Updates to trial engine model.
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curt
parent
306f01c41a
commit
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5 changed files with 54 additions and 56 deletions
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@ -64,9 +64,7 @@ float FGEngine::Calc_Engine_RPM (float LeverPosition)
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// Calculate RPM as set by Prop Lever Position. Assumes engine
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// will run at 1000 RPM at full course
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float RPM;
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RPM = LeverPosition * Max_RPM / 100.0;
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// * ((FGEng_Max_RPM + FGEng_Min_RPM) / 100);
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float RPM = LeverPosition * (Max_RPM - Min_RPM) /100 + Min_RPM ;
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if ( RPM >= Max_RPM ) {
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RPM = Max_RPM;
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@ -110,7 +108,7 @@ void FGEngine::init() {
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// Initialise Engine Variables used by this instance
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Percentage_Power = 0;
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Manifold_Pressure = 29.00; // Inches
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RPM = 2700;
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RPM = 500;
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Fuel_Flow = 0; // lbs/hour
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Torque = 0;
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CHT = 370;
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@ -132,6 +130,7 @@ void FGEngine::init() {
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Alpha1 = 13.5;
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FGProp1_Blade_Angle = 13.5;
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FGProp_Fine_Pitch_Stop = 13.5;
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FGProp_Course_Pitch_Stop = 55;
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// Other internal values
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Rho = 0.002378;
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@ -176,46 +175,43 @@ static float Calc_CHT (float Fuel_Flow, float Mixture, float IAS)
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// Calculate Density Ratio
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static float Density_Ratio ( float x )
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{
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float y ;
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y = ((3E-10 * x * x) - (3E-05 * x) + 0.9998);
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return(y);
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float y = ((3E-10 * x * x) - (3E-05 * x) + 0.9998);
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return y;
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}
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// Calculate Air Density - Rho
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static float Density ( float x )
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{
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float y ;
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y = ((9E-08 * x * x) - (7E-08 * x) + 0.0024);
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return(y);
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float y = ((9E-08 * x * x) - (7E-08 * x) + 0.0024);
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return y;
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}
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// Calculate Speed in FPS given Knots CAS
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static float IAS_to_FPS (float x)
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static float IAS_to_FPS (float ias)
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{
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float y;
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y = x * 1.68888888;
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return y;
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return ias * 1.68888888;
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}
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// update the engine model based on current control positions
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void FGEngine::update() {
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// Declare local variables
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int num = 0;
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const int num2 = 1; // default is 100, number if iterations to run
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int num = 0; // Not used. Counting variables
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int num2 = 100; // Not used.
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float ManXRPM = 0;
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float Vo = 0;
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float V1 = 0;
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// Set up the new variables
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float Blade_Station = 30;
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float Rho = 0.002378;
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float FGProp_Area = 1.405/3;
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float PI = 3.1428571;
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// Input Variables
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// float IAS = 0;
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// 0 = Closed, 100 = Fully Open
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// float Throttle_Lever_Pos = 75;
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@ -226,7 +222,7 @@ void FGEngine::update() {
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// Environmental Variables
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// Temp Variation from ISA (Deg F)
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// Temp Variation from ISA (Deg F)
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float FG_ISA_VAR = 0;
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// Pressure Altitude 1000's of Feet
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float FG_Pressure_Ht = 0;
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@ -269,48 +265,44 @@ void FGEngine::update() {
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Manifold_Pressure =
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Calc_Manifold_Pressure( Throttle_Lever_Pos, Max_Manifold_Pressure );
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// cout << "manifold pressure = " << Manifold_Pressure << endl;
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cout << "manifold pressure = " << Manifold_Pressure << endl;
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// Calculate Manifold Pressure (Engine 2) as set by throttle opening
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// FGEng2_Manifold_Pressure = Manifold_Pressure(FGEng2_Throttle_Lever_Pos, FGEng2_Manifold_Pressure);
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// Show_Manifold_Pressure(FGEng2_Manifold_Pressure);
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RPM = Calc_Engine_RPM(Propeller_Lever_Pos);
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// cout << "Engine RPM = " << RPM << endl;
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Desired_RPM = RPM;
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cout << "Desired RPM = " << Desired_RPM << endl;
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//==================================================================
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// Engine Power & Torque Calculations
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// Loop until stable - required for testing only
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for (num = 0; num < num2; num++) {
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// cout << Manifold_Pressure << " Inches" << "\t";
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// cout << RPM << " RPM" << "\t";
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// cout << endl << "====================" << endl;
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// cout << "MP Inches = " << Manifold_Pressure << "\t";
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// cout << " RPM = " << RPM << "\t";
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// For a given Manifold Pressure and RPM calculate the % Power
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// Multiply Manifold Pressure by RPM
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ManXRPM = Manifold_Pressure * RPM;
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// cout << ManXRPM;
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// cout << endl;
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// cout << ManXRPM << endl;
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// Calculate % Power
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Percentage_Power = (+ 7E-09 * ManXRPM * ManXRPM)
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+ ( + 7E-04 * ManXRPM) - 0.1218;
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// cout << Percentage_Power << "%" << "\t";
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// cout << "percent power = " << Percentage_Power << "%" << "\t";
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// Adjust for Temperature - Temperature above Standard decrease
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// power % by 7/120 per degree F increase, and incease power for
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// temps below at the same ratio
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Percentage_Power = Percentage_Power - (FG_ISA_VAR * 7 /120);
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// cout << Percentage_Power << "%" << "\t";
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// cout << " adjusted T = " << Percentage_Power << "%" << "\t";
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// Adjust for Altitude. In this version a linear variation is
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// used. Decrease 1% for each 1000' increase in Altitde
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Percentage_Power = Percentage_Power + (FG_Pressure_Ht * 12/10000);
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// cout << Percentage_Power << "%" << "\t";
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// cout << " adjusted A = " << Percentage_Power << "%" << "\t";
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// Now Calculate Fuel Flow based on % Power Best Power Mixture
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Fuel_Flow = Percentage_Power * Max_Fuel_Flow / 100.0;
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@ -327,8 +319,8 @@ void FGEngine::update() {
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Percentage_Power = Percentage_Power *
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((100.0 - Mag_Derate_Percent)/100.0);
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// cout << FGEng1_Percentage_Power << "%" << "\t";
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}
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// cout << "Final engine % power = " << Percentage_Power << "%" << endl;
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// Calculate Engine Horsepower
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@ -357,7 +349,7 @@ void FGEngine::update() {
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//Radial Flow Vector (V2) Ft/sec at Ref Blade Station (usually 30")
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FGProp1_Angular_V = FGProp1_RPS * 2 * PI * (Blade_Station / 12);
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// cout << FGProp1_Angular_V << "Angular Velocity " << endl;
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// cout << "Angular Velocity " << FGProp1_Angular_V << endl;
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// Axial Flow Vector (Vo) Ft/sec
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// Some further work required here to allow for inflow at low speeds
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@ -370,19 +362,24 @@ void FGEngine::update() {
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// Relative Velocity (V1)
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V1 = sqrt((FGProp1_Angular_V * FGProp1_Angular_V) +
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(Vo * Vo));
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// cout << V1 << "Relative Velocity " << endl;
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// cout << "Relative Velocity " << V1 << endl;
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if ( FGProp1_Blade_Angle >= FGProp_Course_Pitch_Stop ) {
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FGProp1_Blade_Angle = FGProp_Course_Pitch_Stop;
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}
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// cout << FGProp1_Blade_Angle << " Prop Blade Angle" << endl;
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// Blade Angle of Attack (Alpha1)
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cout << " Alpha1 = " << Alpha1
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<< " Blade angle = " << FGProp1_Blade_Angle
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<< " Vo = " << Vo
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<< " FGProp1_Angular_V = " << FGProp1_Angular_V << endl;
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Alpha1 = FGProp1_Blade_Angle -(atan(Vo / FGProp1_Angular_V) * (180/PI));
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// cout << Alpha1 << " Alpha1" << endl;
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// cout << " Alpha1 = " << Alpha1
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// << " Blade angle = " << FGProp1_Blade_Angle
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// << " Vo = " << Vo
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// << " FGProp1_Angular_V = " << FGProp1_Angular_V << endl;
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// Calculate Coefficient of Drag at Alpha1
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FGProp1_Coef_Drag = (0.0005 * (Alpha1 * Alpha1)) + (0.0003 * Alpha1)
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+ 0.0094;
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@ -401,21 +398,20 @@ void FGEngine::update() {
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* ((FGProp1_Coef_Lift * sin(Alpha1 * PI / 180))
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+ (FGProp1_Coef_Drag * cos(Alpha1 * PI / 180))))
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* (Blade_Station/12);
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// cout << FGProp1_Torque << " Prop Torque" << endl;
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// cout << "Prop Torque = " << FGProp1_Torque << endl;
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// Calculate Prop Thrust
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// cout << " V1 = " << V1 << " Alpha1 = " << Alpha1 << endl;
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FGProp1_Thrust = 0.5 * Rho * (V1 * V1) * FGProp_Area
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* ((FGProp1_Coef_Lift * cos(Alpha1 * PI / 180))
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- (FGProp1_Coef_Drag * sin(Alpha1 * PI / 180)));
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// cout << FGProp1_Thrust << " Prop Thrust " << endl;
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// cout << " Prop Thrust = " << FGProp1_Thrust << endl;
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// End of Propeller Calculations
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//==============================================================
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#if 0
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Torque_Imbalance = FGProp1_Torque - Torque;
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// cout << Torque_Imbalance << endl;
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@ -437,7 +433,6 @@ void FGEngine::update() {
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if (RPM >= 2700) {
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RPM = 2700;
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}
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#endif
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// cout << FGEng1_RPM << " Blade_Angle " << FGProp1_Blade_Angle << endl << endl;
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@ -104,6 +104,7 @@ private:
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float Alpha1;
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float FGProp1_Blade_Angle;
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float FGProp_Fine_Pitch_Stop;
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float FGProp_Course_Pitch_Stop;
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// Other internal values
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float Rho;
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@ -35,6 +35,7 @@
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#include "LaRCsim.hxx"
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#define USE_NEW_ENGINE_CODE 1
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FGEngine eng;
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@ -87,12 +88,12 @@ int FGLaRCsim::update( int multiloop ) {
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#ifdef USE_NEW_ENGINE_CODE
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// update simple engine model
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eng.set_IAS( V_calibrated_kts );
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eng.set_Throttle_Lever_Pos( Throttle_pct * 100.0 );
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eng.set_Throttle_Lever_Pos( controls.get_throttle( 0 ) * 100.0 );
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eng.set_Propeller_Lever_Pos( 95 );
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eng.set_Mixture_Lever_Pos( 100 );
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eng.update();
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cout << " Thrust = " << eng.get_FGProp1_Thrust() << endl;
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F_X_engine = eng.get_FGProp1_Thrust() * 7;
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F_X_engine = eng.get_FGProp1_Thrust() * 1.5;
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#endif
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double save_alt = 0.0;
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@ -11,10 +11,12 @@ libFlight_a_SOURCES = \
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LaRCsim.cxx LaRCsim.hxx \
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MagicCarpet.cxx MagicCarpet.hxx
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bin_PROGRAMS = engine
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bin_PROGRAMS = engine ps
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engine_SOURCES = engine.cxx
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engine_LDADD = libFlight.a
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ps_SOURCES = ps-10520c.cxx
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INCLUDES += -I$(top_builddir) -I$(top_builddir)/src
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@ -7,18 +7,17 @@ int main() {
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e.init();
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for ( int i = 0; i < 10000; ++i ) {
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e.set_IAS( 45 );
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e.set_Throttle_Lever_Pos( (double)i / 100.0 );
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e.set_Propeller_Lever_Pos( 100 );
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e.set_Mixture_Lever_Pos( 75 );
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e.set_IAS( 80 );
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e.set_Throttle_Lever_Pos( 50.0 );
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e.set_Propeller_Lever_Pos( 100.0 );
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e.set_Mixture_Lever_Pos( 75 );
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e.update();
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// cout << "Rho = " << e.get_Rho();
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cout << "Throttle = " << i / 100.0;
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cout << " RPM = " << e.get_RPM();
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cout << " Thrust = " << e.get_FGProp1_Thrust() << endl;
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}
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e.update();
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// cout << "Rho = " << e.get_Rho();
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cout << "Throttle = " << 100.0;
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cout << " RPM = " << e.get_RPM();
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cout << " Thrust = " << e.get_FGProp1_Thrust() << endl;
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return 0;
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}
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