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LAUNCH SYSTEMSCol. John Keesee5 September 2003Outline• Launch systems characteristics• Launch systems selection process• Spacecraft design envelope & environments.Lesson Objectives• Each student will• Understand launch system characteristics, sizing and trade-offs.• Estimate launch system sizes, staging requirements.• Be able to select appropriate launch system for a given mission from available systems.• Be able to estimate spacecraft requirements driven by launch vehicle induced environments.• Determine costs of launch systems.Rocket BasicsThrustSpecific impulse where K depends on J and the engine pressure ratio)(f pepeAeVemFMcTKIspgmFIsp {meVePeAefpFuel inOxidizer inThrustpcThroatRocket EquationWhere is the mass ratio(Assumes zero losses due to drag and gravity)tmoMvehMgvehMIspmvehMFa 'V adt Is p g³dmdtdtModmdtttotf³¸¸¹·¨¨©§¸¸¸¸¸¸¸¹·¨¨¨¨¨¨¨©§¸¸¸¸¸¸¸¹·¨¨¨¨¨¨¨©§  ' RnIspgfMoMnIspgpropellantMoMoMnIspgV """R MoMfRocket Equation (Cont.)Mp Mfe'VIsp g§ © ¨ ¨ ¨ ¨ ¨ ¨ ¨ ¨ ¨ · ¹ ¸ ¸ ¸ ¸ ¸ ¸ ¸ ¸ ¸ 1ª ¬ « « « « « « « º ¼ » » » » » » » Mo1e'V/Isp g§ © ¨ ¨ ¨ ¨ ¨ ¨ · ¹ ¸ ¸ ¸ ¸ ¸ ¸ ª ¬ « « « « « º ¼ » » » » » Mp= mass of propellantMo= initial massMf= final mass'V = vehicle velocity changeMveh= vehicle massStaging• Near burnout, rocket acceleration is diminished because payload mass includes entire launch systems structure.• Staging removes lower stage structural weightMoi= initial mass of rocket including all upper stages and payload.Mfi= final mass after stage has burned before separation.i = stage number'V = 'Vi'Vi g Isp "nMoiMfi§ © ¨ ¨ ¨ ¨ · ¹ ¸ ¸ ¸ ¸ Staging (Cont.)O = payload fraction =orMpayload i= mass of payload plus all upper stagesStructure fractionMsi= mass structure for stage iMpi= mass propellant for stage i MpayloadMoOi MpayloadmoiiO 3i 1nOiHsi MsiMoi MsiMpiMsi Mpayload iLaunch Vehicle ForcesWLDVxzcpTIDFlight path angleAngle of attackax gTWsinID§ © ¨ ¨ · ¹ ¸ ¸ DWcosD§ © ¨ · ¹ ¸ LWsinD§ © ¨ · ¹ ¸ ª ¬ « « « « º ¼ » » » » az g cosID§ © ¨ ¨ · ¹ ¸ ¸ DWsinDLWcosDª ¬ « « « « º ¼ » » » » Launch System Selection Process• Mission needs and objective • Mission requirements– Altitude– Inclination– Right ascension of ascending node (RAAN)– Payload dimensions• Launch system performance, availability, cost, reliability• Fairings• UpperstageExample Launch SystemsLaunchSystemUpperStageLEO(kg)GTO(kg)GEO(kg)Polar(kg)AtlasIIASCentaur2A8640 3606 1050 7300Delta II 7920/25PAM-D 5089 1840 910 3890PegasusXL460 345Shuttle -IUS24,4005900 2360Taurus Star 37 1400 450 1060Titan IV -Centaur 8620 454014,110Example Orbit Transfer VehiclesCharacteristics PAM-D IUS CentaurLength (m) 2.04 5.2 9.0Diameter (m) 1.25 2.9 4.3Mass (kg) 2180 14,865 18,800Thrust (N) 66,440 200,000 147,000Isp 292.6 292.9 442Structure mass 180 1255 2100Propellant mass 2000 9710 16,700Airborne support equipment mass1140 3350 4310Launch Sites Criteria• Minimum inclination• Launch azimuth• WeatherOrbitalmotionTo sunEarth rotationUS Launch Sites and Launch Systems• Western range (Vandenberg AFB):– LMMS Titan II, IV-B, Athena– Boeing Delta II, III, EELV– OSC Taurus, Minotaur, Pegasus• Equatorial launch site:– Boeing SeaLaunch• Alaska Spaceport– OSC MinotaurUS Launch Sites and Launch Systems (continued)• Eastern Range (Cape Canaveral Air Station, Kennedy Space Center):– STS– LMMS Titan IV; Atlas II, IIA, IIAS; EELV– Boeing Delta II, III, EELV– Orbital Pegasus XL, (Taurus, Minotaur)– Coleman/TRW/IAI Shavit• Wallops Island– Pegasus XL, MinotaurTypical Launch Vehicle Integration Tasks• Mission Orbit Planning– Effect of launch delays, launch window definition• Launch vehicle and spacecraft performance analyses– LV performance variations vs mission impacts• Defining, implementing mission unique requirements– Ground processing, ground testing– Launch vehicle interfaces - power, command, telemetry, etc.– Critical s/c commands: self-generated, booster provided, backup timers?• Flight safety systems - range destruct protocols: installation and test of range destruct packages• Developing multi-agency day-of-launch launch ops procedures– Example: Go/No-Go limitsLaunch Services - Scheduling• LMMS Atlas Commercial template– @ 36 months, select a 3 month window– @ 12 months, select a 30 day slot– @ 6 months, select a launch day• STS templates:– 36+ months for a Primary payload– 24 months minimum for secondary payloadsPayload Integration• Fairing size and shape• Maximum accelerations• Vibration frequencies and magnitudes• Acoustic frequencies and magnitudes• Temperature extremes• Air cleanliness• Orbital insertion accuracy• Interfaces to launch site and vehicleGround handling, ground and airbornetransportation, and launch environment may bemore severe than space operating environmentFairings• Protection from aerodynamic loading• Diameter and length constraint• Acoustic environment• Jettison AltitudeStructural & Electrical Interface• Physical support adaptors• Separation/deployment system• Kick motor/Spin tables• Electrical interface• Access– Physical– Electrical– Optical– Radio frequencyPayload Environments•Thermal– Pre-launch– Ascent fairing radiant– Aero-heating (Free molecular heating)• Electromagnetic• Contamination•Venting• Acceleration• Vibration• Acoustics•ShockAcceleration Load FactorsLift off MaxAirloadsStage 1 shutdownStage 2 shutdownVehicle Axial LateralAxial Lateral Axial LateralAxial LateralTitan 34D/IUS steadyDynamic+1.5+1.5 + 5.0+2.0+ 1.0 + 2.50 - +4.5+ 4.0+2.00 – +2.5+ 4.0 + 2.0Atlas II steadydynamic+1.3+1.5 +1.0+2.2+ 0.3+0.4+ 1.2+5.5+ 0.5 + 0.5+4.0+ 2.0 0.5Delta steadydynamic+2.41.0 2 to 3 +6.0Shuttle IUS steadyDynamic+3.2+3.5+2.5+3.4+1.1to 3.2+0.25 to –0.59+3.2 +0.59Vibration Environments• Caused by– Launch system propulsive dynamic acceleration – Unsteady aerodynamic effects– Acoustic pressure from engines– Amplified mechanical response of vehicle structure• Includes ground and airborne transportation• Yields structural stiffness requirement on payload and adaptor/interface.Shock LoadsCaused by pyrotechnic devices used to separate from launch.Staging, engine starts and


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MIT 16 851 - LAUNCH SYSTEMS

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