# Vehicle design

Most vehicles are simply a well-designed implementation of an internal combustion engine housed inside other mechanical systems:

1. An engine that powers the entire vehicle, typically gasoline or diesel.
2. For an internal combustion engine, an elaborate gear system that transfers the torque from the engine's flywheel to the axles.
3. An electrical system that operates a small electric "starter" motor from a battery to engage the engine, then an alternator on the "serpentine belt" that re-powers that battery, as well as any larger charging systems if it's a hybrid.
4. Impact protection for the vehicle and payload (i.e., cargo, operator), which often includes a spring-based or shock-based suspension assembly if it travels on land at all.
5. Various impact-triggered systems that safely protect the driver in the event of an accident (e.g., seatbelts, airbags).
6. A fully contained HVAC system that feeds heat from the engine or refrigerant-cooled air into the cabin at the user's selection.

## Railroads

A railroad is a pair of metal rails designed to guide a locomotive down an expected path. Historically, the engine was originally steam-powered, but they can often be electrical, and can also use gravity to generate its electricity. Depending on the pathway, it can be [self-sustaining](https://newatlas.com/transport/fortescue-wae-infinity-train-electric/).

At one time, the rails were bolted together, but they're now welded together to allow faster speeds. They therefore have to stress the track during installation to make sure it doesn't buckle from the stretching and contracting from the heat generated from the trains. Without rigorous stressing at higher temperatures, the rails will buckle and trains will derail, which causes *gigantic* spills of all the cargo.

The railway sleeper is a horizontal board that was historically wood, but can be made of stressed concrete, composite plastic, or steel. Its purpose is to distribute the load at even intervals onto the ground. To accommodate shifts from heat expansion and contraction as the engine travels over it, the sleepers are attached to the rails with clips or anchors.

Further, when laying track, the tracks must have track ballast between the sleepers and ground. Ballast are made of crushed, jagged stones. This permits the track to be raised (and therefore compensate for irregularities on the ground across a long distance) but also gives a cushion that bears the load of the train as it rolls across it. The rocks must be jagged for them to fit together (since they'd slide out under the pressure if they were smooth), and too much fouling (dirt getting in them) will fill the gaps in between the stones and eventually cause a derailment.

Generally, the gauge of the rails (distance between them) is set to be nearer (4'8.5") when carrying heavier loads, while the comparably lighter passenger rail needs a broader gauge (5'6") to prevent from winds blowing them over.

## Automotive

[Automobiles](autos.md) add even *more* to a standard vehicle's engineering requirements:

1. Composite materials in tires that engage from the axles to the road which can withstand tends of thousands of miles of a wide variety of terrains.
2. In newer autos, [computers](computers.md) that regulate an engine's timing and all the components, as well as often embedding a tablet computer into the dashboard, complete with internet connectivity.
3. If there are any autonomous features like self-parking, it also includes [advanced AI](computers-autos.md).

However, in some ways, electric vehicles are inferior technology to the standard ICE automotive:

- They remove the mechanical force applied by kinetic explosion in lieu of stored electrical energy, which means they have *far* less torque.
- Batteries have a much lower mass-to-energy ratio compared to gasoline, meaning their effective range is less, though that could change with improved battery technology.
- Charging batteries requires infrastructure (and the energy offsets to the power grid instead of being locally stored), and can take hours for a full recharge. However, swapping out batteries is often a viable option.
- Ecologically, batteries require rare-earth metals that are *very* volatile and destructive once expended, while refining and burning hydrocarbons only produces air pollution. It's the difference between more high-end landfills and simply planting more trees.

## Aircraft

The precise elements of getting aircraft to stay in the air are *very* particular, but the general idea is always roughly the same:

1. Air moves over a flat object that's curved on the top side.
2. The curved part slows air and lowers the pressure above it.
3. The flat object generates force that moves it toward the curved part.

The same principle applies in helicopters to the rotating blades, as well as airplane propeller blades.

However, there has been a recent development in aircraft: an aircraft can run more silently by generating a flow of ions aboard the craft and launching it behind it, creating enough thrust to fly the craft.