HERE WE GO AGAIN !

Discussion in 'Bush / Float flying' started by tunnels, Sep 25, 2015.

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  1. Sep 25, 2015 #1

    tunnels

    tunnels

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    FOILS ! seems no one is interested or they have there fingers in there ears or even there heads buried in the sand !!
    Yes there could be advantage of foiling and getting the wetted surface to an absolute minimum but unless you take notice of what's going on in other fields and do some copy and paste of information its going no where !!
     
  2. Sep 25, 2015 #2

    tunnels

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    If borrowing technology and knowhow from some where else to learn from then that's what's needed to make things happen !!I have done it many times !! adapting ideas to make other things work better Composites is no different ! The manufacture of foils had had to go to a whole new level of thinking and the foils shapes used has also been and is still being explored to find the optimum for different application's The actual shape that's being used takes a lot of getting one head around as to the reasoning
     
  3. Sep 25, 2015 #3

    Tiger Tim

    Tiger Tim

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    I thought for airplane speeds skis were where it's at. Don't foils cavitate and do all sorts of awful things above a certain speed?
     
  4. Sep 25, 2015 #4

    BJC

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    Nope. Everyone knows that a properly designed tunnel hull on a flying boat is better than any other alternative. I'm pretty sure that I read that here on HBA from a tunnel hull design expert.


    BJC
     
  5. Sep 25, 2015 #5

    bmcj

    bmcj

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    Insanity: doing the same thing over and over again and expecting different results. -- Albert Einstein. ;)
     
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  6. Sep 25, 2015 #6

    Topaz

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    Moderator Note: Much as I completely understand the impulse, it's best simply not to reply, rather than mock.
     
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  7. Sep 25, 2015 #7

    bmcj

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    P.S. - Tunnels, I'm just having a little fun. I think an open and objective discussion about tunnel hulls is very appropriate for a forum like this.

    (Unfortunately, I don't have any knowledge or experience from which to contribute to the discussion.)
     
  8. Sep 26, 2015 #8

    tunnels

    tunnels

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    Ok lets get some basics sorted right at the beginning , Catamarans and tunnels are as different as chalk and cheese in there design and performance ! Cats sure will handle some rough conditions but have some really bad habits . They are much more stable and ride much better than a ordinary mono designed hull . A tunnel is steets ahead and yes has twin hulls but that where the similarity ends ! Tunnels at rest are more stable , they are quicker off the mark and on the plane and are softer riding !! A cat does not make any use of the area between the hulls and in some cases its the spacing of the hulls that kills the cats performance ,where as the tunnels uses this area and its where its performance comes from !! The cushion of air between lifts the hulls and raises and holds it partially or completely above the surface of the water as speed increases and water friction diminishes quickly !! Yes they used to flip over backwards because Aerodynamics was playing a huge part and no one was aware of just how much influence it really was having !! . So the deck and above the water design was very slow to catch on to all this even when lives were lost and the boats were flipping because of the higher speeds being reached with bigger motors and better hull design improvements !! They living in the phenomenon of surface effect that had never been realized or considered and for me it took a visit to an amateurs inventors meeting to learn about it . So aerodynamics and hydrodynamics had to be bought together as these BOATS had to FLY !! And fly they do ,yes only the lower part of the outboard and the propeller were all that was in the water ! Race boats were the proving grounds and where design became vitally important to restrain this beast that was rapidly emerging!
    Tunnels had always fascinated me how it all worked!! I had the privilege of an elderly friend that had been a chief fight engineer for Air new Zealand a good part of his life and we spent hours and hours talking ,drawing ,and coming up with why tunnels worked and do what they do and ways to improve them !! Scott Robson is the only designer in nz that had listen to Ian and experimented and designed his boats using Ian's ideas!!I became the fiberglass workshop foreman for building Scotts small but fast tunneled hulled family boats!, these boats were absolute magic and were way in advance of any other boat I’d ever made or used in my whole life ! This was my place to be and I learned everything I could absorb and even dabbled with small race boats as well. At a meeting quite recently i was asked about my thoughts and ideas of making and improving an amphibian plane ,that was really easy and didn’t have to think to hard about it !, there was nothing else to consider other than a tunnel hull !! Its streets ahead of anything else anyone has thought about! Ahh but a point to remember that’s really important is not all tunnels are the same and what i have learned about them i have not seen done anywhere except boats designed by Scott Robson ! . The old thing of taking photos and then studying and drawing out the things you see then analyzing each and every detail in depth is really important so you are able to understand more and know what works and why and most important how it works !! Dead rise angles , lifting strakes and what width would be best suited !! planning flats along the bottom of the hulls and small reverse angles on corners to eliminate crabbing and causing alarming behavior if the hull is landed at and an angle or even in a nose down diving situation !! Building rocker into the bottom to assist with the (plane) hull rotating during takeoff and landing! Does away with having to have a step!. The inside of the tunnel is where lots of tricks play a really important part as everything that’s there is needed to create lift , eliminating water spray from going everywhere and reduce skin friction ! The latest and greatest developments in hull composite construction and design is flexing, cushioning hull panels that give a much softer ride !! This something I started working on and developed myself more than 25 years ago for surf life saving . Helping the people to get there job done quicker and easier and not get seriously hurt in the process . Now its a hot topic with the army and navy assault craft carrying troops at high speed in rough conditions and everyone arriving on the beach ready to fight !! There’s millions of dollars being spent on ideas and development of these types of water craft!! So that’s me in a nut shell !
     
  9. Sep 26, 2015 #9

    Tiger Tim

    Tiger Tim

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    Thanks for some name dropping, it helps with the Google search. Is this beast your handiwork?
    [​IMG]
    I'm not a boat guy, but I want one!
     
  10. Sep 26, 2015 #10

    bmcj

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    Does it one with all of the accessories shown in he photo? :gig:
     
  11. Sep 26, 2015 #11

    mcrae0104

    mcrae0104

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    Yes, but it's a very high maintenance package.
     
  12. Sep 26, 2015 #12

    Topaz

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    Trust me, you can't afford that. :gig:
     
  13. Sep 26, 2015 #13

    Starman

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    Ya, twin hulls are where it's at, but you could just throw away the bathtub between the hulls and call it pontoons.

    Just kidding. If there was only some way of streamlining the center part and making it into like, a wing. :whistle:

    Ground effect works better with more span between the hulls and you need that because you need ground effect at slower speeds than those boats use.
     
    Last edited: Sep 26, 2015
  14. Sep 26, 2015 #14
    Nice ducted fan, stub wings & a tail and it might make an interesting Ekranoplan.
     
  15. Sep 27, 2015 #15

    tunnels

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    Its the tunnel between the hulls that's the key !! You are missing the point !! the hulls lift the boat at low speeds and when the speed gets to 50 mph plus then the air starts to take over and lift even more and so speed increases very quickly ! 70 to 80 mph and significantly the air had a lot of lift not only under the boat but also the vast existent of deck area produces quite a bit of lift as well !! To design a stable fast boat first you have to choose a foil to work with then superimpose the boat over the top retaining as much of the actual foil shape for the underside (tunnel roof ) and the upper parts as well !! simply it has to fly !!
    No the boat in the picture was after time working with Scott but its the copy of a boat I wanted to make myself !!
    If the boats wont reach 70mph plus I wasn't interested !!speed on water is something else !!
     
  16. Sep 27, 2015 #16

    mcrae0104

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    And all of this has what to do with airplanes? Connect the dots, please.
     
  17. Sep 27, 2015 #17

    tunnels

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    If you read and couldn't connect the dots then you have a problem !!

    My latest thoughts as mentioned some time ago is to also look seriously at adding a lifting foil between the two hulls just slightly forward of the cg to assist with getting up on the plane even quicker and having a shorter take off and possible a much shorter landing !! Im not even going to contemplate the idea is one of those skinny little foils like everyone is hooked on that relies on being fully submerged to make it work !! that's a no brainer and not worth a second thought ! It would be a wide section that is capable of actually planning along the surface at landing speed and holding the whole hull partially up out of the water !and only need one foil not two or more !!
     
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  18. Sep 27, 2015 #18

    mcrae0104

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    It was a legitimate question; no need to be condescending. The idea of using a foil between two hulls is interesting and may have merit. Why don't you build some models and test them?

    This is not intended as a personal attack, but frankly, even if we leave the grammar issues aside, your communication skills are marginal. You should expect people to be confused by your ramblings and pontifications.
     
  19. Sep 27, 2015 #19

    Starman

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    Well I can see you're all excited !! and no I didn't miss your point, a tunnel hull could help, in fact I've drawn tunnel hull based aircraft before you were old enough to, um ... I was just mentioning where the idea is all --ed up and stuff. Like for instance, thats too fast to be useful if you are going to use it for most homebuilt airplanes, including bush and float planes.

    There's this great new invention called surface piercing hydrofoil. The idea of a foil like some kind of wing is all --ed up too. A surface piercing hydrofoil is shaped like the bow of a speedboat so your 'foil' ahead of cg would look exactly like the step on an aircraft pontoon. Gosh, I guess someone already thought of it.

    There's this other little detail, the tunnel uses ground effect, but the wing already does that and its much wider, so you want a fast biplane, am I right? ... yaahahaha

    Well with wing like foils underneath it would be a triplane ... yaaahahaha

    ... otherwise known as stick in the mud. If you try to touch down with those mini wings when they hit the surface you will flip over.

    Have fun.
     
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  20. Sep 28, 2015 #20

    tunnels

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    Long Narrow and skinny hulls and wave piercing for this type of use will give you almost nothing at all that's useful ! Has very little if any lift !! has to be long and deep to give enough buoyancy and will sit way down in the water ! the wetted area is massive ! so why even bother ??and you would be missing out on the lift produced by the twin hulls and all the flat strakes and planning areas the tunnel roof etc and by adding a foil (not a wing ) there's even more lift I could imagine the hull producing enough lift at close to 30mph that its sitting on top of the water and waiting for the planes wings to give enough lift to finally become airborne and begin to fly !
    Yes a model is quite on the cards in the very near future for sure !! I have been away in new Zealand for the past 6 months but have come back to china just 5 days ago to resume my life and hopefully start working again !!
    To me there is no reason to have any part of the hull or the plane that is not going to provide lift and make it easy and streamlined so its stable in flight or on the water ! And as for nose diving it would never happen even if you hit the water at 45 degrees because the front of the tunnel is quite big shaped to collect air and force it down and under the hull !there is enough hull in the bow sections to prevent it wanting to skew off at an angle or broach and do all the crazy thing mono hulls love to do !! and at slow speed I have seen some amphibians with there bow waves coming right up over the front back to the windscreen !!! All that water will be retained and directed Under the hull again producing lift even at very slow speeds !!
    After years of making racing and using tunnel boats I have never once ever had one single scary moment ever !! side on the rough water just rolls under and the minimal hull movement , bow on in big seas they behave like a jet ski and the faster you go the more fun they are !! a momo and a cat will pound and bash and thump into the waves ! The tunnels just lands softly and theres no pounding or bashing !
    For a tunnel hull use on a plane coming into land I would say you wont even feel a thing when it touch's the waters surface and a choppy surface with waves up to a foot or two feet high tunnels love those conditions and thrive on it !!
     
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