LAUNCH SYSTEMS Col John Keesee 5 September 2003
LAUNCH SYSTEMS Col. John Keesee 5 September 2003
Outline Launch systems characteristics Launch systems selection process Spacecraft design envelope environments
Outline • Launch systems characteristics • Launch systems selection process • Spacecraft design envelope & environments
Lesson obiectives 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
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 basics fuel in e Thrust Oxidizer in A Throat Thrust eret Aelpe-p) F=ny Specific impulse SD≡ F mg Isp=K where k depends on y and the engine pressure ratio
Rocket Basics Thrust Specific impulse where K depends on J and the engine pressure ratio ( ) f p ep eA eVe F m M cT Isp K mg Isp F { me Ve Pe Ae fp Fuel in Oxidizer in Thrust pc Throat
Rocket equation F-m isp aFM M,=M.-mt ve ve ve t dmd △=a=p8-dt △V= g Isp nM。M g Ispenyo=g Ispin R propellant Where R- is the mass ratio Assumes zero losses due to drag and gravity
Rocket Equation Where is the mass ratio (Assumes zero losses due to drag and gravity) m t Mo veh g M veh M m Isp veh M a F ' V adt Isp g ³ d m dt dt Mo d m d t t t o t f ³ ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¸ ¸ ¸ ¸ ¸ ¹ · ¨ ¨ ¨ ¨ ¨ ¨ ¨ © § ¸ ¸ ¸ ¸ ¸ ¸ ¸ ¹ · ¨ ¨ ¨ ¨ ¨ ¨ ¨ © § ' g Isp n R f M g Isp n Mo propellant Mo M V g Isp " n Mo " " R Mo Mf
Rocket Equation( Cont) M-Mielsp g-1=M △/spg Mn=mass of propellant M =initial mass M =final mass Av vehicle velocity change vehicle mass
Rocket Equation (Cont.) Mp Mf e ' V Isp g § © ¨¨¨¨¨¨¨¨¨ ·¹¸¸¸¸¸¸¸¸¸ 1 ª ¬ « « « « « « « º ¼ » » » » » » » Mo 1 e ' V/Isp g § © ¨¨¨¨¨¨ ·¹¸¸¸¸¸¸ ª ¬ « « « « « º ¼ » » » » » M p = mass of propellant M o = initial mass M f = final mass 'V = vehicle velocity change Mveh = vehicle mass
Staging Near burnout. rocket acceleration is diminished because payload mass includes entire launch systems structure Staging removes lower stage structural weight △V;=g1pnx2 Mi =initial mass of rocket including all upper stages and payload Mi=final mass after stage has burned before separation i= stage number △V=∑AV
Staging • Near burnout, rocket acceleration is diminished because payload mass includes entire launch systems structure. • Staging removes lower stage structural weight Moi = 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 "n Moi Mf i § © ¨ ¨ ¨¨ · ¹ ¸ ¸ ¸¸