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

WOLF---daughter of fire arrow

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Thanks for the ideas.

 

WOLF---daughter of fire arrow / Concept Model

Decided to change the cross arm dihedral from what you see in the picture below to just slightly more than the Fire Arrow. Relatively high dihedral is important for a couple of reasons. Since the boat uses UptiP ama foils the relatively high dihedral allows the boat to tack and gybe without having to lift/deploy opposite foils during every tack or gybe as is done on AC cats, Maserati and others. Reduces crew workload considerably. Also, the relatively high dihedral coupled with the two-stage ama make it very hard to capsize the boat.
After studying this first dihedral and comparing it with the Fire Arrow, I've decided that the dihedral below needs to be reduced to be closer to Fire Arrow but still a bit higher than Fire Arrow. This is too high:

 

Fire Arrow Foil System

For the record the Fire Arrow Foil System was used first on the Test Model and then on Maserati and next on WOLF and can allow these features-not found together on any other trimaran anywhere at any time(so far) :
(added #10 3/10/17)

1) actively controlled main foil-dual wand control on Fire Arrow/WOLF. Maserati controls the AOI of their mainfoil manually. Advantage is main hull altitude control and controlled angle of heel (about 10 degrees on the Fire Arrow/WOLF)as well as ride angle control of the lee uptip ama foil. A big advantage of the Fire Arrow Foil System is that roll attitude is controllable on both boats and can be configured for level flying or flying at an angle of heel by simply adjusting the flying altitude of the main hull.
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2) UptiP ama foils. Maserati has only one foil that works like an UptiP foil but will install a second at some point. Advantage is automatic ama altitude control with no moving parts. The Fire Arrow Test Model was the first trimaran anywhere to use uptip ama foils. These foils allow automatic altitude control of the ama with no moving parts.
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3) Rudder T-foil(s). The Fire Arrow Test Model and the new WOLF use a single rudder T-foil whereas Maserati uses two.
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4) Dual altitude control systems on Fire Arrow/WOLF and Maserati. The ama foils and main foil use two different types of altitude control simultaneously.
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5) The Fire Arrow Foil System can allow a trimaran to develop downforce on the main foil which increases RM and can allow automatic gust response. It can also allow the WOLF ,15.5' version of the Fire Arrow to be sailed singlehanded in up to around 20 knots of wind with no reef.
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6) The Fire Arrow Foil System allows an oversquare trimaran platform to take off in very light air.
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7) The Fire Arrow Foil System has increased pitch control authority compared to a "normal" tri.
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8) The Fire Arrow Foil System allows the mainfoil to begin to unload right after takeoff reducing induced drag.
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9) The Fire Arrow has pioneered the concept of a Two Stage ama--the ama planing hull and the "curved piece".
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10) High crossarm dihedral coupled with the two stage ama and a designed flying angle of heel of 10 degrees on Fire Arrow/WOLF eliminates the need to raise/lower the uptip ama foils with every tack and gybe as must be done with other boats using uptip foils.
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11) The Fire Arrow oversquare platform allows the crew to sit comfortably on the side of the cockpit without having to sit out on the ama while still having more RM than any current production trimaran her length.
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12) The boat may be able to be configured to be 100% self-righting.
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The differences between Fire Arrow(WOLF) and Maserati are specifically related to the size of the two boats and the mission of the boats. Both boats use a virtually identical foil configuration for entirely different purposes: The Fire Arrow(WOLF) is a small sport trimaran that maximizes light air takeoff and ease of handling for one to two people and may be able to be self-righting with no crew action required. Maserati is a fully crewed ocean racing trimaran.
The Fire Arrow Foil System is a revolutionary foil configuration for trimarans from very small to very large and is capable of being configured for different missions while retaining the unique qualities of the System. Maserati and Fire Arrow(Wolf) are the only two trimarans in the history of the world to have ever used this system-but not the last.

 

Fire Arrow/ Wolf Dihedral

This picture shows the minimum dihedral on Fire Arrow which occurs with the main hull static at a bit less than a 10 degree angle of heel. The important part is that the foil on the high ama is nearly clear of the water when the boat is not moving. The Wolf may have a bit more dihedral because it has movable ballast(crew) whereas the Test Model does not:

 

WOLF---daughter of fire arrow / Dihedral

Big change today after lots of studying: rather than change the crossarm dihedral I have changed the "curved piece"(see top pix of unchanged curved piece) in such a way that it lowers the ama hull the same amount it would if the dihedral was changed. The reason is that the high dihedral crossarms(more than Fire Arrow) allow the angled, super comfortable, seats to fit in to the whole assembly better than with lower dihedral. Also raises the center of buoyancy of the "curved piece" to aid in preventing capsize.

 

WOLF---daughter of fire arrow

I looked at the foils from my first foiler today and they're in pretty good condition. Might be able to be used on WOLF though they're a bit heavy. I'll look into it some more when I have time.

This is the mainfoil and rudder foil-both would have to be modified a bit. They were designed by me and built by John Ilett:

 

WOLF---daughter of fire arrow / Concept Model

Got the two stage ama's cut and reassembled today with the ama hull lower than it was originally. This allows the crossarm dihedral to remain as it was to start with without having the ama hulls too high. Tricky and tough job but all part of the design process for the final fullsize boat.
More soon......

 

WOLF---daughter of fire arrow

Updated 3/22/17 specs and notes: (see previous page)
NOTE: I'm sure various changes will continue until(and after) the boat is launched-that's what development is all about.

WOLF Specifications

LOA 15.458' (4.7m)
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Beam max-18.75' (5.72m)changed 3/22/17
-beam folded-8' (2.4m)
-main hull beam on deck: 2.625'(.8m)
-main hull beam at wl: 2.125'(.65m)
-main hull L/B at wl:7.27/1 (planing)
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Two Stage Ama-11.5' (3.5m) changed 3/22/17
-ama hull-7.7' (2.35m)
-ama hull beam .58' (.18m)
-ama hull L/B=13.3/1 (planing)
- curved piece-5.9' (1.8m) changed 3/22/17
- overlap- 2' (.61m)
- two stage ama canted bottom out 12 degrees.
- two stage ama buoyancy(not including crossarms)=252lb(61%)
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Weight:
-boat-210lb (95.45kg)changed 3/22/17
-crew-215lb (97.7kg)
-sailing/flying weight: 425lb. (193.18kg.)changed 3/22/17
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Sail Area:
-main + jib= 165sq.ft(15.34sq.m)changed 3/22/1
- spin/screecher about 150 sq.ft(13.9sq.m)
-pounds per sq.ft./SA:
--upwind=2.58 changed 3/22/17
--downwind=1.35 changed 3/22/17
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Designed flight angle of heel: 5.5 degrees to 15 degrees. Standard 10 degrees.
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Main hull flight altitude at centerline: .5'(.15m)---2'(.61m),Standard 1.19'(.36m)
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Righting moment:
-crew 215 @11'= 2365ft.lb.(3206.5 N/m)*
-boat 200 @ 7.5'=1500ft.lb.(2033.7 N/m)
TOTAL RM= 3865ft.lb (5240.2 N/m)
Downforce from main foil(if used) approx. 1500ft.lb.(2033.7 N/m)
* N/m conversion done from online converter
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Foils:
-uptip foil in each ama, adjustable AOI and up/down(mostly retractable). tentative AOI-3-5 degrees over twisted foil.
-mainfoil wand altitude control, adjustable AOI(nominal 2.5 degrees),up/down(mostly retractable).
-rudder T-foil, adjustable AOI(nominal zero degrees),retractable.
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Planing surface on lee ama hull is designed to be flat when main hull is just clear of the water(6") and that will occur at an angle of heel of 12 degrees.

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Are you modelling these changes in a design software?

 

WOLF---daughter of fire arrow

No, I don't use any design software. By hand and with a calculator-the old fashioned way. The model is key to doing the design except I think I can see more than I would with a render.
It's fun!

 

It's clear that you love modelling.
3D work, apart from shortening time between iterations, can be rewarding on its own. And it's its own form of modelling. Delftship is an easy entry point. Dip your toes if you haven't ...

 

Computer Aided Sailboat Design

If I can make the time I'd like to get into it at some point.

 

WOLF---daughter of fire arrow / Concept Model

Here are some shots of the modified boat and the first version:

Unmodified boat:



modified boat:

 

WOLF---daughter of fire arrow / Concept Model

Top View with seats:

 

WOLF---daughter of fire arrow / Folding,again

As mentioned before, the boat will fold into an 8' wide package on the trailer. Should take somewhere between 2 and 4 minutes to fold or unfold. See the illustration of the folding system below. The ama foils stay in place but retracted. Seats don't move.
The folding system is light weight and allows a rigid, oversquare platform assembly-the widest trimaran of its size(currently).
Eric also did the engineering on the tubes shown in the illustration so that there would be no requirement for waterstays or other reinforcement.