Evening star., 1922-07-02
HEZICOPIER TOO COSTLY
FOR COMMERCIAL USE
DR.: Zahm, Navy Expert, Declares Invention
Has War Value-More Danger
Gus Than Airplane.

The helcopter or vertical-ris:ng
air machine. is not an impossibility,
and should a real use for such a type
arise successful ones may be seen
before many years. according to DIR.
Albert F.. Zahm. aeronautical expert
FOR the Navy. Had there been a
need for the helicopter during the
war. he said. any of several types
could have been perfected. of which
working models have been flown.
DR.. Zahm is an expert on design
and construction of all manner OF
flying machines For years he has
applied his time to perfection CT the
a,rplane. and is well qualified 10
pass upon the >ca pa bilities of any
Much interest has been shown OF
late in reports Of successful machines
OF the helicopter type beng nerf""led
in both Germany and England. How
ever. while some flights have been
made. none of any consequence are
reported by machine equipped with
horizontal propellers or revolving planes
designed to rise vertically from Il con-
fired SPACE and descend on the same.
Extra Rush in Accidents.
That the helicopter is possible. DR.
Zahm said. is proved b. the German
machine. which. rising several times
tn moderate heights. has carried OBJ
servers. remained almost stationary
while in air and descended in safety
The machine. however. has made nc
extended fight. such as would prove
its depCnda tilitv. but WAS tethered
10 the ground bv a mocrir- rope. AT
times. when the motors failed. the
saved themselves orlv by ieapine
with parachutes.
The experiments are continuing
however, with the purpose of per-
fcctinE motor which can be de-
pended uDon to maintain the machine
without sudden failure. the scientist
explained. for. as soon as the engine
stops. the machine cannot glide to
the ground. as does an airpIane. but
drops vertically. In a proper descent
the propellers should be whired SLOWLY
TO ease tn" landing.
Present hopes of attaining successful
vertical flight rest mainly upon the en-
dea vors of Emile Berlirer. Washington
inventor. whose experiments with the
helicopter have extended over a long
time. and of Louis Brennan of London
whose newest machine is reported as
win the observation-disclosures prize Of
fered by the British air ministry fol
successful fight.
Best Types to Date.
The helicopters upon which most ex-
perimentat:on has been made consist
mainly of two or more propeller screws
mounted horizontally on a vertical
shaft, bearing engines. fuel and pass
engers Equal numbers of propeller
blades must revolve in opposite direc-
tons that the body Of the machine may
not spin like a top. The motors. tanks
and body have been mounted in various
positions. but the German machine has
a sort of pulpit car mounted at the tor
of the shaft over the propellers for the
operators.
Whether or not this type of machine
is brought TO actual use, DR. Zahm
stated at least two other types OF
planes that may fly vertically have beer
offered to the government. This fact is
not widely known.
One of these. of which DR.. Zahm OBJ
served experiments with a working
model was almost identical with the
present type of plane. except tina,
mounted behind the body We're two
sets of air vanes, in groups, tilted at ar
adjustable angle. like those of Venetian
blinds
When the power was turned on. he
said, the wash of the air stream from
the propellers. pushing against these
groups of vanes, caused the model to
rise gently vertically. The model was
held in midair by the action. and wher,
the power diminished it returned gently
TO earth. full-size machine Of the