massprop_feathers {AvInertia} R Documentation

## 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.

Christina Harvey

### Examples

```# refer to the vignette
library(AvInertia)

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)

```

[Package AvInertia version 0.0.1 Index]