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Assuming a constant drag coefficient, drag will vary as the square of velocity.Thus, the resultant power needed to overcome this drag will vary as the cube of velocity.
if its too fast it may give people heart attacks
High speed rail is already being used in many places around the world, except in the USA.
Perhaps the future is a maglev rail in a vacuum, but that may be dangerous as traumatic decompression could be lethal.
And, of course, the infrastructure to build it would be extreme.
The British have already put rail under the ocean... well the channel, and I can imagine a Gibraltar-Spain tunnel or bridge will come in the future. An underwater Atlantic or Pacific crossing is possible, but would be expensive, and would require some pretty extreme engineering to deal with pressures and safety margins.
QuoteAnd, of course, the infrastructure to build it would be extreme.Narrow tubes for narrow capsules (no room for passengers who are highly overweight) shouldn't be a great challenge. Aeroplanes are more extreme.
Quote from: David Cooper on 30/11/2014 18:58:23QuoteAnd, of course, the infrastructure to build it would be extreme.Narrow tubes for narrow capsules (no room for passengers who are highly overweight) shouldn't be a great challenge. Aeroplanes are more extreme.This statement is baffling. What infrastructure?
The beauty of air travel is that all you need is a bit of flat grass (though concrete is nice) at each end and nothing but air in between. No problem of demolishing houses or destroying communities to connect a thousand destinations in any order: you take off, then fly in a great circle direct to wherever you are going. GPS, radio and radar are useful but the capital investment is negligible compared with railways and the flexibility of air travel is unbeatable. I recently flew from Cambridge to Swansea for a routine job, but literally as I got out of the plane I got a call to an emergency in Dublin. No new infrastructure, no need to re-route anyone else or wait for tomorrow's train - just get back in the plane and fly direct across the water.
I can see why you find it baffling, but I wasn't talking about the infrastructure when I said aeroplanes are more extreme. What's extreme about planes is that you have to tie yourself into a bomb and blast through lots of thick atmosphere before you get to altitude, and even there you've got masses of air to punch through, so the pollution involved is astronomical.
If everyone on the planet flew about the way that you do, the pollution would lead to a collapse of ecosystems all by itself, and then the mass-starvation of billions.
That is where the future will inevitably take us, so it's a pity we have to watch so much of the planet being destroyed while the idiots at the top in politics insist on trying everything else first.
Planes also enable people to make lots of unnecessary trips that they simply wouldn't do by car, so the pollution goes up an up.
It's also better to go and live for a few years in a far-off country instead of flying out there repeatedly for short holidays.
Quote from: David Cooper on 04/12/2014 17:26:58It's also better to go and live for a few years in a far-off country instead of flying out there repeatedly for short holidays.But if you lived there, it wouldn't be "far-off", nor a holiday. The essence of holidays is their transience.
Are we going to be forever stuck in this air speed? What are the constraints of aerodynamics? Are noise rules the issue? Can a supersonic jet be ever built with "decent" fuel economy? Will we ever see another "Concorde" in our lifetime?
Throughout the 1950s an SST looked possible from a technical standpoint, but it was not clear if it could be made economically viable. Lift is generated using different means at supersonic speeds, and these methods are considerably less efficient than subsonic methods, with approximately one-half the lift-to-drag ratio. This implies that for any given required amount of lift, the aircraft will have to supply about twice the thrust, leading to considerably greater fuel use. This effect is pronounced at speeds close to the speed of sound, as the aircraft is using twice the thrust to travel at about the same speed. The relative effect is reduced as the aircraft accelerates to higher speeds. Offsetting this increase in fuel use was the potential to greatly increase sortie rates of the aircraft, at least on medium and long-range flights where the aircraft spends a considerable amount of time in cruise. SST designs flying at least three times as fast as existing subsonic transports were possible, and would thus be able to replace as many as three planes in service, and thereby lower costs in terms of manpower and maintenance....The desire for a second-generation supersonic aircraft has remained within some elements of the aviation industry, and several concepts emerged quickly following the retirement of Concorde....etc.