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Author Topic: Flying cars  (Read 34660 times)

lyner

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« Reply #25 on: 09/11/2007 00:37:44 »
This is very true - but there is a point when the complexity and cost of a safe system would become so high that corners would (literally, perhaps) be cut. Private systems would have to be around 10k and cost tens of pounds a year to maintain. That's the scary bit.
 

another_someone

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« Reply #26 on: 09/11/2007 04:13:55 »
This is very true - but there is a point when the complexity and cost of a safe system would become so high that corners would (literally, perhaps) be cut. Private systems would have to be around 10k and cost tens of pounds a year to maintain. That's the scary bit.

Complexity is a matter of perspective.

The modern motor car is an incredibly complex system, and a very high percentage of that complexity (maybe even the major part of it) is down to safety.  From crumple zones, to air bags, to stress design, to ABS braking, to seat belts and anti-dive seats.  If someone had dreamt all of this up from the technology available at the start of the 20th century, it would have been unimaginably complex, and simply infeasible.

Perceived complexity is reduced by incremental design, and modularisation.  This takes time, but is a manageable task.
 

lyner

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« Reply #27 on: 09/11/2007 22:06:15 »
OK, just stay clear of the airspace over my house.
 

Offline kalayzor

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« Reply #28 on: 18/11/2007 18:55:26 »
I'd agree that automation (aka autopilot) would definitely be necessary, and that flying cars are definitely something that could (and will) happen.  As population density goes up, there'll be a push for some alternative mode of transport that will be faster/easier than cars (since EVERYONE will be on the road, unless we become a VR society as per Isaac Asimov's "Nemesis").  Aircraft are a natural answer.

Congestion wouldn't be a problem, assuming that certain measures were taken.  There is a GPS system being developed for the general aviation community that, if combined with certain aspects of the TACAN system (used in commercial/military aircraft), would be a perfect answer.  The idea is to equip every with a GPS and have that GPS constantly transmit airspeed/altitude/heading/aircraft type data to ground repeater stations which then transmit that data to all aircraft in the vicinity, giving an effective aerial map of the surrounding area.  The TACAN system comes in with collision avoidance.  If two aircraft are on a collision course - detected by the computers of either aircraft - a signal is sent from one computer to the other commanding both aircraft to change heading/altitude in certain directions based on relative heading (right of way)/airspeed. 

What this gets down to is that you'd have to either automate the entire flight, or license people to fly these.  Given, it wouldn't be much above a sport pilot rating, but it'd be something.  You'd be constricted to flying on certain airways (so as to not interfere with the general aviation community), and you couldn't fly to controlled airports, but it'd be useful for getting from pt A to pt B a little faster, or even flying to a friend's house (fly on an airway to the general area and then have a free-flight area - if 'twas a convention, you'd have to have controlled airspace instead, but you get the idea).

As for cost, yep, it'd be a mite more.  On the other hand, there are gyrocopters out there for $17k!  As powerplant technology improves, I don't doubt that these would get cheaper, and I think that a cheap aircraft with rudimentary controls/instrumentation and an autopilot could be made without getting too expensive.
 

another_someone

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« Reply #29 on: 18/11/2007 20:01:25 »
As you say, it is not at all inevitable that there will be an increasing need for human transportation, and telecommunication will obviate a lot of the need for human movement.  There will continue to be a need for the transport of goods and raw materials, but that is another matter.

As I have indicated before, air travel does not always present itself as a means of increasing traffic density (you cannot see airliners getting anywhere like as near each other as you might see railway trains of similar passenger carrying capacity).  This is not merely because of the complexities of traffic control in 3 dimensions, and safety requirements for vehicles travelling at just under the speed of sound, but also because aircraft, by their very nature, need clean air to travel in, yet by their very nature will disturb the air they travel through, thus require to provide sufficient distance between themselves to allow the air to return to a equilibrium before they enter a given airspace.  This distance can be reduced when travelling in strict formation (as birds do when they are flying in formation), but this only works where you regard the entire formation as a single large unit, all travelling in the same direction, and cannot be used for vehicles moving in different directions to each other.
 

lyner

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« Reply #30 on: 18/11/2007 22:02:29 »
You could get a very high density of traffic with a multilayer tracked system - automatic, of course. It would have the advantage that it can all slow down and stop quite safely any time. Not quite so sexy but makes sense.
 

another_someone

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« Reply #31 on: 19/11/2007 00:48:45 »
The problem with tracked systems, although simple and well understood, are extremely expensive to build and maintain.  For all of the concerns about the cost of building flying machines, the cost is predominantly in the cost of the vehicle themselves, and the cost of the supporting infrastructure, while certainly non-zero, is still very small compared to the infrastructure costs of maintaining a tracked system.

This is not to dismiss tracked systems, only to suggest that we do need to find some way of constraining the infrastructure costs better than we do at present.
« Last Edit: 19/11/2007 00:51:53 by another_someone »
 

lyner

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« Reply #32 on: 19/11/2007 10:02:27 »
Good traffic control would limit the amount of track needed.
I think you guys spend too much time watching films like The Fifth Element.
In any case, most people will be networking before long - no need to go anywhere - just walk to your local pub.
 

lyner

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« Reply #33 on: 19/11/2007 10:04:04 »
A_s: Why are you a newbie. all of a sudden? Have you been round the clock?
 

another_someone

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« Reply #34 on: 19/11/2007 13:13:47 »
A_s: Why are you a newbie. all of a sudden? Have you been round the clock?

No, the account was deleted and recreated - complex story.
 

another_someone

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« Reply #35 on: 19/11/2007 13:26:50 »
Good traffic control would limit the amount of track needed.

That is an argument that is still used today to squeeze more from the existing roads and railway networks, but has still not solved current congestion problems.  Aside from congestion issues, there still remains the cost of maintenance of the current network (constant resurfacing of roads, and repairs of the rails - failure to do either adequately leading to accidents), and still new roads need to be built whenever new facilities need to be services (new estates, or new airports, etc.).  All of this is extremely expensive, and rarely done adequately.

If you compare the relative infrastructure cost between running more flights between London to Paris, and building the Eurostar network, the cost of the flights is minuscule.  Furthermore, the only real infrastructure cost involves the total traffic volumes at each endpoint, but there no significant cost involved in rerouteing traffic (i.e. assuming London, Frankfurt, and Paris all have sufficient endpoint capacity, whether the flight is going from London to Paris, or London to Frankfurt matters not, but laying new track for a direct train route from London to Frankfurt is still expensive).

Another problem with trying to eke ever more capacity out of the same infrastructure by simply improving efficiency of utilisation of the infrastructure is that the network ever more loses redundancy and resilience, so that a single failure of the network (e.g. an accident, or bad weather) creates ever greater degradation on the network.  Creating networks with lots of redundancy, because the network infrastructure costs have been reduced sufficiently to allow this to be done, makes it easy to reroute traffic around points of network failure.

Another issue to consider is what is meant by flying?  The original question supposed a full 3 dimensional traffic management scheme as a means of alleviating congestion.  If we are merely looking at ways of alleviating the cost of laying track on a 2 dimensional traffic management scheme, this could be achieved simply by using flying heights from 6 inches to 10 feet above the surface (e.g. as in hovercraft), and these do not carry the same safety implication that flying 30,000 feet above the surface might do.
« Last Edit: 19/11/2007 14:49:38 by another_someone »
 

lyner

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« Reply #36 on: 19/11/2007 17:52:39 »
Quote
this could be achieved simply by using flying heights from 6 inches to 10 feet above the surface (e.g. as in hovercraft), and these do not carry the same safety implication that flying 30,000 feet above the surface might do.
That would be fine; I could go for some such system but I don't think that was what the original post was about.  The spirit of the post was very Buck Rogers and that is a great fun idea. However,  your system doesn't give direct routes because it shares space with buildings.  It is more like multi lanes, stacked vertically.

I don't think you are taking into consideration, enough, the problem of actually stopping and waiting in any mass airborne system.
I have the same problem when in my boat, even. There's no such thing as a handbrake. The anchor is very much not a handbrake and is very often not possible to use  and, even when you can, it involves a lot of preparation and faffing around.
A ground-based system is gloriously fail safe. Nothing else is. We make up for this in the present  flying environment by making it very exclusive and very expensive.  Of course, if it were just you and me with the air cars it would be a terrific system. It's all the other punters I'm hesitant about. Just imagine the Arthur Daley  air car!
 

another_someone

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« Reply #37 on: 23/11/2007 03:16:30 »
That would be fine; I could go for some such system but I don't think that was what the original post was about.  The spirit of the post was very Buck Rogers and that is a great fun idea. However,  your system doesn't give direct routes because it shares space with buildings.  It is more like multi lanes, stacked vertically.

I agree - it is looking at a different problem.

I don't think you are taking into consideration, enough, the problem of actually stopping and waiting in any mass airborne system.
I have the same problem when in my boat, even. There's no such thing as a handbrake. The anchor is very much not a handbrake and is very often not possible to use  and, even when you can, it involves a lot of preparation and faffing around.

I think that you are overstressing this issue.

Waiting in traffic is a problem for poorly managed traffic, but proper traffic management systems (available only with proper robotic control under guidance from an integrated traffic management system) should substantially alleviate this problem.

Where you might have more legitimate argument is with regard to susceptibility to wind gusting when operating in confined spaces (such as dense traffic patterns).  No traffic management system can anticipate wind gusts.

A ground-based system is gloriously fail safe. Nothing else is. We make up for this in the present  flying environment by making it very exclusive and very expensive.

That is the point, flying is actually not that expensive at all (when you take into account passenger miles).  Flying becomes expensive at short distances, but the moment you wish to travel over 1000 miles, you'd be hard put to find a cheaper way of doing it than by air.
 

Offline kalayzor

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« Reply #38 on: 23/11/2007 15:54:46 »
Ach...this is what I get for missing time due to having my wisdom teeth out.

I'm not too sure if I'm seeing the waiting in traffic argument here...I'm envisioning something more along the lines of fixed-wing aircraft with S/VTOL capability than helicopters.  Helicopters aren't really ideal for civilian travel (save in cities or areas where their landing pads can be isolated on top of skyscrapers or in the middle of no where (aka Alaska)) due to the immense amount of noise and vertical wind shear that they whip up.  I really don't see the need for a pure helicopter/hover system...anything that can at least made to hold a controlled vertical descent or land in <100 feet without destroying the airframe should be fine.

What could be done is to have a set schedule of usage times for these established airways, hence developing formations that could be tracked via GPS.  Autopilot control could keep the formation in order with enough separation (vertical or horizontal (abreast or astern)) so, given a hundred feet of separation and an autopilot's response time, I'd venture that anything short of a hurricane-strength gust could be accounted for.  Given, there would need to be an upper limit to the system's use in windy/stormy environments, at which point only appropriately rated pilots would be allowed to fly.  We already have an international air navigation system in place (VOR and VORTAC stations)...it wouldn't be too much more (in the long run) to add on a automated GPS-run controller to each one.

Also, about that fail-safe ground based system...I've heard of a lot of traffic accidents.  There is a lot more space in the air that we can use to keep folks from attempting to occupy the same point.
 

lyner

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« Reply #39 on: 23/11/2007 17:11:44 »
Quote
I've heard of a lot of traffic accidents.
These are because people can't control vehicles effectively and they don't concentrate.
Have there been many with completely automated systems?

Do you really trust other people to be flying over your head in their little run-arounds, gossiping to their passengers and forgetting to have the vehicle serviced?
At least you are relatively safe on the pavement, these days.
 

Offline kalayzor

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« Reply #40 on: 23/11/2007 18:04:36 »
That's why you automate the whole thing and set reasonable limitations on use.  Aircraft autopilots are pretty danged good these days.

I'm thinking that completely automated cars aren't around yet because there A) isn't enough room on the roads for a GPS system (uncertainty in measurement) - and there's lots of room to play with just 6,000 feet upstairs - and B) it'd cost too much to redo all of the roads currently in existence.  However, building this up from "scratch" - so to speak, since almost all of the elements are already in existence - would cost significantly less.  As mentioned before, the main cost is that of the aircraft itself, and that wouldn't even be factored into the installation, since that's a personal cost.  The only long-term one would be maintaining the facilities.

As for vehicle maintenance, how many folks forget to have their car serviced?  After a point, 'tis illegal not to, right?

That could be something else factored into the system.  The navigation system (or even a program initiated by the ignition system) could query a locked memory file aboard the vehicle and makes sure that the aircraft is within legal operating limits (diagnostic check of systems as well as a check of the last inspection) before takeoff.

If you want a different look at this, do you trust the general aviation community?  They're flying overhead in Cessnas and Pipers, likely just running from one airfield to another for a cup of coffee and a bit of gossip.  The aircraft, to the everyday person, would be another mode of transportation that would require the same attention as a car does today.
 

another_someone

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« Reply #41 on: 23/11/2007 21:46:22 »
I'm not too sure if I'm seeing the waiting in traffic argument here...I'm envisioning something more along the lines of fixed-wing aircraft with S/VTOL capability than helicopters.  Helicopters aren't really ideal for civilian travel (save in cities or areas where their landing pads can be isolated on top of skyscrapers or in the middle of no where (aka Alaska)) due to the immense amount of noise and vertical wind shear that they whip up.  I really don't see the need for a pure helicopter/hover system...anything that can at least made to hold a controlled vertical descent or land in <100 feet without destroying the airframe should be fine.

So you are talking about a transportation system that would operate in rural, low population density, areas.  You could not build 100 foot runways all over a major metropolitan complex.

This might work for Australia (where air transport was always important in the outback), but won't work anywhere in Europe.

Even in rural areas, most people live in small communities, and would not expect to have a 100 foot runway for each house, but would share a community runway, so still requiring a support infrastructure to and from the airstrip.
 

Offline kalayzor

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« Reply #42 on: 23/11/2007 22:24:20 »
Yes and no.  I'm talking about using what makes the most sense where it makes the most sense -- in other words, allowing VTOL in cities/locations, and STOL in rural areas where you can grab yourself 100 feet (or less, as technology develops (namely, airfoil design) to allow for slower approach speeds) of grass, roadway, or anything of the sort.  You don't need a runway.  You will need a clear bit of land, yes, but that's something to factor into design of the aircraft again.  Do you make it such that the wings fold (such as found in naval aviation), the landing gear powered, and the aircraft able to operate on roads for short distances at slow speeds?  Agreed, some folks might want a runway - sometimes it might be needed, but those places may also provide an economical spot for it (small urban areas, etc).

The fixed wing deal is also for maintenance -- fixed wing aircraft can survive longer than rotary winged aircraft (especially their props!).

I'm not saying that VTOL is a bad idea -- I'm just saying that a pure VTOL machine isn't the way to go.
 

another_someone

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« Reply #43 on: 23/11/2007 23:46:38 »
Yes and no.  I'm talking about using what makes the most sense where it makes the most sense -- in other words, allowing VTOL in cities/locations, and STOL in rural areas where you can grab yourself 100 feet (or less, as technology develops (namely, airfoil design) to allow for slower approach speeds) of grass, roadway, or anything of the sort.  You don't need a runway.  You will need a clear bit of land, yes, but that's something to factor into design of the aircraft again.

If you are looking to provide a transportation system for 6 million city dwellers, and half a million in the surrounding rural areas, then the commercial interest will be in supplying those 6 million customers, and the other half million will merely be an add-on.

Furthermore, if you have a fully managed system, with predictive traffic management, then that means you need to manage the landing/takeoff areas as well.  You cannot just allocate an unprepared grass field over which you have no control, and bring the aircraft onto finals, and just as it is about to touch down, an antelope runs across the field, or the local yocal decides to use the runway as a shortcut to where he wanted to drive his pick-up.  You also need to ensure that the airstrip is fairly immune to weather, and the landing strip does not suddenly become marshland after a heavy rain.

Using VTOL will still demand that the landing strip is secure and remains usable in most weather conditions (and when it is not usable, it is predictable in that the system can determine that the field is unfit for use before a vehicle tries to use it rather than afterwards).  Nonetheless, the fact that VTOL uses less land makes it easier to manage, and potentially this could be a roof top, which is a more easily managed area than something at ground level (antelopes and yocals with pick-ups don't usually get up on roof tops).

If one is going to be really innovative, one could speculate about a system where the aircraft to not land or takeoff themselves, but are picked off a parking lot by a giant crane, which then catapults them into the air; and when the aircraft wishes to land, it connects in mid air with this same crane, which then places them down on a parking lot.

The other alternative is to use separate ducted fans for takeoff and landing, these becoming redundant in level flight.

Most proposals for 'flying cars' seem to revolve around the use of swivelling ducted fans, using downthrust from the fans for takeoff and landing, and converting to winged flight, and swivelling the fans to provide rearward thrust, when in level flight.

Do you make it such that the wings fold (such as found in naval aviation), the landing gear powered, and the aircraft able to operate on roads for short distances at slow speeds?  Agreed, some folks might want a runway - sometimes it might be needed, but those places may also provide an economical spot for it (small urban areas, etc).

Cannot see how you are going to transmit power down to the wheels of an aircraft - possibly a small electric motor embedded in the hub of each wheel, but it will have very little power, and the whole system is not well suited to traction.

Even if you could get the power to the wheels, the whole vehicle would have a very, very, high centre of gravity, and would be a serious liability on the roads (aside from not being able to fit under low lying structures, such as power cables or low bridges).

Another aspect of folding wings is that they generally would have be be fairly short, which mean a high wing loading, which means poor low speed performance (naval aircraft can only be considered as STOL by virtual of using catapults, and very, very, powerful jet engines).

The fixed wing deal is also for maintenance -- fixed wing aircraft can survive longer than rotary winged aircraft (especially their props!).

Agreed - although gyrocoptors (which generally are short takeoff/vertical landing) should not be high maintenance, although they have other limitations (not least of which is having to carefully manage the centre of gravity of the aircraft - although this is to some extent true of all aircraft).
 

Offline kalayzor

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« Reply #44 on: 24/11/2007 02:02:40 »
If you are looking to provide a transportation system for 6 million city dwellers, and half a million in the surrounding rural areas, then the commercial interest will be in supplying those 6 million customers, and the other half million will merely be an add-on.

Agreed, but why would an intracity system (hence necessitating primarily VTOL aircraft manufacturing) be the focus?  I'd think that you'd want something that could travel between cities or to/from them...not within them - hence necessitating something that's good for distance travel (and hence allowing a greater focus on STOVL capability than solely VTOL - you'd still need it, don't get me wrong, but it wouldn't be as if you're building a helicopter).  I like the compromise of a ducted system (akin to what in used on the F-35's main engine save done over for props)...it'd require some engineering, but I think it could be done (and efficiently so, for all involved).

As for the fully managed system - to an extent.  That's why you necessitate licensing for all users -- just like with cars -- and put aircraft on manual once they have adequate separate within a particular zone that includes their laid-in destination (keeping them in practice with maneuvering/landing/takeoff).  Computers can't beat human judgment on some issues, agreed, so let's not put them in the pilot's seat the whole way.

I'm assuming that there are roads near the place in question (for soaked fields - that was just an option).  While you could use the main engines to taxi, some sort of PTO system would be a better choice.  I'm supposing that it'd be possible to harness the drive motor to the landing gear, though the gears probably wouldn't engage until the aircraft was on the ground (a manual control).

A "parking lot" of sorts would be helpful, but that wouldn't make these cars the personal transport that we're thinking of, right?  Ground cars would still be necessary for 100% of all travel done in rural areas.

Another aspect of folding wings is that they generally would have be be fairly short, which mean a high wing loading, which means poor low speed performance (naval aircraft can only be considered as STOL by virtual of using catapults, and very, very, powerful jet engines).

Had forgotten about aspect ratios for a moment there.  However, you could build things such that the wings A) fold aft (after rotating 90 degrees - if you've ever seen a sailplane packed into its trailer, like that, save with that the wings are still attached) and fold upon themselves again (perhaps with a greater section of the wing going forward to balance things out) to keep the aircraft relatively short and able to manage a turn with only a little difficulty.  They aren't meant to be ground vehicles, so we shouldn't push them to be -- at least not at the current level of technology (or that designable in the next 20 years or so (I'm assuming that's the idea here anyhow)).
 

another_someone

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« Reply #45 on: 24/11/2007 03:09:10 »
If you are looking to provide a transportation system for 6 million city dwellers, and half a million in the surrounding rural areas, then the commercial interest will be in supplying those 6 million customers, and the other half million will merely be an add-on.

Agreed, but why would an intracity system (hence necessitating primarily VTOL aircraft manufacturing) be the focus?  I'd think that you'd want something that could travel between cities or to/from them...not within them - hence necessitating something that's good for distance travel (and hence allowing a greater focus on STOVL capability than solely VTOL - you'd still need it, don't get me wrong, but it wouldn't be as if you're building a helicopter).

But intercity air transport already exists, and while you may look at expanding it, and making it more flexible, it still more about providing a mass transit system than about applying personal transport.  Personal transport is required for end to end journeys, but when you deal with hub to hub journeys, then mass transit systems are more than adequate (i.e. aircraft that carry 50+ people, rather than individuals).

As for the fully managed system - to an extent.  That's why you necessitate licensing for all users -- just like with cars -- and put aircraft on manual once they have adequate separate within a particular zone that includes their laid-in destination (keeping them in practice with maneuvering/landing/takeoff).  Computers can't beat human judgment on some issues, agreed, so let's not put them in the pilot's seat the whole way.


The problem is that if you have a hybrid system, part manual and part computer controlled, do you not have the worst of both worlds - a computer controlled system that tries to integrate a human component.

The point about a computer controlled system is that it must have total authority over their environment.  If you complain that computers lack judgement, then how are they to judge what a human operator in their midst that is operating in manual mode is going to do?

And bear in mind what has already been said, that car drivers have far lower levels of training than aircraft pilots, and the idea is that if we are to have as many pilots as we presently have drivers, then we have to reduce the training requirements.

I'm supposing that it'd be possible to harness the drive motor to the landing gear, though the gears probably wouldn't engage until the aircraft was on the ground (a manual control).

It is not the gear box that concerns me but the primary drive shaft delivering power to the wheels - might just be possible with a fixed undercarriage, but are you going to forgo  retractable undercarriages?

A "parking lot" of sorts would be helpful, but that wouldn't make these cars the personal transport that we're thinking of, right?  Ground cars would still be necessary for 100% of all travel done in rural areas.

The term 'parking lot' can have a number of interpretations - your driveway could be regarded as a parking lot, but it depends on whether it can be integrated into the system.

Looking at the concept of a crane, if it was sufficiently large, you could have one crane for each block of buildings, and deliver the vehicle into any driveway within that block.

Had forgotten about aspect ratios for a moment there.  However, you could build things such that the wings A) fold aft (after rotating 90 degrees - if you've ever seen a sailplane packed into its trailer, like that, save with that the wings are still attached) and fold upon themselves again (perhaps with a greater section of the wing going forward to balance things out) to keep the aircraft relatively short and able to manage a turn with only a little difficulty.  They aren't meant to be ground vehicles, so we shouldn't push them to be -- at least not at the current level of technology (or that designable in the next 20 years or so (I'm assuming that's the idea here anyhow)).

There is another scenario - detachable wings - leave the wings at the airport, and pick them up again on the way out.  You could even leave the undercarriage behind, so you have a fairly conventional small car that drives up to a partial airframe, connects up with the wings and undercarriage, and flies off.
« Last Edit: 24/11/2007 03:11:16 by another_someone »
 

Offline kalayzor

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« Reply #46 on: 25/11/2007 04:13:47 »
But intercity air transport already exists, and while you may look at expanding it, and making it more flexible, it still more about providing a mass transit system than about applying personal transport.  Personal transport is required for end to end journeys, but when you deal with hub to hub journeys, then mass transit systems are more than adequate (i.e. aircraft that carry 50+ people, rather than individuals).

Intercity air transport does exist, but it isn't localized in the sense that you'll still need the car.  What if your destination is relatively close to the city, but not enough to merit flying straight there?  Why not fly there, and then rent the aircar for the rest of 0the voyage - same for flying into the major city.  You still save the money, you still get to go more or less directly and fairly swiftly to your destination.

The problem is that if you have a hybrid system, part manual and part computer controlled, do you not have the worst of both worlds - a computer controlled system that tries to integrate a human component.

The point about a computer controlled system is that it must have total authority over their environment.  If you complain that computers lack judgement, then how are they to judge what a human operator in their midst that is operating in manual mode is going to do?

Allow me to reexplain.  I'm saying that computers are fine for controlling and I'm saying that humans are sometimes better - the key is to play to their strengths.  Computers don't fatigue, humans do.  Humans can make rapid and highly situational judgments in wide and varied, computers cannot.  Whilst in the airways, computers are a good choice - low amount of variables, easy handling (wind factors can be adjusted for), no fatigue in the system.  Whilst landing/taking off/maneuvering to land (after the vehicle has exited the airway), humans are the best choice (judgment).  Neither component interferes with the other unless manual control is deemed necessary by the situation (aka emergencies).

And bear in mind what has already been said, that car drivers have far lower levels of training than aircraft pilots, and the idea is that if we are to have as many pilots as we presently have drivers, then we have to reduce the training requirements.

As much as I dislike the idea, yeah.  I'd like everyone to be trained to at least the minimum for the current sport pilot license, though.  It'd be a little harder to train folks, but possible.

It is not the gear box that concerns me but the primary drive shaft delivering power to the wheels - might just be possible with a fixed undercarriage, but are you going to forgo  retractable undercarriages?

We could...but I don't see how it'd be a problem if 'twas kept retractable, so long as everything was kept disconnected until deployment/touchdown.  Sure, you'd have to get it to align each time, but that could be done.

The term 'parking lot' can have a number of interpretations - your driveway could be regarded as a parking lot, but it depends on whether it can be integrated into the system.

Looking at the concept of a crane, if it was sufficiently large, you could have one crane for each block of buildings, and deliver the vehicle into any driveway within that block.

I'm trying to interpret what you brought up.  Tell me what you're saying if I got it wrong.

That'd be one heck of a crane, though.  And one heck of a hard way to land!  Have you ever seen the system that the British built to do that with Harriers?  That's some touchy flying.

I'm think that, even if you don't use it as the landing system in and of itself, it'd still be more infeasible that landing directly at home.  Community airstrips would be good but, as you said, that's a lot of infrastructure.  I guess it could be an "as needed" item, however, that would be brought before the township in question.

There is another scenario - detachable wings - leave the wings at the airport, and pick them up again on the way out.  You could even leave the undercarriage behind, so you have a fairly conventional small car that drives up to a partial airframe, connects up with the wings and undercarriage, and flies off.

That'll work.  Someone tried that one before - the Hall (or Convair) Aerocar if you want to look it up - though the market wasn't in for it at the time.  The only thing you're running into again is having the community airport, which I've discussed above.  Sounds good.
 

another_someone

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Flying cars
« Reply #47 on: 25/11/2007 14:51:07 »
Intercity air transport does exist, but it isn't localized in the sense that you'll still need the car.  What if your destination is relatively close to the city, but not enough to merit flying straight there?  Why not fly there, and then rent the aircar for the rest of 0the voyage - same for flying into the major city.  You still save the money, you still get to go more or less directly and fairly swiftly to your destination.


You have already suggested that some road transport will be required in the final stage of the journey (because you will not be flying directly into your driveway or rooftop).  If I read you correctly, you are now suggesting a 3 level journey - road transport to the point of local flight, then from local flight to intercity flight.  This sounds like it will be adding complexity without much benefit.

Allow me to reexplain.  I'm saying that computers are fine for controlling and I'm saying that humans are sometimes better - the key is to play to their strengths.  Computers don't fatigue, humans do.  Humans can make rapid and highly situational judgments in wide and varied, computers cannot.  Whilst in the airways, computers are a good choice - low amount of variables, easy handling (wind factors can be adjusted for), no fatigue in the system.  Whilst landing/taking off/maneuvering to land (after the vehicle has exited the airway), humans are the best choice (judgment).  Neither component interferes with the other unless manual control is deemed necessary by the situation (aka emergencies).

I would argue the contrary.  We already have commercial airliners that can be landed with MLS without any human intervention, and we have fly by wire aircraft that have computers controlling situations that are simply too complex for humans (even well trained humans) to manage.

The issue with computers is not that they cannot make complex decisions - they can make them as well, and more consistently, than humans.  The problem at present is with the lack of sophistication in sensory input (humans can still process vision, sound, and touch, far better than any machine - at least that is so at present, although the gap is closing very rapidly).

And bear in mind what has already been said, that car drivers have far lower levels of training than aircraft pilots, and the idea is that if we are to have as many pilots as we presently have drivers, then we have to reduce the training requirements.

As much as I dislike the idea, yeah.  I'd like everyone to be trained to at least the minimum for the current sport pilot license, though.  It'd be a little harder to train folks, but possible.

As has been pointed out already, even with the present training for drivers, there are large numbers of accidents happening every day, simply down to human error.  The same is true with sports aviation pilots, but because there are relatively so few of them, the overall death toll remains small.

It appears to me that you live in a fairly rural area, with low road traffic densities (and even lower air traffic densities).  If you were to try driving in a typical large European city, you'll quickly see how much more training is required for to drive in high traffic densities (and the reason why we still have about 3,000 deaths (and 33,000 serious injuries) on our roads each year from a population of 60 million).  Would you really trust all these people with an aeroplane (even with extra training)?  And who will pay for all this extra training?

It is not the gear box that concerns me but the primary drive shaft delivering power to the wheels - might just be possible with a fixed undercarriage, but are you going to forgo  retractable undercarriages?

We could...but I don't see how it'd be a problem if 'twas kept retractable, so long as everything was kept disconnected until deployment/touchdown.  Sure, you'd have to get it to align each time, but that could be done.


That sounds like complexity waiting to go wrong (failure for the undercarriage to function properly is not that uncommon, and if you make the whole thing more complex, it will only get worse).

Aside from that, the normally expected stresses for which an undercarriage is designed for are very different from the stresses needed to apply traction to the vehicle.  There is also the enhanced risk of accidental damage to the undercarriage when driving on the roads, and while a totally destroyed undercarriage is not a problem (it just needs to be replaced or fixed), a minor damage may not be considered significant enough to repair, but yet may turn out to be catastrophic at a critical point in a future landing.


The term 'parking lot' can have a number of interpretations - your driveway could be regarded as a parking lot, but it depends on whether it can be integrated into the system.

Looking at the concept of a crane, if it was sufficiently large, you could have one crane for each block of buildings, and deliver the vehicle into any driveway within that block.

I'm trying to interpret what you brought up.  Tell me what you're saying if I got it wrong.

That'd be one heck of a crane, though.  And one heck of a hard way to land!  Have you ever seen the system that the British built to do that with Harriers?  That's some touchy flying.

I'm think that, even if you don't use it as the landing system in and of itself, it'd still be more infeasible that landing directly at home.  Community airstrips would be good but, as you said, that's a lot of infrastructure.  I guess it could be an "as needed" item, however, that would be brought before the township in question.

OK, the idea I have (and I am not suggesting it is a solution, only an idea I've played with for a while) is to have a large, but highly segmented, crane.

Each segment would be a module of maybe about 10 metres (or maybe even less) in length, and attached to its neighbour through a joint that allows freedom of movement in two directions.  What you have here is a kind of giant snake, with a very high degree of flexibility.

Clearly, much as each segment must be able to lift its own weight, it would not be practical to provide sufficient power to each segment that it would be able to lift all of the segments beyond itself.  Thus, rather than relying on a simple application of force at one point in the chain to lift the entire chain in the air, it will use its own inertia, and generate a kind of wave function in order to lift the entire chain up (thus, it is not a crane that could usefully keep something suspended in the air, but it can carry things dynamically through the air).

The aircraft itself will fly a gradual descent (or even a level flight) precisely guided by electronic means, while the crane, also guided by electronic means, will be guided onto a convergent course to the aircraft, and lock on to it when in flight.  Then the crane will pull the aircraft gently out of the air and guide it onto the landing platform.

For takeoff, the same undulating motion will lift the body of the crane up, while the tip of the crane is carefully guided to the parked aircraft; it will then lock onto the aircraft, lift itself into the air again, and throw the aircraft into flight (rather like a glider might be launched with a winch).

In principle, because the system is composed of small, easily fabricated, standard modules; costs can be kept low, while allowing for a highly variable configuration in the end product.

Nonetheless, I am not saying that I do not foresee problems with the device (even if the concept of the undulating crane can be made to work).  The large number of components constantly swishing around in all directions, and multiple small sources of power, could make could be quite noisy, which may offend the sensibility of the local residents.  Then there is the problem that it can only manage one takeoff or landing within a given block at any one time; so if everybody in the block want to go to work at once, some will have a long wait at the end of the queue.  Then there is the problem as to whether an aircraft should be attached to from below (better for handling in the air) or from above (better for putting down on, or picking up off, the ground), or is some way can be found to change the attachment point while the aircraft is being manipulated by the crane (e.g. an attachment point on the nose of the aircraft when the aircraft is being dragged through the air, and one on the top that is used for ground handling).

There is another scenario - detachable wings - leave the wings at the airport, and pick them up again on the way out.  You could even leave the undercarriage behind, so you have a fairly conventional small car that drives up to a partial airframe, connects up with the wings and undercarriage, and flies off.

That'll work.  Someone tried that one before - the Hall (or Convair) Aerocar if you want to look it up - though the market wasn't in for it at the time.  The only thing you're running into again is having the community airport, which I've discussed above.  Sounds good.

There seem to be several designs along the same concept (aome allow the detached wings to be towed behind the car, while others assume the wings will be left at the airfield).

http://en.wikipedia.org/wiki/AVE_Mizar
http://en.wikipedia.org/wiki/Fulton_Airphibian
http://en.wikipedia.org/wiki/Aerocar_2000

All seem to be based upon a fairly powerful (and hence large) car to which you add wings, but sounds like they would be better cars than aeroplanes; when it looks like what you want is the converse.  Thus I might think of, rather than having a large car, with a large powerplant, maybe have a very small car, that was electrically driven (for short distances), and have the big engine built into the airframe (and able to charge the batteries of the small, fibreglass, low speed car), thus allowing you to better optimise the machine for flying than for driving.
 

Offline kalayzor

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Flying cars
« Reply #48 on: 25/11/2007 19:39:26 »
You have already suggested that some road transport will be required in the final stage of the journey (because you will not be flying directly into your driveway or rooftop).  If I read you correctly, you are now suggesting a 3 level journey - road transport to the point of local flight, then from local flight to intercity flight.  This sounds like it will be adding complexity without much benefit.

OK, let's take this all in context.

If you're flying into an extremely rural area (think New Hampshire rural with trees everywhere), then yes, you'd have to find an open spot to land in...such as a roadway or an area cleared and hardened for the purpose.  Then we'll get into the fact that you still need to drive home, since 'tis impossible to fly there anyhow (or get craned there).  Makes sense, no?

However, if you're flying into a less rural/somewhat urban area, you probably could land AT home/on a road about fifty meters from your house, depending on what variety of aircar you bought/is available (STOVL).

If you're flying intercity, the best bet would be to take said existent transport to within the city and then airtaxi to your destination simply because of economy -- mass transit.

You can't have one system for everything -- it'll have to change depending on the area, which is also what I'm arguing for the navigation systems.  Either you or someone else on here stated something before to the effect that regardless of computer precision in flight, it cannot judge things such as the condition of the landing field, etc.  What if the engine fails and you need to land out?  A human is going to have to do that (unless you can guarantee an airfield with an MLS installed within gliding distance of every airway...which you could do in many places (if it gets mandated by the FAA for all FOBs at some point) - but NOT all, especially in wooded/mountainous areas...in which case your only chance for survival lays with the pilot).

Enough of that, but we'll be touching on MLS again in a second.

Training...do you have a copy of the FARs (CFRs, whatever you want to call 'em) around?  Look in part 61.56a -aka flight reviews (annually, though, not biennials).  That's the key.  I'm not saying 'tis a cure-all, but it'll knock out bad habits that often lead to accidents/incidents (by the way -- something that you might enjoy: CFR 61.153c, eligibility requirements for an ATP rating: "be of good moral character." That appears for no other rating that I've yet looked at.).

Besides this, the absolute minimum training requirement for the sport pilot license is 30 hours of instruction -- that's not that much below what's required for a private license (40 hrs in airplanes)!  Looking at the PTS for sport pilot, I'm thinking that 'tis possible to get folks adequately trained.  The NTSB hasn't released accident data for sport pilots (nothing since 2002, or so I've found, and sport licenses are a fairly recent development), and there isn't much discussion online about it (AOPA, Flying magazine, Google, etc).  Where are you getting your accident data from?

Who's going to pay?  Those who wish to use the system.  Do you have to pay for a driver's license?  No, you don't HAVE to...but you do for the convenience.  This'll cost more, true, but for a greater convenience.  Capitalism!  Not that I'm a fan of the system, but that's what we live in (right now).

OK...the crane.  I'll grant you that 'tis QUITE an idea...an interesting one to...but I really don't think that a crane (any at all) is the way to go, if only for reasons of economy, the fact that you'd have to pass its payload over inhabited areas (do you trust that to be failsafe?), that you couldn't use it for anything BUT returning aircars to their respective homes...all of these things that you could easily do with the aircar design.

Either have separable wings (which I can vouch for as being safe...as can every single glider pilot in the world who connects everything properly) or foldup.  My vote's with the detachable option.  Very much with the detachable option.

So, let's see what we have here:

Short range fiberglass/carbon fiber composite electrically powered car that can attach to a set of wings/tail assembly as well as a powerplant (which recharges the car batteries when in operation).  Aircar is then STOVL capable (or VTOL, depending on starting location (air taxi (I'm going to revive the VTOL concept for them, since they're short range only))), is automatically flown to an airway if need be (determined from a preprogrammed destination) and thereby to the destination area where it is landed, unless the area lacks a MLS in which case the PIC will then assume control and land the aircraft (as would also be done in the event of an emergency outside of an MLS).  Car will detach or aircraft will be driven to park (depending on landing location (home or local airfield).

How abouts that?
 

another_someone

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Flying cars
« Reply #49 on: 25/11/2007 21:22:04 »
OK, let's take this all in context.

If you're flying into an extremely rural area (think New Hampshire rural with trees everywhere), then yes, you'd have to find an open spot to land in...such as a roadway or an area cleared and hardened for the purpose.  Then we'll get into the fact that you still need to drive home, since 'tis impossible to fly there anyhow (or get craned there).  Makes sense, no?

However, if you're flying into a less rural/somewhat urban area, you probably could land AT home/on a road about fifty meters from your house, depending on what variety of aircar you bought/is available (STOVL).

If you're flying intercity, the best bet would be to take said existent transport to within the city and then airtaxi to your destination simply because of economy -- mass transit.

So, from my position, where I have a commercial airport about 4 or 5 miles away, another two about 40 miles away, and one more which (by train) through the city centre is probably about 80 miles away, although taking the ring road around London would be considerably further.

Clearly, those commercial airports presently support city to city traffic, so where would you see my using an airtaxi or flying car?

There used to be a small airfield for private flying about 20 miles from me, but it has now (as with so many small airfields) been closed down as it was more profitable to build houses and business parks on that land than keep it for the small, and very select, group of people who fly private or executive aircraft.

At present there is enormous political pressure to build another 2 million houses in the south-east of England (the closure of the airfield came before the pressure for housebuilding became a political priority), so every inch of land that can be allocated to housing is being done so (at the expense of every other land use).

I realise that this is very different from New Hampshire, even though I have never actually visited New Hampshire (visited the old Hampshire, but not the new one :)).

You can't have one system for everything -- it'll have to change depending on the area, which is also what I'm arguing for the navigation systems.  Either you or someone else on here stated something before to the effect that regardless of computer precision in flight, it cannot judge things such as the condition of the landing field, etc.  What if the engine fails and you need to land out?  A human is going to have to do that (unless you can guarantee an airfield with an MLS installed within gliding distance of every airway...which you could do in many places (if it gets mandated by the FAA for all FOBs at some point) - but NOT all, especially in wooded/mountainous areas...in which case your only chance for survival lays with the pilot).

It rather depends on the context.  If you are flying in poor visibility, then one way or another, you are going to have to rely on electronic navigation to get you down, or you are dead.  Whether that be MLS, or it be GPS and ground mapping radar, it is not going to be eyeball navigation.

Clearly, this may be less of a problem if one restricts flying to VFR, but in this country, that will probably restrict you to about half the days of the year, and then you have the problem of night time flying as well (sunset today is before 16:00, and will get earlier yet before the days start to lengthen again).  At present, this is all that a PPL-A allows you to do (I suspect the PPL-D is much the same) - which is why a PPL, without IFR certification, is nothing more than hobby flying, and not something one can ever use for commuting.

The problem is that where I live, we have a population of just under 30,000 people.  The neighbouring town, 5 miles away, which owns the local commercial airport, has a population of 230,000.  That is in excess of 260,000 people living within 5 miles of a commercial airport.  If even 30% of these people own a flying car (I would guess that is about the proportion of people who own a non-flying car), that is around 78,000 flying cars based within 5 miles of a commercial airport.  It only takes 1 of them to venture into the flight path of a commercial airliner on finals, or on takeoff, to cause a major disaster.  It is absolutely imperative to ensure (not merely mandate, but physically ensure) that no fool is going to do exactly that.  It might be reasonable to merely mandate the airspace is kept clear when you are dealing with a mere couple of hundred private pilots, but not when you are dealing with 78,000 of them.

This problem is even worse if one looks at the population within 5 miles of Heathrow airport (one of the commercial airports about 40 miles of me, and depending on whom you listen to, either the busiest, or the third busiest, airport in the world).  The other airport at that distance, Stanstead, is not quite so bad.

Training...do you have a copy of the FARs (CFRs, whatever you want to call 'em) around?  Look in part 61.56a -aka flight reviews (annually, though, not biennials).  That's the key.  I'm not saying 'tis a cure-all, but it'll knock out bad habits that often lead to accidents/incidents (by the way -- something that you might enjoy: CFR 61.153c, eligibility requirements for an ATP rating: "be of good moral character." That appears for no other rating that I've yet looked at.).

Besides this, the absolute minimum training requirement for the sport pilot license is 30 hours of instruction -- that's not that much below what's required for a private license (40 hrs in airplanes)!  Looking at the PTS for sport pilot, I'm thinking that 'tis possible to get folks adequately trained.  The NTSB hasn't released accident data for sport pilots (nothing since 2002, or so I've found, and sport licenses are a fairly recent development), and there isn't much discussion online about it (AOPA, Flying magazine, Google, etc).  Where are you getting your accident data from?

Who's going to pay?  Those who wish to use the system.  Do you have to pay for a driver's license?  No, you don't HAVE to...but you do for the convenience.  This'll cost more, true, but for a greater convenience.  Capitalism!  Not that I'm a fan of the system, but that's what we live in (right now).

Looking at current prices for one of our local flight schools:

http://www.firecrestaviation.co.uk/pricelist.php

I just picked up one at a local airfield, so I cannot say how it compares to others, but it seems plausible.  They suggest that a PPL-A would be about 45 hours, and a package price for 45 hours flight training is about 5K ($10K).  You can understand that this does not fit everbodies pocket.

Besides that, we come back to the problem of visibility.  I got half way through my PPL-A training (about 15 years ago), but finally gave up because for a period of about 3 months, every day I turned up at the airfield for a flight, one look at the weather, and the flight was called off.  I think this has been somewhat mitigated now as last time I visited a flight training school, I was told that when the weather was bad, they simply put students on the flight simulators (just simple PC based things, so I don't know exactly how much use they were, but it kept the money flowing in).

Quite a number of people actually have found it cheaper to fly over to the US, do their entire flight training somewhere in the US where weather is more predictable, and then return to the UK, and do a quick conversion course to convert their US pilots licence to a UK pilots licence.

Either have separable wings (which I can vouch for as being safe...as can every single glider pilot in the world who connects everything properly) or foldup.  My vote's with the detachable option.  Very much with the detachable option.

So, let's see what we have here:

Short range fiberglass/carbon fiber composite electrically powered car that can attach to a set of wings/tail assembly as well as a powerplant (which recharges the car batteries when in operation).  Aircar is then STOVL capable (or VTOL, depending on starting location (air taxi (I'm going to revive the VTOL concept for them, since they're short range only))), is automatically flown to an airway if need be (determined from a preprogrammed destination) and thereby to the destination area where it is landed, unless the area lacks a MLS in which case the PIC will then assume control and land the aircraft (as would also be done in the event of an emergency outside of an MLS).  Car will detach or aircraft will be driven to park (depending on landing location (home or local airfield).

How abouts that?

OK, since you brought up the issue of power out landings, how do you power-out land a VTOL aircraft with fixed wings, and ducted fans.  Cannot be done - you either guarantee no power outs, or you must have a glide path available to a landing strip (possibly in dense urban areas - which is why we are talking about VTOL, and in dense traffic).

I would suggest that in that context, rotary wings would actually be safer (not necessarily the fully articulated wings of a helicopter, but something closer to a gyrocoper, with either passive rotary wings, or simple, non-articulated, powered wings that can quickly switch to autogyration when power fails).

I have already made it quite clear that I think switching to manual control is too much of a liability (maybe OK when you are far away from anywhere, and the only person you can kill is yourself, but not where there is other air traffic around, not even in an emergency).  That means that there should not even be the possibility of switching to manual when a vehicle is entering a high traffic zone.  In reality, I don't think it should be allowed anywhere - not least because even if the PIC is trained and qualified, how do you ensure they retain consistent experience in flying when all the flying (outside of the once in a lifetime emergency) will be on automatic?
 

The Naked Scientists Forum

Flying cars
« Reply #49 on: 25/11/2007 21:22:04 »

 

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