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ESA Document - Emits - ESA

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3.3.5.5 ACS for TMI 1 st<br />

HMM<br />

Assessment Study<br />

Report: CDF-20(A)<br />

February 2004<br />

page 195 of 422<br />

In this configuration six control points shall be actives: P1, P2, P3, P4, P5 and P6, as shown in<br />

Figure 3-51.<br />

P6<br />

P5<br />

P4<br />

Configuration Total<br />

mass<br />

(tonnes)<br />

P3<br />

Figure 3-51: TMI 1 st configuration<br />

Total<br />

length<br />

(m)<br />

comp<br />

CoG<br />

(m)<br />

EV<br />

Airlock A 1<br />

P2<br />

Habitation Module<br />

Inertia total<br />

kg*m^2/1000<br />

MAV 10 46 10<br />

HAB 19 65 29<br />

ERC 0 15 29 22874<br />

TEI 15 160 44 63444<br />

MOI 0 100 44 84414<br />

TMI 3rd 15 249 59 172759<br />

TMI 2 nd 15 332 74 370650<br />

TMI 1 ST 15 332 89 679909<br />

Table 3-38: TMI 1 st dimensions<br />

The ACS functions shall be:<br />

• Attitude control while cruising to Mars<br />

• Atmospheric disturbance rejection<br />

• Manoeuvres: a little re-orientation to get the optimal attitude for firing the TMI 1 st stage<br />

can be assumed.<br />

The last function is the dimensioning one. A re-orientation of 20 degrees in 4 minutes can be<br />

envisaged as dimensioning manoeuvre. This would mean a constant acceleration phase covering<br />

10 degrees in 2 minutes and a constant deceleration phase.<br />

The acceleration needed is: 2*Dtheta/t^2 = 2*10*pi/120/120^2= 2.4e-5 rad/sec^2<br />

The maximum torque needed is 17 000 Nm, which can be easily realized by using the higher<br />

stages ACS.<br />

As a result, in principle there would be no need for an ACS in the TMI 1 st stage.<br />

To give the control authority when the stage is not assembled on the main vehicle, most likely<br />

some ACS shall be envisaged as well. However the dimensioning is TBD.<br />

P1

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