My idea for electric planes instead of high speed rail

Discussion in 'Other Public Transport' started by Technologist, 29 May 2018.

  1. HSTEd

    HSTEd Established Member

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    Honestly I think things like ThyssenKrupp's MULTI are the future - you can make lifts that can act as Personal Rapid Transit!
     
  2. Technologist

    Technologist Member

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    HSTE'd you don't seem to be getting the business model.

    As a passenger you are effectively getting on public transport, the E-VTOL craft can go from one approved and designated place to another via a route that is approved and evaluated for safety. The passenger will not have a method of adjusting where the craft goes.

    Routes can be easily selected so that craft will not be flying over the few places where people stand around outside in any level of density. That may mean that landing pads cannot be that close to certain places but that would not compromise the utility of such a system. The LA system set out by Uber only needed 40 nodes to move millions of people.

    You won't be getting on these craft unsupervised, you won't be allowed to carry anything bigger than hand luggage.

    I reiterate my point airborne weapons are hard, to hit a target you need precision made weapons, bomb sights and precise navigation, even guided weapons require significant operational skill to hit a point target. Even when people are concentrated in a city dropping weapons at random is not particularly effective, the RAF dropped in the region of 7 tonnes of high explosive bombs on Berlin per death on the ground. (Yes I know many people will have been in cellars and bunkers but as I said before I don't think flechettes or debris from a light aircraft will penetrate buildings either.

    Small drones delivering payloads are far more dangerous as is blowing up a train.
     
    Last edited: 19 Jun 2018
  3. Technologist

    Technologist Member

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    This I actually agree with, provided they can get the horizontal speed up to ~15-20mph and come up with some method by which the pod get up to speed off the main route.
     
  4. Technologist

    Technologist Member

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    The noise profile is somewhat different to ground transport, once these things are up at around 100m or so they cease to be audible over the background noise in most cities. Over 1000m and they won't be audible in the countryside.

    It is therefore preferable to ground based transport which is the majority of transport in most cities, an EVTOL in the sky is quieter than being near to a busy road.

    In London Uber was suggesting that the river would be a sensible location to use for landing pads, you can ascend and descend over the water you'd have some of the tall buildings with landing pads on the roof, nobody goes outside on the top of canary wharf. Existing large railway stations also have a noise profile and footprint that EVTOL's could operate in.

    Don't get me wrong, I don't think such a service would fully obsolete the underground, where density is sufficiently great to support digging tunnels the above ground infrastructure is probably close enough packed to make landing difficult unless there is a handy 50 story building nearby.

    It's also worth pointing out that Uber is only estimating that around 10% of journeys in greater LA would be carried out by this method. In all likelihood a new form of transport will really be transformative because it will enable journeys between places that we currently don't think to do because the transport links aren't there.
     
  5. HSTEd

    HSTEd Established Member

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    Good luck doing that in a city that is not like LA (ie. a giant sprawl of suburbia).

    London has people everywhere and most european cities are similar.
    At which point we've built a subway that makes huge amounts of noise and struggles to handle large numbers of people in a compact urban setting (the pads are going to be larger than the surface part of a subway station by some huge margin).

    The whole point of relatively small, independent, load units is you can spread them out to serve more places.

    The listed vertical climb speed is 16m/s, I can't see horizontal speeds much lower than that, which translates to ~35mph or so.
    And the accelerations with linear motors are rather impressive.

    But mainly I am seeing high rises with lots of skybridges.
     
  6. philthetube

    philthetube Established Member

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    Avoiding most of london , birmingham etc then
     
  7. exile

    exile Established Member

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    Two words - energy density. Assuming the electric power is stored in a battery, the weight of any such batteries is going to put a severe limit on the number of passengers that can be carried. The energy density of fossil fuels is much higher than for a battery, and yet air taxis, light planes and helicopters are only used for short distances or by wealthy individuals, and have not proved competitive with mass surface transportation or with cars. The whole thing is a libertarian fantasy.
     
  8. NotATrainspott

    NotATrainspott Established Member

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    I mentioned balconies and roof terraces for a reason. The only way EVTOL craft can become quieter at ground level is to go up, but then the noise just affects new people higher up in buildings. These people are going to be wealthier - indeed, they're probably the clientele for this EVTOL idea in the first place. Would a banker prefer a permanently diminished quality of life just to be able to get from one place to another really quickly? Because of the nature of cities, most EVTOL traffic would end up being people from well outside of the urban area commuting into the city - e.g. a banker in a nice big mansion somewhere in the Cotswolds coming into their City office for work. No one would ever use EVTOL for short distances within development clusters, and development clusters can justify fast underground links to one another. That is, a banker in Canary Wharf is likely to use a future Tube to get to an office in Old Oak Common, because it'll be just as fast in all practicality. Because of that, the utility of EVTOL would be for only a very small number of extremely wealthy people at the cost of making life very much worse for everyone else. It's just a helicopter with an electric motor, with the same problems for society. The technology is really useful and worth developing but it'll only gain widespread acceptance for uses which outweigh the negative impact for the surrounding area - primarily use by the police, search and rescue and ambulance services.
     
  9. Royston Vasey

    Royston Vasey Established Member

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    But but but... an app developer with no IP called Uber says it will work and have done some snazzy renderings to prove it!! ;)
     
  10. Technologist

    Technologist Member

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    You are of course both experts in aviation.....

    It's not just Uber who is working on electric aviation, it's Airbus, Boeing, Rolls-Royce, Siemens. Karem aerospace (previous work was developing the Predator drone) has now designed an E-VTOL which meets Uber's mission requirements with off the shelf batteries available today.

    Two words - acquisition cost, two additional - words maintenance cost.

    Firstly it is perfectly possible to build electric aircraft with useful ranges, aircraft with payload/fuel mass fractions of 85% have been built and flown.

    Even with existing batteries this will allow you to fly many hundreds of km, the reason why the aviation industry is interested in electric flight isn't just the environmental benefits its the economic ones.

    Put simply even if your aircraft is 50% battery because that battery is a commodity item built on an automated production line that battery is cheap.

    For a 20 seater aircraft with 700km clear air range all that is required is a 3.5 tonne battery, this is a $100,000 battery at todays prices. In terms of cost this is basically nothing, you could afford to throw it away every few months. We can then combine this with the fact that motors are very low maintenance as are batteries and power electronics.
     
  11. backontrack

    backontrack Established Member

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    Capacity is a big issue here, surely.
     
  12. Technologist

    Technologist Member

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    Depends, for E-VTOL you can keep on stacking landing pads at a vertiport in a vertical direction, as I've alluded to previously that will get the passengers be hour equivalent to a major station with less footprint than an above ground station. In very dense urban areas you will probably still use undergrounds but they might actually be used as a last mile option for journeys fed from an E-VTOL network connecting suburbs.

    However the original post was about a 20-50 seat regional aircraft replacing high speed rail. Short answer is high speed rail cannot come close, in the UK context a 20-50 seat "Airbus" can cover pretty much any city pair. The sky has essentially unlimited capacity particularly as we are not concentrating all the take offs and landing into a limited number of airports.

    The ground infrastructure isn't that difficult, the aircraft have relatively light weights so Final Approach and Take Off (FATO)'s can be located on roofs of structures. A very high capacity design would have aircraft taking off from multiple levels as well as a ground level usage, for example in Birmingham you could could built it over the top of the wholesale market.

    A worked example would be if we had 20 seat models each FATO would be around 30m square and would have a 60 second interval. Birmingham New Street handles around 15,000 passengers per hour. We would only actually need 12 FATO's to cover this demand.

    That would in theory be an area 120*90m but lets assume it will actually be around 180*120m and that we will be stacking the aircraft vertically during embarkation. We could quite easily fit such a structure on to the the Curzon Street Station area.
     
  13. doa46231

    doa46231 Member

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    It's not just the number of passengers though, it's where they are going.

    An example from Birmingham New Street.

    Take the off peak hour from 12.00 to 12.05.
    In those 5 minutes trains leave serving:-
    Wolverhampton
    Stafford
    Crewe
    Runcorn
    Liverpool South and Lime Street
    Tamworth
    Burton on Trent
    Chesterfield
    Sheffield
    Doncaster
    York
    Darlington
    Newcastle
    Birmingham Airport
    Coventry
    Leamington Spa
    Banbury
    Oxford
    Reading
    Basingstoke
    Winchester
    Southampton Airport
    Southampton
    Bournemouth

    In 5 MINUTES!

    How many 20 seat planes could deal with that in 5 minutes?
    Plus everyone getting on and off in between.

    Also there are 3 local train departures in that time serving many suburban and minor places.
    Would you fly one plane to each place or would three planes hop from one town to the next?
    Or if they just flew to the end town/city, what about the places in between
    To equate the number of passengers using a station and then presume so many planes could take that number, without knowing where they are going is ludicrous.
     
  14. keith1879

    keith1879 Member

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    "Uber's plans are that initially the 4 seat E-VTOLs will be around $1 million but dropping to around $250,000 once the volumes get up to 5,000 per year. My fag packet calculation is that a typical E-VTOL will fly around 3.5 million miles per year, so that is only ~7-29p per mile assuming it lasts 10 years. The most expensive cost will be the pilot, which means that initially the cost per mile will be similar to a taxi as you will have to pay for the pilot's wages however it is split between 4 people and as it moves faster his higher pay is spread over more flights per hour. The eventual cost target once automated is the marginal cost of using a private car around 45 cents per mile. The same economic argument applies when the vehicle is scaled up and the flight is Birmingham to Newcastle." (End of Quote)

    Given that a private aircraft with 8 - 10 passenger seats costs upwards of £5 million I find the estimate of £1 million dropping to £250,000 to be very optimistic. I do recall as a child that we all expected free electricity from Nuclear power .... this looks like an estimate based on the same level of realism.

    if this thread is really intended to cast doubt on the need for HS2 then I can't see that 4 passenger vehicles are relevant at all ..... even if you had 20 passengers in a single craft you would need about 10 of them to give you the same capacity as a half full Pendolino ... so that's 30 an hour to give you anything like the current usage of London to Manchester trains.

    I'm all for thinking outside the box but this doesn't look if it has any realistic chance of even being physically possible for about 25 years - and I think there are serious safety doubts as well. There was a Dan Dare strip in the 1950s which depicted a thing called an Electrosender on the surface of venus ....by comparison that looked practical.
     
  15. keith1879

    keith1879 Member

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    I confess that I can't understand this well enough to deal with the figures in detail .... the weight doesn't look unrealistic however I don't see any mention of the fact that for any given journey there will be an expenditure of energy to lift the vehicle and passengers up to cruising altitude ...... I would expect that to be a significant negative comparison point against a train.

    On the whole I do get the point that (for example) in 1945 there was no expectation that ordinary people would ever fly on a regular basis and yet by 1970 we were happily clambering onto 737s - but somehow this seems to have too much against it - other than as a niche application. It just doesn't look like a mass transportation system - or even a replacement for one.
     
  16. NotATrainspott

    NotATrainspott Established Member

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    You haven't solved the problems. Pure VTOL aircraft have the theoretical advantage of being able to access three-dimensional space easily, going up and down and left and right and forwards and backwards with similar ease. This is what allows you to put the landing sites relatively deep inside three-dimensional urban areas (i.e. considering building heights too). If you're going for larger planes that are going to rely on traditional lift, they're going to have a much harder time taking off and landing. As a result, the amount of three-dimensional urban area that you'd have to hand over to the aircraft operations would get much, much larger.

    Don't think about Birmingham. Think about how on earth you're going to fit this system into the Square Mile, or lower Manhattan, or any of the other areas on this earth rich and important enough to need a system like this. You're never, ever, going to get any sort of system like this past planning authorities. The same areas wealthy enough to benefit from such a system are the ones with the greatest political power to oppose the immense land take and noise it would cause. There's a very good reason City Airport was built on an abandoned dock in an underdeveloped, post-industrial East London rather than in Kensington.

    Again, the idea of the technology is great. Realistically though it's just a mildly cheaper version of a helicopter. They're very useful for certain purposes, but no one over the past 60 years has really found a useful scheduled commercial purpose for them.
     
  17. InterCity:125

    InterCity:125 Member

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    Do we really want our skies full of aircraft though?
     
  18. trash80

    trash80 Established Member

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    The aerial traffic jams in the Star Wars prequel trilogy spring to mind.
     
  19. InterCity:125

    InterCity:125 Member

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    Meaning more wasted power than trains.
     

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