Composite hull hovercraft being built in Florida

Yes I am.

Flat hard surfaces are what hovercraft work best on (like that old landing field), low friction ice (surface just starting to melting from the sun) is best.

Getting out on to water you keep your fingers crossed during that first test flight. Water is funny stuff if you ask me.

The picture is another one Charlie took.

 

how much air does yours throw out of it kach?,,,are them things under alot of air pressure,,or just huge amounts moved under it?,,,,,man i would get in trouble with a little 1,,hehe

 

Good questions. The answer is you need both in balance.

Air pressure is what lifts up the hovercraft.

Air flow is the amount of air escaping under the skirt, too little and you have friction which slows you down and wears out the skirt. Too much air flow (air gap) and you spray water or dirt everywhere and which happens to represent a loss of lift energy - a bad thing with limited lift resources available.

Loading is a big thing. Loading is the amount of surface area to weight you are lifting up. You want as much lift area as possible with as little weight as possible.

Think of a planing boat loaded just above it's limits, it will not get up on plane easily, nor will it stay up there very well.

Another thing to compare it to is snow shoes, without them you sink in the snow and it takes more energy to get out or walk about.

Walking on water, that's what hovercraft do.

 

Thanks

 

charlie,

I do rember a couple (3 or 4) 47's, their was a 100'+ that our crew (finish)was on. We were never gonna get it straight. I got there in Jan '97, most of the hull was there. Big ol' piece meal project. By that i mean the boat was pieced together in about 20' sections. I could almost bet it had a catastrophic ending.

Dave

 

There was a rumor that one investor was an associate of Warren Buffet's, but it seems Mega Cats went under for some reason. All the mentions seem to be past tense. The current shipyard projects include what looks like an old tour boat being converted into a casino and Grande Luxe, a 228' megayacht fitted out as a floating art museum, There were some articles last year about a project to load the boat up with rare art and visit the billionaires at their homes. Wonder if the bills are having to belt-tighten this year?

 

I guess too little air escaping might increase underskirt temp, maybe cause fan surge and reduced lift?

I've wondered about the transition from land to water. Some hovercraft articles say it's the same on water, mud, and land, but that seems oversimplified. David Drake uses details of fan speed and pitch changes in response to terrain changes as critical elements in his stories about fusion powered 200 ton armored hovercraft. (SF writers love fusion, virtually unlimited power and fuel makes loading issues go away. )

Getting back to reality, I see Kurt's design addressing the loading issue. Huge lifting surface. Composite construction, economical power, and fly-by-wire controls to keep weight down, vectored thrust to get the most out of what gets sucked in ... sounds good in CAD, hope it works.

 

Preventing fan stall or back-pressure so great that the fan blades explode is a consideration. Try punching a beach ball even one not quite fully inflated against your friends heads, there will be a transfer of energy via the pressurized air in the beach ball. When a wave hits the skirt at 50 knots it's like a right hook by a heavy weight champ.

Heat on skirts? Sure friction on asphalt just like car tires will cause some heat. Nothing like my belt sander test for skirt materials, merciless, nothing is fit for use by that measure.

The ultra sonic wear (vibration frequency resulting in heat) of SES bow skirts (a comparable) is interesting and pretty freaky if you ask me. The tips which contact the water wear down several mm's per hours of operation.


http://www.marinekameradschaft-muenchen.de/neu60.htm

 

Found the quote.........................see bottom quote.

http://www.knmskjold.org/logg2001/englog2001_1.htm
http://www.knmskjold.org/logg2001/seal2.jpg
http://www.knmskjold.org/logg2001/hangar.jpg
http://www.knmskjold.org/logg2001/seal1.jpg

 

so,,the worn skirt allows air out,,,,like a bad "seal" on a jar?,,,,i know theres not a "seal",,but i got lack of better word for,,close to a seal,,just suspended a bit over the "jar",,hehe

 

Just like tire wear, it's going to happen, but it's not the end of the world.

That SES can survive a lot more bow skirt wear because of it's solid sidewalls than a regular hovercraft can. On a regular hovercraft it's just going to spray a little more, wear even faster and look bad. There will be a little more loss of air, but that's not the major thing, replacement cost is.

More info..hope it helps.


http://www.hrh.ch/whoiswho/hovercockerell.html


http://www.decastris.com/hcc/what.htm







All the information and graphics for this page was graciously donated by Mike Morton

 

wowz,,,,thats a "bad@ss reply,,,,thinking the best explanation i've ever been givin(the pics are fer me,,,,i dont like reading,haha),,and these float like a boat when turned off right?,,,,if you had a 2 fan one,,,and your lift fan died,,,,could ya still use your thrust to "get ya ashore"?,,,wouldnt it be cool to be able to snap a lever to "re-route" your thrust to be able to use as a lift also in emergencies.

 

Yes they float, some better than others.

Problem with the lift fan going out is that hovercraft are far more efficient than airboats. They just don't have or need big V-8's and eight foot props.

When the lift fan goes out and you add in the drag of the skirt in the water you will be lucky to move at a slow walking pace at full tilt (displacement mode).

Hovercraft can tow other hovercraft, this has mixed results but you do get back home one way or another. The skirt filling up with water can make for a very heavy craft for it's size. If something can go wrong, it will go wrong - be careful.

In shallow river operation, do like the canoe people do, get out and walk thru the water towing your craft. If it's deeper, then a small boat can tow you.

Fixing the craft is often your best solution.

 

UPDATE 01/26/2009

Any news on this topic?