The Wilmington morning star., 1945-10-11
Tube Workers 7houqht
They Were MakingAids
ForDeafArny NauvMen
BY FRANK CAREY
,sociated Press Science Writer

WASHINGTON, Oct. lO-(RESe
secret was development of the
VT fuse that many of the work
ers producing the tiny vacuum
tnbes used in one of the world $
most deadly devices thought they
we're used in hearing aids for sol.
diers and sailors!
Production of those tubes was
so Notwithstanding a total
of more than 100000 in five
vears-that scientists in charge OF
the development said the workers
sometimes must have wondered
whv there was such tremendous
number of deaf officers and en-.
listed men in the armed services. !"
Other workers thought they were
making the tubes for radar sets.
Actually, of course, they were for
tinv radio sets built into the VT.
Reflected radio beams explode
shells. bombs or rockets when they
arrive within lethal distance Of
~
their target.
Because of the need of maintain
ing secrecy on the VT, plants max
ing tubes and other parts were not
given Army and Navy co awards.
Security officials wanted to divert
attention entirely from them.
Many workers thought theirs
was Just humdrum job, yet it
represented one of the toughest
and most dramatic-research and
development problems of the war.
Scientists of the National De-
Tense research committee began
research on the ''VT" at the re-
quest of the Navy in 1910. They
were faced with this problem:
How to produce a fuse tiny
enough to 60 into the nose of a
shell and yet rugged enough to
withstand the terrific shock of
being fired from a gun at an &C.
celeration 10000 times the force
of gravity, and the further shock
of spinning ATS times a second.
The scientists started out by
seeing how much punishment con-
ventional small-sized radio tubes
could take-tubes of the types used
in hearing aids.
They immersed tubes in led
blocks and took pot-shots at the
blocks with % rifles. They MINERS
ed tubes in wax and then dropped
them from the roof of a tall build
ing onto concrete driveways. They
shot tubes from big guns.
The results indicated that small
tubes, if made more rugged, would
probably do the trick.
Several industrial firms were
put to work. By spring of 1912,
large-scale production was start
ed.
1t was found that careful atten-
ton to glass quality and the elm
nation of strains permitted glass
tubes to successfully withstand
shooting from guns.
Moreover, the tubes were mount
ed in rubber caps which were then
imbedded in a wax compound.
Finally, the metal components of
the thumb-siZed tubes were de-
signed according to engineering
principles used in building bridges
and skyscrapers.
Utmost care required by the TO-
900 workers engaged in the pro-
duction, engineering and quality
control of the tubes. (More than
100000 workers were engaged in
all places of fuse production.)
Every tube was spun in a centri-
fuge to an acceleration of 10000
times the force of gravity after it
left the production line. Daily
samples were shot from a gun.
Here's an idea of the rate of
production:
In peacetime, the entire vacuum
tube production of the country was
100000 a day.
In June, 1915, the firm produc-
ing more than IS per cent of the
VT tubes was turning out 100000
day at % individual plants.
The most rugged tubes were used
in fuses designed for rotating PRO-
Jectlles-the kind used in most ar
tillery guns.
Easier requirements were made
Of tubes to be inserted in bombs
any types of rockets which do not
rotate in flight.
A falling bomb does not have
the initial velocity of gun-fired
prolectile. Neither does rocket,
but rugged tubes also were requir-
ed for spinner" rockets.