Feb 12, 2014

'Stunt 9' by Michele Petrucci: Optimizing foiling out of the Box .. rule

Updates from Michele Petrucci on his S.9  . A really cool downsized A-Cat, capable to foil using a double Moth wand system. We had a chat with Michele and I asked him why not going for the AC72/FPhantom or the A-Cat solution, that at first glance, and at least on the FP, they seem simpler than his Moth x 2 complex style setup. I wouldn´t like to have this on an A or even the cassette case so to speak, the simpler the better.
But Michelle feels (and tested) that foiling is easier and you don't need to be Nathan Outteridge or Mischa Heemskerk to get airtime and in full control. Vid footage looks impressive, waiting for rib cam though.
The S.9 can be sailed standard floating mode too. Below Michele talking about this great project to be offered as a production boat soon.
Contact Michele facebook.com/catamaran.stunt
Michele Petrucci: "The S .9 had a little delay due to the new models and molds, but in about 1 month we are going to be able to test the first production series.

I've read many of your interviews and some comments and I think there is much confusion in the minds of the A-Class builders & designers.
Since 2008 I made my first flight with an A Cat. I made lots of  otw testing with different types of foils, so I have a very good understanding of the  advantages and disadvantages of each type (J, C, L, T, foil rudders).

I noticed that other builders do not have a clear idea on the advantages of each system
From personal experience I can make a bit of certification on the foil setups:

- L Foils
Must absolutely be accompanied by an automated system ( Wand ) as the push up out of the water , for self-leveling without automatic systems the most suitable are the Curve daggerboards .
An extreme design like the 'L' increases the difficulty of height control. 

With a more standard design like the 'C' the flight is more constant and regular but you  need more wind to start flying .

- J Foils
Middle solution between L and C daggerboards, they are like Curve daggerboards but provide a greater height and lift than the C,  but this solution increases the difficulty of height trim.
With a less extreme design ( such as Curve daggerboards ) the flight is more constant and regular but need more wind to begin flights.

J Foils remain the compromise performance solution, however, each designs has a dedicated range of use ( wave and wind) With the system used in the  Moths and on the S .9 you will have the best of both Worlds, with a wider range of use.

CSN: What about the A-Class? I've seen in pics some strange draggy looking foils from Takapuna. I do hope that the best all around solution to arise from these worlds. A good 5knots couple of races will kill any foiling wannabe in my view.
MP: To have an efficient foiling the most important thing is to test all types of foils, and to understand the behavior over the entire range of wind & waves.  The last flights with boards C and T rudders I made 2 years ago with the Stunt 12 was the best solution.

For the As it might work too, but it was not that satisfactory in so

me of the tests I did. Last year I tested T boards without wands that were really much high performance than the Cs of course, but the flight was not constant, so I applied the Moth wand system  and I'm 100% sure that single handed Cats like an A / S.9  must have an automatic regulation system to be able to fly always in every wind-wave condition. 
All other foil systems will not offer efficient Course racing.

I believe that the best solutions found for the As are from our dear friend Glenn Ashby, the maximum size of the T rudders and Js boards, everyone else is using rudders with too small wings.
In my opinion, I would use even the mast up to 8-8.5 m, as soon as I have time I begin work on my class A, perhaps at Easter I'll compete with it.

CSN: Why you didn´t go with the Phantom/TNZ solution for the S.9? I realize with yours you might fly earlier but still you have a lot of equipment with the wands and else. If Ashby is flying as Arno is reporting then it is not the best simple and efficient solution around ?? Your might have a higher degree of automatic control for newbies and less skills will be required for your setup, but it's still more complex.
-MP:  The FP solution is not appropriate for a single handed cat. Their foil do not have enough lift and need to create a lot of speed in order to fly, in fact, the FP does not a good upwind performance in my view.
Flying with 12 knots of wind at 55 ° from it, 55 is too much, it is not optimum for course racing.

Gaining maximum speed is not the right way, on the S .9 we have a greater foil surface  area, just like the Moth. This added lift slightly reduces the speed but gives us very controlled flight even in winds of 8 knots upwind and at an angle against the wind almost equal to the A Class.

Catamarans have always been about speed so I did not wanted to design a speed machine but a cat easier and more stable, an all-round.
Another important factor is that on the S .9 you must not pull up the board upwind, while all the other flying cats are forced to do this,
If you analyze the movies you can see that it is easy for the crew to fall into the water due to the configuration with 3 foils, the .9 s has 4 thus more stable.

The wand system is complicated to build and to adjust, but when you've found the right setting it does not have any additional problems crew work is very little. In the top plate adjustment of the boards I applied a wheel to make small adjustments while sailing.

I can also add that the S 9 is designed to be fully interchangeable and easily disassembled, each part can be removed in a short time, this allows us to reduce the cost of handling and maintenance, but also allows us to create different configurations and varied, all the wings can be disassembled with a screw so you can use different designs. All this gives you an easy and economic future evolution but also to configure the boat to our liking based on the needs of the crew.

The S .9 was born as a no-fly boat, it is a semi-planing and in 5 minutes you can remove the wings and use this boat in the old style, when the wind is too high or too low so you can still sail , even race.

I think it's a great boat which you can start an evolutionary path (without having to buy a new boat), starting with an old floating style and then change to the Fly mode gears, With a depowered rig is also great for kids, S.9 is designed to crews from 40 to 85 kg".

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