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Thursday, April 20, 2023

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📅 Daily Questions

🌜 Last night, after work, I

🙌 One thing I’m excited about right now is

🚀 One+ thing I plan to accomplish today is

• [ ]

👎 One thing I’m struggling with today is

📝 Ephemeral Notes

• How rocket engines work
  • Rocket engines expels gas to propel the rocket forward
  • The engine contains a combustion chamber and rocket nozzle (de Laval nozzle)
    • Converts hot subsonic high-pressure gas that was in the chamber to cooler supersonic lower-pressure gas in the exhaust
    • The higher the pressure and temperature inside the engine the better
    • $H = E + (P \times V)$
    • Where $H$ is enthalpy or the total energy in the system, $E$ is internal energy, $P$ is pressure and $V$ is volume
  • Cold gas thrusters are the simplest form of rocket engines
    • The gas is kept in a pressurized tank and it expels out from high pressure to low pressure
    • The tank is cold because when gases expand out from high pressure the temperature drops due to Joule-Thompson effect
    • To store the most energy, a cold gas thruster needs to store as much propellant at the highest possible pressure in the lightest possible tank which is the biggest challenge
    • Example usage are the maneuvering thrusters on Falcon 9 interstage and on NASA’s manned maneuvering units
  • Pressure fed engines
    • They can be monopropellant or bipropellant
    • The difference is that in addition to the pressure tank and exhaust valve, there is a propellant tank in between
    • This is more efficient because it utilizes the chemical energy from running the propellant over a chemical bed

Notes created today

List FROM "" WHERE file.cday = date("2023-04-20") SORT file.ctime asc

Notes last touched today

List FROM "" WHERE file.mday = date("2023-04-20") SORT file.mtime asc

created: 2023-01-16 11:50