Propulsion Systems Design • Rocket Engine Basics • Survey of the Technologies • Propellant Feed Systems • Propulsion Systems Design

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Propulsion Systems Design • Rocket engine basics • Survey of the technologies • Propellant feed systems • Propulsion systems design

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 2 ENAE 791 - Launch and Entry Vehicle Design Thermal Rocket Exhaust Velocity • Exhaust velocity is ! + γ −1. 2γ ℜT - % p ( γ 0 ! 0 ' e * Ve = -1 −' * 0 γ −1 M - & p ) 0 ! , 0 / where

M ≡ average molecular weight of exhaust Joules ℜ ≡ universal gas const.= 8314.3 mole°K γ ≡ ratio of specific heats ≈1.2

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 3 ENAE 791 - Launch and Entry Vehicle Design

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€ € Ideal Thermal Rocket Exhaust Velocity • Ideal exhaust velocity is ! 2γ ℜT V = 0 ! e γ −1 M • Tis corresponds to an ideally expanded nozzle • All thermal energy converted to kinetic energy of exhaust • Only a function of temperature and molecular weight!

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 4 ENAE 791 - Launch and Entry Vehicle Design

€ Thermal Rocket Performance • Trust is

! T = m˙ Ve + ( pe − pamb)Ae • Eﬀective exhaust velocity ! A " c % T m˙ c c V p p e $ I = ' ! = ⇒ = e + ( e − amb) $ sp ' m˙ # g0 & • Expansion ratio

1 1 * γ −1- γ −1# & γ # & γ At # γ +1& pe γ +1, pe / = % ( % ( ,1 −% ( / A $ 2 ' $ p ' γ −1, $ p ' / e 0 + 0 .

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 5 ENAE 791 - Launch and Entry Vehicle Design

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€ A Word About Specific Impulse • Defined as “thrust/propellant used” – English units: lbs thrust/(lbs prop/sec)=sec – Metric units: N thrust/(kg prop/sec)=m/sec • Two ways to regard discrepancy - – “lbs” is not mass in English units - should be slugs – Isp = “thrust/weight flow rate of propellant” • If the real intent of specific impulse is T I = and T = mV˙ then I = V !!! sp m˙ e sp e

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 6 ENAE 791 - Launch and Entry Vehicle Design Nozzle Design

• Pressure ratio p0/pe=100 (1470 psi-->14.7 psi) Ae/At=11.9

• Pressure ratio p0/pe=1000 (1470 psi-->1.47 psi) Ae/At=71.6

• Diﬀerence between sea level and ideal vacuum Ve ! γ −1 # & γ Ve pe ! = 1−% ( V $ p ' ! e,ideal 0

• Isp,vacuum=455 sec --> Isp,sl=333 sec U N I V E R S I T Y O F Rocket Propulsion MARYLAND 7 ENAE 791 - Launch and Entry Vehicle Design

€ Solid Rocket Motor

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 8 ENAE 791 - Launch and Entry Vehicle Design Solid Propellant Combustion Characteristics

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 9 ENAE 791 - Launch and Entry Vehicle Design Solid Grain Configurations

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 10 ENAE 791 - Launch and Entry Vehicle Design Short-Grain Solid Configurations

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 11 ENAE 791 - Launch and Entry Vehicle Design Gemini Retrograde Engine

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 12 ENAE 791 - Launch and Entry Vehicle Design Advanced Grain Configurations

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 13 ENAE 791 - Launch and Entry Vehicle Design Liquid Rocket Engine

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 14 ENAE 791 - Launch and Entry Vehicle Design Liquid Propellant Feed Systems

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 15 ENAE 791 - Launch and Entry Vehicle Design Space Shuttle OMS Engine

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 16 ENAE 791 - Launch and Entry Vehicle Design Turbopump Fed Liquid Rocket Engine

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 17 ENAE 791 - Launch and Entry Vehicle Design Sample Pump-fed Engine Cycles

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 18 ENAE 791 - Launch and Entry Vehicle Design Gas Generator Engine Schematic

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 19 ENAE 791 - Launch and Entry Vehicle Design SpaceX Merlin 1d Engines

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 20 ENAE 791 - Launch and Entry Vehicle Design Falcon 9 Octoweb Engine Mount

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 21 ENAE 791 - Launch and Entry Vehicle Design Staged-Combustion Engine Schematic

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 22 ENAE 791 - Launch and Entry Vehicle Design RD-180 Engine(s) (Atlas V)

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 23 ENAE 791 - Launch and Entry Vehicle Design SSME Powerhead Configuration

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 24 ENAE 791 - Launch and Entry Vehicle Design SSME Engine Cycle

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 25 ENAE 791 - Launch and Entry Vehicle Design Liquid Rocket Engine Cutaway

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 26 ENAE 791 - Launch and Entry Vehicle Design H-1 Engine Injector Plate

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 27 ENAE 791 - Launch and Entry Vehicle Design Injector Concepts

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 28 ENAE 791 - Launch and Entry Vehicle Design TR-201 Engine (LM Descent/Delta)

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 29 ENAE 791 - Launch and Entry Vehicle Design Solid Rocket Nozzle (Heat-Sink)

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 30 ENAE 791 - Launch and Entry Vehicle Design Ablative Nozzle Schematic

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 31 ENAE 791 - Launch and Entry Vehicle Design Active Chamber Cooling Schematic

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 32 ENAE 791 - Launch and Entry Vehicle Design Boundary Layer Cooling Approaches

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 33 ENAE 791 - Launch and Entry Vehicle Design Hybrid Rocket Schematic

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 34 ENAE 791 - Launch and Entry Vehicle Design Hybrid Rocket Combustion

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 35 ENAE 791 - Launch and Entry Vehicle Design Thrust Vector Control Approaches

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 36 ENAE 791 - Launch and Entry Vehicle Design Gemini Entry Reaction Control System

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 37 ENAE 791 - Launch and Entry Vehicle Design Apollo Reaction Control System Thrusters

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 38 ENAE 791 - Launch and Entry Vehicle Design RCS Quad

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 39 ENAE 791 - Launch and Entry Vehicle Design Apollo CSM RCS Assembly

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 40 ENAE 791 - Launch and Entry Vehicle Design Lunar Module Reaction Control System

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 41 ENAE 791 - Launch and Entry Vehicle Design LM RCS Quad

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 42 ENAE 791 - Launch and Entry Vehicle Design Viking Aeroshell RCS Thruster

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 43 ENAE 791 - Launch and Entry Vehicle Design Viking RCS Thruster Schematic

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 44 ENAE 791 - Launch and Entry Vehicle Design Space Shuttle Primary RCS Engine

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 45 ENAE 791 - Launch and Entry Vehicle Design Monopropellant Engine Design

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986 U N I V E R S I T Y O F Rocket Propulsion MARYLAND 46 ENAE 791 - Launch and Entry Vehicle Design Cold-gas Propellant Performance

From G. P. Sutton, Rocket Propulsion Elements (5th ed.) John Wiley and Sons, 1986

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 47 ENAE 791 - Launch and Entry Vehicle Design Total Impulse

• Total impulse It is the total thrust-time product for the propulsion system, with units ! It = Tt =˙mvet ! ⇢V t = ! m˙

! It = ⇢V ve • To assess cold-gas systems, we can examine total impulse per unit volume of propellant storage I t = ⇢v V e U N I V E R S I T Y O F Rocket Propulsion MARYLAND 48 ENAE 791 - Launch and Entry Vehicle Design Performance of Cold-Gas Systems

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 49 ENAE 791 - Launch and Entry Vehicle Design Self-Pressurizing Propellants (CO2)

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 50 ENAE 791 - Launch and Entry Vehicle Design Self-Pressurizing Propellants (N2O)

Density! 625 kg/m3 Density! 1300 kg/m3

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 51 ENAE 791 - Launch and Entry Vehicle Design N2O Performance Augmentation • Nominal cold-gas exhaust velocity ~600 m/sec

• N2O dissociates in the presence of a heated catalyst engine temperature ~1300°C 2N O 2N + O 2 ! 2 2 exhaust velocity ~1800 m/sec • NOFB (Nitrous Oxide Fuel Blend) - store premixed N2O/hydrocarbon mixture exhaust velocity >3000 m/sec

U N I V E R S I T Y O F Rocket Propulsion MARYLAND 52 ENAE 791 - Launch and Entry Vehicle Design Pressurization System Analysis Adiabatic Expansion of Pressurizing Gas γ γ γ pg,0Vg = pg, f Vg + pl Vl Pg0, Vg Pgf, Vg Known quantities:

Pg,0=Initial gas pressure

P , V P , V L L L L Pg,f=Final gas pressure

PL=Operating pressure of propellant Initial Final tank(s)

VL=Volume of propellant tank(s)

Solve for gas volume Vg U N I V E R S I T Y O F ! Rocket Propulsion MARYLAND 53 ENAE 791 - Launch and Entry Vehicle Design

€ Boost Module Propellant Tanks • Gross mass 23,000 kg – Inert mass 2300 kg – Propellant mass 20,700 kg

– Mixture ratio N2O4/A50 = 1.8 (by mass)

• N2O4 tank – Mass = 13,310 kg – Density = 1450 kg/m3 3 – Volume = 9.177 m --> rsphere=1.299 m • Aerozine 50 tank – Mass = 7390 kg – Density = 900 kg/m3 3 – Volume = 8.214 m --> rsphere=1.252 m U N I V E R S I T Y O F Rocket Propulsion MARYLAND 54 ENAE 791 - Launch and Entry Vehicle Design Boost Module Main Propulsion 3 • Total propellant volume VL = 17.39 m • Assume engine pressure p0 = 250 psi • Tank pressure pL = 1.25*p0 = 312 psi • Final GHe pressure pg,f = 75 psi + pL = 388 psi • Initial GHe pressure pg,0 = 4500 psi • Conversion factor 1 psi = 6892 Pa • Ratio of speciﬁc heats for He = 1.67 1.67 ! 1.67 1.67 3 (4500 psi)Vg = (388 psi)Vg + (312 psi)(17.39 m ) 3 • Vg = 3.713 m p M ρ = g,0 • Ideal gas: T=300°K --> He ℜT0 3 ρ=49.7 kg/m (4500 psi = 31.04 MPa) MHe=185.1 kg U N I V E R S I T Y O F Rocket Propulsion MARYLAND 55 ENAE 791 - Launch and Entry Vehicle Design

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