High Performance MPX Foil/Self-righting Trimaran-The Test Model

Second Volvo Inshore Foiler with technical information: New Catamaran Foilers https://www.boatdesign.net/threads/new-catamaran-foilers.51898/page-6#post-818445
One technical innovation from this boat is a center lifting foil!!

 

Fire Arrow Righting Moment: Maximum Righting Moment for the Fire Arrow has three components--
1) Righting Moment due to the weight of the boat,
2) Righting Moment due to the weight and placement of the crew,
3) Righting Moment due to downforce from the main foil
4) I assume some degree of knowledge about boat design, particularly small boats, but the moments are about the center of lift of the lee ama foil which I assumed(wrongly, I guess) would be self-evident.
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1) and 3) have the same righting arm. 2) has a longer righting arm since the crew sits on the windward side of the cockpit.
Sketches #1 and #2 show the components of the maximum righting moment for Fire Arrow, which occurs with the boat flying and the mainfoil developing downforce. They are not meant to be precise or to scale-simply illustrative.
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Downforce may be hard to understand for some because what isn't shown in the sketches is the LIFT of the main hull due to wind pressure on the rig*. As the boat begins to fly the mainfoil is unloaded due to this pressure. Just before downforce begins the mainfoil is at zero lift. Lift on the main foil is automatically controlled by a wand surface sensor. As the wind pressure increases the boat heels a bit causing the wand to reduce the down-flap angle until the flap reduces the foil lift to zero (this is the designed flight angle of heel of 10 degrees). Downforce is caused when the wand raises the flap above the no lift point(due to a small increase in the angle of heel from the 10 degree point to about 12 degrees). At the no lift point, the mainhull is entirely supported by the wind pressure on the rig. As wind pressure on the rig increases further the wand causes the flap to rise which generates downforce.
*The mainfoil can lift the main hull BEFORE there is enough wind pressure to do so.


Sketch #1


Sketch #2

 

WOLF daughter of fire arrow-- Installed the forward seat fairings and the aft seat drains:

 

WOLF daughter of fire arrow-- made mast step from carbon tube:

 

WOLF daughter of fire arrow-- mast step installed:

 

WOLF daughter of fire arrow-- Got the rotating wing mast stepped for the first time. There wasn't much light but I took a couple of shots anyway.
PS-mast will probably get a single diamond spreader.....
Happy Thanksgiving!

 

WOLF daughter of fire arrow-- I've been studying this thing to try to come up with a solution for the upper seats that provides the extreme comfort that is a major element of this design. I haven't ruled out the combination seat/tramp that I mocked up earlier but I thought I'd see how this worked visually and then weight wise. Seems like it would work well.
One thing that works particularly well is folding the seats as shown. When the ama is folded it will fit right over the folded seats. The concept needs study.....

 

WOLF daughter of fire arrow-- Finally bright sun! Mast with foils and lower seats:

 

WOLF daughter of fire arrow-- Wolf and MPX-12-father of Fire Arrow:

 

WOLF daughter of fire arrow-- sail patterns for study--217 sq.ft. :

 

WOLF daughter of fire arrow- more shots with "sails":

 

F3 in Model Yachting (again)-but unfortunately not flying as she was the first time(2003) ! I've written to the new owner --maybe I'll hear back....

 

Fire Arrow Foil System:
Gitana 17 , designed and conceived by Guillaume Verdier . A happy coincidence that the basic concept is similar to the Fire Arrow Foil System. Gitana 17 is the FIRST full size trimaran ever to be designed from scratch to use this type of foil configuration:


Maserati- the very first fullsize trimaran to use a foil configuration similar to the Fire Arrow Foil System. The configuration was applied to an already existing MOD 70 trimaran by Verdier :




Fire Arrow- the very FIRST trimaran of any size to use the basic Fire Arrow Foil System:

 

Sad news in the multihull world-Ian Farrier has passed on. He was generous with his time and encouraged me over the years -it's so damn unfortunate!
Ian Farrier has passed on....... https://www.boatdesign.net/threads/ian-farrier-has-passed-on.59565/

 

Fire Arrow Foil System--Downforce =Windward Gain
NOTE-daggerboard is at zero degrees AOI while ama foil verticals are at +3 degrees AOI :
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