Flight model

References

1. ^ abIn the US version of Pilotwings 64, the gyrocopter's update routine func_8030399C clears a vector (unk31C) and has five routines add terms to it: func_80307A9C, func_80307E2C, func_80308478, func_80307BAC, and func_80307EA8. A routine chosen by state can add to it after them (func_80304B98, for states 1 and 4, does), and func_80309090 copies the result to unk1AC. In state 1 (unkC0), the routine adds unk1AC times the frame time to the craft's velocity (unk190), with no mass dividing it; in state 0 it first combines unk1AC with cross terms of the velocity and the turn rates (unk1B8). func_80307E2C adds (0, 0, −9.8), z being the world's vertical, turned into the craft's frame through the inverse of its matrix (by the atlas's reading, gravity). func_80307A9C adds, on each of the craft's axes, a curve of the square of unk364's component on that axis, signed like the component: 0 at 0, 4.2 at 2661.2188, and 7.56 at 6944.389 and above, linear between (by the atlas's reading, air resistance). Those squares are speeds of about 51.59 and 83.33 (computed). func_80308478 sets unk364 to the vector env_802E1754 returns for the craft's position, in the craft's frame, less the craft's velocity, and adds 0.21 of that vector as a term of its own; by the atlas's reading the vector is the air's velocity and unk364 the airspeed. Below a speed (unk1A8) of 51.587303 the vector is scaled by the square of the speed over 51.587303, and outside state 0 it's taken as zero. The other two routines are in pw64/gyrocopter-lift.Coden64decomp/pw64revised
   How we know

   251void func_8030399C(GyrocopterData* gcData) {
   ⋮
   265    gcData->unk31C.x = 0.0f;
   ⋮
   274    func_80307A9C(gcData);
   275    func_80307E2C(gcData);
   276    func_80308478(gcData);
   277    func_80307BAC(gcData);
   278    func_80307EA8(gcData);
   

   349    uvMat4Copy(&gcData->unk150, &gcData->unk10);
   350    uvMat4InvertTranslationRotation(&gcData->unk110, &gcData->unk150);
   351    if (gcData->unkC0 == 1) {
   352        gcData->unk190.x += D_8034F854 * gcData->unk1AC.x;
   ⋮
   355        uvMat4LocalToWorld(&gcData->unk150, &gcData->unk19C, &gcData->unk190);
   356    } else {
   357        gcData->unk19C.x += D_8034F854 * gcData->unk1B8.x;
   ⋮
   360        uvMat4LocalToWorld(&gcData->unk110, &gcData->unk190, &gcData->unk19C);
   ⋮
   363    gcData->unk10.m[3][0] = (gcData->unk19C.x * D_8034F854) + spF4;
   

   280    switch (gcData->unkC0) {
   281    case 0:
   282        func_80304738(gcData);
   283        break;
   284    case 1:
   285    case 4:
   286        func_80304B98(gcData);
   287        break;
   ⋮
   290        break;
   ⋮
   294        break;
   ⋮
   296    func_80309090(gcData);
   297    if ((gcData->unkC0 == 0) && (gcData->unk190.z < gcData->unk190.y) && (gcData->unk6D == 0)) {
   ⋮
   

   1818void func_80309090(GyrocopterData* gcData) {
   ⋮
   1826        gcData->unk1AC.x = gcData->unk31C.x;
   ⋮
   1835    gcData->unk1AC.x = gcData->unk31C.x;
   

   566void func_80304B98(GyrocopterData* gcData) {
   ⋮
   623        uvVec3Add(&gcData->unk31C, &gcData->unk31C, &sp11C);
   

   1442void func_80307E2C(GyrocopterData* gcData) {
   ⋮
   1447    sp1C.z = -9.8f;
   1448    uvMat4LocalToWorld(&gcData->unk110, &gcData->unk358, &sp1C);
   1449    gcData->unk31C.x += gcData->unk358.x;
   

   122    D_80369528.count = 3;
   123    D_80369528.unk4[0].x = 0.f, D_80369528.unk4[0].y = 0.0f;
   124    D_80369528.unk4[1].x = 2661.2188f, D_80369528.unk4[1].y = 4.2f;
   125    D_80369528.unk4[2].x = 6944.389f, D_80369528.unk4[2].y = 7.5599995f;
   

   1360void func_80307A9C(GyrocopterData* gcData) {
   ⋮
   1363    sp24.x = func_80313F08(&D_80369528, SQ(gcData->unk364.x));
   1364    if (gcData->unk364.x < 0.0f) {
   1365        sp24.x = -sp24.x;
   ⋮
   1377    gcData->unk31C.x += sp24.x;
   

   257f32 func_80313F08(Unk803599D0* arg0, f32 arg1) {
   ⋮
   263    if (arg1 <= arg0->unk4[0].f[0]) {
   264        return arg0->unk4[0].f[1];
   ⋮
   267    if (arg0->unk4[arg0->count - 1].f[0] <= arg1) {
   268        return arg0->unk4[arg0->count - 1].f[1];
   ⋮
   278    temp_fv1 = (arg1 - prev->f[0]) / (cur->f[0] - prev->f[0]);
   279    return (cur->f[1] * temp_fv1) + (prev->f[1] * (1.0f - temp_fv1));
   

   1563void func_80308478(GyrocopterData* gcData) {
   ⋮
   1568    if (gcData->unkC0 == 0) {
   1569        env_802E1754(gcData->unk10.m[3][0], gcData->unk10.m[3][1], gcData->unk10.m[3][2], &sp38);
   1570        uvMat4LocalToWorld(&gcData->unk110, &sp44, &sp38);
   ⋮
   1577        } else {
   ⋮
   1580    } else {
   1581        sp44.x = sp44.y = sp44.z = 0.0f;
   ⋮
   1586    if (gcData->unk1A8 < 51.587303f) {
   1587        temp_fv0 = gcData->unk1A8 / 51.587303f;
   1588        temp_fv0 = SQ(temp_fv0);
   1589        sp44.x *= temp_fv0;
   ⋮
   1596    gcData->unk364.x = sp44.x - gcData->unk190.x;
   ⋮
   

   410    gcData->unk1A8 = uvVec3Len(&gcData->unk19C);
   

   471            hud->altSeaLevel = gcData->unk10.m[3][2] * 0.7f;
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Revised after a check by a second AI model, 2026-10-22.

   In the claim ledger

2. ^ abIn the US version of Pilotwings 64, two of the terms the gyrocopter's func_8030399C sums give it lift, by the atlas's reading. The one the atlas calls the rotor term (func_80307BAC) is 0.3 times the square of the airspeed's component on the z axis of the matrix unk25C, signed like that component and capped at 200 when positive, times the square of the airspeed's y component over 25, held between 0.05 and 1; it's added along the z axis of the matrix unk21C. The one it calls the engine term (func_80307EA8), while usingFuel is set, is 35 × power (unkB4) × a factor of height (spD8, the atlas's altitude factor), split 0.24 onto y and 0.76 onto z, the z part also times a curve of the negated y airspeed: 0 at 0, 0.15 at 10, 0.4 at 20, 1.2 at 50, and 1.5 at 100 and above. It too goes through unk21C, and its y component is cut to 0.9 when unk1F0 is nonzero, unk190.y is positive, and unk7C is 0. That factor is 1 up to a height of 700 and falls by 0.01 per unit above it, held at 0 from 800 up; that hold is under #if !defined(VERSION_JP), so a Japanese build lets the factor go negative. Neither term applies while unkC1 is set or in state 2 (unkC0).Coden64decomp/pw64revised
   How we know

   1382void func_80307BAC(GyrocopterData* gcData) {
   ⋮
   1403    if ((gcData->unkC1 != 0) || (gcData->unkC0 == 2)) {
   1404        gcData->unkE8 = func_80313AF4(0.0f, gcData->unkE8, 0.5f);
   1405        return;
   ⋮
   1407    uvMat4LocalToWorld(&gcData->unk25C, &sp34, &gcData->unk364);
   1408    sp54 = -(0.3f * sp34.z * sp34.z);
   1409    if (-sp34.z < 0.0f) {
   1410        sp54 = -sp54;
   1411        if (sp54 < -10.0f) {
   1412            sp54 = -10.0f;
   ⋮
   1414        if (sp54 > 200.0f) {
   1415            sp54 = 200.0f;
   ⋮
   

   1454void func_80307EA8(GyrocopterData* gcData) {
   ⋮
   1460    if ((gcData->unkC1 != 0) || (gcData->unkC0 == 2)) {
   1461        gcData->unkF0 = func_80313AF4(0.0f, gcData->unkF0, 0.5f);
   1462        return;
   

   1490    if (gcData->unk10.m[3][2] > 700.0f) {
   1491        spD8 = 1.0f - ((gcData->unk10.m[3][2] - 700.0f) / 100.0f);
   1492#if !defined(VERSION_JP)
   1493        if (spD8 < 0.0f) {
   1494            spD8 = 0.0f;
   ⋮
   1496#endif
   1497    } else {
   1498        spD8 = 1.0f;
   ⋮
   1500    if (gcData->usingFuel) {
   1501        temp_fv0 = func_80313F08(&D_803692C0, -gcData->unk364.y);
   1502        spDC.x = 0.0f;
   1503        spDC.y = gcData->unkB4 * 0.24f * spD8 * 35.0f;
   ⋮
   

   74    D_803692C0.count = 5;
   75    D_803692C0.unk4[0].x = 0.0f, D_803692C0.unk4[0].y = 0.f;
   76    D_803692C0.unk4[1].x = 10.0f, D_803692C0.unk4[1].y = 0.15f;
   77    D_803692C0.unk4[2].x = 20.0f, D_803692C0.unk4[2].y = 0.4f;
   78    D_803692C0.unk4[3].x = 50.0f, D_803692C0.unk4[3].y = 1.2f;
   79    D_803692C0.unk4[4].x = 100.0f, D_803692C0.unk4[4].y = 1.5f;
   

   471            hud->altSeaLevel = gcData->unk10.m[3][2] * 0.7f;
   ⋮
   473            if (hud->fuel > 0.0f) {
   474                hud->power = gcData->unkB4;
   

   Checked against the evidence by its author, an AI model, 2026-10-22.

   Revised after a check by a second AI model, 2026-10-22.

   In the claim ledger