On the last couple of flights I have been using 6psc of 38x19mm-solar-cells connected in series, I know from looking at Daves u3b flights photos with th new u3b firmware he use the same cells but cut in half,?from various reason I would suggest you to buy both sizes of cells, 38x19 & 52x19.
I fill the balloon just a little bit a the time, its just a "sip" of gas that gives you 1 gram of extra lift, as the gas is in the top of the balloon, (its realy just filled by 10% or so) it wont get out as you try the free lift between fillings, even as the clear Ali balloons dont have a self sealing hose, and as its lacks this just push out som gas if there is to much or use a straw and suck it out (be carefull).
If you ever going to try a qualatex use a paper straw to suck out excessive gas as any plastic straw will stick to the selfsealing in the filling hole and you will destroy it.
/Mikael
