ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 236 of 422
The mass of the engine frame was achieved by comparison with the one used for the TMI
module.
3.4.2.3.3 TEI module
The TEI module consists of one stack equal to the MOI one. This stack is located inside the MOI
backbone structure and attached to it, by means of rings and a three-point connection.
For the separation system of the last stage of the MOI module from TEI module, two options
were analysed:
• Vertical guiding rail system of the backbone, to allow only the axial descent
movement of the backbone
• The same separation system as the one used for Ariane-5 fairing. It consists of a pyro
cord, which breaks a bolted joint around the fairing
Option 2 was selected because the mass penalty is smaller and it is a simpler system to install.
For this system, the backbone has to be divided into two half cylinders, which are attached by a
bolted joint.
The MOI backbone operates like a fairing to the TEI module. The interior part of the MOI
backbone should be almost entirely covered with acoustic absorption panels, to counter noise
levels of vibration in the structure at lift-off.
3.4.2.3.4 MOI connection to THM
The connection between the propulsion module and the habitation module is made through an
aluminium cone of 4 mm thickness and 2 m length.
3.4.2.4 Budgets
The structural mass budget is shown in Table 3-61:
Item Nr. Mass [kg] Margin [%] Mass with Margin [kg]
LOX Tank 1 819.82 10 901.80
LH2 Tank 1 1126.12 10 1238.74
Lower Skirt 1 707.57 10 778.32
Stack Ring 2 153.08 10 183.69
Backbone 1 2136.13 20 2563.36
Backbone Ring 2 162.95 10 179.24
Engine Frame 1 1500 0 1500
Skin 1 484.2 5 508.44
LOX Tank Debris
Shielding
1 78.48 10 86.33
LH2 Tank Debris
Shielding
1 319.35 10 351.29
TOTAL 8291.21
Table 3-61: TMI stack structural mass budget