Airbrakes Overview:

  • Aerodynamic surfaces deployed during flight that create additional drag to slow rocket down
  • Airbrakes allow for altitude control and are used to reach a specific apogee
  • Revisiting and making major improvements to project from two years ago - improving upon mechanical design and incorporating active controls

Usage:

  • The airbrakes will be flying on our test launch vehicle
    • The initial controller design for the main Zephyrus launch vehicle showed us that we would not have control authority (low air densities at high altitudes_
    • Does not reduce complexity of project
    • Allows for active controls implementation

Functional Requirements - Structural:

  • Airbrakes shall be at minimum weight while still achieving other design requirements
  • Airbrakes shall be fully flush with OD of flight vehicle
  • Airbrakes casing shall interface with the FRR
  • Airbrakes shall be able to fully or partially deploy during flight with minimal friction
  • Airbrakes shall create sufficient drag force to enable the vehicle to hit target apogee

Servo:

  • GoBilda 2000 Series Dual Mode Servo

    Max No Load Speed (7.4V)

    60 RPM (0.17sec/60°)

    Max Rotation (7.4V)

    300o

    Stall Torque (7.4V)

    25.2 kg-cm

Design Overview:

Airbrakes Full Assembly FEA:

  • Fixed at radial holes
  • Drag force on each leaf: 7.673 lbf (@ 15s on test launch)
  • Minimum Factor of Safety: 7

Rotational Plate

  • Servo shaft goes through center of plate
  • Rotates for leaf extension and retraction
  • Connected to leaves via 4 bolts through each slotted curve
  • 60° rotation -> 1.29” of travel length
  • Travel distance determined by: leaf size, rail length, carriage length
  • Material - acrylic
  • FEA
    • Fixed at shaft hole and end of slots
    • Force: 30.7 lbf distributed between the end of each slot
    • Minimum Factor of Safety: 7.6

Leaves:

  • Maximize surface area to maximize drag
  • Outer edge of leaf flush with OD of flight vehicle
  • Max travel distance: 1.29”
    • Constrained by linear guide rail and carriage
  • Material - Aluminum 6061 T6

Bulkhead:

  • Attaches to airbrakes case
  • Attaches shafts for servo mounting
  • Four radial beams for linear guide rails
  • Material - Aluminum 6061 T6
  • FEA
    • Fixed at radial holes
    • Max drag of airbrakes = 4 x 7.673lbf = 30.7lbf applied on the 4 beams
    • Minimum Factor of Safety: 13

*Note: we are neglecting the high FOS as the airbrakes system is not a major contributor to overall launch vehicle mass

Testing:

Load Testing:

  • Goal: Analyze servo performance and
    airbrakes leaf extension and retraction
    under increasing loads
  • Max predicted test launch drag
    forces: 30lbf
  • Initial testing with no load condition
  • Max weight across all 4 leaves with
    reliable servo actuation: 16lbs

Inconclusive results potentially due to
software or physical test setup

Airbrakes Case

Purpose: 


Page Contributors: Kareena, Yasmin





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