ike, first of all, AWESOME! what camera did you use and man you better post that video! i would love to see that. upload it as an attachment if you have to!
mopeder, what kind do you have and about how much playdough did u have to add?
silverfox, awesome thanks man! now i can do the real calculations when it comes time to build the final one.
i just bought a couple 3 foot balloons and a 1 time use helium tank that fills 50 regular sized baloons for 35$. just gonna attach the internals from a cheap 15$ radio shack rc plane and see where that gets me.