Near-future weapons taking designs similar to 17th century weapons

Question

I am doing an alternate-history of Earth going into the science-fiction area. The split came with a portal to a new planet appearing around the 17th century. The portal deposited those brave enough to venture into it on the only continent on a new planet, roughly the size of the moon, with 25% earth gravity, and similar atmospheric makeup and atmospheric pressure.

The nation is having a technological revolution, putting them ahead of current-Earth, but tensions are also rising. What are some weapons derived from the 17th-century ones, that would fit a near-future setting?

Answer 1

If your 17th century cast-aways departed this realm before the Isaac Newton published his seminal works, then they could have developed their science on very different ideas.

A low-g world, recoil of firearms would be a more significant problem. The moment of inertia of the human form firing a weapon lets us sight down our extended arms. In a low-g environment, we’d either have to lower the weapon from our shoulder height or significantly widen our stance to maintain stability. One choice reduces accuracy, and the other is uncomfortable — standing upright with ones legs maybe twice shoulder width (as an extreme example for illustration purposes). So we might have developed rocketry into their weapons. The lower gravity means the ballistic arc is flatter and would be easier to judge by eye. Plus no recoil.

And without Isaac Newton poisoning their minds, they’d still embraced the Aristotelean model when they left. This would have given them warped understandings of the universe, and may be led them to surprising developments.

For instance, they still would have thought that the mechanical notion of impetus was a real thing. In searching to understand it, they might have unlocked deeper secrets of fundamental universal forces. They might have cross bows that fired pure force bolts — no mass so no recoil.

And, personal swords like foils and epee, being manifestations of honor and adulthood are still preferred. But, they might be electrified or incorporate atomic force vibrations, or both, letting them slice through metal or deliver lethal discharges.

The steel cuirasses worn by men-at-arms might be composed of pure force — to protect them against vibro-foils and vibro-epee — and can now stand up to modern non-alternate world rifle fire, because they never believed in those pesky Newton’s Laws of Motion.

Answer 2

Well after 400 years weapon designs change, look at our current weapons compared to then. You could keep in some aesthetic properties with the design but 17th century swords won't translate to 21st century drones.

The Gravity on the other hand does provide an important factor. Our tanks for example are weaker then they have to be and it is for a good reason, giving a tank to much armor/guns would cripple them in terms of speed, maneuverability and fuel consumption.

Alt earth on the other hand suffers less from this drawback. So in comparison their weaponry would be bigger and better armored but also a lot slower and easier to hit.

Answer 3

After a prolonged period of time, your explorers in .25g are going to have a difference in physiology from their forefathers. A good example of this is shown in "The Expanse".

This will inevitably impact weapon design. High recoil weapons will likely remain in the purvue of specialists. The reasoning is that with less gravity, there is no longer the need for high density bones. That means the skeletal structure of the mass of people would be risking breaking bones or shoulder dislocations with a high power rifle rather just a mild bruise from something larger than a .308 Winchester round. Even Muzzleloaders could have a substantial kick. So lets look at other weapons from the 17th century.

The Longbow might still be in use, but it won't be as strong as the Earth Prime version. The lethality would come more from better arrowheads. The Reasoning is that with the weakening of the skeletal structure, the higher draw weights simply won't be possible.

Crossbows could also work because they rely on mechanical advantage mechanisms to cock like a goat leg lever or a windlass so the strain is not on the skeleton and muscles to maintain draw.

Slender, very sharp personal weapons like foils and rapiers or long slender daggers are going to be likely for most residents of the low G world. They rely on precision and a sharp edge to do damage rather than momentum.

Body Armor is going to change radically. Heavy Plate is just too heavy to carry. Silks and synthetics are going to be focused on. Stuff to stop the cutting edge, so to speak.

Of course on earth we continued to develop chemically powered weapons, mostly in ways to improve loading and rate of fire as well as rifling, but the core of the firearm, a tube that uses an explosion to throw something out of a long tube. On the low gravity earth, you are going to see more experimentation with rockets and bombs. Triggers, Proximity sensors, guidance, and shrapnel. Maybe even rockets as delivery systems for Poisons. I think these will develop faster than Earth Prime, because Firearms are such an effective method for killing.

I'm guessing you will have to account for some things like this