Hydrofoil trimaran

Greeting and hello to everyone

First of all big thanks in advance for everyone who give they opinion and help on this matter . I m trying to design and build hydrofoil trimaran for school project wich would be powered by internal electric motor . I have some basic knowledge of foilers from Ray Vellinga book also i m on the 5 th year of college and representing myself and my team so we have some background in current topic ....We designed some inicial project with basic caracteristic :

-lwl=2.35 m
-b=1.75(from ama to ama)
-d=0.45 (main hull)-big depth in for different disciplines
-Foiler configuration : canard
-forward foils : surface piercing-2x position wide abeam on amas
-main foils - t foil on rudder
-NACA: 63-412 on both forward and aft wings

Our goal is to register for internacional competition in three disciplines so our boat must be able to do displacement (or semidispalcement ) transfer of 200 kg and two so to say more speed races on the 200 m track ( rectangular track with sharp 90 deg turn on each corner )

-My question are ?

-foils configuration goog/bad(t foil carries cca 70 % weight)

-does main t foil needs addicional hight sensor in current configuration with forward surface piercer ( i think not cuz forward foil will change AOI of t foil , and currently we are not planing to put any addicional height sensor)

-i was unable to find trimarans foilers WITHOUT sails , also i m concerned about turning manuvers of this ship (shown on pic below) , but i also saw very good flat turns manovers in similar configurations.

-in order to find balance beetwen weight transport and spped races our first choice is semidiplacement main hull??(what do u think of this)

-ama design -do they need to have same depth as main hull to provide inicial stability when boat is on the rest or they can have smaller depth like on pic below?

-ama design -how long they can be in compare to main hull and what cross section do u recomend ?

-roll menagment by two forward dihedrals ?

*** pic below was made for purpose of marketing
*** neglect shape of hulls
***forward foils are going to bi relocated on outer side of amas and on cross bar conecting to main hull
***neglect dimensions between forward and aft foil



Big thanks in advance.

 

Hi sub_0,

As a first thing, I would suggest you to join the two tips of forward foils and to create one single V-foil canard. The wing tips are a source of vortex drag, so if the competition is about the endurance and max. speed for a given power, you better start removing everything that might create more drag than necessary.

The weight will be of critical importance too - which means that materials and construction methods have to be carefully planned.

The longitudinal position, spacing and angles of attack of both the main wing and the canard have to be determined through calculation of static and dynamic longitudinal stability, the methods for which are well-established in aeronautical engineering. The roll stability will be determined in the same way.

Regarding the design of the hull and the amas, it will depend on the mission requirements. How is the "weight transport" competition defined? Does it require foiling or is it done in displacement mode? What constraints are imposed by the rules?

Generally, during the boat acceleration from rest, the hull will be very load-efficient at very low speeds, the foil kicking in above a certain speed (the exact values depending on your hulls shape and displacement). So the analysis has to take into account this trade-off.

PM me if you need help in this analysis.

Cheers

 

Thanks on reply

Yes we considered joining front foils due to vortex and strenght problems however we decided to secrifice that . Why ? we are planing on developing flexsible design that will alow us more moving parts in order to correct possible mistakes. Front foils are not join to allow traslation both of amas and foils towards or outwards of main hull .

The material will be carbon fibres and since boat has to carry MIN of 20 kg at all time we calculated total mass around 42 kg .

Weight trasnport will be without foils.

For dynamic analysis we are trying to run numeca , strenght analysis will be conduced using femap .

For the main hull we are thinking of choosing semideiplacement hull .

Is there any sort of papers or low requirements software (done excel sheets etc. ) for preliminary calculation .