Propulsion Flashcards
List three types of spacecraft
- Earth orbiters
- Planetary explorers
- Manned spacecraft
List types of spacecraft that are labelled as ‘Earth orbiters’
- comsats
- weather
- earth’s observers
- navigation
- astronomy / space physics
- military
List types of spacecraft that are labelled as ‘Planetary explores’
- fly-bys
- probes
- orbiters
- landers/rovers
List types of spacecraft that are labelled as ‘Manned’
- orbiters
- lunar landers
- stations
Give 3 main methods of producing propulsion in space
- Photon
- Rocket
- Solar sails
Give 4 types of rocket propulsion
- Thermal
- Cold gas
- Electric
- Nuclear
Give 2 types of thermal rocket propulsion
- Chemical
2. Solar
Give 3 types of chemical thermal rocket propulsion
- Solid
- Liquid
- Hybrid
Give 4 types of electrical rocket propulsion
- Electrothermal
- Electrostatic
- Lorentz
- Hall
Describe photon propulsion
- laser power beam can provide momentum directly to spacecraft
- heating air below aircraft cause it to expand and generate lift
- has to be a light aircraft
what is the spacecraft requirement to be able to use photon propulsion
needs to be light
Describe solar sails propulsion
- large sheets of thin film, one side of which is covered by reflective coating which reflects solar radiation
- the reflecting photons pass on their momentum to spacecraft
- only theoretical designs at present
What is the difference between aircraft Jet engine and liquid rocket engine
jet:
- uses oxygen in the atmosphere
- cannot be used in space
rocket
- oxidiser is carried by the rocket
- operates in and out of space
Give rocket equation
Vmax = Vr x ln( M / (M - Mb)) + Vo
What is the specific impulse
ratio of the thrust to the weight flow rate of propellant
Isp = Vr / g
Describe cold gas rocket propulsion
- just a controlled pressurised gas source and a nozzle
- simplest form of rocket propulsion
Describe solar thermal rocket propulsion
- solar energy can either be used directly or via solar cells that convert to electrical current
Describe chemical rocket propulsion
- most common for space applications
- propellant can be solid, liquid or hybrid
What are the advantages of using solid chemical rocket propulsion
- simplicity
- reliability
- launch time
What are the advantages of using liquid chemical rocket propulsion
- controllability
- throttling ability
- restart ability
What are the advantages of using hybrid chemical rocket propulsion
- safety
- controllability
- throttling ability
- restart
- environmentally cleaner
Describe electrothermal electrical propulsion
- resistojet is the simplest
- propellant is heated by passing over tungsten heating element
Describe electrostatic electrical propulsion
- take thrust from accelerating positive charged particles in a static electric field
- need to ensure stream of particles is neutralised so that charge doesn’t build up
Describe Halls/Lorentz electrical propulsion
Halls / Lorentz force are used instead of an electrostatic field
Describe nuclear propulsion
- solid phase reactor
- gaseous phase reactor
- nuclear charges
Why are multistage rockets used
to get rid of unnecessary weight and so increase speed of rocket for same amount of fuel
