Ground effect flying craft, wind powered

Discussion in 'Boat Design' started by Cloxxki, Nov 18, 2011.

  1. daiquiri
    Joined: May 2004
    Posts: 5,373
    Likes: 252, Points: 93, Legacy Rep: 3380
    Location: Italy (Garda Lake) and Croatia (Istria)

    daiquiri Engineering and Design

    I am having a hard time trying to understand what you're describing.

    A fully airborne craft not in contact with the ground or water, with a propeller below the hull and a wind turbine above it? Is that what you're saying?
     
  2. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    You won't see me setting easy goals ever, those are not worth working towards. I am exploring the limits of possibility. DDWFTTW was officially established by Nalsa in 2010. Long after Concorde flew, men on the moon, etc. So, there likely is more we can achieve than the current state of marine/aero technology.

    I have hopes that pressure differences might enable this to work. It would require insane efficiency, but I've not seem why it would be absolutely impossible.
    I realize it's nearly like extracting energy from the same frame as I'm investing in.

    A given is reaching wind speed. The next given is reaching 2* or 3* (thanks to Blackbird), using ground contact of sorts. Then, self-created conditions would be required that allow for extracting from somewhat contained apparent wind.
     
  3. Jeremy Harris
    Joined: Jun 2009
    Posts: 978
    Likes: 59, Points: 28, Legacy Rep: 711
    Location: Salisbury, UK

    Jeremy Harris Senior Member

    To get a pressure difference you need a velocity difference (look up Bernoulli). To get a velocity difference requires a means of either powering the vehicle to create a force (thrust) or physically attaching the vehicle to something that isn't moving at wind speed (the ground or water).

    You cannot get a pressure difference in steady state conditions without obeying those physical laws, unfortunately. Even the very best technology has to remain within the bounds of what the laws of physics allow.
     
  4. cyclops2
    Joined: Sep 2010
    Posts: 242
    Likes: 8, Points: 0, Legacy Rep: 94
    Location: New Jersy

    cyclops2 Senior Member

    Please remember

    To enter into ground effect.

    You must have SOMEHOW built up a speed FASTER than the wind is blowing ...IF IF... you want to coast & land with the wind.

    That is the part that really drives home the requirement of the bird , plane , or boat that it have some powersystem in it.

    To enter into ground effect ...AGAINST... the wind. You can do it for maybe 2 to 30 ?? seconds at best, on a HORIZONTAL SURFACE. No building up energy like a slope glider going down hill all the time.

    You can go with the wind to build up to wind speed ...MINUS... drag...then do a VERY QUICK 180 degree turn directly into the wind and hover until you use up all that stored up speed / energy and reach your stalling speed into the wind.

    You are trying to get unlimited free energy from the wind, while going in a direction that... USES UP... your free stored energy.
     
  5. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    That's the upwind version. The downwind version (speeeed) would have the prop on top, turbine underneith.

    The more I think of it, the more problems I see. But finding solutions to problems is what makes me tick.

    It's clear such a craft would not just be placed in the water and start flying. I am hoping to find mathemetical proof that there are conditions to be exploited.
    I forgot earlier, but this is my biggest stro I'm holding onto:
    A bit far fetched perhaps, but wind RIGHT on the water surface, especially with there are little waves, will be lower than 20 feet up in the air. That is a speed difference that could be exploited.
    The craft sits low, in lesser winds, the prop sits high, in full wind.
    Yeah, I know, the air friction of the craft itself will need to approach zero. I have an invention to take care of that, it seems only useful for the DUW craft. I've called it the open head rocket. It's a cigar shaped craft with air inlet and exhaust covering the full frontal surface. Air is sucked through by a magnetically floating shaftless prop (unfortunately patented recently by a fellow countryman of mine), inside a narrow duct. Between the duct and the outer cigar shape, there is room for payload. The craft would see less oncoming air than a typical rocket.
    Two OHR's might make the thrusters on the DUW cart. One OHr might work as a DDW prop, but it's a heavy design until I solve that. An inflatible electrically driven propellor, I see possibilities. Not kidding.
     
  6. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    Nearly impossible, right?

    To get airborne, a model craft could unroll a half-wide roll of strong toilet paper (sticking to the water surface, or just fish line and a little bouey), and have that drive the prop. Be it upwind or downwind.
    Once airborne, wicked conditions and tech will be required to harness the wind's powers. Wind speed differential between above the surface and higher up are my best best for now. If only I could learn conditions to exist that offer 3* wind speed differences between 1m above surface and 6m above...
     
  7. cyclops2
    Joined: Sep 2010
    Posts: 242
    Likes: 8, Points: 0, Legacy Rep: 94
    Location: New Jersy

    cyclops2 Senior Member

    The most common uses of Ground Effect are to....SLOW DOWN ...a object due to the EXTREME lifting of the front of the vehicle. ....AIR BRAKES....you tilt the vehicle / bird to the ...MOST draggy .... angle possible. That gives you lift while consuming power from the the bird / plane / boat.

    You are trying to get ....SOMEHOW... more energy into a object than you are using up. TOUGH logic to accomplish, with our science as we know it right now.
     
  8. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    Luckily, the craft has an upside and a downside. I like to cheat the laws of nature, it has offered us a lot of loopholes. DDWFTTW is one, and I am looking for a few magnitudes of difficulty higher.
    DDWFTTW was by most wind and physics specialists dismissed as impossible, even though the physics, once proven, were relatively easy to explain.

    My biggest hopes are on wind speed differentials at this point.

    Wind powered ground effect is the holy grail, likely never reached.

    In my younger years, I was already dreaming of a pedal powered ground effect craft. Of course, these existed already. Very fragile and huge. Crossed the Channel even I think. I dreamt of a smaller, more fighter jet like craft, yes much like the engine powered ones. More speed, same lift, from lower frontal drag and smaller wings. Flying it over land with ditches and low fences would be sooo cool...

    Idea: the craft could unwind a floating fishline, fly a number of miles until it runs out, and then use the air prop/turbine to haul it back in. Repeat. Cumbersome, but it beats having a train that needs to lay its own tracks.

    If I can avoid needing ground contact, that would make the invention magnitudes more significant. So that's what I'm ultimately after. If the craft should turn out to HAVE to be slower than the wind, I wouldn't care. Like a leaf in the wind, that can steer and stay close to the surface. Cool enough for me.
     
  9. cyclops2
    Joined: Sep 2010
    Posts: 242
    Likes: 8, Points: 0, Legacy Rep: 94
    Location: New Jersy

    cyclops2 Senior Member

    Now you have a chance with the craft BEING SLOWER than the wind.

    Worth doing low drag, water & air, designs. Combining the best of each, if possible, into 1 water & air vehicle. Could be very possible if a certain wind speed was available to make up for all drags.

    Go for it.
    If you get lucky. Do a very smart thing. Get 1 of the MOST HONEST patent lawyers to protect your findings.
     
  10. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    You are of course right.
    Ground effect, although taking energy, has been proven to be more efficient for tons*miles than most or all other air or water crafts. It's doing SOMETHING right. I've read that a wind is very efficient in generating lift. It gives a lot of lift, while taking little energy. Said differently, it allows for low take-off speeds. When you exploits those fully for payload, you also get a altitude ceiling in the meters range. It needs the air bubble to float on top.

    But now let's accept a low-flying ground effect craft...with a huge propellor/turbine very high up. A large lightweight craft with triangular 3-hull configuration could offer both lift, and a very high placed prop/turbine. then we get wind speed difference.
    OK, I'll admit, that's the one hope I still have. Say, there's 30m/s winds up at 10m. 15m/s where the wind flies.
    The large prop (DDW) would ensure approaching wind speed (30m/s). The uniwing would already see 15m/s apparent headwind at those speed, possible well enough to be flying already. Create drag for lift.
    Airborne at 25m/s, seeing both tailwind at the sail/prop on top, and headwind at the hull.

    Hmm, I now get intriqued. What if the prop/turbine link could be done with altogether? I'd love to hear whether ground effect model builders ever tried to fly them DDW. I've seen a guy using them in a sports hall. Wooden models. Just giving them a push, they'd fly till dipping below stall speed.
    Upwind, it surely won't work would an prop/turbine link. But downwind...?

    I'm not trying to claim I know everything or you guys are wrong. I am challenging your knowledge, to advance insight. I have plenty of wind-related ideas that WILL work. Like wind powered bullit trains. That's easy stuff to come up with or implement, compared to this.

    Thanks for all your input, keep it coming!
     
  11. Jeremy Harris
    Joined: Jun 2009
    Posts: 978
    Likes: 59, Points: 28, Legacy Rep: 711
    Location: Salisbury, UK

    Jeremy Harris Senior Member

    Please try, I don't want to dissuade you from an experiment, but I know enough about physics to say with certainty that you cannot get energy from nowhere, which is what you seem to be proposing.

    Somehow you have to get an energy input into your craft, both to keep it up and propel it forward. To do that using the wind you need to be able to harness wind power, which means creating a differential velocity between the wind and the vehicle. Without either thrust or an attachment to the ground or water you're not going to get any differential velocity and you're not going to be able to extract any energy.

    When it comes to HPVs and aircraft in particular, then you'll have seen that all of them have converged on similar solutions; big wingspan, very low airspeed and very light construction. That's not because they copied each other, it's because the only way you can lift the weight of an aircraft and human being with a power level of a few hundred watts peak is from that configuration. Reduce the span and two things make the aerodynamics worse, the aspect ratio decreases (giving higher induced drag for a given amount of lift) and the wing loading increases (the ratio of total weight to wing area). Both mean more power is needed, or to put it another way, efficiency has reduced. The reason human powered aircraft fly slowly is also down to the laws of physics. The power needed to overcome aerodynamic drag is proportional to the cube of airspeed. Double the speed and you need eight times more power.

    It should be perfectly possible to build a wind-powered ground effect vehicle, and maybe you'd be able to crack going upwind. Ground effect increases wing lift coefficient so you can get more lift from a given wing area than you can outside ground effect. It's limited to low height, usually less that one wingspan. The best example would be to think of a low-flying kite, where the string was fixed to a braked kart or sea anchor and the kite was tethered and controlled to fly just above the surface. Such an arrangement would fly downwind fairly easily and be able to lift more for a given wing area than a high flying kit. There are lots of control challenges to overcome, because control response, and control surface area, is proportional to the square of airspeed, so halving the speed means having control surfaces that are four times bigger.
     
  12. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    Thanks for the support. I already have a couple patents granted, albeit under a friend's name.
    Lately, I am into open sourcing. it's the way forward.
    If I revolutionize something big in society, I will tell everyone I did it. I will speak at conventions, have my own action dolls, sell the book rights, all without selling one patent or device. Let the open market make the best of it.

    You set me on a good track. Low ground speed, high wind speed, that opens possibilities. heck, a hover craft could work like that. Air intake on top, draggy hulls, air gets pushed out underneath. Many ways to skin this cat.
    The air-air linkage towards high speeds fascinates me though. Any ideas for that are welcome.
     
  13. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    Great pointers, thanks.
    I believe in advance of science, so if decades ago a HP plane was like 20 meters wide, we'll reach a day when it's only 15m or 10m, or even less.
    I need to understand that aspect ratio deal better. Gound effect certainly is a bigger part of the equasion for me than those few pedaled planed we've seen. It's would stick to the ground, is how I see it. Half a wingspan would be plenty for me. I'd been thinking in the 6m range.
    With a prop up high, I might get an extra boost when pointing it DDW?
     
  14. Jeremy Harris
    Joined: Jun 2009
    Posts: 978
    Likes: 59, Points: 28, Legacy Rep: 711
    Location: Salisbury, UK

    Jeremy Harris Senior Member

    Human powered aircraft can only fly in ground effect, which is why they are always so low. Ground effect for them, with those big wings, means a reasonable altitude though.

    Don't expect massive gains from ground effect versus out of ground effect though, it's noticeable, and worthwhile in terms of increasing lift from a given wing area or decreasing the power required because of reduced induced drag. Induced drag is a function of lift and aspect ratio and a ground effect wing has an apparent aspect ratio that is significantly greater than its measured aspect ratio, due largely to the tip vortices being constrained by the ground.

    Reducing the span for the same performance and power isn't a question of science or technology development. It's determined by some basic laws of physics (things like air density and viscosity), so the sort of span reduction you're talking about isn't feasible. Some things are possible because we'll gain a better understanding with time, some things will never be possible without changing our physical environment so that the current laws of physics no longer apply.
     

  15. Cloxxki
    Joined: Jun 2010
    Posts: 28
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Netherlands

    Cloxxki Junior Member

    I can see what you mean.

    I meant development such as the recumbent bike has seen. The constraints were always the same. One man, a crankset, and an aerodynamics shape covering 2 wheels and the rider. Still, they get quicker bit by bit. They've now reached the point where the advances get quick small. Did the first successful attempts as HP flight get the optimum out right away?
    Prop design has some room for improvement I would say. A slightly smaller uniwing craft could have flexible flaps getting that little bit extra reach for the ground without a slight brush being an issue. I really like inflatible solutions. Good internal support from weightless structures which can take a hit.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.