What is an expedience of sci-fi gliders? these machines flying near the very ground

Question

What is an expedience of sci-fi gliders? these machines flying near the very ground.

It doesn't matter what they call them there (in different way).

No matter what specific principle they fly - what is the point as a principle? In all these fantasy worlds ... Why don't they rise higher as normal flying devices, why do they parody cars? Or this is it for those who are only afraid of heights or do not know how to fly vehicles in the air? Well, all these computers would handle it... If it’s about energy, i don't suppose that much less is consumed energy in this way. It's about building any sci-fi world, civilization and the technology that has such machines.

What is the meaning and purpose of this particular type of machine?

Answer 1

This sort of vehicle will become popular when

a) you get a repulsive principle which gets weaker with distance,

b) the repulsive force requires more power for greater force, and

c) the available power you can put in a vehicle is limited to a value which only produces a foot or two of clearance.

This produces a vehicle which will travel on any reasonably smooth terrain, and a sufficiently sophisticated repulsion control may permit operation on quite rough terrain: the repulsion can be reduced when the vehicle runs over a rock or bump, just enough to keep the altitude constant. Basically, it behaves like a hovercraft. It will be popular on "frontier" worlds where roadways are uncommon.

Presumably, military or police craft with expensive, high-power units can operate at greater altitude.

Answer 2

There are lots of possible reasons:

1. It's a hovercraft. Real-world examples: https://en.wikipedia.org/wiki/Hovercraft

2. It's an ekranoplan. Another real-world example: https://en.wikipedia.org/wiki/Lun-class_ekranoplan

3. It depends on a hand-waved anti-gravity repulsion effect, which drops as the square of the distance from the surface. No real-world examples, alas, but a maglev train is somewhat similar: https://en.wikipedia.org/wiki/Maglev

PS: Technology aside, there might be another reason, which is simply that it's fun. Ever looked out the window of a commercial airliner that's flying at a large fraction (typically 0.75-0.85) of the speed of sound? It seems like you're barely moving at all. Fly along with me in my single-engined prop plane when I've got the wheels down close to the sagebrush, and I guarantee it'll seem a lot faster. Likewise driving a sports car vs a jacked-up SUV at the same speed, riding a horse at the gallop, a sailboard in a good wind, and many other things. It's all about your point of view :-)

Answer 3

Why do you want a bridge when a taut rope would do?

It's al about safety. If I am traveling on a flying machine that is mass marketed for everyone like a car and which can ramdomly fail anywhere, I'd rather take a three feet fall than a three thousand feet one.

---

Also it'd be a hassle to climb up to the clouds when my final destination is the bakery just a few blocks away.

Answer 4

The vehicles are basically hovercrafts, sometimes with advanced sci fi technology making them work.

Hovercrafts are great for travel. Bumps in the road are no issue, you can float over obstacles, less friction so you can go faster. They aren't as expensive as aircraft, and they're less vulnerable to bad takeoffs than aircraft.

Irl, they aren't popular because they're fuel hogs, they're loud, and maintenance is difficult. In a sci fi future these issues could be overcome so they are the best method of transport, removing the need for dedicated roads.

Answer 5

To put it very simply - they can’t fly. Whatever keeps them from falling on the ground doesn’t allow them to rise thousands of feet into the air. Even worse, if they reach their max height limit and start falling, it’s unable to overcome the momentum of falling, so if you have a 50 foot ceiling and go over a 60 foot depression, you are probably going to crash. Go off a 100 foot cliff and it’s guaranteed.

Note that this actually in line with our real world equivalent’s. Real life vehicles that rely upon some sort of ground effect to stay off the ground, whether it is a hovercraft or an ekranoplan or a wig (Wing in Ground) or the Spruce Goose, if they “fly” off a large cliff and they will hit the ground at a terminal velocity..

If you look at the image you posted, it’s obviously not flying aerodynamically, and it’s not flying via kinetic repulsion. And it doesn’t have an airtight cockpit, so just looking at that, I would expect rising to 20k and flying to be impossible.

Answer 6

Technology limitations

1. They can't fly higher. The technology requires you to be somewhat close to a "solid" surface to work.

2. It isn't safe to fly higher. The technology used to keep it balanced requires you to be somewhat close to a "solid" surface to work.

3. You can't go as fast if you are higher. The technology to push yourself forward relies on being somewhat close to a "solid" surface to work.

Safety/regulation limitations

1. The technology itself is unreliable; unacceptably often it gives out, and the base of the vehicle is designed to survive a low-altitude crash.

2. The air space above the ground is reserved for other purposes, and being in it is a violation of the law.

3. The rules for a vehicle that can go more than a small distance above the ground make it too expensive to provide cheaply. So a limiter is installed to prevent the vehicle from becoming air-born, thus changing how the vehicle is regulated. These regulations could come from a safety, military, pilot license, or even random legacy legal crud place.

4. People shoot down flying vehicles depressingly often, and it isn't hard. On the ground you are harder to hit, and it doesn't matter as much.

Ignorance is Bliss

1. Nobody knows how the technology works. But you do X Y and Z, and you get something that floats a bit above the ground. The real reason may be anything above, but the people using it don't know what the real reason is.

2. There is a taboo about flying high in these vehicles. Nobody knows why you must follow the taboo, but doing so gets you in extreme social trouble.

3. It works perfectly fine, and when asked about it people are confused as if you are talking nonsense. When demonstrated, they express no surprise, but still don't understand when you ask them why they aren't doing it.

Answer 7

Why don't they rise higher as normal flying devices, why do they parody cars?

Very likely they work using a special field rather then simple reaction (momentum conservation) or pressure differential

Possible reasons that I can imagine, alone or in combination

• field strength decays much faster with the distance from the surface than increasing the available power of a mobile energy source can compensate
• the field produces side-effects in between the generator and the surface. The side effects intensity is acceptable in intensity for small distances, but become increasingly damaging (unsafe) at increased attitudes in respect with the soil surface. E.g. at 30cm, the field heats the air 20K above the ambient temperature, at 0.5m above the generate heat causes 100K temperature differential, at 1m the air underneath becomes a thermal plasma (you can write short stories based on the reckless behavior of race drivers boiling the spectators)
• the materials required to generate/sustain/orient the field have an inherent saturation intensity. Any attempt to go over a certain value will result in stray field lines escaping in unwanted direction causing instabilities in unpredictable/uncontrollable manner (like various types of instabilities keep the controlled nuclear fusion on a perpetual 30 years in the future).

Answer 8

They are simpler to use.

If you start flying high, at some point you'll need a jacket to keep warm, and a oxygen mask. Much simpler if you just fly near the ground where the temperature (and oxygen) is at normal levels.

Also when navigating by eye (assuming not every planet has GPS-like system) its much easier to have signs on the ground telling you how many miles it is to the next city. While navigation in the air would need more effort (and experience) by the pilot to be able to follow maps/dead reckon or the planet needs to invest in some sort of GPS-like system to be able to navigate. I know many people who still get lost with a GPS navigation device telling them where to go, which is much riskier if your stuck in the air rather than tuck near the ground.

Maybe there technology is unreliable (or people can only get hold of junk to build their vehicles from)? No one would fly in a plane that had a 50% chance of losing lift at any moment. But a land speeder that loses lift 50% of the time? Annoying but not life threatening.

There is also the consideration of whether a space government would want everyone to have what is effectively a small missile. A plane when crashing into a building can do a lot of damage, while a land speeder crashing maybe damages a building but not as much as a plane would.

Answer 9

I'm going to treat the hover part as simply a new form of wheels. As others have pointed out like a hovercraft it uses some form of ground effect rather than direct flight to stay aloft. This is also why such gliders can remain aloft even when the owners have effectively shut it down and leave it behind.

The reason why you would choose this over wheeled vehicles has simply to do with roads. Take any city or town and the most expensive and time-consuming project they had/have is their roadways. You have to spend days if not weeks checking and laying the soil layer by layer, then place the road support material and on top of that the roadway itself. These roads need to have a lot of standards to work. They need the right angle and permeability to get rid of rain, it needs to be the right mixture to reduce ice forming during the cold and not melt too much when its hot while also cheap enough to lay down the thousands of cubic meters of asphalt and ease with low cost to maintain that road.

Or you lay down some hard-packed earth and use a sci-fi glider instead. You cut down heavily on all the costs and the time spend on the roads while the vehicles are able to handle almost any surface as long as its reasonably flat (except water, hoverboards dont work on water).

Answer 10

You want to include a land speeder (as Star Wars calls them) in your world but can't think of a good justification? Unfortunately, that's a tall order.

Beyond the real-world practicality of special effects (especially pre-CGI), they appear in Star Wars because they capture the aesthetic feel that Lucus was going for back in the 70s. He wanted a world with fantastic technology that still felt worn-out and familiar. By presenting a basic, non-flying car he gave people something they were very familiar with. By removing the wheels, he gave them something of the fantastic. Honestly, it's probably one of the better tricks he pulled off back then.

After Star Wars, they reappear in various other fictional worlds mostly because they were in Star Wars. Just the association with one of the most recognizable media franchises in history gave them credibility. No one really asks the obvious questions (well, some do).

Is a "land speeder" viable in a new constructed world?

Sure, just don't explain it. As with every other movie, tv show, book, or other story that used them, the audience won't care. They're familiar and they're cool. That's all that matters.

If you want something better than "rule of cool", you have a problem. As demonstrated by the question, lots of "reasons" can be offered up but each one is easy to shoot down.

This is one of those that is either used without explanation or not used at all.

Answer 11

An "out of universe" explanation:

The readers/viewers know about cars as transportation vehicles that stay close to the ground and require sort-of level terrain.

This is clearly a car FROM THE FUTURE. Look: it even has no wheels but magically technologically stays afloat a fixed distance from the ground. Even though that technology is never explained.

Answer 12

Legislation and ease of operation

Flying vehicles require a skilled operator. You would also need a pilot's license/certification to be allowed to pilot them. For a ground vehicle you only need a driver's license and basic driving skills. Thus manufacturers artificially limit the maximum altitude to a meter or so to make it legally a ground vehicle. It also allows it to be operated easily - almost like a car. This also makes it cheaper as there's no need for a pressurized cabin, ice-proofing, radio for communication with air traffic control, etc. They are basically hull + power + engines. And since it's considered a ground vehicle, you pay significantly less taxes. Aircraft is considered a luxury and taxed heavily.

And the actual reason they are popular in science fiction is that they are obviously cool and futuristic, while a wheeled vehicle feels mundane and comparatively low-tech.

Answer 13

If you want a Star Wars specific answer, you'd be better off asking in something like the sci-fi SE (or researching repulsorlift).

But if you want a general justification, you can simply go with these two simple properties:

1. hovering higher off the ground requires more energy
2. increasing the mass (size of vehicle, number of passengers, amount of cargo, etc) requires more energy to hover at a given height

In other words, small vehicles close to the ground require less power. That means a simpler/cheaper/smaller source of power. It probably also means lower maintenance costs in terms of components and expertise.

Another thing to consider is that your power source is going to be split between lift and propulsion. For a given energy output, that means that being near the surface lets you go faster.

As also mentioned, there is a safety factor. It's less catastrophic for the vehicle to fail 1 meter above the ground than 1km above the ground. This might not be as relevant in very heavily populated areas where you have easy access to parts and repairmen with specialized skills and tools for regular maintenance, but in very remote areas, you might want something simpler that you can easily maintain yourself.

And before you ask for a mechanism of lift: it's made up. Star Wars, Star Trek, etc, all have their own fictional approaches to this. My answer is assuming that whatever made-up mechanism is being used has the property that hovering higher = more power required.

Answer 14

Another possible explanation: They can fly but it's inefficient. The higher you go the more energy the repulsor needs. Perhaps this is even prohibitive--try to fly too high for too long and you overheat the drive.

No current technology can produce such craft so the drive is inherently handwavium, make it work how you want. (Yes, the ekrantoplan has been mentioned--it has a minimum speed for flight that's not much below it's cruise speed. It doesn't behave anything like the craft pictured.)

Answer 15

Just to give the (obvious) psychological answer... Humans think about travel in two dimensions; travel is conceived over a surface, not through a volume. The reasons for this are subtle, and related to the reason why ancient humans thought of the sky as a flat bowl: we are far more attuned (with respect to long distance) to front/back/left/right than to up/down.

So, when people want to go from point A to point B, they think about it in terms of travel over a (more or less) flat surface, just as though they were going to walk the distance, except faster. A car, speeder, floater, or other just-over-the-ground vehicle fits into that expectation nicely.

I'll add, for interest's sake, that sticking close to the ground is likely more efficient in all cases. The alternatives — trying to achieve lift (like an airplane) or relying entirely on thrust (like a rocket) — mean that substantial energy must be consumed merely overcoming the object's tendency to fall like a rock. A vehicle that has a relatively passive mechanism for keeping itself slightly off the ground (ground effects, wheels and springs, hovercraft air pressure, anti-gravity, etc) saves a tremendous amount of energy, and achieves most of the advantages of true flight. Further, it avoids the need for centralized landing areas designed to accommodate the huge inertia of a jet landing (aka a controlled fall) or the heat energy released by a rocket pushing back against the earth's gravitation.