I don't know if they are needed, but I put them in the Sledge, and it's not a comp, just a FF. I just wanted to see how some .10 speed/100oz-in servos would feel in a FF plane. I should have modified the aileron mounts to be able to get the servos out without cutting the upper wing covering, but hey, I already had to cut it to put them back in , so one more won't hurt I guess. Running a 720MAH 5 cell NiMh pack.