S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...

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The Effective Exhaust Velocity (measured) is:
Typical values of
ve < vEmax is due to:
P
A
E E ∗
ve = vE
+ = C C
o
F
m
Emax
Thermal losses in the motor
v
v
e
=
F
o
m
[m/s]
: 0.85 – 0.95 for cold gas
0.60 – 0.80 for hot gas
Friction losses in nozzle (boundary losses due to separation of gas flow from nozzle wall)
Nozzle exit pressure PE > P∞ governed by nozzle expansion ratio (< 200)
Losses due to gas condensation and gas dissociation in nozzle