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

WOLF---daughter of fire arrow / Concept Model

Dihedral and more: (full size specs, previous page, post 2482)

 

WOLF---daughter of fire arrow / Specs

Updated 2/1/17 specs and notes:

LOA 15.458' (4.7m)
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Beam max-18.3' (5.58m)
-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-11.3' (3.5m)
-ama hull-7.7' (2.35m)
-ama hull beam .58' (.18m)
-ama hull L/B=13.3/1 (planing)
- curved piece-5.7' (1.74m)
- 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-200lb (91kg)
-crew-215lb (97.7kg)
-sailing/flying weight: 415lb. (188.7kg.)
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Sail Area:
-main + jib= 160sq.ft(14.9sq.m)
- spin/screecher about 150 sq.ft(13.9sq.m)
-pounds per sq.ft./SA:
--upwind=2.59
--downwind=1.34
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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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WOLF---daughter of fire arrow

Well, the main hull and two-stage amas have been filled and rough sanded. A few more days and the concept model will be assembled. This along with the Fire Arrow Test Model will be a couple of the "tools" I'll use to get the WOLF project off the ground.








click:

 

WOLF---daughter of fire arrow

I've filled and sanded the boat and will Duratec it then wet sand. At that point, the crossarms will be assembled to the two stage ama's and then to the main hull. Next will be installing the seats and possibly some aero fairings.
I still have to finish the wing mast and make and install the foils and sails.
There is the rudder T-foil, Daggerboard T-foil and an UptiP foil for each ama hull.

 

Maserati -Season Two--and Fire Arrow/WOLF daughter of Fire Arrow

Maserati, the converted MOD 70 has a foil system very similar to the Fire Arrow Foil System in some important ways. So similar that her foil system testing has shown that the basic Fire Arrow System will work on a large trimaran ocean racer and that fact has pushed me to go forward with WOLF!
But there are some important differences that may be due just to the difference in size and I want to talk to Guillaume Verdier about that at the earliest possible time.
--
The major differences are the two-stage amas, and the active, wand controlled main foil on Fire Arrow, and the large rig on Fire Arrow/WOLF. And that Fire Arrow/WOLF are designed to fly in very light air(5mph Fire Arrow Test Model, 5 knots WOLF whereas Maserati requires 15 knots of wind to fly. I'm thinking that's because Maserati is a "standard" MOD 70 that has been converted to a foiler where my boats are designed from scratch as foilers.
The Fire Arrow and WOLF use oversquare platforms that allow tremendous RM in stronger wind while the active, automatic wand controlled main foil allows the oversquare platform's main hull to fly before it would normally just due to wind pressure. This allows a drastic reduction in drag in light air . The rig for the Fire Arrow/WOLF is much larger than a rig for a "normal" trimaran of the size of the two boats.
And that's where MOD 70 falls short since it has a conventional platform and rig not specifically designed for its foil system.

Check this out:

http://www.boatdesign.net/forums/multihulls/maserati-70-ocean-racing-foiler-57254.html

 

Hi Doug, I think you need to rethink your logic. The smaller the boat the more sail area you can put up, so the SA/weight ratios are huge on model boats compared to sea going boats. The design of a foiler is a compromise as you know. Its very easy to design a boat that can fly in light wind. But the penalty is that the foils will be too big for going fast. So you need to decide what is the fastest target speed you want to sail at design here then come back to the takeoff speed and decide if its too slow/fast then redo until you get the best range closest to the speed targets you want. Something like the Mod70 will do 15 knots in nearly nothing so its not a bad place to start. There are lots of standard boats and dingies bolting on foils and flying very well and they certainly didn't even think they would foil one day eg the laser. Peter

 

Fire Arrow Test Model Testing and Development / WOLF

Thanks, Peter. In my experience when you scale a big boat down to a model you lose a lot of RM so can't carry as much sail as the big boat in anything but very light air. When you scale up a model you gain a lot of RM so the model sail area can generally be increased on the full size boat. But that is a bit different on the Fire Arrow since its active wand controlled main foil can develop a great deal of RM through downforce so it can carry a lot of sail. But the full size version will be able to carry even more. I designed the 5' LOA Fire Arrow to be the largest model I could afford to mitigate these changes between the model and the original 19.5'( by 22' beam) full size version. The WOLF is only 15.5'LOA and 18' wide.
Another element to consider is that when using a wand controlled foil with a flap the foil is automatically configured for light air takeoff due to the fact that the wand moves the flap down 30 degrees so you can have a foil that works well in a wide wind range. Maserati has the facility to change the AOI of the mainfoil but only manually(hydraulically) and it will develop downforce as well.
In my last post, I said that I wanted to talk to Guillaume Verdier about the factors involved in using the Fire Arrow platform concept on a larger tri. There is no question that the MOD 70 is not designed for the foil system that Maserati is using(which is basically the same as the Fire Arrow Foil System now)-I'm curious if it could be designed with a greater beam and /or carry more sail to make up for the deficit with Phaedo in light air. If the boat was designed for it I'm fairly sure it could carry more SA in light air-I just don't believe that a non-foiling trimaran should have the advantage Phaedo clearly does. It would probably be prohibitively costly to modify the MOD 70 any further but I'd bet that a large foiler tri could be designed and engineered to out perform any other non-foiling trimaran it's own length in any condition. I could be wrong but that's what I want to talk to Guillaume about. He's a great guy and very generous with his time-we've e-mailed back and forth since Maserati's last campaign.
Thanks for your input!

 

WOLF---daughter of fire arrow / concept model

I had to do the Duratec by pouring (very carefully) since I can't spray the stuff.
I catalyzed it exactly as per their directions at 2%. It was a good pour on the main hull --until I tilted it to one side and the Duratec ran down the side making horrible streaks-instead of a nice even streakless pour. The amas turned out ok but all three parts had pin holes that I've never seen before with this stuff. One whole day of sanding Saturday and then filling on Sunday. Should come out ok with final wet sanding tomorrow. The whole idea of pouring is to reduce sanding time-but when you screw it up no time is saved. I've done this right many times over many years but this one was not my best.
Should be able to assemble the crossarms to the amas, then the ama assembly to the boat later this week.

 

WOLF---daughter of fire arrow /concept model

Here are some shots of the boat ready to assemble and almost ready for paint.
Just have to detail the spinnaker trough. The cockpit will be "upholstered":

 

WOLF---daughter of fire arrow

Couple more shots-should be assembled soon:

 

WOLF---daughter of fire arrow / Phaedo Canting Mast

This picture's got me thinking: Maserati, when both sides of her foil system are working will sail mostly level. But the Fire Arrow and WOLF sail at about a 10 degree angle. And that would make a canting mast a speed producer on WOLF-but too much trouble for the model.
I hadn't realized that Phaedo had a canting mast and it obviously works for them-a small edge especially when Maserati's foil system is crippled.

 

WOLF---daughter of fire arrow

WOLF will be my personal boat and will be used a lot to explore various little islands which means being able to pull it a bit up on a beach. One of the problems with that is the daggerboard lifting foil which normally would hit bottom. I'm thinking I may make a recess in the main hull that would allow the foil to pull up clear of the sand. The drag with the board down may be able to be dealt with though I'm not sure how yet. It will only be a problem(if at all) in non foiling conditions which means in wind under 5 knots.
Anyone with any thoughts on how to do this?

PS- the amas and ama foils are clear as soon as they are retracted as is the rudder.....

 

A recess in the hull would raise your take-off wind speed a bit by adding drag, so if the main reason you want it is for dragging the boat up a beach, I'd look instead at putting a pair of wheels down just behind the foil so that you can pull the boat along backwards by the stern and have a cable connecting the wheels hit any rocks before the foil.

The greater problem is not being able to get all that lifting surface out of the water in light winds, and a recess won't fix that. The only potentially-viable solution I can think of would be to put all the structure of the bow on one side and have a removable section on the other side that allows you to extract the foil sideways. That would add a little weight, but your bow is so wide that it should still be easy to provide enough structural support for the mast and forestay that way (with the spinnaker tunnel running through that side too). Most of the removable section could be narrower than the foil as you would be able to rotate the foil by 90 degrees before removing it, so the removable section could potentially be just an inch wide for most of its length with a wider bit next to the foil to give you room to rotate it, and that might still make it possible for the removable part to play a structural role once it's locked in place. It's obviously not an ideal fix, but I suspect the gains may be big enough to justify it because the inability to remove the foil in shallow water where it may be rocky is such a big issue with the design.

 

WOLF---daughter of fire arrow

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Thanks for the comments. I'd hate to have to take a dolly with me but it's worth considering.
The boat will take off in a 5 knot wind so for all practical purposes she'll fly any time I go out. The drag caused by the recess won't matter very much but I need to study it and decide if it will work. There may be a way to use foam in such a way that when the mainfoil is deployed the recess fills in automatically?

 

I'd design two pairs of holes into the underside of the hull that a couple of simple structures holding wheels can be plugged straight into, with the plugs that normally fill them being pulled up first from above to leave a few inches of socket open. Then I'd design a compartment in the the bow specifically to hold the wheels so that it's easy to carry them with you without any windage issues or ever having to fiddle around tying them on. By making this a standard part of the design, you'd massively enhance the practicality of the boat for a trivial increase in weight and infinitesimal added drag. Wherever you land, you're going to want to fit the wheels, so I reckon they're essential equipment. This is an issue with all dinghies, frequently limiting what people are prepared to do with them - trolleys and dollies are a pain, so you want to simplify things right down to the minimum, and if that means having a few extra holes in the hull to make it work, it's a small price to pay.