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I'm creating a sub-race of extremely short and technologically advanced humans in my book. These humans, which are dubbed 'faeren' or 'faeries' have created backpacks that have insect wings attached to them, which allow them to hover or fly in the air. Could it be scientifically possible for a human 1-2 foot tall (30-60 cm tall) to be propelled by insect wings of 30 inches (70 cm) wingspan?

Edit: average weight is 31-38 pounds

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    $\begingroup$ Please read the tag description when you pick them. You had chosen two mutually exclusive tags. I have left the less stringent one. $\endgroup$
    – L.Dutch
    Commented Mar 12, 2023 at 18:50
  • $\begingroup$ Sort of a flying one-year old! $\endgroup$
    – Fattie
    Commented Mar 13, 2023 at 14:38
  • $\begingroup$ Note. Size is totally irrelevant in hovering / slow flight. All that matters is the weight. You should state the weight. $\endgroup$
    – Fattie
    Commented Mar 13, 2023 at 14:40
  • $\begingroup$ note if they are proportioned like humans they will freeze to death fairly quickly. $\endgroup$
    – John
    Commented Mar 13, 2023 at 22:38

2 Answers 2

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At a Stretch

Let's low-ball a $6$ ft person as weighing $64$ kilos. To turn the person into a fairy, simply keep the proportions and divide the height by four. The new height is $6/4=1.5$ foot. The new weight is $64/4^3 = 1$ kilo. Can a $1$ kilo animal fly on $30$ cm wings?


Edit: The question is asking for 30 inch WINGSPAN. Not $30$ cm WING LENGTH. Fortunately it is about the same. If the chest of a $6$ ft man is $12$ inches wide, then the fairy has a chest of $3$ inches or $7.5$ cm. So a $30$ inch or $70$ cm wingspan has $32$ cm long wings.


Compare to real animals. We look at falcons since they have short wings for their size. Falcons are built for maneuverability, not for soaring. According to everyone's favourite encyclopedia, the dimensions of everyone's favourite falcon are as follows:

enter image description here

The bird is $1$-$2$ foot long. It weighs up to $1.5$ kg and has wings $25$-$40$ cm long. Sounds like a $1$ kg bird could fly on $30$ cm wings. Or a $1$ kg person even.

There are other problems to overcome. For example making the person streamlined and using insect wings instead of bird wings. What I can tell you is the numbers you have chosen are in the right area.

Edit: Also note we have scaled down the person but not changed the materials. You might shave off a few more ounces by making the bones hollow or removing some organs. Hopefully this will not make the fairy shatter every time it touches the ground.

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    $\begingroup$ Fantastic. This is why we didn't want the green checkmark to show up too early. This has great information. +1 $\endgroup$
    – JBH
    Commented Mar 12, 2023 at 22:39
  • $\begingroup$ The 25-40cm in the referenced article is the chord measurement, not the span as the OP was asking. It does also provide a lower limit of wingspan as 29 inches, however this would likely be for relatively small and light individuals, and not for the 1kg weight that was calculated. $\endgroup$ Commented Mar 13, 2023 at 3:09
  • $\begingroup$ @ThatCoolCoder: I am curious, do you happen to know the wing span (and other related data) for the falcon? Can they be calculated from the wing chord? $\endgroup$
    – virolino
    Commented Mar 13, 2023 at 7:48
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    $\begingroup$ @Fattie I am not convinced. $\endgroup$
    – Daron
    Commented Mar 13, 2023 at 14:47
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    $\begingroup$ @Fattie Babies are much stockier proportionally to an adult. And they have big baby heads. I am talking about perfectly-proportioned scaled down people. They look a bit like these yokes: google.com/… $\endgroup$
    – Daron
    Commented Mar 13, 2023 at 14:54
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Humans have been having fun with jet packs (or, at least, the idea of jet packs) since a patent for the idea was filed by Alexander Andreev in 1919. A pack that has mechanical wings rather than jet fuel is really just semantics given your "technologically advanced humans." Rather than rocket fuel, the pack has a very dense "energy source" (aka, a battery, whether it's a "fuel cell" or something else) that operates motors and actuators at, IMO, the speed necessary to be like hummingbirds. After that it's all about material science to develop gossamer wings with the strength and weight characteristics necessary to lift a human.

So, Yup, scientifically plausible.

When it comes to the description in your world, where you'll have a challenge is explaining stabilization. Hummingbirds use the lower part of their body (not just the tail) along with a tail that can be spread out to different widths, rotated, and pivoted. Think of it as "scooping" or pushing against the air around the hummingbird to stabilize it's motion — or lack of motion. I don't know enough about the physiology of flies to comment, but I suspect a fly will be rotating the wings to achieve a similar affect. Rationalizing the stabilization might be harder than rationalizing the wings.

BTW, proof of concept is the helicopter backpack, which uses an electrical source (battery...) and the helicopter equivalent of your wings and deals with stabilization in a manner that's more like what I imagine for a fly. Yup, your wings are scientifically plausible.

Finally, I've ignored the question, "why would you want to do that?" Sometimes we build worlds because it's just too cool to not do it. There are a lot of problems with an insect-wing-style backpack, not the least of which is that wind of almost any strength would be incredibly dangerous. Not just in terms of being pushed into trees or against mountains, but in terms of being pushed into power lines or pushed so far that there's not enough power to get you out of the situation. Wind shear would be incredibly dangerous. Rain, snow, hail (oh... hail), all very dangerous. In other words, there's a real issue of practicality that comes with the idea. But... So honking what? The idea is cool! So go use your wings and remember that is a two-edged sword, because along with the technology to build the wings comes the scientific reasons why a society would never build the wings beyond as a hobby.

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    $\begingroup$ As much as I enjoy receiving that coveted green check mark, we recommend not awarding it for 24-48 hours. We have an amazing group of users all around the world and human nature is to basically not post answers to a question that's already been "solved." You might miss out on some really valuable information. $\endgroup$
    – JBH
    Commented Mar 12, 2023 at 19:10
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    $\begingroup$ ok yeah my mistake $\endgroup$ Commented Mar 12, 2023 at 19:24

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