Physics

EOS

Rocket Science

Eos, goddess of the dawn.

Page 1

Momentum

Derivation of the Rocket Equation

Thrust

 

Page 2

Speed of the Rocket During the Burn

 

Page 3

Rocket Acceleration

Position as a Function of Time

 

Page 4

Gravity

 

Page 5

Saturn V

Data

Stage 1 Calculation

 

Page 6

Saturn V

Stage 2, Stage 3 Calculations

 

Page 7

Saturn V Photo Gallery

 

Page 8

Saturn V Photo Gallery

 

Page 9

Equation Review

9 Equation Review

Equation Review

Variables

mr(t)                          mass of the rocket

vr(t)                           velocity of the rocket

vexhaust                        velocity of the exhaust gas, relative to the rocket

mgas(t)                       mass of the exhaust gas

p                                total momentum

R                                fuel burn rate

T                                thrust

m0fuel                         mass of full load of fuel

mbody                         mass of the rocket body – excluding fuel

mfinal                          rocket mass at the end of the burn

tfinal                            duration of the burn

a(t)                            rocket acceleration

x(t)                            rocket displacement

g                                acceleration due to gravity

 

The rocket equation in various forms

 

If there is no external force acting on the rocket, this is the form of the rocket equation ready to integrate

 

 

If there is an external force acting on the rocket, the expression for force goes on the left-hand side

For gravity as a constant force:

 

For gravity as a variable force:

 

 

Relation between the time-rate-of-change-of-mass of the rocket and the exhaust gas

 

Fuel burn rate

 

 

Thrust

 

 

 

Speed of the rocket – no gravity

 

Rocket speed at the end of the burn

 

 

 

Rocket speed at some time t during the burn

 

 

 

 

Speed of the rocket if gravity can be considered a constant force

 

Mass relationships

                 Rocket mass in terms of body mass and fuel mass

 

                 Initial mass of rocket – at ignition

 

If all of the fuel is burned, the mass of the rocket at the end of the burn is equal to the mass of the rocket body

 

Mass of the rocket as a function of time

 

Mass of the fuel as a function of time with a constant burn rate

 

Duration of the burn, if ignition occurs at t = 0

 

 

Acceleration – no gravity

At some time t

 

At ignition

 

 

At the end of the burn

 

 

Acceleration if gravity is considered a constant force

 

 

Displacement of the rocket during the burn – no gravity

 

 

 

                 Displacement of the rocket at the end of the burn

 

 

Displacement if gravity is considered a constant force

 

 

Force of gravity acting on the rocket

 

Expression for g, in general, at the surface of a planet

 

 

 

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