2 // Author: Phil Schubert
3 // Date started: 12/03/99
4 // Purpose: Models a Continental IO-520-M Engine
5 // Called by: FGSimExec
7 // Copyright (C) 1999 Philip L. Schubert (philip@zedley.com)
9 // This program is free software; you can redistribute it and/or
10 // modify it under the terms of the GNU General Public License as
11 // published by the Free Software Foundation; either version 2 of the
12 // License, or (at your option) any later version.
14 // This program is distributed in the hope that it will be useful, but
15 // WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 // General Public License for more details.
19 // You should have received a copy of the GNU General Public License
20 // along with this program; if not, write to the Free Software
21 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
24 // Further information about the GNU General Public License can also
25 // be found on the world wide web at http://www.gnu.org.
27 // FUNCTIONAL DESCRIPTION
28 // ------------------------------------------------------------------------
29 // Models a Continental IO-520-M engine. This engine is used in Cessna
30 // 210, 310, Beechcraft Bonaza and Baron C55. The equations used below
31 // were determined by a first and second order curve fits using Excel.
32 // The data is from the Cessna Aircraft Corporations Engine and Flight
33 // Computer for C310. Part Number D3500-13
36 // ------------------------------------------------------------------------
40 // ------------------------------------------------------------------------
41 // 12/03/99 PLS Created
42 // 07/03/99 PLS Added Calculation of Density, and Prop_Torque
43 // 07/03/99 PLS Restructered Variables to allow easier implementation
45 // 15/03/99 PLS Added Oil Pressure
46 // 19/8/2000 PLS Updated E-mail address - This version compiles
47 // 19/8/2000 PLS Set Max Prop blade angle to prevent prop exeeding 90
48 // ------------------------------------------------------------------------
50 // ------------------------------------------------------------------------
55 // #include "10520c.h"
57 // ------------------------------------------------------------------------
59 // ------------------------------------------------------------------------
61 // prototype definitions
62 // These should be in a header file 10520c.h
64 float Density (float x);
65 void ShowRho (float x);
67 float IAS_to_FPS (float x);
68 void ShowFPS(float x);
70 float Get_Throttle (float x);
71 void Show_Throttle (float x);
73 float Manifold_Pressure (float x, float z);
74 void Show_Manifold_Pressure (float x);
76 float CHT (float Fuel_Flow, float Mixture, float IAS);
77 void Show_CHT (float x);
79 float Oil_Temp (float x, float y);
80 void Show_Oil_Temp (float x);
82 float Oil_Press (float Oil_Temp, float Engine_RPM);
83 void Show_Oil_Press (float x);
88 // Declare local variables
89 int num = 0; // Not used. Counting variables
90 int num2 = 100; // Not used.
96 // Set up the new variables
97 float Blade_Station = 30;
99 float FGProp_Area = 1.405/3;
100 float PI = 3.1428571;
104 cout << "Enter IAS ";
110 // 0 = Closed, 100 = Fully Open
111 float FGEng1_Throttle_Lever_Pos = 75;
112 // 0 = Full Course 100 = Full Fine
113 float FGEng1_Propeller_Lever_Pos = 75;
114 // 0 = Idle Cut Off 100 = Full Rich
115 float FGEng1_Mixture_Lever_Pos = 100;
117 // Environmental Variables
119 // Temp Variation from ISA (Deg F)
120 float FG_ISA_VAR = 0;
121 // Pressure Altitude 1000's of Feet
122 float FG_Pressure_Ht = 0;
124 // Parameters that alter the operation of the engine.
125 // Yes = 1. Is there Fuel Available. Calculated elsewhere
126 int FGEng1_Fuel_Available = 1;
127 // Off = 0. Reduces power by 3 % for same throttle setting
128 int FGEng1_Alternate_Air_Pos =0;
129 // 1 = On. Reduces power by 5 % for same power lever settings
130 int FGEng1_Magneto_Left = 1;
131 // 1 = On. Ditto, Both of the above though do not alter fuel flow
132 int FGEng1_Magneto_Right = 1;
134 // There needs to be a section in here to trap silly values, like
135 // 0, otherwise they will crash the calculations
137 // Engine Specific Variables used by this program that have limits.
138 // Will be set in a parameter file to be read in to create
139 // and instance for each engine.
140 float FGEng_Max_Manifold_Pressure = 29.50;
141 float FGEng_Max_RPM = 2700;
142 float FGEng_Min_RPM = 1000;
143 float FGEng_Max_Fuel_Flow = 130;
144 float FGEng_Mag_Derate_Percent = 5;
145 float FGEng_MaxHP = 285;
146 float FGEng_Gear_Ratio = 1;
148 // Initialise Engine Variables used by this instance
149 float FGEng1_Percentage_Power = 0;
150 float FGEng1_Manifold_Pressure = 29.00; // Inches
151 float FGEng1_RPM = 500;
152 float FGEng1_Fuel_Flow = 0; // lbs/hour
153 float FGEng1_Torque = 0;
154 float FGEng1_CHT = 370;
155 float FGEng1_Mixture = 14;
156 float FGEng1_Oil_Pressure = 0; // PSI
157 float FGEng1_Oil_Temp = 85; // Deg C
159 float FGEng1_RPS = 0;
160 float Torque_Imbalance = 0;
161 float FGEng1_Desired_RPM = 0;
163 // Initialise Propellor Variables used by this instance
164 float FGProp1_Angular_V = 0;
165 float FGProp1_Coef_Drag = 0.6;
166 float FGProp1_Torque = 0;
167 float FGProp1_Thrust = 0;
168 float FGProp1_RPS = 0;
169 float FGProp1_Coef_Lift = 0.1;
171 float FGProp1_Blade_Angle = 13.5;
172 float FGProp_Fine_Pitch_Stop = 13.5;
173 float FGProp_Course_Pitch_Stop = 55;
175 // cout << "Enter Blade Angle ";
176 // cin >> FGProp1_Blade_Angle;
179 cout << " Number of Iterations ";
184 cout << " Throttle % ";
185 // cin >> FGEng1_Throttle_Lever_Pos;
186 FGEng1_Throttle_Lever_Pos = 50;
190 // cin >> FGEng1_Propeller_Lever_Pos;
191 FGEng1_Propeller_Lever_Pos = 100;
194 //==================================================================
195 // Engine & Environmental Inputs from elsewhere
197 // Calculate Air Density (Rho) - In FG this is calculated in
200 Rho = Density(FG_Pressure_Ht); // In FG FG_Pressure_Ht is "h"
204 // Calculate Manifold Pressure (Engine 1) as set by throttle opening
206 FGEng1_Manifold_Pressure = Manifold_Pressure(FGEng1_Throttle_Lever_Pos,
207 FGEng1_Manifold_Pressure );
208 Show_Manifold_Pressure(FGEng1_Manifold_Pressure);
210 // Calculate Desired RPM as set by Prop Lever Position.
211 // Actual engine RPM may be different
212 // The governed max RPM at 100% Prop Lever Position = FGEng_MaxRPM
213 // The governed minimum RPM at 0% Prop Lever Position = FGEng_Min_RPM
214 // The actual minimum RPM of the engine can be < FGEng_Min_RPM if there is insufficient
215 // engine torque to counter act the propeller torque at FGProp_Fine_Pitch_Stop
217 FGEng1_RPM = (FGEng1_Propeller_Lever_Pos * (FGEng_Max_RPM - FGEng_Min_RPM) /100)
220 // * ((FGEng_Max_RPM + FGEng_Min_RPM) / 100);
222 if (FGEng1_RPM >= 2700) {
225 FGEng1_Desired_RPM = FGEng1_RPM;
227 cout << "Desired RPM = " << FGEng1_Desired_RPM << endl;
229 //==================================================================
230 // Engine Power & Torque Calculations
232 // Loop until stable - required for testing only
233 for (num = 1; num < num2; num++) {
234 cout << endl << "====================" << endl;
235 cout << "MP Inches = " << FGEng1_Manifold_Pressure << "\t";
236 cout << FGEng1_RPM << " RPM" << "\t";
238 // For a givem Manifold Pressure and RPM calculate the % Power
239 // Multiply Manifold Pressure by RPM
240 ManXRPM = FGEng1_Manifold_Pressure * FGEng1_RPM;
241 cout << ManXRPM << endl;
244 FGEng1_Percentage_Power = (+ 7E-09 * ManXRPM * ManXRPM)
245 + ( + 7E-04 * ManXRPM) - 0.1218;
246 cout << "percent power = " << FGEng1_Percentage_Power << "%" << "\t";
248 // Adjust for Temperature - Temperature above Standard decrease
249 // power % by 7/120 per degree F increase, and incease power for
250 // temps below at the same ratio
251 FGEng1_Percentage_Power = FGEng1_Percentage_Power - (FG_ISA_VAR * 7 /120);
252 cout << " adjusted T = " << FGEng1_Percentage_Power << "%" << "\t";
254 // Adjust for Altitude. In this version a linear variation is
255 // used. Decrease 1% for each 1000' increase in Altitde
256 FGEng1_Percentage_Power = FGEng1_Percentage_Power
257 + (FG_Pressure_Ht * 12/10000);
258 cout << " adjusted A = " << FGEng1_Percentage_Power << "%" << "\t";
260 // Now Calculate Fuel Flow based on % Power Best Power Mixture
261 FGEng1_Fuel_Flow = FGEng1_Percentage_Power
262 * FGEng_Max_Fuel_Flow / 100;
263 // cout << FGEng1_Fuel_Flow << " lbs/hr"<< endl;
265 // Now Derate engine for the effects of Bad/Switched off magnetos
266 if (FGEng1_Magneto_Left == 0 && FGEng1_Magneto_Right == 0) {
267 // cout << "Both OFF\n";
268 FGEng1_Percentage_Power = 0;
269 } else if (FGEng1_Magneto_Left && FGEng1_Magneto_Right) {
270 // cout << "Both On ";
271 } else if (FGEng1_Magneto_Left == 0 || FGEng1_Magneto_Right== 0) {
272 // cout << "1 Magneto Failed ";
274 FGEng1_Percentage_Power = FGEng1_Percentage_Power *
275 ((100 - FGEng_Mag_Derate_Percent)/100);
276 // cout << FGEng1_Percentage_Power << "%" << "\t";
279 // Calculate Engine Horsepower
281 FGEng1_HP = FGEng1_Percentage_Power * FGEng_MaxHP/100;
283 // Calculate Engine Torque
285 FGEng1_Torque = FGEng1_HP * 5252 / FGEng1_RPM;
286 cout << FGEng1_Torque << "Ft/lbs" << "\t";
288 // Calculate Cylinder Head Temperature
289 FGEng1_CHT = CHT (FGEng1_Fuel_Flow, FGEng1_Mixture, IAS);
290 // Show_CHT (FGEng1_CHT);
292 // Calculate Oil Pressure
293 FGEng1_Oil_Pressure = Oil_Press (FGEng1_Oil_Temp, FGEng1_RPM);
294 // Show_Oil_Press(FGEng1_Oil_Pressure);
297 //==============================================================
299 // Now do the Propellor Calculations
302 FGProp1_RPS = FGEng1_RPM * FGEng_Gear_Ratio/60;
303 // cout << FGProp1_RPS << " RPS" << endl;
305 //Radial Flow Vector (V2) Ft/sec at Ref Blade Station (usually 30")
306 FGProp1_Angular_V = FGProp1_RPS * 2 * PI * (Blade_Station / 12);
307 cout << "Angular Velocity " << FGProp1_Angular_V << endl;
309 // Axial Flow Vector (Vo) Ft/sec
310 // Some further work required here to allow for inflow at low speeds
311 // Vo = (IAS + 20) * 1.688888;
312 Vo = IAS_to_FPS(IAS + 20);
315 // cout << Vo << "Axial Velocity" << endl;
317 // Relative Velocity (V1)
318 V1 = sqrt((FGProp1_Angular_V * FGProp1_Angular_V) +
320 cout << "Relative Velocity " << V1 << endl;
322 if ( FGProp1_Blade_Angle >= FGProp_Course_Pitch_Stop ) {
323 FGProp1_Blade_Angle = FGProp_Course_Pitch_Stop;
326 cout << FGProp1_Blade_Angle << " Prop Blade Angle" << endl;
328 // Blade Angle of Attack (Alpha1)
330 Alpha1 = FGProp1_Blade_Angle -(atan(Vo / FGProp1_Angular_V) * (180/PI));
331 // cout << Alpha1 << " Alpha1" << endl;
333 cout << " Alpha1 = " << Alpha1
334 << " Blade angle = " << FGProp1_Blade_Angle
336 << " FGProp1_Angular_V = " << FGProp1_Angular_V << endl;
338 // Calculate Coefficient of Drag at Alpha1
339 FGProp1_Coef_Drag = (0.0005 * (Alpha1 * Alpha1)) + (0.0003 * Alpha1)
341 // cout << FGProp1_Coef_Drag << " Coef Drag" << endl;
343 // Calculate Coefficient of Lift at Alpha1
344 FGProp1_Coef_Lift = -(0.0026 * (Alpha1 * Alpha1)) + (0.1027 * Alpha1)
346 // cout << FGProp1_Coef_Lift << " Coef Lift " << endl;
348 // Covert Alplha1 to Radians
349 // Alpha1 = Alpha1 * PI / 180;
351 // Calculate Prop Torque
352 FGProp1_Torque = (0.5 * Rho * (V1 * V1) * FGProp_Area
353 * ((FGProp1_Coef_Lift * sin(Alpha1 * PI / 180))
354 + (FGProp1_Coef_Drag * cos(Alpha1 * PI / 180))))
355 * (Blade_Station/12);
356 cout << "Prop Torque = " << FGProp1_Torque << endl;
358 // Calculate Prop Thrust
359 FGProp1_Thrust = 0.5 * Rho * (V1 * V1) * FGProp_Area
360 * ((FGProp1_Coef_Lift * cos(Alpha1 * PI / 180))
361 - (FGProp1_Coef_Drag * sin(Alpha1 * PI / 180)));
362 cout << " Prop Thrust = " << FGProp1_Thrust << endl;
364 // End of Propeller Calculations
365 //==============================================================
369 Torque_Imbalance = FGProp1_Torque - FGEng1_Torque;
370 // cout << Torque_Imbalance << endl;
372 if (Torque_Imbalance > 20) {
374 // FGProp1_RPM -= 25;
375 FGProp1_Blade_Angle -= 0.75;
378 if (FGProp1_Blade_Angle < FGProp_Fine_Pitch_Stop) {
379 FGProp1_Blade_Angle = FGProp_Fine_Pitch_Stop;
381 if (Torque_Imbalance < -20) {
383 // FGProp1_RPM += 25;
384 FGProp1_Blade_Angle += 0.75;
387 if (FGEng1_RPM >= 2700) {
392 // cout << FGEng1_RPM << " Blade_Angle " << FGProp1_Blade_Angle << endl << endl;
405 // Calculate Air Density - Rho
406 float Density ( float x )
409 y = ((9E-08 * x * x) - (7E-08 * x) + 0.0024);
413 // Show Air Density Calculations
414 void ShowRho (float x)
424 // Calculate Speed in FPS given Knots CAS
425 float IAS_to_FPS (float x)
432 // Show Feet per Second
433 void ShowFPS (float x)
435 cout << "Feet/sec = ";
441 // Calculate Manifold Pressure based on Throttle lever Position
443 float Manifold_Pressure ( float x, float z)
454 // Show Manifold Pressure
455 void Show_Manifold_Pressure (float x)
457 cout << "Manifold Pressure = ";
461 // Calculate Oil Temperature
463 float Oil_Temp (float Fuel_Flow, float Mixture, float IAS)
470 // Show Oil Temperature
472 void Show_Oil_Temp (float x)
474 cout << "Oil Temperature (F) = ";
479 // Calculate Oil Pressure
481 float Oil_Press (float Oil_Temp, float Engine_RPM)
483 float Oil_Pressure = 0; //PSI
484 float Oil_Press_Relief_Valve = 60; //PSI
485 float Oil_Press_RPM_Max = 1800;
486 float Design_Oil_Temp = 85; //Celsius
487 float Oil_Viscosity_Index = 0.25; // PSI/Deg C
488 float Temp_Deviation = 0; // Deg C
490 Oil_Pressure = (Oil_Press_Relief_Valve / Oil_Press_RPM_Max) * Engine_RPM;
492 // Pressure relief valve opens at Oil_Press_Relief_Valve PSI setting
493 if (Oil_Pressure >= Oil_Press_Relief_Valve)
495 Oil_Pressure = Oil_Press_Relief_Valve;
498 // Now adjust pressure according to Temp which affects the viscosity
500 Oil_Pressure += (Design_Oil_Temp - Oil_Temp) * Oil_Viscosity_Index;
502 return (Oil_Pressure);
506 void Show_Oil_Press (float x)
508 cout << "Oil Pressure (PSI) = ";
514 // Calculate Cylinder Head Temperature
516 float CHT (float Fuel_Flow, float Mixture, float IAS)
523 // Show Cyl Head Temperature
525 void Show_CHT (float x)
527 cout << "CHT (F) = ";