Resistance and Flight

Question

Well, I'll start by giving an introduction. In the past, some people were persecuted for possessing magic. Wherever they went, the profane (those who have no magic) found them and killed them, even on distant islands and dense forests. One day, tired of running away, but without offensive forces to fight back, a group of magicians (those who have magic) got together to create a world of their own and live in peace, took the magicians they managed to rescue there and founded a new one civilization where they managed to evolve more and more magic in an offensive way. With magic, created various magical weapons and war animals, one of these animals are dragons. In the present day, magicians decided to return to Earth declaring war on the profane seeking revenge for the past full of persecution and the profane will use the weapons of the present day in this war.

This species of dragon I mentioned has four limbs (two wings and two legs), a wingspan of 15 meters, is carnivorous and serves as a mount. Since the dragon will be used in a war against firearms, what would it take to make it more resistant against bullets?

Details:

• I'm avoiding solutions that aim to use magic and looking for logical solutions;
• The dragon does not need to be immune to bullets, but at least it would take several shots to be able to kill him instead of just one in the head or chest;
• How the dragon will be used as a mount can't be something that makes it too heavy since it won't fly with magic;
• It is not the type that spits fire, ice or produces poison. I don't understand much of this, but I suppose the lack of a system that produces fire or poison helps make the dragon lighter, even a little;
• Resistance has to come from biological processes and without having to use things found in the environment such as sand, stone or metal. Only if it comes from the dragon's body.

Answer 1

Natural Armor with Feather-like Substructure

Dragons not only have tough thick skin, their bodies are covered with incredibly tough light scales that layer over each other. These "scales" have a strength and hardness similar to kevlar, but they are mostly hollow with a remarkably strong and complex substructure like feathers making them incredibly light. (If this seems unlikely, remember that feathers evolved from scales)

The wings would not have to be covered with these scales because they would not necessarily be very vulnerable to bullets either as wings are big and bullets make tiny holes. Larger projectiles such as musket balls and Scorpion bolts can be discounted because unlike what you see in that ridiculous scene in Game of Thrones, hitting a far away flying target with a mechanical projectile weapon and/or a non-rifled musket ball is nigh-impossible.

If you were thinking of covering the dragon with manufactured armor to protect it, this is a bad idea in terms of aerodynamics and physical reality. Flying creatures are evolved to have a certain aerodynamic profile and to be able to carry a certain weight (prey) with that profile. Artificial armor is wholly impractical because:

1. Unlike naturally evolved armor, it would have to be heavy(*), seriously affecting the dragon's ability to fly and maneuver,
2. It would ruin the dragon's aerodynamic profile (much more so than a single rider), creating a lot of extra drag and possible weight shifting
3. It might constrain the dragon's limbs and movement making it difficult for it to fight with its feet, maneuver with its tail, or worse, its ability to flap its wings with power and simultaneously, precisely control their surface angles and contours.

Background:

On your world, dragons evolved from reptilian creatures similar to dinosaurs with a pteranodon-like body. Like some dinosaurs their scales were already evolved into proto-feathers (believed to originally be for controlling the retention of body heat).

However, unlike, say Archeopteryx this creature's proto-feathers did not evolve to enable flying (it could already fly), but rather they evolved to aid in defense without inhibiting its ability to fly. Thus while still feather-like they became broader, and flatter and tougher on one side, replacing/enhancing the keratin with a much harder version that was similar to kevlar.

(*-unless this civilization is more technologically advanced than we currently are, in which case fighter jets would make all dragons obsolete)

Answer 2

The dragons are aerial siphonophores.

https://c1.staticflickr.com/1/400/19724048832_e1a82de8be_b.jpg

https://en.wikipedia.org/wiki/Siphonophorae

Although a siphonophore may appear to be an individual organism, each specimen is in fact a colonial organism composed of medusoid and polypoid zooids that are morphologically and functionally specialized. Zooids are multicellular units that develop from a single fertilized egg and combine to create functional colonies able to reproduce, digest, float, maintain body positioning, and use jet propulsion to move.

The dragon is composed of several hundred thousand zooids. A bullet traversing the dragon will kill the zooids in its path; those zooids adjacent to the void close ranks to fill its space. A dragon does not offer much resistance to a bullet which will generally fly out the other side with most of its kinetic energy. Riders must use shielded saddles to avoid being struck from below.

A dragon which is shot hundreds of times will be smaller but still functional. If a dragon is cut in half by gunfire it will take longer for the halves to rejoin. If one half is lost the remaining half can reconstitute a smaller dragon with reallocations of remaining zooids.

The dragons are carnivorous, as siphonophores are. They prefer to feed in water full of small organisms in the manner of their ancestors and this is the environment they live in when not flying. They can eat the meat of land animals if it is broken down some and their handlers usually just put cut up carcasses in the pools where they live. The dragons eat the decaying meat but also smaller organisms drawn to the meat.

Siphonophore bonus: they glow.

Answer 3

There are several biological processes I can imagine that would render a dragon largely resistant to bullets.

1. Oobleck for body-fat.
2. A mesh of something like spider-silk under their skin
3. Hard secreted resins on their scales

The Oobleck would be a non-newtonian fluid which acts like ballistic-gel. Essentially just normal body-fat but a bit thicker.
The spider-silk mesh acts somewhat like kevlar and similarly distributes the kinetic energy of a bullet.

The resin would be a self-healing outer defence which catches blades and either splashes or shatters when impacted by a bullet.

A combination of all three might well make a dragon entirely proof against small-arms fire.

I imagine the resin being particularly fire-retardant as well.