Shuttle OMS | |
| RocketIsp version 0.1.12 | Sunday, Jul 19, 2026 at 09:15AM |
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N2O4/MMH IspVac = 315.297 sec MRcore = 1.83333 MRthruster = 1.65 Rt = 2.90533 in At = 26.5179 in**2 Pc = 125 psia Fvac = 6000 lbf cham_freq = 4343.56 Hz (2T=4485 Hz) Nelements = 276 (set by acoustics) elemDens = 3.9046 elem/in**2 DorfOx = 0.0456 in DorfFuel = 0.0401 in |
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| Geometry |
|---|
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| cham_conv_deg = | 30.00 deg | half angle of conical convergent section | |
| CR = | 2.5 | chamber contraction ratio (Ainj / Athroat) | |
| eps = | 55 | nozzle area ratio (Aexit / Athroat) | |
| LchamberInp = | None in | user input value of chamber length (will override all other entries) | |
| LchmMin = | 2.000 in |
5.080 cm 0.167 ft |
minimum chamber length (will override LchmOvrDt) |
| LchmOvrDt = | 3.1 | ratio of chamber length to throat diameter (Lcham / Dthrt) | |
| LnozInp = | None in | user input nozzle length (will override pcentBell) | |
| pcentBell = | 80 | nozzle percent bell (Lnoz / L_15deg_cone) | |
| RchmConv = | 1 | radius of curvature at start of convergent section (Rconv / Rthrt) | |
| RdwnThroat = | 1 | radius of curvature just downstream of throat (Rdownstream / Rthrt) | |
| Rthrt = | 2.905 in |
7.380 cm 0.242 ft |
throat radius |
| RupThroat = | 1.5 | radius of curvature just upstream of throat (Rupstream / Rthrt) | |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| Ainj = | 66.295 in**2 | 427.708 cm**2 | area of injector |
| At = | 26.518 in**2 | 171.083 cm**2 | throat area |
| Dexit = | 43.093 in |
109.456 cm 3.591 ft |
nozzle exit diameter |
| Dinj = | 9.187 in |
23.336 cm 0.766 ft |
diameter of injector |
| Dthrt = | 5.811 in |
14.759 cm 0.484 ft |
throat diameter |
| entrance_angle = | 34.79 deg | nozzle initial expansion angle | |
| exit_angle = | 7.70 deg | nozzle exit angle | |
| Lcham_conv = | 4.871 in |
12.371 cm 0.406 ft |
length of convergent section of chamber |
| Lcham_cyl = | 13.142 in |
33.382 cm 1.095 ft |
length of cylindrical section of chamber |
| Lnoz = | 55.656 in |
141.366 cm 4.638 ft |
nozzle length |
| Ltotal = | 73.669 in |
187.119 cm 6.139 ft |
nozzle + chamber length |
| Rinj = | 4.594 in |
11.668 cm 0.383 ft |
radius of injector |
| Vcham = | 1090.0 in**3 | 17862.4 cm**3 | approximate chamber volume |
| N2O4/MMH Core Stream Tube |
|---|
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| adjCstarODE = | 1 | multiplier on NASA CEA code value of cstar ODE (default is 1.0) | |
| adjIspIdeal = | 1 | multiplier on NASA CEA code value of Isp ODE (default is 1.0) | |
| CdThroat = | 0.989746 |
Cd of throat (RocketThruster object may override) (MLP fit) |
|
| fuelName = | MMH | name of fuel (e.g. MMH, LH2) | |
| ignore_noz_sep = | 0 | flag to force nozzle flow separation to be ignored (USE WITH CAUTION) | |
| MRcore = | 1.83333 | mixture ratio of core flow (ox flow rate / fuel flow rate) | |
| oxName = | N2O4 | name of oxidizer (e.g. N2O4, LOX) | |
| Pamb = | 0.00 psia |
0.00 MPa 0.00 atm 0.00 bar |
ambient pressure (for example sea level is 14.7 psia) |
| Pc = | 125.0 psia |
0.86 MPa 8.51 atm 8.62 bar |
chamber pressure |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| CfAmbDel = | 1.8101 | delivered ambient thrust coefficient | |
| CfVacDel = | 1.8101 | delivered vacuum thrust coefficient | |
| CfVacIdeal = | 1.91514 | ideal vacuum thrust coefficient | |
| cstarERE = | 5572.5 ft/s | 1698.5 m/s | delivered core cstar |
| cstarODE = | 5693.3 ft/s | 1735.3 m/s | core ideal cstar |
| FvacBarrier = | 1648.5 lbf | 7333.0 N | vacuum thrust due to barrier stream tube |
| FvacCore = | 4351.5 lbf | 19356.3 N | vacuum thrust due to core stream tube |
| FvacTotal = | 6000.0 lbf | 26689.3 N | total vacuum thrust |
| gammaChm = | 1.14074 | core gas ratio of specific heats (Cp/Cv) | |
| IspDel = | 315.30 sec |
3092.01 N-sec/kg 3.09 km/sec |
<=== thruster delivered vacuum Isp ===> |
| IspDel_core = | 319.25 sec |
3130.79 N-sec/kg 3.13 km/sec |
delivered Isp of core stream tube |
| IspODE = | 338.89 sec |
3323.37 N-sec/kg 3.32 km/sec |
core one dimensional equilibrium Isp |
| IspODF = | 318.56 sec |
3123.99 N-sec/kg 3.12 km/sec |
core frozen Isp |
| IspODK = | 331.08 sec |
3246.80 N-sec/kg 3.25 km/sec |
core one dimensional kinetic Isp |
| MRthruster = | 1.65 | total thruster mixture ratio') | |
| MWchm = | 21.211 g/gmole | core gas molecular weight | |
| Pexit = | 0.1606 psia |
0.00 MPa 0.01 atm 0.01 bar |
nozzle exit pressure |
| TcODE = | 5612.0 degR |
3117.8 degK 2844.6 degC 5152.3 degF |
ideal core gas temperature |
| wdotFl = | 7.181 lbm/s | 3.257 kg/s | total fuel flow rate |
| wdotOx = | 11.849 lbm/s | 5.374 kg/s | total oxidizer flow rate |
| wdotTot = | 19.030 lbm/s | 8.632 kg/s | total propellant flow rate (ox+fuel) |
| At Injector Face | |||
| Parameter = | Value | Alt Value | Description |
| wdotFl_cInit = | 6.463 lbm/s | 2.932 kg/s | initial core fuel flow rate (before any entrainment) |
| wdotFlFFC = | 0.718 lbm/s | 0.326 kg/s | fuel film coolant flow rate injected at perimeter |
| wdotTot_cInit = | 18.312 lbm/s | 8.306 kg/s | initial core total flow rate (before any entrainment) |
| After Entrainment | |||
| Parameter = | Value | Alt Value | Description |
| wdotFl_b = | 2.370 lbm/s | 1.075 kg/s | barrier fuel flow rate (FFC + entrained) |
| wdotFl_c = | 4.811 lbm/s | 2.182 kg/s | final core fuel flow rate (injected - entrained) |
| wdotOx_b = | 3.029 lbm/s | 1.374 kg/s | barrier oxidizer flow rate (all entrained) |
| wdotOx_c = | 8.820 lbm/s | 4.000 kg/s | final core oxidizer flow rate (injected - entrained) |
| wdotTot_b = | 5.399 lbm/s | 2.449 kg/s | total barrier propellant flow rate (includes entrained) |
| wdotTot_c = | 13.630 lbm/s | 6.183 kg/s | total final core propellant flow rate (injected - entrained) |
| Efficiencies |
|---|
| Output | ||
|---|---|---|
| Parameter = | Value | Description |
| Isp = | 0.93038 | Overall Isp Efficiency |
| Noz = | 0.96247 | Nozzle Efficiency |
| ERE = | 0.97878 | Energy Release Efficiency of Chamber |
| FFC = | 0.98761 | (barrier calc) Fuel Film Cooling Efficiency of Chamber |
| Nozzle | ||
| Parameter = | Value | Description |
| Div = | 0.99303 | (simple fit eps=55, %bell=80) Divergence Efficiency of Nozzle |
| Kin = | 0.97696 | (MLP fit) Kinetic Efficiency of Nozzle |
| BL = | 0.99208 | (MLP fit) Boundary Layer Efficiency of Nozzle |
| Chamber | ||
| Parameter = | Value | Description |
| Mix = | 0.99494 | (mixAngle=1.42 deg) Inter-Element Mixing Efficiency of Injector |
| Em = | 0.98537 | (Rupe elemEm=0.8) Intra-Element Mixing Efficiency of Injector |
| Vap = | 0.99837 | (gen vaporized length) Vaporization Efficiency of Injector |
| Ignored Efficiencies |
|---|
| TP: Two Phase Efficiency of Nozzle |
| HL: Heat Loss Efficiency of Chamber |
| Barrier Stream Tube |
|---|
| Input | ||
|---|---|---|
| Parameter = | Value | Description |
| ko = | 0.035 | entrainment constant (typical value is 0.035, range from 0.03 to 0.06) |
| pcentFFC = | 10 | percent fuel film cooling ( FFC flowrate / total fuel flowrate) |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| cstarERE_b = | 5482.1 ft/s | 1671.0 m/s | delivered cstar |
| cstarODE_b = | 5601.0 ft/s | 1707.2 m/s | ideal equilibrium cstar |
| fracEntr = | 0.25565 | fraction of core flow entrained into barrier | |
| fracKin_b = | 0.389259 | fraction of kinetic completion in barrier | |
| IspDel_b = | 305.31 sec |
2994.10 N-sec/kg 2.99 km/sec |
delivered vacuum barrier Isp |
| IspODE_b = | 321.319 | sec. ideal equilibrium barrier Isp | |
| IspODF_b = | 313.64 sec |
3075.72 N-sec/kg 3.08 km/sec |
ideal frozen barrier Isp |
| IspODK_b = | 316.63 sec |
3105.05 N-sec/kg 3.11 km/sec |
vacuum kinetic Isp of barrier |
| MRbarrier = | 1.27792 | barrier mixture ratio at throat | |
| MRwall = | 0.860525 | mixture ratio at throat wall | |
| TcODE_b = | 4933.1 degR |
2740.6 degK 2467.4 degC 4473.4 degF |
average ideal ODE temperature of barrier gas |
| Twallgas = | 3786.1 degR |
2103.4 degK 1830.3 degC 3326.5 degF |
temperature of gas at throat wall (cooler upstream) |
| WentrOvWcool = | 6.51908 | ratio of entrained flow rate to FFC flow rate | |
| N2O4/MMH Injector |
|---|
| Assumptions |
|---|
| NOTE: Injector elements are designed by Initial Core Flow ONLY. |
| Fuel Film Cooling orifices must be designed separately. |
| NOTE: number of elements set by acoustics |
| Acoustic frequency set by 2T |
| Fuel Orifice Diameter Meets Stability Requirement of >= 40.1 mil |
| Chamber design frequency set by: acoustics to: 4344 Hz, (2T=4485 Hz) |
| Input | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| desAcousMode = | 2T | driving acoustic mode of injector OR acoustic mode multiplier (setNelementsBy=="acoustics" and setAcousticFreqBy=="mode") | |
| DorfMin = | 0.0080 in |
8.000 mil 0.203 mm |
minimum orifice diameter (lower limit) |
| elemEm = | 0.8 | intra-element Rupe mixing factor (0.7 below ave, 0.8 ave, 0.9 above ave) | |
| setAcousticFreqBy = | mode | flag indicating how to determine design frequency. (can be "mode" or "freq") | |
| setNelementsBy = | acoustics | flag determines how to calculate number of elements ( "acoustics", "elem_density", "input") | |
| Ox Properties | |||
| Parameter = | Value | Alt Value | Description |
| CdOxOrf = | 0.75 | flow coefficient of oxidizer orifices | |
| dropCorrOx = | 0.33 | oxidizer drop size multiplier (showerhead=3.0, like-doublet=1.0, vortex=0.5, unlike-doublet=0.33) | |
| fdPinjOx = | 0.25 | fraction of Pc used as oxidizer injector pressure drop | |
| LfanOvDorfOx = | 20 | fan length / oxidizer orifice diameter | |
| OxOrfPerEl = | 1 | number of oxidizer orifices per element | |
| Tox = | 530.0 degR |
294.4 degK 21.3 degC 70.3 degF |
temperature of oxidizer |
| Fuel Properties | |||
| Parameter = | Value | Alt Value | Description |
| CdFuelOrf = | 0.75 | flow coefficient of fuel orifices | |
| dropCorrFuel = | 0.33 | fuel drop size multiplier (showerhead=3.0, like-doublet=1.0, vortex=0.5, unlike-doublet=0.33) | |
| fdPinjFuel = | 0.25 | fraction of Pc used as fuel injector pressure drop | |
| FuelOrfPerEl = | 1 | number of fuel orifices per element | |
| LfanOvDorfFuel = | 20 | fan length / fuel orifice diameter | |
| lolFuelElem = | 0 | flag for like-on-like fuel element (determines strouhal multiplier) | |
| Tfuel = | 530.0 degR |
294.4 degK 21.3 degC 70.3 degF |
temperature of fuel |
| Output | |||
|---|---|---|---|
| Parameter = | Value | Alt Value | Description |
| des_freq = | 4343.6 Hz | chamber design acoustic frequency | |
| DorfFlForHzLimit = | 0.040 in |
40.138 mil 1.019 mm |
fuel orifice Diameter for frequency in Hewitt Correlation |
| elemDensCalc = | 3.905 elem/in**2 | 0.605 elem/cm**2 | element density on injector face |
| Nelements = | 276 | number of elements on injector face | |
| NelemMakable = | 6948 | maximum number of makable elements giving correct flow rate (diam=DorfMin) | |
| Ox Properties | |||
| Parameter = | Value | Alt Value | Description |
| AfloOx = | 0.450 in**2 | 2.906 cm**2 | total flow area of oxidizer |
| dHvapOx = | 177.52 BTU/lbm |
98.69 cal/g 412.91 J/g |
oxidizer heat of vaporization |
| DorfOx = | 0.0456 in |
45.584 mil 1.158 mm |
oxidizer orifice diameter |
| dpOx = | 31.25 psid |
0.22 MPa 2.13 atm 2.15 bar |
oxidizer injector pressure drop |
| MolWtOx = | 92.011 g/gmole | oxidizer molecular weight | |
| NOxOrf = | 276 | number of oxidizer orifices on injector face | |
| sgOx = | 1.439 g/ml |
0.052 lbm/inch**3 89.823 lbm/ft**3 |
oxidizer density |
| surfOx = | 1.483e-04 lbf/in |
2.598e-02 N/m 2.598e+01 mN/m 2.598e+01 dyne/cm |
oxidizer surface tension |
| velOx_fps = | 56.8 ft/s | 17.3 m/s | velocity of injected oxidizer |
| viscOx = | 2.777e-04 poise |
2.777e-02 cpoise 2.777e-05 Pa*s 6.718e-02 lbm/hr/ft |
oxidizer viscosity |
| Fuel Properties | |||
| Parameter = | Value | Alt Value | Description |
| AfloFuel = | 0.349 in**2 | 2.253 cm**2 | total flow area of fuel |
| dHvapFuel = | 376.36 BTU/lbm |
209.23 cal/g 875.41 J/g |
fuel heat of vaporization |
| DorfFuel = | 0.0401 in |
40.141 mil 1.020 mm |
fuel orifice diameter |
| dpFuel = | 31.25 psid |
0.22 MPa 2.13 atm 2.15 bar |
fuel injector pressure drop |
| MolWtFuel = | 46.072 g/gmole | fuel molecular weight | |
| NFuelOrf = | 276 | number of fuel orifices on injector face | |
| sgFuel = | 0.879 g/ml |
0.032 lbm/inch**3 54.866 lbm/ft**3 |
fuel density |
| surfFuel = | 1.951e-04 lbf/in |
3.417e-02 N/m 3.417e+01 mN/m 3.417e+01 dyne/cm |
fuel surface tension |
| velFuel_fps = | 72.6 ft/s | 22.1 m/s | velocity of injected fuel |
| viscFuel = | 5.534e-04 poise |
5.534e-02 cpoise 5.534e-05 Pa*s 1.339e-01 lbm/hr/ft |
fuel viscosity |
| Vaporization | |||
| Parameter = | Value | Alt Value | Description |
| chamShapeFact = | 0.6775 | chamber shape factor | |
| fracVapFuel = | 0.9952 | fraction of vaporized fuel | |
| fracVapOx = | 0.9998 | fraction of vaporized oxidizer | |
| genVapLenFuel = | 51.90 | Priem generalized vaporization length of fuel | |
| genVapLenOx = | 150.86 | Priem generalized vaporization length of oxidizer | |
| mrVap = | 1.8418 | vaporized mixture ratio | |
| rDropFuel = | 0.7558 mil |
19.20 micron 0.02 mm |
median fuel droplet radius |
| rDropOx = | 0.5963 mil |
15.15 micron 0.02 mm |
median ox droplet radius |
| Combustion Stability | |||
| Parameter = | Value | Alt Value | Description |
| cham sonicVel = | 3532.3 ft/s | 1076.7 m/s | approximate gas sonic velocity in chamber |
| fdPinjFuelReqd = | 0.137341 | minimum required fuel dP/Pc | |
| fdPinjOxReqd = | 0.184428 | minimum required oxidizer dP/Pc | |
| tauFuel = | 0.920903 ms | fuel lag time (tau/tResid=0.608969) | |
| tauOx = | 1.33807 ms | oxidizer lag time (tau/tResid=0.884827) | |
| tResid = | 1.5122 ms | residual time in chamber | |
| Acoustic Modes | |||
| Parameter = | Value | Alt Value | Description |
| 1L = | 1176 Hz | ||
| 80% of 1T = | 2163 Hz | no damping required here | |
| 1T = | 2704 Hz | ||
| =====> DESIGN = | 4343 Hz | <== DESIGN IS HERE | |
| 2T = | 4485 Hz | ||
| 80% of 1R = | 4501 Hz | baffles-only work here | |
| 80% of 3T = | 4935 Hz | cavities-only work here | |
| 1R = | 5627 Hz | ||
| 3T = | 6169 Hz | baffles + cavities OR multi-tuned cavities | |
| 3T = | 6169 Hz | <== MAX FREQUENCY... KEEP Hz HERE OR BELOW | |
| 4T = | 7809 Hz | ||
| 1T1R = | 7829 Hz | ||
| 2T1R = | 9848 Hz | ||
| 2R = | 10302 Hz | ||
| 3T1R = | 11770 Hz | ||
| 1T2R = | 12521 Hz | ||