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RK890
24-Feb-10, 07:07 PM
Hi all (new here so don't disregard me yet)

i'm involved in the racing of electric vehicles, and was wondering if a hovercraft could be built using an electric motor and 2 lead acid batteries. The motor i'm considering has a tourque of 2.2Nm and a relativley low speed of 1750 RPM (yes, i can gear this up but wondering about weight issues.....)
What i want to know is this: Is it even possible? The motor and batteries alone weigh 20 Kg!

Many preemtive thanks

Rob (RK890)

broad5186
24-Feb-10, 07:32 PM
Hi Rob

i think you may be able to get a hovering board, like the ones made with 2Hp leaf blowers but as for a complete craft i think you may struggle, i think there are some craft that can just about hover and carry a person with about 12Hp, a lot of cruising craft use 5Hp lift engines just to hover

just my opinion

Tony

curtis5420
24-Feb-10, 07:44 PM
Hi all (new here so don't disregard me yet)

i'm involved in the racing of electric vehicles, and was wondering if a hovercraft could be built using an electric motor and 2 lead acid batteries. The motor i'm considering has a tourque of 2.2Nm and a relativley low speed of 1750 RPM (yes, i can gear this up but wondering about weight issues.....)
What i want to know is this: Is it even possible? The motor and batteries alone weigh 20 Kg!

Many preemtive thanks

Rob (RK890)

are you talking about a model hovercraft?

Ian Brooks
24-Feb-10, 07:45 PM
Electric hovercraft would be easy if you could plug them in!

It's about energy... a 100 amp-hour battery contains about 36kJ of energy. 1 gallon of petrol contains 134000kJ. The most efficient cruising craft will consume about 1.5 gallons per hour. To hover for one hour using batteries, you need 5583 100 Ahr batteries!

So unless you've got a ling, long mains lead you arn't going far.

HOWEVER.... if you're interest is in producing a demonstration vehicle, more of an academic exercise, then it could be done. Look for the human-powered hovercraft on the web, and take your inspiration from them.

http://steamboatwilly.org/

Ian

Ewan Black
24-Feb-10, 09:27 PM
Electric hovercraft would be easy if you could plug them in!

It's about energy... a 100 amp-hour battery contains about 36kJ of energy. 1 gallon of petrol contains 134000kJ. The most efficient cruising craft will consume about 1.5 gallons per hour. To hover for one hour using batteries, you need 5583 100 Ahr batteries!

So unless you've got a ling, long mains lead you arn't going far.

HOWEVER.... if you're interest is in producing a demonstration vehicle, more of an academic exercise, then it could be done. Look for the human-powered hovercraft on the web, and take your inspiration from them.

http://steamboatwilly.org/

Ian

OR and on-board generator- it Worked for the Top Gear battery car :D

atters
25-Feb-10, 06:06 AM
There was a guy over here a couple of years back who was looking into hoverising a golf-cart using the main drive motor for thrust and a 12HP lift engine modified to also generate the power for the thrust motor. I have heard nothing from him in years and I guess it fell flat.

Maybe its a bit on the impossible side with our current technology available, batteries are getting better every year and motors are getting stronger and using less power. Maybe in a few years it is a viable option, could make F2 and F503 a lot quieter. :rolleyes: (go on boys, have a go at me, I deserve it). :D

Hovertrekker
25-Feb-10, 12:01 PM
Bob Windt has been making them. Powered by 3 lead acid batteries and 36v motors. Take a look.
472YyTVQYCo

Ewan Black
25-Feb-10, 03:18 PM
That's one talented dog!

SPELEO
30-Aug-10, 09:08 AM
Hang on -- there are a number of electric aeroplanes flying today (see http://www.yuneec.co.uk/ for example), so surely hovercraft are feasible -- and would have about twice the endurance of an aeroplane for the same size batteries?

Battery weight less of an issue, in any case.

Al
30-Aug-10, 11:22 AM
I don't know much about electric motors, but surely the motor is used to drive the lift/thrust fan/s, so why cant these fans incororate some sort of turbine to generate power to help charge the batteries? I know its not possible to get perpetual motion, but thinking it must be possible for the batteries to have some charge put into them while the craft is running to give a longer running time. I'm sure there will be some reason why this is not possible with current technology, but just a thought.:)

SPELEO
30-Aug-10, 03:22 PM
To get 10 watts of power out you'd need to put 11-12 watts in. So a net loss from the battery ...

LittlePaul
31-Aug-10, 02:55 PM
FYI, as an aside, the current competition rules prohibit electric motors from racing craft...

Bill Baker
2-Sep-10, 08:53 AM
Bob Windt has been making them. Powered by 3 lead acid batteries and 36v motors. Take a look.
472YyTVQYCo

Some guarding for the dog might be nice?

Ewan Black
2-Sep-10, 08:54 PM
Some guarding for the dog might be nice?

what? like this? http://www.fordogtrainers.com/ProductImages/pictures/breed/german-shepherd-dog/dog-muzzles/leather-dog-muzzles/agitation-dog-muzzle-dondi/leather-dog-muzzle-padded-agitation-attack-police-schutzhund-k9-service.jpg
(http://www.fordogtrainers.com/ProductImages/pictures/breed/german-shepherd-dog/dog-muzzles/leather-dog-muzzles/agitation-dog-muzzle-dondi/leather-dog-muzzle-padded-agitation-attack-police-schutzhund-k9-service.jpg)

Brian G. Reynolds
2-Sep-10, 08:57 PM
Those things are so cruel!

Stopping a dog from breathing and stopping it from doing what it does best... i.e. biting people!

B.

LittlePaul
3-Sep-10, 12:05 PM
what? like this? http://www.fordogtrainers.com/ProductImages/pictures/breed/german-shepherd-dog/dog-muzzles/leather-dog-muzzles/agitation-dog-muzzle-dondi/leather-dog-muzzle-padded-agitation-attack-police-schutzhund-k9-service.jpg
(http://www.fordogtrainers.com/ProductImages/pictures/breed/german-shepherd-dog/dog-muzzles/leather-dog-muzzles/agitation-dog-muzzle-dondi/leather-dog-muzzle-padded-agitation-attack-police-schutzhund-k9-service.jpg)


Or maybe like this? http://www.police.govt.nz/sites/default/files/dogs_and_handlers.jpg

Ewan Black
3-Sep-10, 07:55 PM
Or maybe like this? http://www.police.govt.nz/sites/default/files/dogs_and_handlers.jpg

Do you think the bloke on the right had any ida how camp he'd look when this pic was taken:D

Jason Mayo
14-Sep-11, 07:35 PM
Electric would certainly have to have a formula of its own. With current technology you could fit a 40hp motor to a light hovercraft and power it for about 15 mins using lithium ion batteries whilst still being light enough to hover and endure a 6 lap race. It would be an expensive pursuit at today's prices, about 3000 to kit out for electric I think, and 3 hours charge time before you are good for the next heat. But it's bleeding edge technology which of course makes it all the more attractive.

Ewan Black
14-Sep-11, 08:21 PM
it's bleeding edge technology which of course makes it all the more attractive.

It's bleeding expensive technology!!!!

Winst
14-Sep-11, 08:56 PM
and 3 hours charge time
How would we charge them in the middle of a field? Generator? = massive fuel costs so might as well have a petol engine.
Don't think Charlie or Jake would like having hovercraft parked outside thier house draining thier electricity supply especially at todays cost!!!

keates5632
14-Sep-11, 10:38 PM
Forgive me foolishness (but it is something i do well) but i thought the whole point of a hovercraft was that it was capable of going on land and water and other random surfaces.
I was also led to believe that water and electricity were not a good mix...

Jason Mayo
15-Sep-11, 10:21 AM
It would be great if we could focus the thread on a possible future formula for electric racing, just like there is for other Motorsports. It would be great if this thread could be used to discuss any recent developments in battery and motor technology that might inspire some of us to develop suitable craft.
So far there seems to be a slight lack of positive discussion here.

Winst
15-Sep-11, 10:38 AM
So far there seems to be a slight lack of positive discussion here.
Question

How would we charge them in the middle of a field? Generator?
Some other source?
Solar enegry?

Discuss......

Jason Mayo
15-Sep-11, 10:59 AM
No a wind turbine driven by the back draught of another hovercraft ;)
Seriously though, I think power source for charging is not really an issue here, nor is overall efficiency of conversion from petrol (generator) to electric or coal/nuclear (Jake or Charlie's socket).

Nick Drew
15-Sep-11, 11:47 AM
I have an article waiting to go in the magazine from a guy who built an electric powered hovercraft. To be fair it only hovers as it doesn't have a thrust fan, but the principle is proven. Keep an eye on your doormat ;)

Nick

Jason Mayo
15-Sep-11, 01:08 PM
An interesting aviation company worth checking out.
http://www.yuneec.com/

wcastendijk
15-Sep-11, 02:27 PM
You can't expect it to work over night.
Nicolaus Otto invented the internal combustion "Otto" engine in 1876 but got it to work on a motorbike 8 years later in 1884 (sortof). A bit later, say 1984 we are trying to get it better, like more economic.
Benoit Raynal (a GP in France) is building a fully functioning electric craft as we speak in his garage. I think it will work! Goal is 25kmh for 1,5 hour till re-charge. I'll wait a year and think it will be in the LH magazine ! AND . . . if the club is still there, we'll be hovering with maybe Nukefiusion in 100 years. :)

Jon Pert
15-Sep-11, 04:21 PM
AND . . . if the club is still there, we'll be hovering with maybe Nukefiusion in 100 years. :)

Nah, still be using TZR's! http://www.jonrb.com/emoticons/hehe.gif

datkins
15-Sep-11, 05:08 PM
Jason,

What's the power train your thinking of. looked into this some of the electric TT stuff and 3K would cheap compared to what I found! Input required,

Prickle,

to make the water electric issue even more interesting the electric TT's have water cooled electric motors so you don't need to get onto(into) the water to mix it up, can't be much worse than an electric kettle can it.....

Jason Mayo
15-Sep-11, 09:16 PM
Jason,

What's the power train your thinking of. looked into this some of the electric TT stuff and 3K would cheap compared to what I found! Input required,

Im still trying to get prices and availability from these people but the power systems that yuneec are doing for their airplanes look interesting, 40kw (54hp) weighing in at 19kg and draw nearly 300amps at maximum. They rotate at 2,400 rpm which should negate the need for gearing, therefore the motor could be mounted direct onto the thrust fan. The downside is the battery pack which weighs 87 kg and I think would last about 20 minutes at full throttle. You may need a spare one of these. I'm not sure how much a 503 weighs with exhaust, gears and 20 mins of fuel but it is not much less than an electric set up. The 3k that I quoted was from a US company selling electric marine motors, but the rpms were much higher.

Jason Mayo
15-Sep-11, 09:27 PM
to make the water electric issue even more interesting the electric TT's have water cooled electric motors so you don't need to get onto(into) the water to mix it up, can't be much worse than an electric kettle can it.....
I don't think this is a prohibitive problem but never the less one that shouldn't be overlooked.
The supply to a 40kw motor is 133volts AC, because the motor is brushless it uses alternating current which is more shocking than the relatively harmless 12v DC. Electrical safety would need to be considered whether on land or water.

datkins
15-Sep-11, 09:32 PM
So does that include the battery? they seem to be $1000 a pack and 4 volts so you need a few..... might have that wrong though

david


Im still trying to get prices and availability from these people but the power systems that yuneec are doing for their airplanes look interesting, 40kw (54hp) weighing in at 19kg and draw nearly 300amps at maximum. They rotate at 2,400 rpm which should negate the need for gearing, therefore the motor could be mounted direct onto the thrust fan. The downside is the battery pack which weighs 87 kg and I think would last about 20 minutes at full throttle. You may need a spare one of these. I'm not sure how much a 503 weighs with exhaust, gears and 20 mins of fuel but it is not much less than an electric set up. The 3k that I quoted was from a US company selling electric marine motors, but the rpms were much higher.

Paul Fitz
15-Sep-11, 10:08 PM
Seriously though, I think power source for charging is not really an issue here, nor is overall efficiency of conversion from petrol (generator) to electric or coal/nuclear (Jake or Charlie's socket).

Hovercraft are simply too inefficient to be electrically driven in practice. Using existing fans etc. even an ultralight, practical craft for a small child would require about 2.5 Hp for lift and minimal thrust (i.e 1.9Kw) which converts to 1.9 KJoules/second. As Ian has already pointed out there are no batteries available which could provide this amount of energy for long enough to race.

It is probably a cruel twist of fate to the green lobby that hovercraft are less efficient the smaller they become :o) You might get one to hover on Ice or glass for a minute or two, but racing?.. not in our lifetime.

The harbinger of doom

Perhaps I should have added...
Obtaining thrust from an electric motor is not the problem. a reasonable (practicable) amount of thrust can be generated with 1/4 - 1/3 Kw. The problem will be generating the pressure required for lift.

Jason Mayo
15-Sep-11, 10:22 PM
Yes, lithium ion batteries are quite expensive at the moment. The prices will have to come down quite a bit before I start building one. At today's prices, min 500 per kwh, you would need to spend 5000 to achieve 40kw for 15mins. Might need a generous sponsorship deal.

wcastendijk
15-Sep-11, 10:31 PM
people are working on it.

http://www.hovercraft.com/content/index.php?main_page=index&cPath=30_247

Give it time or join the effort.

Wouter



Hovercraft are simply too inefficient to be electrically driven in practice. Using existing fans etc. even an ultralight, practical craft for a small child would require about 2.5 Hp for lift and minimal thrust (i.e 1.9Kw) which converts to 1.9 KJoules/second. As Ian has already pointed out there are no batteries available which could provide this amount of energy for long enough to race.

It is probably a cruel twist of fate to the green lobby that hovercraft are less efficient the smaller they become :o) You might get one to hover on Ice or glass for a minute or two, but racing?.. not in our lifetime.

The harbinger of doom

Perhaps I should have added...
Obtaining thrust from an electric motor is not the problem. a reasonable (practicable) amount of thrust can be generated with 1/4 - 1/3 Kw. The problem will be generating the pressure required for lift.

Jason Mayo
15-Sep-11, 10:46 PM
there are no batteries available which could provide this amount of energy for long enough to race.

Ignoring cost for the moment, there is a battery capable of providing enough power.
Lithium ion batteries store about 116Wh/kg which is 464W for 15 minutes per kg. therefore to supply 40kw your battery pack would weigh about 80kg. Together with a motor your total engine payload is 100kg. Surely this could fly long enough to race.

datkins
16-Sep-11, 05:21 AM
Well as a novice at the moment my venoms tank has at least half a litre left after a ten minute race so might not even need that much! should be a gain on efficiency of direct drive, and no-one would hear you coming ......... would we be able to doa direct KW - HP calculation to allow a craft to enter a race formula? 40KW is around 50HP so F3/503 approx equivalent.

Paul, What's the concern over pressure, I'm not familiar enough with the maths, had assumed that if you had the power then its matter of rpm and pitch on the fan to get plenum/skirt pressure right

David


Ignoring cost for the moment, there is a battery capable of providing enough power.
Lithium ion batteries store about 116Wh/kg which is 464W for 15 minutes per kg. therefore to supply 40kw your battery pack would weigh about 80kg. Together with a motor your total engine payload is 100kg. Surely this could fly long enough to race.

datkins
16-Sep-11, 05:25 AM
Example bike, lapped TT at just under 98mph,

http://motoczysz.com/motorcycles/e1pc_2010


Ignoring cost for the moment, there is a battery capable of providing enough power.
Lithium ion batteries store about 116Wh/kg which is 464W for 15 minutes per kg. therefore to supply 40kw your battery pack would weigh about 80kg. Together with a motor your total engine payload is 100kg. Surely this could fly long enough to race.

Al
16-Sep-11, 11:22 AM
I think the question that should be looked into is how do we make hovercraft more energy efficent?

This would mean a total rethink of how hovercraft are built. You can make anything hover if you chuck enough power at it, but it is time to move away from this mentality and start thinking outside the box.

Jason Mayo
16-Sep-11, 03:08 PM
I think the question that should be looked into is how do we make hovercraft more energy efficent?

This would mean a total rethink of how hovercraft are built. You can make anything hover if you chuck enough power at it, but it is time to move away from this mentality and start thinking outside the box.

In a straight line the hovercraft is quite an efficient vehicle, but with racing every turn has to be earned from the pure thrust that the craft has available. Is there a different approach that I have overlooked here?

Al
16-Sep-11, 05:09 PM
In an integrated craft there is a massive energy drain/waste just to get lift I seem to recall somewhere near 50% wasted energy. There has to be a better way, but I haven't got a clue how. Maybe look at a dyson vacuum cleaner by creating a cyclone the energy is increased, maybe the principle could be applied to a hovercraft some how.

lyne0990
16-Sep-11, 05:52 PM
We visited Owen Ellis when we were in Australia, and he is well down the research road for electric power, perhaps starting with a lift engine.

Jim Lyne

Jason Mayo
16-Sep-11, 05:52 PM
Perhaps electric could benefit from having multiple lift fans around the perimeter of the craft rather than one big one at the front. Electric hovercraft could also utilise reverse thrust, which would not work with an integrated single engine approach.

Al
16-Sep-11, 07:28 PM
Perhaps electric could benefit from having multiple lift fans around the perimeter of the craft rather than one big one at the front. Electric hovercraft could also utilise reverse thrust, which would not work with an integrated single engine approach.

See already starting to think out of the box:)

The motor/s RPM would also be easier to regulate.

If multiple fans were used for lift they could also alter their RPM either side to aid turning tighter.

Paul Fitz
16-Sep-11, 08:22 PM
a few interesting ideas! A conventional integrated craft would be out of the question. For efficiency the thrust fan would be large and slow turning. Such a fan/prop cannot produce adequate pressure for a practical lift system. A dedicated lift fan if chosen with care, can be quite efficient. It is likely to be very different from the typical lift fan we see at events.

If starting from scratch I would probably start with a 3 bladed fan, each blade having a wide cord (e.g. like 5z's) running at the slowest possible speed required to produce the pressure.

Thanks for the UH info Wouter, I hadn't seen that before. If their figures are to be believed, they are doing better than I would have expected.

Jason, I agree that Li batteries are improving rapidly, but weight is likely to be a problem for some time to come (Craft weight would be critical). The other problem is delivery of power. Some Li types are being developed which will allow a rapid burst of power and this would be essential on any craft not running on a glass like level surface. If you look at a typical lift fan pressure curve (e.g. Fig 1; Liftfans.Pdf on downloads page) you will see that this particular set of curves have high efficiency and low power consumption at about 160-180 Pa of pressure. You can see that when the pressure increases the power absorption increases by 20-25%. On a racing craft this can happen very rapidly.

It may well be possible to build a battery powered craft but you cannot RACE one craft. Reasonable cost is essential if people want to race (unless your name is Bernie Ecclestone ;} )

Jason Mayo
16-Sep-11, 08:56 PM
It may well be possible to build a battery powered craft but you cannot RACE one craft. Reasonable cost is essential if people want to race
A good point, with todays battery prices the starting grid for electric racing would be a lonely place.
Perhaps this will change in the next few years and we might see a whole new generation of enthusiasts trying to squeeze 6 laps out of their battery pack before they sink into the lake!

datkins
17-Sep-11, 07:07 AM
I've got loads of second hand AA's :)

But I saw an article on a research vehicle that was underwater for 3 months following currents I think in the Atlantic, is used 5000+ D Alakaline cells to ensure that it worked at low temperatures, just imagine opening that many blister packs!

There are new batteries that use "liquid" fuel that are recharged by replacing the electolyte, how much is real is hard to guess as its going to be covered by patents left right and centre but that might allow you to take jerry can of power from home........

david

Al
17-Sep-11, 07:16 AM
I bet the technology is already out there, but the oil companies have bought the rights and hid the blueprints in the back of a cupboard.

yamah
18-Sep-11, 03:52 AM
I am going to have to admit to having the multiple electric lift fans mounted around the perimeter idea some years ago when the RC aircraft fans and motors stated achieving credible efficiencies and light weight.

The idea was to do away with the separate IC lift engine, reduce some of the distribution losses of feeding a finger skirt, probably allow a different hull design as well, and to drive them from the main engine generator/alternator which likely needed to be increased in output to achieve the required energy level. A small lightweight battery and some electronics to control momentary boost and to achieve independence from the main engine rpm and the concept would have the advantages of a separate lift engine without having one under the driver's nose all the time. The possibilities include high kw RC motors as a lift motor alternative and also used for the generator.

This was about the time that small scale hydraulics started replacing the lift motor. I was designing and building a piece of hydraulically operated equipment at the time so had to marvel slightly at the simplicity of what the hydraulic lift fan got away with from a hydraulics point of view. I would have put the fore and aft hydraulic lines in the perimeter duct and changed them to spiralled coil cooling tubes and also added a lever adjustable priority flow valve to control lift rpm. I know it is some added weight which is poison to a race craft, but they were two aspects I would have tried out as I could tell cooling the oil was going to be an issue in the ultra simple original layout.


yamah