Compatibility

Compatibility

Relativity is a force/rate layer - it never rewrites orbits or moves vessels directly, which is what makes it safe with n-body physics. It has no dependency on any planet pack. Below is the player-facing summary; the full engineering matrix is in the repo's docs/compatibility.md.

Required

Mod	Status
Harmony (Harmony2)	Required. All the runtime adapters need it. Use the shared KSP-packaged copy.

Physics & frame

Mod	Status
Principia	✅ Safe by design - the headline compatibility claim. The mod modulates force and rate only, never the integrator, and Principia even supplies barycentric velocity for free. Rule Principia shares: never move a vessel or rewrite an orbit directly - this mod doesn't.
SigmaBinary	✅ Compatible - the barycentric-frame reasoning holds on both stock and Principia profiles.
Kopernicus / planet packs	✅ Agnostic - the mod reads no planet data. Only the planner's optional "pick a body" distance mode queries whatever bodies exist.

Life support (the resource-dilation half)

The 1/γ resource slowdown works through per-framework adapters. With no life-support mod installed it is simply inert - thrust, dashboard, crew clock, and planner all still work.

Mod	Status
Kerbalism 3.x / ROKerbalism	✅ Primary path - metabolic use dilated ×1/γ, radiation excluded (dose stays coordinate-time). The only framework that models dose, so the dashboard's dose row is gated on it. Toggle with kerbalismDilation.
Snacks!, USI-LS, TAC-LS	Supported via named adapters (best-effort; background/catch-up differs per mod).
Community Resource Pack (CRP)	✅ Definitions only - nothing to hook.

Kerbalism's own old relativistic-time feature was removed in the v3 rewrite, so there is no double-dilation with current Kerbalism. On a pre-v3 install, turn its RelativisticTime off.

Career

Mod	Status
RP-1	Relativistic-retirement adapter - a returning crew's retirement date is pushed forward by their dilation (counts proper time). Compile-verified; not yet run with RP-1 installed. Toggle with rp1RetirementDilation.

Propulsion (what gets you to relativistic speed)

The mod is inert until something reaches a relativistic β - it ships no drive of its own.

Mod	Status
Far Future Technologies, Near Future Propulsion	✅ Natural drive suppliers; no relativity of their own to conflict.
KSP Interstellar Extended (KSPIE)	⚠️ Its Daedalus engine already applies a γ⁻² thrust falloff - detected to avoid double-applying dilation.
Persistent Thrust	Background/warp thrust is an orbit edit the loaded force hook can't see. This release tracks the crew clock through it but does not yet apply the 1/γ³ thrust cut to unloaded PT (deferred - see FAQ and the roadmap).

Warp / FTL - the WarpFlag extension point

Warp motion is not real speed-through-space, so the layer must switch off during it. Warp mods raise a generic WarpFlag and the dashboard shows a collapsed WARP panel.

Mod	Status
Blueshift, KSPIE Alcubierre	✅ Detected → raise WarpFlag, show warp speed in c.
WarpThrust	⚠️ Not FTL - it's genuine sublight Δv, so it must not trip WarpFlag. Treated as a thrust-field coexistence case.

Autopilots & time-warp

Because the mod cuts thrust with a corrective force, an engine's advertised thrust/ISP are left unchanged - only the net applied force becomes F/γ³. So tools that estimate from reported thrust are blind to the reduction near c.

Mod	Status
MechJeb	⚠️ Burn-time estimates and node timing computed from reported thrust will under-estimate near c; measured-acceleration executors partially self-correct. A first-class fix is on the roadmap (v0.2). Attitude 1/γ is surfaced as a torque reduction so MechJeb's turn predictions stay self-consistent.
kOS	⚠️ Same thrust blind spot. Closed-loop steering on measured angular velocity is fine; only a script that hardcodes a turn deadline (instead of polling angle error) would misbehave.
Time Control / Better Time Warp	✅ The crew-clock accumulator reads live fixedDeltaTime + actual UT delta, so custom warp-rate tables are handled.
Kerbal Alarm Clock	✅ Agnostic.

See also

• Configuration - the toggles referenced above.
• FAQ - the MechJeb/kOS thrust blind spot explained.