Report

Rocket Engines • Liquid Propellant – Mono propellant • Catalysts – Bi-propellant • Solid Propellant – Grain Patterns • Hybrid • Nuclear • Electric Performance Energy Safety Simplicity Expanding Gases Thrust Termination Restart Rocket Propulsion Liquid Rocket Engine Oxidizer Propellants Fuel Combustion Chamber Throat Nozzle Newton’s Laws The force required to accelerate a body is proportional to the product of the mass of the body and the acceleration desired. F = ma F m= a F a= m Rocket Thrust • Thrust is produced by the expanding propellants. • There is thrust from the difference between the ambient pressure and that of the exhaust gases at the nozzle exit (Pressure Thrust) and from the momentum of the propellants (Momentum Thrust). Total Thrust = Momentum Thrust + Pressure Thrust Propellant Mass Flow times Velocity F= .W g Nozzle Area times pressure differential Ve + Ae ( Pe - Pa) Exhaust Plumes and Nozzles Pexhaust < Pambient Pexhaust = Pambient Pexhaust > Pambient Under Expanded Ideal Expansion Over Expanded Expansion Ratio • Ratio of the nozzle exit area divided by the area at the nozzle throat. x= Ae Throat At Exit Specific Impulse • A measure of the energy in the propellants and of the efficiency of the rocket engine design • Specific Impulse is the ratio of the Thrust (Force) produced divided by the weight rate flow of propellants Isp = F .W Mass Ratio of a Vehicle Mass Ratio is the ratio between the booster mass before the rocket engine burn divided by the booster mass after rocket engine burn. MR = mi mf The Mass Ratio for a multistage rocket is the product of the Mass Ratios of all the stages, i.e. MROver All = MR1 x MR2 x MR3 x …x MRn Thrust-to-Weight Ratio • Measure of booster or stage design and manufacturing technology. Thrust Y= Vehicle Weight = F W • The higher the thrust-to-weight ratio the faster the vehicle will accelerate • The initial acceleration of a vehicle in “g’s” equals a=(Y-1) Ideal Rocket Equation • The ideal velocity change ( DV ) for each stage of a rocket is a function of the mass ratio ( MR) of the stage and the specific impulse ( Isp ) of the rocket DVi = Isp x g x ln MR • Ideal means you do not consider gravity changes, drag, or rotating Earth