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1 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
2 : :
3 : : Header: FGRocket.h
4 : : Author: Jon S. Berndt
5 : : Date started: 09/12/2000
6 : :
7 : : ------------- Copyright (C) 2000 Jon S. Berndt (jon@jsbsim.org) --------------
8 : :
9 : : This program is free software; you can redistribute it and/or modify it under
10 : : the terms of the GNU Lesser General Public License as published by the Free Software
11 : : Foundation; either version 2 of the License, or (at your option) any later
12 : : version.
13 : :
14 : : This program is distributed in the hope that it will be useful, but WITHOUT
15 : : ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
16 : : FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
17 : : details.
18 : :
19 : : You should have received a copy of the GNU Lesser General Public License along with
20 : : this program; if not, write to the Free Software Foundation, Inc., 59 Temple
21 : : Place - Suite 330, Boston, MA 02111-1307, USA.
22 : :
23 : : Further information about the GNU Lesser General Public License can also be found on
24 : : the world wide web at http://www.gnu.org.
25 : :
26 : : HISTORY
27 : : --------------------------------------------------------------------------------
28 : : 09/12/2000 JSB Created
29 : :
30 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
31 : : SENTRY
32 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
33 : :
34 : : #ifndef FGROCKET_H
35 : : #define FGROCKET_H
36 : :
37 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
38 : : INCLUDES
39 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
40 : :
41 : : #include "FGEngine.h"
42 : : #include "math/FGTable.h"
43 : : #include "input_output/FGXMLElement.h"
44 : :
45 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
46 : : DEFINITIONS
47 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
48 : :
49 : : #define ID_ROCKET "$Id: FGRocket.h,v 1.14 2010/08/21 18:08:25 jberndt Exp $"
50 : :
51 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
52 : : FORWARD DECLARATIONS
53 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
54 : :
55 : : namespace JSBSim {
56 : :
57 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
58 : : CLASS DOCUMENTATION
59 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
60 : :
61 : : /** Models a generic rocket engine.
62 : : The rocket engine is modeled given the following parameters:
63 : : <ul>
64 : : <li>Specific Impulse (in sec)</li>
65 : : </ul>
66 : : Additionally, the following control inputs, operating characteristics, and
67 : : location are required, as with all other engine types:
68 : : <ul>
69 : : <li>Throttle setting (in percent, from 0 to 1.0)</li>
70 : : <li>Maximum allowable throttle setting</li>
71 : : <li>Minimum working throttle setting</li>
72 : : <li>Sea level fuel flow at maximum thrust</li>
73 : : <li>Sea level oxidizer flow at maximum thrust</li>
74 : : <li>X, Y, Z location in structural coordinate frame</li>
75 : : <li>Pitch and Yaw</li>
76 : : </ul>
77 : : The nozzle exit pressure (p2) is returned via a
78 : : call to FGNozzle::GetPowerRequired(). This exit pressure is used
79 : : to get the at-altitude thrust level.
80 : :
81 : : One can model the thrust of a solid rocket by providing a normalized thrust table
82 : : as a function of time. For instance, the space shuttle solid rocket booster
83 : : normalized thrust value looks roughly like this:
84 : :
85 : : <pre>
86 : : \<thrust_table name="propulsion/thrust_time" type="internal">
87 : : \<tableData>
88 : : 0.0 0.00
89 : : 0.2 0.91
90 : : 8.0 0.97
91 : : 16.0 0.99
92 : : 20.0 1.00
93 : : 21.0 1.00
94 : : 24.0 0.95
95 : : 32.0 0.85
96 : : 40.0 0.78
97 : : 48.0 0.72
98 : : 50.0 0.71
99 : : 52.0 0.71
100 : : 56.0 0.73
101 : : 64.0 0.78
102 : : 72.0 0.82
103 : : 80.0 0.81
104 : : 88.0 0.73
105 : : 96.0 0.69
106 : : 104.0 0.59
107 : : 112.0 0.46
108 : : 120.0 0.09
109 : : 132.0 0.00
110 : : \</tableData>
111 : : \</thrust_table>
112 : : </pre>
113 : :
114 : : The left column is time, the right column is normalized thrust. Inside the
115 : : FGRocket class code, the maximum thrust is calculated, and multiplied by this
116 : : table. The Rocket class also tracks burn time. All that needs to be done is
117 : : for the rocket engine to be throttle up to 1. At that time, the solid rocket
118 : : fuel begins burning and thrust is provided.
119 : :
120 : : @author Jon S. Berndt
121 : : $Id: FGRocket.h,v 1.14 2010/08/21 18:08:25 jberndt Exp $
122 : : @see FGNozzle,
123 : : FGThruster,
124 : : FGForce,
125 : : FGEngine,
126 : : FGPropulsion,
127 : : FGTank
128 : : */
129 : :
130 : : /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
131 : : CLASS DECLARATION
132 : : %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
133 : :
134 : : class FGRocket : public FGEngine
135 : : {
136 : : public:
137 : : /** Constructor.
138 : : @param exec pointer to JSBSim parent object, the FDM Executive.
139 : : @param el a pointer to the XML Element instance representing the engine.
140 : : @param engine_number engine number */
141 : : FGRocket(FGFDMExec* exec, Element *el, int engine_number);
142 : :
143 : : /** Destructor */
144 : : ~FGRocket(void);
145 : :
146 : : /** Determines the thrust.*/
147 : : void Calculate(void);
148 : :
149 : : /** Gets the total impulse of the rocket.
150 : : @return The cumulative total impulse of the rocket up to this time.*/
151 : 12 : double GetTotalImpulse(void) const {return It;}
152 : :
153 : : /** Gets the flame-out status.
154 : : The engine will "flame out" if the throttle is set below the minimum
155 : : sustainable-thrust setting.
156 : : @return true if engine has flamed out. */
157 : : bool GetFlameout(void) {return Flameout;}
158 : :
159 : 10 : double GetOxiFlowRate(void) const {return OxidizerFlowRate;}
160 : :
161 : : std::string GetEngineLabels(const std::string& delimiter);
162 : : std::string GetEngineValues(const std::string& delimiter);
163 : :
164 : : /** Sets the thrust variation for a solid rocket engine.
165 : : Solid propellant rocket motor thrust characteristics are typically
166 : : defined at 70 degrees F temperature. At any other temperature,
167 : : performance will be different. Warmer propellant grain will
168 : : burn quicker and at higher thrust. Total motor impulse is
169 : : not changed for change in thrust.
170 : : @param var the variation in percent. That is, a 2 percent
171 : : variation would be specified as 0.02. A positive 2% variation
172 : : in thrust would increase the thrust by 2%, and shorten the burn time. */
173 : 0 : void SetThrustVariation(double var) {ThrustVariation = var;}
174 : :
175 : : /** Sets the variation in total motor energy.
176 : : The total energy present in a solid rocket motor can be modified
177 : : (such as might happen with manufacturing variations) by setting
178 : : the total Isp variation.
179 : : @param var the variation in percent. That is, a 2 percent
180 : : variation would be specified as 0.02. This variation will
181 : : affect the total thrust, but not the burn time.*/
182 : 0 : void SetTotalIspVariation(double var) {TotalIspVariation = var;}
183 : :
184 : : /** Returns the thrust variation, if any. */
185 : 2 : double GetThrustVariation(void) const {return ThrustVariation;}
186 : :
187 : : /** Returns the Total Isp variation, if any. */
188 : 2 : double GetTotalIspVariation(void) const {return TotalIspVariation;}
189 : :
190 : : private:
191 : : /** Reduces the fuel in the active tanks by the amount required.
192 : : This function should be called from within the
193 : : derived class' Calculate() function before any other calculations are
194 : : done. This base class method removes fuel from the fuel tanks as
195 : : appropriate, and sets the starved flag if necessary. */
196 : : void ConsumeFuel(void);
197 : :
198 : : /** The fuel need is calculated based on power levels and flow rate for that
199 : : power level. It is also turned from a rate into an actual amount (pounds)
200 : : by multiplying it by the delta T and the rate.
201 : : @return Total fuel requirement for this engine in pounds. */
202 : : double CalcFuelNeed(void);
203 : :
204 : : /** The oxidizer need is calculated based on power levels and flow rate for that
205 : : power level. It is also turned from a rate into an actual amount (pounds)
206 : : by multiplying it by the delta T and the rate.
207 : : @return Total oxidizer requirement for this engine in pounds. */
208 : : double CalcOxidizerNeed(void);
209 : :
210 : : /** Returns the vacuum thrust.
211 : : @return The vacuum thrust in lbs. */
212 : 12 : double GetVacThrust(void) const {return VacThrust;}
213 : :
214 : : void bindmodel(void);
215 : :
216 : : double Isp; // Vacuum Isp
217 : : double It;
218 : : double MxR; // Mixture Ratio
219 : : double BurnTime;
220 : : double ThrustVariation;
221 : : double TotalIspVariation;
222 : : double VacThrust;
223 : : double previousFuelNeedPerTank;
224 : : double previousOxiNeedPerTank;
225 : : double OxidizerExpended;
226 : : double SLOxiFlowMax;
227 : : double OxidizerFlowRate;
228 : : double PropellantFlowRate;
229 : : bool Flameout;
230 : : double BuildupTime;
231 : : FGTable* ThrustTable;
232 : :
233 : : void Debug(int from);
234 : : };
235 : : }
236 : : //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
237 : : #endif
238 : :
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