Dragon scales are foamy inside, how to make them more bullet-resistant?

Question

The three most common properties of dragon scales are:

• being lightweight
• heat-resistance
• just plain resistance

The first two are simple: by making the scales out of a substance similar to nacre, and by making that substance into a foam, dragons could effectively resist any change in temperature, and if they do need to warm up/cool down, they can just open their wings.

Plain physical resistance is harder, especially in a fantasy world with self-replicating Anti-materiel rifles and a pretty much extinct ATF.

So, the key problem with bullets is that they go way faster than any muscle-powered weapon, which ultimately allows them to ignore the cohesion of the armor even more.

Now, since the scales are much thicker than regular but only because they're mostly air. How can I make them more bullet resistant? And so, of the pool of natural bullet-resistant materials, does this limitation make one particular solution stand out as the best?

What's the best?

1. RHA equivalence, the higher the better (basically defensive value).
2. Density, the lower, the better.

Note: Of course, dragons could always resort to cheesy tactics, such as sticking shed scales back on themselves, if they ever needed to.

Answer 1

The dragon scale armor that the military used to use worked because its surface broke down into sand and flakes dissipating the energy of the bullet. then a new surface was effectively presented to the bullet and the process repeated.

While the Army stopped using that armor and the company went out of business, it was because of manufacturing problems producing the armor at the price point the Army would pay for it, and not because the approach was wrong.

Similarly, some WW2 tanks used a similar material and had incredibly durable armor.

So if your dragons scales shattered millimeter by millimeter as the bullet tried to penetrate them, then the bullet's energy could be dissipated without injury. Repetitive shots to the same spot will eventually penetrate.

Also, having angled surfaces increases the likelihood that a bullet will ricochet and not penetrate.

And, the sol-gel idea @AzureMinotaur put forward would complement this approach.

Answer 2

Some ideas:

1. Maybe incorporate a non-newtonian fluid that thickens under stress and can stop/slow down bullets. The dragon could even anticipate firing and pre-solidify the liquid by vibrating its skin underneath the armor. Maybe the liquid does not need to be present everywhere, but pumped wherever necessary, like blood, making more of a directional armor against bullets. This design keeps the overall density low.
2. Not sure what bullets in this world are made of, but in case they are electrically conductive, the dragon could produce a strong magnetic field significantly slowing/ deflecting bullets. A reason for this could be simply that the world has lots of this material easily available to make bullets from for the self-replicating rifles compared to other materials or the process of self-replication is more efficient when such materials are used for some reason.

A hybrid of (1), (2) could also be used by the dragon among other techniques. So it could deflect bullets just enough to direct them to the pockets of its armor where it has solidified non-newtonian fluid available for protection. The combination would make the amount of fluid needed even less, keeping density lower while increasing coverage of protection. To make it more interesting, if the fluid itself also reacts under magnetic field, the dragon could use the em field to move it around (instead of mechanically pumping it around)

Answer 3

Sand bags.

The scales are not bullet resistant. But the dragons can use them to create ad hoc bullet resistance. The dragon erects its scales as it rolls in the sand, then closes them down, trapping layers of sand between the scales. Maybe it gets wet first, or has tar or some other gooey material it preps the scales with. Or maybe after getting sandy it gives itself a light toasting, fusing the sand into place.

The result is a dragon wearing sandbag armor. Just as with a regular sandbag, shattering and friction of the sand grains absorbs the energy of the bullet.

A dragon wearing a sandbag would be considerably heavier. Large dragons might not be able to fly. Small dragons would sacrifice maneuverability.

When the time for fighting people with guns is done, the dragon will go swimming or shake vigorously to rid itself of sand.

Answer 4

Graphene is one of the strongest substances per weight known to man, due to its strong Carbon, carbon bonds.

It has a strength of 130 billion pascal, 500x the strength of a29 steel (400 million) or kevlar (345 million). It also is lighter.

So if your dragons scales were made out of it, they writings be evenly durable, light weight and far more bullet resistant forc the same volume.

Answer 5

The scales don't grow like normal scales, or even like feathers. They are extruded like spider silk, and knitted into your complex foam structure (which maybe isn't some random foam, but more like a 3 dimensional honeycomb sort of thing?) out of multiple different materials. They are relatively thin, overlapping heavily, more like feathers than scales, but still looking more scaly as they're single continuous pieces rather than branching structures. They are ablative armor. When they break they fall off and are replaced, quickly. Like you could say the armor is restored in hours.

You could also have these scales incorporate something like this: https://en.wikipedia.org/wiki/Dynamic_Armor.
(That would be one element where multiple materials would come in)

Your dragons would just want to make sure they don't get hit in the same spot over and over again.