Flight?

[Ireth]

I have a question with regards to the vampires in my mythos. Many of them, especially the oldest ones, have been physically corrupted as a direct result of drinking human blood: this corruption manifests mainly by giving the vampires batlike wings, which grow out when the vampires are exposed to direct sunlight. The wings grow out from the vampires' shoulderblades, like in popular depictions of angels or demons, rather than the arms themselves morphing into wings. The older or more corrupt the vampires are (i.e. the more human blood they've drunk in their lifetime), the larger and stronger their wings are, to a certain point. Some of them have even achieved the power of sustained flight, and I'm interested in the biology of how this might work.

By looking at diagrams of bats and their wings, and then adjusting the measurements for a human, I've gathered that the ratio of person's height to wingspan should be roughly between 1:2.5 and 1:3, meaning that a vampire who's six feet tall would have a 15 to 18-foot wingspan at the state required for flight. Of course, then there are adjustments I need to make for differences in anatomy between bats and humans, mainly the lack of tails and thus the possible need for differences in location of parts of the membrane. Is there anything else, like body weight or bone mass that I should be thinking about as well?

 

[Steerpike]

Bats have skeletal adaptations that make them lighter, for flight, so there is less in terms of bone mass than you'd expect. They also have a ridge along the breastbone to anchor the the relatively large muscles needed to power the wings (this is something most birds have as well).

 

[Penpilot]

I know for birds they have hollow bones, and their anatomy is geared towards flying. Bird anatomy - Wikipedia, the free encyclopedia

You might be interested in this article. It says we can't fly like birds but there's scientific stuff you can use it to fudge facts, like wing span.
Why Can't Humans Fly Like Birds? | Wired Science | Wired.com

 

[Hans]

When making adjustions keep in mind these don't go linear with size. IIRC the needet size of wings goes quadratic, but could be worse.
Also there is lots of muscle mass needed, which humans just do not have. For realistic flight they would need a really huge chest. Or an other mechanism to move these wings and hold them up while gliding. I'd guess flying creatures of that size would be mainly gliders not flappers, like large or long range flying birds.

 

[gavintonks]

it is magic as leather wings are doubtful to support the carried weight so I would not be too concerned about the dynamic, and more the look and the nice idea of the wings becoming more daemon like, look at Henry Blake he has some amazing characters with bat wings

 

[Shockley]

Some notes on flight (which I have researched, actually):

Bats and birds use different flight methods. I'll explain how the bat operates, and you can extrapolate what the bird does from there. Bats are, evolutionarily speaking, descended from the same kind of thing that gave us gliding squirrels. So while they do fly, they kind of look like they're gliding for large portions of the process. But that's important: A bird has relatively weak limbs because of where they come from - in comparison, the bat arm/wing is extremely strong.

The bat wing is also more flexible than the bird wing, having twenty four joints. This means that they are able to hold their wings closer to their body at the end of the flap, cutting out a lot of the drag birds have and increasing the power of each flap. While birds can go higher (since they have the ability to lift off, which bats really don't) and further because of how high they can go, the way a bat flies is actually more efficient. If there were bats the size of eagles or hawks, they'd dominate aerial hunting.

Because of the way the wings are set up (using membranes as opposed to feathers for the bulk), the bat is also more maneuverable. They can make turns quicker than birds of equivalent size. It also makes them easier to injure/tear, but birds aren't exactly granite walls of imperviousness. This difference also makes a bat-bird difference extremely important: Bats don't have hollow bones and they don't have air sacs. They have relatively small bones, yes, but that only makes up for so much.

It's also important to look at the bat's tail. If the bat has a notable tail, it's attached to the patagium. This is to reduce drag and make it easier for the bats to just kind of ignore them. Tails are useful in some degree, but they're not necessary like they are in birds. One of the reasons some of the better planes used by the USAF (such as the B-2 Spirit) don't have tails or fuselages is because both of those things cause a whole lot of drag. The similarity between the way a bat looks and a B-2 are kind of obvious, if you have that in mind when you look at it.

If you're wanting to make these individuals capable of flight, well, batwings are the most realistic way to go about it simply because they are adapted for mammalian flight. Look at the similarities of the bat wing to the human arm just for proof of that:

To actually pull it off your vampires would need some absolutely insane arm/chest muscles, but there's no reason you couldn't do that during the transformation. Also, the wings would have to be several times wider than your vampires are tall.

As a last piece of information: I like the way that Terry Pratchett handles dragons. The larger dragons (he refers to them as draco nobilis) have wings, but they're vestigial. Smaller species of dragons do have wings and use them to fly, but he readily accepts that once you get to a certain size they would no longer function. So the draco nobilis flaps his wings and tries to steer with them, etc. but out of habit - he's actually lifted and propulsed (sic) by magic alone.

 

[Ireth]

Those are excellent points, Shockley. I'm specifically looking at bats as a model for my vampires' wings rather than birds. You're incorrect on one point though -- I stated in my original post that the vampires' wings grow from their shoulderblades, not as a transformation of their arms, so I imagine there would be different muscles needed for flight. To use your dragon example, a lot of the dragons you see in Western culture have six limbs: 2 forelegs, 2 hind legs, 2 wings. Same goes for my vampires, more or less. I suppose the wings could be counted as extra forelegs/arms, but the positioning is different than the actual arms.

 

[Penpilot]

FYI Here's some pics of the worlds largest species of bat. Giant golden-crowned flying fox - Wikipedia, the free encyclopedia I've been trying to figure if these were photo shopped, so take them with a grain.

 

[Shockley]

That's legit, Penpilot. They only weigh like three pounds, despite their size.

Ireth: Even if the limbs are attached to their back, they're going to hook into a lot of the chest muscles. Say they hook into the upper back, that's going to be the traps and the rhombus, possibly the infraspinatus. When those get used, they'll work the chest to some extent as well.

 

[expresiva]

They weren't necessarily photoshopped, however perspective is everything. The bat is much closer to the camera in both photos than it appears. These bats have 5 foot wing spans - not 12 foot wing spans, as the photo would indicate. I worked with them at a zoo when I was a zoo keeper for years - they are splendid creatures, but they are not the behemoths that these photos indicate.

 

[gavintonks]

I just remember that I read you need arm muscles as powerful as thigh muscles

 

[Anders Ämting]

They weren't necessarily photoshopped, however perspective is everything. The bat is much closer to the camera in both photos than it appears. These bats have 5 foot wing spans - not 12 foot wing spans, as the photo would indicate. I worked with them at a zoo when I was a zoo keeper for years - they are splendid creatures, but they are not the behemoths that these photos indicate.

Pretty much. They seem to be roughly the size of your average cat, and probably less massive.

 

[edd]

i am not really sure why you put so much thought into the wings because vampires in stories can turn to mist and change into wolves. day light so i take it that they don't die in day light?

 

[Ireth]

My vampires are very different than traditional vampires. They don't turn into wolves or mist; direct sunlight turns them into ugly bat-winged creatures if they drink human blood. Crosses and garlic don't harm them, but iron does.