Hide keyboard shortcuts

Hot-keys on this page

r m x p   toggle line displays

j k   next/prev highlighted chunk

0   (zero) top of page

1   (one) first highlighted chunk

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69

70

71

72

73

74

75

76

77

78

79

80

81

82

83

84

85

86

87

88

89

90

91

92

93

94

95

96

97

98

99

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

152

153

154

155

156

157

158

159

160

161

162

163

164

165

166

167

168

169

170

171

172

173

174

175

176

177

178

179

180

181

182

183

184

185

186

187

188

189

190

191

192

193

194

195

196

197

198

199

200

201

202

203

204

205

206

207

208

209

210

211

212

213

214

215

216

217

218

219

220

221

222

223

224

225

226

227

228

229

230

231

232

233

234

235

236

237

238

239

240

241

242

243

244

245

246

247

248

249

250

251

252

253

254

255

256

257

258

259

260

261

262

263

264

265

266

267

268

269

270

271

272

273

274

275

276

277

278

279

280

281

282

283

284

285

286

287

288

289

290

291

292

293

294

295

296

297

298

299

300

301

302

303

304

305

306

307

308

309

310

311

312

313

314

315

316

317

318

319

320

321

322

323

324

325

326

327

328

329

330

331

332

333

334

335

336

337

338

339

340

341

342

343

344

345

346

from math import log, exp, log10 

from rocketcea.Goal import Goal 

 

gc = 32.174 

 

 

def getRhoVeh( volCuIn ): 

"""Generic equation for scaling stage mass by volume""" 

if volCuIn <=1.0E-8: 

print( 'ERROR in volCuIn in getRhoVeh; volCuIn=',volCuIn ) 

volCuIn = 1.0E-8 # for volume<=0 reset volume tiny so calculated rhoveh is terrible. 

 

expon = (log10(volCuIn) + 1.)/(-3.) 

rhoveh = 10.0**expon 

return rhoveh 

 

 

 

class ReferenceStage: 

'''Scale reference stage to new propellant volume using getRhoVeh correlation''' 

 

def calc_rhoVeh(self, vol): 

return self.corrFactor * getRhoVeh( vol ) 

 

@property 

def MassFrac(self): 

try: 

mf = self.WtPropellant / (self.WtPropellant + self.WtInert) 

except: 

mf = 0.0 

return mf 

 

def __init__(self, WtPayload=1600000.0, volCuInRef=75500.0*1728, WtInertRef=300000.0, 

Name='Saturn V 1st stg'): 

 

self.stage_desc = "Wpayload=%g lbm, Mass Scaled from: %s"%(WtPayload, Name) 

self.Name = Name 

 

rhoVeh = WtInertRef / volCuInRef 

corrRhoStg = getRhoVeh( volCuInRef ) 

self.corrFactor = rhoVeh / corrRhoStg 

 

self.WtPayload = WtPayload 

 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

 

def setGLOW(self, GLOW=5000.0, sg=1.0, Isp=300.0): 

 

self.GLOW = GLOW 

rho = sg * 0.0361273 

 

def calc_glow_from_vol( V ): 

rhoStg = self.calc_rhoVeh(V) 

return V*(rhoStg + rho) + self.WtPayload 

 

G = Goal(goalVal=GLOW, minX=0.01, maxX=(GLOW-self.WtPayload)/rho, verbose=False, 

funcOfX=calc_glow_from_vol, tolerance=1.0E-10, maxLoops=80, failValue=None) 

self.VolPropellant, ierror = G() 

 

if ierror: 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

else: 

self.WtPropellant = rho * self.VolPropellant 

self.WtInert = self.GLOW - self.WtPropellant - self.WtPayload 

Wbo = self.WtPayload + self.WtInert 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

 

 

def setWtInert(self, WtInert=1000.0, sg=1.0, Isp=300.0): 

 

self.WtInert = WtInert 

rho = sg * 0.0361273 

 

def calc_winert_from_vol( V ): 

rhoStg = self.calc_rhoVeh(V) 

return V * rhoStg 

 

G = Goal(goalVal=WtInert, minX=0.01, maxX=99.99*WtInert/rho, verbose=False, 

funcOfX=calc_winert_from_vol, tolerance=1.0E-10, maxLoops=80, failValue=None) 

self.VolPropellant, ierror = G() 

if ierror: 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

else: 

 

self.WtPropellant = rho * self.VolPropellant 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

 

def setWtPropellant(self, WtPropellant=1000.0, sg=1.0, Isp=300.0): 

 

self.WtPropellant = WtPropellant 

rho = sg * 0.0361273 

self.VolPropellant = WtPropellant / rho 

 

rhoVeh = self.calc_rhoVeh( self.VolPropellant ) 

self.WtInert = rhoVeh * self.VolPropellant 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

 

def setVolPropellant(self, VolPropellant=10000.0, sg=1.0, Isp=300.0): 

 

self.VolPropellant = VolPropellant 

rho = sg * 0.0361273 

self.WtPropellant = rho * VolPropellant 

 

rhoVeh = self.calc_rhoVeh( self.VolPropellant ) 

self.WtInert = rhoVeh * self.VolPropellant 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

def setDeltaV(self, DeltaV=2000.0, sg=1.0, Isp=300.0): 

 

self.DeltaV = DeltaV 

rho = sg * 0.0361273 

 

def calc_dv_from_vol( V ): 

rhoStg = self.calc_rhoVeh(V) 

glow = V*(rhoStg + rho) + self.WtPayload 

wbo = glow - V*rho 

return gc * Isp * log( glow/wbo ) 

 

gam = DeltaV / Isp / gc 

glow = self.WtPayload * 1000.0 * exp(gam) 

 

G = Goal(goalVal=DeltaV, minX=0.01, maxX=glow/rho, verbose=False, 

funcOfX=calc_dv_from_vol, tolerance=1.0E-10, maxLoops=80, failValue=None) 

self.VolPropellant, ierror = G() 

if ierror: 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

else: 

 

self.WtPropellant = rho * self.VolPropellant 

 

rhoVeh = self.calc_rhoVeh( self.VolPropellant ) 

self.WtInert = rhoVeh * self.VolPropellant 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

 

 

def summ_print(self): 

 

try: 

print('Wp=%g, Vp=%g, Winert=%g, dv=%g, GLOW=%g, mu=%g'%\ 

(self.WtPropellant, self.VolPropellant, self.WtInert, self.DeltaV, self.GLOW, self.MassFrac)) 

except: 

print('Wp=%s, Vp=%s, Winert=%s, dv=%s, GLOW=%s, mu=%s'%\ 

(self.WtPropellant, self.VolPropellant, self.WtInert, self.DeltaV, self.GLOW, self.MassFrac)) 

 

 

class ReferenceStagePair( ReferenceStage ): 

'''Scale reference stage pair to new propellant volume using getRhoVeh correlation''' 

def calc_rhoVeh(self, vol): 

 

vrat = (log10(vol)-log10(self.volCuIn2))/ (log10(self.volCuIn1)-log10(self.volCuIn2)) 

logRV = log10(self.rhoVeh2) + vrat*(log10(self.rhoVeh1)-log10(self.rhoVeh2)) 

rhoVeh = 10.0**logRV 

 

return rhoVeh 

 

def __init__(self, Name='N2H4 DACS', WtPayload=30.0, 

volCuIn1=463.58, WtInert1=18.1563, 

volCuIn2=192.23, WtInert2=15.28557): 

 

self.stage_desc = "Wpayload=%g lbm, Stage Pair from: %s"%(WtPayload, Name) 

self.WtPayload = WtPayload 

 

self.volCuIn1 = volCuIn1 

self.WtInert1 = WtInert1 

self.volCuIn2 = volCuIn2 

self.WtInert2 = WtInert2 

self.Name = Name 

 

self.rhoVeh1 = WtInert1 / volCuIn1 

self.corrRhoStg1 = getRhoVeh( volCuIn1 ) 

 

self.rhoVeh2 = WtInert2 / volCuIn2 

self.corrRhoStg2 = getRhoVeh( volCuIn2 ) 

 

self.corrFactor1 = self.rhoVeh1 / self.corrRhoStg1 

self.corrFactor2 = self.rhoVeh2 / self.corrRhoStg2 

 

 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

 

 

class ConstMassFracStage: 

"""Assumes all propellants can achieve the same stage propellant mass fraction (A BAD ASSUMPTION)""" 

 

def __init__(self, mass_frac=0.8, WtPayload=1000.0): 

 

self.stage_desc = "Wpayload=%g lbm, Mass Fraction=%g (A BAD ASSUMPTION)"%(WtPayload, mass_frac) 

 

self.mass_frac = mass_frac 

self.WtPayload = WtPayload 

 

self.WtInert = None 

self.WtPropellant = None 

self.VolPropellant = None # cuin 

self.DeltaV = None 

self.GLOW = None # includes payload mass 

 

@property 

def MassFrac(self): 

try: 

mf = self.WtPropellant / (self.WtPropellant + self.WtInert) 

except: 

mf = 0.0 

return mf 

 

def setGLOW(self, GLOW=5000.0, sg=1.0, Isp=300.0): 

 

self.GLOW = GLOW 

WstgIgn = self.GLOW - self.WtPayload 

 

self.WtPropellant = WstgIgn * self.mass_frac 

self.WtInert = WstgIgn - self.WtPropellant 

rho = sg * 0.0361273 

self.VolPropellant = self.WtPropellant / rho 

 

Wbo = self.WtPayload + self.WtInert 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

def setWtInert(self, WtInert=1000.0, sg=1.0, Isp=300.0): 

 

self.WtInert = WtInert 

self.WtPropellant = self.mass_frac * WtInert / (1.0-self.mass_frac) 

 

rho = sg * 0.0361273 

self.VolPropellant = self.WtPropellant / rho 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

 

def setWtPropellant(self, WtPropellant=1000.0, sg=1.0, Isp=300.0): 

 

self.WtPropellant = WtPropellant 

self.WtInert = WtPropellant * (1.0-self.mass_frac) / self.mass_frac 

 

rho = sg * 0.0361273 

self.VolPropellant = self.WtPropellant / rho 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

 

def setVolPropellant(self, VolPropellant=10000.0, sg=1.0, Isp=300.0): 

 

self.VolPropellant = VolPropellant 

 

rho = sg * 0.0361273 

self.WtPropellant = VolPropellant * rho 

self.WtInert = self.WtPropellant * (1.0-self.mass_frac) / self.mass_frac 

 

Wbo = self.WtPayload + self.WtInert 

self.GLOW = Wbo + self.WtPropellant 

self.DeltaV = gc * Isp * log( self.GLOW/Wbo ) 

 

def setDeltaV(self, DeltaV=2000.0, sg=1.0, Isp=300.0): 

 

self.DeltaV = DeltaV 

rho = sg * 0.0361273 

 

gam = DeltaV / Isp / gc 

mu = self.mass_frac 

 

self.GLOW = self.WtPayload * mu / ( exp(-gam) - (1.0-mu) ) 

WstgIgn = self.GLOW - self.WtPayload 

 

self.WtPropellant = WstgIgn * mu 

self.WtInert = WstgIgn - self.WtPropellant 

self.VolPropellant = self.WtPropellant / rho 

 

def summ_print(self): 

 

try: 

print('mf=%g, Wp=%g, Vp=%g, Winert=%g, dv=%g, GLOW=%g, mu=%g'%\ 

(self.mass_frac, self.WtPropellant, self.VolPropellant, self.WtInert, self.DeltaV, self.GLOW, self.MassFrac)) 

except: 

print('mf=%g, Wp=%s, Vp=%s, Winert=%s, dv=%s, GLOW=%s, mu=%s'%\ 

(self.mass_frac, self.WtPropellant, self.VolPropellant, self.WtInert, self.DeltaV, self.GLOW, self.MassFrac)) 

 

 

 

 

if __name__=="__main__": 

 

if 1: 

#cmf = ConstMassFracStage() 

cmf = ReferenceStage() 

cmf.summ_print() 

cmf.setWtInert( WtInert=1000.0 ) 

else: 

cmf = ReferenceStagePair() 

cmf.summ_print() 

cmf.setWtInert( WtInert=15.28557 ) 

 

cmf.summ_print() 

wp = cmf.WtPropellant 

vol = cmf.VolPropellant 

dv = cmf.DeltaV 

glow = cmf.GLOW 

 

cmf.setWtPropellant( WtPropellant=wp ) 

cmf.summ_print() 

 

cmf.setVolPropellant( VolPropellant=vol ) 

cmf.summ_print() 

 

cmf.setDeltaV( DeltaV=dv) 

cmf.summ_print() 

 

cmf.setGLOW( GLOW=glow) 

cmf.summ_print()