New folding cat design

Discussion in 'Multihulls' started by Corley, Oct 7, 2014.

  1. Corley
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    Location: Melbourne, Australia

    Corley epoxy coated

  2. Jim Caldwell
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    Location: Cleveland, Ohio

    Jim Caldwell Senior Member

    Ouch, good thing they were using helmet's.
  3. Doug Lord
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    Doug Lord Flight Ready

    I feel sorry for the designer/engineer and/or builder. That reminds me a little bit of Team Philips when the one bow broke off. On SA, it showed that the thing had four identical foils two forward, two back. Very interesting, but I don't think I get it.......
    pictures-team 50-50 of their 35' racing cat:

    Attached Files:

  4. upchurchmr
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    upchurchmr Senior Member

    Nice looking boat except for that hinge in the middle.
  5. link16
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    link16 New Member

    Hopefully it is salvagable, all that time gone...
  6. Fanie
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    Fanie Fanie

    I was hoping to see something sensible.
  7. Mike Nickerson
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    Mike Nickerson Junior Member

    Looks like the bi-plane rig did take the load off the main cross beam (it is still in good shape)... bad news the hulls weren't up to the load.
  8. groper
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    groper Senior Member

    Ah... That's the first time I've noticed the foil arrangement... So they are using a tandem foil configuration ? Interesting.... I was considering using 4x equal size C foils on my boat, also a tandem config. I was reading a paper the other day, can't remember the link, and it showed the CoG stability window for 3 typical foil config -canard, aeroplane and tandem. There wasn't a huge difference between them, canard had the widest stability window, tandem 2nd and aeroplane slightly narrower again. It was also shown that the downwash from the front foil didn't significantly effect stability, only the rear foil needed a higher AoA to compensate for the downwash flow angle.

    I liked the configuration for other reasons however.... I believe there would be higher pitch dampening with foils further apart and closer to the ends of the ship in a tandem config. Particularly the front foil, closer to the bow i would think should offer a further reduction in pitch accelerations. Do you have a link to information or research papers on pitch motions of various foil configurations and the effects on improved sea keeping motions?
  9. Doug Lord
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    Location: Cocoa, Florida

    Doug Lord Flight Ready

    I was taught that the "airplane" configuration with 80% of the load on the main foil, with +2.5 degrees AOI on the main foil , and zero degrees* on the rudder foil was the best set up for excellent pitch control. That and half the area of the main foil or foils for the rudder foil area, so that it is more lightly loaded than the main foils. The new configuration I'm testing on the model has the best pitch control I've seen yet because the unloaded mainfoil works with the rudder foil to control pitch.
    I haven't studied them at all , but the new "C Fly" cat appears to use a canard arrangement for a foiler they claim will have superior characteristics in a seaway.
    * relative to the static waterline(parallel to the flight waterline sometime after takeoff)

    PS- the distance between the quarter chord of the rudder and main foil is important-if you follow the 80% load on the main foils rule that usually results in a long "footprint".
    However, if you compare the footprint of my test model with any catamaran footprint the model is longer.
    This is from my thread:
    The Fire Arrow has a "footprint" equal to 61% of its overall length. But in comparing this measurement with full size catamaran foilers I've found:
    1-AC 45-42%
    2-AC 72#1-43%
    3-AC 72#2-45%

    PS the documents below are all I have-ones about power multihulls. But there is plenty of other stuff out there:

    Attached Files:

  10. groper
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    groper Senior Member

    Thanks Doug.

    I didn't mean pitch stability , II was referring to pitch accelerations experienced by the people on board. Ie the sea keeping motions in a sseaway. I would imagine these motions are improved with the longest possible footprint. The big Russian hydrofoil ferries seem to be quite long, and Dr. Matveev wrote a paper about tandem foil configurations. His Olympia class ship seemed to have the best sea keeping ability of them all and it was a classed as a tandem if I'm not mistaken? Full foiling in 3m seas is pretty impressive.... wish there was a video of it somewhere....
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