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Science Technology

How Will We Get Around Near-Future Earth? 974

Posted by timothy
from the cold-fusion-hybrid-flying-recumbent-bikes dept.
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?"
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How Will We Get Around Near-Future Earth?

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  • Required comment ... (Score:2, Informative)

    by i.r.id10t (595143) on Wednesday March 31, 2004 @12:41AM (#8722225)
    Required comment regarding my flying car, or lack thereof.
  • Magic 8 Ball (Score:2, Informative)

    by mazarin5 (309432) on Wednesday March 31, 2004 @12:43AM (#8722244) Journal
    I predict higher population density, growing urbanization and the increase of public transportation and pedestrians.
  • Re:In the future (Score:5, Informative)

    by ePhil_One (634771) on Wednesday March 31, 2004 @12:46AM (#8722274) Journal
    The earth will be paved. With concrete.

    Asphalt, not concrete. Concrete requires expansion joints, which can cause problems at 300+mph, even in hypercars. Read the FAQ.

  • Re:I dunno . . . (Score:3, Informative)

    by Gewis (717661) on Wednesday March 31, 2004 @12:56AM (#8722341)
    A fusion related accident isn't going to be bad. There is no melt down. If your field loses confinement, everything cools down nearly instantaneously, and you just have this hydrogen and helium gas sitting in your reactor. There are no control rods, no heavy isotopes... That's why it's so great: it's nearly perfect. It has potential to provide cheap energy, clean reactions, minimal hazards... Now, whether that will have anything to do with transporation is another question. Mr. Fusion isn't likely to see break-even on your hover-car.
  • GO Transit (Score:3, Informative)

    by Kenshin (43036) <kenshin&lunarworks,ca> on Wednesday March 31, 2004 @12:57AM (#8722351) Homepage
    The trains that come into the city only do during rush hour (which is good, but it'd be nice if it was at least 18 hours a day).

    What dark subway tunnel do you lurk in all day? The GO Trains [gotransit.com], brining people all around the 905 into the city, run from about 6am to 12:43am. I use them all the time...

  • Re:G Load (Score:2, Informative)

    by sashang (608223) on Wednesday March 31, 2004 @01:03AM (#8722398)
    it's the acceleration not the speed that determins the g force
  • by QuaZar666 (164830) on Wednesday March 31, 2004 @01:07AM (#8722428)
    I will give you the flying car under one condition.

    http://www.viewaskew.com/tv/leno/flyingcar.html

  • by a1cypher (619776) on Wednesday March 31, 2004 @01:13AM (#8722473) Homepage
    It seems to me that alot of people arent putting much thought into these Hydrogen powered car alternatives.

    Sure, their only biproduct is H2O, but the hydrogen has to come from somewhere. It takes quite a bit of power to get H2 via electrolysis of water. And all that power has to come from somewhere.

    Hydrogen powered cars wouldnt really be more environmentally friendly, it would just make the consumer believe it is by shifting the responsibility from the consumer to the company in charge of generating the H2.
  • Re:Transporters (Score:3, Informative)

    by ePhil_One (634771) on Wednesday March 31, 2004 @01:15AM (#8722488) Journal
    You can try to hide the Dulce Base [google.com] conspiracy all you want. Just tell me, are you working for the government or for the aliens?
  • Cars With AutoFollow (Score:3, Informative)

    by superid (46543) on Wednesday March 31, 2004 @01:20AM (#8722516) Homepage
    In the next 5 years we will see cars introduced with viable "autofollow" where a car will know it's relative position in traffic and be able to safely autopilot itself. Toyota is already demonstrating it here [msn.com]

  • by erice (13380) on Wednesday March 31, 2004 @01:25AM (#8722542) Homepage
    The problem is that we seldom build cities. Cities morph -- especially in our suburban mindset we've have for the past century or so

    Cities are not built house by house though. Most of the time, whole subdivisions are built more or less at once. Most are not walking and biking unfriendly by accident. They are designed that way.

    They *could* put in sidewalks, but chose not to. Commercial and retail *could* be included but are not. New subdivisions *could* be criss crossed with minor streets great for bicycling but instead every neighborhood street ends in a cul de sac and traffic is diverted to arterials.
  • Re:High speed trains (Score:5, Informative)

    by Ironica (124657) <pixel@NoSPAm.boondock.org> on Wednesday March 31, 2004 @01:28AM (#8722557) Journal
    It's a lot more economical than air travel, can be just as fast (with aiport wait times and all), and is just as if not safer than flying.

    Unfortunately, it's not necessarily more economical.

    Believe me, I much, much prefer rail to air. It's far more comfy, safer, and the view is better. But a study (done in 1996 by David Levinson) of the proposed California High Speed Rail system for the Los Angeles to San Francisco corridor found that the costs per trip, compared to air travel, will be about double. That includes externalized costs, such as fuel emissions and noise. The proposed HSR system would even be more expensive than driving.

    The good news is, a much, much higher ratio of the costs are internalized in those figures. That means that passengers would be bearing almost the full costs of their journey, unlike highway and air journeys where more costs are externalized.

    The numbers go like this:
    ..........Internal...External...Total
    Highway...135........21.........156
    Air.......77.5.......4.5........82
    HSR.......157.65.....1.35.......159

    That's in dollars per passenger. (I tried to make it legible. I'm afraid it's in /.'s hands now.)

    Now, Levinson [umn.edu] is very hung up on the enormous capital cost of building the system, so he is possibly incorporating debt maintenance into those cost figures. However, the location I'm citing (which is a PDF of a class lecture presentation) references "fuel costs," so that may be the only consideration. (That seems unlikely, though, since it costs a lot less than $135 to fill your tank twice for the drive up to the Bay Area.)
  • Light Rail (Score:3, Informative)

    by orion024 (694922) on Wednesday March 31, 2004 @01:30AM (#8722573)
    Here in Houston, the 4th largest city in the U.S., we JUST got our first light rail. Yes, our first. And sadly, additional funding for the program barely passed.

    The light rail opened the 1st of the year. So we are just coming to 3 months of service... and guess what? We've already had 31 accidents involving the light rail. That's one practically every 3 days... so sad, so very very sad. Apparently, people don't understand the concept of "don't stop on the tracks" and "don't turn in front of the train" here.

    Houston has some of the poorest public transportation I have ever seen. But, I have to admit, the light rail is a step in the right direction. Right now, I spend over 2 hours a day in my car... and this is for a commute of only 18miles each way. Hopefully, they will expand the light rail. Building and expanding more highways is _not_ a solution. Fortunately, the light rail seem to service a rather large volume, and has been well recieved. Too bad the expansions are going to take 10 years+ to complete.
  • by OgreChow (206018) on Wednesday March 31, 2004 @01:39AM (#8722626)
    I believe he is saying that cities should be built in such a way that bike travel or walking are facilitated. Ruling out modern automobile transport would obviously be foolish.
  • by Ironica (124657) <pixel@NoSPAm.boondock.org> on Wednesday March 31, 2004 @01:41AM (#8722639) Journal
    They require completely new airports - out of the question in most large cities, where the cities grew around the airport and there is no possibility of expansion.

    Apparently, LAX [lawa.org] can already handle the new Airbus A380 [airbus.com]... at least, to the same extent it can handle existing aircraft. (For years now, the space between the jetways has been inadequate for two planes to pull out side by side... they have to dovetail them carefully.)

    Where the problem really lies is not in the physical size of the runways and terminals, but the people-carrying capacity of the big hub airports. They already run most of them on a pulse system, where all the flights come in at the same time to make transfers easier. This means you're handling all your traffic at once, and have to hire enough people, open enough gates, etc. to handle all those passengers simultaneously (while those employees sit around with pretty much nothing to do for hours at a time between pulses). By increasing the number of people that can arrive on each plane, you stress the baggage claim, security checkpoints, vendors, etc. *inside* the airport a great deal.

    But for an airport like LAX, this isn't an issue. Flights are constantly arriving and departing, and 86% of the passenger traffic is beginning or ending their journey... very little transfer traffic, so not much pulsing. They're not overly concerned about the A380s. I think the Department of Transportation is more worried about the added street traffic they might generate.
  • by Moofie (22272) <lee.ringofsaturn@com> on Wednesday March 31, 2004 @01:42AM (#8722649) Homepage
    How big do you want 'em? [airbus.com]

    Actually, there is a strong movement towards smaller, more efficient jets to supplement the hub and spoke airliner infrastructure here in America. But the new Airbus A380 is going to be as big as anybody (who doesn't want to build new airports) is likely to need in the next several years.
  • Re:I dunno . . . (Score:3, Informative)

    by petabyte (238821) on Wednesday March 31, 2004 @01:43AM (#8722657)
    When the containment fails in a fusion reactor, the pressure on the plasma drops and you generally end up with a chamber of radioactive (tritium is radioactive) hydrogen gas. The containment vessel of the reactor would have absolutely no problem containing the cooling gas.
  • by dulles (86837) on Wednesday March 31, 2004 @01:50AM (#8722695)
    Granted I didn't read the entire article you posted, but...

    It seems that this is plausible iff EVERY car on the road has this sort of autopilot. Human error can occur very quickly (in non-autopilot cars. alcohol?), and sometimes there really are no escape routes (unless you're on a motorcycle - the size and agility help!!).

    I therefore don't see how it would be feasible to introduce this technology so long as older cars continue to exist. No one will want to buy them initially (for safety and cost), and thus their numbers remain extremely low, further hindering autopiloting cars.
  • Re:High speed trains (Score:5, Informative)

    by Cecil (37810) on Wednesday March 31, 2004 @02:26AM (#8722897) Homepage
    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.)
  • by xheotris (628655) on Wednesday March 31, 2004 @02:37AM (#8722927)
    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.
  • by callott (306608) on Wednesday March 31, 2004 @02:37AM (#8722930)
    "The proposed HSR system would even be more expensive than driving."

    Do the figures you cite include the massive governmental subsidies of highway systems? The Federal Highway Administration alone will spend more than $32 billion in FY 2005. [gpo.gov] This goes up to $36 billion next year and doesn't include the massive expenditures by state and local governments. That's tax money coming directly out of your pocket and mine.

    There are many other non-obvious costs of cars, such as the fact that vast amounts of the space we live in is designed for use by cars instead of people. [sprawlwatch.org]

    High-speed rail is not necessarily the answer for California or anywhere else. Just remember that there is lot more to the cost of a car than the sticker price, insurance, repair costs, and fuel.

  • Re:High speed trains (Score:3, Informative)

    by fucksl4shd0t (630000) on Wednesday March 31, 2004 @03:12AM (#8723060) Homepage Journal

    any more than your car "has to have" gasoline.

    Yeah. :) Ethanol is a near drop-in replacement for gasoline (requiring only timing and mixture adjustments in most cars, and in newer cars that means replacing the computer).

    Just to make a small point, though, running out of fossil fuels isn't going to make them more expensive. Peaking worldwide is what's going to make them more expensive, because after oil drilling peaks, there won't be any growth in oil production, but the growth in demand will continue to rise. So prices will skyrocket, and our oil-based economies will go bankrupt long before we run out of fossil fuels.

    So why not convert to ethanol? It would benefit farmers, certainly. Can be produced locally, etc. I could go into economic benefits and ecological benefits and so forth, but it all come down to one thing: oil companies are huge, corrupt, and monopolistic. Think Microsoft as an oil company, and that's what we have. That's why we haven't managed to convert to ethanol, and every regulation that tries to achieve a compromise that would allow people to switch has been literally a fight and struggle to get passed.

  • by NKJensen (51126) <nkj&internetgruppen,dk> on Wednesday March 31, 2004 @03:16AM (#8723070) Homepage
    This idea is to make a car, which can travel roads and a special rail which also supplies power. High speeds are obtainable on the rail and batteries are charged while the car is on the rail. Off-rail travel will be battery powered.

    Rapid Urban Transport [www.ruf.dk] may be a good solution for large cities. And most big cities grow larger every day.

    (No, I'm not related to the inventor, Jensen just happens to be the most common name in Denmark)
  • by DoktorFaust (564453) on Wednesday March 31, 2004 @03:40AM (#8723172) Homepage
    Posted by Vancorps
    Sorry, but intelligence has nothing to do with many of the problems on the roads today
    You clearly don't have facts to back that up. I recall reading a blurb in Science about a study which showed exactly the opposite of your claim, there is indeed a correlation between IQ and driving. A quick google search and I found a reference to that study:
    An item in www.sciencemag.org on "The Practical Benefits of General Intelligence" says "people who score poorly on IQ tests also have more accidents." The study of Australian veterans under age 40 showed those with IQs of 80 to 84 had 146.7 traffic deaths per 10,000 compared with 51.3 deaths for those with IQs above 115.
  • Re:High speed trains (Score:3, Informative)

    by otis wildflower (4889) on Wednesday March 31, 2004 @03:42AM (#8723182) Homepage
    Europe has never concentrated an effort on an organized road system like the us did untill recently (if they ever did).

    Er.. the US interstate highway system was a direct result of the Autobahn.. Given that Eisenhower had firsthand experience of its efficacy in moving materiel vs more vulnerable rails, it's not surprising that it was his administration that pushed the highway system thru congress on its military necessity...

    (oh, and until recently, Europe wasn't a country ;)
  • by fucksl4shd0t (630000) on Wednesday March 31, 2004 @05:24AM (#8723510) Homepage Journal

    Yeah, it would be nice if green energy sources were available to power those cars, but they aren't so why not start on that problem first?

    That problem is already at least partially solved, if not completely. Ethanol supposedly combusts into clean products, unlike gasoline. I suspect in real-world applications it would be less perfect, but still cleaner, anyway, and renewable. (I disagree with a previous poster about farming capacity for ethanol, but so be it)

    The reason ethanol isn't "here" yet is similar to this:

    Toyota (no slouch in the efficient production arena) cannot even produce a hybrid vehicle at a profit

    In this area you are at least partially mistaken. Toyota can produce their hybrids at a profit, and they do think they could make a long-term profit if they produced them at a profit now. However, they want fast adoption of hybrids, and they think that they will make more profits off them in the long run if they get fast early adoption. So they sell them at a loss to get the adoption they need so that the demand will go up and the economies of scale will kick in and bring production costs down so their margin will resemble their existing margin on other models. *phew that was a mouthful*

    The problems with electric cars, some of which you outlined so well, are exactly in power. For electric cars to become practical, they must carry the source of power generation within them. The hybrid technology Toyota's working on may ultimately result in electric cars carrying their generators with them, I don't really know. But as you've pointed out, battery technology won't handle it. (You left out charging time on that issue, I noticed) I don't think fuel cells will be the answer either, but I could be wrong about that. ;)

    Toyota (and Honda, I might add) reached a compromise with their hybrid cars. I suspect they could build a car with a small generator running off propane or ethanol or something that used an electric motor for torque. The problem is that the oil companies would kill it. So the hybrid car is a compromise, and once Toyota can demonstrate enough demand and gain consumer confidence in the technology, the oil companies won't be able to kill a car that doesn't use oil ripped out of the ground. I'd be curious to see if Toyota and/or Honda are invested in any of the oil companies and if they've been pulling out of them at all over the last few years. It seems like a they'd invest in oil the same way HP would invest in ink.

  • Re:Whatever it is... (Score:1, Informative)

    by Anonymous Coward on Wednesday March 31, 2004 @05:57AM (#8723599)
    According to this article [go.com]it doesn't seem to be such a spot of fun.
  • by xeper (29981) on Wednesday March 31, 2004 @06:13AM (#8723631)
    I was looking for a reference to Boeing's Blended Wing Body (BWB) when I posted the previous message, now I've found it. 800 passengers.


    Well, passenger capacity for the A380-900 Single Class will be a maximum of 986.
    Howerver, normal 3-Class configuration will have a capacity off 555 (A380-800) or 656 (A380-900) passengers.
  • by bencvt (686040) on Wednesday March 31, 2004 @09:35AM (#8724425)
    Apparently whoever researched the article didn't do too thorough a job. The "driverless cabs" idea has been around for decades, and a full-scale implementation has been in use since 1972 (!) at West Virginia University. Check out the WVU Personal Rapid Transit (PRT) [wvu.edu].
  • Boom propogation (Score:3, Informative)

    by Analogy Man (601298) on Wednesday March 31, 2004 @10:23AM (#8724808)
    I worked at Boeing until 1995. There are lots of things you can do to "soften" the boom (make the N-Wave less abrupt), but physics dictates there will be an over-pressure followed by under pressure. Think of the column of air as a structure supporting the airplane (~500,000lbs). For a subsonic airplane that structure can be very broad and spread out to the sides and in front of the airplane...so the 500,000 lbs of pressure is spread out over a VERY large area. So you don't sense or feel the over pressure. Now when going supersonically that column of air holding up the airplane is swept back behind it. Or from the ground perspective, the airplane is cantilevered on MILES forward of the "arm" of air holding it up. Now that column of air has to support both the weight of the airplane (500,000 lbs) plus a huge moment. The general form of this wave is an "N". The boom passing over a house has two parts, the over pressure of the front side followed by the under pressure (approximately the length of the vehicle) shortly after. It really rocks the house of the over pressure is on the backside when the under pressure gets to the front.

    Additional challenges arise from atmospheric effects (e.g. the wave propogating above the airplane bouncing off the upper atmosphere), boom focusing (as an vehicle turns, the inside of the turn gets a more focused boom. And all this trouble is for Mach 1.7 to 2.4!

    The additional problem for hypersonic flight is that the world just isn't big enough for it to be practical. The most efficient segment is at the high altitude at high speed, but by the time you get there, you have to come down again. If there Earth was more like Jupiter in size you could cut some real time out of a trip and benefit from the high speed cruise segment.

  • by rcw-work (30090) on Wednesday March 31, 2004 @12:33PM (#8725947)
    Ekranoplans are surface effect craft or "Wing In Ground".

    Pilots usually refer to "surface effect" as "ground effect". While a wing is within half a wingspan of a surface (such as the ground or water) it can produce much more lift with less induced drag.

    The only problem is that ground and water aren't exactly flat. While a ground effect craft can temporarily climb above an obstacle, this requires a lot of pilot skill. In addition, ocean rogue waves can be upwards of twice the height of surrounding swells and can appear and disappear in seconds (they're waves of constructive interference). With this in mind, a ground-effect craft would need to be very large (at least 747 large) to fly high enough to be safe. The noise from such a large vehicle operating so closely to the ground would limit such a craft to oversea routes.

    In my opinion, we could find limited use for a ground-effect craft if we had to, but we wouldn't like it.

  • Jeebus (Score:3, Informative)

    by CKW (409971) on Wednesday March 31, 2004 @12:50PM (#8726153) Journal
    Does anyone actually realize that the "5000 mph
    test flight" was accelerated to 5000 mph using a
    rocket, and that the scramjet only ran for 10
    seconds?

    They do *not* have anything close to a bird that
    takes off under it's own power, climbs and
    accelerates to mach 5, then accelerates some more
    using a scramjet for a non-negligible amount of
    time.
  • Re:Whatever it is... (Score:3, Informative)

    by adpowers (153922) on Wednesday March 31, 2004 @06:16PM (#8730279)
    It does charge it. On this Segway page [segway.com] (under the San Francisco section), it says the HT has regenerative braking. Thus, pulling it around charges it to. My neighbor occasionally takes one home from his office (at Amazon.com) and one day he was walking home with a dead Segway. It had ran out of battery on the way back. However, by pulling it around and down the hill, it slowly gains energy back. Plus, if you wait a little while, he says it magically finds some more energy (just a little) hidden away :). So, as long as you are not /too/ far away, you can still get some use out of it.
  • by xheotris (628655) on Sunday April 04, 2004 @11:45PM (#8765883)
    "Pph" means pounds per hour. A gallon is a volumetric measurement, and for purposes of calculating weight and balance, it's converted to pounds, usually with assumed standard temp and pressure. Six pounds per gallon for avgas, approximately 6.7lbs per gal for Jet-A.

    Turboprops ARE more efficient,achieving a propulsive efficiency of over 80% versus about 60% for a high-bypass turbofan, but that efficiency fall precipitously above .5 mach.That's because they use the energy released differently. Jets and props both generate thrust, but the thrust generated by a prop is low-speed, high-mass, and they are much more efficient in thicker atmospheres. You aren't depending on accelerating small quantities of air to high speeds. This works better the higher you go, because jets run in a perpetually lean conditions. Stoichiometric values are about 14 parts air to each part gas, but jets run in the hundreds of parts of air to each part of fuel.

    The Dash 8 is powered by various Pratt & Whitney Canada turboprops, from 2,000 to 5,000 shaft horsepower, and is considered an exceptional plane. However, it's speed is limited by the fact that props can only operate efficiently at lower speeds. I haven't been able to find specific fuel consumption figures yet, but I discovered that the PW100 series engines have twin radial flow (like a turbocharger), rather than axial flow, compressors, and that acutally surprises me- I'd thought the application of radial-flow compressors was limited to engines of less than 1500 horsepower, due to flow inefficiencies. I DO know that the Honeywells on a Rockwell Turbo Commander are much more efficient than similarly powerful PT-6s for several reasons. The Honeywells are gear-driven- if you turn the prop, you can look in the intake and see the compressor turning. But the PW100 has a free turbine to drive the blades, meaning that the prop is driven by a second set of turbine blades that are not mechanically connected to the turbine and the compressor of the core engine. All the jet engine does, in this case, is generate a flow of high-temp, high-velocity air to drive the free turbine.

    As for jets flying short commuter hops like the one you mentioned, it'll never happen. Jets, even turboprops, burn way too much fuel at low level to ever achieve cost parity with piston engines. Besides, the difference in speed over 50 miles is negligible when you factor in the time spent getting to, and through, the airport. On the flight you took, I do find it odd that the pilot stayed low. How long was the flight? It might be that it was more efficient in terms of time to stay low than to climb up, then descend. A short flight makes climbing into the flight levels less useful. Flights on smaller airlines are generally more because the majors have hundreds of seats per flight to spread fixed costs across, and they get much better fuel prices, since they buy hundreds of thousands of gallons at a time... All in all, I'd rather fly slow, low, and see what's going on outside. :)

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