RCAIDE.Library.Methods.Mass_Properties.Weight_Buildups.Conventional.General_Aviation.FLOPS.compute_systems_weight

compute_systems_weight

compute_systems_weight(vehicle)

Calculate the systems weight for general aviation aircraft using FLOPS methodology.

Parameters:

vehicle (RCAIDE.Vehicle()) –

Vehicle data structure containing:

• networkslist

  List of propulsion networks

• wings[‘main_wing’]Component

  Main wing data structure containing:

  • sweeps.quarter_chordfloat

    Quarter chord sweep angle [deg]

  • areas.referencefloat

    Wing reference area [m^2]

  • spans.projectedfloat

    Wing projected span [m]

  • flap_ratiofloat

    Flap area to wing area ratio

• fuselageslist

  List of fuselage components containing:

  • lengths.totalfloat

    Fuselage length [m]

  • widthfloat

    Fuselage width [m]

  • heights.maximumfloat

    Maximum fuselage height [m]

• flight_envelopeComponent

  Flight envelope data containing:

  • design_mach_numberfloat

    Design cruise Mach number

  • ultimate_loadfloat

    Ultimate load factor

  • design_rangefloat

    Design range [nmi]

• passengersint

  Number of passengers

• design_dynamic_pressurefloat

  Design dynamic pressure [Pa]

• mass_properties.max_takeofffloat

  Maximum takeoff weight [kg]

Returns:

output –

Data structure containing:

• W_flight_controlfloat

  Flight control system weight [kg]

• W_hyd_pnufloat

  Hydraulics and pneumatics weight [kg]

• W_instrumentsfloat

  Instruments weight [kg]

• W_avionicsfloat

  Avionics weight [kg]

• W_apufloat

  APU weight [kg], currently set to 0

• W_anti_icefloat

  Anti-ice system weight [kg], currently set to 0

• W_electricalfloat

  Electrical system weight [kg]

• W_acfloat

  Air conditioning weight [kg], currently set to 0

• W_furnishfloat

  Furnishing weight [kg]

• W_systemsfloat

  Total systems weight [kg]

Return type:

Data()

Notes

Calculates weights for all aircraft systems using FLOPS methodology.

Major Assumptions

• Hydraulic system pressure is 3000 psf

• Single fuselage configuration

• Pressure ratio for cabin pressure (cruise to sea level) is 0.85. i.e. almostno cabin pressurization

• Passenger cabin length is 25% of fuselage length

Theory

Flight Controls: .. math:

W_{fc} = 0.404 * S_w^{0.317} * (W_{TO}/1000)^{0.602} * N_{ult}^{0.525} * q^{0.345}

Instruments: .. math:

W_{in} = 0.48 * A_f^{0.57} * M^{0.5} * (10 + 2.5N_{c} + N_{ew} + 1.5N_{ef})

Hydraulic and Pneumatics: .. math:

W_{hyd} = 0.57 * (A_f + 0.27 * S_w) * (1 + 0.03N_{ew} + 0.05N_{ef}) * (3000 / P)^{0.35} * M^{0.33}

Electrical: .. math:

W_{elec} = 92 * L_f^{0.4} * W_f^{0.14} * N_{fuse}^{0.27} * N_{eng}^{0.69} * (1 + 0.044N_{c} + 0.0015N_{pax})

Avionics: .. math:

W_{av} = 15.8 * D_{range}^{0.1} * N_{fc}^{0.7} * A_f^{0.43}

Furnishing: .. math:

W_{furn} = 127 * N_{fc} + 44 * N_{pax} + 2.6 * L_f * (W_f + D) * N_{fuse}

Air Conditioning: .. math:

W_{ac} = 3.2 * (A_f * D)^{0.6} + 9 * N_{pax}^{0.83} * M + 0.075 * W_{av}

Where:

• W_{fc} is flight controls weight [lb]

• S_w is wing area [ft^2]

• W_{TO} is takeoff weight [lb]

• N_{ult} is ultimate load factor

• q is dynamic pressure [psf]

• A_f is fuselage planform area [ft^2]

• M is design Mach number

• N_{c} is number of crew

• N_{ew} is number of wing-mounted engines

• N_{ef} is number of fuselage-mounted engines

• P is hydraulic system pressure [psf]

• L_f is fuselage length [ft]

• W_f is fuselage width [ft]

• N_{fuse} is number of fuselages

• N_{eng} is total number of engines

• N_{pax} is number of passengers

• D_{range} is design range [nmi]

• N_{fc} is number of flight crew

• D is fuselage depth/height [ft]

References

[1] NASA. (1979). The Flight Optimization System Weights Estimation Method.

NASA Technical Report.