16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 1 of 12 16.522, Space Propulsion Prof. Manuel Martinez-Sanchez Lecture 7: Bipropellant Chemical Thrusters and Chemical Propulsion Systems Considerations (Valving, tanks, etc) Characteristics of some monopropellants (Reprinted from H. Koelle, Handbook of Astronautical Engineering, McGraw-Hill, 1961.) Flame Chemical Density temp, F D C * ,fps I sp ,S Sensitivity Nitromethane 1.13 4002 5026 244 Yes Nitroglycerine 1.60 5496 4942 244 Yes Ethyl nitrate 1.10 3039 4659 224 Yes Hydrazine 1.01 2050 3952 230 No Tetronitromethane 1.65 3446 3702 180 Yes Hydrogen peroxide 1.45 1839 3418 165 No Ethylene oxide 0.87 1760 3980 189 No n-Propyl nitrate 1.06 2587 4265 201 Yes 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 2 of 12 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 3 of 12 Thruster Weight A least-square curve fit of the weight of nine different thruster/valve designs with thrust levels from 1 to 150 lb produces the following relation: 0.55235 = 0.34567 t WF The figure above shows the correlation; the correlation coefficient is 0.97. For low thrust levels, the thruster weight approaches the valve weight, an effect that Equation (4.5) will not predict. Use 0.4lb as a minimum thruster/valve weight for low thrust levels. Note that figure above is for a thruster with single valves. 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 4 of 12 1) Capillary devices, which use surface tension forces to keep gas and liquid separated. These are particularly useful for bipropellant systems like the space Shuttle and Viking Orbiter because they are compatible with strong oxidizers. 2) Diaphragms and bladders, which are physical separation devices made of elastomer or Teflon. These are used by Voyager, Mariner 71, and Magellan. Elastomer types are not compatible with oxidizers. 3) Bellows, a metal separation device, used by Minuteman. 4) Traps, a check valve protected compartment, used by Transtage. 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 5 of 12 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 6 of 12 Image adapted from: SPACECRAFT PROPULSION, by Ch. D. Brown AIAA Education Series, 1995 Flight monopropellant systems Mariner 4 Landsat Viking HEAO Voyager Pioneer Venus Intelsat V IUS Magellan Launch date 1964 1972 1976 1977 1977 1978 1980 1982 1989 Altitude control 3 Axis 3 Axis 3 Axis 3 Axis 3 Axis Spin 3 Axis 3 Axis 3 Axis No. thrusters 1 3 4, 3 12 16, 4, 4 7 20 12 12, 4, 8 Initial thrust, lb 50 1.0 10,600 1.1 0.2, 5, 100 1.5 0.1, 0.6, 5 0.2, 5, 100 Pressurization Regulated Blowdown Blowdown Blowdown Blowdown Blowdown Blowdown Blowdown Blowdown Pressurant N 2 N 2 N 2 N 2 N 2 He N 2 N 2 He No. prop tanks 1 1 2 2 1 2 2 1,2, or 3 1 Initial pressure, psia 530 350 450 350 270 450 Blowdown ratio - 3.3 3.5 1.8 1.8 4 Repressurization - No No No No No Yes No Yes Propellant Control Bladder Diaphragm Deceleration Diaphragm Diaphragm 5 rpm spin Capillary Diaphragm Diaphragm Tank shape Spherical Spherical Spherical Spherical Spherical Conosphere Barrel Spherical Spherical Crossover - - - Yes - Yes Yes Yes No Dry mass, lb 26.7 56.2 78 135 Propellant mass 21.5 67 185 300 230 86.2 410 123/Tank 293.2 Features Slug starts Simplicity Throttlable 400,000 cycle pulsing Electrother mal thrusters Removable tanks Primary 23 24 25 30 16 27 28 26 29 Refrnce 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 7 of 12 Image adapted from: SPACECRAFT PROPULSION, by Ch. D. Brown AIAA Education Series, 1995 Spacecraft bipropellant systems Transtage RCS Viking Orbiter Shuttle RCS Galileo Intelsat VI Mars Global Surveyor First launch 1964 1975 1981 1989 1989 1996 No. thrusters 8 1 (ACS by cold gas) 44 13 8 13 Thrust, lb 25,45 300 25,870 2.25,90 5,110 1,134 Engine cooling Ablative Beryllium Radiation cooled and insulated Radiation Radiation Radiation Fuel 50/50 mix of hydrazine and UDMH MMH MMH MMH MMH Hydrazine Oxidizer Nitrogen tetroxide Nitrogen tetroxide Nitrogen tetroxide Nitrogen tetroxide Nitrogen tetroxide Nitrogen tetroxide Mixture ratio 1.60 1.50 1.6 1.6 Propellant control Teflon diaphragms Capillary vane devices Capillary screens Centrifugal 10(rpm) Centrifugal Capillary vane Propellant tanks Titanium equal volume spherical Titanium equal volume barrel Titanium equal volume, spherical Four equal volume, titanium, spherical Eight equal volume, titanium, spherical Three equal volume, titanium, barrel Pressurization Regulated nitrogen Regulated helium Regulated helium Regulated helium Regulated helium Vapor mixing prevention Single, soft seat check valves Series soft seat check valves Single soft seat check valves, low leak design Single check valves Pyro-valves Dry mass, lb 55 442 139 Propellants, lb 120 3137 2040 5100 to 5990 836 Primary reference 32 33 34 features Early design Beryllium cooling Large size, multiuse Spinner, flushing burns Spinner, redundant half-system Dual-mode operation 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 8 of 12 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 9 of 12 Additional Reading for System Design: Mayer, N. L. “AIAA 96-2869, Advanced X-ray Astrophysics Facility – Imaging (AXAF- I) Propulsion Subsystem.” 32 nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference. Redondo Beach, CA: TRW Space & Electronics Group. July 1-3, 1996. pp. 1-10. 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 10 of 12 Some Examples of Small Solid Propellant Rockets for In-space Propulsion The STAR 13B incorporates the lightweight case developed for the STAR 13 with the propellant and nozzle design of the earlier TE-M-516 apogee motor. The motor case has been stretched 2.2 inches to provide for increased propellant loading. The motor has been used to adjust orbit inclination of a satellite from a Delta launch. MOTOR PERFORMANCE (70 ° F Vacuum) Burn Time/Action Time, sec 14.8/16.1 Ignition Delay Time, sec 0.02 Burn Time Average Chamber Pressure, psia 823 Action Time Average Chamber Pressure, psia 787 Maximum Chamber Pressure, psia 935 Total Impulse, lbf-sec 26,040 Propellant: Specific Impulse, lbf-sec/lbm 286.6 Effective Specific Impulse, lbf-sec/lbm 285.7 Burn Time Average Thrust, lbf 1708 Action Time Average Thrust, lbf 1577 Maximum Thrust, lbf 2160 SPIN CAPABILITY, rpm 120 WEIGHTS, lbm Total Loaded 103.7 Propellant 90.9 Case Assembly 5.64 Nozzle Assembly 3.72 Igniter Assembly 0.68 Internal Insulation 2.34 Liner 0.14 Miscellaneous 0.28 Total Inert (excluding igniter propellant) 12.80 Burnout 12.30 Propellant Mass Fraction 0.87 TEMPERATURE LIMITS Operation 40 to +110°F Storage 40 +110 CASE Material 6Al-4V Titanium Minimum Ultimate Strength, psi 165,000 Minimum Yield Strength, psi 152,000 Hydrostatic Test Pressure, psi 1330 Yield Pressure, psi 1394 Hydrostatic Test Pressure/Maximum Pressure 1.05 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 11 of 12 Nominal Thickness, In. 0.035 NOZZLE Exit Cone Material Vitreous Silica Phenolic Throat Insert Material ATJ Graphite Initial Throat Area, in 2 1.14 Exit Diameter, In. 8.02 Expansion Ratio, Initial/Average 49.8/41.0 Expansion Cone Half Angle, deg 17 Type Fixed Number of Nozzles 1 LINER Type TL-H-304 Density, lbm/ in. 3 0.045 IGNITION TRAIN Components S&A/ETA/TBI/pyrogen igniter Minimum Firing Current per Detonator, amperes 5.0 Circuit Resistance per Detonator, ohms 1.0 No. of Detonators and TBIs 2 Squib or TBI compatible PROPELLANT Propellant Designation and Formula TP-H-3082 AP-70% Al-16% CTPB Binder-14% PROPELLANT CONFIGURATION Type Internal burning, 8-point star Web, In. 4.187 Web Fraction, % 62 Silver Fraction, % 2 Propellant Volume, in. 3 1446 Volumetric Loading Density 92 Web Average Burning Surface Area, in. 2 345 Initial Surface to Throat Area Ratio 316 PROPELLANT CHARACTERISTICS Burn Rate at 1000 psia, in./sec 0.301 Burn rate Exponent 0.31 Density, lbm/in. 3 0.0628 Temperature Coefficient of Pressure, %/ ° F 0.10 Characteristic Exhaust Velocity, ft/sec 5025 Adiabatic Flame Temperature, ° F 5662 Effective Ratio of Specific Heats (chamber) 1.16 16.522, Space Propulsion Lecture 7 Prof. Manuel Martinez-Sanchez Page 12 of 12 (Nozzle Exit) 1.21 CURRENT STATUS Production BC1355B 4/91