1,360
edits
Space Shuttle: Difference between revisions
Jump to navigation
Jump to search
→Auxiliary Power Unit and Hydraulics System
| Line 395: | Line 395: | ||
As of June 2015, the APU and hydraulic system is modeled with a fair amount of detail and operated from a dedicated menu. APUs need to be started as part of the pre-launch checklist - refer to Help/Aircraft Checklists for the detailed procedure. <b>If the hydraulic system is not available during ascent, this will result in loss of the vehicle after SRB separation as there is no control over the Shuttle if the SSMEs can not be gimbaled.</b> | As of June 2015, the APU and hydraulic system is modeled with a fair amount of detail and operated from a dedicated menu. APUs need to be started as part of the pre-launch checklist - refer to Help/Aircraft Checklists for the detailed procedure. <b>If the hydraulic system is not available during ascent, this will result in loss of the vehicle after SRB separation as there is no control over the Shuttle if the SSMEs can not be gimbaled.</b> | ||
=== Active Thermal Control System === | |||
In orbit, the Shuttle's systems use on average about 14 kW of power, which eventually ends up heating the interior of the pressure vessel. Active cooling systems carry the heat load away and radiate it into space. A water coolant loop system takes care of the avionics bays and the cabin and exchanges heat with a two loop freon coolant system which also cools systems elsewhere in the Shuttle. The freon is circulated through the radiator panels located on the inside of the payload bay doors and dumps a maximum of about 18.000 W of heat into space. | |||
If the payload bay doors are closed (such as during ascent or entry), the freon loop can be cooled by flash evaporators which utilize quickly evaporating water sprayed on the freon tubes as coolant. To provide the cooling performance of the radiator, this system uses about 66 lb of water per hour, i.e. can only be a temporary measure as the water storage aboard would be quickly depleted otherwise. | |||
The heat balance in space is also influenced by the orientation of the Shuttle relative to the Sun and Earth - sunward facing surfaces tend to heat up to 350 K whereas shaded surfaces may cool down to 150 K. To ensure ice-free thruster and other exhausts, electrical heating elements may therefore be needed. | |||
=== Main Propulsion System === | === Main Propulsion System === | ||