1AE6450 Rocket PropulsionSeitzman Rocket Overview-1Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Rocket Propulsion OverviewAE6450 Rocket PropulsionSeitzman Rocket Overview-2Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Rocket DefinitionRocket ≡ Device that provides thrust to a vehicle by accelerating some matter (the propellant) and exhausting it from the rocket– Most significant difference between rocket and air-breathing engines is the rocket carries all its own propellant2AE6450 Rocket PropulsionSeitzman Rocket Overview-3Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Rocket: Performance Issues• Thrust– important when there are minimum allowable acceleration requirements, e.g., launch in gravity field• Impulse– measure of rocket performance – usually normalized by mass of propellant required (specific impulse, Isp)• Other issues– structural weight, size, complexity, reliability,…∫dt)t(FAE6450 Rocket PropulsionSeitzman Rocket Overview-4Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Rocket Propulsion ElementsPropellantEnergy SourceStorageFeed SystemStorageConversionAcceleratorgas, liquid, solidchemical, pressure, nuclear, radiation (solar)Thermodynamic (pressure nozzle), electromagnetic (static, dynamic fields) same in chemical rocketsto press., temp., electricity, radiationfor gases/liquids3AE6450 Rocket PropulsionSeitzman Rocket Overview-5Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Examples: Pressure Rocket• Cold Gas Thruster⇒Cold gas (N2, hydrazine,…)stored at high pressure with thrust provided by accel-eration through nozzle– Propellant=Energy source (storage pressure)– Feed system: piping from storage to nozzle– Accelerator: nozzle (thermal to kinetic energy)AE6450 Rocket PropulsionSeitzman Rocket Overview-6Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Examples: Chemical Rocket• Bipropellant: LH2-LOX (H2/O2) ⇒Combust pressurized H2and O2in combustion chamber, nozzle exhaust– Propellant=Energy source(chemical)– Storage: liquid (cryogenic)tanks– Feed system: liquid pumps and piping– Energy conversion: chemical to thermal energy (combustion)– Accelerator: nozzle SSME4AE6450 Rocket PropulsionSeitzman Rocket Overview-7Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Examples: Electrical Rocket• Ion Engine⇒Ionize neutral gas (Xe); ionsaccelerated by E field;ions recombined with e-– Propellant: neutral gas– Energy source: e.g., nuclear – Energy conversion: nuclear tothermal to electrical – Accelerator: high voltageelectrostatic field acrosselectrodesAE6450 Rocket PropulsionSeitzman Rocket Overview-8Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Applications• Space Propulsion– Launch: from “planetary” body to orbit– Orbit Insertion: from launch orbit to mission orbit– Maneuvering: maintain or change orbit or trajectory– Attitude Control: orientation of vehicle• Aircraft Propulsion– High thrust/acceleration (sustained or boosters)– High speed flight (> ramjet/scramjet capability)5AE6450 Rocket PropulsionSeitzman Rocket Overview-9Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets• Thrust produced by conversion of – chemical energy to thermal energy– thermal energy to kinetic energy• Common Applications– Usual choice for high thrust rockets, e.g, launch, orbit change, aircraft propulsion– Also used for maneuvering and attitude controlAE6450 Rocket PropulsionSeitzman Rocket Overview-10Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets – Types• Gas rockets– fuel/oxidizer stored as gases ⇒ large storage volumes• Liquid rockets– stored as liquids, more complex but high impulse• Solid rockets– propellant is solid, lower impulse but simpler•Hybridrockets– usually solid fuel+liquid/gas oxidizer• Motors vs. Engines– Motor = propellant stored inside comb. chamber–Engine= storage outside combustion chamber6AE6450 Rocket PropulsionSeitzman Rocket Overview-11Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets – Liquid System• Subsystems– storage– feed system– thrust chamber assembly (TCA)TCAStorageFeed System+ IGNITERfrom history.nasa.govadapted from grc.nasa.govAE6450 Rocket PropulsionSeitzman Rocket Overview-12Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets – Liquid Propellants• Monopropellants– exothermic decomposition• hydrogen peroxide H2O2• hydrazine N2H4• Bi-propellants– fuel/oxidizer combustion•H2/ O2• RP-1 (kerosene) / O2• MMH (CH3NH-NH2) / N2O4– hypergolic: self-igniting on contact7AE6450 Rocket PropulsionSeitzman Rocket Overview-13Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets - Solid• Nothing but TCA•Casing– coolingnot required, protected by propellant•Grain– geometry (surface area/shape) of solid propellant– no feed system to control propellant flow rate, grain design to “program” burning rate – can be very high•Nozzle– no coolant available, higher T material requiredgraincasingigniterthroat insertnozzleAE6450 Rocket PropulsionSeitzman Rocket Overview-14Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Chemical Rockets- Solid Propellants• Homogeneous– fuel/oxidizer mixed at near molecular level• Heterogeneous– separate “fuel”and “oxidizer”–usually oxid. particles insolid binder• AP/rubber• AP/rubber/AlCoarse ParticlesFine Particles 10 μmBinder8AE6450 Rocket PropulsionSeitzman Rocket Overview-15Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights reserved.Other Rockets: Applications• Pressure (cold gas)– attitude control + maneuvering: reduced thrust as pressure used up, rendevous• Electrical– Arcjet thrusters - maneuvering + attitude control– Ion engines - space propulsion• Advanced systems– Nuclear thermal: like chemical rockets with nuclear-based heat addition, high thrust– Solar thermal – Magnetoplasmadynamic and other electrodynamicdevices, high impulse– Combined Cycles: typically combine air-breathing with rocket cycles for single-stage to orbit (SSTO)AE6450 Rocket PropulsionSeitzman Rocket Overview-16Copyright © 2003,2006,2010 by Jerry M. Seitzman. All rights