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Old Dec 07, 2010, 05:37 AM
Yes, I know it's upside down.
Sydney, Australia
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Manned electric hovercraft

Hi,

I want to build a very light weight hovercraft to carry a person around 65kg. I plan to run it on brushless motor and lipo. I am wondering how much power would be needed to hover and if I can get away with a using a normal propellor.

This is the type of brushless outrunner motor I was thinking I could use.

http://www.hobbyking.com/hobbyking/s...idProduct=5139

It puts out 7kW (about 10 hp?) which was similar to the size of petrol motor that UH use on their smaller full scale models, so I thought it might be possible. Especially since the UH models carry 1-2 people and have proper float boxes, etc, whereas I was going for a very light minimilist sit-on-top design to run around a flat grassed area, and would therefore possibly even need much less power than the motor suggested above.

What rpm should I typically be trying to achieve on the hover motor? Maybe I could mount two normal propellors on the one shaft to get a more "fan-like" effect??

I will use a seperate motor for thrust, and I am fine with designing that, since I have plenty of experience with planes.

Any other thoughts or ideas?
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Old Dec 11, 2010, 12:22 AM
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I want to do the same thing, except with a go-kart. This is the motor I was going to use.
http://www.hobbyking.com/hobbyking/s...dProduct=14427

It makes the one you are looking at look like a joke. It can put out more than 15k W. There is also a smaller one that puts out about the same amount.
http://www.hobbyking.com/hobbyking/s...dProduct=14426

But to stay on topic...
I asked some guys at ERAU (1/4 of the world's pilots graduate from there) about their opinions on electric flight. Even with lipo batteries, an aircraft would be too heavy to fly decent if at all, or it wouldn't have any endurance. Although a hovercraft isn't as weight sensitive, it is still affected by weight. And if you want to have any fun out of it, you would need a decent run time, which means more heavy batteries.

But a hovercraft would be so much easier than a kart...
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Old Dec 11, 2010, 12:47 AM
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You just converted my preference to the hovercraft. After doing a little searching, the kart without electronics would cost around $700. Compare that to a $150 hovercraft body. Double up two 2" thick wall foam sheets from Home Depot. Cut out your necessary holes, strengthen with a little plywood here and there, and your done. No welding required. The hardest part, like always, would be the skirt.

How big would you want it to be?
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Old Dec 11, 2010, 06:43 AM
Yes, I know it's upside down.
Sydney, Australia
Joined Dec 2008
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I weigh 65 kilo, so what ever size is needed to float me. I was going to find out what size batteries the local heli club guys use, then I could get some of my money back on the batteries later.

Yeah, I saw that motor, but my rough calculations suggested I could get away with the smaller one, and I'm trying to do this really, really cheap. If it can't float me, then not really a problem, at least it would be a proof of concept, even if I could only place a 20 lb sack of potatoes on it. I'd see how it performed, learn what I could, and scale up later if necessary.

I know I would only get 5 or 6 minutes out of it, but that's okay, I just want to see if I can do it.

Who knows, if it worked, I might convert it to lawn mower power later.
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Old Dec 11, 2010, 10:11 AM
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I weigh 57 but would like to accommodate for 70. I found some lift fan props, but they are ridiculously expensive - way out of (our) range. It gives a general image of the wide blades or high blade count required to help sustain pressure.
http://www.hovercraft.com/content/in...Path=189_60_83

Here is another hovercraft kit. It uses a 10hp engine for both thrust and lift.
http://www.hovercraft.com/content/in...&cPath=5_33_40

I'm curious to know your budget. I was being idealistic when I posted the 120-70 outrunner. Two of those alone is $600. The motor you posted should work for both lift and thrust if you use two.

What are your ideas for controlling the thrust? a pull-pull system? I like the idea of using a large servo. An ultra fast servo wouldn't be necessary. That way you could either ride with a steering wheel, control it from a distance with a transmitter, or even ride it while controlling it with a transmitter. Also the overall setup with a servo would be lighter, more versatile, and easier to install that a steering wheel to a pull-pull system.
http://www.hobbyking.com/hobbyking/s...ation_list.asp
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Old Dec 11, 2010, 03:51 PM
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I'm getting quite enthusiastic about this. I spent the day so far looking for different components. Here is my list.

Turnigy 80-100-180 $99.95
Turnigy 80-100-130 $100.33
Turnigy Sentilon 100A HV 5-12s BESC (Ver4) $82.07 x2 $164.14
Zippy Flightmax 5800mAh 6S1P 30C $68.58 x2 $137.16
Turnigy Servo Driver $8.95 x2 $17.90

TOTAL (so far) $519.48

Add fly-by-wire steering for $33.90 for a single servo setup, $58.85 for a dual servo setup.

TOTAL with complete fly-by-wire would be $578.33. This is only for the electronic part.
This does not include the hull, propellers, wiring, skirt, and other build materials.
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Old Dec 11, 2010, 08:56 PM
Yes, I know it's upside down.
Sydney, Australia
Joined Dec 2008
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Hi, I noticed that the UH-13PT is for 2 people and uses a 5-7HP engine for lift. The total payload is 500lb (~225kg).

So I figure that building something for only 1 person without fancy fairings, float box, etc. could be half that weight, needing only half the horsepower (2.5-3.5 HP) to hover. So, that got me thinking that 3kW might be enough. The motor I first pointed out can do 7kW maximum, so should run quite efficient and cool at 3kW, plus some reserve power if needed.

The same UH-13T model uses 10-15HP for thrust with a top speed of 40MPH, so to reach only 20MPH would need less than half of that, so again, the same 7kW motor, might be sufficient.

Thrust is fine with a standard propellor, but for lift, I was thinking about either getting a large 4 blade prop, or even bolting 2 (or 3!!) 2-blade props on a single shaft to give a similar effect.

My plans were to work on a much smaller RC version, (maybe 1/4 scale) so that I can get a feel for the design, and because I have been wanting to do an RC hovercraft anyway.

Rather than have holes in the skirt material, I thought I would try having holes in the lower base that could be adjusted in size with blocking plates.

Not going to bother with finger skirt, again trying to keep it simple. Rip-stop nylon would be really light, easy to work with and economic, although not very durable. But would be good start. I know of a guy who uses it for some large scale models, and he paints the outer surface of it so the material does not leak air.
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Old Dec 12, 2010, 08:56 AM
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The fairings could be made of foam. It would weigh very little.

For thrust, it would be cool to spin a 30" prop. The little 20" just doesn't make the look. This would require rpm reduction. A belt from a pulley on the motor shaft to a larger pulley on thee prop shaft would work, but there would be the increased weight of bearing, another shaft, and another prop housing and its accessories. Another way would be to use not one, but two motors on the same shaft. (Thinking out loud.)

I agree with the no holes and no finger thing. That just increases the chances of the skirt getting hooked on something. If I do build it, I would use polyester.
http://www.hovercraft.com/content/in...roducts_id=157
http://www.slipstreamhover.com/Produ...rtMat&CartID=1

I made this based on my smaller one that worked really well. Check my blog and you'll see. The only thing is that the smaller one has a rigid/wall skirt. It is made of only foam, some form of adhesive, and little portions of ply. To prevent it from getting dinged, the top and bottom could be laminated with something. Lightweight and should still be super strong.

The hull is 8'x4'. That would be it without the skirt. The thrust duct has a 32" inner diameter. The motor is represented by that tiny little sphere. That is an 18" prop. The girl is 5'8" tall.
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Old Dec 13, 2010, 07:26 PM
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Change the title to Manned Hovercraft or something related.
- Full scale hovercraft, 1:1 scale hovercraft

The EKG shows a dying heartbeat... I'm already finished the design phase of mine. Now I just have to get it approved. $1k is a lot of money.

After proposal and approval, I'll completely build the hull and duct only.

Final specs:
- 5'2" wide
- 9'2" long
- 6" hover
- 1", 2", 4" foam construction
- thin ply reinforcement
- 32" height without duct
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Old Dec 14, 2010, 08:01 PM
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I went to my local Home Depot to get a price for the foam sheets.
$12.57 for a 4'x8'x1"
$21.97 for a 4'x8'x2"

My design needs three 2" sheets ($65.91) and maybe three sheets of 1" ($37.71).
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Old Dec 20, 2010, 01:22 PM
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Great work and ideas guys, can't wait to see more.
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Old Dec 20, 2010, 03:40 PM
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There is more.
Operation X-Craft: A Full Size Electric Hovercraft
X-Craft: Not a plane but your help would be appreciated
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Old Dec 23, 2010, 10:25 PM
A.PGrapevine
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can't you just put a riding lawnmower engine and some propellers on the underside and the wheel motor on the back to push you forward? it would just take an old lawnmower and some time.
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Old Dec 23, 2010, 10:52 PM
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Four things:
1) Do you have any idea how much they cost?
2) From what I know, it won't work because the motors would be out of their application.
3) Do you really think the designers took weight into consideration?
4) If you were referring to a gas model, it would defeat the purpose of an electric hovercraft.

If that came out harsh in anyway, I'm sorry and didn't mean it. Seriously though, why does everyone try to do things the easy way?
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Old Dec 29, 2010, 05:20 PM
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Charleston SC.
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I have built several UH-10's and from my experience you need much more than the suggested 10 hp engine to get any satisfactory use out of the craft. I personally built mine with a 20hp Honda and modified the air lift box and the skirt intake to get what I truly desired out of my crafts. I was reaching speeds in excess of 55mph and that was on grass or water and I could travel up boat ramps at my local lake. Sand bars and going places canoes couldn't just tickled me pink. I believe going electric is an awesome concept but your going to need allot of thrust and your going to need to have a battery life that will keep you entertained for more than just a few minutes. I have full build pics and years of experience with the UH-10 if I can be of help. Let me know.
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