L4 - Space & Rocket Propulsion Flashcards
What is a space propulsion system for?
- Get spacecraft into space
- Move them around once they get there
- Change their attitude
How does a rocket work?
A rocket converts mass and energy into thrust.
- Energy is transferred to propellant
- The energised propellant is converted to high velocity exhaust
How can the thrust be increased?
- Increasing the mass flow rate
- Increasing the exhaust velocity
How is the total rocket operation time called?
The burn time.
What are the different types of space propulsion systems?
- Chemical (Solid, Liquid, Hybrid)
- Electric (Electrothermal, Electrostatic, Electromagnetic)
- Nuclear Fission
Describe the funtionning of a standard chemical thermodynamic rocket.
A chemical reaction gives heat, then waste products are accelerated through a nozzle. In most chemical rockets, a fuel and oxidiser combine in a combustion chamber to produce hear and by-products.
What is a cold-gas rocket?
It is the simplest form of thermodynamic rocket. The mechanical energy is the pressurised propellant.
- Very reliable
- Multiple restarts/pulsing possible
- Low Ve (~400m/s) and thrust (<1N)
Used only for attitude control on small spacecraft.
What is a solid rocket?
It is a rocket that typically contains a mixture of fuel, oxidizer and binder all in a sigle package called a motor. It is used for boosters and upper stages.
What are the different types of liquid rockets?
- Bipropellant
- Monopropellant
- Cryogenic
- Storable
- Hypergolic
What constitutes a Bipropellant rocket?
Two liquid propellants, fuel and oxidiser, react together to produce heat and echaust products.
Mainly used in launch vehicles.
What constitutes a Monopropellant rocket?
One propellant which decomposes when in contact with a catalyst.
- Usually operated in pulsed mode
- Low performance but simple
Mainly used for satellite attitude and orbit control.
What constitutes a Cryogenic rocket?
Liquid fuel/oxidiser that need refrigeration.
What constitutes a Storable rocket?
Liquid fuel/oxidiser that can be stored indefinitely.
What constitutes a Hypergolic rocket?
Liquid fuel/oxidiser that reacts spontaneously.
What are hybrid rockets?
Rockets that combine aspects of liquid and solid systems by using liquid oxidiser and a solid fuel.
