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MEC463 - Advanced Propulsion > Rockets > Flashcards

Rockets Flashcards

1
Q

Give 2 historical case studies in module

A
  1. German V-2

2. Soviet R7

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2
Q

Describe characteristics about German V-2 rocket

A
  • 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)
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3
Q

How was unstable combustion and destructive vibration overcome in German V-2 rocket

A
  • clustered 18 smaller combustion chambers to fire into a single large chamber
  • made rocket very heavy and difficult to cool
  • used regenerative cooling technique
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4
Q

Describe engine config. of soviet R7

A
  • 4 break-away liquid-fuelled engines surround a central core
  • core acts like a ‘second stage’
  • Pressure and Temp much higher than V2 rocket
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5
Q

What fuel did Soviet R7 rocket use

A

kerosene and liquid oxygen

  • meant much higher temperatures!
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6
Q

How does regenerative cooling system work on Soviet R7 engine

A
  • 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
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7
Q

Give heat flux equation to calculate heat between inner and outer walls

A

Q = heat flux = k (Twg - Twl) / L

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8
Q

Why does Elon Musk use stainless steel for re-entry vehicle

A
  • much stronger and not brittle at cryogenic temp

- much cheaper than carbon fibre

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9
Q

Why was R7 rocket so innovative

A

Had the capability to use variable mixture ratio between fuel and oxidiser

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10
Q

Describe Soyuz rocket

A
  • direct descendant of R7 rocket
  • world’s most used space launcher
  • low cost
  • highly reliable
  • 20 times cheaper than space shuttle launch
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11
Q

General issue with rocket propellants

A

Propellants of toxic so launch sites are not ideal

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12
Q

Describe Titan rocket family

A
  • USA
  • Famous for manned mission
  • phased out due to toxic propellant and high cost
  • used aerozine 50
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13
Q

Describe Atlas rocket family

A
  • USA but used russian RD180 engine

- uses oxygen rich staged cycle

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14
Q

How must RP-1 fuel be burned

A

Needs to be ORSC, not FRSC

Oxygen rich staged combustion

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15
Q

Describe Delta rocket family

A
  • 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
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16
Q

Describe Falcon rocket family

A
  • 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
17
Q

What is cavitation in a pump

A

cavitation is the formation of bubbles or cavities in liquid, developed in areas of relatively low pressure around an impeller.

18
Q

Describe Chinese Long March rockets

A
  • hypergolic propellants used for long stability at ambient temp
  • launch sites not idea in mainland
  • used to send astronauts to space
19
Q

Describe European rockets

A
  • Ariane 5 - 2 solid stage, main liquid hydrogen and oxygen
20
Q

How does size affect a rocket

A
  • impacts capability, applicability and cost
21
Q

How does launch site impact rocket

A
  • impacts payload
  • effects orbit inclination
  • at the equator, planet spins faster, also reason why rockets launched west to east
22
Q

Give 3 advantages of equatorial launch

A
  1. Rotational speed of earth is greatest
  2. The need for a ‘plane change’ to the 0 degree inclination of geostationary orbit is eliminated
  3. Allows for bigger payload
23
Q

Give 2 advantages of ocean launch

A
  1. Reduced risk of launching over populated areas

2. Absence of range conflicts with other launch systems (near total absence of ship/air traffic)

24
Q

List 5 concerns with human cargo:

A
  1. Need to accommodate for human needs
  2. Sufficient uncertainty
  3. Capability of recovering crew
  4. Higher redundancy requirement
  5. Lower combustion chamber pressure
25
Q

What are the 4 components of LES - Launch escape system

A

1 - launch abort system
2 - crew module
3 - service module
4 - spacecraft adapter

26
Q

What are the differences between space shuttle and Buran rocket

A
  • 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
27
Q

Describe Saturn rocket family

A
  • 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!)
28
Q

Describe N1 rocket

A
  • rocket soviets used in space race

- used ORSC with all oxygen flowing through pre-burner

29
Q

Describe Space X raptor engine

A
  • full-flow staged combustion
  • eliminates the fuel-oxidiser turbine interseal
  • lower pressure required in pumps
  • can increase combustion chamber pressure
30
Q

List 5 advantages of using liquified methane

A
  1. Better specific impulse
  2. Better cooling capabilities
  3. No/Less solid residue in pipe (compared to kerosene)
  4. No need for extra infrastructure and cheaper
  5. Can be produced on Mars from CO2 and Water
31
Q

Pros and Cons of tap-off cycle

A

Pros

  1. Good for human space flight due to simplicity
  2. Less stressful engine shutdown process

Cons

  1. Startup more complicated
  2. Turbine has to withstand higher than normal temperatures
32
Q

Pros and Cons of re-using rockets

A

Pros
1. Fuel cost only 0.3% of total cost so saves a lot on manufacturing

Cons

  1. Payload possible reduces by 30%
  2. Added cost of development, manufacturing, recovering, possible refurbishment
  3. Needs at least 10 re-uses to make it economically even
  4. Market for it might not be large enough
33
Q

Pros and Cons of air launch to orbit

A

Pros

  1. Don’t have to fly through the low, dense atmosphere, the drag of which is high
  2. Nozzle can be optimised to lower ambient pressure
  3. Lower insurance cost and special propellants may be applied
  4. Launch from selected location
  5. Weather is less limiting factor

Cons

  1. Limited by aircraft size
  2. has to change from horizontal to vertical
  3. Saving may not be that great
34
Q

Discuss space tourism

A
  • 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)
35
Q

Provide applications for rockets in supersonic car racing

A
  • note jet engine alone is not enough
  • can deliver good thrust-weight ratio
  • bloodhound SSC
  • has largest hybrid engine in europe using 3 engines

MEC463 - Advanced Propulsion (10 decks)

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