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Core Engine

The rusty_runways_core crate implements all game rules and the event‑driven simulation. It is I/O‑free and can be embedded in different frontends (CLI, GUI, Python).

Core Concepts

  • Game state (Game): time, player, airplanes, airports, scheduled events, and logs.
  • Airports: name, coordinates, fees, runway length, dynamic fuel price, and outstanding orders.
  • Airplanes: model, specs, location, status, manifest, and operational costs.
  • Orders: either cargo (type, weight) or passenger groups (count), plus value, deadline, origin, destination.
  • Player: cash, fleet, deliveries; can buy planes subject to constraints.

Game Rules

  • Time advances in integer hours. Many actions (load, unload, refuel, maintenance) consume one hour.
  • Deadlines are tracked in hours. Delivering after a deadline is considered a failure (penalties are handled in the engine’s accounting/events layer).
  • Airports charge fuel by liter and fees (parking/landing) based on usage and mass.
  • Airplane movement is constrained by range and runway length at both origin and destination.

Loading, Unloading, Refueling

  • Load order: Game::load_order(order_id, plane_id)
  • Requires the plane to be parked at an airport that holds the order.
  • Checks payload capacity; schedules a loading event (+1h).
  • Unload orders
  • unload_order(order_id, plane_id) for a single order.
  • unload_all(plane_id) to empty the manifest.
  • Schedules unloading events (+1h).
  • Refuel plane: refuel_plane(plane_id) schedules refueling (+1h) and charges the price per liter at the airport.

Passing of Time

  • advance(hours) progresses the simulation by the requested amount or until the next event.
  • Events include arrivals, load/unload completions, maintenance, deadlines, and breakdowns.
  • The engine accrues income and expenses (operating costs, purchases) as time passes and actions occur.

World Generation (Seedable)

  • A new game is created via Game::new(seed, num_airports, starting_cash).
  • The world uses deterministic PRNG seeding:
  • Airports (positions, names, fees, runway lengths) are generated based on the seed and num_airports.
  • Orders originate at airports with randomized types, weights, deadlines, and destinations.
  • The same seed produces the same world layout and initial orders.

Maintenance

  • Airplanes can be set to maintenance (maintenance_on_airplane(plane_id)), which takes time and can prevent breakdowns.
  • Skipping routine checks increases the risk of failures (modeled by the engine), grounding planes and delaying operations.

Fuel Prices

  • Each airport has a fuel price per liter. Refueling charges depend on the quantity and local pricing.
  • Dynamic pricing nudges prices up or down by the configured elasticity each fuel_interval_hours, clamped between the configured minimum and maximum multipliers of the airport's base price.
  • Strategy: refuel where cheaper, accounting for range, payload, and deadlines.

Airplanes

All models (see utils::airplanes::models):

  • SparrowLight – short-range combi prop
  • FalconJet – light biz jet (passenger)
  • CometRegional – regional turbofan (passenger)
  • Atlas – narrow-body combi
  • TitanHeavy – wide-body freighter (cargo)
  • Goliath – super-heavy freighter (cargo)
  • Zephyr – long-range twin-aisle (passenger)
  • Lightning – supersonic small jet (passenger)
  • BisonFreighter – medium cargo hauler
  • TrailblazerCombi – high-capacity combi aircraft

Each model exposes specs via AirplaneModel::specs() including:

  • MTOW, cruise speed (km/h), fuel capacity (L), fuel consumption (L/h), operating cost ($/h), cargo payload capacity (kg), passenger capacity (seats), model role (cargo/passenger/mixed), purchase price, and computed minimum runway length (m).
  • Players may sell a parked, empty airplane back to the market for 60% of its purchase price.

Custom Airplane Catalog (YAML)

Scenarios can replace or extend the built‑in airplane catalog via the world YAML. Add an airplanes block at the top level:

airplanes:
  strategy: replace   # or: add (default)
  models:
    - name: WorkshopCombi
      mtow: 15000.0
      cruise_speed: 520.0
      fuel_capacity: 3200.0
      fuel_consumption: 260.0
      operating_cost: 950.0
      payload_capacity: 3200.0
      passenger_capacity: 24
      purchase_price: 780000.0
      min_runway_length: 1200.0
      role: Mixed        # Cargo | Passenger | Mixed
  • strategy=replace uses only the declared models. strategy=add merges them with defaults.
  • All fields are required. Validation enforces positive values and role‑specific capacities:
  • Cargo requires payload_capacity > 0
  • Passenger requires passenger_capacity > 0
  • Mixed requires both > 0

Games started from this YAML will list these models in the CLI, Python, and Tauri UI and allow buying them by name.

Landing Constraints and Derivation

Minimum runway length is derived from simplified physics based on the airplane’s cruise speed, assumed takeoff speed (~0.65·cruise), acceleration, and deceleration:

  • Takeoff distance: v² / (2a) with a ≈ 2.5 m/s².
  • Landing distance: v² / (2d) with d ≈ 4.0 m/s².
  • The required runway length is the max of the two. Airports must meet this requirement to allow takeoff/landing for a model.