Two Get Very High (Part 1)
Two get very high - Part one.
So there we were, 30,000' upside down, nothing on the clock but
the maker's name. All good flying stories should start with a
line like that. For Lev David and I, it was sort of true.
Topping out at 30,334', briefly we were the highest people stood
outside anywhere. We shook hands and the feeling was humbling
and then we had to return to a pressing need. Relighting the
pilot lights, they had gone out 834 feet beforehand. I knew that
the chances of getting them lit before we had dropped below
25,000' were slim - the balloon factory in England had told me
so!
The story began as so many do in a Beer tent. Splashy Fen 2004
Underberg Kwa Zulu Natal. I had met Lev David, producer and
presenter of East Coast Radio's breakfast show a month or two
earlier. He stood on top of one of my balloons at the ABSA
Stadium Durban. I was very impressed with his fearless manner.
Live on the show they had spoken via sat phone to a climber on
top of Kilimanjaro, Lev asked if the balloon could get higher
and I said of course. Reaching the height of Everest at 29,000'
and a bit seemed the way forward. With my beer head on, I had
said the balloon could do it without really thinking about it.
What would it matter we both would have forgotten the
conversation by the morning.
The conversation was forgotten but only for a couple of weeks.
When revisited in the cold light of day, the problem of getting
the balloon to height did not seem insurmountable. A quick check
of the manufacturers slide rule load calculator proved that two
of us could easily get up to 15,000' with a couple of hundred
spare kilos of lift in hand. Sitting down with the formulas
would be required for an accurate idea of what we could lift
higher. Time to ask grown ups for help.
I have a friend in Australia, Steve Griffin who makes a habit of
taking small balloons to great heights. He holds several world
records for one-man balloons and has even gone to the Arctic in
order to get into efficient low temperatures. An email to Steve
provided an excel spreadsheet which I had to modify slightly as
he can't get much above 18,000' in a hopper. It had the maths
sorted though. I ran the numbers and worked out that we would
have at least 40Kg of spare lift at 30k.
Working the old saying, measure twice cut once, I checked with
another grown up, Simon Forse, the technical guy at Lindstrand
balloons in England. He sent this jaunty equation, based on a
180 at an internal temp of 100C
L = p x V Therefore L = V x p0 Im = 3.28084ft Where for 30Kft =
9143m or 9500m P0 = 0.43890 kgIm3 T0 = 226.4 0K V = 5100m3 T1 =
100 0C or 373 0K 0.60697 L = 5100 x 0.43890
L = 5100 x 0.43890 x 0.39303
L max = 879kg
Ok so we could certainly lift the two of us.
Getting into the stride of things it was time to address the
environment in which we would be operating. The Internet, modern
source of answers to everything quickly painted a picture. We
potentially faced temperatures of -60C in 110 knot winds
generally from the North West. I knew it was going to be cold
but -60! The wind speed mattered not, other than selection of
launch site. As long as it was slow for the landing.
Every 18,000' that you climb halves the properties of the
atmosphere at sea level. We would be operating close to