Hydrofoil assisted or full flying kayak

Discussion in 'Boat Design' started by Canoemaker, Dec 19, 2009.

  1. Canoemaker
    Joined: Dec 2009
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    Canoemaker Junior Member

    dont get me wrong your ideas are probably sound but i am making a kayak not any other human power boat and this is sort of like making a racing bicycle and you are suggesting recumbent bicycle that has many advantages but is also severely limited in other terms and you wont ever see them doing tour de france

    By open category boat i ment open category kayak or canoe unrestricted by ICF or any other governing body limits but still has to be ither kayak or canoe

    I am just looking if there are ways of gaining some speed in ways outside of the basic hull design that is already close to what it can be done and only small incremental gains are possible. This foil assisted or foiling concept might be more applicable to sailing kayak or canoe.

    here is a sailing kayak built on one of my kayaks by a friend of mine www.viroga.com in future we might try covert the OC-1 for sailing
     
  2. Guest625101138

    Guest625101138 Previous Member

    The advantages of recumbents cycles are well known. They do not race at elite level because they have been banned. It is the same with sliding riggers in rowing sculls. These are historical constraints that ban radical developments because there is too much invested in the current technology.

    Irrespective of the position with bikes, the advantages of pedalling are more extensive in a boat. Recumbent bikes and upright bikes are both pedal powered. The only advantage of a recumbent bike is the lower windage. There are not many hand powered bikes. If you were going to run or cycle a race on land would you seriously consider doing it on your hands.

    Rowing uses leg muscles but if you really think about it how dumb is it to face backwards when you are the pilot as well as the engine. Rowing is only really suited to straight line courses or operating with a compass on longer ocean events.

    If you are permitted to race a pedal powered boat then you should give it a go before you dismiss it as not offering a significant advantage.

    I am permitted to race in the unrestricted division of a 404km marathon event and my pedal powered boat does well against a wide variety of craft despite my interest being primarily the engineering rather than fitness or racing. I have a good understanding of the relative performance of other boats.

    Ships gave up paddles over a century ago in favour of more efficient and effective propeller propulsion. If you want to just go faster on water, and there are no arbitrary rules restricting what you are permitted to use, then explore pedal power before getting into foils.

    If you know what power you can sustain in a recumbent position I can give you a calm water performance estimate within about 2% of what you will achieve in actual.

    Rick W
     

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  3. Canoemaker
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    Canoemaker Junior Member

    Kayak competitions,marathons and triathlons and multisport(mostly include some level III WW) events only allow kayaks and canoes on some races even sculls but so far the rowing boats are not doing well and even so kayaks canoes and sculls would fall in separate categories on the same race.
    I am probably also biased towards kayaks and canoes and come from paddling background ,and really wouldn't consider anything else.
    I personally only paddle canoes ,an they are even less efficient and more difficult to master than kayaks but its a choice that might not be rational but maybe more romantic and for 99% of paddling its just for the fun of it.but that doesn't mean that we have to use wooden boats(i do have a 50's wooden canoe lying round awaiting renovation) ,i always try to design & build best possible designs in many different sports from agile slalom ,downriver racers,flat water racers or fast marathon runners. But canoes also have great tradition and people crossed and still do almost every expanse of water in them.
    Canoe tribe: ''half the paddle,twice the man''

    But back to the subject i am now on the look out for a good low speed foil section for my application ,from there i can do more calculation and more likely than not try out some wild concoctions using one of my 2nd quality kayaks( built out of basalt fibre vacum infused vinlyester) that has been lying around for a while and can be cut and modified.

    Is that pic from murray red cross 400+km marathon,so where are Rambo and Clarkie in their OC-2
     
  4. Chris Ostlind

    Chris Ostlind Previous Member

    There simply is not enough power available from a human being, even a really fit one, to provide the necessary thrust for more than an hour, or so. This boils it all down to a purpose designed hull that is optimised for the target speeds as well as a really well made prop and drive system that is powered by pedals.

    One will never be able to create an arm/torso powered boat that will last as long as do leg muscles, or generate as much power.

    Leave the foils to the guys who have well-made sails and/or internal combustion engines and are willing to sign-up for the extra fiddle factor associated with the form. Foils on kayaks and stepped hulls with all of the ordinary drag signatures are Red Herring bait.

    I like that you're wondering about it, Canoemaker, but it's not going to go anywhere with current human physiology. Things might change in 20,000 more years of human evolution, but it's not here now.

    Ricks' comment about the tiniest bit of weed, or crap in the water, that finds its way onto the leading edge of the foils is as poignant as it gets. Some folks really want to have foils on anything and everything, not recognizing that they just are not appropriate for most cases. Same is true for stepped hulls.
     
  5. Canoemaker
    Joined: Dec 2009
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    Canoemaker Junior Member

    That is the reason i first only considered foil assisted instead of full foiling concept ,here foils would only provide part of the lift to reduce wetted surface,also such concept in theory allows for more or less power vs more or less all or nothing fully foiling boat. Also am not trying to compete with other human power boats only kayaks and for well defined speeds.
     
  6. Chris Ostlind

    Chris Ostlind Previous Member

    Then it's very simple.

    Do you get more than you pay for the whole experience. That includes seriously sluggish performance at sub-lifting speeds, shallow water collision issues, draggy things on the foils, the need for knee-deep wet exit/entries for any use period and the whole tamale. Maybe you can partially overcome the wet entry business with sliding foils in cassettes, but now you've added weight, and complexity to what is an otherwise simple and elegant boat. The spiral is wicked and unforgiving.

    The forum's esteemed, Tom Speer, has noted that if the payback in reduced drag does not exceed four times the drag induced from the appendage, then it doesn't pencil... and that's just from the lift perspective. All the other issues still remain.

    I don't see it working in this realm compared to the aggravation of it all.
     
  7. Guest625101138

    Guest625101138 Previous Member

    If you want to do some calculations then you can work on a lift to drag of around 20 for a well designed foil configuration to suit the application.

    At 6.5kts the lowest drag hull, with total mass of 950N, requires 38N thrust. So the drag for weight is 25. In this case there is no advantage going to a foil because any additional lift will cost more than the hull in displacement mode.

    If you have a length constrained boat, with say a mass of 800N and the drag exceeds 40N, then you might find a point where foil assist will reduce total drag. But as noted above the boat is already sub-optimal.

    The easiest way to assess foils is to use JavaFoil - just google it and run the applet. Attached shows what you can get from a 5% thick 16-series foil at Re# 100,000. You need to do some initial design to determine the Re# but I expect it will be around 100,000.

    As you can see the best L/D here is 26. I selected this as something that was practical to make. You can go higher aspect but you need to consider bending loads in the foil. There is no strut drag or wave drag in this calculation either. You can reduce wave drag be setting it deeper in the water but then the strut drag goes up.

    Even with partial lift there are problems with changes in trim. A thin foil will be quite sensitive to trim changes so you may have to go thicker to get more tolerance to trim changes.

    If you know the drag on your hull at the target speed then you can do some quick calculations to determine if you are likely to get benefit from a well designed foil assist set up. The foil needs to be around 3 chord lengths deep to get wave drag out of the equation. There could also be a slight positive from the buoyancy of the foil and strut. This becomes more significant if you simply want to foil at lower speed.


    If you do not know the drag on the hull then there are various ways to calculate it accurately.

    Rick W
     

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  8. Guest625101138

    Guest625101138 Previous Member

    Yes from 2008.

    Attached is the only OC2 I can recall. The photo was not last year but 2006. The boat also raced in 2008. The same driver, with the Red Cross bib, raced a much shorter open twin canoe in 2005. They start in a later time slot than me each day in the OC2. From memory they caught me on the first day last year. Each day is like its own race with the same starting groups.

    There are over 200 boats compete and they start in groups of about 20 to 30 boats depending on expected time to finish to avoid congestion in the narrow river. The previous series of photos was the last day of 2008. It is a relatively easy day around 75km. I was in good shape after the first four days so set the pace in my group. I can pull away from all but elite paddlers if I really go hard but it saps a lot of energy. In the photo I am doing 14kph over the ground and about 12.5kph through the water. After the start I settle into about 11kph through the water if weather is calm. I wane after about 4 hours and taper to holding above 9kph through the water at the end of the 90+km days.

    The organisation and fundraising has been taken over by YMCA this year so it is no longer a Red Cross run event. Red Cross did it for 40 years.

    Rick W
    EDIT: I checked my plot for the day. Actual speed over ground at start was 15.8kph. Through the water is about 1.5 to 1.7kph slower. I backed off once heart rate got to 140bpm. Overall GPS average for the 73.7km was 10.99kph over the ground.

    There was an OC2 with a pink deck in 2008. It was #6.
     

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  9. Guest625101138

    Guest625101138 Previous Member

    Attached is a photo of the OC2 with pink deck. This is at start of Day 3 and shows most of the boats in my start group coming down to the start line. The OC2 would be in the next group 15 minutes later because they are already on the shore. They would launch as soon as my group clears the start line.

    Rick W
     

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  10. Canoemaker
    Joined: Dec 2009
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    Canoemaker Junior Member

    Rambo and Clarkie set the open record in 2007 with time of around 32h.26m and on handicap 26h14m the placed second.WTF is this handicap.The boat had a black foredeck(516) but the guy standing over it not one of them.the pink boat was i think some 30min slower on handicap.

    The foils i am looking for will have thickness above 14% ,first sort of worst case calculations we did with a basic Clark Y foil in very blunt configuration(one 500x100mm wing) so that we can see if there is any merit to the concept(in real configuration we would use very high aspect ratio foil),it showed that 1 knot increase is possible,due to drag reduction of 7N,i have looked at both 6412 and H105 sections that are used on moths but these are better used on faster craft.I need something more suitable for low speed use.
    I think we could with more optimal foil achieve even a bit better drag reduction ,and you know for shorter races where more power is to be had even a bit more
     
  11. Guest625101138

    Guest625101138 Previous Member

    You have a very draggy hull or are overestimating the benefit of the foil if you are showing an improvement of 1 knot. How are you determining the wave drag on the foil and what is the foil aspect ratio? I doubt you will get better than L/D of 15 with a realistic size foil using a Clark Y section.

    I did not look at many options but I doubt that you will do much better than the 16-series I posted earlier.

    The Clark-Y data is attached but even this will be optimistic because the higher lift coefficient means it will be shorter and the RE# will be lower. In these low speed range the Re# is a significant factor.

    With regard to the MM handicapping there are boat and age allowance. Outriggers canoes are recognised as being quite slow so get a good boat allowance. I race in the unrestricted class so no boat allowance but I do get an age allowance.

    Rick W
     

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  12. Canoemaker
    Joined: Dec 2009
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    Canoemaker Junior Member

    hull is as slippery as they come but i admit that the drag analyis of the hull on reduced displacments might be flawed as the software probably doest handle thin long hull very well. (base displacment is 87kg and the we looked for foils providing,27,51 or 70kg of lift) .For the foils we for starters just calculated a simple clark y foil using javafoil ,first we just too a huge 1m foil and looked at the numbers and then shortend teh foil but didn't design any proper hi-aspect ratio foil yet as we are still looking for a goo foil section ,as i said this are very rough calculations.
    I can send you more detailed calculations we used on your e-mail .Can you run the naca6412 as i cant seem to get much usefull for if from java
     

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  13. Doug Lord
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    Doug Lord Flight Ready

    ============================
    Do you mean 63412-that is the foil originally used by John Ilett on the Moth? You might find some useful info in this paper:
     

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  14. Canoemaker
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    Canoemaker Junior Member

    Yes Naca63412
     

  15. portacruise
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    portacruise Senior Member

    Weed and trash in the water is a more significant issue for props than for paddling. At some point you have to stop completely (0 km/hr) to untangle or at the least, lift up in the air to fling off debris on the prop. This is more pronounced with props on long trailing flex shafts, as there is a tendancy for floating and suspended debris to be gathered up and funneled into prop as the boat moves forward. This effect is more pronounced than in a vertical shaft troll motor. I am tinkering with a counter rotating feed screw flex shaft which may help but not completely eliminate the issue. In the mean time the best approach I have used is to lift the shaft above the water surface where the increased speed flings off debris in most cases.

    Special surfaces have been tried on displacement hulls which might give the slight advantage 'noe maker has been looking for.

    Porta





     
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