Orrery

Capsule entry aerodynamics — sourced reference ​

Library reference for the descent/entry calibration (ADR-088, descent-physics.ts, static/data/descent-profiles/*.json). Per-capsule entry aerodynamic parameters with sources, plus the flown peak-g figures used to validate the model. When a value here is pulled from an external document, its link is in the Source library below — add to that list whenever you source a new figure.

Convention: L/D = hypersonic trim lift-to-drag. BC = ballistic coefficient m/(Cd·A) (kg·m⁻²) — lower = more drag area = gentler entry. Peak-g = felt deceleration on a nominal guided (lifting) entry unless noted; ballistic-mode g in parentheses.

Crewed re-entry capsules ​

CapsuleL/DBase Ø (m)BC (kg·m⁻²)Flown peak-g (LEO)Flown peak-g (lunar)Sources
Apollo CM0.303.91313.5 (sourced)~3.3 g (Apollo 7)~6.5–8 g (skip)NASA aero, FAA/NASA, ASME
Soyuz DM0.302.17~530 (derived)3–4 g~8 gprokosmos (RU), kaketoustroeno (RU)
Shenzhou RV≥0.202.52~440 (derived)≤4 g (bank-steered, ~20° trim)(skip design)Tencent explainer (CN), jdse skip-entry (CN)
Crew Dragon0.183.66~500 (derived)~4 g—Georgia Tech
Gemini RM0.192.28~330 (derived)~5–8 g—DTIC AD0856691
Mercury (orbital)0 (ballistic)1.89—~7.8 g—FAA/NASA
Mercury (suborbital)0 (ballistic)1.89—~11 g (Redstone hop)—FAA/NASA
Vostok / Voskhod0 (ballistic)2.30—~8 g—FAA/NASA
MSL / Curiosity (Mars)0.244.5~140 (Cd·A 24)—~12 g (Mars entry)MSL guidance

Notes:

  • Apollo CM BC 313.5 kg·m⁻² is directly sourced (NASA aero data, ref area 12.0 m², 3.91 m base → Cd·A 17.7, Cd ≈ 1.47). This calibrates the blunt-body Cd used to derive the others' Cd·A from their published base diameters — those BCs are marked "derived" (model estimates).
  • L/D is directly sourced for most lifting capsules (see per-capsule links). Apollo & Soyuz share the 0.3 "offset-CG / headlight" value; Dragon is lowest at 0.18 (12° trim); Gemini 0.19; Shenzhou ≥0.2; MSL/Curiosity 0.24. Exceptions (MSL-class estimates, marked in estimatedFields): Perseverance + Tianwen-1 reuse the MSL aeroshell so we take L/D 0.24, but a mission-specific figure is not directly cited for them.
  • Ballistic capsules (Mercury/Vostok/Voskhod) have no lift — an offset-CG lift vector was not yet used; they ate the full ~8 g. Correct to keep them lift-free.
  • Suborbital gap (honest): the two Mercury-Redstone hops (freedom-7, liberty-bell-7) read ~8.7 g in the model vs the flown ~11 g. Their 18° entry angle + drag area are model estimates (marked in estimatedFields), unclosed — a known low-fidelity corner, not a sourced match.

How the Orrery model uses these ​

  • Profiles set liftToDragRatio (sourced), entryCdA (Apollo sourced, others geometry-derived), flightPathAngleDeg (~1.5° LEO deorbit, estimate), targetDownrangeKm (estimate). The estimated fields are declared in each profile's estimatedFields; a test enforces it (ADR-088 Phase 0b/1a).
  • Known model gap (honest): the range-control solve flies a single fixed bank, so modeled guided peak-g runs above the flown value for low-L/D capsules — Apollo 4.2 g (flown 3.3), Soyuz 5.6 g (flown 3–4), Shenzhou 5.0 g (flown ≤4), Dragon 5.3 g (flown ~4); i.e. +1 to +2.6 g. Real vehicles actively bank-modulate to hold a g-limit. Measured negative result: wiring the kernel's own decel-hold controller (bankLiftFraction) does NOT close this — it overshoots (Apollo target 3 g → peak ~6 g, worse than the fixed bank's ~4.2 g), because early in entry, with g below target, it digs in to build g. Holding a target g genuinely needs a predictor-corrector (integrate-ahead) controller, which is a large build; the residual stands documented, not faked. Separately, at lunar-return energy the capsule lofts/skips, which the #29 loft model DOES reproduce (ADR-089).

Source library ​

Orrery · docs/reference/capsule-entry-aerodynamics.md · created 2026-08-31 (ADR-088 Phase 1a)

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