Evening star., 1928-11-18
LIGHTNING MENACE
TOFLYERS STUDIED
Guggenheim Fund to Promote
Aviation Plans Research
Work.

the Promotion of AeronauticS in con-
neCtlon with Its efforts to eliminate the
element of hazard in commercial avia-
ton The study is IN line with the
organizations policies as demonstrated
in its fight against the fog danger, at
present one of the outstanding avia-
tion handicaps.
The study Is expected to reveal the
degree of danger encountered by the
aviator in flying through thunderstormS
and to determine what methods may be
adopted TO lessen the risk of planes
being struck by lightning or thrown out
Of control in the unusual atmospheric
conditions prevailing in electrical
storms.
The lightning studies will be con-
Quoted in connection with the fog COM"
bat work in special laboratory air.
plane now being prepared by the Gug-
genheim organization for use on test
section of regular airway.
With the safety Of the airplane
under proper conditions satisfactorily
established, we are now concerned with
the reliability of the airplane under adj
verse circumStances-in storm or in fog
or i'll any meteorological condition that
IS not normal" says Harry F. Guggen-
helm, president of the fund in bull
lotin announcing the undertaking of
the study AT its full-flight laboratory
over an established airway the fund
will begin this Fall the study of these
problems. drawing alike upon the eX-
perience of the past and the experiment
tation of today.
Tells of Factors.
IF there is much still to be discov-
cred about meteorological phenomena,
there is much that is already known.
The article IN this bulletin on the
hazard of lightning in aviation tells OF
some of the factors that have been
observed it will be followed by two
other papers discussing the hazard OF
thrnderstorms and the hazard of fog. y
The bulletin contains discussion
by Prof Alexander George McAdie
professor of meterology at Harvard
University and director of Blue Hill
Observatory and former official of the
Weather Bureau here, on the hazard
of lightning in aviation. In his article
rrof McAdie outlines experiments
made by scientists to determine the
causes and characteristics of lightning
since the days of Benjamin Franklin's
historic experiments with his kite and
key. He then goes into discussion OF
the energy Of the average lightning
flash and possible methods OF con-
trolling its destructive forces.
1T is especially necessary that in the
new field of aviation, where transporta-
ton is through the air, ard between
q charged cloud and an induced earth
charge, or between two charged clouds,
steps be taken to secure safety" Prot.
McAdie said.
mo argument is needed to convince
us of the value of the fullest possible
knowledge OF conditions under which
this tremendous electrical energy IS de-
veloped and dissipated Let US try to
calculate the energy of a moderate
streak of lightning. Various modiflca-
cations of the kite experiment have
been made at Blue Hill Observatory.
There have also been a number of
lightning strokes on kite wires at vari-
Gus Weather Bureau stations, and these
have been tabulated and described else
where
Let us consider a typical case. With
several large kites flying and about
600 meters of kite string (steel piano.
forte wire l MN. in diameter) out, a
thundercloud coming rapidly from the
West. there is a sudden streak of light
unGer the cloud. and GOO meters
1,9G3 fee) of the wire disappear, leav-
ing thin trail of smoke. incidentally
there are some lively, involuntary move
mcnts by the observers in the kite
house. bat fortunately no fatalities"
Prof. McAdie then goes into highly
technical discussion of the results of
his and similar kite tests, which he
says indicate that the energy of mod
crate lightning strokes range from a
few million to 100000000 volts.
1--WE shall never control lightning"
Prof, McAdie continues, until we
manage to slow down the discharge.
If the stroke could be delivered
gradually we might devise some means
to minimize the present destructive
effect. There are cases of 'corkscrew-
ing flashes and there may be some-
thing like a progressive breakdown
which later knowledge may be able to
utilize, but at present with most flashes
the effect is that due to large output
of power delivered in an extremely
short period, Peek's definition of light
ming rs an electrical explosion seems
TO us to fit the case. At present neither
plane nor airship is fitted to withstand
such a violent shock. development of
eat and likelihood of fire."
Double Danger Present.
In concluding his discussion Prof.
MoAdie says:
az t--dI picCeuSS emphasizes the
fact that as yet the airman should not
knowingly incur the danger incident to
the proximity of a highly-charged
cloud. There is a double danger-first,
from the lightning. and. second from
the existence of wind gusts, vertical as
well as horizontal, which make it very
difficult. if not impossible, for even
Skillful flyer to control his plane. The
catastrophe of the Shenandoah may
illustrate the latter danger, for it was
apparently not the lightning, but the
terrific up-and-down thrusts of the air
currents which brought disaster.
For the present it must suffice to
say that airmen should keep a viglant
lookout for cumulo-nimbus clouds
tthunderheadS) and steer course away
from or around them.
The probability of thunderstorms is
now indicated at all airports and in
time there will probably be installed
electrometric apparatus, whereby the
potential gradients can be determined
ana approximate electric field strengths
given. 1t will also be possible eventually
10 equip planes and ships with devices
that will automatically warn of the
approach of charged clouds and dam
gerous conditions. Until this is done
The wiseSt course is to avoid unnecessary
risk. Not every bad-looking cloud is
going to cascade its electrical and storm
energy into passing plane. but the
clements Of danger are there and
wise aviator will hesitate to take
chances"