Adding an aircraft concept

A new propulsion architecture requires three declarations in noads/application/base_objects.py, plus its energy supply chain (see energy pathways) if it embarks a carrier that does not exist yet. The liquid-methane gas turbine below is used as the running example; the hooks for it are already present as commented-out code in the repository.

1. Declare the architecture

Add an entry to propulsion_architectures (the power system passed to the Generic Airplane Model) and to propulsion_mission (the cruise conditions):

propulsion_architectures = {
    # ...
    "lCH4-GasTurbine": {
        "engine_count": 2,
        "engine_type": "turbofan",
        "thruster_type": "fan",
        "energy_type": "liquid_ch4",
        "bpr": 12.0,
    },
}

propulsion_mission = {
    # ...
    "lCH4-GasTurbine": {"speed": 0.8 * 340, "altitude": 28000 * 0.3048},
}

The energy_type must be one supported by the Generic Airplane Model (GAM), which handles the propulsion-system weight (tanks, fuel cells, motors, batteries) as a function of the aircraft technology parameters.

2. Declare the energy carrier and its propulsion system

Inside initialize_base_objects, create the final energy carrier with its physical properties and production pathways, and map the architecture to a PropulsionSystem consuming it:

# Gas methane, produced by three competing pathways
fossil_ch4 = ProductionPathway("GM_fossil", impacts=[], input_streams=[natural_gas])
ptg = ProductionPathway("GM_methanation", impacts=[], input_streams=[gh2])
biogas = ProductionPathway("GM_biogas", impacts=[co2], input_streams=[biomass])
gch4 = ProducedEnergy("GAS-CH4", pathways=[ptg, biogas, fossil_ch4])

# Liquefaction into the final carrier embarked by the aircraft
gch4_liquefaction = ProductionPathway(
    "LM_liquefaction", impacts=[], input_streams=[electricity, gch4]
)
lch4 = ProducedEnergyCarrier(
    "LIQUID-CH4",
    pathways=[gch4_liquefaction],
    density=22.2 / 53.6,      # kg/L over MJ/kg -> used for tank sizing
    specific_energy=53.6,     # MJ/kg
)

energies.extend([gch4, lch4])
prop_systems.update({
    "lCH4-GasTurbine": PropulsionSystem("lch4_burn", {lch4: 1.0}),
})

initialize_base_objects then automatically creates one AircraftDesign per market for the new architecture, together with its entry-into-service and maximum market share optimization variables.

3. Provide the pathway coefficients

The numeric efficiencies and direct emission indices of the new pathways are plain scenario inputs, set in the constants dictionary of noads/application/scenario_setup.py with the naming convention "<pathway>.<input>.efficiency" and "<pathway>.direct.CO2_index":

constants.update({
    "NATURAL_GAS.CO2_index": 67.6,
    "GM_methanation.direct.CO2_index": 0.0,
    "GM_biogas.direct.CO2_index": 14.3,
    "GM_fossil.direct.CO2_index": 0.0,
    "LM_liquefaction.direct.CO2_index": 0.0,
    "GM_fossil.NATURAL_GAS.efficiency": 1.0,
    "GM_methanation.GAS-H2.efficiency": 0.89,
    # ...
})

Efficiencies maturing in time are declared in interpolated_2025_2035_2050 instead, as (2025, 2035, 2050) triplets that are linearly interpolated.

4. Run and inspect

Re-run any scenario, for example with single_policy_scenario_optimization() and load_optimum=False. The optimizer will now trade the new architecture off against the others in every market where its design is feasible. The fleet plots of noads.application.visualization pick up new aircraft automatically from the fleet assembly.

Tip

If the new carrier competes for a constrained resource (biomass, electricity), no extra work is needed: the resource constraints are generated from EnergyMix(..., inputs_to_constrain=[electricity, biomass]). To constrain a new primary resource, see energy pathways and resources.