ASEN 1400 / ASTR 2500
Class #23
Colorado Space Grant Consortium
T-18

Announcements
- Guest Lecture – Spacecraft Propulsion
Launch is in 18 days

Brady’s Talk…
- What did you think?
HW #8…
- Everyone turn it in?
Movie Night Tonight…
- Show of hands as to who is coming
3

Colorado Space Grant Consortium

Colorado Space Grant Consortium

Bring all hardware
- Be prepared to give a 60 second into
- Be prepared to activate at beginning of class
- Be prepared to give a 60 second wrap up at end
6

Colorado Space Grant Consortium

http://my.execpc.com/~culp/space/as07_lau.jpg
An Introduction to
Stephen Hevert
Affiliate Professor
Metropolitan State College of Denver

What Is Propulsion?
• Initiating or changing the motion of a body
• Translational (linear, moving faster or slower)
• Rotational (turning about an axis)
• Space propulsion
• Rocket launches
• Controlling satellite motion
• Maneuvering spacecraft
• Jet propulsion
• Using the momentum of ejected mass
(propellant) to create a reaction force , inducing motion
At one time it was believed that rockets could not work in a vacuum -- they needed air to push against!!

Jet Propulsion Classifications
• Air-Breathing Systems
• Also called duct propulsion .
• Vehicle carries own fuel; surrounding air (an oxidizer ) is used for combustion and thrust generation
• Gas turbine engines on aircraft…
…or go karts!
• Rocket Propulsion
• Vehicle carries own fuel and oxidizer, or other expelled propellant to generate thrust:
• Can operate outside of the
Earth’s atmosphere
• Launch vehicles, upper stages, Earth orbiting satellites and interplanetary spacecraft … or
… a rocket powered scooter!
www.gadgets-reviews.com www.the-rocketman.com

Space Propulsion Classifications
Systems that use an expellant (e.g. on-board propellant)
Stored Gas or Vapor o Compressed gas o Ammonia o Butane o Nitrous Oxide
Chemical o Liquid o Solid o Hybrid
Electric o Electrothermal o Electrostatic o Electromagnetic
Solar o Solar thermal o Solar electric
Beamed Energy o Laser thermal o Microwave thermal o Microwave electric
Nuclear o Nuclear thermal o Nuclear electric o Antimatter
We’ll look at some of these today…
Systems that do not carry an expellant (extract energy/force from external source)
Sails o Solar sails (light or solar wind) o M2P2 (charged particles)
Beamed Energy o Laser reflector (light sail) o Microwave (Starwisp)
Interstellar Ramjet o Bussard drive
Tethers o Stationary o Rotating o Electrodynamic o Pumped
Aero/Gravity Assist o Aero assist o Aero braking o Aero capture o Gravity assist
Breakthrough Propulsion Physics o Space drives (warp drives) o Wormholes o Antigravity

Space Propulsion Applications
Terrestrial/Atmosphere/
Suborbital
Tactical Missiles
Sounding Rockets
Ballistic Missiles
Earth to Orbit
Launch Vehicles www.army-technology.com
blog.wired.com
In-Space
Realm of Existing
Technology
Orbit Transfer
Earth Orbiting
Upper Stages
& Satellites
Lunar Missions
Interplanetary Missions
Space
Exploration
The Future
Interstellar Space
Exploration
Star Trek!!
www.psrd.hawaii.edu

Space Propulsion Functions
• Primary propulsion
• Launch and ascent
• Maneuvering
• Orbit transfer, station keeping, trajectory correction
• Auxiliary propulsion
• Attitude control
• Reaction control
• Momentum management www.ksc.nasa.gov www.nasm.si.edu

A Brief History of Rocketry
• China (1232 AD)
• Earliest recorded use of rockets
• Black powder
• Russia (early 1900’s)
• Konstantin Tsiolkovsky
• Orbital mechanics, rocket equation
• United States (1920’s)
• Robert Goddard
• First liquid fueled rocket (1926)
• Germany (1940’s)
• Wernher von Braun
• V-2
• Hermann Oberth
• Russia (USSR)
• Phenomenal contributions…
• Korolev, Glushko, Keldysh onenew.wordpress.com
Wan-Hu tried to launch himself to the moon by attaching 47 black powder rockets to a large wicker chair ! (…Chinese folk tale)
Dr. Goddard goddard.littleto
npublicschools
.net
Prof. Tsiolkovsky www.geocities.com www.britannica.com Dr. von Braun

Stored Gas Propulsion
Fill
Valve
Low Pressure
Isolation
Valve
Gas
Propellant
Tank
P
Pressure
Gage
Filter
High Pressure
Isolation
Valve
Pressure
Regulator
Thruster
• Primary or auxiliary propulsion
• High pressure gas ( propellant ) is fed to low pressure nozzles through pressure regulator
• Release of gas through nozzles ( thrusters ) generates thrust
• Currently used for momentum management of the Spitzer
Space telescope
• Propellants include nitrogen, helium
• Very simple in concept

Chemical Propulsion Classifications en.wikivisual.com www.aerospaceweb.org
• Liquid Propellant
• Pump Fed
• Launch vehicles, large upper stages
• Pressure Fed
• Smaller upper stages, spacecraft
• Monopropellant
• Fuel only
• Bipropellant
• Fuel & oxidizer
• Solid Propellant
• Launch vehicles, Space
Shuttle, spacecraft
• Fuel/ox in solid binder
• Hybrid
• Solid fuel/liquid ox
• Sounding rockets, X Prize news.bbc.co.uk

Monopropellant Systems
Nitrogen or helium
Hydrazine
Fuel Fill Valve
Isolation Valve
P
Filter
Propellant
Tank
Pressure
Gage
• Hydrazine fuel is most common monopropellant.
• N
2
H
4
• Decomposed in thruster using iridium catalyst to produce hot gas for thrust.
• Older systems used hydrogen peroxide (H
2
O
2
) before the advent of hydrazine catalysts.
• Typically operate in blowdown mode (pressurant and fuel in common tank).
Thrusters
Thrusts of 1 to 400 N (0.2 to
100 lb f
) are common.

Monopropellant Systems
5 lbf thrusters used on the Compton
Space Telescope (Gamma Ray
Observatory)
Northrop Grumman
1 lbf thrusters manufactured by
Northrop Grumman www.aerojet.com

Bipropellant Systems
FUEL
Engine
P P
OX
Isolation
Valves
Thrust Chamber
Nozzle
• A fuel and an oxidizer are fed to the engine through an injector and combust in the thrust chamber of the engine
• Combustion products accelerate in a convergingdiverging nozzle
• Hypergolic : no igniter needed -propellants react on contact in thrust chamber
• Cryogenic propellants include
LOX (-423 ºF) and LH2 (-297 ºF).
• Igniter required
• Storable propellants include kerosene (RP-1), hydrazine, nitrogen tetroxide (N
2
O
4
), monomethylhydrazine (MMH)

Bipropellant Thrusters
AMPAC-ISP
Bipropellant thrusters are used for orbit transfer and for attitude control, with thrusts ranging from 4 to 440 N (1 to 100 lb f
)
AMPAC-ISP
4 N
Astrium

Liquid Propellant Systems
• Pump fed systems
• Propellant delivered to engine using turbopump
• Gas turbine drives centrifugal or axial flow pumps
• Large, high thrust, long burn systems: launch vehicles, space shuttle
• Different cycles developed.
F-1 engine turbopump:
• 55,000 bhp turbine drive
• 15,471 gpm (RP-1)
• 24,811 gpm (LOX)
A 35’x15’x4.5’ (ave.
depth) backyard pool holds about 18,000 gallons of water.
How quickly could the F-1 turbopumps empty it ?
Ans: In ~27 seconds!
Photos history.nasa.gov
F-1 Engine Turbopump
H-1 Engine Turbopump

Rocket Engine Power Cycles
• Gas Generator Cycle
• Simplest
• Most common
• Small amount of fuel and oxidizer fed to gas generator
• Gas generator combustion products drive turbine
• Turbine powers fuel and oxidizer pumps
• Turbine exhaust can be vented through pipe/nozzle, or dumped into nozzle
• Saturn V F-1 www.aero.org/publications/ crosslink/winter2004/03_side bar3.html
www.answers.com

Rocket Engine Power Cycles - cont
• Expander
• Fuel is heated by nozzle and thrust chamber to increase energy content
• Sufficient energy provided to drive turbine
• Turbine exhaust is fed to injector and burned in thrust chamber
• Higher performance than gas generator cycle
• Pratt-Whitney RL-10 www.aero.org/publications/ crosslink/winter2004/03_sidebar3.
html science.nasa.gov

Rocket Engine Power Cycles - cont www.aero.org/publications/ crosslink/winter2004/03_side bar3.html
• Staged Combustion www.rocketrelics.com
• Fuel and oxidizer burned in preburners (fuel/ox rich)
• Combustion products drive turbine
• Turbine exhaust fed to injector at high pressure
• Used for high pressure engines
• Most complex, requires sophisticated turbomachinery
• Not very common, but
very high performance
• SSME (2700 psia) shuttle.msfc.nasa.gov

The Big Engines…
F-1 Engine
Saturn V
1.5 million lbs thrust (SL)
LOX/Kerosene www.flickr.com
Main Engine
Space Shuttle
374,000 lbs thrust (SL)
LOX/H
2 spaceflight.nasa.gov
RD-170
1.78 million lbs thrust (SL)
LOX/Kerosene www.aerospaceguide.net

Solid Propellant Motors
• Fuel and oxidizer are in solid binder.
• Single use -- no restart capability.
• Lower performance than liquid systems, but much simpler.
• Applications include launch vehicles, upper stages, and space vehicles.
www.aerospaceweb.org
www.propaneperformance.com www.nationalmuseum.af.mil

Hybrid Motors
Oxidizer Tank
Ox Control Valve
Solid
Propellant
Nozzle
• Combination liquid-solid propellant
• Solid fuel
• Liquid oxidizer
• Multi-start capability
• Terminate flow of oxidizer
• Fuels consist of rubber or plastic base, and are inert.
• Just about anything that burns…
• Oxidizers include LO
2
, hydrogen peroxide (H
2
O
2
) and nitrous oxide (NO
2
)
• Shut-down/restart capability.







Propulsion Calculations
• Thrust & Specific Impulse
• Thrust is the amount of force generated by the rocket.
• Specific impulse is a measure of performance
(analogous to miles per gallon)
• Units are seconds
I sp

F w
F

rocket thrust w

weight flowrate of propellant
• Rocket Equation

V
 gI sp ln m i m f g

9.8 m /s
2 m i

mass of vehicle before burn m m f p

mass of vehicle after burn

mass of propellant for

V
 m i
 m f m p
 m i


1
 e

V gI sp


Rocket equation assumes no losses (gravity effects, aerodynamic drag).
Actually very accurate for short burns in Earth orbit or in deep space!

Specific Impulse Comparison
• Stored gas
• Monopropellant hydrazine
• Solid rocket motors
• Hybrid rockets
• Storable bipropellants
• LOX/LH2 www.rocketrelics.com
• 60-179 sec
• 185-235 sec
• 280-300 sec
• 290-340 sec
• 300-330 sec
• 450 sec
Specific impulse depends on many factors: altitude, nozzle expansion ratio, mixture ratio
(bipropellants), combustion temperature, combustion pressure
This thruster was used on the
Viking Lander. It has a specific impulse of about 225 seconds.

Mission Delta-V Requirements
Mission (duration)
Earth surface to LEO
LEO to Earth Escape
LEO to Mars (0.7 yrs)
LEO to Neptune (29.9 yrs)
LEO to Neptune (5.0 yrs)
LEO to Alpha-Centauri (50 yrs)
ΔV (km/sec)
7.6
3.2
5.7
13.4
70
30,000
LEO = Low Earth orbit (approx. 274 km)
That’s actually very low….


Propellant Calculation Exercise
• Determine the mass of propellant to send a 2500 kg spacecraft from LEO to Mars (0.7 yr mission).
• Assume the 2500 kg includes the propellant on-board at the start of the burn.
• Assume our engine has a specific impulse of 310 sec
(typical of a small bipropellant engine).
• Use the rocket equation: m p
 
2500





1
 e
9 .

5700
 





2117 kg
Most of our spacecraft is propellant! Only 383 kg is left for structure, etc! How could we improve this?

Electric Propulsion
• Classifications
• Electrothermal
• Electrostatic
• Electromagnetic
• Characteristics
• Very low thrust
• Very high Isp
• > 1000 sec
•
Requires large amounts of power
(kilowatts)
This image of a xenon ion engine , photographed through a port of the vacuum chamber where it was being tested at NASA's Jet Propulsion Laboratory, shows the faint blue glow of charged atoms being emitted from the engine. The ion propulsion engine is the first non-chemical propulsion to be used as the primary means of propelling a spacecraft.

Electrothermal Propulsion rocket.itsc.uah.edu
• Electrical power is used to add energy to exhaust products
• Resistojet
• Catalytic decomposition of hydrazine is augmented with high power electric heater
• 800 – 5,000 W
• Arcjet
• High voltage arc at nozzle throat adds thermal energy to exhaust
• Various gaseous or vaporized propellants can be used.
www.fathom.com www.waynesthisandthat.com
www.nasa.gov

Electrostatic Propulsion www.plasma.inpe.br
• Electrostatic forces are used to accelerate charged particles to very high velocities
• Xenon Ion Thruster
• Xenon propellant
• Xenon is ionized by electron bombardment
• Thermionic cathode
• Positively charged particles accelerated by grid
• Electrons routed to second anode and injected into beam to neutralize aerospace.engin.umich.edu
ESA’s SMART-1 uses a xenon ion propulsion system (XIPS)

Electromagnetic Propulsion
• Electromagnetic forces are used to accelerate a plasma
• A gas consisting of positive ions, electrons
• 5000 – 9000 R
• Neutral beam is produced
• Higher thrust per unit area than electrostatic thruster
• Classifications
• Magnetoplasmadynamic
•
Pulsed plasma
• Electric discharge creates plasam from solid Telfon
• Hall effect
• Developed in Russia
• Flew on U.S. STEx mission (1998) www.nasa.gov

Interstellar Missions – The Future
• The challenges are formidable
• Immense distances…
• Alpha Centauri = 4.5 LY (closest interstellar neighbor)

1 LY = 9.46x10
12 km = 5.878x10
12 mi

Universe = ~156 billion LY across
• Immense size & mass & energy & speeds required…
• Propulsion systems with dimensions of 1000’s km
• Power levels 1000’s x greater than Human Civilization now produces ( > 14 TW est.)
• Speeds ~ .4c - .6c (c = speed of light)
• Trip times… Robotic Rendezvous goals
• 4.5 LY in < 10 years
• 40 LY in < 100 years (radius of nearest 1000 stars)
• Relativistic effects…
• Because of time dilation and mass increase; length contraction
• On telecommunications
• From collisions with interstellar matter

Consider the Voyager I Spacecraft… spacetoday.org
• 29 years after launch in 1977:
• It had travelled ~100 AU
• Far beyond Pluto
• ~150 million km
• 13.9 light-hours from sun
• Moving at 17.4 km/s
• 0.006% of the speed of light
• One of the fastest man-made vehicles
• It would take another 74,000 years to reach Alpha
Centauri at this rate
• Advanced technologies and breakthroughs will be necessary to reach the stars…
Source: Frisbee, R., “Impact of Interstellar Vehicle Acceleration and
Cruise Velocity on Total Mission Mass and Trip Time,” AIAA 2006-
5224, July 2006

Future Propulsion Technologies
Interstellar Ramjet
• Bussard Drive (1960)
• Electromagnetic scoop gathers interstellar hydrogen for propellant
• EM “Scoop” is 1000’s of km in size!
daviddarling.info
Beamed Energy
• Laser Light Sails
• Driven by massive spacebased laser and spacebased optics bibliotecapleyades.net

Future Propulsion Technologies- cont
Matter-Antimatter
• Highest energy per unit mass of any reaction known in physics
• Energy released by annihilation of matter by antimatter counterpart
Other Space Drive Ideas…

Future Propulsion Technologies- cont
Breakthrough Physics
• Yes, NASA funds research on
• Wormholes
• Warp drives bibliotecapleyades.net
Wormhole: a
“shortcut” through the spacetime continuum daviddarling.info
When I began my career in the late
1970’s, we’d joke about electric propulsion being the “propulsion of the future…and always will be!” Today it is used on communications satellites and interplanetary spacecraft.
What does the future hold for interstellar propulsion? Now it is the
“propulsion of the future”... but will it always be?

References
• Theory and design
• Sutton, G. P. and Biblarz, O., Rocket Propulsion
Elements, 7th ed.
,Wiley, 1987
• A classic; covers most propulsion technologies
• Huzel, D.K, and Huang, D. H., Modern Engineering for
Design of Liquid Propellant Rocket Engines (revised
edition), Progress in Aeronautics and Astronautics, Vol.
147, American Institute for Aeronautics and
Astronautics, 1992
• Dieter Huzel was one of the German engineers who came to the U.S. after WW II.
• Humble, R. W., et. al., Space Propulsion Design and
Anaylsis (revised edition), McGraw-Hill, 1995
• Covers chemical (liquid, solid, hybrid), nuclear, electric, and advanced propulsion systems for deep space travel

References - cont
• Rocket engine history
• Macinnes, P., Rockets: Sulfur, Sputnik and Scramjets,
Allen & Unwin, 2003
• Clary, D. A., Rocket Man: Robert H. Goddard and the
Birth of the Space Age , Hyperion Special Markets, 2003
• Ordway, F. I. and Sharpe, M., The Rocket Team , Apogee
Books, 2003
• The story of Werner von Braun, the V-2 and the transition of the German engineers to the United
States following WW II
• Sutton, G. P., History of Liquid Propellant Rocket
Engines , American Institute for Aeronautics and
Astronautics, 2006
• New, over 800 pages of rocket engine history

When things go badly… http://www.youtube.com/watch?v=gDnkEOKR1BE