Birds

Storyboard

Birds have a very unique way of flying that sets them apart from the techniques used by humans in their aircraft. In this case, the wings serve a dual purpose, generating both lift and thrust, even when the bird is stationary.

>Model

ID:(2056, 0)


Mechanisms

Description


ID:(15178, 0)


Pigeon flight study, side view

Description

If you study the video of a pigeon flying from a lateral perspective, you can observe how it advances and retracts its wings.

None



During the forward phase, the bird manages to generate lift, while during the backward phase, it seeks propulsion.

ID:(1587, 0)


Pigeon flight study, front view

Description

If you study the video of a pigeon flying from a frontal perspective, you can observe how it extends and retracts its wings.

None



During the forward phase, the bird extends its wings for the first time to generate lift, while during the backward phase, it extends them for the second time to propel itself forward.

ID:(1589, 0)


Wing shape

Description

To model the wing, we need to estimate the wing span ($L$), the width the wing width ($w$), and the wing height ($d$) of the wing in order to calculate the surface that generates lift ($S_w$) and the total object profile ($S_p$). An article with data for migratory birds can be found in [1]:

Bird $m$ [kg] $S_w$ [m2] $L$ [m] $\Delta$ [m]
Stonechat 0.0232 0.01366 0.264 0.052
Meadow Pipit 0.0199 0.0143 0.273 0.052
Nightingale 0.0197 0.01059 0.221 0.048
Barn Swallow 0.0182 0.01446 0.328 0.044
Robin 0.0182 0.01026 0.224 0.046
Yellow Wagtail 0.0176 0.01051 0.248 0.042
Spotted Flycatcher 0.0153 0.01209 0.262 0.046
Black Redstart 0.015 0.01006 0.200 0.050
Garden Warbler 0.0123 0.00779 0.200 0.039
Pied Flycatcher 0.012 0.00873 0.200 0.044
Serin 0.0114 0.00828 0.214 0.039
Garden Warbler 0.0087 0.00768 0.194 0.040
Goldcrest 0.0054 0.00504 0.146 0.035



Note: In this case, wing areas and spans are provided, so the width can be estimated as $S_w/L$. Similarly, the wing height can be estimated from the profile area divided by the span $S_p/L$, although in this case, we are not considering that the profile includes the bird's body section.

[1] "Field Estimates of Body Drag Coefficient on the basis of dives in passerine Birds," Anders Hedenström, Felix Liechti, The Journal of Experimental Biology, 204, 1167-1175 (2001).

ID:(1585, 0)


Example of wing factors

Description

When we compare different types of wings, we notice that raptors tend to have shorter and broader wings, whereas migratory birds have longer and narrower ones. Therefore, it makes sense to define the aspect Ratio ($\gamma_w$) as the relationship between the wing span ($L$) and the wing width ($w$):

None

ID:(7043, 0)


Model

Description


ID:(15191, 0)


Birds

Description

Birds have a very unique way of flying that sets them apart from the techniques used by humans in their aircraft. In this case, the wings serve a dual purpose, generating both lift and thrust, even when the bird is stationary.

Variables

Symbol
Text
Variable
Value
Units
Calculate
MKS Value
MKS Units
$\gamma_w$
gamma_w
Aspect Ratio
-
$S_w$
S_w
Surface that generates lift
m^2
$\gamma_d$
gamma_d
Thickness to span ratio
-
$S_p$
S_p
Total object profile
m^2
$d$
d
Wing height
m
$L$
L
Wing span
m
$w$
w
Wing width
m

Calculations


First, select the equation:   to ,  then, select the variable:   to 

Symbol
Equation
Solved
Translated

Calculations

Symbol
Equation
Solved
Translated

 Variable   Given   Calculate   Target :   Equation   To be used



Equations

As the power of flight ($P$) is related to the density ($\rho$), the total object profile ($S_p$), the coefficient of resistance ($C_W$), the body mass ($m$), the gravitational Acceleration ($g$), the proportionality constant coefficient sustainability ($c$), the surface that generates lift ($S_w$), and the speed with respect to the medium ($v$) through

$ P =\displaystyle\frac{1}{2} \rho S_p C_W v ^3 + \displaystyle\frac{2 m ^2 g ^2}{ c ^2 S_w \rho }\displaystyle\frac{1}{ v }$

,

with the definitions of the surface that generates lift ($S_w$) in terms of the wing width ($w$)

$ S_w = L \Delta $

,

and the aspect Ratio ($\gamma_w$)

$ \gamma_w =\displaystyle\frac{ w }{ L }$

,

along with the aircraft body mass ($m_p$) in relation to the wing height ($d$)

$ S_p = L \delta $

,

and the thickness to span ratio ($\gamma_d$)

$ \gamma_r =\displaystyle\frac{ d }{ w }$

,

finally, as

$ P_w =\displaystyle\frac{1}{2} \rho L ^2 C_w v ^3\displaystyle\frac{1}{ \gamma_p }+\displaystyle\frac{2 m ^2 g ^2}{ c ^2 L ^2 \rho } \gamma_w \displaystyle\frac{1}{ v }$

.

(ID 9593)


Examples


(ID 15178)

If you study the video of a pigeon flying from a lateral perspective, you can observe how it advances and retracts its wings.

None



During the forward phase, the bird manages to generate lift, while during the backward phase, it seeks propulsion.

(ID 1587)

If you study the video of a pigeon flying from a frontal perspective, you can observe how it extends and retracts its wings.

None



During the forward phase, the bird extends its wings for the first time to generate lift, while during the backward phase, it extends them for the second time to propel itself forward.

(ID 1589)

To model the wing, we need to estimate the wing span ($L$), the width the wing width ($w$), and the wing height ($d$) of the wing in order to calculate the surface that generates lift ($S_w$) and the total object profile ($S_p$). An article with data for migratory birds can be found in [1]:

Bird $m$ [kg] $S_w$ [m2] $L$ [m] $\Delta$ [m]
Stonechat 0.0232 0.01366 0.264 0.052
Meadow Pipit 0.0199 0.0143 0.273 0.052
Nightingale 0.0197 0.01059 0.221 0.048
Barn Swallow 0.0182 0.01446 0.328 0.044
Robin 0.0182 0.01026 0.224 0.046
Yellow Wagtail 0.0176 0.01051 0.248 0.042
Spotted Flycatcher 0.0153 0.01209 0.262 0.046
Black Redstart 0.015 0.01006 0.200 0.050
Garden Warbler 0.0123 0.00779 0.200 0.039
Pied Flycatcher 0.012 0.00873 0.200 0.044
Serin 0.0114 0.00828 0.214 0.039
Garden Warbler 0.0087 0.00768 0.194 0.040
Goldcrest 0.0054 0.00504 0.146 0.035



Note: In this case, wing areas and spans are provided, so the width can be estimated as $S_w/L$. Similarly, the wing height can be estimated from the profile area divided by the span $S_p/L$, although in this case, we are not considering that the profile includes the bird's body section.

[1] "Field Estimates of Body Drag Coefficient on the basis of dives in passerine Birds," Anders Hedenstr m, Felix Liechti, The Journal of Experimental Biology, 204, 1167-1175 (2001).

(ID 1585)

When we compare different types of wings, we notice that raptors tend to have shorter and broader wings, whereas migratory birds have longer and narrower ones. Therefore, it makes sense to define the aspect Ratio ($\gamma_w$) as the relationship between the wing span ($L$) and the wing width ($w$):

None

(ID 7043)


(ID 15191)

The surface that generates lift ($S_w$) can be estimated using the wing span ($L$) and the wing width ($w$) as follows:

$ S_w = L \Delta $

(ID 4553)

The total object profile ($S_p$) can be estimated using the wing span ($L$) and the wing height ($d$) as follows:

$ S_p = L \delta $

(ID 4554)

The aspect Ratio ($\gamma_w$) is defined as the ratio between the wing width ($w$) and the wing span ($L$), indicating the proportion or relationship between these two variables:

$ \gamma_w =\displaystyle\frac{ w }{ L }$

(ID 4551)

The aspect Ratio ($\gamma_w$) can be defined as the thickness to span ratio ($\gamma_d$), which relates the wing width ($w$) to ERROR:6338

$ \gamma_r =\displaystyle\frac{ d }{ w }$

(ID 4555)

Just as the power of flight ($P$) is related to the density ($\rho$), the total object profile ($S_p$), the coefficient of resistance ($C_W$), the body mass ($m$), the gravitational Acceleration ($g$), the proportionality constant coefficient sustainability ($c$), the surface that generates lift ($S_w$), and the speed with respect to the medium ($v$) through

$ P =\displaystyle\frac{1}{2} \rho S_p C_W v ^3 + \displaystyle\frac{2 m ^2 g ^2}{ c ^2 S_w \rho }\displaystyle\frac{1}{ v }$

,

we can express the power in terms of the aspect Ratio ($\gamma_w$) and the thickness to span ratio ($\gamma_d$) as

$ P_w =\displaystyle\frac{1}{2} \rho L ^2 C_w v ^3\displaystyle\frac{1}{ \gamma_p }+\displaystyle\frac{2 m ^2 g ^2}{ c ^2 L ^2 \rho } \gamma_w \displaystyle\frac{1}{ v }$

.

(ID 9593)


ID:(2056, 0)