Space Propulsion - IAP/TU Wien
Space Propulsion - IAP/TU Wien
Space Propulsion - IAP/TU Wien
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limit cycle cont‘d<br />
<strong>Space</strong> <strong>Propulsion</strong><br />
pulsing properties of attitude – control thrusters<br />
Cold-gas -Helium<br />
500<br />
CoId-gas-Nitrogen 50<br />
5 - 10<br />
N 2<br />
H 4<br />
Monopropellant -<br />
500<br />
50 - 100 1200<br />
Bipropellant -<br />
N 2<br />
O 4<br />
/MMH<br />
Min thrust<br />
[mN]<br />
50<br />
10000<br />
Min impulse bit<br />
[mN.s]<br />
5 - 10<br />
750 - 1500<br />
Pulsing<br />
I sp<br />
[m/s]<br />
800<br />
1200<br />
nFL<br />
ω = t<br />
I<br />
v<br />
b<br />
t<br />
c<br />
I<br />
vΘ<br />
= 4<br />
nFLP<br />
L<br />
w<br />
coast time through 2Θ L<br />
4I<br />
Θ<br />
v L<br />
tcy<br />
= tc<br />
+ 2PW<br />
= + 2<br />
nLI<br />
min<br />
P<br />
w<br />
length of a cycle (from +Θ L to -Θ L ) if minimum impulse bits<br />
are used; usually, P W can be neglected<br />
nFP<br />
mp, cyc<br />
= 2<br />
I<br />
sp<br />
w<br />
•<br />
m p<br />
=<br />
2 2<br />
mp, cyc n IminL<br />
~<br />
propellant consumption per unit time<br />
t 2I<br />
I Θ<br />
cy<br />
sp<br />
v<br />
L