I am going to build a bipe with wingspan of about 40 inches. It is going to be powered by an os max .46 la. I have got 4 standard servos 2 hitec HS-81s and 1 Hs-55. Which should I use and for what?

Listing where your best servos should be from most important to least important. Rudder-- Elevator--Ailerons--Throttle.
later David