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Space Combat Physics

Development analysis of local prototype models. Current rules, game data, and book material live in Google Drive. This generated output is not rules authority and does not automatically synchronize with Drive.

Vacuum removes wind, drop and drag, and replaces them with light-lag, enormous flight times, and the impossibility of hiding.

Light-lag and flight time

Sensors show where a target was. Drift is what a target can actually achieve given a delta-v budget, not what a sustained 1 g burn would produce — an earlier version tabulated 1 g for months, which at the far end silently required 0.82c of delta-v.

Drift below assumes a 15 km/s budget spent evading, which is a well-found warship.

The qualitative result stands and is now honestly derived: past a few thousand kilometres a target drifts further than its own length during flight time, so unguided fire stops being aimed at a ship. Guided weapons dominate at range, point defence is the real battle, and closing is a deliberate tactic.

Firing a 6 km/s slug across an AU is not a tactic anyone would attempt; the far rows exist to show where the approach dies, not to suggest using it.

There is no stealth in space

A ship must radiate waste heat or cook its crew.

Assumes an isotropic radiator at emissivity 1 against a dedicated cryogenic sensor. Directional radiators buy a real reduction toward a known threat axis, and an all-sky search takes time — which is exactly why the achievable goal is ambiguity, not invisibility. Being one contact among many, hiding your vector, or looking like cargo all work. Being invisible does not.

Delta-v is the currency

dv = Isp g ln(wet mass / dry mass)