TOdo: update me with what we are really going to do.  no buckets?  No barn?

stolen from http://www.eoss.org/pubs/faqloon.htm

"

FILLING THE BALLOON

Fill the balloon indoors or in an area that's very well protected from the wind. You don't want to have to fight the wind because the balloon is very fragile and it will burst. Look for an old barn or airplane hanger. Be aware that the balloon will just barely clear a barn door when it's filled. A home garage door isn't high enough.

Spread a tarp on the ground to protect the balloon and spread the balloon out on the tarp. Handle the balloon with gloves.

Lay the gas tank next to the balloon. (It can't fall over if it's laying on the ground.) The regulator manufacturers recommend that you crack the valve slightly to blow out any dust before screwing on the regulator. Be aware that the threads on hydrogen tanks are "backwards" - you turn them counter clockwise to tighten them. (This gave me a bad moment on my first solo launch.) Run a hose from the regulator to your filling adaptor.

THE FILLING ADAPTOR: This is a piece of plastic tubing wide enough to be a snug fit into the open end of the balloon - 1.5 to 2 inches should do it. PVC pipe is fine. Somehow neck the other end of that tube down to the point where you can attach the hose from the gas tank to it. Also put a hook on the tube - perhaps by epoxying a piece of coat hanger wire to the side of the tube, near the end where the hose attaches. Now tie some twine from that hook to the jug.

Start the gas flowing and the balloon will start to inflate. Try not to get any air into the balloon, especially if you're using hydrogen! When the balloon lifts off the ground, the jug of water will keep it from going anywhere.

Continue to fill the balloon until the jug "just" lifts off the floor. You now have enough gas in the balloon to lift your payload, parachute, radar reflector and connecting cords plus the extra six to sixteen ounces of water you put in the jug.

Sealing the balloon: using heavy twine, tie the balloon neck off tightly above the filling adaptor. Remove the adaptor. Tie the neck again, four to six inches below the first piece of twine. Tie your payload cord to the neck between these two pieces of twine. Now bend the neck over double and tie it again, twice. You will now have the neck of the balloon bent over double, with the payload suspension cord nestled in the bottom of the bend and the whole thing securely tied. You're ready to launch. (You can use tie-wraps instead of twine if you wish, but they're heavier.)"

Solve: How to shelter or restrain balloon while filling

Above info states that balloon can burst with stress of fighting the wind.

Do we have enough helium to fill two balloons?

Will restraining the balloon with a 4-point tethered net or tarp actually cause more stress to the balloon than taking the risk of just filling in the open?

Solve: Anchoring balloon+filling adaptor while filling

Attach anchor device to filling adaptor. When anchor begins to lift, balloon is filled with correct amount of helium

[anchor device is exact weight of final payload & rigging] + [extra weight of hose & filling adaptor] = weight/amount of lift desired from balloon fill

(does this sound right?)