1 cubic meter of helium at sea level has a lift of about 1 kg, and 1 cubic meter of helium is equivalent to 35.3 cubic feet.
The ballon had a capacity of 1570 cubic feet. Divide that by 35.3 cubic feet it had 45 kilos of lift or 112 pounds minus the weight of the craft. It had enough to get the boy up.
right ... ~105lbs at sea level. At 5000ft it’s about 96 lbs of lift.
It came down without a kid in it how could it taken off with him in it?
“1 cubic meter of helium at sea level has a lift of about 1 kg”
Right, but that is at sea level. Denver is not at sea level, it is about 6,000 feet up. Not sure exactly what the capacity is at 6,000 ft, but I found this chart, that places it between 0.35 and 1.00/m3.
Altitude (m) Altitude (ft) Buoyancy (kg/m^3)
0 0 ~1
10,000 32,000 0.356055
20,000 66,000 0.076556
30,000 98,000 0.015852
35,000 115,000 0.00728742
Also, consider that if the craft was near its peak load when it was on the ground, it couldn’t possibly reach anywhere near the peak altitude of the unladen craft, it would top out at a much lower altitude and hover there before starting to sink.