Wind powered ground effect boat/craft

Discussion in 'Propulsion' started by Cloxxki, Jun 23, 2010.

  1. Cloxxki
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    Cloxxki Junior Member

    Hi all, new guy here.

    For the past months I've been following the DDWFTTW (google it if new to you) discussions and video's, and I'm simply fascinated by the concept.
    With this hirdle (going directly downwind at more than 1x wind speed) out of the way and pushed to near 3x by the BlackBird team of California (on land), I feel the can of worms, even with the thousands of internet posts, is still barely opening up.

    I won't explain DDWFTTW, and please don't you discuss its workings in this thread either?


    My vision used to be a human powered ground effect vehicle. This has been done before, and cycles across the Channel, but that was a paperlight mega lift craft, I want a sleeker, faster, more manoeuvrable recumbent bike style "stealth bomber".

    Anyway, with DDWFTTW inspired technology, I thought it would be awesome to gave the wind power our "air"craft. Pedals optional, although probably worth the addional power to weight for the mod in a one-man craft.

    My basic design is as followed:
    - huge more or less square wing shape (for lift) as hull
    - pilot sits inside it
    - along the surface of the wing, tank tracks.
    - these track have vanes which collaps to become air-slippery on top and fold open to act as a water wheel.
    - the track drives a wheel and shaft, geared to a large air propellor mounted high up on the back (much higher than on swamp air boats)

    The tank track are basically still in the water, with the vanes providing huge traction to be transferred to the air prop.
    Behind the tank tracks, the hull might be extended aerodynamically to complete the pointy airfoil aft shape.
    The pilot could sits down the middle of the hull with a narrow window looking past the tank tracks on the side.
    From the sides of the hull, additional wings/stability floaters could be fitted, or unfolded.

    The large surface of the airfoil, and light overall build, should result in the vehicle laying very shallowly in the water indeed. Say, 15m² flat bottom for 300kg including pilot. That's 2cm average depth with zero velocity.

    The tanks tracks covering most or all of the hull, and laying still in the water for 15m², provide huge traction at minimal drag. The hull is not like a boat, it's more like a carpet continiously being unrolled. You'll visualize how dragging such a large carpets with vanes sticking out as lateral keels would be an anchor to drag being your boat. But if the thing rolls over the surface, you'll see that it will work nicely, behind a low HP motorboat, of even a men's 8 (3-4HP?).

    I just realize that a longer, narrower hull (tank tracks) would reduce rolling resistance over the water. Fewer water droplets are being disturbed. Less frontal surface dealing with the apparent head wind. Larger bike wheels also offer greater traction at reduced rolling resistance, while the weight and air pressure dictate the total contact surface to be identical to the smaller wheel's.

    One option would be to keep the tracks' upper side within the hull, to ease engineering. Airfoil lift might come from outside the hull, retractible floaters/wings.

    Hope you like the idea, and are willing to offer improvements.
    Ideally, a craft would be able to deal with winds from all directions, through nifty airfoils and prop/turbine gearbox. If carts can ride directly upwind with a turbine, why not a ground effect boat? :) At least lots of headwind for lift.

    Looking forward to your comments,

    Regards,

    J
     
  2. daiquiri
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    daiquiri Engineering and Design

    Can you post few drawings/sketches, to help us visualize better your idea?
    One pic is like 1000 words, you know... :)
     
  3. Cloxxki
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    Cloxxki Junior Member

    My drawing skills kept me from trying engineering school...
     

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  4. Cloxxki
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    Cloxxki Junior Member

    For the track, to get both the boyancy and the traction from one structure, I was thinking of the little plactic air pockets that keep our goods intact when enduring the UPS treatment. A polished or teflon coated plate of sorts at the bottom, but supporting the air pocket track from above, would be simply water-lubricated. Support (with some flexibility) is important to spread the load on the water, and adjust to mild obstacles run over.
    The flat on the track would need to be encouraged to grab a handful of water, and then be restricted to open too much. Thin thermoplastic will probably do. Weight is a concern though, better to first underbuild it but get takeoff, than be overbuilt and just lay still in the water.

    The rear end of the track can better be imagined as rolling up a larger diameter wheel, like the second to last, also in that position on the airfoil. The tail flat of the air foil could serve 2 purposes: complete the optimal airfoil, and guide the flap to close against the hull, or go inside it to let the top air flow be cleaner. In the latter case, the pilot and various instruments could be housed in the upper part of the air foil.

    For a top view of the hull and tracks, I was looking at the ~3x6 or 2x8m scale. However, the longer I think about it, the more I think the craft could suffice with less than that, but for boyancy and traction. For the on-water part, at least. But how much would be needed to get near zero slip traction on the air flow under the hull when getting airborne?

    Design ideas would be welcomed for the track. It will need to be light, makable, and offer HEAPS of air grabbing traction. Think of it as a conveyor belt donated to you in a scrap heap challenge, and the only material you may use to make it a better....wait for it.... wind turbine are lots of plactic foil, flimsy strips of hard plastic, and a sealing machine.

    Main hurdle when using the vehicle directly downwind, is that it's extra hard to get the ground effect to kick in. The vehicle will first need to attain ~2x wind speed (difficult enough as it is, on water), for significant air flow will come at it from the front.

    Upwind, the prop would be used as turbine to drive the tracks. Even laying still, there is 1x wind speed to be used for generating lift and exploiting ground effect. 1x wind speed upwind was not managed yet on land, and will be more difficult on water. But flying ground effect upwind on wind power...I don't see how that would be done just yet.
     
  5. Cloxxki
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    Cloxxki Junior Member

    Track through hull.

    It's quite ambitious to say the least, to think the track itself would be moving smooth as a wheel on the road, while offering all the boyancy needed, just with the part that is laying still in the water, at any vehicle speed. I'll show my first sketch what that might look like next.

    Here air pockets with low traction carry paddles. If the vehicle were to have 1 cubic meter of trapped air in the belt, over 40% would be on the water. 400kg could be displaced that way, before the rest of the craft gets "wet".

    Once working with custom trapped air pockets, logic dictates to try and get some serious traction out of those already. Various types of plastic can be used, and it doesn't always need to be for trapping air, it could be structural or to enforce dynamics. As long as it nicely folds around a barrel.
     

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  6. Cloxxki
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    Cloxxki Junior Member

    Small note on the above hull side view cross-section : of course I left out the prop which obviously is still part of the design.

    HOWEVER what I later thought of... Working in reverse, with an inboard engine, such a track design might actually be pretty efficient as a motor boat? Perfect for shallow water that need not be disturbed too much. A bit of a bumpy ride on open water, but the whole thing might perhaps be suspended like a car.
    For drag style boat racers, this design might offer more traction than even a car on burned in tires, on a rubber covered asphalt drag strip...
    I like human powered more though, and when properly engineered, might ben a fun substitute for a typical water bike.
     
  7. rifraf
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    rifraf Junior Member

    Cloxxki, maybe leaving the wind driven prop off the design is a good idea. Having worked with windmills, your craft will produce energy from this unit only when it is still and has wind moving fast past the blades to produce sideways rotation. If the wind generator starts to move in the same direction as the wind (by using this energy to get propelled forward) you get less and less power till you get zero when moving the same speed as the wind and after that only drag, assuming your pedals are enough to provide forward propulsion with no wind. They are also heavy, cause alot of losses due to the moving parts and wind resistance and would place alot of stresses on your craft were it large enough to produce usable energy.
    A sail might at least be able to catch some wind and make you move forward, not faster than the wind though.
     
  8. Cloxxki
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    Cloxxki Junior Member

    Rifraf, I'm sorry to say, but you don't seem to grasp the principle of DDWFTTW. I's real, it works, it's been proven in all ways. Just not applied to a ground effect craft yet, as this poses a greater engineering challenge than a land sailing cart, and even more than "just" a boat.
    Understand this one thing REALLY well : drag on the wheel to DRIVE the propellor, which thrusts like any prop airplane, is less than the thurst added to already present kinetic energy, IF the carft travels directly downwind.
    I don't want to go into this any further, discussion between those who understand and those who won't believe, is a major bandwidth eater.
    Please investigate DDWFTTW and come back with design improvements?

    thanks,

    J
     
  9. yipster
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    yipster designer

    think you have to shape up your engineering and drafting Cloxxki

    i usually like to see new fantasies and free thinking and posting
    and one of the things i use to was drawings for patent applications

    going trough above, your presentation is about the most confusing assumptions
    in crossed linked techno ive seen and i'm having trouble understanding the whole idea

    maybe i'm not concentrating enough beeing side tracked by some of my own
    computer problems, you may or may not have something
    hard to tell now and a word of well meant advice would be: work on your presentation!
     
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  10. kerosene
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    kerosene Senior Member

    Couple of things

    -tracks are not the best ways of capturing the energy from the water surface. Turbine prop would most likely be more efficient.

    -You might want to think some kind of catamaran where the deck would for the wind and the pontoons would have lower drag before becoming airborne and would have the turbine props
     
  11. Cloxxki
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    Cloxxki Junior Member

    Thank you for your responses.

    @yipster
    I am well aware that I can't draw even a convincing stick figure. It's actually the reason I didn't dare to take on engineering school. My inventions tend to be far-fetched, but end up workign when tested.
    I have written some (granted) patents myself, and can appreciate the skills required to make the mosaics, I just don't have them.

    Comprehension of what I'm thinking of here does have a rather high threshold, the DDWFTTW cart and physics are about the most controversial
    thing on the internet of the past years, at least in my fields of interest. Psysics professors have stumbled over themselves to explam that the physics don't add up, it can't be don't. Yet, it can. This thing is destroying reputations.
    I was hoping I'd not need patent-quality drawings here, as I don't need to prove that I have a new idea, I am not looking for monetary gain. And, I don't for now have ambition to try and explain this to even lesser technical people than myself. A Dutch saying goes : "A good understander required only half a word". Yet, I seem to fill pages possibly to the point of confusion...

    @kerosene,
    Could you offer arguments against the tracks please? The way I see it, they have some distinct advantages over a regular water prop. I'll add though, that such a prop should be designed as a turbine, as it's harvesting anergy, not putting out. An airplane prop is different from a high-rpm wind turbine's for this reason.

    What I like about the tracks, is that they could double as floatation member, and effectively lies still in the water. Only movement relative to the water surface, could be the (very limited and low-speed) slippage of the paddles and any suction aft where it's lifted out of the water.
    The way I see it, the ultimate (22nd century) tracks would be more slippery than a catamaran's hull.

    I have contemplated a catamaran track setup, connected by a cockpit cross member shaped an air foil. I bet some catamarans are already sahped similarly.

    I came up with the track idea really out of pre-assumption that an underwater turbine would be too dragging. I don't consider props as effective either, and my mention of an air prop is mostly due to it already working on the Blackbird. I like to think much lower loss setups should be possible to thrust air, and I've seen some promising turbine designs which might translate into better than conventional props.

    DDWFTTW works (exceeds wind speed downwind) on the Blackbird, due to the energy taken by the wheels (ground speed) is translated into a greater amount of torque by the prop. With a low-efficiency transmission, I fear the wind speed will not be broken, let alone sufficient apparent head wind generated to get airborne even with ground effect.

    My ground effect wind vehicle is theoretically possible (only because I say so), but I wouldn't bet on it working without some efficiency breakthroughs.

    I was not able to get good efficiency figures for water turbines, let alone such low speed and pressure ones, but I'll try searching some more.

    Some further thoughts about the track. It "grips" on a surface comparable to perhaps a 1000+ tonnes vessel's conventional prop. The contact surface however is 100% directional with the path of vehicle's travel.
    If you think of a military tank, not a featherweight by any means, this actually keeps a soft soil relatively intact when rolling over it. Due to huge pressure spread, and adjustment to the surface's shape. It's way heavier than a truck the same size, yet conquers the loose offroads with much greater ease, and speed. To the point of having changed warfare.

    Let's for sake of visualisation, imagine a track driven boat, where the (long and wide) track itself offer most or all of the displacement to make it float. Like a lily leaf on the water. The track is driven, the boat starts "rolling". How badly will the water be set in motion? Compare in your mind to a regular boat with underwater prop, same weight and power. And the relative acceleration accomplished. the way I see it, the track kicks the prop's behind, and will do the same when designed as a energy harvesting device still doubling as floatation member.

    But, more importantly : how are we to take energy from the apparent headwind, once the catamaran with underwater turbine is airborne? Will the tiny props do the job to power the huge air prop on the back of the vehicle?
     
  12. FAST FRED
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    FAST FRED Senior Member

    The military tried tracks , and gave up as the speeds were too slow for assault landing craft.

    Today's version used a more conventional drive , and pulls the tracks up to plane.

    Think of the efficiency between a paddle wheel vessel and one with a prop.

    Low speeds fairly close , high speeds impossible with padle wheels.

    FF
     
  13. Cloxxki
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    Cloxxki Junior Member

    @Fast Fred
    Thanks for your input.

    Do you mean tracks as on-water propulsion? Like an amphibious tank?

    My concept, if indeed I'm the first loony to come up with it with serious intentions, is a bit different by being a lightweight-specific one, not for pantsered military purpose. I have thought up various military technology, better than this one, but not even put them on paper for passivist reasons. Warfare is a great inspiration for engineering, just the worst reason on earth to improve. If the wrong power gets ahold of the perfect weapon, mess will follow (nukes are an example, USA murdered so many civilians with that).

    Anyway, the main difference I think is that in my design, the tracks would provide all or nearly all the displacement, of other parts touching the water. Thus, all the contact with the water, and if it really would also with the air when in flight, it pretty much without speed differential to the surface.
    Ideal for a first float (even flight) might be a wide, calm river with siginificant draft speed (say, 4-5 knots), and then some nice tailwind.
     
  14. FAST FRED
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    FAST FRED Senior Member

    They did use extra flotation , tanks on the track mounts, but I think it was to keep from sinking.

    The only use of your setup was buy a friend that took 100+ ft of fire hose sewed it in a loop,and installed flaps to the hose.

    He wrapped the hose on a car spindle with wheel attached, on the stern of his boat.

    As a live aboard in a nice tidal area , he got pretty good power out for battery charging.

    It worked fine although the electrics were never optomized.

    The set up was abondoned as too many boats came close enough to tangle in the slightly submerged hose .

    FF
     

  15. rifraf
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    rifraf Junior Member

    Cloxxki, Indeed i cannot grasp the principle of DDWFTTW, however i find this thread quite entertaining, at least it tickles the brain threads, but am still not on your wavelength sorry, i fail to see how this works, can you provide any numbers?
     
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