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sink-me
Windjammers of the Sky
Some mysterious force in the atmosphere had taken charge of the big free balloon
and was treating it like a child's rubber ball.
The student pilot in the wicker basket below the bag was worried. He had been
ordered to take it up to the 500-foot level but every time he rose to 150 feet something
batted the balloon earthward again. It rose and fell as if it were bumping along
in slow motion under a solid roof.
Lt. George N. Steelman, free balloon officer in charge, grinned and explained
the trouble. He told his student crew "There's a stratum of air of different temperature
overhead that won't let us through. Spill out two handfuls of sand and see if that
helps."
It did. The few ounces of ballast that were tossed over the side lightened the
balloon enough for it to ascend steadily through the layer of air. At 500 feet the
craft encountered a northwest breeze and began to drift along toward San Jose.
Free balloons are the sailing vessels of the air and free ballooning is a sport
unlike any other in the world. But Navy Balloon No. 03546 was not on a pleasure
cruise this trip. Lt. Steelman's crew consisted of naval aviation cadets who were
learning to pilot the Navy's big anti-submarine patrol blimps. Free ballooning is
the basis of their education. Their ability to maneuver the two-engined blimps depends
on how well they learn their lessons in lighter-than-air. In case of engine failure
they could use their knowledge to handle a blimp exactly like a free balloon.
You might suppose that a balloon is at the mercy of the winds. But at such lighter-than-air
bases as Moffett Field in California the aviation cadets learn that this isn't necessarily
so. They learn that within reason they can maneuver a balloon to travel in any desired
direction and that not infrequently they can bring it back to land at the spot from
which it took off.
Basket of free balloon at Moffett Field gets change of crew. Below, instrument
box for navigation boasts altimeter, clock
Pressure of the hydrogen gas within distends the balloon into a perfect
sphere. Right, inspecting "appendix" left open in flight
By now Steelman's balloon was over San Jose and he wanted to change his course
to the west. He started fishing for a wind. Over the side he dropped small pieces
of tissue paper and watched them as they streamed one after another toward the ground.
Halfway down they veered toward the east. There was a wind down there but it was
going in the wrong direction.
Down for lunch, balloon crew "walks" basket along highway
"Out two handfuls," he ordered.
Two handfuls of sand went over the side. There was no sensation yet the bubble
on the statoscope instrument that shows changes in barometric pressure indicated
that the balloon was rising. At 1,000 feet the balloon's shadow on the ground started
to move toward the west. Steelman had the wind he wanted.
"Valve one second" he directed. A cadet pulled on a line, opening the valve at
the top of the bag long enough for one second of hydrogen to escape. That leveled
the balloon off at the new altitude. Free ballooning seems like a quiet, peaceful
sport and yet there are a hundred and one tricks that Steelman must teach his students.
Every bit of knowledge that he can impart from his 2,000 hours of experience in
flying and racing the big bags will aid them in their careers.
Hydrogen storage flasks are anchored in concrete holder
A free balloon moves with the wind, so except for an occasional flurry when the
wind changes direction, the bag seems to remain in a dead calm. And there is no
sound from its flight. The creak of the cordage, the patter of the carrier pigeons'
feet in their wooden box, and noises that rise from the ground are all you hear.
Still, free balloon enthusiasts have a few wild tales they can tell, such as
the time when Lt. Steelman found himself at the mercy of a whirlwind. His balloon
began to spin around as if it were attached to the periphery of a merry-go-round.
The basket and drag rope were streaming out almost horizontally. Gas spilled from
the open appendix so rapidly that the balloon was sinking in spite of all the ballast
that was released. The wild ride ended safely close to the ground where the cyclonic
force of the wind was weaker.
The most thrilling adventures of all were back in the days of the international
balloon races. These races were for the greatest possible distance and so the two-man
crews let wind and temperature take charge, hesitating to valve out even a second's
precious gas at any time. In spite of the fact that they knew they would encounter
sub-zero temperatures at high altitudes they usually wore nothing but shorts, to
save weight.
Steelman and Capt. T. G. W. Settle starved themselves down almost to skin and
bones for the 1928 race and refused to carry an oxygen supply because of the weight
of the containers. They were carried up to 18,000 feet and then a thunderstorm took
charge, lifting them up to 21,000 feet and then dropping them down again at so great
a speed that they passed bags of sand that they had tossed out a moment earlier
to prevent just such a descent.
The Navy's training balloons are of 35,000 cubic feet capacity and are inflated
with hydrogen because of its great lifting power. A pilot, first and second sandmen,
log keeper, and valveman make up a crew. Thirty-one bags of sand, weighing 30 pounds
each, are carried as ballast, permitting several flights to be made during a day
so that several crews may receive training. The balloon's basket is also fitted
with the statoscope instrument, a clock, and a 225-foot-long drag rope. At low altitudes
over hilly country the drag rope can be used as automatic ballast, for the balloon
is relieved of the weight of as much rope as is allowed to drag on the ground. Thus
a pilot who is dragging part of his drag rope over the ground can climb when he
encounters a hill by paying out more rope, hence lightening the balloon, and if
he wishes to descend the other side of the hill he retrieves enough rope to cause
the balloon to settle.
Spilling sand ballast over the side to speed ascent of balloon. Below,
landing in field as blimp watches
Ground crew "walking" balloon out of hangar. Pulling on rip cord (below)
to collapse the balloon after landing
Aviation cadets average seven instruction rides each plus at least one ride in
which they are in complete charge. Each must be able to land his bag gently, a trick
that isn't as easy as it looks and that is accomplished by valving enough gas to
cause the balloon to drop, and then judiciously dropping sufficient ballast to ease
the fall and finally bringing the balloon almost to equilibrium as it approaches
the ground.
Learning how to ascend through a temperature inversion is easy but learning how
to descend through the same kind of freak condition and to do it safely is more
difficult. After a balloon has been forced up through cold air into a layer of warm
air it is just as reluctant to descend again as it was to make its initial climb.
The only way to get down is to valve enough gas to cause the balloon to fall
through. That is easy, then the pilot must immediately estimate the amount of ballast
that he must jettison to check the elevator-like descent and prevent a crash landing.
A free balloon is the most sensitive vehicle in which man ever rode. Not only
does it react to the slightest change in equilibrium, it responds to the faintest
breeze and to the slightest variation in temperature. If allowed to seek its own
altitudes during a low-level cross-country flight, a balloon would perform an erratic
series of ups and downs. The heat radiating from a plowed field would send it toward
the sky, but cool air above an adjacent orchard will cause it to descend again as
soon as it drifts over the trees. Heat waves from a concrete highway have a pronounced
effect and the balloon seemingly floats up and over an invisible hurdle when it
crosses such a highway. In time a balloon pilot acquires a feel of his vehicle that
helps him anticipate its movements and to control its course.
The cadets who graduate from Steelman's lighter-than-air cruises have a certain
confidence that they didn't possess before. "Anyone can fly an engine," they remark,
"but you need horse sense to be able to fly a free balloon."
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