1. An Introduction to Rocket
MAE 4316: Propulsion
An Introduction to Rocket
Propulsion Systems

2. Types of launch vehicle propulsion systems
Lesson Topics
Some math
Thrust, Impulse, Isp
Types of launch vehicle propulsion systems
Design considerations
Launch Trajectories
The Big Picture

3. Launch Trajectory

4. Rocket Propulsion
MATH
Take notes…

5. Liquid Rocket Engines
A liquid rocket engine is a system that uses completely liquid propellants to produce thrust
Advantages
High Isp
Throttle-able
Stop and restart
Reusable
High density Isp (compared to gas storage)
Disadvantages
Low Thrust (compared to solids)
Complex
Cryogenic storage of propellants
Safety

6. Liquid rocket engines are used for
Launch vehicles
Bipropellant systems
Fuel
Oxidizer
Generates enough thrust
Relatively high storage density
High Isp allows reasonable propellant mass for ΔV required

7. Liquid Rocket Components

8. Solid Rocket Motors
A solid rocket motor is a system that uses solid propellants to produce thrust
Advantages
High thrust
Simple
Storability
High density Isp
Disadvantages
Low Isp (compared to liquids)
Complex throttling
Difficult to stop and restart
Safety

9. Solid Rocket Motors Solid rocket motors are used for Launch vehicles
High thrust (high F/W ratio)
High storage density
Ballistic Missiles
Propellant storability
Excellent aging
Quick response
storability
high F/W ratio)

10. Solid Rocket Motor Components

11. Hybrid Propulsion Systems
A hybrid propulsion system is one in which one propellant is stored in liquid (or gaseous) state while the other is stored in solid phase.
Solid Propellant / Liquid (or gas) Oxidizer
Most Common
Solid Oxidizer / Liquid Propellant
Less Common

12. Hybrid Advantages SAFETY: Literally no possibility of explosion
Controllable
Throttle
Stop / Re-start
Safe exhaust products
Higher Isp than solids
Higher density Isp than liquids
Lower complexity than liquids
Lower inert mass fraction than liquids

13. Hybrid Disadvantages More complex than solids Lower Isp than liquids
Lower density Isp than solids
Lower combustion efficiency than either liquids or solids
O/F variability
Poor propellant utilization
Higher inert mass fraction than solids

14. Hybrid Schematic

15. Nuclear Thermal Propulsion (NTP)
Nuclear Propulsion
Nuclear Thermal Propulsion (NTP)
System that utilizes a nuclear fission reactor
Energy released from controlled fission of material is transferred to a propellant gas
Fission
Absorption of neutrons in a fuel material
Excitation of nucleus causes fuel atoms to split
Two new nulcei on average (Fission Fragments)
High KE from release of nuclear binding energy
Usually radioactive
1 to 3 free neutrons
Necessary to keep reaction going
Critical if each fission events leads to another
Can be absorbed by reactor material or leak from reactor

16. Nuclear Propulsion ADVANTAGES
High Isp (2-10x that of chemical systems)
Low Specific Mass (kg/kW)
High Power Allows High Thrust
High F/W
Use of Any Propellant
Safety
Reduced Radiation for Some Missions

17. A Nuclear/Chemical Comparison
One gram of U-235 can release enough energy during fission to raise the temperature of 66 million gallons of water from 25oC to 100oC.
By contrast, to accomplish the same sort of feat by burning pure octane, it would require 1.65 million gallons of the fuel

18. Nuclear Propulsion DISADVANTAGES: Political Issues Social Issues
Low Technology Readiness Level (Maturity)
Radiation issues (Shielding)
High Inert Mass

19. Nuclear Propulsion Schematic
Propellant Tank: Similar to tanks discussed for liquid propulsion systems. Tank can also be used as a radiation shield.
Turbopump: Provides high pressure propellants to the heat exchange region of the propulsion system. Warm gas from regeneratively cooled nozzle drives the turbines.
Radiation Shield: Protects the payload from radiation from the reactor by absorbing or reflecting neutrons and gamma rays.

20. Design Considerations
Why does the Space Shuttle look the way it does?

21. Launch Trajectory

22. Launch Trajectory

23. The Big Picture
Ballistic missiles and launch vehicles need large amounts of ΔV
As inefficient as rockets are (low Isp), they are currently the only means by which high velocities (hypersonic) can be easily obtained