Forty-Fourth Annual Report of the National Advisory Committee for Aeronautics Administrative Report Including Technical Reports Nos. 1342 to 1392 Page: 71 of 126
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OPERATING PROBLEMS
The daily operations of aircraft and missiles pre-
sent problems which require solution or alleviation for
purposes of safety, efficiency, and economy. Research
information is also needed by the designers and man-
ufacturers as well as the operators. For many years,
therefore, the NACA has studied various aspects of
aircraft operating problems such as atmospheric tur-
bulence, icing, ditching, aircraft and missile noise, crash
fire and survival, flight instrumentation, landing and
takeoff operations, and aircraft braking.
The NACA has been aided in its research activities
in the above areas by the deliberations of the Commit-
tee on Operating Problems, the Subcommittee on Me-
teorological Problems, the Subcommittee on Aircraft
Noise, the Subcommittee on Flight Safety, and, until
this year, the Subcommittee on Icing Problems. Dur-
ing this year NACA icing research has been limited
to writing reports on previous investigations and to
supervising the use of NACA icing research facilities
by non-NACA personnel who were testing aircraft
components under simulated icing conditions.
FLIGHT SAFETY
Flight safety research encompasses many problem
areas associated with the operation of aircraft. Haz-
ardous conditions may arise at any time from sources
such as the runway, the weather, the engines, the in-
struments, the controls, and the landing gear. NACA
investigations are thus aimed at specific problems to
obtain information useful to the manufacturer and the
aircraft crew in the industrywide effort to improve
safety.
Aircraft Instrumentation
The angle between the relative wind in the plane of
symmetry and the longitudinal axis of the airplane is
the angle of attack, and its measurement is an impor-
tant requirement for stall warning, cruise control, and
armament considerations. Three types of angle-of-
attack sensing devices have been tested in a wind tun-
nel and in flight to determine calibration and posi-
tion error data. One result showed that the best sensor
location for operation throughout the subsonic, tran-
sonic, and supersonic speed ranges is a position ahead
of the fuselage nose.
Accurate measurement of airspeed is necessary for
safe and efficient flight operations. An investigation
has been made to determine the external interference
effects of flow through the orifices of an airspeed headsuch as would occur due to instrument volume at high
rates of ascent or descent in flight. The results indi-
cated that the static-pressure error increased almost
linearly with increase in mass flow through the orifices.
A study has also been made on the accuracy with
which pressure altitude can be measured with current
systems. The analysis showed that the accuracy de-
pends on errors in the measuring systems, errors aris-
ing from operation of the system, and variation in at-
mospheric pressure. In another study a survey was
made of the errors associated with the measurement of
static pressure on aircraft. The errors considered were
associated with the static-pressure tube or fuselage vent
and the location of the sensor in the flow field of the
airplane.
Engine Reliability
Turbojet engines must either be repaired or replaced
after specified number of hours of operation. For rea-
sons of safety and economy, it is necessary to know
as accurately as possible when engine changes are to
be accomplished. An investigation has been made to ob-
tain information on the effect of overtemperature and
heat treatment on the life of turbine buckets. Results
indicated that overtemperatured buckets did not frac-
ture in abnormally short operating times. Cracking
was the principal mode of failure of buckets.
In another study a method was developed to help
decide whether jet-engine compressor blades that have
been nicked in service are safe from fatigue failure
with continued engine operation. These nicks are the
result of foreign objects being drawn into the air in-
let. A procedure has been worked out for making
limit charts that indicate whether a blade showing
damage should be accepted or rejected.
Aircraft Ditching
For years the NACA has conducted scale-model
ditching investigations of aircraft configurations to
furnish designers and operators with information on
ditching characteristics and behavior. Models of fight-
ers, bombers, and various types of transports have been
tested by utilizing a catapult and water tank system.
With the advent of turbojet aircraft, the need for addi-
tional ditching data on new configurations has been
met by recent tests. In addition, dithing aids such as
hydro-skis and hydrofoils attached to the aircraft fuse-
lage bottom have been under study to determine their
effectiveness in helping to make a water landing more
successful.
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Forty-Fourth Annual Report of the National Advisory Committee for Aeronautics Administrative Report Including Technical Reports Nos. 1342 to 1392, report, 1959; (https://digital.library.unt.edu/ark:/67531/metadc64173/m1/71/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.