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Offline Nobody's Confidant

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Flying cars
« on: 26/10/2007 14:27:09 »
Will these ever happen? That would be great.


 

another_someone

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« Reply #1 on: 26/10/2007 14:42:30 »
What do you think is great about them, and why do you think they are great?

I am not trying to contradict you, just understand what you think the concept would deliver.

Essentially, as I understand it, a flying car is merely a compact VTOL aeroplane.  Making an aeroplane compact may have advantages, but most people also view the flying car as being something that anybody with a driving licence should be able to fly - but flying is not driving, and the training requirements for pilots are far more stringent than for car drivers (and the spacing of aircraft, and general safety rules, are more stringent - simply because a small bump between cars on the ground might be embarrassing, the same bump at 2,000 feet above the ground would almost certainly be fatal).
 

Offline Nobody's Confidant

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« Reply #2 on: 26/10/2007 17:20:52 »
No more traffic jams at least, and also faster.
 

another_someone

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« Reply #3 on: 26/10/2007 17:57:13 »
No more traffic jams at least, and also faster.

But a massive increase in fatalities due to minor accidents.

Motor cars could go a lot faster, if there were not laws to prohibit it.

Traffic jams would not necessarily be that much easier - you would still have to queue for parking (if 2000 people all want to land on the same roof top at 9 o'clock in the morning, and all leave from the same roof top at 5 o'clock in the evening - you still have a traffic jam).  But, yes, congestion of long distance roads would be alleviated.

On the other hand, how would you deal with traffic separation (i.e. ensuring that traffic moving is different directions are properly separated so they don't collide with each other).  On conventional roads, traffic always stays on the left of the road in the UK (also Japan, and various countries that were part of the British Empire), while staying on the right of the road in the USA and mainland Europe - but if there are no roads, then what is the left and right hand side of the road?  Commercial airliners travelling in different directions are separated by 500 feet vertical separation, and travelling in the same direction, are generally about 3 minutes behind each other - this is considerably greater separation than most cars have.

There are also problems with VTOL aircraft that they should not be directly beneath each other lest the downthrust of the upper aircraft force down the lower aircraft - in the early days, a few helicopters crashed when they were flying in tight formation because the lower helicopter got caught in the downthrust of the upper helicopter.
 

lyner

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« Reply #4 on: 27/10/2007 22:37:44 »
I don't want one flying over MY house, thanks.
Cars on a well defined road are a big enough menace without bringing the menace onto my roof.
Much more expensive  for fuel , too.
Possibly attractive if they were controlled automatically - but traffic density  and average speeds on roads would be much better with totally automatic control, in any case. Takes the dozy human operator out of the equation.
 

another_someone

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« Reply #5 on: 28/10/2007 03:36:36 »
I don't want one flying over MY house, thanks.
Cars on a well defined road are a big enough menace without bringing the menace onto my roof.
Much more expensive  for fuel , too.
Possibly attractive if they were controlled automatically - but traffic density  and average speeds on roads would be much better with totally automatic control, in any case. Takes the dozy human operator out of the equation.

I do agree that driverless cars are definitely the way to go.

On the other hand, I am not totally convinced about your fuel economy argument.  There are clearly trade-offs, but there is much debate about whether flying is that inefficient when measured in passenger miles (ofcourse, when measured in passenger hours, it is a different matter).  After all, one form of flying machine that bridges the gap are maglev trains, and although they have yet to come into their own, there are many who do regard the advantages outweigh the difficulties in having a train that flies, even if only a few inches off the ground.  The real problem with flight, in energy costs, is the large expenditure of energy when going nowhere (it makes the fuel cost of waiting at traffic lights for terrestrial vehicles seem quite cheap).

The calculations become even more complex when you include the environmental, material, and energy costs involved in laying roads (costs that are far lower for building airports - especially if one removes the need for most of the terminal buildings, and lower yet if one looks at landing and takeoff facilities for VTOL flight).

My major concern still remains the safety aspects, and possibly amenity to light (bad enough when you have a major motorway built outside of your house - but when you have a traffic jam 2,000 feet or more high in front of your house, it could make a substantial difference to your quality of life).  Even the issue of noise - even if you make the vehicles fairly quite, if you have thousands of them close together, the cumulative effect is still significant, and noise from 2,000 feet up will generally carry further than noise from lower altitude (although at least you don't need to deal with tyre rumble).
« Last Edit: 28/10/2007 03:44:38 by another_someone »
 

lyner

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« Reply #6 on: 28/10/2007 16:20:47 »
Can there really be any doubt about the inefficiency of keeping objects suspended in the air, using reaction / wings - fixed or rotating compared with a car waiting with its handbrake on then moving when it needs to?
S/VTOL consumes a lot of fuel and you would need that, if you were to avoid making the end bits of your journey by road, in any case.
Flying to work or to visit friends would be suitable for people living in the outback or similar. Those who can afford to do it, already run light aircraft.
When the antigrav unit is for sale in B&Q, I will bolt one to my car.
 

another_someone

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« Reply #7 on: 28/10/2007 18:52:55 »
Can there really be any doubt about the inefficiency of keeping objects suspended in the air, using reaction / wings - fixed or rotating compared with a car waiting with its handbrake on then moving when it needs to?

I did acknowledge the problems with aircraft that are having to wait.

There is no question that keeping an aircraft in the air costs energy, but on the other hand there are savings in energy in not having to contend with rolling resistance, and not having to cross varying terrain (whether it is climbing hills, or just going across speed bumps and pot holes), and very possibly better drag coefficient (bearing in mind that motor cars still produce both lift and drag, albeit it is mostly intended that the lift should be negative).  The big issue is, as you point out, there is no need to produce lift or drag when a terrestrial vehicle is stationary.  On the other hand, modern air traffic control attempts to ensure that when an aircraft takes off, its entire flight timetable is already planned, right to the point of landing, so as to minimise the likelihood of their being any delays along the route (the delays occur before takeoff, when there is little impact on fuel consumption).  If vehicles are totally under automated control (whether air or terrestrial vehicles) then there is no reason why similar traffic management systems could not be in place to reduce the inefficiencies of having to insert delays into the journey.

And, as I mentioned, you also need to fact in the energy costs involved in building and maintaining roads.

So I do not doubt that there are energy costs in flight, the question is how do those compare with the various specific energy costs involved in terrestrial transport?
 

lyner

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Flying cars
« Reply #8 on: 29/10/2007 23:17:29 »
I would need detailed figures to convince me that an airborne system could ,in any way  ,be cheaper than a ground based system. The cost of the extremely high level of maintenance needed for all those flying machines would, surely, outweigh the cost of mending roads. (They even replace the oil after every flight, on military aircraft, I believe!)
And where are these things going to land? On the roof? What about for a block of flats? The top floors would all have to be multi-story  aeroplane parks. Who would want a penthouse apartment if you were in the middle of everyone coming and going - plus pollution?
 

another_someone

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« Reply #9 on: 30/10/2007 03:46:19 »
They even replace the oil after every flight, on military aircraft, I believe!

I cannot see that comparison with military vehicles is really valid (we are not talking about aircraft that are expected to be flying at Mach 2, or undertaking any of the rigorous punishment of a combat vehicle).

I did not disagree with many of the other logistic issues of short distance air transport, I was only really suggesting that the cost factor itself is far more complex, not least because you have to take account of the entire infrastructure cost.

I do think that any transport system that can remove the need to build and maintain roads (even rail roads) has a lot to be said for it (but running a 3 dimensional transport network, rather than a 2 dimensional one, would present more problems, as you point out, not least with the bottlenecks for landing and takeoff facilities).

One can add, if one wants to significantly reduce the cost of flight (at least, at low speed), then one can probably best do that with lighter than air vehicles (although these are scarcely compact).
« Last Edit: 30/10/2007 04:39:48 by another_someone »
 

lyner

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« Reply #10 on: 30/10/2007 11:58:21 »
The whole thing about personal 'air cars' smacks too much of early Science fiction films - Fritz Lang, and the like.  Very attractive, at first sight, but a bottomless pit of potential expense and hazards.
If you think an extra dimension would help, then let's have a lot more fly-overs and underpasses. I could even contemplate a 'leap-frogging' system to get across busy highways. (Har har)
I just couldn't trust Joe public in the air space above my head. At least I can choose to walk on the pavement and avoid road traffic.
 

another_someone

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« Reply #11 on: 30/10/2007 14:07:38 »
The whole thing about personal 'air cars' smacks too much of early Science fiction films

Agreed - and that my explain their popular appeal, but is neither an argument for or against them in practical terms.

If you think an extra dimension would help, then let's have a lot more fly-overs and underpasses.

The key point is that these do not create a 3 dimensional space, but rather simply a more convoluted 2 dimensional space (which is why they avoid the traffic management, and associated safety implications, of having to deal with a true 3 dimensional space).

I just couldn't trust Joe public in the air space above my head. At least I can choose to walk on the pavement and avoid road traffic.

Agreed totally - which is why, even to contemplate the notion, pilotless/driverless vehicles would to my mind have to be a prerequisite (although not necessarily a sufficiency).
 

lyner

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« Reply #12 on: 30/10/2007 15:06:29 »
I could stick my neck out and say "not in my lifetime".
There's a challenge.
 

Offline nikomaster

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« Reply #13 on: 04/11/2007 09:46:31 »
Yes it would be great, is not difficult we must defeat the gravity sistem, today air let us fly, maybe later we can find a better system for that, maybe not.
Lets stay at ground.
 

lyner

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« Reply #14 on: 04/11/2007 11:12:16 »
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is not difficult we must defeat the gravity sistem
??????????? I beg to differ.
You are going to need a totally different system of Science, right from square one. And would that not rather clash  with the  one we've got already?
This site is called the Naked Scientist - not  the Naked Magician.
 

Offline nikomaster

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« Reply #15 on: 04/11/2007 12:04:14 »
I am not talking about Magic, if i am talking about defeating the gravity i am saying it to do it with technology not with magic. We defeat gravity with aircrafts, is that magic?, NO that is no magic, is technology ,the air that pass throught the winds arise the aicrafts, so we can do the same with cars, but on a city using a car that expulses air at 100 mph just for flying and another 30 cars on the same street doing the same will be anoying and dangerous for people walking on the streets.
 

lyner

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« Reply #16 on: 04/11/2007 17:53:45 »
If I stand up, I am defeating gravity- that's obvious.
An aeroplane is another way of doing it too - but it is neither a new idea  nor practical for my rooftop.  So far, all ways of lifting an air vehicle depend on 'reaction' - pushing air down or backwards to provide lift.
You, also, seem to reject that as an idea (reasonably enough) so what technology did you have in mind?
It would be 'nice' if it could be done but how?
Without some reasonable Science or Technology it becomes Magic.
 

another_someone

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« Reply #17 on: 04/11/2007 18:55:07 »
If I stand up, I am defeating gravity- that's obvious.
An aeroplane is another way of doing it too - but it is neither a new idea  nor practical for my rooftop.  So far, all ways of lifting an air vehicle depend on 'reaction' - pushing air down or backwards to provide lift.
You, also, seem to reject that as an idea (reasonably enough) so what technology did you have in mind?
It would be 'nice' if it could be done but how?
Without some reasonable Science or Technology it becomes Magic.

I think I already mentioned lighter than air flight (displacement rather than reaction).

Magnetic or electrical reaction is another option.  This works in one dimension, when a objects are suspended above or below a metal rail, and travel along a vector parallel to that rail; but could be a bit more problematic trying to manage objects travelling is many layers above/below the rail (or surface) and travelling in many different vectors (plausibly possible to do, but very complex to calculate the fields required).

Other options would be (as you have indicated) simply to walk upright, on very long legs (again, there would be some problems in ensuring the legs of various vehicles don't get entangled - or alternatively, have one vehicle walk upon the tops of lower vehicles).
 

Offline nikomaster

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« Reply #18 on: 05/11/2007 01:41:36 »
Here we go again with "Magic" i repeating my self? i am just telling one of the ways
 

another_someone

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« Reply #19 on: 05/11/2007 02:31:27 »
Here we go again with "Magic" i repeating my self? i am just telling one of the ways

What are you talking about 'magic' - who is talking about 'magic'?

What possible ways are you referring to?
 

Offline Alandriel

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« Reply #20 on: 05/11/2007 09:35:19 »
ahhh but the technology already exists - no magic. See for yourself



... marvel at the electro magnetic field that floats the car...



....it just might be a bit tricky though applying that in large scale  ;) ;D


The thought of driver-less systems is just as scary though - totally at the mercy of technology; not a very happy thought for me at all...
 

another_someone

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« Reply #21 on: 05/11/2007 11:18:12 »
The thought of driver-less systems is just as scary though - totally at the mercy of technology; not a very happy thought for me at all...

So you would never fly in an Airbus A320 (and ever more newer aircraft from all the major producers).  The pilot may have some control over the aircraft, but it did not stop one of the pre-production models from crashing at a French airshow because the computers decided to lower the landing gear and configure for landing when all the pilot wanted was to perform a low level fly past.

Even aside from issues of fly by wire, you still depend on lots of electronics for navigation, and in poor weather, the plane is likely to land with almost no visual input from the pilot at all, so the pilot is totally dependent upon the MLS technology telling him where the runway is, and if the system gets it wrong, then the pilot is unlikely to recover the situation.

But then, is system error really so much less likely than human error?
 

lyner

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« Reply #22 on: 05/11/2007 18:01:15 »
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So you would never fly in an Airbus A320
but an Airbus costs a fortune to maintain - well out of the range for joe public to afford for his runabout. The comparison is not really valid.
 

Offline Alandriel

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« Reply #23 on: 05/11/2007 21:12:47 »

If you put it like that GeorgeÖÖ.I canít argue with you. ;D

Itís ALL scary LOL. - Perhaps a little of my control-freak-ishness is shining through here but despite all the logic Iím actually less comfortable if all human control is dropped.
Machines/systems are overall statistically probably less error prone than humans but there is something inherently more satisfying  if in the end one can blame a human rather than a machine.
I donít knowÖ. perhaps all my warped thinking is coloured by too many silly sci-fi thrillers (the machines take over a la terminator, matrix etc) or Iím simply an even bigger control freak than I assumed so far. ::)
 

another_someone

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« Reply #24 on: 05/11/2007 21:29:27 »

If you put it like that George…….I can’t argue with you. ;D

It’s ALL scary LOL. - Perhaps a little of my control-freak-ishness is shining through here but despite all the logic I’m actually less comfortable if all human control is dropped.
Machines/systems are overall statistically probably less error prone than humans but there is something inherently more satisfying  if in the end one can blame a human rather than a machine.
I don’t know…. perhaps all my warped thinking is coloured by too many silly sci-fi thrillers (the machines take over a la terminator, matrix etc) or I’m simply an even bigger control freak than I assumed so far. ::)


I too am a control freak, but if I cannot control something myself, which is why I hate public transport :), but I take no pleasure in blaming human or machine - I would rather not have anything to blame them for than to choose someone to blame.

But even today, much of what you believe you control is mediated by machines; from most of our financial transactions, to automatic washing machines (or do you wash by hand?), to  automatically opening doors.

With regard to driverless cars, when was the last time you were in a lift that was operated by a lift boy - is that not a driverless car of sorts (you punch in the destination, and it automatically takes you there - except that the destination is not a street address but a floor within a building)?  In fact, the Docklands Light Railway is a railway system that runs totally without drivers (although I doubt the passengers consider it any differently to the London Underground, that does have a nominal driver).
« Last Edit: 05/11/2007 21:32:36 by another_someone »
 

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