17.01.2014 Views

Space Propulsion - IAP/TU Wien

Space Propulsion - IAP/TU Wien

Space Propulsion - IAP/TU Wien

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

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

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!