I've been searching here at the WBSE (I hope this acronym is correct and doesn't offend anyone) for answers on how a pegasus could be scientifically correct and I found these post: Anatomically Correct Pegasus. It says that the pegasus would have wings of 10 meters and would not be strong enough to lift a human. But I remembered what I was told in a Quora question: increasing the air density allows for larger flying beings to exist as more nitrogen makes flying easier and in my world the air density will be higher than Earth's(twice as much). So here's the question: could a pegasus be light enough to fly and still strong enough to carry a person even in such an atmosphere?

Some points about my pegasus:

  • It is herbivore;
  • Has both fur and feathers (but I accept suggestions for changes);
  • Can handle carrying an average human being during flight.
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    $\begingroup$ What are the parameters of your atmosphere? "Higher pressure than on Earth" is a bit vague to draw any answer out of it $\endgroup$
    – L.Dutch
    Sep 30, 2021 at 8:47
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    $\begingroup$ How fast is a dragon? $\endgroup$ Sep 30, 2021 at 8:49
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    $\begingroup$ Unless you're going for sci-fi-fantasy (that just happens to have some beasts that resemble common fantasy-fantasy beasts) rather than fantasy-fantasy it's probably best not to sweat the details too much, if you've any magic at all in your world you can just ignore most small problems & say they have a little natural magic (specific only to their ability to fly) if anyone asks but it's not worth telling people that if they don't ask (if they don't ask you're just breaking immersion & padding words to no good purpose). $\endgroup$
    – Pelinore
    Sep 30, 2021 at 10:34
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    $\begingroup$ @ARogueAnt. -- Both a pegasus and a dragonus fly at the speed of thought. Now, as the speed of thought depends on the thinker, a pegasus will fly faster than a dragonus, because pegasuses were thought by the smart and inventive (some even say cunning) Greeks, whereas dragonuses not so much. $\endgroup$
    – AlexP
    Sep 30, 2021 at 11:28
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    $\begingroup$ Give it a magic horn that makes it supernaturally fly, and the wings are essentially just mating plumage for attraction. But, could a pegasus be light enough to fly and still strong enough to carry a person even in such an atmosphere? Sure. If you’re just changing the atmosphere, change it so the Pegasus can carry a person too and leave it at that. $\endgroup$ Sep 30, 2021 at 15:39

2 Answers 2


A bunch of important things to do with flight of any kind scale linearly with atmosphere density... dynamic pressure is an important one (which in turn affects lift and drag).

This means that if you were able to double the density of your atmosphere, all sorts of things get twice as easy... flapping might develop twice the force, and wings can be smaller or gliding can be more efficient, etc etc. Unfortunately it also means that more force is required to push your way through the thicker atmosphere... there's no such thing as a free lunch.

All the problems of aerodynamics will still apply, and horses aren't really quite as streamlined as birds are even before you put a lumpy human with a giant draggy cross-section on their back. Classical dragons look a wee bit more streamlined to me, which makes them seem like the better choice for fast movement in the sky. You should consider using mythical creatures that are much more birdlike as your fast mounts... maybe something more like a hippogriff than a pegasus? Still not sure how to tuck those drag-increasing long legs away, though... horses just aren't made for flight!

I suspect the Quora question was specifically about the atmosphere of Titan. The thing about Titan is that yes, the density of the air is high, but the gravity is also much lower: about a seventh of that on Earth. Without significantly reducing gravity as well as increasing density it'll be tricky to get your mounted pegasi off the ground.

There are other problems with warm, thick atmospheres on low-gravity worlds (eg. everything blows off into space) but that's another question.

could a pegasus be light enough to fly and still strong enough to carry a person even in such an atmosphere?

Maybe. Clearly, human-powered flight exists in the real world, and humans and horses have pretty similar constraints on muscle density and power output. Throw in some avian adaptations to improve streamlining and reduce mass and you could just handwave things in as being plausible. I still think you'd need to reduce gravity a little, though... not necessarily as much as Titan, but down a bit from Earth-normal.

Passengers might need to be dressed in special streamlining gear, and use a special harness to stay attached.

Flying on something that is pegasus sized but shaped more like a bird than a horse is likely to work much better. A little simurg might be more suited to your needs. Could probably eat a pegasus, too.

  • $\begingroup$ What changes would the horse need to undergo in order to be more aerodynamic, but still have four legs and look like a horse? I was thinking about hollow bones, organs that store some light gas that helps in flight, folding your legs and lowering your head to reduce air resistance during flight... Because it's not a horse, but an animal that looks like one, I think it gives us a little more freedom to change the body to be more aerodynamic.So much so that I want my pegasus to whinny and have fur, but if need be, I think I'll have to sacrifice the fur and leave only feathers. $\endgroup$ Oct 1, 2021 at 12:56
  • $\begingroup$ @WizardKing birds are pretty pointy in a way that horses aren't. Its the head and face that are the next big things to consider after the legs... my suggestion of a hippogriff instead of a pegasus was basically driven by the fact that the front-end of a hippogriff is already known to be a flightworthy shape. I don't think fur is a problem (bats do ok, after all) but I don't know how horse-shaped you can get and still meet your requirements. $\endgroup$ Oct 1, 2021 at 13:06

Quadrupedal animals will need a redesign

To develop flight, it would be handy to be bipedal to start with, not quadrupedal. It was easy for some dinosaur species to develop flight.

Changes involved: the forelimbs are freed of carrying the weight of the animal, but need sufficient force to maintain flight, resulting in large muscles in the upper body. The center of gravity will move between the forelimbs, then a fleece or feathers can serve as means to fly.

A horse will be far more difficult: it is very quadrupedal. To adjust and still be recognizable as a horse, the horse would need to develop an extra pair of strong limbs on its back. Wings and possibly feathers would be only a small part of the redesign.


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