, not on the finished casting, whose ceramic shell is broken away rather than drawn.","applies":["investment casting","wax pattern","draft"],"value":{"min":0.5,"max":1,"unit":"deg"},"basis":"cad_dfm_check {process:\"investment_casting\"} marks min_draft_angle not_applicable to the casting itself (the shell is broken away, not drawn); this records the real, separate draft constraint on the wax die that a pattern-tooling shop still needs","sources":["ici-design-guidelines","beeley-smart-investment-casting"],"tags":["draft","wax-pattern","tooling","investment-casting"]},{"id":"tolerance-chain-tip-clearance","kind":"tolerance","tier":2,"title":"Tolerance-chain contributors to HP turbine tip clearance","summary":"Running tip clearance stacks 5 contributors: casing bore radius, disc rim radius, blade height, and the thermal growth of the casing and the disc/blade assembly — each typically +/-0.1 to +/-0.6 mm, summing to the cold-build allowance tip-clearance-targets budgets for.","applies":["tip clearance","tolerance stack","hp turbine"],"value":{"table":[{"contributor":"casing bore radius","typicalPlusMinusMm":0.1},{"contributor":"disc rim radius (machined, cold)","typicalPlusMinusMm":0.08},{"contributor":"blade height (cast + machined)","typicalPlusMinusMm":0.15},{"contributor":"casing thermal growth","typicalPlusMinusMm":0.3},{"contributor":"disc + blade thermal/centrifugal growth","typicalPlusMinusMm":0.6}]},"basis":"A running tip-clearance budget is a tolerance chain like any other assembly stack, but two of its five terms are thermal (casing growth, disc/blade growth) rather than purely dimensional","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["tolerance-stack","tip-clearance","thermal-growth","hp-turbine"]},{"id":"thermal-growth-casing","kind":"dimension","tier":2,"title":"HP turbine casing radial thermal growth, cold to hot","summary":"The HP turbine casing grows 0.5-1.0 mm radially from cold build to hot steady-state running — a thin-walled casing at gas-path temperature responding faster than the heavier disc it surrounds, which is most of why cold clearance can be built tight.","applies":["thermal growth","hp turbine casing","tip clearance"],"value":{"min":0.5,"max":1,"unit":"mm"},"basis":"A thin casing has low thermal mass and heats quickly, growing radially by alpha*r*deltaT; active-clearance-control systems manage this term with cooling air because it responds fastest of the three growth contributors","sources":["rolls-royce-jet-engine","boyce-gas-turbine-handbook"],"tags":["thermal-growth","casing","tip-clearance"]},{"id":"thermal-growth-disc-rim","kind":"dimension","tier":2,"title":"HP turbine disc rim growth, thermal plus centrifugal","summary":"The disc rim grows 1.0-2.0 mm radially from cold-static to hot-running-speed, combining thermal expansion (a slower-heating, heavier component than the casing) with centrifugal stretch at design rotor speed.","applies":["thermal growth","turbine disc","tip clearance","centrifugal growth"],"value":{"min":1,"max":2,"unit":"mm"},"basis":"The disc is far more massive than the casing and heats more slowly, but its growth also includes the elastic centrifugal stretch of a spinning rotor at speed; the two effects are usually budgeted together as one running-growth allowance","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["thermal-growth","disc","centrifugal-growth","tip-clearance"]},{"id":"thermal-growth-blade","kind":"dimension","tier":2,"title":"HP turbine blade radial (centrifugal) growth under load","summary":"A first-stage HP blade stretches 0.1-0.3 mm radially under its own centrifugal load at design speed — small next to the disc's own growth, but the growth term closest to the tip, so still counted in the tip-clearance chain.","applies":["thermal growth","turbine blade","tip clearance","centrifugal growth"],"value":{"min":0.1,"max":0.3,"unit":"mm"},"basis":"The blade is its own elastic body under centrifugal load (self-weight pulling against the fir-tree root) and stretches measurably at design speed even though it is short compared to the disc","sources":["boyce-gas-turbine-handbook"],"tags":["thermal-growth","blade","centrifugal-growth","tip-clearance"]},{"id":"casing-bore-tolerance","kind":"tolerance","tier":2,"title":"HP turbine casing bore machining tolerance","summary":"A machined HP turbine casing bore is typically held to +/-0.05 to +/-0.15 mm on radius — a precision-bored ring, since its radius is one of the direct terms in the tip-clearance tolerance chain.","applies":["casing","tolerance","machining","tip clearance"],"value":{"min":0.05,"max":0.15,"unit":"mm"},"basis":"The casing bore directly sets one side of the tip-clearance gap, so it is held to a precision-machining tolerance rather than a commercial one — see tolerance-chain-tip-clearance","sources":["boyce-gas-turbine-handbook"],"tags":["tolerance","casing","bore","tip-clearance"]},{"id":"disc-rim-radius-tolerance","kind":"tolerance","tier":2,"title":"Turbine disc rim radius machining tolerance","summary":"A machined turbine disc rim (the fir-tree slot broach diameter) is held to +/-0.05 to +/-0.10 mm on radius — tighter than a typical structural bore, since it sets the blade's effective radius and therefore its centrifugal load and tip position.","applies":["turbine disc","tolerance","machining","fir-tree slot"],"value":{"min":0.05,"max":0.1,"unit":"mm"},"basis":"The disc rim radius fixes where the blade root seats and therefore both its centrifugal moment arm and its contribution to tip-clearance stack-up, so it is machined tighter than a non-critical structural bore","sources":["boyce-gas-turbine-handbook"],"tags":["tolerance","turbine-disc","rim-radius","fir-tree"]},{"id":"blade-height-tolerance","kind":"tolerance","tier":2,"title":"Cast + machined blade height tolerance","summary":"A first-stage HP blade's overall height (fir-tree base to tip) is held to +/-0.10 to +/-0.20 mm after casting and root/tip machining — the fourth of the five tip-clearance tolerance-chain contributors.","applies":["turbine blade","tolerance","blade height","tip clearance"],"value":{"min":0.1,"max":0.2,"unit":"mm"},"basis":"Blade height combines as-cast dimensional variation with the root and tip machining that follows casting; one of the five terms tolerance-chain-tip-clearance sums to size the cold-build clearance","sources":["boyce-gas-turbine-handbook","ici-design-guidelines"],"tags":["tolerance","turbine-blade","blade-height","tip-clearance"]},{"id":"fir-tree-lobe-count-and-skew","kind":"dimension","tier":2,"title":"Fir-tree lobe count and root skew angle","summary":"A first-stage HP fir-tree root commonly carries 2-4 pairs of serration lobes, cut with a 0-15 deg skew (broach angle relative to the rotor axis) to help retain the blade axially in the disc slot.","applies":["fir-tree root","blade attachment","turbine disc"],"value":{"table":[{"param":"lobe pairs","min":2,"max":4},{"param":"skew angle deg","min":0,"max":15}]},"basis":"Lobe count trades broaching complexity against how many flanks share the centrifugal load; a small skew angle is common for axial retention, on top of a separate positive lock (tab or pin) most designs still add","sources":["boyce-gas-turbine-handbook"],"tags":["fir-tree","lobe-count","skew","blade-attachment"]},{"id":"ds-sx-superalloys","kind":"material","tier":2,"title":"Directionally-solidified and single-crystal superalloys","summary":"Above IN738LC's practical range, directionally-solidified (DS, e.g. MAR-M247 DS) and single-crystal (SX, e.g. CMSX-4) superalloys remove transverse grain boundaries entirely, buying roughly 30-60 C of extra creep-rupture capability at the same stress and life.","applies":["single crystal","directionally solidified","superalloy","turbine blade"],"value":{"min":30,"max":60,"unit":"C","note":"typical creep-rupture temperature capability gain over an equiax-cast alloy at equal stress and life"},"basis":"Grain boundaries transverse to the centrifugal load are where creep cavitation nucleates first; DS (columnar grains along the blade axis) and SX (no grain boundaries) castings push the creep-life-limited temperature up substantially, at higher cost and process risk than equiax investment casting","sources":["donachie-superalloys","asm-handbook-vol15"],"tags":["material","single-crystal","directionally-solidified","superalloy"]},{"id":"fpi-inspection-test","kind":"test","tier":2,"title":"Fluorescent penetrant inspection (FPI) of castings","summary":"Every investment-cast turbine blade is 100% fluorescent-penetrant inspected for surface-breaking defects (cracks, cold shuts, porosity) under UV-A light, typically at a minimum 1,000 uW/cm2 illumination, before it proceeds to machining.","applies":["investment casting","inspection","turbine blade","nde"],"value":{"min":1000,"unit":"ratio","note":"minimum UV-A illumination, uW/cm2, a common inspection-booth specification"},"basis":"FPI is the standard, near-universal 100% surface inspection for cast superalloy aerofoils: penetrant dye wicks into surface-breaking flaws invisible to the naked eye and fluoresces under UV, catching what min_section/min_trailing_edge_thickness/min_fillet_radius design out before they form","sources":["asm-handbook-vol15"],"tags":["test","fpi","inspection","nde","investment-casting"]},{"id":"ct-porosity-inspection-test","kind":"test","tier":2,"title":"X-ray CT internal-porosity inspection","summary":"A cored (hollow) turbine blade is X-ray CT (or, historically, film radiography) inspected for internal shrinkage porosity and ceramic-core remnants, typically to a 1-2% of wall-thickness defect-size acceptance criterion.","applies":["investment casting","inspection","cored blade","nde"],"value":{"min":1,"max":2,"unit":"%","note":"typical acceptable internal-defect size, as a fraction of local wall thickness"},"basis":"FPI only sees the surface; a cored blade's internal cooling passages and surrounding wall can only be verified radiographically, which is where core-shift, HIP-uncured porosity and residual core material are actually caught","sources":["asm-handbook-vol15"],"tags":["test","ct-scan","porosity","nde","cored-blade"]},{"id":"spin-pit-overspeed-test","kind":"test","tier":2,"title":"Spin-pit overspeed proof test","summary":"A production turbine disc (and, separately, a blade/disc assembly) is proof-spun to 115-120% of design speed in a containment spin pit before certification — a direct proof of the disc-burst-margin practice this pack also records.","applies":["turbine disc","test","overspeed","rotor integrity"],"value":{"min":115,"max":120,"unit":"%","note":"proof-spin speed, as a percentage of design (redline) speed"},"basis":"A spin-pit overspeed test is the direct mechanical proof that a disc (and its blade attachment) survives beyond its worst credible over-speed transient without yielding or cracking — complementary to the analytical burst-margin practice","sources":["boyce-gas-turbine-handbook"],"tags":["test","spin-pit","overspeed","rotor-integrity","turbine-disc"]},{"id":"vibration-campbell-diagram-note","kind":"note","tier":2,"title":"Campbell diagram: keeping blade natural frequencies clear of engine orders","summary":"A blade's natural bending and torsion frequencies are plotted against rotor speed on a Campbell diagram, alongside lines for each excitation \"engine order\" (1x, 2x... nozzle-count x rotor speed); a design keeps every crossing at least 10-15% away from the running speed range.","applies":["turbine blade","vibration","campbell diagram","resonance"],"basis":"A blade whose natural frequency crosses an engine-order excitation line inside the running speed range resonates in service; the Campbell diagram is the standard tool for verifying no such crossing falls where the engine actually operates, with a published margin rather than an exact-zero clearance","sources":["boyce-gas-turbine-handbook","rolls-royce-jet-engine"],"tags":["vibration","campbell-diagram","resonance","engine-order"]},{"id":"aero-derivative-vs-industrial-frame-note","kind":"note","tier":2,"title":"Why an aero-derivative core and an industrial frame size the same job so differently","summary":"For comparable shaft power, an aero-derivative core uses a small, light, very-high-speed spool (330 mm hub, 60 mm span, 11,000 rpm); a heavy-duty industrial frame instead uses a large, slow rotor (500-900 mm hub, 3,000/3,600 rpm).","applies":["aero-derivative gas turbine","industrial gas turbine","turbogenerator"],"basis":"An aero-derivative core is a de-rated aircraft engine inheriting its weight-minimised, high-speed architecture; a heavy-duty frame is purpose-built for stationary power, trading size/weight for lower rotor speed and g-loading","sources":["boyce-gas-turbine-handbook","api-616"],"tags":["aero-derivative","industrial-frame","comparison","turbogenerator"]},{"id":"recipe-fir-tree-root-profile","kind":"recipe","tier":2,"applies":["fir-tree root","turbine blade"],"tags":["recipe","fir-tree","blade-root"],"title":"Recipe: fir-tree blade-root profile (single-lobe, extruded)","summary":"Build a simplified single-lobe fir-tree root as one extruded closed profile: a 20mm-wide base, a lobe flaring to 26mm, then a 10mm-wide parallel neck rising to the platform, 25mm deep.","basis":"Combines fir-tree-root-proportions and fir-tree-flank-angle into one buildable root cross-section — a single lobe pair rather than the 2-4 a production root carries, simple enough for the kernel to build as one closed polygon","sources":["boyce-gas-turbine-handbook"],"recipe":{"prompt":"Model a simplified single-lobe fir-tree blade-root profile, 25mm deep","steps":[{"tool":"cad_extrude_profile","args":{"depth":25,"outer":[[10,0],[13,6],[5,9],[5,18],[-5,18],[-5,9],[-13,6],[-10,0]]},"note":"base (20mm wide) up through one serration lobe (flares to 26mm) to a 10mm-wide parallel neck"}],"expect":{"volume":7050,"faceCount":10,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}},{"id":"recipe-platform-shank-block","kind":"recipe","tier":2,"applies":["platform","shank","turbine blade"],"tags":["recipe","platform","shank"],"title":"Recipe: blade platform + shank as one stepped block","summary":"Build a blade platform-and-shank as one stepped extrusion: a 15x25mm shank pedestal 15mm tall, capped by a 40x25mm platform 4mm thick — a top-hat cross-section in one profile.","basis":"Combines platform-thickness with a representative shank footprint into one buildable stepped block — a real platform and shank are one continuous casting, modelled here as one extrude rather than two bodies joined by a boolean","sources":["boyce-gas-turbine-handbook"],"recipe":{"prompt":"Model a blade platform and shank as one stepped block, platform 40mm wide and 4mm thick over a 15mm shank","steps":[{"tool":"cad_extrude_profile","args":{"depth":25,"outer":[[-7.5,0],[7.5,0],[7.5,15],[20,15],[20,19],[-20,19],[-20,15],[-7.5,15]]},"note":"top-hat profile: 15mm-wide, 15mm-tall shank under a 40mm-wide, 4mm-thick platform"}],"expect":{"volume":9625,"faceCount":10,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}},{"id":"recipe-disc-sector-rim-slot","kind":"recipe","tier":2,"applies":["turbine disc","fir-tree slot","rim slot"],"tags":["recipe","turbine-disc","rim-slot"],"title":"Recipe: turbine disc sector with a rim slot","summary":"Build a 20-degree wedge of a turbine disc rim (radius 300-340mm, 20mm thick) with a simplified rectangular rim slot cut into it, as one extruded annular-sector profile with a hole.","basis":"Demonstrates a disc sector (the rim portion associated with one or a few blades) as one extrude-with-hole call — a simplified rectangular pocket standing in for the fir-tree broach slot a real disc rim carries per blade","sources":["boyce-gas-turbine-handbook"],"recipe":{"prompt":"Model a 20-degree sector of a turbine disc rim, 300 to 340mm radius, 20mm thick, with a rectangular rim slot","steps":[{"tool":"cad_extrude_profile","args":{"depth":20,"outer":[[295.4423259036624,-52.0944533000791],[334.8346360241507,-59.04038040675631],[338.7061973511935,-29.632952534203778],[340,0],[338.7061973511935,29.632952534203778],[334.8346360241507,59.04038040675631],[295.4423259036624,52.0944533000791],[298.85840942752367,26.14672282429745],[300,0],[298.85840942752367,-26.14672282429745]],"holes":[[[310,-5],[310,5],[330,5],[330,-5]]]},"note":"annular sector from r=300 to r=340mm over a 20deg arc (5-point arc approximation each side), with a 20x10x20mm rim-slot pocket"}],"expect":{"volume":85247.48,"faceCount":16,"watertight":true,"note":"measured 2026-09-19: agrees with the kernel on the CADSF-1630 corpus sweep — volume inside the 0.5% band and faceCount exact"}}}]}