Mar 10, 2013

Martin Fischer latest Projects & current Catracing foil Tech

Several posts on Martin Fischer on this website, as he is always open to talk and respond on any technical aspect. Beyond other big boat projects, Martin has now 3 World Champ F18 designs, and a few years ago he started a movement inside the catamaran racing scene aiming to go faster reducing wet surface through elevating the entire platform with his developed foil system. Although his first try, the Mayfly A, didn´t succeed, it triggered lots of new ideas and people went following the same path, with different views and trying to improve it, but basically they all have the same goal within a racing established cat class and now with ACup.

Photos Let: Flying Phantom , Franck Cammas helming (Udin), Paradox A-Cat ( Dario Valenza), GC32 (Chrsitophe Launay)
For him this initial system led to several child projects like the Flying Phantom. Udin recently has published a digitalized video version (to hide part of the foil design/setup) with the FP finally flying good. No easy task as reported by Udin, even beyond being outside any Class rule.

And also the GC32 , a 30' feet racing cat and recently a new A, the Paradox built by Dario Valenza.
His concept for cat course racing was conceived way before flying AC45s & AC72 we now are used to watch in awe.

'Disclaimer': Before someone starts saying that all has to be proven in course racing, please read every single post on this subject where I remark that, even first Mayfly post, also take notice that there is a reason why this website is called: 'Catamaran Racing, News & DESIGN', and finally read this interview where Fischer clearly points that this concept hasn´t won anything yet.
For those going on "but some other projects foiled before" read below, and please start to differentiate that foiling/flying/skimming/jumping within an established Class rules course racing it is a total different & tough game.

On the Cammas/Flying Phantom project he preferred to skip details for now.
Check his description on cat foiling types below, and also how he points out that as the AC72s will start racing on a reach/downwind leg (as seen in previous video), so I really don´t understand how some teams went and persisted to optimize upwind as a major and almost only winning card  without even testing foiling scaled down versions while knowing at the time that all the others were going, at least, to foil downwind and presumably fast in that first leg.

We are seeing history in the making with the AC72s and smaller racing cats, and no other group of people beyond us will able to tell their kids "I was there, I saw the whole process, and watched a great group of talented designers, builders and hardcore sailors being part of it, Martin Fischer was one of them"...
- CSN: Now we have foiling cats everywhere , and for a while since the Mayfly I've been trying to mark & differentiate foiling system like Hydroptere with current racing related projects including yours. 

How would explain the difference to gral public now that foiling has gone mainstream with the AC72? As for many even its all about the same, a flying cat...

Martin Fischer: Well I think catamaran foiling has not gone mainstream yet, but I am pretty sure it will very soon.

To categorise foiling boats we have to come back to the two main difficulties with a foiling sailboat:

1/ Heave stability (flight height)
2/ Pitch stability (longitudinal trim)

To obtain stable flight on a sailing boat that these two stability issues must be solved simultaneously. Contrary to heel stability - which is of course also an issue - I don't think that heave and pitch can be controlled actively by the crew. In order to solve these two problems there are two possibilities:

1/ Active control system: An active system to enforce a negative feedback
2/ Passive control system: An inherently stable system with a built in negative feedback

In both cases a negative feedback kicks in if the boat gets out of equilibrium. Furthermore the range of flight height and longitudinal trim is limited. The negative feedback and the limitation on the range of movement is either inherently built into the system or it is imposed by an active control system.
So I would say the way the negative feedback is implemented would be the first criterion to separate foiling boats into classes. A mixture of both systems is of course possible which makes the classification more complex. A few examples will probably clarify this type of classification:

1/ A-Class MayFly, GC32: pitch - passive, heave - passive
2/ Moth, Mirabaud : pitch - passive, heave - active
3/ Hydroptere : pitch - passive, heave - passive, but (to my knowledge) with
some active interference from the crew
4/ AC72: pitch - passive, heave - passive, but (to my knowledge) with some
active interference from the crew

And then there are inherently unstable configurations which may fly if they are in the hands of an experienced crew but these are limited to rather small crafts. Such examples are:

1/ Foiling surfboards and foiling kite boards
2/ A-Class without lifting surface at the rudder

Once one has found a way to create a stable configuration one has to decide for what purpose the setup should be optimised. The goals can be

1/ Just to make the boat fly - prove of concept
2/ To achieve maximum top speed
3/ To get the fastest boat around a certain course
4/ To get the fastest boat around a certain course and to fit into a set of
class rules

This offers a second possibility to divide foiling boats into classes.
Examples for the different categories are:

1/ White Dragon: A very nice boat with very stable flight, but to my knowledge it was neither designed for top speed, nor to be the fastest boat around a race course.
2/ Hydroptere, Icarus - designed for top speed
3/ Mirabaud - designed to win races around a certain course
4/ AC72, A-Class, Moth - designed to win races around a certain course and
fitting into the respective class rules

As you can see there are quite different concepts in terms of technology and
in terms of usage profile.

- Last week I published Raphael Censier flying/jumping... A , to my knowledge you were the first to fly a legal A , Do you recall any other project going for flights within a racing class beyond moths?
MF: I think Moth, A-Class, and AC72 are so far the only ones, and so far only the Moth has proven that they are quicker around the course than a non-foiling version of the same boat.

- It seems Raphael follows your projects on csn, he pointed out several links with them on the flight-jump discussion, must feel good inspiring young kids. When did you started your first project?
MF: We started first tests in Noumea about 6 years ago. But it was really a side thing. Olivier Schaller, a guy from Nouméa worked quite a bit on it.
The following link shows some of his early trials in 2008 ( on a heavily modified Capricorn. I started really working on the flying A-Class in 2009 I think.

Paradox A
- This year Dario Valenza is launching the Paradox, and you are responsible for its design. Which are the diff on this design/system from your previous versions?
MF: The principal setup is the same as on the MayFly, but this time we added a system to adjust the dihedral angle while sailing. This is important to get a good all-round boat. At low speed a small dihedral angle is advantageous, whereas at high speed a larger dihedral angle is the better solution. On the Paradox we think we got both.

>- Main Diff for L rudders against almost defacto Winglets in production As?
MF: To obtain positive pitch stability a lifting horizontal surface is absolutely necessary. The required size for pitch stability of the horizontal surface at the rudder can be computed from perturbation theory.
The main parameters that go into the equations are the surface of the main foil and its position with respect to the centre of gravity. This type of computation gives you the minimum size for a neutral configuration (pitch stability = zero) and then it is the designers work to add some safety margins to this minimum surface. It seems that I am more conservative in terms of safety margins than the other A-Class designers, since my L-rudders are significantly bigger than the typical winglets - to be seen.

A second point is the intersectional drag. The winglets form a sort of cross (+) with the vertical part of the rudder. This makes for 4 rectangular angles between surfaces and the corresponding intersectional drag. According to our simulations an L-rudder has less drag than a +-rudder for the same horizontal surface.

- The Paradox will be able to fly in high winds?
MF: Yes, I hope so

- I have reports from Mar Menor on 20sec stable flight on As, still all to be proven in the course, but this can be an exciting year, after many reasonable critics on your concept , now all following your path. What do you expect this year to happen in the A class?
MF: I think it will be a very interesting year in the A-Class. Obviously it would be even more interesting if the restrictions on foils that were introduced a few years ago were eliminated. These restrictions were voted after heavy lobbying of a rather conservative group of A-Class sailors. The A-Class has been a successful class over the past 40 years. Due to its open character the Class always could follow - or even make - the latest trends in catamaran sailing. In the current restrictions on foils this is no longer the case. The current restrictions were intended to make flying impossible - that obviously failed. Now they make things just more difficult and it could well happen that a new foiling class will appear that will make the A-Class obsolete.

- These reports on 20-30 seconds legal A-class flights with J boards, there is a limit on that conf opposed to yours, or they can theoretically manage long stable flights like those seeing in the F Phantom for ie?
I don't know the details of their foil setup but I don't think that it
is stable. Pitch stability may still work with the winglets but I am very sceptical about heave stability.

- What about the GC32, the boat look good & fast even without foiling on first videos, fast and smooth. Latest video shows a skimming flight but only in 12 knots. Happy with the performance so far?
MF: Yes, so far I am very happy with the performance and the behaviour of the boat. The design brief for the GC32 was to develop a state of the art racing catamaran that is fun to sail in light winds, but that can also be sailed in 20+ knots of wind on the North Sea (the CEO of the project lives
in Holland). Therefore we have hulls with lots of volume and a high freeboard, compared to similar boats of the same size.

- How is the GC32 reacting with more wind?
MF: so far the guys have been sailing only in Dubai, and the conditions there are light during this period of the year. But Macca reported so far a top speed of around 27 knots - during a gust - and that was without any problems.

- Any difference from the Paradox system or it is just an scaled version ?
MF: The boats follow the same concept, but they are different. Due to non-linear effects it is not possible to scale boats just up or down.

- Also Macca reported excellent behaviour in calm winds, is there more room for improvement? which is the final goal? foiling in 6 knots like the moth?
MF: No, this is not the goal, neither for the GC32 nor for the Paradox. For each boat there is an optimal take-off speed. In fact flying itself is not the goal. The goal is to minimise total drag (hull drag + foil drag) for a given speed and a given righting moment. This is actually an optimisation problem and we have worked on that. The optimal take-off speed for a Moth is very low, since the hull is very short and thus hull drag goes up very quickly with speed.

An A-Class hull has very little drag at moderate speed - less than a foil that has to carry the same weight - and therefore it does not make sense to try to fly too early. This optimal take-off speed is different for each boat and heavily depends on the length of the hull, the weight of the boat and the righting moment.

- I published some of your comments when Oracle was flying the 45s, how are you seeing the 4 teams now? Which is your favorite and why?
MF: Difficult question and I think I it's too early to answer now. I think all 4 teams are still in the game.

- Although another scale, you went through an interesting design process and progress with your 3 World Champ F18 designs: Capricorn, Wildcat & Phantom.
The first two , the best upwind performers F18s ever made, but both with extremely low margin for +20-25 knots downwind for inexperienced and even top racers.
Then the Phantom went to other extreme in high volume and downwind margin but with the same winning performance.
So at least in this scale I'm not seeing any worthy trade off to maximize upwind performance, plus the low aero drag goal of the Wildcat extreme raked bow you once describe in a csn interview.

Now that we have more info on the 72s and all will foiling, can this be related in a bigger scale?
MF: First of all the Phantom is actually a very quick boat upwind, so I think at least in the F18 class it is still very important to be very quick upwind. If you arrive only in 25th position at the top mark it will be very difficult to win the race, even if you are quicker downwind.

In the Americas Cup it is probably a bit different. There are only two boats and the courses are different with a reaching start. So I would say for the AC72 downwind and reaching performance has more relative importance than for an F18 boat.

- ETNZ seems also to have a super stable flight without external adjusters,can your system and L rudders be used/scaled up in an AC72?
MF: On the AC72 the windward foil must be pulled up within 20 seconds after a tack or a gibe (sailing instructions). The system I have on the A-Class needs both foils in the water, hence it is not possible to use it on the AC72.

 - This year you might have 3 of your projects flying, Paradox still to be seen , the GC32 and the Flying Phantom already airborne.
How do you feel now seeing the pinnacle of our sport using a concept you pioneer for course racing cats?

MF: I am not sure I pioneered it. I was probably one of the first to work on the concept for an international racing class with a high level of competition, but so far no major title has been won with a foiling catamaran.
I am convinced it will happen - probably soon - but it still has to be proven.
As of the Americas Cup I am obviously thrilled seeing these big boats fully foiling. I think this will give a big kick to beach catamaran sailing and I am pretty sure the beach cat scene will soon change quite significantly.

- What about Jessica Rabbit, that wild Tri you once sent me images of her launch, you reached 40knots? It flies too ?! Why you used T rudders on that Tri instead of L ?

MF: We haven't reached 40 knots - that probably would be a bit much for a 40ft trimaran - but 2 weeks ago we hit 33.1 knots in 20 knots of true wind speed. The boat does not fully fly, but it is very close to flying. I reckon that the foil and the T-rudder carry between 80% and 90% of the total weight when she is on here foils. At high speed the boat is very stable and she never feels dangerous.
Upwind in stronger winds (20 knots) the boat is surprisingly fast for her size. In fact the foils are very big for the size of the boat and in these conditions the boat steps literally onto the foils when sailing upwind. The effect is an immediate jump in boat speed and pointing angle.
We went for t-rudders mainly for structural reasons. For a bigger boat the loads can become pretty high and with a T-rudder the maximum bending moment is reduced by a factor of 2 compared to an L-rudder.

- Finally, I'm a little 'worried' now about the future, as in this year end we might have winning flying boats in the ACup and AClass... and Cammas Flying Phantom is an 18 footer what is next????? BP VI Flying around the Globe?
MF:Well, why not ...

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