Evening star. [volume] (Washington, D.C.) 1854-1972, 1941-03-12
Dispute Over Patent
Keeps Safety Device
From u. 5. Planes
Airliner Crockup Points
To Problem of Speed
On Tokeoffs, Landings
By JOSEPH s. FDGERTON

BY JOSEPH s. EDGERTON.
The Cincinnati airline crash, re-
sulting from skid on wet run
way after landing, is a reflection of
an increasingly serious problem in
the design and operation of large
military and commercial aircraft
particularly long range, heavily
loaded bombers-the reduction Of
take-of and landing speeds.
Solution of this problem by the
use of wing slots for the control o.
the flow of air over an airplane wing
at the critical stalling point, how.
ever, involves an international pat
ent controversy between the United
States and England. This COntro'
versy for many years has blocked
the use of slots in commercial anc
Army aircraft development in Amer
lea.
It is understood that a further
study of this controversy now is be-
ing made by the Justice Depart
ment. with a view to making posi-
BILE an increased development OF
wing slot and fan designs in Amer
lea to reduce landing and take-of1
speeds.
Becomes Military Problem.
War developments in Europe have
made the problem one of the most
critical facing designers. of military
aircraft today, in the opinion OF
American experts. Persistent bonn
bardment of major airports has
driven combat squadronS to smaller
and smaller airdromes and has ac-
centuated the already serious prob
lem of take-of and landing speed.
Preliminary investigation of the
Cincinnati accident indicates that
emergency use of brakes on a wet
runway while the airplane still was
rolling at high speed was the cause
of a skid which ended up against a
levee.
Among the most promising devices
for widening the performance range
of the modern airplane wing, or in
creasing the spread between max
imum flight speed and minimum
stalling or landing speed, are the
so-called "slots" and flaps" either
singly or in combination. One of
the early successful slots was de-
veloped by Handley-Page aircraft
engineers in England At the time
OF the Guggenheim safe airplane'
contest in this country, more than a
decade ago, the Curtiss AeronautiCal
Corp. acquired the right to use the
Handley-Page slot. The American
company also entered into an agree
ment with the English company for
commercial and military use of the
device in this country, under a 5 per
cent royalty clause which would
have involved up to 100000 in
royalties.
Z. S. Navy Works on Problem.
The United States Navy, in the
meantime, was conducting independ-
ent work on the slot problem and
1t. Col. Carl B. Harper. then on duty
here, developed combined slot and
flap with which he made many
experimental flights at the Anacostia
Naval Aair Station and elsewhere.
The National Advisory Committee
For Aeronautics for many years has
carried on an extensive program of
development Of slots, flaps and other
methods of controlling the flow of
air about airplane wings.
4 controversy over the Handley-
Page-Curtiss agreement threw the
whole patent matter into the courts
and the English concern won a
Judgment which brought CONNER
cial development of the slots to a
standstil and set back Army de-
velopment of the device.
Navy Refuses to Pay Royalties.
The Navy Department, however
fought the English stranglehold and
an opinion of the judge advocate
generals department held the Har-
per combined slot and flap to be
an original development and the
Navy Department refused to pay
royalties to the English concern
The Navy today is using the slot
and flap extensively for carrier air
planes. where reduction of landing
speeds is vital. Several hundred
Navy scout observation airplanes
now have slotted wings, which have
proved successful.
There are many engineers and
designers who believe that further
application must be made of this
or a similar type Of control mech
sr1isrn before there can be anv
further increases in speeds and
carrying capacities Of aircraft and
before operational hazards In air
transportation can be reduced to
a minimum. 1t was pointed out
that five of the six airline accidents
In the United States since last Au-
gust have occurred during landing,
or during approaches to airportt
and there is feeling that some
II not all Of them, might have beer
avoided had some method of re-
ducing landing and stalling speeds
been used.