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Flying hovercraft

Flying hovercraft

Flying hovercraft

(OP)
So Ive decided to build one of these from scratch to pass the summer.

Im slap bang in the middle of 3 great lakes here in Ireland so Im thinking its time to bring to next level and go airborne.
Have done the sailing/speedboat deal so its the next 'sensible' step.

They are nothing new of course, Ill be running mine with an 2.0l n/a Subaru boxer engine. Everything else is kind of still in my head, but how hard can it be.

http://www.youtube.com/watch?v=qqxygnJIQVo

This place appears to sell them built, and in kit form - built they are 179,000 dollars (what?)

http://www.hovercraft.com/content/index.php?main_p...

Cobble together kit form, prices are still a bit 'what'

http://www.hovercraft.com/content/index.php?main_p...


Have all skills to pull it off solo so I intend to enjoy it,

Anyone ever piloted one?


Brian,



RE: Flying hovercraft

(OP)
A ground effects winged hovercraft? No he hasn't....

RE: Flying hovercraft

(OP)
Just to clear this up, its a hovercraft that relies on ground effects for flight(see video in op)

No license needed as it only goes 5-10ft high,

Brian,

RE: Flying hovercraft

(OP)
Saw those - they look like fun, wayyyyyy too much r+d + money though - for something that probably wouldn't work, or kill me.

At least with hovercraft, Im sure I can get into the air with it. And if not, just add more hp and play with levers some more,

Brian,

RE: Flying hovercraft

Just a cautionary note. My only experience with hovercraft (non-flying at that) is in northern Lake Huron where I have a summer place. We islanders have no road access so in the summer we boat and in the winter you can snowmobile, dog sled, snowshoe, etc. In the shoulder months when the ice is forming or breaking up a hovercraft is about the only mode of transport short of a helicopter (have yet to see one of those). My neighbor, who has considerably more money than I, has a year round caretaker and a hovercraft. Unfortunately, he is on his 3rd caretaker. The first one capsized the hovercraft and although he made it to mainland he died of hypothermia. The second one also capsized the hovercraft and drowned. I know the first one had years of experience driving it, the second did not make it that long.

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: Flying hovercraft

(OP)
Dgallup,

Thats something I wondered about. The lakes here are pretty safe, as in ok water temps, my testing lake is probably 10ft deep average, but 'dig in' worries me a bit - and getting thrown from seat/overturn it etc.

I think/have seen the main danger is when hovering sizeways or washing sideways on a turn, craft rolls, and digs in, turning it over.

I have no idea how they feel to pilot, but I guess Ill just take it real easy. Much of my 'driving' will be straight line only, with no rocks, and sandy shores to run up onto.

Just trying to source foam for hull/bed now, It will be mainly hotwire cut, with some fettling. Over that, ply/glass and so on.

Brian,

RE: Flying hovercraft

Quote (IRstuff)


"but how hard can it be"

Well, Moller's been trying to make one for about 25 yrs..

I have been studying the Moller Skycar. It is fascinating. According the the website, the Moller Skycar weighs around 2500lb and it flies at around 300mph, getting 20mpg in the process. It has a total of 700hp. A Robinson R44 has a loaded weight of around 2500lb. It is a vertical take-off machine with 245hp, and a top speed of 150mph. A Rutan Boomerang weighs 4200lb maximum, it does 311mph on 410hp, and I would crudely guess the wing's lift to drag ratio to be around 15:1.

P=FV

Boomerang Thrust...
Fb=P/V
Fb=(410hp × 550 ft.lb/sec.hp)/(311miles/hr×5280ft/mile×1/3600hr/sec)=495lb.

Wing drag: Dw=4200lb/15 = 270lb.

This means that a Rutan Boomerang requires 500lb thrust to maintain speed, 270lb of which is used up by the wings.

The Moller Skycar has a fuselage approximately the same size, flying at approximately the same speed, so it should require around 250lb thrust. It weighs 2500lb. It is propelled and lifted by ducted fans, so the required thrust vector should be arctan(10), about 84° down.

In animated views of it flying, the ducted fans always are pointed directly to the rear. By my estimate, this configuration would happen at fairly high supersonic speed. Helicopters fly with their rotors fairly to close to horizontal.

If you look at the hovering Skycars on YouTube, you will see a crane in the background.

Perhaps I am doing something wrong here. I am not an aerospace engineer. I would be glad to be corrected.

--
JHG

RE: Flying hovercraft

Moller has been at it more than 30 years I think...fwiw I worked for him in the mid/late 90s and helped build one of the first M400 prototypes.

RE: Flying hovercraft

Kenat has the right google term with WIGE (Wing In Ground Effect). Ekranoplan (or Ekranoplane) is the other google/wiki search term.

RE: Flying hovercraft

Every time I think how cool it would be to have an Ekranoplan, I Google them and read about the spectacular crashes they've had. ... sort of like those uncontrolled pitch-up crashes you see with unlimited hydroplanes and drag boats, but with much bigger vehicles.

Mike Halloran
Pembroke Pines, FL, USA

RE: Flying hovercraft

Yes, and more typical is catching a wingtip on a wave or obstruction. Having a chase boat and the same type of fast-egress hatch in the bottom of the hull that the unlimited hydroplanes use would be a good idea. Full harness racing restraints and roll cage, small scuba tank for the pilot whilst he waits upside down and underwater for the crash team to arrive...trauma team on standby at the hospital, medevac chopper fully warmed-up on nearby landing pad...

RE: Flying hovercraft

(OP)
Ah you have to live dangerously too....

Couldn't be any worse than being upside down in a rally car while in a river so narrow you cant open doors...

Brian,

RE: Flying hovercraft

Regarding the skycar&crane, that was driven by faa. Apparently tethered flight is okay.

I recall doing wind tunnel testing of a scale model back in the 90's, but I dont remember any details of the resukts. It was one of my most fun jobs ever. We played racquetball on a court next to the dyno cell every night.

RE: Flying hovercraft

Gstdiscovery: Sky car created by paul moller

Do the fans thrust in the direction they are pointed, or is there some additional ducting? Note how the thing moves in the direction of thrust. It appears to be swinging.

I have Flight Gear installed on my home computer, and I have a model of the Skycar. I don't know who created it or if there is any connection with Moller. It shows vanes at the rear of the ducted fans, which might be doing something.

--
JHG

RE: Flying hovercraft

No issues, Brian. Last fall I was about 5 miles back in some steep wooded terrain, after letting my wife know my general area of play within about a 5 square mile radius...about a mile from any road or trail and way down in a hollow where no way to get cell coverage...and slipped on a fallen log and went over backwards...and the log rolled onto my shin. I was stuck there for a good 5 minutes before I could free my leg, as my body was more or less hanging down from the trapped leg at a 60 degree plus angle, and I couldn't hold myself up for more than a few seconds at a time before needing to fall back and rest. Contemplating what a stupid news article would be written about my demise was the motivation to unstick myself. My point: we all choose our dangerous hobbies. I was lucky that the bear I was looking for didn't happen by at that moment...

RE: Flying hovercraft

The one I worked on had vanes at the back of each nacelle to vector the thrust, but I'm told that more recent models rotate the nacelles.

RE: Flying hovercraft

Hey Brian, that looks like fun. I'm a little leery of the risk of dipping a wingtip at 100 knots, though.
Have you thought of visiting the factory or test-flying one of them? Just to confirm that you get a good "feeling" piloting one. If it turns out you get the willies, well it would be better to find out before building one!

STF

RE: Flying hovercraft

(OP)
@Spar, ya, wing dip is the fear for sure, but I think Ill just stick to going straight, and very calm days until I feel up to more. Have never flown one, but ''have no fear''....famous last words eh...

Build nicely underway now, thrust duct almost complete, hull parts in the vac bag. Been eying up Subaru foresters as theres a few about for sale with failed Ncts(MOT) due to worn components - makes no sense to repair as they are worth nothing, so thats going to be my donor. They can be had for 400euro

Looks like Ill have to do the main prop in two 'go's on the cnc as my x travel is a little short, but thats do'able too.

Been toying with the idea of making the lift fan hydraulic driven to cut out mile long belts, but I have to brush up on my hydraulics a bit, its been years since I laid out a system.

Brian,

RE: Flying hovercraft

speaking of the hoverplane, it ought to be faster than most conventional speedboats, ya?

RE: Flying hovercraft

(OP)
Mike, Gps is telling me 35mph in the speedboat, thats at fill tilt with a 60hp outboard. It feels like 80mph! The ground effects hover craft is calculated to do 60mph, so that should feel very fast. I cant comment on commercial type crafts.
One thing I like about the hovercraft is that there is no wake(much), and none at all when in the air - until you crash that is,

Brian,

RE: Flying hovercraft

I wonder whether you could fly it high enough for Caribbean adventures?

RE: Flying hovercraft

One thing I like about the hovercraft is that there is no wake(much), and none at all when in the air - until you crash that is,

RE: Flying hovercraft

One thing I like about the hovercraft is that there is no wake(much), and none at all when in the air - until you crash that is,
Brian, Are you talking about the kind of wake that takes 3 days?

RE: Flying hovercraft

(OP)
LOL, yea, Irish style, make it 4 days,

Damn you got me good there, had a right laugh!

Mike, Im not sure the fuel tank is large enough to make it that far...

Ill be interested to see how high it can go when Im 'confident', I dont think I'll ever be fully prepared for what may happen though.

Brian,

RE: Flying hovercraft

I was just thinking that one based in florida might be able to travel quickly to/from latin america without all the pesky intercessions that a regular speedboat can face.

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