aerosandbox.library.field_lengths#

Module Contents#

Functions#

field_length_analysis_torenbeek(design_mass_TOGW, ...)

Performs a field length analysis on an aircraft, returning a dictionary of field length parameters.

field_length_analysis(design_mass_TOGW, ...[, ...])

Attributes#

results

aerosandbox.library.field_lengths.field_length_analysis_torenbeek(design_mass_TOGW, thrust_at_liftoff, lift_over_drag_climb, CL_max, s_ref, n_engines, atmosphere=None, CD_zero_lift=0.03, obstacle_height=35 * u.foot, friction_coefficient=0.02, V_obstacle_over_V_stall=1.3, minimum_V_liftoff_over_V_stall=1.2, V_approach_over_V_stall=1.3, maximum_braking_deceleration_g=0.37, inertia_time=4.5, approach_angle_deg=3)[source]#

Performs a field length analysis on an aircraft, returning a dictionary of field length parameters.

Citations:

  • “Torenbeek”: Egbert Torenbeek, “Synthesis of Subsonic Airplane Design”, 1976. (Generally, section 5.4.5:

Takeoff)

Parameters:

  • design_mass_TOGW (float) – The takeoff gross weight of the entire aircraft [kg].

  • thrust_at_liftoff (float) – The thrust of the aircraft at the moment of liftoff [N].

  • lift_over_drag_climb (float) – The lift-to-drag ratio of the aircraft during the climb phase of takeoff [dimensionless].

  • CL_max (float) – The maximum lift coefficient of the aircraft [dimensionless]. Assumes any lift-augmentation devices (

  • e.g. –

  • slats –

  • deployed. (flaps) are) –

  • s_ref (float) – The reference area of the aircraft [m^2].

  • atmosphere (aerosandbox.Atmosphere) – The atmosphere object to use for the analysis. Defaults to sea level.

  • n_engines (int) – The number of engines on the aircraft. Used during balanced field length calculation,

  • assumption. (which involves a single-engine-failure) –

  • CD_zero_lift (float) – The zero-lift drag coefficient of the aircraft [dimensionless].

  • obstacle_height (float) –

    The height of the obstacle clearance [m].

    Note

    • FAR 23 requires a 50 foot obstacle clearance height.

    • FAR 25 requires a 35 foot obstacle clearance height.

  • friction_coefficient (float) –

    The coefficient of friction between the wheels and the runway.

    • 0.02 is a good value for a dry concrete runway.

    • 0.045 is a good value for short grass.

  • V_obstacle_over_V_stall (float) – The ratio of the airspeed while flying over the obstacle to the stall airspeed.

  • minimum_V_liftoff_over_V_stall (float) – The minimum-allowable ratio of the liftoff airspeed to the stall airspeed.

  • V_approach_over_V_stall (float) – The ratio of the approach airspeed to the stall airspeed.

  • maximum_braking_deceleration_g (float) –

    The maximum deceleration of the aircraft during braking [G].

    This is used when calculating the “brake” portion of the “accelerate-brake” balanced field length, as well as the braking during normal landing.

    • Standard brakes are around 0.37 G on dry concrete.

    • Advanced brakes with optimum brake pressure control, lift dumpers, and nosewheel braking can be as high

    as 0.5 G on dry concrete.

  • inertia_time (float) – The time it takes for the pilot and aircraft to collectively react to an engine failure during

  • of (takeoff [seconds]. This is collectively the sum) –

    • The pilot’s reaction time

    • The time it takes the other engines to spool down, in the event of a rejected takeoff and deceleration

    on the ground.

  • approach_angle_deg (float) –

Returns:

  • “takeoff_ground_roll_distance”: The distance the aircraft will roll on the ground during a normal

takeoff before liftoff [meters].

  • ”takeoff_airborne_distance”: The distance the aircraft will travel in the air during a normal takeoff [

meters]. This is after liftoff, but before the aircraft has reached the obstacle clearance height.

  • ”takeoff_total_distance”: The total field length required during a normal takeoff [meters]. This

includes both the ground roll itself, as well as the airborne distance before the obstacle clearance height is reached.

  • ”balanced_field_length”: The field length required for takeoff and obstacle clearance when one engine

fails at “decision speed” [meters]. Decision speed is the speed during the ground roll at which, if an engine fails, the aircraft can either continue the takeoff or brake to a complete stop in the same total distance.

  • ”landing_airborne_distance”: The distance the aircraft will travel in the air during a normal landing

before touchdown [meters]. Note that a normal landing involves passing the runway threshold at the specified obstacle clearance height.

  • ”landing_ground_roll_distance”: The distance the aircraft will roll on the ground after touchdown

during a normal landing [meters].

  • ”landing_total_distance”: The total field length required during a normal landing [meters]. This

includes both the airborne distance beyond the threshold that is required for obstacle clearance, as well as the ground roll distance after touchdown.

  • ”V_stall”: The stall speed of the aircraft at its takeoff gross weight [m/s].

  • ”V_liftoff”: The airspeed at the moment of liftoff during a normal takeoff [m/s].

  • ”V_obstacle”: The airspeed when the aircraft reaches the obstacle clearance height during a normal

takeoff [m/s].

  • ”V_approach”: The airspeed when the aircraft reaches the runway threshold during a normal landing.

  • ”V_touchdown”: The airspeed when the aircraft touches down during a normal landing.

  • ”flight_path_angle_climb”: The flight path angle during a normal takeoff at the point when the airplane

reaches the obstacle clearance height [radians].

  • ”flight_path_angle_climb_one_engine_out”: The flight path angle during a critical-engine-out takeoff at

the point when the airplane reaches the obstacle clearance height [radians]. If this number is negative, engine failure results in inability to climb.

Return type:

A dictionary of field length parameters, including

aerosandbox.library.field_lengths.field_length_analysis(design_mass_TOGW, thrust_at_liftoff, lift_over_drag_climb, CL_max, s_ref, n_engines, V_engine_failure_balanced_field_length, atmosphere=None, CD_zero_lift=0.03, obstacle_height=35 * u.foot, friction_coefficient=0.02, minimum_V_liftoff_over_V_stall=1.2, maximum_braking_deceleration_g=0.37, inertia_time=2, approach_angle_deg=3)[source]#
Parameters:

  • design_mass_TOGW (float) –

  • thrust_at_liftoff (float) –

  • lift_over_drag_climb (float) –

  • CL_max (float) –

  • s_ref (float) –

  • n_engines (int) –

  • V_engine_failure_balanced_field_length (float) –

  • atmosphere (aerosandbox.Atmosphere) –

  • CD_zero_lift (float) –

  • obstacle_height (float) –

  • friction_coefficient (float) –

  • minimum_V_liftoff_over_V_stall (float) –

  • maximum_braking_deceleration_g (float) –

  • inertia_time (float) –

  • approach_angle_deg (float) –

Return type:

Dict[str, float]

aerosandbox.library.field_lengths.results[source]#