Wing in ground effect boat

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Starman, May 20, 2010.

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  1. Jun 15, 2012 #61

    FlyOver

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    Apparently, HW20 is in production. They are trying to built the first HW20 in Germany. Please check their website Welcome to Air Foil Development | Air Foil Development | Agec

    This HW20 is different from the Airfish 8. HW20 boasts a few improvements such as shorter takeoff, improved stability (or safety) and better turn radius. Quite a nice looking boat I would say.

    In that website, it says it is looking for partners. I have tried to contact them to ask for what kind of partners are they looking for. They replied that they are looking for partners to invest together to help to commercialise HW20. So, perhaps one of you who have enough interest and money could join their partnership.

    Anyway, I can't wait to see good news from HW20 that it is flying.
     
  2. Jun 15, 2012 #62

    orion

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    From what I see at the web site I would't hold my breath. This has been the classic format for these things for the last couple of decades - they really don't have anything yet, nor do they have the funding to complete the design or prototype (the German government has backed away from funding these craft any more). As such, they set up a nice web site with lots of pretty pictures and then try to hunt down the money necessary to move the program forward. The problem though is that in virtually every case the amount of money has been significantly underestimated, which simply means that it'll have to go though these start/stop cycles a few more times before you see a piece of hardware.

    Don't get me wrong - I too hope they make it work. But history is a pretty good teacher.
     
  3. Jun 16, 2012 #63

    Starman

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    Last edited: Jun 16, 2012
  4. Jun 16, 2012 #64

    Starman

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    OK, it looks like since I moved to Ecuador that I won't be making a WIG any time soon so I will, for FREE, give away some of the great breakthrough WIG design secrets of the world's best airplane-cartoonist/natural-born-physicist: me.

    Take off power with engine efficiency: Since WIGs require so much more power to take off than to cruise in the air with this creates a problem of having to drag around a very big engine, the weight of which is largely wasted plus, the fuel efficiency of a loafing engine is not as good as one which is working moderately hard. The best solution for this is to use two engines, one just for takeoff and the other mainly for flight but it will add to takeoff power.

    The engine for take off uses a water prop which is retractable, and it should be a two stroke for light weight. The poor fuel efficiency of a two stroke won't matter because it will be used for such a brief period. In fact a standard outboard motor could be used for this.

    The small flight engine can be a standard air cooled aircraft engine. Even better would be a small water cooled diesel for maximum fuel efficiency and long range.

    This combination gives you the lightest weight and the best fuel efficiency.

    Next I'll explain how to make WIG aircraft stable, the easy way, but got to go for now.
     
  5. Jun 16, 2012 #65

    orion

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    This is not really a design secret - at least a dozen programs have tried variations of the themes. Some were somewhat successful while others were not at all. But nice try.
     
  6. Jun 16, 2012 #66

    topspeed100

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    I have put a lot of effort to get advantage of the ground effect in ligting body/blended wing design.

    I see it has advantage in low powered airplanes since the ground effect deliveres in some estimates 250% more lift. The retractable under gear uaually causes lotsa drag and therefore you need to put more power to it...ground effect gets the craft and gear up for early retraction.
     
  7. Jun 17, 2012 #67

    orion

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    Not even close. Here is one area where there is a huge difference between theory of wing-alone predictions and real world practical applications. As a matter of fact, for lower angles of attack, the presence of the ground plane can actually cause negative lift coefficients, sucking the craft down into the surface.
     
  8. Jun 17, 2012 #68

    topspeed100

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    This info on 250 % lift is definetely made by "pure" side closed devices only ( claim is on WIG site )..normal ground effect as the regular jockeys experience are negative of course..sorta like uncontrolled disturbance ( tail authority loss etc ). I have put extra effort to solve all these problems.
     
    Last edited: Jun 17, 2012
  9. Jun 17, 2012 #69

    Starman

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    OK, well it was a secret to me because I hadn't heard of it, and I was keeping it a secret from the people on the boating design forum, since many of them were unkind, to put it nicely.

    If you have the time can you say why some people failed at it.

    Concerning stability, this is what I dreamed up: Essentially a canard. The front wing would be a reverse low aspect ratio delta that is in chord dominated ground effect. The rear wing is a relatively high aspect ratio 'standard' wing which is in span dominated ground effect and it is located quite a bit higher that the front wing. It is like a lot of the reverse delta WIGS you see today that have a high tail, but the rear wing wouldn't be that high. The main difference with my design is that this wing is lifting about half the weight or more. Due to it's longer span it will retain ground effect lift to an altitude where the front wing will have lost it's ground effect lift, causing a corrective nose down force due to the gain in altitude. /the opposite side of the coin, if the craft deviates to a too low position, is that the front wing will experience much greater ground effect lift and raise the nose while the rear wing will not see much difference and will simply trail behind the front wing. In this way the front wing will act like a surface follower and the craft should have automatic stability instead of automatic instability =)

    During flight the relatively long span rear wing will provide good fuel efficiency due to it's long span + ground effect, it would have some wing tip end plates extending downwards to increase span dominated ground effect.
     
  10. Jun 18, 2012 #70

    FlyOver

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    Starman, it is very good of you to try it out yourself to think and build a WIG craft. Don't let the past failure history be your hindrance but learn from the past and make it better. I wish you good luck.

    About Mr Fischer and AirFoil Development, I think they are crazy too. These people never give up. In fact, Mr Fischer has spent his entire lifetime to develop WIG Craft. Now he is 80+ of age, I believe, and still working to commercialize WIG craft. Not only the time that they had spent, but also money. I reckon that they have spend more than a couple of millions Euro.

    Well, only time can tell whether the time and money spent is well spent. If history of any guide, only the strong will survive.

    "The engine for take off uses a water prop which is retractable, and it should be a two stroke for light weight. The poor fuel efficiency of a two stroke won't matter because it will be used for such a brief period. In fact a standard outboard motor could be used for this."

    I suspect that this 2 stroke engine and the air propeller engine will not have enough power to overcome the hump drag (the maximum water drag in speed boat). In fact, this 2 stroke engine will increase the hump drag as it remains under water during take off. Remember, drag increases much faster than speed, which is required for the aerodynamics lift. Therefore, it is very very important to reduce water drag as much as possible during take off. Otherwise, you will need lots of power.

    "Even better would be a small water cooled diesel for maximum fuel efficiency and long range."

    Diesel engine is not very ideal for WIG Craft. it is because of its heavy weight. For Power to Weight ratio, Diesel engine is very poor. There are 3 main important reasons to reduce engine weight as much as possible in WIG Craft. 1) reducing weight will reduce the hump drag and therefore, reduce the take off power requirement. 2) the WIG Craft structure is already heavy as it is constructed to withstand the force of the water. Just imagine moving in high speed over the water. The water acts like a wall, really. After the weight of the structure, the weight of the engine is the 2nd heaviest components in WIG CRaft. 3)WIG Craft is very Centre of Gravity (CG) sensitive. Thus, if you put more weight in your engine, you have to add weight to the other side of CG Point to make it balance.
     
  11. Jun 18, 2012 #71

    davidb

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    Starman, have you considered a hovercraft hull for your design instead of a boat hull? Seems you could use a small secondary engine to inflate the skirt more efficiently than one with a water propeller to overcome the water drag. Yes, that's been done before too.
     
  12. Jun 19, 2012 #72

    Starman

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    Hi David, the Wig design is something I'm not planning on building for the foreseeable future, I just wanted to follow through on some of the philosophy of the design at the stage it had evolved to.

    I have seen the WIG designs with the hovercraft skirt systems and I've seen the hovercraft with the cloth wings added. The Wig designs had a twin hull with a flap in front and back that were lowered to capture the air cushion. This does seem like a good way to tackle the power requirement for take off and if I was going to continue the design it might be worth looking at the twin hull form for that reason.

    There still is a great advantage to a high powered water drive, and that is that since a water prop gets so much 'traction' that it will accelerate the vehicle to flying speeds in a reeeally short distance. This can be beneficial in rough water conditions.
     
  13. Jun 19, 2012 #73

    Starman

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    Hi Flyover, thanks for the encouraging words at the beginning.

    The way I was looking at it is like this, let's say you need around 200 hp to takeoff in your WIG and only 50 hp to cruise. If you have a 200 hp two stroke motor and an 80 hp diesel then it will takeoff fast. 200 hp outboard motors are common enough and don't weigh that much, also they are very reliable and fairly light weight.

    If you only need 50 hp to cruise then you could use a small diesel engine. The new small diesels made for small cars are pretty light, and since you are using such a small engine it will be much lighter than any other engine that was doing all the work of takeoff and flight. Also, diesel is more fuel efficient so for long range (I was planning on long range) the savings in weight of fuel is equalt to the weight of the engine, so in effect the engine weight is free, as if it weighed nothing, when you compare the total weight (engine + fuel) to a gasoline engine.
     
  14. Jun 19, 2012 #74

    orion

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    I'm fighting a respiratory infection now so time at computer is limited - will have to be brief:

    Virtually all programs that have examined the canard configuration have concluded that this is not a viable approach due to adverse issues of height stability. Notice that today, no development (that I've seen) is even considering the canard as an option.

    Long wings are incongruous to any reasonable WIG operation, especially for any craft looking to operate recreationally or commercially. Too much potential for inadvertent contact with water and no substantial benefit to flight effectiveness. Proper WIG design must abandon the thinking of airplane design and really concentrate only on those aspects of extreme low height operations.

    Possibly true. But do keep in mind that much of the work done by Hanno Fischer was done through decades of the German government's funding of the technology. But about five years ago there was an invitational fly-off of the prototypes in development at the time. The craft included the Hoverwing, the vehicles by Jorg, one or two from China, and I forget the rest. In all there were nearly a dozen vehicles present. On the day of the test there was a slight wind and the lake developed a slight chop (a local WIG craft developer whom I've gotten to know relatively well was there) - not one craft was able to lift off the surface. That pretty much killed the government cash cow.

    The water power idea has potential but most that have tried this fail to take into account that transition between the last bit of water contact and flight. There is still quite a bit of drag in this region so if the craft has insufficient power to go on air power alone, as soon as you shut off the water power the craft simply settles back down onto the surface. This is really tricky.

    The hovercraft systems can demonstrate benefits in regards to skin friction but they do not overcome hump drag (bow wave). The HW designs are still dealing with this, along with the skin friction drag of the side walls. Yes, there is potential but not the total solution yet.

    Water power in rough seas is very problematic due to the on and off contact of the water drive system. Very damaging to the components and subject to heavy cavitation.
     
  15. Jun 20, 2012 #75

    FlyOver

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    Orion, it seems that everything has been tried to make a successful WIG Craft but with no success. I believe in that statement given the long history of WIG technology and so many people that had tried to build it but with no success so far.

    I even started to think that WIG is no longer commercially attractive for over the sea transport. This can be achieved efficiently by aircraft with the air tickets getting cheaper every year. It is no point trying to invent something new for the same purpose even though it promises (and unproven) economical advantageous.

    Perhaps, we should try to invent something that provides mankind a jump in technology such as the outer space research, nano technology and zero point energy.
     
  16. Jun 20, 2012 #76

    orion

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    Sadly true - I think there's a variety of reasons for the lack of technological prowess in these programs, most of it stemming from too many ingrained ideas. For instance, Virtually all Russian and Chinese programs are still based on the classic work done by Dr. Alexiev, utilizing rectangular wings. While this does have some mathematical advantages, from the stability and controllability standpoint it is problematic.

    But I think the biggest problem is that too many developers try to approach this technology more as a flying amphibious airplane rather than a new water based technology transport. As long as one keeps thinking "airplane", the WIG concept is going to be mired down with in-optimal approaches that will fail. Oh well, all it takes is a few more million....
     
  17. Jun 20, 2012 #77

    bmcj

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    I would think that trying to design WIG with an airplane mindset opens you up to the risk of getting too far out of ground effect and not having sufficient wing or control to recover properly.
     
  18. Jun 20, 2012 #78

    topspeed100

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    That is exactly why I designed my WIG aeroplane in a manner where the WIG piece in the middle is a lifting body at the same time and wings are out of the ground effect.

    Orion is right..it takes a million..but so does all passenger planes..some might need many more.
     
    Last edited: Jun 21, 2012
  19. Jun 20, 2012 #79

    autoreply

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    Wouldn't the "minimal size" constraint (because of wave height) also be a major problem, you can only be successful if you make a really big one, but then the financial risks are simply too big?
     
  20. Jun 20, 2012 #80

    Detego

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    [h=1]WIG - Wing in Ground Effect[/h]
     
    Last edited by a moderator: Mar 20, 2019

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