Balloon Bomb - Smithsonian Institution Libraries

Of the 80 tons of hydrogen programmed, 50 tons
were to be compressed into 97,500 cylinders and
transported to Nakoso and Ichinomiya, while the
remaining 30 tons were piped directly to the launch pads
at Otsu. Considering the refueling of the gas cylinders,
20,000 would be needed; however, by late
December—well into the launch program—only 8,000
cylinders were on hand. Consequently, the number of
balloons released in November and December fell
considerably short of what had been programmed.
Though release of 150 balloons a day was the combined
schedule for the three launch sites, about 30 was the
actual figure.
A rapid shuttle system of empty and filled hydrogen
tanks could have met the demand, but the frequent air
raids against the rail lines immensely hampered the
transportation of the gas.
The 1st Battalion at Otsu utilized hydrogen that was
generated from caustic soda and ferrosilicon in the
following formula.
2NaOH + Si + H 2 0 = Na 2 Si0 3 + 2H 2
This required more than 2,000 tons of caustic soda to
launch 4,000 balloons. The requirement of ferrosilicon
was in the same proportion required by the formula—no
small amount.
Fire was an ever-present danger and not an uncommon
occurrence at the launch site. Hydrogen mixed
with oxygen became highly inflammable, and was even
more dangerous when heated during the transfer operation
while filling the balloon. Attached to the base of
the balloon was a paper-made, 50-centimeter-radius
hose-20 to 30 meters in length—connected to the
rubber hose which led to the gas-supply chamber. This
rubber hose could be crimped off quickly at the first
sign of fire. Men with buckets of sand were always
poised to extinguish the first flicker of fire, while others
would quickly turn off all of the gas valves. Stock piles
of incendiary and high-explosive bombs, paper balloon
envelopes', and hydrogen tanks provided a constant
threat of fire and destruction at the launch sites.
Inflating and Launching
The methods used by the Japanese to inflate and
launch the A-Type and B-Type bombing balloons were,
for all practical purposes, similar. The discussion which
follows applies particularly to the A-Type (paper)
balloon.
An inflation bed was prepared by sinking 19 screw
anchors into the ground as shown in Figure 81. This was
followed by laying out the balloon within the screwanchor
circle, connecting the inflation tube to the
inflation appendix, and securing the suspension bridles
to the open eye of the screw anchors. The inflation
equipment—including inflation tubing and manifold with
high-pressure hose—were the same as those used for
barrage balloons. Two cylinders were emptied at a time.
Approximately 8,100 cubic feet of hydrogen were
required for inflation and launching. The method used
to determine the amount of gas supplied to the balloon
is shown in Figure 81. Approximately 860 pounds of
buoyancy was attained before release.
After removing the inflation tubing from the balloon,
the gas valve was installed. Long ropes with an eye were
reeved through each loop provided in the suspension
curtain and hooked to the eye in the screw anchor. The
suspension bridle was then removed. During this operation,
one crewman alongside held the balloon in the
position shown in Figure 81. Following this, the
equipment was installed and the balloon allowed to rise
until the equipment cleared the ground. The instruments
and other equipment were checked and half of the long
ropes were removed from the balloon. The long fuses
were ignited, followed by unhooking the long ropes
from the screw anchors and the balloon was released.
The crewmen held onto one end of the long ropes. If the
rope moved easily through the loop in the suspension
band, it was recovered; if it became entangled, it was
released and allowed to ascend with the balloon. This
method of launching was used only when the surface
wind was mild.
When the wind exceeded two and one-half miles per
hour another method of launching was employed. The
balloon was inflated in the same manner as previously
described. Instead of using long ropes to raise the
balloon in order to suspend the equipment, the balloon
was held in position close to the ground until it was
launched. A launching sandbag arrangement, as illustrated
in Figure 82, was secured to alternate suspension
points on the balloon and corresponding screw
anchors on the ground. The equipment was suspended
from a tilting arm on a wooden stand as shown in Figure
82.
At a given signal, the balloon was released from the
screw anchors. It ascended, carrying with it the paper
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