[k8 (OP)]

katie asked the Naked Scientists:
   
I like the CD hovercraft experiment.

I was wondering - is it possible to transport ourselves by hovercraft on land as well as sea?

Would it be possible to use this technology in a sustainable way in the future and save using roads too?

What do you think?

[imatfaal]

Katie

Yes We Can! 

http://www.youtube.com/results?search_type=search_videos&search_query=Hovercraft+Racing+at+Troy+Ohio+in+2003+&search_sort=relevance&search_category=0&page=

I doubt it's very energy efficient though

[graham.d]

Actually they probably compare OK with other transport modes on efficiency. The problems would be noise and safety. They are VERY noisy. Because of the lack of friction with the surface below them, changing direction is not very precise and they have a tendancy to be blown sideways in a strong crosswind. Roads full of hovercraft would be like being on a dodgem track. They are fine on open flat spaces but not so good if the terrain has large bumps though. At sea they can't be used if the wave height is too high. Crossing rough land could be problematic. 

[imatfaal]

Graham - are you sure of the efficiency.  Just using some facts grabbed from net and rough calcs

http://www.wright-international.com/wil2208-hovercraft.php

fuel tank 8000 litres - enough for 8 hours max. At 45kts this is roughly 414 miles using 1760 gallons transporting 100 passengers.  this is an at sea figure because I cannot find any commercial figures for on land


http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation

whereas two consumer buses (55 passngers each) would this 414 miles using only about 115 gallons between them.

I realise that the diesel engine and road transport has undergone enormous research to increase fuel efficiency which the hovercraft has not - but still...

[graham.d]

I wasn't comparing them with buses but I think you are right that they are generally not as efficient as road vehicles. I was thinking of smaller units like these...

http://www.hovercraft.com/content/index.php?main_page=index&cPath=1_79_111

They can do about 16 mpg with 6 passengers. Not very good but comparable (very roughly) to a car. Some (other makes) very small units which just have a 250cc motor bike engine are quite fast, but I didn't see any fuel consumption figures.

[Geezer]

Hovercraft are probably much more efficient than any other vehicle if you want to travel over waterlogged land because a hovercraft might be the only vehicle that won't get stuck.

Efficiency can be a difficult thing to measure.

[daveshorts]

To exert a force the hovercraft has to push lots of air backwards, which takes a lot of energy. This is not too bad on flat roads, as the hovercraft only has to exert a force to start or stop moving, and the low friction is an advantage, however as soon as you hit a steep slope, you have to exert a very large force all the time, just to avoid falling back down the hill. In a car you can just change down and it is almost as efficient as going on the flat, but in a hovercraft you have to push a stupid amount of air backwards even if you are standing still. and for this reason most hovercraft can't climb much of a slope.

[tommya300]

katie asked the Naked Scientists:
I like the CD hovercraft experiment.
I was wondering - is it possible to transport ourselves by hovercraft on land as well as sea?
Would it be possible to use this technology in a sustainable way in the future and save using roads too?
What do you think?

Yep it is an amphibian ATV with limits and with no ground base drivetrain (no wheels)
Major Down side  [8][B)] on land it raised debris that can injure. Not safe.
In the USA, DMV requires a stable ground touch system.
Since it is a very low altitude flying machine, it does not qualify with certain DMV rules, nor with certain aviation rules.
Consider it an Outlaw ATV. [xx(]
Never to reach the legal standards.
But it might qualify as a hyperhydroplain sea craft, a sort of a sail boat
 

[k8 (OP)]

thanks for the info- found it interesting to read.....
looking at the youtube sites that you/imatfaal signposted me to like

and the racing ones,the hovercrafting on land looks excellent to do!

though brought down to earth so to speak by the other also fair points
i would think that much could be done about fuel efficiency to improve it even more?
 and to deal with debris too?
however, the going up hills and over bumps though i'm not so sure how possible to improve that would be?

(...not to mention the possibility of the US changing their rules.......... ; ) only kidding ; ) if it was good and safe enough, so there was money to be made, they probably would? ; ) plus imatfaals link looks like the already use this kind of transport in some cases......

and the link that you/graham d posted makes me wish for a hovercraft ; ) and on their site it says the noise reduction the company seems to be working on e.g. 'We use large diameter slow turning propellers that generate very low levels of noise.' and for the fan 'This slow rpm keeps the noise to a minimum while providing an excess of lift air.' 
 ....and they can even tow things too!....hover carvans perhaps ; ) !

i was thinking that we see in science fiction movies flying cars, but hovercars lower to the ground could be good, especially as potentially it could reduce the amount of paved road surfaces..... hovercrafting over grass etc like they do in the videos looked good = more oxygen for us ; ) (and nicer looking places perhaps!)

 i didn't realise they could carry so much too, like on the military site you/imatfaal posted that says
"This amphibious Hovercraft has been designed to facilitate either a payload of 20 Tonnes of equipment or up to 100 Troops to be deployed where conventional craft cannot operate." !
 as well as the smaller ones that graham posted about that hold 6 people yet is comparable to the car in fuel.

think it's a good point that geezer says about rating efficiency- and the ability to move over land that cars couldn't would be a bonus too....how about over snow too?

i remember now seeing a pretty good hovercraft skateboard on a kids program that builds things that kids invent/suggest through drawings- though technology could do with a little future improving, but it was pretty good starter and made at a low price i think....

 so do you think that perhaps, with a little more research and development, there is a similar technology possibility for the future?

[imatfaal]

Wheels on an axle is such a neat and simple technology that it will take some beating.  I would much rather be in a car or conventional boat that loses power than a hovercraft!  the amphibious nature of hovercraft is its selling point as we can already create more efficient a/o faster cars on land and more/efficient a/o boats in the water; I struggle to think of a mass market application that prefers amphibiousness over efficiency or speed