Science Fiction Problems: Hovercrafts
Posted by erikthereddest
Hello everyone, and welcome to another science fiction problems! Sorry about being so late in posting this! This week will be focusing on a bit of a doozy, and since Brian has asked for a break this week, I’ll be posting both today and tomorrow. What could I be talking about that could possibly merit a 2-day posting streak? Why, hovercrafts, of course!
The Problem of Hovercrafts
Someone, somewhere decided early on in sci-fi that the wheel is way to primitive to exist
in the future. Cars and other vehicles must either fly or at least hover off the ground in order for them to reasonably fit in a futuristic setting, this person reasoned, and apparently most people agreed with him. From this we got Landspeeders and the Jetsons, and any number of other inexplicable flying car-things, and no one seems to care that the darn things don’t make any sense at all. Hovercrafts thus go right along with robots and lasers and rocket ships as far as the oldschool near-clichés go, and you can find them almost everywhere.
I remember being really excited as a kid when I discovered that someone had actually invented a hovercraft. I imagined a Back to the Future-style hoverboard that you could jump on and ride across the surface of the public pool to impress your friends. What I got was that thing (image left). Don’t get me wrong, there are a lot of great things about our current hovercrafts, but there’s a huge divide between what we see used today and what people put in their fiction. What people seem to want from their hovercrafts is a sort of half-plane, half-car vehicle that is capable of gliding from anywhere from a few inches off the ground to a few hundred feet (depending on the story), without friction, and apparently without the need for wings or other ways of gaining lift from moving air as in the traditional airplane. Is this realistic? Even possible? Well, I’ll get to that, but first, let’s take a look at our current generation’s best go at a hovercraft.
The Only Military Vehicle Manly Enough to Wear a Skirt
Yes, that’s what that black rubber thing is called. I’ll explain in a bit. The hovercraft (or at least the basic idea for it) was actually invented back in 1716 by a Swedish designer named Emanuel Swedenborg, but that design wasn’t motorized and relied on manual rowing. Skip to today, and we’ve put aircraft engines on the thing, and it works a lot better. Hovercrafts (or Air Cushion Vehicles, as they are more properly called) work by pushing air under the vehicle, creating a pocket of compressed air that is constantly venting out under the vehicle. The effect is a lot like an air hockey table, letting it slide over terrain or water almost frictionlessly.
The trick comes when the water or terrain isn’t exactly smooth, which is where the “skirt” comes in. By making the underside edge of the vehicle flexible, the hovercraft can “climb” over short obstacles, maintaining its air pocket and the lift it needs to operate. So, unlike the futuristic hovercrafts imagined in our science fiction, our current-day hovercrafts are not really “hovering” at all. They are in partial contact with the ground through their skirts, because otherwise there would be nothing to contain the pocket of air they ride on, hence the more accurate term “Air Cushion Vehicle” or ACV. Because of the way hovercrafts are designed, there are several advantages, as well as disadvantages:
- Almost-All-Terrain– doing what “duck boats” and other so-called amphibious vehicles only wish they could, hovercrafts work just about as well on land as they do on water, and transition easily between them. As assault landing craft, for instance, hovercrafts can be used to drive straight from the ocean right up onto land, and keep going, striking much faster inland than any other craft could.
- Mobility– because they’re riding on air, hovercrafts can gain speeds much faster than most standard boat designs, and since they are not actually coming into direct contact with the water, they are not affected as much by currents. Additionally, hovercrafts are capable of omni-directional movement, being able to turn and glide in any direction.
- Efficiency– because hovercrafts are riding on a cushion of air, hovercrafts can be designed to handle enormous loads in many situations that standard barges and vehicles could not handle. In water they are about on par with other ships, but have the distinct advantage of being able to come onto land, and can operate in very shallow water and swamps.
- Durability– In order for hovercrafts to be able to handle rough terrain, they need to have that flexible skirt. If the skirt is destroyed, the vehicle is completely inoperable on land, and crippled in the water. The design also requires large, external engines that can be easily disabled as well, which would also disable a hovercraft.
- Almost-All-Terrain– Yes, I realize this was in the Pros section. This is a sticking point for hovercrafts, because it does not specialize in a particular terrain, within many situations, a traditional vehicle far outperforms it. Hydrofoils and some other similar designs of boats can achieve higher, more stable speeds in water, although they are not capable of operating on land, and tracked vehicles like tanks can tackle rough terrain that would easily hang up a hovercraft. Even some relatively simple obstacles can completely disable a hovercraft, like a significant gap in the road, or a small trench, would completely destroy the air pocket under the vehicle.
- Overspecialization While Overly Generalized– Hovercrafts are both near-universally viable and practically limited. They can handle many terrain types, but not necessarily well enough for a given mission. They are fast, but vulnerable, and thus not ideal for most combat situations other than the insertion of troops on a beach. This is one of the biggest reason why we don’t see more hovercrafts- the biggest spenders would naturally be the military, but most of the time they can’t figure out a way to use them, and so they pull funding.
So, some neat advantages, but some pretty devastating faults to overcome. This is why Science Fiction writers have almost universally shifted to the Star Wars land-speeder type of hovercraft- we really like the idea, but our current tech leaves us with some really disheartening disadvantages. Never fear! Tomorrow’s post will be devoted to giving you some ways to make a hovercraft actually hover in some really cool ways that are actually based on other emerging technologies!
Until then, where have you seen hovercrafts in sci-fi? Seen any that struck you as particularly silly? Let me know in the comments below!