Fire Arrow Advantages scaled up to 19.5' LOA
I'm trying to come up with a relatively short but complete description of the advantages inherent in the full size version of the Fire Arrow design. This is another improved version:
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The full size version of the Fire Arrow at 19.5' would have a beam of 22'. It would fold to be trailered.
This beam would be impossible without the foil system described below:
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Probably the most significant feature of the Fire Arrow is that it uses two completely independent altitude control systems for the first time on any trimaran:
1) UptiP ama foils(also a first for any size trimaran*) that control the height of the ama above the water,
*used on this boat way before they were used on any other tri.
2) Wand controlled mainfoil on the daggerboard-controls main hull height above the water which, in turn, sets the angle of heel for the whole boat.The mainfoil also allows the main hull to fly in very light air.(5mph)
But its the interrelationship between the main and rudder T-foil with the ama foil that makes the system so significant. The rudder T-foil is a trailing foil and "follows" the main foil. Altitude and angle of heel for the whole boat are set by adjusting the wand length. The angle of heel can be set between 10 degrees and 17 degrees. The boat is extremely stable in pitch because of the bi-foil arrangement on the main hull-the daggerboard foil and rudder foil always work together to control pitch when the boat is foiling. But they also control the ride angle and pitch of the ama foil which can't pitch on its own-in other words the ama foil can't all of a sudden "go negative" and cause a pitch pole.
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3) A major advantage of the wand controlled mainfoil is the ability of the wand to cause the foil to create downforce which can add significantly to the righting moment of the boat. It is an automatic response to the boat heeling even a slight amount: the wand will cause the flap to go up as much as is necessary to restore the main hull to its designed flight altitude. That can add a large amount of righting moment to the boat.(40-60% of boat weight or a bit more)
The use of foil downforce has been well proven on the Trifoiler ,Rave, Skat and Osprey. And the drag caused by doing this is not as much a disadvantage as the extra RM is an advantage.
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4) Two Stage ama(see pix below) : the ama hull is attached to a "curved piece" that adds to the ama buoyancy in knockdown conditions. This "two-stage" design allows for a small planing hull with relatively low drag during incidental contact with the water but provides tremendous buoyancy during a knockdown-enough; combined with the high dihedral crossarm structure, to prevent a capsize in most conditions.
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5) Oversquare platform: the boat is 1.22 times as wide as it is long. A "normal" tri with that much beam would need at least 15mph of wind to be able to fly the main hull. But because of the wand controlled main foil, this boat will fly the main hull in as little as 5 mph of wind which opens up the effective wind range for the foiling system-way beyond most multihull foilers.
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6) Light Air Foiling: from a marketing perspective selling a foiler that only starts to foil in 10-15mph of wind is a mistake but that has been true of many multihull foilers. More and more boats are targeting starting to foil in lighter winds: The Whisper foiling cat and Quant 23 are examples of foilers whose designer/builder has made the commitment to start flying in light air. The Fire Arrow test model was designed to begin to foil in a 5mph wind 5 years ago and reached that design goal on July 24, 2014. The full size version will take off in about the same wind speed.
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Hopefully, I'll be able to get the help I need to build a 19.5' version of the Test Model which would be a very cool trimaran and would illustrate well why this system is such an advance in small trimaran design.
In the meantime, I'm planning on getting more video with the reefed rig and shorter mainfoil and rudder foil.
