Rockets Flashcards
Give 2 historical case studies in module
- German V-2
2. Soviet R7
Describe characteristics about German V-2 rocket
- first rocket to reach outside sensible atmosphere (80km)
- pumps were driven by steam turbine (steam produced by concentrated hydrogen peroxide with sodium permanganate catalyst)
- Very sharp tip which cause overheating because oblique shock wave
- first to use regenerative cooling
- used water in fuel (saved refinery cost and reduced combustion temp)
How was unstable combustion and destructive vibration overcome in German V-2 rocket
- clustered 18 smaller combustion chambers to fire into a single large chamber
- made rocket very heavy and difficult to cool
- used regenerative cooling technique
Describe engine config. of soviet R7
- 4 break-away liquid-fuelled engines surround a central core
- core acts like a ‘second stage’
- Pressure and Temp much higher than V2 rocket
What fuel did Soviet R7 rocket use
kerosene and liquid oxygen
- meant much higher temperatures!
How does regenerative cooling system work on Soviet R7 engine
- between thin inner wall and steel outer wall was corrugated steel sheets
- this helped structure and allowed for cooling fuel to flow past
- layers joined by brazing with silver solder
Give heat flux equation to calculate heat between inner and outer walls
Q = heat flux = k (Twg - Twl) / L
Why does Elon Musk use stainless steel for re-entry vehicle
- much stronger and not brittle at cryogenic temp
- much cheaper than carbon fibre
Why was R7 rocket so innovative
Had the capability to use variable mixture ratio between fuel and oxidiser
Describe Soyuz rocket
- direct descendant of R7 rocket
- world’s most used space launcher
- low cost
- highly reliable
- 20 times cheaper than space shuttle launch
General issue with rocket propellants
Propellants of toxic so launch sites are not ideal
Describe Titan rocket family
- USA
- Famous for manned mission
- phased out due to toxic propellant and high cost
- used aerozine 50
Describe Atlas rocket family
- USA but used russian RD180 engine
- uses oxygen rich staged cycle
How must RP-1 fuel be burned
Needs to be ORSC, not FRSC
Oxygen rich staged combustion
Describe Delta rocket family
- still flying
- used RS68 engine
- used gas generator cycle t lower cost
- modified from space shuttle RS25
- operates at lower pressure
- Russian regenerative cooling applied
Describe Falcon rocket family
- SpaceX Falcon
- brought about many innovations
- sub-cooling of propellants for densification
- cavitation reduction in the pump
- use small but many engines to reduce cost and increase stability
- partial re-use is a goal
What is cavitation in a pump
cavitation is the formation of bubbles or cavities in liquid, developed in areas of relatively low pressure around an impeller.
Describe Chinese Long March rockets
- hypergolic propellants used for long stability at ambient temp
- launch sites not idea in mainland
- used to send astronauts to space
Describe European rockets
- Ariane 5 - 2 solid stage, main liquid hydrogen and oxygen
How does size affect a rocket
- impacts capability, applicability and cost
How does launch site impact rocket
- impacts payload
- effects orbit inclination
- at the equator, planet spins faster, also reason why rockets launched west to east
Give 3 advantages of equatorial launch
- Rotational speed of earth is greatest
- The need for a ‘plane change’ to the 0 degree inclination of geostationary orbit is eliminated
- Allows for bigger payload
Give 2 advantages of ocean launch
- Reduced risk of launching over populated areas
2. Absence of range conflicts with other launch systems (near total absence of ship/air traffic)
List 5 concerns with human cargo:
- Need to accommodate for human needs
- Sufficient uncertainty
- Capability of recovering crew
- Higher redundancy requirement
- Lower combustion chamber pressure
What are the 4 components of LES - Launch escape system
1 - launch abort system
2 - crew module
3 - service module
4 - spacecraft adapter
What are the differences between space shuttle and Buran rocket
- space shuttle main engines are with the shuttle
- buran rocket did not have main engines so it is counted as ‘payload’
- therefore buran can have more payload but main engines are not recoverable
Describe Saturn rocket family
- used for all Apollo missions
- 2nd largest liquid engine
- largest nozzle (creates instability issues)
- Used F1 engine in first stage of rocket (this had +- 35 bar pressure fluctuations - very high!)
Describe N1 rocket
- rocket soviets used in space race
- used ORSC with all oxygen flowing through pre-burner
Describe Space X raptor engine
- full-flow staged combustion
- eliminates the fuel-oxidiser turbine interseal
- lower pressure required in pumps
- can increase combustion chamber pressure
List 5 advantages of using liquified methane
- Better specific impulse
- Better cooling capabilities
- No/Less solid residue in pipe (compared to kerosene)
- No need for extra infrastructure and cheaper
- Can be produced on Mars from CO2 and Water
Pros and Cons of tap-off cycle
Pros
- Good for human space flight due to simplicity
- Less stressful engine shutdown process
Cons
- Startup more complicated
- Turbine has to withstand higher than normal temperatures
Pros and Cons of re-using rockets
Pros
1. Fuel cost only 0.3% of total cost so saves a lot on manufacturing
Cons
- Payload possible reduces by 30%
- Added cost of development, manufacturing, recovering, possible refurbishment
- Needs at least 10 re-uses to make it economically even
- Market for it might not be large enough
Pros and Cons of air launch to orbit
Pros
- Don’t have to fly through the low, dense atmosphere, the drag of which is high
- Nozzle can be optimised to lower ambient pressure
- Lower insurance cost and special propellants may be applied
- Launch from selected location
- Weather is less limiting factor
Cons
- Limited by aircraft size
- has to change from horizontal to vertical
- Saving may not be that great
Discuss space tourism
- Thus far 7 people have gone to space for a fee of 20-40 million dollars
- humans do have desire to go
- virgin galactic provide 6 mins weightless experience (hybrid rocket launched from aircraft)
Provide applications for rockets in supersonic car racing
- note jet engine alone is not enough
- can deliver good thrust-weight ratio
- bloodhound SSC
- has largest hybrid engine in europe using 3 engines
