I am planning to do a high altitude balloon launch and I was wondering if anyone on this forum could help me figure out a few things. The payload+the balloon+the parachute= weigh around 2 pounds. I am looking to get 3 pounds of free lift (each pound of free lift equals 300 feet per minute accent). I believe that one square foot of helium can lift 28grams. The balloon that I am planning to use is the KCI 800 from this site http://kaymont.com/pages/sounding-balloons.cfm [Broken] it has all the details about the balloon. I am looking for the amount of helium that would be required to lift that weight at that rate, and I am wondering what the diameter of the balloon should be so I know that it is full. Your help will be greatly appreciated, Thank you.