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Scratch Build – In Progress Project: Hovercraft - 23rd June - loads of pics *finished*

Discussion in 'Project Logs' started by profqwerty, 1 Sep 2007.

  1. profqwerty

    profqwerty New Member

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    It can go on both land and water! As long as there is a flat solid surface (eg water, snow, short grass, sand) it will hover.

    Stopping is done by reducing lift engine rpms and letting the skirt and the bottom of the hull drag on the surface you're hovering on - can take a while on ice.

    The fan shifts looooads of air, so you'd need a very good heat sink too:p

    You're dead right the air flow is reversed. I swapped the blades for a set that rotate in the opposite direction:)
    I really really want to finish it before the flooding disappears! It's just started here. If we're lucky it'll freeze and next door turns into a 20 acre ice sheet:D
     
  2. widmod

    widmod Member

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    get a car license plate for the craft :rock:
     
  3. profqwerty

    profqwerty New Member

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    [​IMG][​IMG]

    When testing the thrust system, revving up and down made the engine jump about too much for my liking, so I have taken it's mountings out so I can modify them.
    Ignore the big holes. they're an old mistake:blush:. The smaller holes hold the vibro-mounts (one there) with M8 studding. They're not all ligned up...that's as to position the crankshaft in line with the pulleyshaft, I had to put half the bolts in the mounts in, then roate the mounts so the shafts lined up, then drill the holes wherever they fall. It was a kind of catch 22 - can't put the engine in till the holes are there, couldn't drill the holes with the the engine there. Anyway it's bang in line and the flexy thing doesn't move at all:D


    [​IMG]

    poor little engine on its own.

    [​IMG]

    My very poor attempt at spreading the load. I have a huge amount of diamond tread plating left over (came free with the trailer lol) so I figured I might as well use it. 6mm Ally sheet with the diamond things.

    The idea is to spread the load from the vibro mount over the sheet, instead of on penny washers which could eventually pull through and bend the fibreglass so I can't tension the studding properly.

    The 2 larger holes at the far end attach to the fan frame for good measure:)

    It's not cut particularly straight because: It's a cheapy jigsaw and the blade kept wobbling around, you can't see this as it is mounted on the bottom of the craft, it was getting dark and I wanted to just finish it and get inside.
    However those holes are perfectly lined up right:clap:
     
  4. profqwerty

    profqwerty New Member

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    Fuel tanks + water

    [​IMG]

    These are the fuel tanks - one for each engine (they run on different oil mixes). I drove to Newark this morning to pick them up and got back in time for a late lunch:))

    Sorry about the crappy quality - it was getting dark.

    [​IMG]

    Got back home to find the water is rising so am desparate to finish it before it's too late! Doing up bolts on the bottom of the craft was cold,wet, and smelly - guess why.

    [​IMG]

    The thrust engine is back in now.

    [​IMG]

    The seat on top of the fuel tank. There will be thick foam padding on top to avoid crunching onself:eeek: if the front ploughs into water.

    [​IMG]

    The ally plates to stop the vibrating engine from ripping the fibreglass apart at the bolt holes. The large plate is on the bottom.

    Just got the fuel system to put together now:) and the exhausts:p

    Hopefully tomorrow I'll have some test videos of it running. I suspect the steering / elevators will need modifying afterwards though.
     
  5. zachjowi

    zachjowi New Member

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    that is so awsome do you have more details like what fiberglass you used and where you go the parts?

    thanks
     
  6. tominated

    tominated New Member

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  7. profqwerty

    profqwerty New Member

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    Hmm sorry for the mahoosive delay, I just wanted to get it finished, y'know?

    [​IMG]
    Steering, throttles, engine guages

    [​IMG]
    Lift engine carb, looking out the front

    [​IMG]
    Looking down into the plenum through the lift fan - at the last race the lift engine bogged down (cause STILL unknown!) just as I was transitioning from water to land, and I properly face planted (with the hovercraft!) the mudbank. It ripped a huge chunk of the bottom off. I kept on racing, until the engine died again and the hole let in lots of water and I couldn't go any further:waah: Still got 6/10 though:D

    [​IMG]
    General lift engine. I'm going to remove most of the ally cowling and let the huge fan under neath the engine free air cool it, instead of using the engine's fan. However the pull start is attached to this so there's a but of cutting needed:cooldude:

    [​IMG]
    The whole thing as it is, on it's trailer. I've been stuck outside in a tent as the trailer won't fit into the garage:wallbash:

    [​IMG]
    Thrust engine main mounts / frame. There's a large diamond plate ally sheet on the bottom of the craft to anchor it as well.

    [​IMG]
    exhaust, the middle bit is home made and supposedly helps tune it :p I just painted it and a few hours running and it's gone all rusty again!

    [​IMG]
    Top of the engine + extra mount - with out the top mount the engine rocked a bit far for my liking under load. It's air cooled so the black cowling is for air duction :)

    [​IMG]
    Dual carbs + dirty air filters :grr: This engine alone uses 1L petroil a minute under full power (ie all the time!). Fuel pump and throttle cable splitter on the left. They're a bit exposed and can get kicked accidentally. Yet another thing that needs doing :rolleyes:

    [​IMG]
    EGT / CHT guages for rear engine, you don't really need a tacho. The square one is a digital tacho for the lift engine. You use the tacho to set it up so it's revving at the right speed, then keep and eye on the exhaust temps. If it goes >700C there are problems!

    [​IMG]
    HoverTent to go with the HoverCraft on the HoverTrailer. It's made out of Dexian shelving + gazebo cover. Easily stand the winds (touch wood)

    [​IMG]
    Thrust engine (Rotax 503) with its fan (4*5Z Multiwing fan, 12 blade hub)

    [​IMG]
    random front shot

    [​IMG]
    Rudders behind the thrust fan. Theseare quite large and need a bit of adjustment I think. Also I tend to tow it backwards which seems to be wrecking them :duh: The red bits are flow straighteners behind the fan, supposedly to anti torque it but they don't work 100%.

    [​IMG]
    Rudder attachement / linkage -this bit actually works quite well, just needs a bit of refining to be perfect.

    [​IMG]
    Inside the thrust duct with the belt drive to the fan. This system is capable of handing >200hp, so plenty of expansion room :naughty:

    [​IMG]
    sorry a bit blurry - this fella appeared and looked pretty mean. the ally plate is to cover a hole in the hull i made for an earlier version. It keeps the water out :)

    [​IMG]
    Thrust exhaust system. This gets HOT, so the ally tape is to try and reflect some of the heat. Also looks funky.

    [​IMG]
    aaaannnddd another closing shot.

    Any questions people have about building / operating / repairing / etc please don't hesitate to ask. I'm far from being an expert at hovercrafts, but I made it so have a fair understanding of the operating principles!

    For more info do look at the Hovercraft Club of GB at www.hovercraft.org.uk

    profqwerty
     
  8. widmod

    widmod Member

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    great build log :jawdrop:
    makes me want to have a hovercraft too
     
  9. Farmboy UK

    Farmboy UK Hungry for knowledge

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    That is so unbelieveably cool. I very much want one
     
  10. wolfticket

    wolfticket Downwind from the bloodhounds

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    I have a question:

    Where does the motherboard go? :D
     
  11. profqwerty

    profqwerty New Member

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    As I'm obliged to answer any questions...there's a fair bit of electronics in the engine guages if they're added up perhaps...?

    but I think the next step is making the thing autonomous :D
     
  12. Oreon_237

    Oreon_237 CHEA BRO!

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    and then enter it in that DARPA challenge!
     
  13. jhanlon303

    jhanlon303 The Keeper of History

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    great project but you need to take the day off and celebrate
    Happy Birthday
    John
     
  14. IanW

    IanW Grumpy Old Git

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    Hey Prof, you may want to keep an eye on next week's Scrapheap Challenge (Jul 20). It's their 10th birthday & the challenge will be...

    Hovercraft Racing!
     

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