massprop_feathers {AvInertia}

Feather mass properties

Description

Calculate the moment of inertia of the feathers within the feather frame of reference.

Usage

massprop_feathers(
  m_f,
  l_c,
  l_r_cor,
  w_cal,
  r_b,
  d_b,
  rho_cor,
  rho_med,
  w_vp,
  w_vd,
  angle
)

Arguments

m_f

Mass of the entire feather (kg)

l_c

Length of the calamus; start of vane to end of calamus(m)

l_r_cor

Length of rachis; tip to start of vane (m)

w_cal

Width (diameter) of the cortex part of the calamus (m)

r_b

Radius of feather barbs (m)

d_b

Distance between barbs (m)

rho_cor

Density of the cortex (kg/m^3)

rho_med

Density of the medullary (kg/m^3)

w_vp

Width of proximal (closest to body) vane (m)

w_vd

Width of distal (closest to wing tip) vane (m)

angle

Angle between calamus and the vane taken the supplement angle to the interior angle. Negative indicates the feather tip is rotated proximally relative to the start of the feather vane.

Value

a list that includes:

• Ia 3x3 matrix representing the moment of inertia tensor of a simplified feather with the origin at the feather calamus end and within the feather frame of reference

• CGa 1x3 vector representing the center of gravity position of a simplified feather with the origin at the feather calamus end and within the feather frame of reference

• ma double that returns the feather mass

Warning

Parallel axis theorem does not apply between two arbitrary points. One point must be the object's center of gravity.

CAUTION: While computing the variable components of the feather the x axis is the normal of the feather.

Author(s)

Christina Harvey

Examples

# refer to the vignette
library(AvInertia)

# load data
data(dat_id_curr, package = "AvInertia")
data(dat_bird_curr, package = "AvInertia")
data(dat_feat_curr, package = "AvInertia")
data(dat_bone_curr, package = "AvInertia")
data(dat_mat, package = "AvInertia")
data(clean_pts, package = "AvInertia")

# 1. Determine the center of gravity of the bird's torso (including the legs)
dat_torsotail_out = massprop_restbody(dat_id_curr, dat_bird_curr)
# 2. Calculate the inertia of the flight feathers about the tip of the calamus
feather_inertia <- compute_feat_inertia(dat_mat, dat_feat_curr, dat_bird_curr)
# 3. Determine the center of gravity of one of the bird's wings
dat_wing_out      = massprop_birdwing(dat_id_curr, dat_bird_curr,
dat_bone_curr, dat_feat_curr, dat_mat, clean_pts,
feather_inertia, plot_var = 0)
# Visualize the center of gravity of each wing component in the x and y axis
dat_wing_out      = massprop_birdwing(dat_id_curr, dat_bird_curr,
dat_bone_curr, dat_feat_curr, dat_mat, clean_pts,
feather_inertia, plot_var = "yx")
# or the y and z axis
dat_wing_out      = massprop_birdwing(dat_id_curr, dat_bird_curr,
dat_bone_curr, dat_feat_curr, dat_mat, clean_pts,
feather_inertia, plot_var = "yz")
# 4. Combine all data and obtain the center of gravity, moment of inertia
# and principal axes of the bird
curr_full_bird      = combine_inertialprop(dat_torsotail_out,dat_wing_out,
dat_wing_out, dat_id_curr, dat_bird_curr, symmetric=TRUE)