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How Will We Get Around Near-Future Earth?
Slob Nerd points to this BBC article on future transport possibilities. It begins "The prospect of a revolution in air travel has been raised by Nasa's successful test of a 5,000mph plane. But are we likely to see similar advances in other forms of transport? Dusting off the crystal ball, what changes might come in the way we get around? What big ideas are out there, and do they have any chance of seeing the light of day?"
Planes need fuels like Kerosene and Diesel, that is, heavy hydrocarbons. Without such energy dense fuels they can't get off the ground.
That's just plain silly. First of all, they're not 'heavy' hydrocarbons. Many, if not most space launchers have used kerosene as a fuel, including the Saturn series of rockets. They use it because it's a particularly light fuel. Liquid Hydrogen + Liquid Oxygen is better, but requires a lot of cryogenic equipment and has only come into style in the past couple decades.
Planes, on the other hand, have much much much less restrictive fuel requirements because they get remarkable amounts of lift from the atmosphere, whereas a rocket has to brute-force its way up against gravity directly. Planes don't need any particular fuel at all to fly in many cases (See: gliders, hanggliders, etc) and if you want sustained flight, it's quite possible to pedal wherever you want to go (until you get tired, which'll be quickly!)
Admittedly, neither of those methods will get you anywhere fast, but the point is, that planes don't "need" this superpowered fuel any more than your car "has to have" gasoline. Well yes, it does, but only because it's so abundant at the moment that we don't have any motivation to look for something different.
There are all sorts of possibilities for building high-speed airplane without using fossil fuels. Hydrogen comes immediately to mind as nearly a drop-in replacement for the fuels in turbojet engines. It's already being used in the scramjet engine, you'll notice. But why stop there? Alternatives abound, consider a ground-based catapult launch system to get the plane up to a reasonable velocity, then just coast with some conventional prop engines until you arrive at the destination. Perhaps more research into the phenomenon that powers the high-voltage tinfoil lifters that kooks claim are anti-gravity machines will yield a new type of economical atmospheric propulsion?
Be a bit more creative. (And don't complain that these may be more expensive than current fuels: If we run out of fossil fuels, everything will be doubling in price and then some, so you'll get used to it.)
Random and weird software I've written.
I've heard the Free Flight theories... I know NASA's been pouring money into it.
It's a waste. As someone in the aviation industry, I'll tell you it's a crock and a waste of taxpayer and corporate R&D dollars, though it doesn't have to be. Light jets... does anyone KNOW what the cost of maintaining an aircraft, let alone a TURBINE aircraft is? You can't just get parts at AutoZone and let some yokel install them. And turbines ain't cheap!! A Cessna 172 burns about 9 gallons of fuel per hour (gph), or 54 pph. A light jet engine powering an aircraft that could carry a similar load would burn at least to 150-200pph. (20-25 gph, a figure quoted for a proposed jet using the Williams International FJX-2). Furthermore, that's at altitude-- tubines are very inefficient at altitudes below 29,000 feet. And if you're making small hops, you spend a lot of time dinking around below FL290.
Secondly, consider why the cost of general aviation has skyrocketed after September 11, 2001. Fuel doesn't cost much more, nor do aircraft, nor hangars nor landing fees. Insurance is the cause of the rise. And insurance for TURBINE aircraft is higher, much higher. Insurance for single-pilot turbine ops is insanely high, because turbine acft are both complex and very fast. Complexity and speed mean you can get behind the aircraft much, much more easily. Having an autopilot doesn't mean a thing, because what kills people now is getting behind on the damn button-pushing and forgetting to FLY the aircraft. Pilots spend too much time head-down, programming, and not paying attention to where they are and what the plane is doing.
I haven't heard ANYONE credible address how the insurance companies will treat a new generation of unproven light jets that fly random courses across the country, landing at small airports, and that are designed to be flown by ordinary owner-operators instead of professional pilots.
Third, where will we fly these things? We're currently revamping airspace above FL290 to increase the capacity of the system, and this requires a LOT of new (read: expensive) equipment for DRVSM. Oh, and one other thing: You can't just hop in a jet and fly away- you MUST have a type rating, and those generally cost about $10,000 and require more smarts than driving your Lexus to Starbucks for coffee. New transportation scheme? Only for the insanely rich. Free Flight is a lame duck in my book.