Structures Sybsystem Progress Report 9/15/95 - A&M

Structures Sybsystem Progress Report 9/15/95 - A&M

This week we worked primarily on generating a preliminary set of performance requirements for the structures subsystem. The initial requirements are listed below along with the assumptions made and their source. All questions were sent earlier in the week.

Our next task is determining some preliminary volume allocations for the various subsystems and generating several conceptual designs for the spacecraft structure.

Preliminary Requirements for Structures Subsystem

Provide structural support and withstand loads
  1. Engine Thrust Loads -
      Main Engine Maximum Thrust = 12,000 N
        Assume: Rocketdyne XLR-132 main engine
        Source: UT - Structures and Systems Integ. Final Design Review

      3 Auxillary Landing Engines = 500 N each
        Assume: 3 Marquardt R4-D engines
        Source: UT - Structures and Systems Integ. Final

  2. Acceleration Loads -
      7.7 g's axial (steady state)
      4.0 g's axial (dynamic)
      2.0 g's lateral (steady state)
      3.0 g's lateral (dynamic)
        Assume: Maximum mission loads occur during boost phase
        Source: "Space Mission Design and Analysis Guide to Space Launch Systems"

  3. Vibration and Acoustic Loads -
      Maximum Acoustic Load = 139.6 dB (1/3 octave)
      Minimum Lateral Frequency = 15 Hz
      Minimum Longitudinal Frequency = 35 Hz
      Maximum Flight Shock = 4100 g @ 1500 Hz (3 stage)
        Assume: 4010 payload bay in 7925 3-stage Delta-II launch platform Source: "Guide to Space Launch Systems"

  4. Thermal Loads -
      Operating Temerature Extremes: -160 deg C to +180 deg C
      Thermal stresses are a function of the material selected
        Source: Spacecraft Structures UT online reference document

  5. Internal Pressure -
      Assume: Propulsion (propellant tanks, engines, and associated plumbing) is the only pressurized system. All other subsystems and payloads are assumed to either operate in a vacuum or have a self-contained vacuum seal. The primary structure will therefore have to withstand essentially no internal pressures.

  6. Volume -
      Total Vehicle Volume => Delta-II payload volume
      Cylindrical and conical payload bay geometry:
      Cylindrical section: 100" diameter by 80" height
      Conical section: 100" base diameter by 114.3" height
        Source: Guide to Space Launch Systems

      Individual volume allocation of individual subsystems to be determined

  7. Environment -
      Radiation, magnetic, and micrometeroid protection requirements to be determined
        Assume: Oxygen and humidity control in launch vehicle payload bay provided by Delta-II


28 September 95
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