IEEE Future Directions
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Vacuum-tube transport
Vactrain, sometimes referred to as the fifth transportation means, is a transportation system based on pipes in which modular vehicles can move at very high speed thanks to a frictionless environment since the pipes themselves have no air -vacuum- and the vehicles don’t touch the pipe floating in a magnetic field (watch the clip).
In theory, one only need the power to accelerate the vehicle at the desired speed and then it will keep moving encountering no resistance. This would make for a very cheap transportation means.
Unfortunately, the cost of the infrastructure is exceedingly high, with present day technologies.
Hyperloop, being tested in the US and France in scaled down version, and targeted to provide services connecting Abu Dhabi and Dubai in the next decade is an example.
A Chinese company, China Aerospace Science and Industry Corporation, is also at work designing a Vactrain to run at commercial speed of 2,500 km per hour, after having proposed a concept for a flying-train at 4,000 km per hour that was received with some skepticism. That would make connection between Europe and China possible in 3 hours!
This is what the foresight team at the Imperial College envisage for the future of transportation, a world wide vactrain service connecting the globe beyond 2040.
There are several technological issues to be solved, like not interfering with the magnetic field at the various inlets and outlets (the point where the vehicles ae joining and leaving the infrastructure) and guarantee the integrity of the infrastructure, taking into account natural and exceptional situations (just think, as an example, the earthquake risk in California, rendering the planned San Francisco to Los Angeles route very challenging).
However, the most difficult issues are related to the cost of the infrastructure and therefore its affordability. The cost for the magnet required to ensure the levitation of the vehicle are astronomical, if we think of thousands of kilometres of pipes, and the power required to create the magnetic field along the pipes is staggering.
The likely solution for this latter should come from superconductive materials, but again their cost of operation today is way to high (these materials have to operate at very low temperatures, and maintaining these temperature is very costly).
We are likely to see a few vactrains in operation in the second part of the next decade, like in AUE and China, but their usage will be constrained by the high cost. They will be more like trials and evidence of what could become possible in the future.
It is obvious that a pervasive availability of vactrains would revolutionise the world of transportation and along with it our idea of the world. Commuting time between San Francisco and Los Angeles will be less than half an hour, likewise between Frankfurt and London. And if you need to span longer distances you can take faster vactrain, potentially travelling at 8,000 km per hour, getting from NY to Los Angeles in less than an hour.
Scramjets
Supersonic Combustion Ramjets is a technology, already proved by NASA, making use of the air compressed by a fast moving aircraft to generate trust. Engines using air compressed by the movement of the aircraft are called “ramjets”. The problem with ramjets is that the compressed air needs to be slowed down, to subsonic speed, in order to be usable in the engine. This slowing down creates waves that basically constrain the maximum speed of the incoming air to somewhere around 5,000 km. Above that speed it is no longer possible to slow down to subsonic speed the air in the engine and thrust is no longer created.
Using a different type of engine it becomes possible to use supersonic speed in the combustion camera of the engine (hence the name “supersonic combustion”).
These engines need air to work, so they are usable only in the atmosphere (not like a rocket that does not need air -it needs fuel and oxygen and it has to carry it all along…).
Potentially they should support very high speed in the upper part of the atmosphere, a region have little air and so little drag, thus resulting in more efficient flights.
Technology has still a long way to evolve to the point of making scramjets viable for a broad use, so targeting 2040 seems reasonable.
