Difference between revisions of "Propulsion"
(Created page with " Category:Propulsion Theory Propulsion equation. This is the equation that links the electrical power, the propulsive force and the ISP. Pe = F x ISP *9,81 / 2n or Pe =...") |
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| + | [[Category:Propulsion]] | ||
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| + | ==Theory== | ||
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| + | ===Propulsion equation=== | ||
| + | This is the equation that links the electrical power, the propulsive force and the ISP. | ||
| + | |||
| + | P = F x ISP *9,81 / 2n or P= F x Ev /2n | ||
| − | + | where: | |
| + | |||
| + | P = power (Watts) | ||
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F = Engine force (Newtons) | F = Engine force (Newtons) | ||
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ISP = Specific impulse (Seconds) | ISP = Specific impulse (Seconds) | ||
| − | n = efficiency of | + | |
| + | n = efficiency of engine, for an [[ion thruster]] this is between 0,2 and 0,8, for a [[Propellant|chemical rocket]], or [[Nuclear thermal propulsion|nuclear thermal rocket]], essentially 1. | ||
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9,81 conversion factor | 9,81 conversion factor | ||
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Ev = Exhaust velocity (m/s) | Ev = Exhaust velocity (m/s) | ||
| − | Specific impulse | + | |
| + | ===Specific impulse=== | ||
ISP = Ev / 9,81 | ISP = Ev / 9,81 | ||
| + | |||
ISP = Specific impulse (Seconds) | ISP = Specific impulse (Seconds) | ||
| + | |||
Ev = Exhaust velocity (m/s) | Ev = Exhaust velocity (m/s) | ||
| − | Fuel consumption | + | |
| + | ===Fuel consumption=== | ||
m = F/Ev | m = F/Ev | ||
| + | |||
m = Fuel consumption (kg/s) | m = Fuel consumption (kg/s) | ||
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F = Force (Newtons) | F = Force (Newtons) | ||
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Ev = Exhaust velocity (m/s) | Ev = Exhaust velocity (m/s) | ||
| − | Velocity | + | |
| − | V = Ev x ln( | + | ===Velocity (Rocket equation)=== |
| + | V = Ev x ln(M<sub>o</sub>/M<sub>f</sub>) | ||
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Ev = Exhaust velocity (m/s) | Ev = Exhaust velocity (m/s) | ||
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V = ship final velocity (m/s) | V = ship final velocity (m/s) | ||
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ln = natural logarithm | ln = natural logarithm | ||
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| − | + | M<sub>o</sub> = Initial mass of the ship (kg) | |
| − | + | ||
| − | + | M<sub>f</sub> = Final mass of the ship (kg) | |
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The propulsive force is the force the engines produce to push the ship. This is factor of the available electrical energy, the engine efficiency and the propulsive system ISP and ejection velocity. | The propulsive force is the force the engines produce to push the ship. This is factor of the available electrical energy, the engine efficiency and the propulsive system ISP and ejection velocity. | ||
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Revision as of 10:39, 9 August 2019
Contents
Theory
Propulsion equation
This is the equation that links the electrical power, the propulsive force and the ISP.
P = F x ISP *9,81 / 2n or P= F x Ev /2n
where:
P = power (Watts)
F = Engine force (Newtons)
ISP = Specific impulse (Seconds)
n = efficiency of engine, for an ion thruster this is between 0,2 and 0,8, for a chemical rocket, or nuclear thermal rocket, essentially 1.
9,81 conversion factor
Ev = Exhaust velocity (m/s)
Specific impulse
ISP = Ev / 9,81
ISP = Specific impulse (Seconds)
Ev = Exhaust velocity (m/s)
Fuel consumption
m = F/Ev
m = Fuel consumption (kg/s)
F = Force (Newtons)
Ev = Exhaust velocity (m/s)
Velocity (Rocket equation)
V = Ev x ln(Mo/Mf)
Ev = Exhaust velocity (m/s)
V = ship final velocity (m/s)
ln = natural logarithm
Mo = Initial mass of the ship (kg)
Mf = Final mass of the ship (kg)
The propulsive force is the force the engines produce to push the ship. This is factor of the available electrical energy, the engine efficiency and the propulsive system ISP and ejection velocity.
