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

WOLF daughter of fire arrow
Specifications
Latest Update 4/7/19
==================
A) WOLF specs(tentative) :
LOA 15' 8"
Max Beam 16'
CL ama hull to CL ama hull-14'
Target weight 175-190lb
SA-(mast length 24' all carbon wing mast)
--upwind: 185 sq.ft
--downwind: 300 sq.ft
--max pressure before depowering/reefing:
-----UptiP Foils= 1.15 lb/sq.ft
-----Welbourn Foils= 1.8 lb/sq.ft
* NOTE-see "F)" below for max pressure comparison with an F18.
------------------------------------------------
B) Advantages:
1-Singlehander- Excellent upwind and downwind performance with 220lb crew. Minimum crew weight 120lb. Two people for daysailing-max about 340lb.
--
2- Will foil in 5 knots of wind with 220lb crew .
--
3- Carbon rotating wing mast, carbon cross arms and carbon foils.
--
4- Retractable foils(from cockpit). Mainfoil retracts flush with bottom and tips are designed to not dig into sand. Rudder foil retracts above bottom. Ama foils retract above waterline when boat is level.
--
5- Extremely comfortable sliding seat on each side. Allows crew to move 1.75' outboard very quickly.
--
6- Uses the Fire Arrow Foil System(like Fire Arrow, Gitana 17, Banque Pop, Macif , Macif jr(24'Diam tri) and Maserati)-- the same as the original system first used on the Test Model- except the larger boats use two rudder t-foils on each tack. WOLF has two UptiP ama foils-one used at a time-and one wand controlled mainfoil for very early takeoff and capable of substantial downforce- all working with a single rudder T-foil. Downforce can be virtually instantaneous adding RM in response to gusts. UptiP foils stay down-no adjustment when tacking or gybing.
(see #16 below)
--
7- Foiling throughout the wind range -including very light air-the essence of 3D SAILING!
--
8- Assy Spin/Screecher retracted under the front deck.
--
9- Boat folds from max beam to trailerable width in about 4 minutes. No waterstays.
--
10- Mid (wish)boom mainsheet so sheet is always in forward hand and extension tiller always in aft hand.
--
11- Quickly self-draining cockpit-large scuppers with backflow flap.
--
12- Planing ama hulls designed for incidental contact with water at speed and for inadvertent contact at slow speed.
Adjustable angle of incidence of planing surface of each ama simultaneously. Angle of incidence of ama foil has to be changed when this is done. Planing surface starts at +4 degrees.
Uses Two-Stage Amas-see attachments below. They consist of a planing ama hull(Stage One) coupled to a "curved piece"(Stage Two) that provides extra buoyancy in the event of a knockdown. Curved piece facilitates high dihedral crossarms which keep the crossarms clear of the water.
--
13- Planing main hull.
--
14- Aerodynamic surfaces added to forward and aft crossarms. Adjustable flaps added on rear cross each side. Jib foot and forward part of main foot to be sealed to deck.
--
15- Automatic Foiling: no foil adjustments required after shoving off the beach and lowering the foils.
--
16- Adjustable crossarm dihedral for prototype to facilitate testing.


-------
==================
C) ---Memorable quote from JG Baker, Designer and Builder of the Monitor foiler in the 1950's:
" The main need is to lower the wind velocities required for flying in order to increase the opportunities for high speed travel"

D) ---VPLP on the daggerboard main foil:
" On these big boats, when you ease a sail, it is a pain because it takes so long to grind it back in. But here you press a button and the angles of incidence change. And with the foil on the daggerboard you can use it to alter the flight according to the wind*. If it builds, rather than easing the sheet you increase the righting moment by increasing the angle and conversely, as it eases you can reduce it and let it fly more."
* done 100% automatically on Fire Arrow/ WOLF with wand controlled main foil.

================
E) --- Fire Arrow Foil System-first of its kind on any trimaran. Elements developed first by Fire Arrow include:
1) the first trimaran in history to use UptiP ama foils,
---
2) the first trimaran in history to use a single wand controlled main foil capable of downforce,
---
3) the first trimaran in history to use Two Stage Amas.(see below for Two-Stage Ama pictures)*

=======================================================
F) Max pressure for F18 and WOLF before depowering or reefing :
1)-The max pressure for an F18 based on 229 sq.ft. upwind SA, CE at 16.9', 2-180lb crew on trapezes and 5320 ft.lb. RM is 1.39 lb/sq.ft..
---
2) --UptiP Foils-Max pressure for WOLF with 185 sq.ft. upwind SA, CE at 14', one 220lb crew sitting in a comfortable sliding seat, and 2992 ft.lb RM* is 1.15 lb/sq.ft..
---
3)--Welbourn Foils- Max pressure for WOLF with 185 sq.ft. upwind SA, CE at 14', one 220lb crew sitting in a comfortable sliding seat, and 4654 ft.lb RM* is 1.8 lb/sq.ft..
Note: Welbourn foils provide 1.56 times the RM possible with UptiP foils*.
*not including downforce automatically generated by the wand controlled main foil.
===========================================================
G) *The Two Stage Ama Design offers a lot both Statically and Dynamically:
1-Statically- the boat is sitting still and hit by a hand of God gust. It is theoretically possible that the boat could be knocked over with the mast horizontal but the two stage ama offers reserve buoyancy after the the ama hull itself is immersed by the immersion of Stage Two("curved piece") and yet it is not enough to fly the main hull. It is enough, however, to right the boat.
2-Dynamically-The ama hull has two levels of dynamic vertical force:
a. first and foremost the ama lifting foil that works from very low speed on up,
b. Second, and a sort of back up at speed, is the planing hull design of the ama. To start with on Fire Arrow/WOLF, the planing surface only comes into contact with the surface at very low speed with the ama starting to fly before the main hull does. And when the boat is flying the ama performs as reserve lift during incidental surface contact at speed.
*Also see page 191, post 2865 for more on the Two Stage Ama theory.


======================================================
UptiP Ama Altitude Control-pictures A & B----
Note that the ama is flying before main hull-note ama flight altitude:


Now that the main hull is flying and speed and load are significantly greater than in "A" above, note that ama flight altitude is the same! And that's due to the ama UptiP foil design(no moving parts) :

=======================

 

Fire Arrow Self-Righting--theory

==================================

 

Experimental Foils: only the partial span main foil and the ama foil have been fully tested but most have, at least, the potential of beneficial results. Some also have a degree of potentially high drag that needs to be evaluated carefully:











Welbourn 3 degree twisted(wash in-where AOI of foil increases toward the tip-the opposite of wash-out) surface piercing foils with adjustable cant on the D2 platform-the wash-in portion of the foil will be above the surface as speed increases:


Theoretical incarnation of a T-foil with intrinsic altitude control-concept sketch-not a final design. The idea is to try to develop a T-foil with intrinsic altitude control similar to an uptip foil but with the center of lift much further outboard as compared with an uptip foil:

---
Partial span flap wand controlled mainfoil for Fire Arrow and F3. Designed with a very thin T/C ratio of around 6-7%. Used on F3 RC production sailing foiler 19 years ago and worked well on Fire Arrow in 2014. Benefits probably limited to model foils:

==================================
UptiP foil with intrinsic 15 degree iFlap-partially tested- appears to work well. The idea is for the lift developed by this foil to match the wand controlled lift of the mainfoil* on Fire Arrow from slow to high speed:
* the AOI of this foil changes as it would with wash-in(not wash-out)-that is ,the AOI increases toward the tip with the expectation that the tip will breach the surface at higher speed. Drag throughout the speed range needs to be analyzed.


Same as above:

 

I just heard that Tiger won his 5th Masters !! Congratulations on a tremendous, inspirational comeback!! Absolutely fantastic.
What a tremendous inspiration he is to me........

 

UptiP Foils: How they work by Tom Speer and Magnus Clarke
----------------
The foils I'm using on the Fire Arrow amas are based on the Team New Zealand UptiP foils which are a real foil design breakthrough because they have "intrinsic" altitude control when used as a single main foil on a cat(or as an ama foil on a tri. Note-all of the most recently launched Ultim trimarans use UptiP ama foils)
This is a succinct description of those foils by Magnus Clarke. A more complex description by Tom Speer can be found below:

Magnus Clarke:
"The Emirates Team New Zealand system, which is really the basis for C-Class foiling, relies upon the use of leeway to moderate the effect of the lifting foil and to help make the boat heave stable. As the boat sails down the track and begins to fly it speeds up a great deal due to reduced drag. This extra speed allows for a great deal more lift to be produced by the foils and so the boat rides higher, as the mass is constant. As the boat rides higher there is less foil in the water. If the strut is principally responsible for limiting leeway there is now less of it to do the work of keeping the boat moving forwards. The boat automatically corrects for this by yawing, at which point the strut will use a higher angle of attack caused by the leeway to create a force equivalent to the wing's side force.
The leeway, however, has an effect on the effective angle of attack that the foil wing experiences. As the boat crabs sideways the wing- or relatively horizontal- portion of the foil sees a lower effective angle of attack and as such the lift produced is moderated or reduced until the boat itself reaches dynamic equilibrium. This is also aided by the inboard tip starting to breach out of the water-this reduces available area to create lift for the boat and also leads toward dynamic stability in heave."
====
Tom Speer:
"The curved part of the vertical foil produces essentially the same lift as it rises. This is necessary to counter the side force from the sail rig, which does not change as the height changes.

Because the horizontal lift is constant but the vertical area is reduced as the boat rises, the leeway angle increases. It is the coupling of leeway with heave that is exploited by the L foil to provide vertical static stability.

The dihedral angle of the horizontal wing is set so that the angle of attack of the wing is reduced as the leeway angle increases. This satisfies the static stability condition that the vertical lift decrease as the heave increases.

Because the same horizontal lift is produced over a reduced vertical span, the sideways wash in the wake is also greater and the trailing vortices are more intense. This causes a coupling with the horizontal wing that increases the vertical lift, because the horizontal wing acts as a winglet for the vertical part of the foil (and vice versa). The dihedral angle required for vertical stability is greater than what one might expect by looking at the wing alone because it must overcome this wake-coupled influence. The result is there is a range of dihedral angles that provide positive vertical stability and a range of dihedral angles that are destabilizing in heave because of the coupling with the shed vorticity of the vertical part of the foil.

Although there are times when the foil tip has broached the surface, this is not the normal mechanism for providing heave stability in L foils. The best performance is obtained with the hull just above the wavetops and the wing submerged well below the surface. The leeway-modulated heave stability is still effective in this condition, and the induced drag is minimized.

Canting the foil inboard has the effect of increasing the dihedral angle of the wing, which enhances the heave stability. The vertical lift is spread over a greater span because the curved part of the foil is oriented to provide more vertical component of the force. This reduces the induced drag due to the vertical force. However, the induced drag of the horizontal force would be increased, so cant is typically used off the wind when the side force from the rig is less and the side force produced by the foils is correspondingly less. The foils still have to support the weight of the boat, so the vertical force is not lessened, but the relative proportions of vertical and horizontal force are changed, making the canted foil better suited to the operating condition. Cant allows the leeway-modulated heave stability to be increased an an acceptable penalty in the induced drag because of the lower side force and the higher speeds, which also reduce induced drag.

Upwind, the foils are canted to their vertical position to minimize the induced drag from the high side force and reduced speeds. The reduction in horizontal wing dihedral angle with vertical cant impacts the leeway-modulated heave stability, which is why it is much more difficult to achieve stable flight upwind than downwind. The crew had to be more active in trimming the wing and foil to deal with the reduction in natural heave stability, which was very hard on the grinders when flying upwind.

Whether canted or upright, the mechanism for providing natural heave stability was still the coupling between heave and leeway, which led to a reduction in vertical lift because of the designed-in coupling between leeway and vertical lift by virtue of the wing dihedral. Reduction in horizontal/vertical-lifting area due to the foil tip broaching the surface was not part of this primary source of heave stability. Allowing the tip to broach the surface had big penalties in terms of induced drag and increased leeway due to insufficient vertical span."

UptiP Ama Foil on Fire Arrow Test Model:


UptiP Ama Altitude Control-pictures A & B----
A-Note that the ama is flying before main hull-note ama flight altitude:


Now that the main hull is flying and speed and load are significantly greater than in "A" above, note that ama flight altitude is the same! And that's due to the ama UptiP foil design(no moving parts) :


Ama UptiP Foil Partially Unloaded :

 

Mainfoil Control on Fire Arrow and WOLF:
On WOLF and Fire Arrow the main foil is controlled by a surface sensor otherwise known as a wand. The wand is directly connected to a flap on the foil and as shown in the short video below the boat can change flight altitude as the flap is moved. One of the most important elements of the wand is that it can cause the foil to generate downforce instead of vertical lift and in the application on WOLF and the Fire Arrow this results in increased righting moment/power to carry sail.
The foil is automatically controlled maintaining a preset angle of heel for the whole boat. The mainfoils on the big tri's are controlled by manual adjustment of an electro/hydraulic system. Automatic control is illegal, for the time being, on the big boats:



The Fire Arrow Foil System is comprised of the automatic wand controlled main foil ,trailing rudder T foil on the main hull and on each ama there is an uptip foil which has automatic altitude control with only the leeward foil being used at any one time.
This foil combination along with the Two Stage Ama is unique to the Fire Arrow/Wolf and allows extremely good control of pitch and roll as well as the complete adjustability of the boats pitch attitude, angle of heel, righting moment and lee foil ride angle. One of the major characteristics of the Fire Arrow Foil System used on the Fire Arrow Test Model and on the new ,fullsize, WOLF is that shortly after lift off the mainfoil is unloaded as the boat reaches its design flight altitude which reduces drag.
The Fire Arrow Foil System is a unique, automatic, foil system making flying easy and safe and allowing light air takeoff with increased stability in strong winds.

 

Giroptic 360 degree camera: This thing really attracted me when I first found it after the GoPro disaster. I decided to wait for financial reasons. Unfortunately, they have gone out of business-a sad story..........

 

WOLFMAN-- This guy is 5' 4" tall at the same scale as the rest of the boat. He helps to visualize the size of the boat and various components.

 

WOLF song? My favorite music these days is First Aid Kit--those two ladies are terrific. Just found a song they do called: WOLF-
From First Aid Kit “Lions Roar” album 2012:

Johan Söderberg, who is not related to the two First Aid Kit sisters, directed the song's music video. It was filmed, "in the deep dark forest of Järvsö, Hälsingland." The Söderberg sisters explained: "It's about our destruction of the planet, but it's also about finding the animal within you. Because we know that underneath that polished, civilized exterior there is definitely a wild creature longing to howl or roar."
Right!! HEY YA HEY YA


video described above:

 

WOLF by Joe Walsh:

 

SAIL LOADING- an indicator of hydrofoil performance. Divide total sailing weight in pounds by sail area in sq.ft.( reference: Moth= 2.86lb.per sq.ft. sail loading w 180lb crew).
WOLF- upwind SA 185, downwind SA 300. Weights using highest estimated boat weight* + 220lb for one person and +340lb for two people(MAX).
* 190lb
------
upwind-one person=2.21 lb./sq.ft. sail loading @ 410lb total flying weight
two people=2.86 lb/sq.ft.sail loading @ 530lb total flying weight
--
downwind-one person=1.37 lb/sq.ft. sail loading @ 410lb total flying weight
two people=1.77 lb/sq.ft. sail loading @ 530lb total flying weight

 

Good article here on Dynamic Lift(and downforce) - multies primarily but monos too- with Vincent Prevost(VPLP). Can Dynamic Lift using foils help an ocean going cat to beat a tri?
Dynamic lift(downforce): Cat vs Tri- https://www.boatdesign.net/threads/dynamic-lift-downforce-cat-vs-tri.62224/

 

Jumping for the fun of it or because it was a test or(?) :
The jumps of the two models, one with a rudder T-foil and one without, were caused by the skipper putting the helm hard over too quickly.





Maserati testing lift of main foil:

 

Fire Arrow Foil System-rough water capability:
In a couple of posts including below I mention that I think the Fire Arrow Foil System will be particularly good in rough water. In November 2018, Gitana 17 and Banque Populaire both using a version of this foil system sailed the fastest they ever had in the roughest water they had ever foiled in. Unfortunately, both boats broke in the extremely rough conditions. But the foil system didn't break-in fact it worked better than even the designers had anticipated and before the boats broke the foil system showed its capability for flying in very rough conditions.
On the second day of testing the Fire Arrow was sailed in conditions where it was seriously overpowered. That was bad judgement on my part because it could have ruined a $300 winch. But boy was it fun-and the boat handled the conditions extremely well and I was convinced then that this foil system would do very well in tough conditions-exactly what Gitana 17 and Banque Pop proved in the Route du Rhum 2018!

Note-updating post below started 5-13-19 for the next few days: