AC72 Rudder Wings

Dear all,
I'm trying to understand more about trim and the stability of an AC72 foiling Catamaran. Specifically, what about the lift acting on the rudder wings ? Is it pointing upward or downward ?
Thank you very much for any help you may like to offer.

 

Ac 72

AC 72 rudder foils couldn't be adjusted when racing so they likely worked similar to other foiler rudder foils. The Rave foiler is set up with zero angle of incidence on the rudder foil and +2.5 degrees on the main foils. When the boat takes off the rudder foil lifts vertically but as the boat speeds up and pitches down the rudder foil will begin to pull down automatically.
Hope this is some help.

 

thank you very much for your answer.
So, when flying on foils with hulls outside water, an AC72 could control pitch moment only with daggerboard rake angle. Is it true ? i.e. if rudder is set to 0 incidence, the only contribution to righting moment comes from daggerboard lift, and rudder wings only provides stability and doesn't contribute to trimming?
thanks

 

The rudder foils automatically contribute to pitch stability throughout the speed range. Daggerboard rake angle was primarily used to set altitude for a specific speed range which depended on the foil design and heave stability of the foil. In 34, foils varied from straight "L" to uptip-the higher the tip was up the better the heave stability and less rake adjustment was required. Some rig adjustments also contributed to pitch stability.
PS- the daggerboard/uptip foil did not contribute to righting moment.

 

thank you a lot for your answer

 

Hi! I am now trying to perform a preliminar calculation of the longitudinal righting moment (along boat pitch axis) of an AC72 catamaran in a trimmed foil flying condition. What are major terms to be taken into account in a preliminar estimate of the longitudinal righting moment?
thanks a lot