Would keratin, spider silk, and bone make good bio-engineered armour?

Question

So, setting is an extremely advanced race who use bioengineered tech in many applications, although most commonly in warfare. Their combat troops are large exoskeletal creatures ranging from hand sized spiders to horse sized scorpions. My idea was to have the exoskeleton composed of keratin, spider silk, and bone. It does not have to be in discreet layers as the tech is advanced enough to give the armour a complexed 3D structure. Most opponents are less advanced, in the case in question they stand at around human levels of tech. The armour is also grown into wearable plates as personal armour.

Question is this: how effective would the armour be? What would be its weak points, and strengths. What weapons would be most effective?

Note: I understand that any race this advanced will have better armour. However, the bioengineered 'soldiers' can be grown quickly from the resources on the planet they are invading. This is important as the story is meant to be 'hard sf' so interstellar travel is to difficult to carry a ready-built invasion force.

Answer 1

Spider silk is amazingly strong (something like 17 times more tensile strength than steel per unit weight), so the idea of making body armour out of silk isn't strange at all. The only difficulty is to scale up production to meet the requirements of a large scale force, and in our world genetic engineering is being used to do unlikely things like coding for spider silk proteins to be expressed in goats milk!

Keratin is the protein used for skin, nails and hair. Very strong materials can be made from this, but it isn't nearly as tough as some of the shells of various molluscs, which turn out to be a composite of ceramic like calcium compounds in a matrix of a more flexible protein, which provides strength without being brittle.

"Wet" bone in living creatures shares some of the same properties; bone under a microscope looks a bit like a sponge with calcium particles suspended in the matrix (yes there is a lot more to bone than that), but since the scale of the particles and the matrix is much larger than in shells, bone is actually not as strong or "tough". The need for bone to be "wet" (i.e. living tissue) in order to remain strong will also be an issue if you want to use it for armour.

Answer 2

Bone, silk and keratin are strong materials in their own right but I wouldn't use them for high value foot soldiers. As you said, there are better materials, use them for the elites.

Use these cheaper materials to make cannon fodder shock troops. For any kind of invasion, you need lots of them. Make zerglings or hormagaunts in the millions.

Ranged weapons take extra resources so just give the shock troops melee weapons. If enough of them survive to melee range, whatever weaponry the enemy has won't do them any good.

Answer 3

You should consider that while spider silk, keratin, and bone are each strong in different ways they did not evolve to function as armor. While this means that they may not be ideal as armor, it opens up the possibility that other organic materials that were designed to function as armor could be orders of magnitude more effective. If your aliens are sufficiently advanced I see no reason why they would be limited to using existing biological materials to make armor for their soldiers. They could engineer something far, far stronger. Imagine an armored skin composed of a single molecule of layered and interwoven spider silk filaments, or even carbon nanotubes. Engineered organic armor could be vastly stronger than any known material. Potentially any organic molecule you can think of could be synthesized by engineered enzymatic processes.

As to your question of what sort of weapons might be effective, it depends on the exact nature of the armor. If it is brittle and hard then kinetic weapons like bullets may be able to crack it if they can deliver enough force to a small enough point, but the armor will be resistant to shockwaves as it won't propagate the force to the interior. If the armor is elastic and flexible bullets will have difficulty penetrating, but the shockwave of hits and particularly explosions could still be transferred through the armor to cause internal damage. If the armor is well-made and layered to be both hard and elastic, well, you are just going to have to shoot them a lot. Or try fire! Organic things tend to burn and sufficient heat could break the molecular bonds holding the armor together. Also maybe very strong armor is not very good at allowing a creature to cool off. Cook them in their own super-armor oven.

Answer 4

Well according to this article they have made material from spider silk that can make bulletproof vests. Regular silk has been known to stop projectiles and be used as body armor. The mongols used it to protect against arrows. They've even recently proven that if Archduke Ferdinand had been wearing his vest, his assassination would have been stopped (gun shot!) and something else would have sparked WWI.

Now taking this bit of news and adding in keratin and bones to add some rigidity and strength to the armor, maybe even some sharp edges it seems like it could be very reasonable body armor. The big thing is cost of production vs. overall protection. If this can be 'grown' cheaply, then you have a pretty good idea here.