RAFALE II
2016-2018
Catamaran class C
THE OBJECTIVE
The Rafale II project was born in the continuity of Rafale I. The objective was to design and manufacture a second class-C catamaran, in the school of higher technology and to be more efficient than the first. It was therefore necessary correct the defects of Rafale I: rework the various elements of the boat to reduce the mass, improve buoyancy, the rigidity of the hydrofoils, and rebuilding the damaged rigid wing in order to obtain a much more efficient vessel.
SHELL
The volume of the Rafale I hulls had been deliberately limited in order to reduce their weight as much as possible. The boat being made to fly, its flotation had been put in the background.
However, to take off, the boat needed to reach a speed of at least 10 knots. At low speed, the waterline being low, the crosspieces connecting the two hulls tended to hit the waves and consequently to slow down the ship : which is problematic in an acceleration phase necessary for take-off.
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A second problem present in many catamarans: the lack of volume at the front of the hulls. The boat then had too much of a tendency to sink, that is to say nose dive and sink into the sea and turn around. Rafale II's main mission was therefore to respond to these problems related to the buoyancy of the hulls. Significant design work has been carried out: increase the volume of the shells in order to float higher and no longer get into the oven.
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In addition, the structure of the boat lacked rigidity according to the skippers. There was particularly too much play between the transoms and the hulls.
It is known that the rigidity of a boat goes hand in hand with its ability to relaunch and accelerate. Thus, Rafale II had to be more rigid than the first prototype in order to improve its performance.
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To answer these problems, and, always with a view to reducing the total weight of the boat, the students worked on a new design and oriented on the use of prepreg aircraft-grade carbon fiber. Heating molds have been designed in order to be able to manufacture the hulls. Which was a real step forward in materials technology, because in comparison Rafale I had been made from dry carbon fiber infused with epoxy resin.
The new structure has made it possible to reduce the mass of the shells by 10% while increasing the volume and the rigidity.
FOILS
Although efficient, the foils of the first prototype were too heavy. They have been manufactured with resin-infused dry fiber and foam reinforcements.
The foils of Rafale II had been redesigned to improve their performance and above all reduce their weight. Thus, as with the shell, the pre-impregnated fiber has summer chosen linked to a reinforcement 3D printed: which allowed a significant reduction in mass and an improvement in overall rigidity.
THE WING
The Rafale I wing was very heavy. The mast of its structure had been made from a lamp post to reduce costs as much as possible, while having a conical shape specific to boat masts. The club therefore had the idea of designing a new wing, more efficient and above all lighter. However, the realization of this project never came to fruition. Thus, Rafale II is still sailing today with the Rafale I wing.
The competitions
Unfortunately, the competition which was the real raison d'être of Rafale II, La Little Cup, disappeared in a few months, despite having existed since the 1970s.
Thus, the C-class catamaran Rafale II has never been able to shine in fleet races with similar boats. However, Rafale II was still able to shine in 2 events:
-Miami Foiling Week (February 2018)
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Present at the Foiling Miami Weekend 2018, Burst It surprised sailing enthusiasts and curious passers-by with its imposing size. The catamaran respects the few rules of class C: 25 feet long, 14 feet wide, and 300 square feet of sail. These dimensions make class-C the largest coastal cruising catamarans without a cabin. Each hull displays the surprising weight of 43 kilos. During the construction of the ship, the fifteen students of the Rafale ETS team sought to save weight, gram by gram, to meet audacious objectives. Innovative techniques have been developed in order to respect the mass limits, such as the insertion of a 3D printed honeycomb core between the layers of carbon. The catamaran, however, being the only multihull on the water at the Foiling Miami weekend. It is therefore impossible to compete with someone similar. In addition, the manufacture of the foils had not been completed in time. The team was nevertheless proud to unveil for the first time on the water a prototype that had taken one year to design and one year to manufacture. So before flying it we just sailed it. Speeds of 13 knots in breeze at 15 nds have been reached without hydrofoils.
The team came back from this week of sailing with the boat broken at certain points, but happy with this experience. She had worked hard every night to make the boat operational for each new day. It took an average of 3 hours of repairs for 1 hour of navigation. The team then concentrated on making the ship more reliable with a view to winning future regattas.
At the same time, the club contemplated to develop its support: the manufacture of a 25-foot catamaran with hydrofoils required significant resources, and few universities were ready to embark on such a project. To tell the truth, the ETS was the only one to provide the necessary budgetary and logistical means.
-Montreal Open C-Class regatta (September 2018)
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From September 6 to 9, 2018, regulars on the shores of Lake Saint-Louis probably noticed at this time two large vertical wings looming on the horizon. The founder of the shipyard Vanguard, Steve Clark, and the Rafale student club from the École de Technologie Supérieure clashed during a friendly regatta, the Open C-Class Regata, thanks to the investment of former members.
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Both catamarans were cut out for racing: both equipped with hydrofoils and wings rigid for propulsion. The two catamarans pulled tight tacks while pursuing each other at 22 knots in a sustained wind at 12 knots. During one of the close-hauled legs, the Rafale team recorded a speed of 33 knots. This is the first time, after three years of construction, that Rafale II was flying.
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All the same, the game was not easy for the students: the American ship Cogito distanced himself from Rafale II at the end of each round. Poor hydrofoil adjustment prevented the latter from stabilizing its flight altitude and accelerating to the expected speeds. The ship would rise about twenty centimeters above the water and then fall back, while its American counterpart skimmed the surface during continuous flight edges. After all, the important thing is to fly and slow down as little as possible.
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The excessive speeds obtained weakened the pivot points of the rudders and the tearing of one of them. Throughout the night, the students were busy installing a new steering support. The ship was again ready to sail the next day. Despite a few lost rounds, the overall performance of the ship has demonstrated good maneuverability and flotation (such as resistance to being buried in the oven), all in a steady wind.