AnnexFParms¶
This class provides support for redoing some of the computations found in Annex F [1].
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class
casex.annex_f_parms.AnnexFParms[source]¶ This class contains the following parameters for the 5 size classes in the iGRC table:
- Parameters
impact_angle (float) – [deg] The impact angle of the descending aircraft, relative to horizontal.
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aircraft¶ The class containing information about the aircraft.
- Type
AircraftSpecs
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aircraft_type¶ The type of aircraft. This parameters is not currently used.
- Type
enums.AircraftType
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critical_area_target¶ [m^2] Size of the largest critical area for each size class.
- Type
float
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ballistic_descent_altitude¶ [m] Assumed altitude for beginning of ballistic descent.
- Type
float
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ballistic_descent_time¶ [s] Computed descent time for ballistic descent.
- Type
float
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ballistic_distance¶ [m] Computed horizontal distance traveled during ballistic descent.
- Type
float
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ballistic_drag_coefficient = 0.8 [-] Drag coefficient used for ballistic descent.
- Type
float
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ballistic_frontal_area¶ [m^2] Assumed frontal area used in ballistic computations.
- Type
float
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ballistic_impact_angle¶ [deg] Computed impact angle with 0 being horizontal.
- Type
float
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ballistic_impact_KE¶ [J] Computed kinetic energy of aircraft just prior to impact.
- Type
float
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ballistic_impact_velocity¶ [m/s] Assumed horizontal velocity for beginning of ballistic descent.
- Type
float
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cruise_speed¶ [m/s]Maximum cruise speed for each size class.
- Type
float
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friction_coefficient = 0.65 [-] The friction coefficient is assumed constant at 0.65 throughout Annex F [1].
- Type
float
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glide_reduce = 0.65 [-] Reduction in glide speed relative to cruise speed.
- Type
float
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glide_speed¶ [m/s] The glide speed resulting from multiplying the cruise speed by glide_reduce.
- Type
float
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impact_angle¶ [deg] The impact angle of the aircraft when crashing, measure relative to horizontal.
- Type
float
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KE_critical¶ [J] Non-lethal energy during slide.
- Type
float
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mass¶ [kg] Assumed biggest mass for each size class.
- Type
float
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population_bands = [0.25 25 250 2500 25000 250000] [ppl/km2] The population density bands used for the iGRC.
- Type
float array
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scenario_angles = [10, 35, 62] [deg] The three impact angles for the three descent scenarios. The 62 degrees is not actually used but recomputed for each ballistic descent.
- Type
float array
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terminal_velocity¶ [m/s] Terminal velocity for aircraft.
- Type
float
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wingspan¶ Characteristic dimension of the aircraft. See Annex F [1] for more detailed explanation on what that is.
- Type
float
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static
CoR_from_impact_angle(impact_angle, angles=None, CoRs=None)[source]¶ Compute a coefficient of restitution for a given impact angle.
This method assumes an affine relation between impact angle and CoR. Therefore, two angles and two CoR values are used to determine this relation. The default is as described in Annex F that the CoR is 0.8 at a 10 degree impact and 0.6 at a 90 degree (vertical) impact. This values are used as defaults, but others can be specified.
- Parameters
impact_angle (float) – [deg] The impact angle between 0 and 90.
angles (float array, optional) – [deg] Array with two different angle of impact values (the default is [10, 90]).
CoRs (float array, optional) – [-] Array with two COR values corresponding to the two angles (the default is [0.8, 0.6]).
- Returns
coefficient of restitution – [-] The coefficient of restitution for the given impact angle.
- Return type
float
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static
applied_obstacle_reduction_factor(width)[source]¶ Compute the obstacle reduction factor used in the iGRC in Annex F [1].
- Parameters
pop_dens (float) – [ppl/km^2] Population density
- Returns
obstacle_reduction_factor – The reduction factor for use in iGRC.
- Return type
float
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static
iGRC(pop_dens, CA, TLOS=1e-06, use_conservative_compensation=False)[source]¶ Compute the finale integer iGRC as described in Annex F [1].
This method computes the integer and the raw iGRC values for a given population density and size of critical area. The TLOS, target level of safety, can also be set, but the default value is \(10^{-6}\) as described in Annex F [1].
Note
This method converts the population density to ppl/m^2 as needed for the equation. This is because the unit for the input is ppl/km^2, since this is typically how the density is known.
- Parameters
pop_dens (float) – [ppl/km^2] Population density
CA (float) – [m^2] Size of the critical area.
TLOS (float, optional) – [fatalities per flight hour] Target level of safety (the default is 1e-6). This value is described in more detail in Annex F [1].
use_conservative_compensation (bool, optional) – if True, the 0.3 reduction in iGRC value is applied.
- Returns
iGRC (integer) – The intrinsic ground risk class (as an integer). This is the raw value rounded up to nearest integer.
raw iGRC (float) – The raw iGRC before rounding up.