It says the dimensions of the 750 lb Fly High sacs are 50 X 20 X 20. The Launch pad 540 lb sacs are the same dimensions (I think). So how can they be the same dimensions, yet the Fly high holds 210 more lbs of water? <BR>By the way, I'm looking for a couple Fly high 750 sacs if anyone has one... or two.

the dimensions likely are not the same. <BR> <BR><a href="http://www.metric-conversions.org/volume/cubic-inches-to-gallons.htm" target="_blank">www.metric-conversions.org/volume/cubic-inches-to-gallons.htm</a> <BR> <BR>One gallon of water weighs 8.33 #s. 50 X 20X 20 comes out to about 721 #s. so the fly high figure is pretty close

plus that sac will bulge to around 52x21x21 which will put you well over 750lbs.

I have found the Fly High sacs will be a little more than rated when they are full. The bulge makes a difference.

So its true? The bulge does make a difference? I thought it was how you use it.

hahahaha hate n pain that's classsssic.

Fly Highs are square and the Launch Pad is round so you loose some space for actual cpacity even though the dimesnions are close to the same. The diameter is 20. Different formula for a cylinder ;) <BR>Easy to see. Draw a square 20X20 and draw a circle with a diameter of 20 inside of it. It will touch at four points(the center points of each side) and will have some open area on all four sides. The true Engineering geek in me has yet to go away. While it may seem the same on paper with numbers.......it is far from the same un actuality. <BR> <BR>But you can't argue with the buldge <BR> <BR>(Message edited by xstarrider on April 29, 2009)

Swatguy is right on the mark. <BR> <BR>I think I am going to design a ballast bag based solely on the bulge. Maybe just super elastic to squeeze into every single little nook n' crannie in the compartment. The perfect use of space.