Rocket Types EGR 4347 Analysis and Design of Propulsion Systems
Dec 18, 2015
Rocket Performance – Mars Mission
Thrust – force 1 N ¼ lbf
Exhaust Speed – Measure of fuel efficiency Sample Burn Time – How long the rocket must fire to
accelerate a 25-ton payload from low earth orbit to escape velocity. The time is inversely related to the thrust.
Sample fuel ratio – fraction of the total spacecraft mass taken up by propellant. The amount of fuel is exponentially related to the exhaust speed.
Scientific American – March 2000
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110K 4.5 21 min 55
Nuclear Rockets
Tested in 1960s Hydrogen heated to
2,500 deg C
Reactors can generate electricity
Public opposition
Scientific American – March 2000
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9.0 27 min 32
ION
1950s Electrical fields
accelerate particles
Scientific American – March 2000
Fuel – cesium or xenon Cathode dumps
electrons into flow at exit Grids get in the way
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9 27 min 32
Ion 30 30 79 days 22
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9 27 min 32
Ion 30 30 79 days 22
Hall Effect 30 15 90 days 38
Magnetoplasmadynamic (MPD)
Scientific American – March 2000
Magnetic acceleration Magnetic field electrically generated
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9 27 min 32
Ion 30 30 79 days 22
Hall Effect 30 15 90 days 38
MPD 100 20 - 100 21-25 days
6.7 - 31
Pulsed Inductive Thruster (PIT)
Argon Fuel Radial Magnetic Field
200 times a second No electrodes
Scientific American – March 2000
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9 27 min 32
Ion 30 30 79 days 22
Hall Effect 30 15 90 days 38
MPD 100 20 - 100 21-25 days
6.7 - 31
PIT 20 50 110 days 14
VASIMR
Variable Specific Impulse Magnetoplasma Rocket
Radio waves heat fuel
Ionized propellant (Hydrogen)
Magnetic fields
Scientific American – March 2000
Rocket Performance
Type Thrust (N) Exhaust Speed (km/s)
Burn Time Fuel ratio (%)
Chemical 110,000 4.5 21 min 55
Nuclear 67,000 9 27 min 32
Ion 30 30 79 days 22
Hall Effect 30 15 90 days 38
MPD 100 20 - 100 21-25 days 6.7 - 31
PIT 20 50 110 days 14
VASIMR H 40 300 53 days 2.4
VASIMR L 1,200 10 2.1 days 46