Max range display is the guaranteed (worst-case headwind) full-tank range (ISS-099, v0.51.0)

2026-09-22 08:24:09 +00:00
parent d215203988
commit dc2f2b420b
7 changed files with 69 additions and 13 deletions
@@ -5,6 +5,8 @@ import {
  burnRateConstant,
  FUEL_DENSITY_KG_PER_L,
  fuelAtWeighted,
+  guaranteedRangeKm,
+  MAX_WIND_BURN_FACTOR,
  maxRangeKm,
  positionAt,
  progressAt,
@@ -234,3 +236,22 @@ describe('maxRangeKm (v0.28.0)', () => {
    expect(() => maxRangeKm(BURN, 0, TANK)).toThrow();
  });
 });
+
+describe('guaranteedRangeKm (v0.51.0, ISS-099)', () => {
+  it("MAX_WIND_BURN_FACTOR is windBurnFactor's actual maximum over the weather domain", () => {
+    // Full headwind at max wind: exactly +20% — the constant must track the factor function, not a copy.
+    expect(MAX_WIND_BURN_FACTOR).toBe(windBurnFactor(30, 90, 90));
+  });
+
+  it('is maxRangeKm under worst-case headwind burn (ATR ≈ 3696 km ±5%)', () => {
+    const r = guaranteedRangeKm(BURN, WE, TANK);
+    expect(r).toBeCloseTo(maxRangeKm(BURN * MAX_WIND_BURN_FACTOR, WE, TANK), 12);
+    expect(r).toBeGreaterThan(3696 * 0.95);
+    expect(r).toBeLessThan(3696 * 1.05);
+  });
+
+  it('zero fuel → zero range; rejects a non-positive empty weight', () => {
+    expect(guaranteedRangeKm(BURN, WE, 0)).toBe(0);
+    expect(() => guaranteedRangeKm(BURN, 0, TANK)).toThrow();
+  });
+});