Fire Arrow Foiling/ 3D Sailing Trimaran Test Model - Page 15 - RC Groups
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Feb 04, 2018, 07:31 PM
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Years ago we had talked about electronic stabilization and the tech just wasn't really there. Now a 3 axis controller like a Naze32 or CC3D is less than $20. One with a mag compass would be cool, but one with logging would be really interesting.

Almost wondering if one should log a normal tri to see what the forces were like, then work backwards to see how much stabilization is needed.
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Feb 05, 2018, 07:26 AM
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Fire Arrow

Lots of good stuff available but one thing may still be missing: an electronic means of altitude control or at least an electronic means to measure small amounts of altitude over water accurately that could be tied into a servo. Thats the problem with the Fire Arrow -the wand is still the best solution for the mainfoil altitude control as best I can tell.
On Fire Arrow S the ama foils don't need any altitude input -they will be simply shifted between takeoff AOI and "cruise". But the mainfoil needs altitude input to work electronically.
Even the SuperFoiler doesn't require altitude input-the foils are controlled manually and moved electronically.

Last edited by DLord; Feb 08, 2018 at 02:23 PM.
Feb 13, 2018, 10:15 AM
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Fire Arrow Tech

Fire Arrow Foiling System Testing and Development

Updated Fire Arrow System Advantages:
Note-the basic Fire Arrow Foil System is now working on Maserati, Gitana 17 and Banque Populaire with versions designed by Guillaume Verdier and VPLP.

One of the great advantages of using a properly designed UptiP foil on a foiling trimaran ama is SIMPLICITY: on the Fire Arrow the ama foil has NEVER needed to have the angle of incidence adjusted while sailing as is common on many UptiP foil applications. And if the foil is properly designed for it's application ,it's efficiency will be apparent. As shown in the pictures below the lee ama flies before the main hull, but as soon as the boat speeds up and the main hull flies the lee ama altitude remains the same. That illustrates that the lee UptiP foil is working PERFECTLY in two different load and speed cases.See pix "A" and "B" below.
The Fire Arrow uses a wand controlled main foil which controls the altitude of the main hull and the angle of heel of the whole boat. Further, and this is very important: the wand controlled main foil works with the single rudder T-foil in a bi-foiler arrangement and the two together control the ride angle of the lee ama UptiP foil. That prevents pitch excursions caused solely by the lee ama foil.
The way the mainfoil works is that as soon as the main hull flies the mainfoil begins to unload with the lee ama foil gradually taking the majority of load. That allows the mainfoil to work with the rudder T -foil to control the pitch of the boat with far more pitch authority than on a conventional tri. And, using a wand controlled(or similar) foil on the daggerboard allows the main hull to fly MUCH SOONER than it would if it had to wait for wind pressure to do it.
The mainfoil can also develop substantial downforce* increasing the righting moment in response to gusts. All this is done 100% automatically making for a simple, robust system that requires ZERO crew attention!
* with downforce, the main foil works similarly to a Moth foil with Veal Heel, generating a component of lift to windward.See illustration below.
The vertical portion of the ama foil is at +3 degrees AOI. The vertical portion of the daggerboard is at zero degrees. So the UptiP ama foil is developing lift to windward to allow leeway coupling and develop lateral resistance for the boat particularly upwind.
In stronger conditions, when the main foil develops down force( upwind), the leeway components are greater than the vertical portion of the UptiP foil can effectively handle, there is a small extra component of lift to windward(due to downforce)-while the vertical portion of the ama foil is still working at 100%. The daggerboard is designed to be unloaded by the lee ama foil to reduce drag and facilitate leeway coupling.
However, it should be pointed out that the ama foil will still provide substantial vertical lift with little to no leeway coupling-like can occur off the wind. Lift substantially(and automatically) increases upwind because of leeway coupling.
Testing clearly shows the progression of the boat to full foiling from the problems encountered at the beginning-the last video is 100% proof that the foil system worked perfectly!
See the 9/16 video of Maserati to see the basic Fire Arrow system in use on a 70' tri. Also see the recent Gitana 17 video below showing the first full size trimaran designed from scratch by Guillaume Verdier to use his version of the basic Fire Arrow Foil System.

We reached a major milestone with the boat foiling in a 5 mph wind while using two different altitude control systems simultaneously. July 24th, 2014 was a major accomplishment for the boat after a great deal of design and development over 4 years. Each attribute below was proven during the month and a half testing in 2014 culminating in the 7/24/14 testing where the foil system worked exceptionally well.
Proven attributes of the Fire Arrow Foil System:

1) allows an oversquare trimaran to foil in very light air and be stable in heavier air,
2) allows full foiling upwind and downwind completely automatically without any adjustments by the crew,
3) allows for retractable foils controlled from the cockpit,
4) allows the lee UptiP ama foil daggerboard portion, with an AOI of +3 degrees, to unload the daggerboard(AOI zero degrees) for reduced drag and enhanced leeway coupling. The ama foils do not require constant rake adjustment-basically set it and forget it.
5) the foil system has considerably greater pitch authority than any conventional trimaran,
6) allows automatic control of the angle of heel of the whole boat,
7) allows automatic control of the ride angle of the lee ama UptiP foil.
8) allows mainfoil to automatically unload as the mainhull flies ,dramatically reducing drag.
9) allows automatic gust response with instantaneous increases in righting moment (automatically) as required through mainfoil downforce.
10) allows a "Two Stage" ama that provides back up buoyancy if needed but allows the part of the ama that would normally make incidental contact with the water to be as small as practical.
11) allows the use of UptiP ama foils without the requirement to retract/deploy a foil with each tack or gybe-a requirement on every other multihull using uptip foils. Foils can stay in their deployed position without retracting except for shallow water/beaching.
12) allows use of two different types of altitude control simultaneously.

Maserati video:
Maserati Multi70 ocean-bound and in full flight (1 min 15 sec)

Gitana 17 video:
Le Maxi-Trimaran Gitana 17 vole - Le Havre Bretagne Tele (3 min 31 sec)

Downforce + windward component:


Gitana 17
Last edited by DLord; Mar 25, 2018 at 07:16 PM.
Feb 27, 2018, 07:05 PM
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Fire Arrow and/or Fire Arrow S

I'm definitely considering a new version of Fire Arrow designed for speed as a model and not designed to scale or to any rule. One of the things to test on either model are Welbourn outward facing foils that can increase righting moment substantially.
A fullsize "sport" version could use this foil system to have a narrower platform for ease of stowage/transportation.
An RC or fullsize racing version with a center lifting foil like the Fire Arrow scale model but wider overall beam could use the foils strictly to add RM in light or heavy air.

A previous post from 2016 on the subject with a rough illustration of the concept:

Originally Posted by DLord
With my work on Dominion 2 using Hugh Welbourns foils it occurred to me that those foils could work well on a trimaran using the Fire Arrow System. They could allow a narrower platform if the center of lift of the new foils was in the same place as the original UptiP foils OR much more righting moment due to the increased distance of the center of lift of the foils from the athwartship center of gravity of the boat:

Last edited by DLord; Feb 27, 2018 at 07:13 PM.
Mar 25, 2018, 07:15 PM
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Fire Arrow TAKEOFF!

Found the top picture a short while ago-I don't think its ever been used. In combination with the bottom picture it perfectly illustrates takeoff in very light air:

Apr 27, 2018, 09:21 PM
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Fire Arrow Advantages

This is a document I put together for a friend to help her understand the boat and its tech a bit better.
May 06, 2018, 04:35 PM
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Fire Arrow Foil System: Automatic Mainfoil Control

Vincent Prevost's comment* in an e-mail to me is interesting and surely an important consideration in design of a daggerboard with a lifting foil for a trimaran of any size.
*"at the heel angle where the board is out the water, you brutally loose 20% of your righting moment."
Early in the design of Fire Arrow that was very much on my mind hence the relatively deep daggerboard. On Fire Arrow, the boat is designed to sail at a 10 degree angle of heel in order to keep the windward ama foil clear of the water without the crew having to raise or lower it after a tack or gybe.
In addition, the boat was designed from scratch to be able to effectively utilize mainfoil downforce. The purpose of the wand controlled mainfoil is to lift the mainhull early -before it would lift due to wind pressure on the rig. Since the mainfoil is relied upon to do that, I was able to increase beam so that the platform is oversquare. On a "normal" tri an oversquare beam can be problematic because the RM is then so great that it takes a relatively strong wind to fly the main hull. But with the wand controlled mainfoil the main hull lifts in very light air-about 5mph.
The oversquare beam helps the mainfoil downforce to work more efficiently due to the distance between the mainfoil and ama foil. And the downforce from the mainfoil can substantially increase righting moment. The automatic wand control of the mainfoil flap can allow almost instantaneous gust response.
The fact that the functioning of the mainfoil is essential to the performance of the Fire Arrow from the lightest air to the strongest wind means that it is mandatory that the mainfoil is low enough not to be at risk of "popping out" at any time. The extra depth can add a bit of drag but the increase in power to carry sail due to the oversquare platform(made practical by the wand controlled mainfoil) is a huge performance gain for the boat and completely offsets any additional drag due to the deep daggerboard-in light or heavy air.
If the big boats could use some sort of electronic system that would fly the mainfoil like the wand does on Fire Arrow, it might be possible to increase beam/daggerboard depth to take advantage of the characteristics of an automatically controlled main foil. At this point in time, automatic electronic foil control is illegal in the ULTIM class and a wand probably impractical. The biggest boat,so far, to use wands to develop lift and righting moment was Dr. Bradfields 40' SKAT.
I believe a Formula 40 tri could use a wand controlled mainfoil almost identical to the Fire Arrow System.

Banque Pop's main foil "popping out"-note daggerboard may have been intentionally up but nevertheless it shows how the foil can come "loose" intentionally or not-see one minute eight seconds in:

Last edited by DLord; May 06, 2018 at 04:43 PM.
May 07, 2018, 08:26 PM
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Gitana 17

This boat is the first full size boat to be designed from scratch to use a foil system like the Fire Arrow. She was relaunched today and will soon embark on two transatlantic crossings to prepare for the Route Du Rhum starting Nov. 4th.
Jul 19, 2018, 02:35 PM
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I probably won't be able to sail D2 or Fire Arrow until sometime next year.........

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