Will my bird likely be able to fly in this atmosphere on this planet?

I'm working on a species of large bird, and trying to determine whether they will be able to fly or not.

I know that this equation likely applies:

$$ A = \cfrac{L}{\cfrac{1}{2} v^2 \rho C_L} $$

where $A$ is (wing) surface area, $L$ is lift force, $v$ is speed, $\rho$ is air density, and $C_L$ is coefficient of lift.

For an Earth-like planet, specifically one with Earth-like gravity, applying this would be relatively straight forward, as already illustrated in the linked answer. However, my planet has a different gravity! Specifically, the surface gravitational acceleration is a shade over 12.2 m/s², corresponding to about 1.25 G, which (unfortunately in this case, but deliberately chosen) amounts to a rather significant difference.

The atmospheric pressure on the surface is 1930 millibar, compared to Earth's just over 1013 millibar in a standard atmosphere. These birds fly at such altitudes that, as an approximation, their atmosphere can be assumed to be uniformly at that pressure.

The birds don't need to be fast flyers -- I'd be happy with 15-20 km/h in level flight, though I don't mind it at all if they can be faster.

However, they are big. My current design has the wing span of a large one at up to 300 cm tip to tip (compared to e.g. a bald eagle's typical up to 230 cm), 80 cm from the beak to the tail feathers, and a mass (not weight) of 13 kg (up to three times that of a harpy eagle). On Earth, that corresponds to a shade over 127 N (13 kgf); with the higher gravity, that'd be 159 N (about 16.2 kgf?) of force directed toward ground. By simplifying (in the manner of the spherical cows of physics), I estimated the total wing surface area of a large bird to be about 15000 cm².

• How do I apply the above equation to a non-unity gravity? (What is the actual unit of $L$?)
• If the above equation doesn't apply in non-unity gravity, what formula do I need?
• Will my birds likely be able to fly in the specified environment?

posted over 6 years ago

Canina‭

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