Launched 2 balloons at 6pm within 2 mins of each other. Balloon was a 30g 3ft diameter Latex balloon (Qualatex) filled to 22" diameter and with 60g of nozzle lift. Payload was 30g, ascent rate was around 1.2 m/s for most of the flight,
but the flight leveled out at 26000f, around -30C.. Both balloons behaved the same.
A previous flight a few weeks earlier with the same configuration and 20g (i.e. 10g less) payload, burst at 53,800 ft.
Is there any scenario in which a small latex balloon that is positively buoyant with the addition of 10g of weight could result in a floater?
We've ruled out ice accumulation. We don't think radiant cooling (it leveled out around dusk) would be enough
to cause that, and as it's 2 balloons, it's unlikely they'd be a slow leak at the same rate on both.
Only thing left I can think of is it was in sinking air at the same velocity as the lift. My understanding is
floaters only happen if the envelope can't stretch any further and doesn't burst (which doesn't typically happen to latex) , or the balloon is so big and the fill so minimal.