170 lines
6.3 KiB
C++
170 lines
6.3 KiB
C++
#ifndef ECON_SPD
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#define ECON_SPD
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// Feet
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#define MIN_FL 10
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#define MAX_FL 430
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// Tonnes
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#define MIN_WGT 140
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#define MAX_WGT 290
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// Percent
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#define MIN_TIP 60
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#define MAX_TIP 90
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// Mach
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#define MIN_MMO 0.85
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#define MAX_MMO 0.87
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// 10x Feet
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#define FL_STP 20
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// 10x Kilogrammes
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#define WGT_STP 10
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// Percent
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#define TIP_STP 30.0
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#include "ci2mach_0.85.h"
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#include "ci2mach_0.87.h"
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#include <algorithm>
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#include <cmath>
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#include <tuple>
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/// @brief Round to n decimal places
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/// @param value Value to round
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/// @param decimals Number of decimal places
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/// @return Rounded value
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float roundTo(float value, char decimals) {
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return std::roundf(value * std::pow(10, decimals)) / std::pow(10, decimals);
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}
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/// @brief Bounding function for altitudes in accordance with data granularity
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/// @param altitude Altitude in ft
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/// @return Lower bound in FL, upper bound in FL, ratio between bounds that equates to flightLevel
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std::tuple<int, int, float> boundAltitude(int altitude) {
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int flightLevel = (int)round(altitude / 100.0);
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float lower = flightLevel - ((flightLevel - MIN_FL) % FL_STP);
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float upper = (flightLevel - MIN_FL) % FL_STP != 0 ? lower + FL_STP : lower;
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float ratio = (flightLevel - lower) / FL_STP;
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return {(int)lower, (int)upper, ratio};
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}
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/// @brief Bounding function for weight in accordance with data granularity
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/// @param weight Weight in kilogrammes
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/// @return Lower bound in t, upper bound in t, ratio between bounds that equates to weight
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std::tuple<int, int, float> boundWeight(int weight) {
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int wgt = (int)round(weight / 1000.0);
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float lower = wgt - ((wgt - MIN_WGT) % WGT_STP);
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float upper = (wgt - MIN_WGT) % WGT_STP != 0 ? lower + WGT_STP : lower;
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float ratio = ((weight / 1000.0) - lower) / WGT_STP;
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return {(int)lower, (int)upper, ratio};
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}
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/// @brief Bounding function for MMO based on total fuel
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/// @param totalFuel Total fuel in kilogrammes
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/// @return Ratio between .85 and .87 MMO
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float boundMMO(float totalFuel) {
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float percent = (int)round(1.57613580e-02 * totalFuel - 1.51221174e+02);
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return percent <= MIN_TIP ? 0 :
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percent >= MAX_TIP ? 1 :
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(percent - MIN_TIP) / TIP_STP;
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}
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/// @brief Conversion from FL to index of file
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/// @param flightLevel FL to convert
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/// @return Index in file
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int flightLevel2Index(int flightLevel) {
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return (flightLevel - MIN_FL) / FL_STP;
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}
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/// @brief Conversion from tonnes to index of file
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/// @param weight Weight in tonnes to convert
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/// @return Index in file
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int weight2Index(int weight) {
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return (weight - MIN_WGT) / WGT_STP;
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}
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/// @brief Linear interpolate between lower and upper
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/// @param lower Lower interpolation bound
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/// @param upper Upper interpolation bound
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/// @param ratio Ratio of interpolation between lower and upper
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/// @return Value at ratio between lower and upper
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float interp(float lower, float upper, float ratio) {
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return lower + (upper - lower) * ratio;
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}
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/// @brief Calculate mach for a given CI and aircraft state
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/// @param altitude Altitude in feet
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/// @param weight Weight in kilogrammes
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/// @param totalFuel Total fuel in kilogrammes EXCLUDING BALLAST
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/// @param ci CI
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/// @return Mach corresponding to CI. Returns -1 if not possible
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float ci2mach(float altitude, float weight, float totalFuel, int ci) {
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// Some fallback assumptions for extreme cases
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// Clamp weight, for <140 we use 140
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weight = std::clamp(weight, 140000.0f, 290000.0f);
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// Clamp altitude, for > 43000 we use 43000, for <1000 we use 1000
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altitude = std::clamp(altitude, 1000.0f, 43000.0f);
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// Safety CI
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ci = std::clamp(ci, 0, 999);
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auto bAlt = boundAltitude(altitude);
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int lowerFl = std::get<0>(bAlt);
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int upperFl = std::get<1>(bAlt);
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float ratioFl = std::get<2>(bAlt);
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auto bWgt = boundWeight(weight);
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int lowerWgt = std::get<0>(bWgt);
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int upperWgt = std::get<1>(bWgt);
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float ratioWgt = std::get<2>(bWgt);
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float ratioMMO = boundMMO(totalFuel);
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int lowerFlIndex = flightLevel2Index(lowerFl);
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int upperFlIndex = flightLevel2Index(upperFl);
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int lowerWgtIndex = weight2Index(lowerWgt);
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int upperWgtIndex = weight2Index(upperWgt);
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// Outside of the maximum indicies, safeguard us from out-of-bounds
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if (lowerFlIndex > 21 || upperFlIndex > 21 || lowerWgtIndex > 15 || upperWgtIndex > 15 ||
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lowerFlIndex < 0 || upperFlIndex < 0 || lowerWgtIndex < 0 || upperWgtIndex < 0) {
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return -1;
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}
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const float* lowerFlLowerWgtCis85 = ci2Mach_85->values[lowerFlIndex][lowerWgtIndex];
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const float* lowerFlUpperWgtCis85 = ci2Mach_85->values[lowerFlIndex][upperWgtIndex];
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const float* upperFlLowerWgtCis85 = ci2Mach_85->values[upperFlIndex][lowerWgtIndex];
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const float* upperFlUpperWgtCis85 = ci2Mach_85->values[upperFlIndex][upperWgtIndex];
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const float* lowerFlLowerWgtCis87 = ci2Mach_87->values[lowerFlIndex][lowerWgtIndex];
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const float* lowerFlUpperWgtCis87 = ci2Mach_87->values[lowerFlIndex][upperWgtIndex];
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const float* upperFlLowerWgtCis87 = ci2Mach_87->values[upperFlIndex][lowerWgtIndex];
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const float* upperFlUpperWgtCis87 = ci2Mach_87->values[upperFlIndex][upperWgtIndex];
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float lowerFlLowerWgtMach85 = lowerFlLowerWgtCis85[ci];
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float lowerFlUpperWgtMach85 = lowerFlUpperWgtCis85[ci];
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float upperFlLowerWgtMach85 = upperFlLowerWgtCis85[ci];
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float upperFlUpperWgtMach85 = upperFlUpperWgtCis85[ci];
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float lowerFlLowerWgtMach87 = lowerFlLowerWgtCis87[ci];
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float lowerFlUpperWgtMach87 = lowerFlUpperWgtCis87[ci];
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float upperFlLowerWgtMach87 = upperFlLowerWgtCis87[ci];
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float upperFlUpperWgtMach87 = upperFlUpperWgtCis87[ci];
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// Outside operational limits
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if (upperFlUpperWgtMach87 < 0 || upperFlUpperWgtMach85 < 0 || upperFlLowerWgtMach87 < 0 || upperFlLowerWgtMach85 < 0 ||
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lowerFlUpperWgtMach87 < 0 || lowerFlUpperWgtMach85 < 0 || lowerFlLowerWgtMach87 < 0 || lowerFlLowerWgtMach85 < 0) {
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return -1;
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}
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float ratioedLowerFlMach85 = interp(lowerFlLowerWgtMach85, lowerFlUpperWgtMach85, ratioWgt);
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float ratioedUpperFlMach85 = interp(upperFlLowerWgtMach85, upperFlUpperWgtMach85, ratioWgt);
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float ratioedMach85 = interp(ratioedLowerFlMach85, ratioedUpperFlMach85, ratioFl);
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float ratioedLowerFlMach87 = interp(lowerFlLowerWgtMach87, lowerFlUpperWgtMach87, ratioWgt);
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float ratioedUpperFlMach87 = interp(upperFlLowerWgtMach87, upperFlUpperWgtMach87, ratioWgt);
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float ratioedMach87 = interp(ratioedLowerFlMach87, ratioedUpperFlMach87, ratioFl);
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return roundTo(interp(ratioedMach85, ratioedMach87, ratioMMO), 3);
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}
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#endif |