weights_jet_transport.py

class openconcept.weights.weights_jet_transport.JetTransportEmptyWeight(**kwargs)

Bases: Group

Estimate of a jet transport aircraft’s operating empty weight using a combination of weight estimation methods from Raymer, Roskam, and others. See the docstrings for individual weight components for more details on the models used.

Inputs:

• ac|num_passengers_max (float) – Maximum number of passengers (scalar, dimensionless)

• ac|num_flight_deck_crew (float) – Number of flight crew members (scalar, dimensionless)

• ac|num_cabin_crew (float) – Number of flight attendants (scalar, dimensionless)

• ac|cabin_pressure (float) – Cabin pressure (scalar, psi)

• ac|aero|Mach_max (float) – Maximum aircraft Mach number (scalar, dimensionless)

• ac|aero|Vstall_land (float) – Landing stall speed (scalar, knots)

• ac|geom|wing|S_ref (float) – Wing planform reference area (scalar, sq ft)

• ac|geom|wing|AR (float) – Wing aspect ratio (scalar, dimensionless)

• ac|geom|wing|c4sweep (float) – Wing sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|wing|taper (float) – Wing taper ratio (scalar, dimensionless)

• ac|geom|wing|toverc (float) – Wing root thickness-to-chord ratio (scalar, dimensionless)

• ac|geom|hstab|S_ref (float) – Horizontal stabilizer reference area (scalar, sq ft)

• ac|geom|hstab|AR (float) – Horizontal stabilizer aspect ratio (scalar, dimensionless)

• ac|geom|hstab|c4sweep (float) – Horizontal stabilizer sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|hstab|c4_to_wing_c4 (float) – Distance from the horizontal stabilizer’s quarter chord (of the MAC) to the wing’s quarter chord (scalar, ft)

• ac|geom|vstab|S_ref (float) – Vertical stabilizer wing area (scalar, sq ft)

• ac|geom|vstab|AR (float) – Vertical stabilizer aspect ratio (scalar, dimensionless)

• ac|geom|vstab|c4sweep (float) – Vertical stabilizer sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|vstab|toverc (float) – Vertical stabilizer thickness-to-chord ratio (scalar, dimensionless)

• ac|geom|vstab|c4_to_wing_c4 (float) – Distance from the vertical stabilizer’s quarter chord (of the MAC) to the wing’s quarter chord (scalar, ft)

• ac|geom|fuselage|height (float) – Fuselage height (scalar, ft)

• ac|geom|fuselage|length (float) – Fuselage length, used to compute distance between quarter chord of wing and horizontal stabilizer (scalar, ft)

• ac|geom|fuselage|S_wet (float) – Fuselage wetted area (scalar, sq ft)

• ac|geom|maingear|length (float) – Length of the main landing gear (scalar, inch)

• ac|geom|maingear|num_wheels (float) – Total number of main landing gear wheels (scalar, dimensionless)

• ac|geom|maingear|num_shock_struts (float) – Total number of main landing gear shock struts (scalar, dimensionless)

• ac|geom|nosegear|length (float) – Length of the nose landing gear (scalar, inch)

• ac|geom|nosegear|num_wheels (float) – Total number of nose landing gear wheels (scalar, dimensionless)

• ac|propulsion|engine|rating (float) – Rated thrust of each engine (scalar, lbf)

• ac|propulsion|num_engines (float) – Number of engines (scalar, dimensionless)

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|weights|MLW (float) – Maximum landing weight (scalar, lb)

• ac|weights|W_fuel_max (float) – Maximum fuel weight (scalar, lb)

Outputs:

• OEW (float) – Total operating empty weight (scalar, lb)

• W_wing (float) – Estimated wing weight without structural fudge factor multiplier (scalar, lb)

• W_hstab (float) – Weight of the horizontal stabilizer without structural fudge factor multiplier (scalar, lb)

• W_vstab (float) – Weight of the vertical stabilizer without structural fudge factor multiplier (scalar, lb)

• W_fuselage (float) – Fuselage weight without structural fudge factor multiplier (scalar, lb)

• W_mlg (float) – Main landing gear weight without structural fudge factor multiplier (scalar, lb)

• W_nlg (float) – Nose landing gear weight without structural fudge factor multiplier (scalar, lb)

• W_nacelle (float) – Weight of the nacelles (scalar, lb)

• W_structure (float) – Total structural weight = fudge factor * (W_wing + W_hstab + W_vstab + W_fuselage + W_mlg + W_nlg + W_nacelle) (scalar, lb)

• W_engines (float) – Total dry engine weight (scalar, lb)

• W_thrust_rev (float) – Total thrust reverser weight (scalar, lb)

• W_eng_control (float) – Total engine control weight (scalar, lb)

• W_fuelsystem (float) – Total fuel system weight including tanks and plumbing (scalar, lb)

• W_eng_start (float) – Total engine starter weight (scalar, lb)

• W_furnishings (float) – Weight estimate of seats, galleys, lavatories, and other furnishings (scalar, lb)

• W_flight_controls (float) – Flight control system weight (scalar, lb)

• W_avionics (float) – Intrumentation, avionics, and electronics weight (scalar, lb)

• W_electrical (float) – Electrical system weight (scalar, lb)

• W_ac_pressurize_antiice (float) – Air conditioning, pressurization, and anti-icing system weight (scalar, lb)

• W_oxygen (float) – Oxygen system weight (scalar, lb)

• W_APU (float) – Auxiliary power unit weight (scalar, lb)

Options:

• structural_fudge (float) – Multiplier on the structural weight to allow the user to account for miscellaneous items and advanced materials. Structural weight includes wing, horizontal stabilizer, vertical stabilizer, fuselage, landing gear, and nacelle weights. By default 1.2 (scalar, dimensionless)

• total_fudge (float) – Multiplier on the final operating empty weight estimate. Structural components have both the structural fudge and total fudge factors applied. By default 1.15 (scalar, dimensionless)

• wing_weight_multiplier (float) – Multiplier on wing weight. This can be used as a very rough way of increasing wing weight due to lack of inertial load relief from the fuel. By default 1.0 (scalar, dimensionless)

• n_ult (float) – Ultimate load factor, 1.5 x limit load factor, by default 1.5 x 2.5 (scalar, dimensionless)

• n_land_ult (float) – Ultimate landing load factor, which is 1.5 times the gear load factor (defined in equation 11.11). Table 11.5 gives reasonable gear load factor values for different aircraft types, with commercial aircraft in the 2.7-3 range. Default is taken at 2.8, thus the ultimate landing load factor is 2.8 x 1.5 (scalar, dimensionless)

• control_surface_area_frac (float) – Fraction of the total wing area covered by control surfaces and flaps, by default 0.1 (scalar, dimensionless)

• fuselage_width_frac (float) – Fuselage width at horizontal tail intersection divided by fuselage diameter, by default 0.5 (scalar, dimensionless)

• K_uht (float) – Correction for all-moving tail; set to 1.143 for all-moving tail or 1.0 otherwise, by default 1.0 (scalar, dimensionless)

• elevator_area_frac (float) – Fraction of horizontal stabilizer area covered by elevators, by default 0.2 (scalar, dimensionless)

• T_tail (bool) – True if the tail is a T-tail, False otherwise

• K_door (float) – Fuselage door parameter; 1 if no cargo door, 1.06 if one side cargo door, 1.12 if two side cargo doors, 1.12 if aft clamshell door, 1.25 if two side cargo doors, and aft clamshell door, by default 1 (scalar, dimensionless)

• K_lg (float) – Fuselage-mounted landing gear parameter; 1.12 if fuselage-mounted main landing gear and 1 otherwise, by default 1 (scalar, dimensionless)

• kneeling_main_gear_parameter (float) – Set to 1.126 for kneeling main gear and 1 otherwise, by default 1 (scalar, dimensionless)

• kneeling_nose_gear_parameter (float) – Set to 1.15 for kneeling nose gear and 1 otherwise, by default 1 (scalar, dimensionless)

• K_lav (float) – Lavatory coefficient; 0.31 for short ranges and 1.11 for long ranges, by default 0.7

• K_buf (float) – Food provisions coefficient; 1.02 for short range and 5.68 for very long range, by default 4

• coeff_fc (float) – K_fc in Roskam times any additional coefficient. The book says take K_fc as 0.44 for un-powered flight controls and 0.64 for powered flight controls. Multiply this coefficient by 1.2 if leading edge devices are employed. If lift dumpers are employed, use a factor of 1.15. By default 1.2 * 0.64.

• coeff_avionics (float) – Roskam notes that the avionics weight estimates are probably conservative for modern computer-based flight management and navigation systems. This coefficient is multiplied by the Roskam estimate to account for this. By default 0.5.

• cabin_length_frac (float) – The length of the passenger cabin divided by the total fuselage length, by default 0.75.

• APU_weight_frac (float) – Auxiliary power unit weight divided by maximum takeoff weight, by deafult 0.0085.

class openconcept.weights.weights_jet_transport.WingWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Transport aircraft wing weight estimated from Raymer (eqn 15.25 in 1992 edition).

Inputs:

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|geom|wing|S_ref (float) – Wing planform reference area (scalar, sq ft)

• ac|geom|wing|AR (float) – Wing aspect ratio (scalar, dimensionless)

• ac|geom|wing|c4sweep (float) – Wing sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|wing|taper (float) – Wing taper ratio (scalar, dimensionless)

• ac|geom|wing|toverc (float) – Wing root thickness-to-chord ratio (scalar, dimensionless)

Outputs:

W_wing (float) – Estimated wing weight (scalar, lb)

Options:

• n_ult (float) – Ultimate load factor, 1.5 x limit load factor, by default 1.5 x 2.5 (scalar, dimensionless)

• control_surface_area_frac (float) – Fraction of the total wing area covered by control surfaces and flaps, by default 0.1 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.HstabConst_JetTransport(**kwargs)

Bases: ExplicitComponent

The 1 + Fw/Bh term in Raymer’s horizontal tail weight estimate (in eqn 15.26 in 1992 edition).

Inputs:

• ac|geom|hstab|S_ref (float) – Horizontal stabilizer reference area (scalar, sq ft)

• ac|geom|hstab|AR (float) – Horizontal stabilizer aspect ratio (scalar, dimensionless)

• ac|geom|fuselage|height (float) – Fuselage height (scalar, ft)

Outputs:

HstasbConst (float) – The 1 + Fw/Bh term in the weight estimate (scalar, dimensionless)

Options:

fuselage_width_frac (float) – Fuselage width at horizontal tail intersection divided by fuselage diameter, by default 0.5 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.HstabWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Horizontal stabilizer weight estimation from Raymer (eqn 15.26 in 1992 edition). This component makes the additional assumption that the distance between the wing quarter chord and horizontal stabilizer quarter chord is a constant fraction of the fuselage length (by default half).

Inputs:

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|geom|hstab|S_ref (float) – Horizontal stabilizer wing area (scalar, sq ft)

• ac|geom|hstab|AR (float) – Horizontal stabilizer aspect ratio (scalar, dimensionless)

• ac|geom|hstab|c4sweep (float) – Horizontal stabilizer sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|fuselage|length (float) – Fuselage length, used to compute distance between quarter chord of wing and horizontal stabilizer (scalar, ft)

• ac|geom|hstab|c4_to_wing_c4 (float) – Distance from the horizontal stabilizer’s quarter chord (of the MAC) to the wing’s quarter chord (scalar, ft)

• HstasbConst (float) – The 1 + Fw/Bh term in the weight estimate (scalar, dimensionless)

Outputs:

W_hstab (float) – Weight of the horizontal stabilizer (scalar, lb)

Options:

• n_ult (float) – Ultimate load factor, 1.5 x limit load factor, by default 1.5 x 2.5 (scalar, dimensionless)

• K_uht (float) – Correction for all-moving tail; set to 1.143 for all-moving tail or 1.0 otherwise, by default 1.0 (scalar, dimensionless)

• elevator_area_frac (float) – Fraction of horizontal stabilizer area covered by elevators, by default 0.2 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.VstabWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Vertical stabilizer weight estimate from Raymer (eqn 15.27 in 1992 edition). This component makes the additional assumption that the distance between the wing quarter chord and vertical stabilizer quarter chord is a constant fraction of the fuselage length (by default half).

Inputs:

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|geom|vstab|S_ref (float) – vertical stabilizer wing area (scalar, sq ft)

• ac|geom|vstab|AR (float) – vertical stabilizer aspect ratio (scalar, dimensionless)

• ac|geom|vstab|toverc (float) – vertical stabilizer thickness-to-chord ratio (scalar, dimensionless)

• ac|geom|vstab|c4sweep (float) – vertical stabilizer sweep at 25% mean aerodynamic chord (scalar, radians)

• ac|geom|vstab|c4_to_wing_c4 (float) – Distance from the vertical stabilizer’s quarter chord (of the MAC) to the wing’s quarter chord (scalar, ft)

Outputs:

W_vstab (float) – Weight of the vertical stabilizer (scalar, lb)

Options:

• n_ult (float) – Ultimate load factor, 1.5 x limit load factor, by default 1.5 x 2.5 (scalar, dimensionless)

• T_tail (bool) – True if the tail is a T-tail, False otherwise

class openconcept.weights.weights_jet_transport.FuselageKws_JetTransport(**kwargs)

Bases: ExplicitComponent

Compute Raymer’s Kws term for the fuselage weight estimation (in eqn 15.28 in the 1992 edition).

Inputs:

• ac|geom|wing|taper (float) – Main wing taper ratio (scalar, dimensionless)

• ac|geom|wing|S_ref (float) – Main wing reference area (scalar, sq ft)

• ac|geom|wing|AR (float) – Main wing aspect ratio (scalar, dimensionless)

• ac|geom|wing|c4sweep (float) – Main wing quarter chord sweep angle (scalar, radians)

• ac|geom|fuselage|length (float) – Fuselage length (scalar, ft)

Outputs:

K_ws (float) – K_ws term in Raymer’s fuselage weight approximation (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.FuselageWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Fuselage weight estimation from Raymer (eqn 15.28 in 1992 edition).

Inputs:

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|geom|fuselage|length (float) – Fuselage structural length (scalar, ft)

• ac|geom|fuselage|S_wet (float) – Fuselage wetted area (scalar, sq ft)

• ac|geom|fuselage|height (float) – Fuselage height (scalar, ft)

• K_ws (float) – Fuselage parameter computed in FuselageKws_JetTransport (scalar, dimensionless)

Outputs:

W_fuselage (float) – Fuselage weight (scalar, lb)

Options:

• n_ult (float) – Ultimate load factor, 1.5 x limit load factor, by default 1.5 x 2.5 (scalar, dimensionless)

• K_door (float) – Fuselage door parameter; 1 if no cargo door, 1.06 if one side cargo door, 1.12 if two side cargo doors, 1.12 if aft clamshell door, 1.25 if two side cargo doors, and aft clamshell door, by default 1 (scalar, dimensionless)

• K_lg (float) – Fuselage-mounted landing gear parameter; 1.12 if fuselage-mounted main landing gear and 1 otherwise, by default 1 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.MainLandingGearWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Main landing gear weight estimate from Raymer (eqn 15.29 in 1992 edition).

Inputs:

• ac|weights|MLW (float) – Maximum landing weight (scalar, lb)

• ac|geom|maingear|length (float) – Length of the main landing gear (scalar, inch)

• ac|geom|maingear|num_wheels (float) – Total number of main landing gear wheels (scalar, dimensionless)

• ac|geom|maingear|num_shock_struts (float) – Total number of main landing gear shock struts (scalar, dimensionless)

• ac|aero|Vstall_land (float) – Landing stall speed (scalar, knots)

Outputs:

W_mlg (float) – Main landing gear weight (scalar, lb)

Options:

• n_land_ult (float) – Ultimate landing load factor, which is 1.5 times the gear load factor (defined in equation 11.11). Table 11.5 gives reasonable gear load factor values for different aircraft types, with commercial aircraft in the 2.7-3 range. Default is taken at 2.8, thus the ultimate landing load factor is 2.8 x 1.5 (scalar, dimensionless)

• kneeling_gear_parameter (float) – Set to 1.126 for kneeling gear and 1 otherwise, by default 1 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.NoseLandingGearWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Nose landing gear weight estimate from Raymer (eqn 15.30 in 1992 edition).

Inputs:

• ac|weights|MLW (float) – Maximum landing weight (scalar, lb)

• ac|geom|nosegear|length (float) – Length of the nose landing gear (scalar, inch)

• ac|geom|nosegear|num_wheels (float) – Total number of nose landing gear wheels (scalar, dimensionless)

Outputs:

W_nlg (float) – Nose landing gear weight (scalar, lb)

Options:

• n_land_ult (float) – Ultimate landing load factor, which is 1.5 times the gear load factor (defined in equation 11.11). Table 11.5 gives reasonable gear load factor values for different aircraft types, with commercial aircraft in the 2.7-3 range. Default is taken at 2.8, thus the ultimate landing load factor is 2.8 x 1.5 (scalar, dimensionless)

• kneeling_gear_parameter (float) – Set to 1.15 for kneeling gear and 1 otherwise, by default 1 (scalar, dimensionless)

class openconcept.weights.weights_jet_transport.EngineWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Turbofan weight as estimated by the FLOPS weight estimation method (https://ntrs.nasa.gov/citations/20170005851). This approach adopts equation 76’s transport and HWB weight estimation method. The computed engine weight is per engine (must be multiplied by number of engines to get total engine weight).

Inputs:

ac|propulsion|engine|rating (float) – Rated thrust of each engine (scalar, lbf)

Outputs:

W_engine (float) – Engine weight (scalar, lb)

class openconcept.weights.weights_jet_transport.EngineSystemsWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Engine system weight as estimated by the FLOPS weight estimation method (https://ntrs.nasa.gov/citations/20170005851). The computed weight is for all engines (does not need to be multiplied by number of engines). The equations are from sections 5.3.3 to 5.3.5 of the linked paper. This assumes that all engines have thrust reversers and there are no center-mounted engines.

Roskam is used to estimate the engine starting system weight, assuming a pneumatic starting system and one or two get engines (eqn 6.27, Part V, 1989)

Inputs:

• ac|propulsion|engine|rating (float) – Rated thrust of each engine (scalar, lbf)

• ac|propulsion|num_engines (float) – Number of engines (scalar, dimensionless)

• ac|aero|Mach_max (float) – Maximum aircraft Mach number (scalar, dimensionless)

• ac|weights|W_fuel_max (float) – Maximum fuel weight (scalar, lb)

• W_engine (float) – Engine weight (scalar, lb)

Outputs:

• W_thrust_rev (float) – Total thrust reverser weight (scalar, lb)

• W_eng_control (float) – Total engine control weight (scalar, lb)

• W_fuelsystem (float) – Total fuel system weight including tanks and plumbing (scalar, lb)

• W_eng_start (float) – Total engine starter weight (scalar, lb)

class openconcept.weights.weights_jet_transport.NacelleWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Nacelle weight estimate from Roskam (eqn 5.37, Chapter 5, Part V, 1989).

Inputs:

• ac|propulsion|engine|rating (float) – Rated thrust of each engine (scalar, lbf)

• ac|propulsion|num_engines (float) – Number of engines (scalar, dimensionless)

Outputs:

W_nacelle (float) – Nacelle weight (scalar, lb)

class openconcept.weights.weights_jet_transport.FurnishingWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Weight estimate of seats, insulation, trim panels, sound proofing, instrument panels, control stands, lighting, wiring, galleys, lavatories, overhead luggage containers, escape provisions, and fire fighting equipment. Estimated using the General Dynamics method in Roskam (eqn 7.44, Chapter 7, Part V, 1989).

Inputs:

• ac|num_passengers_max (float) – Maximum number of passengers (scalar, dimensionless)

• ac|num_flight_deck_crew (float) – Number of flight crew members (scalar, dimensionless)

• ac|num_cabin_crew (float) – Number of flight attendants (scalar, dimensionless)

• ac|cabin_pressure (float) – Cabin pressure (scalar, psi)

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

Outputs:

W_furnishings (float) – Weight estimate of seats, galleys, lavatories, and other furnishings (scalar, lb)

Options:

• K_lav (float) – Lavatory coefficient; 0.31 for short ranges and 1.11 for long ranges, by default 0.7

• K_buf (float) – Food provisions coefficient; 1.02 for short range and 5.68 for very long range, by default 4

class openconcept.weights.weights_jet_transport.EquipmentWeight_JetTransport(**kwargs)

Bases: ExplicitComponent

Weight estimate of the flight control system, electrical system, avionics, air conditioning, pressurization system, anti-icing system, oxygen system, and APU. The estimates are all from Roskam 1989 Part V.

Inputs:

• ac|weights|MTOW (float) – Maximum takeoff weight (scalar, lb)

• ac|num_passengers_max (float) – Maximum number of passengers (scalar, dimensionless)

• ac|num_cabin_crew (float) – Number of flight attendants (scalar, dimensionless)

• ac|num_flight_deck_crew (float) – Number of flight crew members; the Roskam equation uses number of pilots, but this is the same value for modern aircraft (scalar, dimensionless)

• ac|propulsion|num_engines (float) – Number of engines (scalar, dimensionless)

• ac|geom|V_pressurized (float) – Pressurized cabin volume (scalar, cubic ft)

• W_fuelsystem (float) – Fuel system weight (scalar, lb)

Outputs:

• W_flight_controls (float) – Flight control system weight (scalar, lb)

• W_avionics (float) – Intrumentation, avionics, and electronics weight (scalar, lb)

• W_electrical (float) – Electrical system weight (scalar, lb)

• W_ac_pressurize_antiice (float) – Air conditioning, pressurization, and anti-icing system weight (scalar, lb)

• W_oxygen (float) – Oxygen system weight (scalar, lb)

• W_APU (float) – Auxiliary power unit weight (scalar, lb)

Options:

• coeff_fc (float) – K_fc in Roskam times any additional coefficient. The book says take K_fc as 0.44 for un-powered flight controls and 0.64 for powered flight controls. Multiply this coefficient by 1.2 if leading edge devices are employed. If lift dumpers are employed, use a factor of 1.15. By default 1.2 * 0.64.

• coeff_avionics (float) – Roskam notes that the avionics weight estimates are probably conservative for modern computer-based flight management and navigation systems. This coefficient is multiplied by the Roskam estimate to account for this. By default 0.5.

• APU_weight_frac (float) – APU weight divided by maximum takeoff weight, by deafult 0.0085.