Evening star., 1952-01-18
Anti-Aircruft Batteries
Outmoded in New War
Ground Defenses Seen Week
Against Hish-Speed Planes
By Thomos R. Henry

0N NStSuSSS SSSH VSON
Against High-Speed Planes
By Thomos R. Henry
Anti-aircraft batteries, brought to a
high stage Of effectiveness In the last
war so that they constituted the major
defense Of cities against bombers, prob
ably win be quite outmoded in any fu-
ture war between major powers.
This is revealed by physicists Of the
John Hopkins University Laboratory Of
Applied Physics where the major work
u being done on the development Of
guided missiles to stop air attacks.
Dr.. Ralph e. Gibson, director of the
laboratory, is quoted in q university
publication. Johns Hopkins Magazine:
We shall soon no longer have time
to think. We will have to base our de-
tense on versatile. automatic, high-speed
devices which we have endowed with
intelligence and power to act for us to
destroy the attackers, or strike sud.
den and paralyzing counter blow"
Weakness Of Ground Defenses.
A vivid example is given of the weak
ness OF any possible ground defenses.
suppose" the authoritative &C.
count Of the work states, "an enemy
plane is flying towards Philadelphia at
q speed Of 900 miles an hour, not an
excessively high speed in these DAYS.
Six hundred miles per hour is $50 feet
per second. Suppose that this plane is
being attacked by an anti-aircraft gun.
Inc average time Of fight of shells
from this gun to the target is, let us
imagine. Is seconds.
Between the moment the shell
leaves the gun and the time it arrives
at the point where it was aimed the
bomber will have travelled 13,20O feet.
two-and-a-half miles.
The shell, Of course, Is not aimed at
the bomber but at a point where it is
expected to be Is seconds after firing,
II. during those is seconds, the pilot has
changed his course by as little as a half
degree he will miss the anti-aircraft
shell by 106 feet. In order for the shell
and the bomber actually to collide the
pilot would have to fly his plane with an
accuracy Of one part in 10000.
Suppose that guns are available
which give the shell an average velocity
OF 5000 feet per second during the arbi-
trarily chosen flight time Of is seconds.
In Is seconds the shell would travel
$4,000 feet. But If the plane were fiyine
at an altitude Of 10000 feet 1t could be
only 10000 feet away from the gun Ion.
gitudinally for the shell to be able to
reach it. It would take the gun less than
13 seconds to cover that distance and to
appear directly above the anti-aircraft
gun itself.
But let us imagine that somehow
perhaps by adding propelling system
70 the anti-aircraft shells. by adding
wings to them, or by increasing the muz-
zle force Of the guns-we could increase
their range. Frankly that would not
enable US to do q whole lot.'
Would Have to Be superman.
But, DR.. Gibson continues. "it il
highly unlikely that any antt-afrcraft
gunner. unless he is some sort Of suner-
man as yet undiscovered in the armed
forces, can fire his gun 30 accuratalv
That he will Invariably hit his target ON
the nrst try. He will usually have to
shoot number Of rounds at the incon.
ing plane before he hits it. II the a,In.
ner fires round, then waits ton seconds
to observe his fire, then tlres aeain
what would happen?
Even If the plane were moving q.
slowly as 40 miles an hour an anti
aircraft gunner firing shells which trave,
at 6l5 miles an hour could get In onlv
three shots at the plane before Il ap-
peared over Philadelphia. # the shell
could be made to travel at the SUPER
sonic speed Of 1.640 miles an hour he
could take six shots at the attackin9
plane between the time 1t passed Atlantic
City or New Brunswick and the tims n
reached Philadelphia.
II Philadelphia Is to be resllv nro.
tected against this bombing attack ths
plane must be shot down, If the attack i.
coming from the north, at least as far
away as Trenton. With the supersonic
smell three rounds could reach the plane
But the plane may simply be making
1eint at Philadelphia. BY the time an
anti aircraft shell reaches point on the
predicted course to Philadelphia ths
plane may have veered south to Wash
1ngton or north to New York, completely
out OF the shells path. It seems rather
po1ntless to expend high-priced shells
on what probably would be the losing
side OF guessing game between the de-
lenders and an enemy pilot"