Steve wrote: How close to the rear of the forward spar should the back of the tank be?
Steve, I have aluminum tanks in my outer wings. They run almost to the tips. Inboard they are 14 inches aft toward the rear spar and outboard they are nine inches deep. My tanks are almost right up against the forward spar, with the 1/4" space between spar and tank side being filled with expanding foam. This helps keep the tank in position and prevents chaffing of the two. Baffles for long tanks are a must. I have two in each tank. Without them you are at great risk in uncoordinated flight of your plane becoming unbalanced and difficult to control. As far as CG, my plane does not move more than one third of an inch between full tanks and empty ones. I usually do not have to make more than one or two small trim changes on a long cross country flight due to shifting CG. If you make your tanks so they go all the way to the aft spar this probably is not the case, but that is opinion. Have a joyous Thanksgiving. IHS, Dave "Zipper" Goodman Vertical Avionics, Inc. www.verticalavionics.com
