Tony holds the envelope during filling
(note the remains of the shroud)
This balloon mission, launched at 8:25 pm EDT on August 26 2001, was a second
attempt at setting a record for latex balloon flight duration.
The HamBONE-LD1 flight made second place in the
amateur balloon
mission records
list kept by Ralph Wallio. The longest latex flight recorded there (as of the date of LD2) is 5 hours 26
minutes, back in January 2000.
HamBONE-LD2 carried a payload package similar to that on LD1. It
included:
Unlike LD1, this flight was launched after sunset in order to
avoid the solar heating expansion which shortened LD1's flight.
The free lift margin was very small -- just 50 grams --
so we had to wait for an evening with calm surface winds AND light
winds aloft, to keep the flight in radio range.
The inflation phase went smoothly; we snipped the shroud material from the
ML-541A balloon envelope (it is designed for fast rising with an inverted
teardrop shape) and filled it indoors. It was fairly easy to achieve the
desired 50g free lift; we just poured 50 ml of water into a small plastic
bag and adjusted for equilibrium.
The launch had some anxious moments, as there was still some breeze an hour
after sunset and we were eager to launch. Initially, the balloon just flew
horizontally, so I gave it a push to get it moving upward. It then caught
a wind and headed around a house, clearing a tree by just 10 or 15 feet.
After that it was in the clear, and we all breathed a sigh of relief.
At the tracking station, we followed the numbers as the pressure slowly
decreased and the air temperature dropped. At 36 minutes MET the air
temp was 14C, down from 24C on the ground. I then turned the tape over
and did some cleanup. When I returned an hour later, the pressure was
back up to near its initial value, and the temperature was 20C ! Clearly
the balloon was not rising any more; it was slowly descending and near
the ground. I swung the beam and got a bearing before the signal got too
faint for DF. The total flight time was 1 hour 40 minutes.
I am transcribing the telemetry now, and will get a pressure profile for the
flight which might shed some light on why it came down. Obviously this
low-lift mode of operation is not as simple as it seems!
Update: 27 August 2001 - I got a phone call from a lady in Hillsdale, NY
who found the balloon and package! She saw it at about 9 in the morning while
driving by, caught in brush at the edge of a field. The envelope was intact
except for one hole about 1/4" in diameter. This might have happened on
landing, or it might have been an in-flight leak or a beak puncture! If it was a
puncture, the pressure in the
balloon was still low enough that it did not rupture completely. The kind lady
who found the package is sending it back, so there will be an LD3 flight at the next
opportunity.
Telemetry format (sent every 2 minutes) :
VVV DE KA2QPG/BALLOON LD2 UP #H ##M ALT ### OAT [NEG] ##C BAT #R#V AR
where:
UP = time since launch in hours and minutes
ALT = barometric pressure in random units
OAT = outside air temperature in whole degrees C
BAT = primary battery voltage in volts and tenths
Press this button for an email link:
Page updated November 27, 2001