Hey look Hovercrafts are boats

Discussion in 'Boatbuilding' started by Boston, Mar 13, 2011.

  1. rasorinc
    Joined: Nov 2007
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    Location: OREGON

    rasorinc Senior Member

    Why use skirts? Rent, buy or borrow a large tractor tube, use ropes to shape it to what you want, then fill it with helium for lightness and put your super structer on top.
    Just an idea for you to make it more simple. Drape crepe paper over it to look like a skirt
     
  2. viking north
    Joined: Dec 2010
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    viking north VINLAND

    Man it getting less complicated all the time, wonder how much weight a helium filled tractor tube would lift. Then again it could be filled with hydrogen. That would go over with a bang :). Another thought if a tractor tube was not available just invert one of those cheap plastic swimming pools and fill it with helium balloons with a net to keep them in. How much time have you got to experiment?---Geo.
     
  3. Boston

    Boston Previous Member

    I have about a month to go
    cardboard eh
    probably a lot cheaper than foam although the foam is so easy to work with

    dimensions are 8x12 and ya I could put it on casters or just plug it in using regular AC fans. its only gotta work for a few moments.

    hmmm
    lots of good input folks
    and right idea Paul
    you'd be surprised how crazy a star trek convention can get
     
  4. kach22i
    Joined: Feb 2005
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    kach22i Architect

    Boston, what ever happened with this project?
     
  5. Submarine Tom

    Submarine Tom Previous Member

    He realized it wasn't terribly "green".

    -Tom
     
  6. Boston

    Boston Previous Member

    its in bits and pieces sitting in the back yard. What can I say I get distracted easily. The starcon is coming up in about three months and I've been meaning to get cracking on this thing so I'll try and post some pictures once I get things assembled. Its pretty much just a pile of tubes at the moment. And I don't have a motor yet. I might just float it on casters and inflate the skirt with the two fans. No clue but I've got to limit the build budget to something reasonable and a real working model might just be out of the picture

    cheers
    B
     
  7. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Boston,

    Go to Universal Hovercraft and look at their 13P (I think) model. The plans are only $40. The deck is just 1/4" ply, there is styrofoam under that to make sure it floats (if you take it over water) and I think the skirt is nagahide?

    The motor is about 5HP lawnmower but the blade is a fairly complicated build.

    The only reason to suggest looking here is that it shows you something that has actually worked, though probably more than you need. Possibly the guys there would suggest what would be a minimal lift motor - they seem to have lots of experience.
     
  8. Boston

    Boston Previous Member

    well I didn't get the hovercraft even remotely done enough for this years convention but I did get a lot of other stuff taken care off.

    [​IMG]

    The lovely Jenifer

    getting a shot of nonotechnology

    [​IMG]

    Needless to say the Borg costume went over huge, even the main guest star asked for my picture, Johnathan Frakes. He left his seat where he was signing autographs and walked up asking for my picture. Couldn't have had a nicer compliment to all the hard work that went into that thing. Even made the local newspaper

    there's a laser in the headpiece as an LED light but its hard to see unless I'm looking right at the camera


    [​IMG]
     
  9. hospadar
    Joined: Apr 2011
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    hospadar Junior Member

    If you use polyester or vinylester, you'll have to use a more expensive foam (IE not styrofoam). Might be worth the trade-off though since styrofoam is very limiting in terms of what solvent-based finishes you can apply to it.

    Home insulation spray foam is a polyurethane foam that you could apply poly/vinylester to, it's easy to sculpt too, and can be sprayed on where you want it then shaved away.
     
  10. Boston

    Boston Previous Member

    actually I'm going high tech, I think. Who knows what I'll end up with. But from the hovercraft homepages calculator I should be able to lift 500 lb 2 inches with about 6 hp. So naturally I'm thinking of using a bit more than that. Thing is, its never going to see water, so I'm thinking electric. I have a few 1/5 hp 1/2 lb 115 vdc electric motors that would fit model airplane props just fine. I can get all I want at $5 each. so I'm thinking of multiple lift fans running off a bank of 9v batteries. <------ turns out to be ridiculously expensive to do this The motors are 1.2 amps and I'm not sure how many amps are in these alkali pile 9v bats, but if I remember its variable, depends on the battery. But something tells me that since I'm going to want something like 14 in series and at least two banks each motor I'll have to find some with the 1.2 amps I'll need at peak draw. It only needs to operate for about 10 minutes, although I'm thinking rechargeable instead of these alkaline ones I have in front of me. maybe some cheap rechargeables but even that is looking pretty pricey

    Then of course I need a drive fan, two actually and maybe four, depends. I might use a large fan blade from a basic house fan and rig it to a few of these little motors I have, that way all the battery packs are the same. That and the motors are $5 each.

    I figured a 12 foot long platform 6 feet wide and weighing a total of 500 lbs including 190 for my fat ***. I'm thinking 36 of these small lift fans and maybe another few for the drive fans. quite a few actually but

    I'm still undecided about the base material but once I figure out how much I'll need I can see what the various prices are going to be. Might just consider a tether/power cord as well.
    cheers
    B

    OH
    a question for our resident electrical engineers, were would I locate a power controller for a 115v DC circuit, or could I just build my own, I'd rather build it myself onto the surface of the vehicle anyway. OK having just looked into what 500 rechargeable 9 volt batteries cost its probably cheaper to make convert 110ac to 110dc and live with the slight power drop. seems like a few capacitors and one whopping diode bridge would do the trick. Anyway I'm a cheap bastad so my theory is I can run a 115 volt motor on 110 volt of wall current, which if I remember varies anyway. So I might just be able to draw 115v . I can run the thing on a power tether, its a stage prop anyway. Never going to see water, although if I did end up using batteries I could run it on the lawn just for fun ;-)

    great, I'm seeing problems with the tether idea as well. I've got about 6 hp of lift or 4,440 watts divided by 115v ends up about 40 amps. not likely to be dragging that power cord around behind me very effectively. Damn and I really liked the electric motors idea. I'm not sure the convention will let me fire up a gasoline engine in the main banquet hall. I can hover at 1/2 inch with about 3hp which brings it down to 20 amps but then there's nothing left for the directional fans and 20 amps is about as much as I could expect out of the stage outlets, I think. Maybe. Gotta make a few calls and find out what the rules are.

    this next brilliant idea doesn't end up working all that well either
    hmmmmm, found some mini 12 volt lead acid batteries cheap that might just do it, granted the battery pack would weigh in at 120 lbs but its almost enough if I lower the hover height to 1 inch, I'd only need 3 hp so I'm calling it 4. So 20 1/5 hp motors drawing 1.2 amps each means I'm taxing those bats pretty well. I'd have one bank made up of 2 parallel sets of 10 batts in series. so 120v and 16ah. Thing is I'd be drawing 24ah so my batteries would heat fast. I could use some dry ice, would make for a "cool" effect ;-)

    but at about 3am I did find some model airplane electric engines that pound out a whopping 2000 watts, so looking into the bat packs for them now.
     
  11. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Boston, how about a gas motor direct driving an automotive alternator with the rectifier to get DC. 60 amps should be easy to obtain. You might be able to get by with a 4 stroke weekeater motor - never looked at their power so I don't know what you need.

    5 minutes - 4 stroke so little smoke, might be accepted if you muffel it well.

    Sound like you are having fun.

    Marc
     
  12. upchurchmr
    Joined: Feb 2011
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    Location: Ft. Worth, Tx, USA

    upchurchmr Senior Member

    Another thought, just use compressed air with an airbearing. Accept a small ride height - .1 inch, hide the bearings under a skirt, use a battery powered thrust motor. Can you get a scuba tank and a regulator to have a very slow usage rate? at a low ride height an airbearing is very efficient.
     
  13. Boston

    Boston Previous Member

    can't do a gas motor inside the building, also even a 3000 ft tank doesn't have enough air to lift much for more than a few moments.

    But I did find some pretty slick 4hp electric motors $100 each with a prop of 21x13 ( about $15 ) that would definitely lift this thing. 2 plus speed controllers ( $100 each )and power packs ( no clue how much they cost yet ) would do the trick to lift it more than I'd ever need. 8hp gives me a clearance of almost 3 inches, which I believe is measured from the bottom of the skirt to the ground. At 500 lbs I could make do with 1' clearance on 3hp but one of the guys in here is the man when it comes to hover craft and he's suggested its always best to have excess lift.

    Anyway waiting to hear back from the company that makes the motors on the recommended battery pack + charger

    oh, and universal hovercraft has an electric model they're working on but its every bit as ugly as all there other designs, damn someone down there needs to take a styling class or two. Looks like something a ten year old threw together. They do however have the lift fans and other bits and pieces on sale, so that might help. I guess there power packs are made up of 4 5ah 11.1 volt polly packs. Gotta be rechargeable Nihd in which case it can't run for more than a few minutes at best. Like ten or something.
     
  14. beernd
    Joined: Jun 2012
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    beernd Junior Member

    I am afraid that I am far too late but anywaya receipe for home made glue:

    1 cup of flour
    11/2 cup of water
    1/3 cup of sugar
    1tsp of vinegar


    In a saucepan mix 1 cup of flour with 1/3 cup of sugar.
    Add half of the water required and mix into a thick paste without clumps.
    Pour in the rest of the water and combine till the paste is smooth.
    Pour a teaspoon of vinegar and put on medium heat until the mixture starts to thicken.
    Cool and transfer to jar or an airtight plastic container.

    This glue will keep for a few days. Refrigerate to prolong the shelf life (the jar in my fridge is 6 months old).

    Vinegar in this glue recipe acts as a mild natural preservative. You might use grapefruit seed extract or tee tree oil (5-10 drops) instead of vinegar to naturally preserve the glue. Stick with vinegar though if you have small kids – not only is this glue non toxic, but perfectly edible too!
    This glue needs more time to dry, but when dried, the bond is really strong.


    Oh well my 2 cents worth.

    Cheers
     

  15. alaskamokaiman
    Joined: Oct 2006
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    Location: Palmer Alaska

    alaskamokaiman Junior Member

    Make a light strong wooden frame built on a cheap electric scooter cover with papermache add skirts the illusion of flying. Just turn the fans don't make the do the work.

    Use cooked corn starch instead of flour it works great very strong when dry.
     
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