Pre-flight building / testing

Russ's finishing touches on Ivory 4.0 / Bottle 1.0. He reports that it's 96 grams fully assembled.

1 cm of pink foam is our "ballast cut down mechanism". We'll tie ballast to it, and the phone will decide to drop it under an increasingly complicated set of circumstances.

Also notable: Gamma matched Yagi antenna. There's 50 ohm Coax (black) running to the "Driven Element". The driven element is grounded to the coax shield. The still-shielded antenna wire then passes into a short length of aluminum tube, which is capacitively coupled to the driven element. Then witchcraft happens, and the RF knows to go towards the directors and away from the reflector, unless it's GPS, and then it'll go the other way.

Without the gamma match, we'd need a (heavy / more complex) "balun" to match the balanced dipole of a Yagi to an unbalanced feed from the cell.

Smile! This balloon weighed 31 grams empty, had 50 grams of lift when full and we'll probably launch it with 25 grams of lift. (70% full means we'll rise until the air is 70% less dense, about 12,000 feet. Then, the balloon will start building pressure until it levels off at 14,000 dark, and maybe 16-18000 in the sun. Fingers crossed.