Research abstracts

The footnote regarding classified documents on the unclassified
sections of Research Abstracts Kbs, 29 and 30 should be deleted. There
were no documents described therein that came within this category; this
note was inadvertently included.






































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National Advisory Committee For Aeronautics


Research Abstracts


NO.32


NOVEMBER 7, 1952


CURRENT NACA REPORTS

NACA Reut. 1062

INVESTIGATION OF WEAR AND FRICTION PROP-
ERTIES UNDER SLIDING CONDITIONS OF SOME
MATERIALS SUITABLE FOR CAGES OF ROLLING-
CONTACT BEARINGS. Robert L. Johnson, Max A.
Swikert and Edmond E. Bisson. 1952. ii, 12p
diagrs., photos., tab. (NACA Rept. 1062 Form-
erly TN 2384)

The wear and the friction of brass, bronze, beryl- -c
lium copper, monel, Nichrome V. 24S-T alummum,
nodular iron, and gray cast iron sliding against
hardened SAE 52100 steel were studied. ,
9 -j
NACA Rept. 1064 I

LUBRICATION AND COOLING STUDIES
CYLINDRICAL-ROLLER BEARINGS AT HIGl
SPEEDS. E. Fred Macks and Zolton N Nem th.
1952. li, 15p. diagrs., 2 tabs. (NACA Rept. 1064. -
Formerly TN 2420)

Oil inlet distribution (5 methods were investigated)
and oil inlet temperature (1000 to 2050 F) were
found to be significant factors in the cooling effec-
tiveness of a given quantity of oil. Dimensional
analysis was used to generalize the test-rig results
so that it is possible to predict the inner- or outer-
race temperatures above oil inlet temperature from
a single curve regardless of whether speed, load,
oil flow, oil inlet temperature, oil-jet diameter or
any combination of the parameters is varied.

NACA Rept. 1068

AUTOMATIC CONTROL SYSTEMS SATISFYING CER-
TAIN GENERAL CRITERIONS ON TRANSIENT BE-
HAVIOR. Aaron S. Boksenbom and Richard Hood.
1952. ii, 13p. diagrs. (NACA Rep. 1068. Form-
erly TN 2378)

An analytical method is presented for the design of
automatic controls that starts from certain arbitrary
criterions on the behavior of the controlled system
and gives those physically realizable equations that
the control system can follow in order to realize this
behavior. The criterions used are in the form of
certain time integrals. General results are shown
for systems of second order and of any number of
degrees of freedom. Detailed examples for several
cases in the control of a turbojet engine are present-
ed.


NACA TN 2779

EFFECTS OF MODERATE BIAXIAL STRETCH-
FORMING ON TENSILE AND CRAZING PROPERTIES
OF ACRYLIC PLASTIC GLAZING. B. M. Axilrod,
M. A Sherman, V. Cohen and I: Wolock, National
Bureau of Standards. October 1952. 42p. photos.,
diagrs.,. 4 tabs (NACA TN 2779)

Effects of approximately 50-percent biaxial stretch-
forming on the tensile and crazing properties of
polymethyl methacrylate were determined. Speci-
mens from formed and unformed pieces of the same
r'; sheets were subjected to standard tensile tests,
'*. C tress-solvent crazing with benzene, long-time ten-
a s\le loading, and accelerated weathering. Results
3 indicate that biaxial stretch-forming does not affect
thp tensile strength or modulus of elasticity but does
/ significantly increase the total elongation and strain
S and stress at the onset of crazing.


NACA TN 2781

THE EFFECTS OF DYNAMIC LATERAL STABILITY
AND CONTROL OF LARGE ARTIFICIAL VARIA-
TIONS IN THE ROTARY STABILITY DERIVATIVES.
Robert 0. Schade and James L. Hassell, Jr
October 1952. 56p. diagrs. photo 2 tabs.
(NACA TN 2781)

The results of an experimental and theoretical in-
vestigation of mthe effects of large artificial variations
of four rotary stability derivatives on the dynamic
lateral stability and control of a 450 sweptback-wing
airplane model are presented. The experimental
results are presented mainly in the form of flight
ratings for stability, control, and general flight be-
havior. Calculations of period and damping and of
the response to rolling and yawing disturbances are
also presented.


NACA TN 2799

SIMPLE GRAPHICAL SOLUTION OF HEAT TRANS-
FER AND EVAPORATION FROM SURFACE HEATED
TO PREVENT ICING. Vernon H. Gray. October
1952 19p. diagrs. (NACA TN 2799)

Equations expressing the heat transfer and evapora-
tion from wetted surfaces during ice prevention have
been simplified and regrouped to permit solutions by
simple graphical means. Working charts for quick
and accurate anti-icing calculations are also included.


*AVAILABLE ON LOAN ONLY.
ADDRESS REQUESTS FOR DOCUMENTS TO NACA, 1724 F ST., NW., WASHINGTON 2s, D. C.. CITING CODE NUMBER ABOVE EACH TITLE-
THE REPORT TITLE AND AUTHOR
6 z fy./ 0 -
uSor









2


NACA TN 2805

AN ENGINEERING METHOD FOR ESTIMATING
NOTCH-SIZE EFFECT IN FATIGUE TESTS ON
STEEL Paul Kuhn and Herbert F Hardrath.
October 1952. 35p. diagrs. 7 tabs. (NACA
TN 2805)

Neuoer's proposed method of calculating a practical
factor of stress concentration for parts containing
notches of arbitrary size depends on the knowledge
of a "new material constant" which can be established
only indirectly. In this paper, the new constant has
been evaluated for a large variety of steels from
fatigue tests reported in the literature, attention
being confined to stresses near the endurance limit;
reasonably satisfactory results were obtained with
the assumption that the constant depends only on the
tensile strength of the steel. Even in cases where
the notches were cracks of which only the depth was
known, reasonably satisfactory agreement was found
between calculated and experimental factors. It is
also shown that the material constant can be used in
an empirical formula to estimate the size effect on
unnotched specimens tested in bending fatigue.


NACA TN 2806

COMPARISON OF TWO- AND THREE-DIMENSIONAL
POTENTIAL-FLOW SOLUTIONS IN A ROTATING
IMPELLER PASSAGE. Gaylord 0. Ellis and John
D. Stanitz. October 1952. 61p diagrs. (NACA
TN 2806)

A solution is presented for inree-dimensional, in-
compressible, nonviscous, potential flow in a rotat-
ing impeller passage with zero through flow. The
solution is obtained for a conventional impeller with
straight blades but witn the inducer vanes removed
and the impeller blades extended upstream parallel
to the axis of the impeller. By superposition of so-
lutions two additional examples are obtained for dif-
ferent ratios of compressor flow rate to impeller Lip
speed. The three-dimensional solutions are com-
pared with corresponding two-dimensional solutions
and it is concluded that, at least for the type of im-
peller geometry investigated, two-dimensional solu-
tions can be combined to describe the three-
dimensional flow in rotating impellers with sufficient
accuracy for engineering analyses.


NACA TN 2811

ON THE CALCULATION OF FLOW ABOUT OBJECTS
TRAVELING AT HIGH SUPERSONIC SPEEDS
A. J. Eggers, Jr. October 1952 25p. diagrs.
(NACA TN 2811)

A procedure for calculating three-dimensional steady
and nonsteady supersonic flows with the method of
characteristics is developed and discussed An
approximate method is deduced from the character-
istics method and shown to be of practical value at
high supersonic speeds.


NACA
RESEARCH ABSTRACTS NO.32


NACA TN 2812


a._. I,


EFFECTS OF CYCLIC LOADING ON MECHANICAL
BEHAVIOR OF 24S-T4 AND 755-T6 ALUMINUM
ALLOYS AND SAE 4130 STEEL. C W MacGregor
and N Grossman Massachusetts Institute of
Technology. October 1952. 53p. diagrs., photos.,
4 tabs. (NACA TN 2812)

An investigation was conducted to determine the ef-
fects of cyclic loading on the mechanical behavior of
24S-T4 and 75S-T6 aluminum alloys and SAE 4130
steel. Specimens of the three materials were sub-
jectea to various numbers of prior fatigue cycles both
below and above the fatigue limits. Special slow-
bend tests were employed to show the effects of prior
cycles of fatigue stressing on the transition tempera-
ture to brittle fracture for SAE 4130 steel and on the
energy-absorption capacity of the aluminum alloys.
Micrographic studies were made to observe ana
measure crack formation and propagation and addi-
tional special tests were conducted to supplement the
results of the slow-bend tests. These included
Charpy impact tests, microhardness surveys,
tension tests, and fretting-corrosion studies.


NACA TN 2814

THE APPLICATION OF PLANING CHARACTER-
ISTICS TO THE CALCULATION OF THE WATER-
LANDING LOADS AND MOTIONS OF SEAPLANES
OF ARBITRARY CONSTANT CROSS SECTION.
Robert F. Smiley. November 1952. 37p. diagrs.
(NACA TN 2814)

The general equations governing the fixed-trim water
landing of a straight-keel seaplane of arbitrary con-
stant cross section are presented in such a form that
the landing motions and loads are expressed In terms
of the steady-planing characteristics of the seaplane.
In order to verify the general validity of these equa-
tions, solutions are made for the water landing of a
rectangular flat plate and are compared with experi-
mental impact data. Calculated and experimental
time histories of draft, velocity, and load are In good
agreement. A survey is made of the available infor-
mation on seaplane planing characteristics which is
suitable for use with the analysis of the paper.


NACA TN 2818

SECOND APPROXIMATION TO LAMINAR COM-
PRESSIBLE BOUNDARY LAYER ON FLAT PLATE
IN SLIP FLOW. Stephen H. Maslen. November
1952. 38p. diagr.. tab. (NACA TN 2818)

The first-order solution for the laminar compressi-
ble boundary-layer flow over a flat plate at constant
wall temperature is given. The effect of slip at the
wall as well as the interaction between the boundary-
layer flow and the outer stream flow is taken into
consideration. The solution is obtained explicitly in
terms of the known zero order, or continuum, solu-
tion. No assumptions regarding the Prandtl number
or viscosity-temperature law need be made. It is
found that the first-order solution gives a decrease in







NACA
RESEARCH ABSTRACTS NO.32


heat transfer and, for supersonic flow, an increase
in skin friction. For subsonic flow there is no first-
order shear effect. The change in heat transfer is
due to slip and the change in friction is due to the
interaction of the zero- and first-order velocities at
the outer edge of the boundary layer.


NACA RM 52109

A METER FOR TIMING THE FLOW OF VERY
SMALL VOLUMES OF A GAS. J. C. Westmoreland,
National Bureau of Standards. October 1952. 17p.
diagrs., photos. (NACA RM 52109)

A flowmeter has been developed which combines a
volume-time measurement of the flow, regulation of
the rate, and a determination or presetting of the
pressure head producing the flow. This meter is
capable of accurately metering and controlling very
small rates of gas flow within a closed system such
as those required in a small capillary tube.gas vis-
cosimeter.

NACA RM E52H26

EFFECT OF GEOMETRY ON SECONDARY FLOWS
IN BLADE ROWS. A. G. Hansen, G. R. Costello
and H. Z. Herzig. October 1952. 38p. pnotos.
(NACA RM E52H26)

The influence of blade-row geometry on secondary
flows in a two-dimensional cascade was investigated
qualitatively by varying independently the stagger
angle, aspect ratio, solianty, angle of attack, anu by
providing blade fillets. The influence of tip clear-
ance and relative motion between blades and wall
was also studied. Stagger angle and aspect ratio had
no appreciable effect on this secondary flow, whereas
solidity and angle of attack did affect the flow patterns
indicating the turning as a major parameter. Blade-
tip clearance induced a vortex produced by flow under
the blade enu which rotated opposite to the original
seconaary-flow passage vortex. The clearance vor-
tex displaced but did not reduce the secondary-flow
vortex When the wall was moved relative to the
blades, the blade leading surfaces "scraped" up
entrained fluid near the wall and Imparted a roll up
motion to the air in this region. On the tradiling
surface the fluid was pulled off the blade onto the
wall. The magnitude of the scraping effect was so
large that it masked completely the secondary-flow
and tip-clearance phenomena.

NACA TM 1351

ON THE DESIGN OF AIRFOILS IN WHICH THE
TRANSITION OF THE BOUNDARY LAYER IS
DELAYED. (Kyokaiso no Sen'i o okuraseru Yokugata
no tuite). Itiro Tani. October 1952. 74p. diagrs.,
8 tabs (NACA TM 1351. Trans. from Aeronautical
Research Institute, Tokyo Imperial Univ., Rept 250,
v. 19, no. 1, January 1943).

A method is presented for designing suitable thick-
ness distributions ana mean camber lines for airfoils
permitting extensive chordwise laminar flow. Wind
tunnel and flight tests confirming the existence of
laminar flow; possible maintenance of laminar flow


3


by area suction; and the effects of wind tunnel turbu-
lence and surface roughness on the promotion of
premature boundary-layer transition are discussed.
In addition, estimates of profile drag and scale effect
on maximum lift of the derived airfoils are made



BRITISH REPORTS


N-17215'

Aeronautical Research Council (Gt. Brit.)
TWO-DIMENSIONAL COMPRESSIBLE FLOW PAST
A SOLID BODY SYMMETRICALLY PLACED IN A
CHANNEL. P. V. Abdurahiman. 1952. 6p. (ARC
R & M 2443. Formerly ARC 11,243; FM 1205)

Goldstein and Lighthill have given a method of finding
the effect of compressibility on the potential flow
past a symmetrical body, either in unlimited fluid or
symmetrically placed in a channel, when the irrota-
tional incompressible flow is known. The object of
this paper is to use this method to find the effect of
compressibility on the velocity at the point C of an
oval placed symmetrically in a channel of breadth h.


N-17216

Aeronautical Research Council (Gt. Brit.)
NOTE ON SIR GEOFFREY TAYLOR'S CRITERION
FOR THE RATE OF BOUNDARY-LAYER SUCTION
AT A VELOCITY DISCONTINUITY. N. Gregory.
1952. 12p. diagrs., photo. (ARC R r M 2496. For-
merly ARC 10,630; Pert. 326; FM 1112)

Sir Geoffrey Taylor's criterion for the rate of
boundary-layer suction at a velocity discontinuity is
described, and is compared with experimental results
obtained from boundary-layer explorations. It is
found that, despite neglect of the pressure gradient
due to the curvature of the flow, the criterion gives
reasonable estimates of the suction quantity. On the
other hand, close agreement with velocity profiles is
only obtained when the pressure gradient is taken into
account.


N-17217l

Aeronautical Research Council (Gt. Brit.)
POSSIO'S SUBSONIC DERIVATIVE THEORY AND ITS
APPLICATION TO FLEXURAL-TORSIONAL WING
FLUTTER. PART I. POSSIO'S DERIVATIVE
THEORY FOR AN INFINITE AEROFOIL MOVING AT
SUBSONIC SPEEDS. R. A. Frazer. PART 11. IN-
FLUENCE OF COMPRESSIBILITY ON THE
FLEXURAL-TORSIONAL FLUTTER OF A TAPERED
CANTILEVER WING MOVING AT SUBSONIC SPEED.
R. A. Frazer and Sylvia W. Skan. 1951. 22p. diagrs.,
5 tabs. (ARC R 5 M 2553. Formerly ARC 4932;
ARC 0.205; ARC 5916; ARC 0.274)

The derivative theory due to C. Possio for an infinite
airfoil moving at subsonic speeds is reviewed, and
certain modifications are proposed. Derivative
values are calculated for a Mach number of 0.7 and
for values of the frequency parameter A ranging
from 0 to 5.0. For A < I the derivative values
based on a three-point collocation method are in fair








4

agreement with those given by Possto. For the range
1.0 < A < 2.0 five-point collocation is necessary,
while for A = 5.0 even seven-point collocation may
prove unsatisfactory. The numerical results obtained
are applied in Part II to estimate the influence of
compressibility and flying height on the critical speed
for flutter of a tapered cantilever wing.


N-17218*

Aeronautical Research Council (Gt. Brit.)
BOUNDARY-LAYER AND WAKE INVESTIGATION
IN SUPERSONIC FLOW. J. Lukasiewicz and J. K.
Royle. 1952. 22p. diagrs., photos., 2 tabs. (ARC
R& M 2613, ARC 12,130. Formerly RAE Aero
2292; SD 31)

The report describes the results of traverses of the
boundary layer and wake encountered in a small
supersonic tunnel at a Mach number of 2.5. The
tunnel was arranged with two throats in parallel
formed by two shaped walls enclosing a shaped
central element. Both the laminar and turbulent
boundary layers were encountered and compared
with existing experimental and theoretical results.
The frictional drag of the central element as deduced
from the wake traverses is in close agreement with
that calculated from considerations of laminar
boundary-layer growth over the surface of the ele-
ment. The tests also provide information relating to
the design of nozzle profiles, particularly at the
point of inflexion, where the changes of pressure
gradient may have a serious effect on the boundary
layer and on the velocity distribution.

N-17219*

Aeronautical Research Council (Gt. Brit.)
THE NUMERICAL METHOD OF CHARACTERISTICS
FOR HYPERBOLIC PROBLEMS IN THREE INDE-
PENDENT VARIABLES. C. K. Thornhill. 1952. 13p.
diagrs. (ARC R & M 2615; ARC 11,767. Formerly
Armament Research Establishment Rept. 29 48;
Theoretical Research Rept. 4/48)

Recent advances in electronic computing devices
suggest that it may soon be feasible to attempt nu-
merical solutions of problems involving three inde-
pendent variables. In this paper, preliminary con-
sideration is given to the extension of the numerical
method of characteristics for hyperbolic equations to
the case of three independent variables. A general
quasi-linear second-order partial differential equa-
tion in three variables is first considered, and the
characteristic surfaces and curves are derived,
together with the differential relations which hold
along them. It is shown that numerical integration
should be possible along the faces or edges of a
hexahedral grid. The equations are developed in
more detail for two special cases of compressible
flow, namely steady isentropic supersonic flow in
three-dimensional space, and unsteady flow in two
dimensions.

N-17227*

Aeronautical Research Council (Gt. Brit.)
TESTS ON A 'GLAUERT' NOSE-SUCTION AERO-
FOIL IN THE N.P.L. 4-FT. NO. 2 WIND TUNNEL.
F.. Cheers and Ola Douglas. 1952. 5p. diagrs.
(ARC R & M 2356. Formerly ARC 10,507; FM 1096;
Perf. 302)


NACA
RESEARCH ABSTRACTS NO.32

Tests on an 8.65-percent-thick nose-suction airfoil
designed by Glauert have been made in the-loot
No. 2 wind tunnel at the National Physical Laora-
tory at Reynolds numbers 0.385 and 0.577 x 106. The
results show that the section stalls at a lift coeffi-
cient of 1.13 without suction. With suction quantities
of 0.003, 0.0045, 0.006, and (with a wider slot) 0.012,
the values of CLmax were respectively 1.32, 1.34,
max
1.36, and 1.57.


N-17228*

Aeronautical Research Council (Gt. Brit.)
THE FLOW IN AN AXIALLY-SYMMETRIC SUPER-
SONIC JET FROM A NEARLY-SONIC ORIFICE INTO
A VACUUM. P. L. Owen and C. K. Thornhill. 1952.
8p. diagrs. (ARC R b M 2616; ARC 11,768.
Formerly Armament Research Establishment Rept.
30, 48; Theoretical Research Rept. 5 48)

The numerical method of characteristics is used to
calculate the flow in a steady supersonic jet of air
issuing from a slightly supersonic circular orifice
into a vacuum. The calculations are entirely numer-
ical, and no recourse is made to graphical methods.
The characteristic equations for steady supersonic
flow with rotational symmetry are first derived, and
then special consideration is given to the flow near
the axis of symmetry, where the normal step-by-step
numerical process breaks down. In the calculation,
the Mach angle in the plane of the orifice is taken as
850 to obviate the difficulties of a sonic orifice at
which the initial characteristics would be perpendic-
ular to the flow, and the potential equation parabolic.
The results should be practically the same as for a
sonic orifice. An alternative method of dealing with
a sonic boundary plane would have been the use of
analytical solutions for the initial flow in this region
The results of the calculations are presented in
diagrams. The solution is a universal solution
insofar that it applies to any similar jet, flowing
into any external pressure, in that region bounded by
the orifice and the first wave front which registers
the existence of an external pressure outside the jet
This fact allows the calculated pressure distribution
along the axis of symmetry to be compared with
experimental measurements in air jets with finite
pressure ratios, and good agreement is obtained.


N-17229*

Aeronautical Research Council (Gt. Brit.)
PRESSURE DISTRIBUTIONS AT HIGH SPEED ON
EC 1250 (DATA REPORT). J. A. Beavan and G. A.
M. Hyde. 1952. 12p. diagrs. (ARC R & M 2625.
Formerly ARC 10,729; Perf. 331; FM 1132)

This report puts on record, as data, pressure distri-
butions measured on a 5-in. chord airfoil of EC 1250
section in the 20- by 8-inch rectangular high-speed
tunnel at the National Physical Laboratory.






NACA
RESEARCH ABSTRACTS NO.32


N-17230*

Aeronautical Research Council (Gt. Brit.)
FOUR- AND EIGHT-CHANNEL DESYNN GRAPHICAL
RECORDERS. F. R. J. Spearman. 1952. 6p. photos.
(ARC R& M 2636; ARC 11,495. Formerly RAE Tech.
Note Instn. 119)

A four-channel recorder, providing continuous traces
against time on photographic film, has been developed
for use with any instruments embodying Desynn
transmitters. It is suitable for the measurement of
quantities which vary with a maximum frequency of
3 cps. It is made from F.24 camera component
parts, and uses the standard magazine and 5-In. wide
film. It has been successfully used for flight trials,
manufacturing drawings are available. An eight-
channel version, of which two or three may be
coupled together, is under development.

N-17231

Aeronautical Research Council (Gt. Brit.)
A THEORETICAL INVESTIGATION INTO THE
LATERAL STABILITY OF AN AEROPLANE CON-
TROLLED BY AN AUTOMATIC PILOT, WITH
PARTICULAR REFERENCE TO THE EFFECT OF
FLIGHT PATH ANGLE. T. W. Prescott. 1952. lip.
diagrs. (ARC R & M 2640; ARC 11.409. Formerly
RAE Tech. Note LAP 974)

Several autopilots produce aileron deflection propor-
tional to the movement between the airplane and the
outer gimbal of a vertical gyroscope. In nonlevel
flight, this relative movement is not equal to the
rotation of the airplane about its x-axis, and it was
desirable to investigate the lateral stability for steep
angles of climb and dive. Calculations show that
instability does occur, but that stability can be
restored either by making the rudder deflection
dependent on aileron movement in order to counter-
act the aileron drag coefficient, or by adding a rate
of yaw term to the rudder circuit. The addition of
both aileron and rate terms to the rudder circuit is
greatly superior to the addition of either term alone.
The aileron drag coefficient can also have a detri-
mental effect at the start of an automatic turn, and
response curves during entry into the turn have been
calculated for various degrees of aileron drag com-
pensation. The bank angle and sideslip response
curves are unaffected by the compensation. The rate
of turn response is Improved during the first second
but subsequently is little affected by aileron drag
compensation.


N-17232*

Aeronautical Research Council (Gi. Brit.)
ON A THEORY OF SANDWICH CONSTRUCTION.
W. S. Hemp. 1952. 9p. (ARC R & M 2672.
ARC 11, 568. Formerly College of Aeronautics,
Cranfield Rept. 15)

The theory of sandwich construction developed in
this paper proceeds from the simple assumption
that the filling has only transverse direct and shear
stiffnesses, corresponding to its function require-
ments. This supposition permits integration of the
equilibrium equations for the filling. The resulting
integrals are used to study the compression buckling


5


of a flat sandwich plate. The formulas obtained are
complex, but may be simplified in practical cases.
A second approach to sandwich problems is made in
section 5, where a theory of "bending" of plates is
outlined. This generalizes the usual theory, making
allowance for flexibility in shear This approach is
applied to over-all compression buckling of a plate
and agreement with the previous calculations is
found. This suggests the possibility of calculating
buckling loads for curved sandwich shells. A sim-
ple example, the symmetrical buckling of a circular
cylinder in compression, is worked out. The theory
developed would seem applicable to all cases of
buckling of not too short a wave length.

N-17233'

Aeronautical Research Council (Gt. Brit.)
SERVICE FAILURES IN AIRCRAFT STRUCTURES
ASSOCIATED WITH FATIGUE, REPEATED OR
DYNAMIC LOADS. J. B. B. Owen. 1952. 13p.
diagrs., photos. (ARC R & M 2688; ARC 9426.
Formerly RAE SME 3384)

This note gives examples and photographs of several
structural defects which have occurred in service
and shows that, although many failures may be due to
fatigue or the application of excessive static loads,
some are probably influenced by the repeated applica-
tion of loads of high intensity, and by loads of a
dynamic character. It is suggested that changes in
design aimed at (1) eliminating the loads causing
failure, for example, reducing in one case tab back-
lash, and (2) alleviating stress concentrations are
ways of reducing the incidence of defects due to
repeated loading.


N-17535*

Aeronautical Research Council (Gt. Brit.)
NOTES ON HELICOPTER ROTOR BEHAVIOUR
AFTER ENGINE FAILURE IN HOVERING FLIGHT.
W. Stewart and G. J. Sisslngh. 1952. 6p. diagrs.
(ARC R& M 2659; ARC 12,525. Formerly RAE
Tech. Note Aero 1997)

Calculations have been made of the changes in rotor
speed following engine failure on a typical helicopter
in hovering flight. Various time functions for the
collective pitch operation are considered. The re-
sults are in excellent agreement with the one
recorded case of an actual power failure In hovering
flight. Rapid pilot action in reducing the collective
pitch after engine failure is essential to prevent
dangerously low rotational speed of the blades. The
possibilities of automatic pitch reduction or of a
power failure warning to the pilot are considered.


N-17536*

Aeronautical Research Council (Gt. Brit.)
NOTE ON THE APPLICATION OF THWAITES'
NUMERICAL METHOD FOR THE DESIGN OF CAM-
BERED AEROFOILS. A. R. Curtis. 1952. 13p.
6 tabs. (ARC R & M 2665. Formerly ARC 12,154;
FM 1336; Pert.531)

Some minor developments in the technique of
Thwaites' numerical method of airfoil design are







6


described. In particular, the process of obtaining
the camber-line ordinates from the Goldstein
approximation I velocity distribution is discussed in
detail, the relevant tables of constants are given. An
opportunity is taken to include a complete set of 20-
point tables of conjugation factors needed in any
actual application of the numerical methods. The
theory underlying these tables is given by Watson in
R & M 2716.


N-17537*

Aeronautical Research Council (Gt. Brit.I
A THEORETICAL EXAMINATION OF THE EFFECT
OF DEADRISE ON WETTED AREA AND
ASSOCIATED MASS IN SEAPLANE-WATER
IMPACTS. R. J. Monaghan. 1952. 16p. diagrs.
(ARC R & M 2681; ARC 12,395. Formerly RAE
Tech. Note Aero 1989)

A theoretical examination is made of the dead rise
effect on associated mass and wetted area in the two-
dimensional impact case (vertical drop of an infinite-
ly long wedge at zero attitude). Available estimates
are summarized and a new theoretical formula is
developed by means of an expanding prism flow which
gives results for associated mass in very close
agreement with those given by Wagner's semi-
empirical formula (on which most of the estimates of
three-dimensional associated mass have so far been
based). In addition, the new treatment gives a formu-
la for wetted area which is not available from
Wagner's treatment except for very small values of
dead rise angle. Comparison is made between these
and other formulas in the light both of theory and
experiment and a brief survey is made of the assump-
tions involved in applying associated mass methods
to motions through a free surface.



N-17538*

Aeronautical Research Council (Gt. Brit.)
SYSTEMATIC WIND-TUNNEL TESTS WITH SLATS
ON A 10 PER CENT THICK SYMMETRICAL WING
SECTION (EQ 1040 PROFILE). G. F. Moss. 1952.
22p. diagrs., 6 tabs. (ARC R & M 2705; ARC 12,068.
Formerly RAE Aero 2294)

It was thought that present rules for the design of
Handley Page slats might be inadequate for modern
high-speed airfoil sections. These tests were made
on the EQ 1040 wing section to determine the optimum
slat setting for this type of wing profile. Three slats
were tested whose chords were 10 percent, 20 per-
cent, and 30 percent of the wing chord, over a wide
range of positions. Lift coefficients were measured
over the stall in each case. Some tests were made
with a split flap. Best results for the 10-percent
chord slat are obtained with very small gap and large
dip. Zero gap, that is, using the slat as a nose flap,
may in fact give the optimum. Optimum positions for
the larger chord slats are more conventional, but
require larger forward extensions than are given by
the old rules.


NACA
RESEARCH ABSTRACTS NO.32


N-17539"

Aeronautical Research Council (Gt. Brit.) .. -
NOTE ON SEMI-EXPERIMENTAL METHODS FOR
THE DETERMINATION OF AERODYNAMIC DERIVA-
TIVES FOR AN OSCILLATING WING-AILERON
SYSTEM. P. F. Jordan. 1952. 6p. diagrs., tab.
(ARC R M 2706; ARC 12,042. Formerly RAE Tech.
Note Structures 28)

A brief survey is given of existing semiexperimental
methods for the determination of two-dimensional
aerodynamic derivatives for unsteady motion of a
wing-aileron system (and, in particular, for aero-
dynamically balanced controls); a comparison with
(partly unpublished) experimental data is made. The
result is encouraging for further investigations.


N -17540'

Aeronautical Research Council (Gt. Brit.)
TESTS ON A MODEL BODY-WING COMBINATION
AT SUPERSONIC SPEED. P. J. Wingham. 1951.
4p. diagrs. (ARC R i M 2711. Formerly ARC
8229; Ae. 2663; FM 759)

The tests described in this report were made in the
1 -foot circular tunnel at the National Physical Lab-
oratory at a Mach number of about 1.4. The main
object was to determine the lift obtainable from
wings of very short span and in particular to see
whether the lilt curve departed much from a straight
line at incidences up to about 120, it being already
known that the lilt curve for a two-dimensional air-
foil was sensibly straight up to 200 or so of inci-
dence. Unfortunately it was not possible to measure
the drag load, so that only normal-force and pitching-
moment values are available.


N-17541'

Aeronautical Research Council (Gt. Brit.)
A METHOD FOR DETERMINING THE WATER STA-
BILITY OF A SEAPLANE IN TAKE-OFF AND
LANDING. H. G. White and A. G. Smith. 1952. 17p.
diagrs. (ARC R M 2719; ARC 6834. Formerly
MAEE Rept. H Res 163)

A direct method of determining the water stability in
take-off and landing of full-scale seaplanes is de-
scribed. The customary method of measuring full-
scale stability is by steady runs over a range of
speed and attitudes. This is tedious; it does not give
the true take-off stability and does not give the land-
ing stability. The steady-run stability is assumed to
correspond very closely to the take-off stability but
was originally used to obtain full-scale conditions
comparable with model scale. This report gives a
method of analysis of take-oil records of attitude
against speed, and results obtained by this method are
compared with the steady-run results. Results on the
Scion fitted with a I 2-scale Sunderland hull and Saro
with a 1 2.75-scale Shetland hull are used to establish
the method, but it has also been checked against the
available date on the full -scale Seal and Sunderland 1.
The take-off stability limits show remarkable agree-
ment with the corresponding steady run limits (to
within I 20) of the Scion and Saro. Evidence on the
Seal and Sunderland is insufficient for a definite con-
clusion in these cases, but there is no disagreement








NACA
RESEARCH ABSTRACTS NO.32


between the results obtained. The method is accurate
and quick to use, but takes no account of the ampli-
tude of porpoising so that a few steady runs would
still be necessary to establish this where required.
By use of this method, the investigation of the sta-
bility characteristics of a seaplane under different
conditions of weight, c.g., and flap angle can proceed
quickly on the evidence of about eight take-off records
at each condition, these records covering the full
attitude range. The method may also be applied to
find landing stability from landing records.


N-17542'

Aeronautical Research Council (Gt. Brit.)
THE HULL LAUNCHING TANK (DESCRIPTIVE).
A. G. Smith, G. C. Abel and W. Morris. 1952. 22p.
diagrs., photos. (ARC R& M 2723; ARC 6804.
Formerly MAEE Rept.H Res 161)

The hull launching tank has been built in order that
systematic measurements of impact pressures can
be made on large model seaplane hulls to supple-
ment full-scale tests, and to cover conditions of im-
pact which would be dangerous full scale. The ob-
ject is to obtain generalized formulas for the maxi-
mum local pressures, the total impact load, and the
simultaneous distribution of pressure on any hull
form for any impact condition. The report describes
the hull launching tank and apparatus, the range of
impact conditions possible for test, and the methods
developed for measuring the parameters which affect
the Impact loads. Theoretical considerations, the
results of tests and further developments, will be
found in existing or in subsequent reports.

N-17543'

Aeronautical Research Council (Gt. Brit.)
SOME ELECTRICAL INTEGRATING CIRCUITS AND
THEIR USE IN THE MEASUREMENT OF LOW FRE-
QUENCY VIBRATION AMPLITUDES. G. R.
Richards. 1952. 18p. diagrs. (ARC R & M 2724;
ARC 11,639. Formerly RAE Tech.Note lnstn.121)

The note investigates the possibility of making low
frequency vibration measurements by the use of
electronic acceleration measuring equipment in con-
junction with electrical doubly integrating circuits.
It is shown that by this method many of the disadvan-
tages associated with the use of seismic displacement
units can be obviated particularly over the frequency
range 2 to 40 cps. Three electrical integrating
methods are discussed, the correct circuit conditions
for the integration of periodic sinusoidal, rectangular
and triangular waveforms are derived. A descrip-
tion is given of an existing acceleration measuring
equipment incorporating two of the described inte-
gration networks; its sensitivity, frequency response,
and methods of increasing these factors are dis-
cussed in detail.


N-17544'

Aeronautical Research Council (Gt. Brit.)
AN EXPERIMENTAL INVESTIGATION OF THE
FLOW THROUGH A HELICOPTER ROTOR IN FOR-
WARD FLIGHT. P. Brotherhood and W. Stewart.
1952. 12p. diagrs., photos. (ARC R & M 2734; ARC
12,894. Formerly RAE Aero 2330)


7


Experiments have been made to determine the flow
conditions through a helicopter rotor in forward flight
using the smoke filament technique. This method
consisted of flying the helicopter behind an aircraft
from which smoke generators were suspended on a
long wire. The smoke trails passed through the main
rotor of the helicopter, and photographs were taken
from another aircraft in a side position. Flow condi-
tions at the rotor disk over a narrow bend on the side
of the advancing blade were investigated in this way.
The range of speeds covered was from 44 mph to
60 mph corresponding to a range of tip speed ratios
0.138 to 0.188. An increase in induced velocity from
front to rear of the rotor disk was obtained. The re-
sults are in reasonable agreement with theoretical
predictions.


N-17545'

Aeronautical Research Council (Gt. Brit.)
EFFECT OF RATE AND DURATION OF LOADING
ON THE STRENGTH OF AIRCRAFT STRUCTURES.
K. D. Raithby. 1952. 13p. photos., diagrs., 5 tabs.
(ARC R !i M 2736; ARC 12,600. Formerly RAE
Structures 39)

The effects of rate and duration of loading on the
structural strength of aircraft have been investigated
by comparing the failing loads of both wooden and
metal tail planes when tested at different rates of
loading, the duration of test varying from about
6 seconds to 3-3 4 hours. With wooden structures,
differences in strength due to rate of loading were
much less than those predicted from the results of
American tests on wood. With metal structures,
neither rate of loading nor sustained high loading had
any appreciable effect on the failing load.


N-17546*

Aeronautical Research Council (Gt. Brit.)
A DISTANT READING MANOMETER WITH PAR-
TICULAR APPLICATION TO THE MEASUREMENT
OF SMALL PRESSURES. A S. Halliday and
H. Deacon. 1952. 5p. diagrs., photos. (ARC
R & M 2744. Formerly ARC 11, 566; TP 247;
S & C 2227; Perf. 457)

The function of the manometer Is to enable small
pressure differences to be measured at a distance.
The instrument will measure either the difference
of two pressures or a single pressure relative to
atmosphere.



N-17547'

Aeronautical Research Council (Gt. Brit.)
FORCED FLOW AGAINST A ROTATING DISC. D.
M. Hannah. 1952. 17p. diagrs., 7 tabs. (ARC R & M
2772. Formerly ARC 10,482; FM 1088)

The steady motion of an incompressible viscous fluid
due to an infinite rotating plane lamina has been con-
sidered by von Karman and by Cochran; the motion
of fluid flowing with axial symmetry towards an infi-
nite stationary plane lamina has been dealt with by
Homann. The present paper deals with the general





UNIVERSITY OF FLORIDA


3 12 0 153 255 7


question of steady irrotational flow with axial symme-
try against an infinite rotating lamina, of which the
above are two special cases.


N-17587'

National Gas Turbine Establishment (Gt. Brit.)
THE FOULING OF TURBINE BLADING BY THE
PRODUCTS OF COMBUSTION OF PULVERISED
FUEL. PART I. THE DESIGN AND DEVELOPMENT
OF THE COMBUSTION SYSTEM. R. I. Hodge. June
1952. 35p. diagrs, photos. (NGTE Memo. M.154)

This memorandum describes the construction of the
pulverized fuel combustion chamber and the ancil-
lary equipment at present installed at the National
Gas Turbine Establishment, Whetstone, to conduct
an investigation into the effect on blading of the
operation of an open cycle turbine fired with pulver-
ized fuel. The developments found necessary to
give effective flame stability in this particular com-
bination of precombustlon and balanced vortex
chambers are set forth. Both the conditions assumed
in the design and those calculated to be obtaining at
what was subsequently found to be the point of opti-
mum operation (based on combustion efficiency) are
given. The analysis of the state of the exhaust prod-
ucts given at the end of this note is not complete but
p *ovides some idea of the basic medium of the blade-
fouling test conditions.


N-17657'

Forest Products Research Lab. (Gt. Brit.)
REVISED MANUAL FOR CONDUCTING TRIALS OF
TIMBERS FOR PLYWOOD MANUFACTURE.
R. A. G. Knight. June 1952. 11, 14p. (Forest
Products Research Lab. PRP 8. 1)

The Composite Wood Section of the Forest Products
Research Laboratory is completely equipped with
machinery and plant for the manufacture of plywood
of all types. The peeler will take billets up to 5 ft
6 in. long and 4 ft 6 in. diameter and the press will
make boards up to 5 ft square. With equipment of
this scale, an appraisal can be made of the value of
a timber for plywood manufacture, and problems at
any stage of the process can be investigated under
conditions comparable with those in commercial
factories but distinct from them in that the needs
of continuous production are absent. These investi-
gations are made to a prescribed plan so as to apply
uniform standards to all timbers, and the results
are issued by the Laboratory as Progress Reports in
the series "Trials of Timbers-for Plywood Manu-
facture.' The plan was originally prepared in collab-
oration with the Plywood Research Panel, and cir-
culated as Paper P. R. P. 5, 1, "Manual for Conduct -
ing Trials of Timbers for Plywood Manufacture" in
August 1950. After experience with the Manual in
tests on 26 species, the Panel saw that improve-
ments could be made that would simplify the work
and increase the practical value of the data obtained,
so the present Revised Manual was then compiled.
The original Paper P. R. P. 5, 1 is applicable to re-
porti up to No. 15, but for No. 16 and onwards, the
methods of P. R P. 8 1 apply. The changes are not
such as to nullify comparison between the earlier and
later reports.


NACA
i RESEARCH ABSTRACTS NO.3S


N-17722*


Royal Aircraft Establishment (Gt. Brit.)
HEAT TRANSFER AND PRESSURE LOSSES IN
COOLING DUCTS OF GENERATORS. Mary D.
Wright. June 1952. 17p. diagrs., 3 tabs. (RAE
Tech.Note EL.39)

In connection with the cooling of aircraft generators
an investigation has recently been made to determine
the pressure drop and heat transfer in the cooling
channels of an armature. In this note an attempt
has been made to correlate the results with theoret-
ical and established empirical relationships. The
description of the apparatus and experimental tech-
niques which were used will be described in a later
report.


N-177231

Ministry of Supply (Gt. Brit.)
DEVELOPMENT OF A PRE-STALL DETECTOR
FOR AIRCRAFT. R. T. Youngman. July 1952.
7p. diagre. (MOSS & TM 6/52)

This report describes a stall warning detector which
has been developed by the Ministry of Supply. It
depends for its operation upon the pressure changes
which occur on the undersurface of a wing. At cer-
tain points, the pressure increases at a fairly con-
stant rate with increase in angle of Incidence. A
detector which operates on this principle has the
advantage that there are no external parts.

N-17726*

Royal Aircraft Establishment (Gt. Brit.)
FATIGUE PROPERTIES AT LOW TEMPERATURE
ON TRANSVERSE AND LONGITUDINAL NOTCHED
SPECIMENS OF D. T.D. 363A ALUMINIUM ALLOY.
N. J. F. Gunn. June 1952. 23p. diagrs., photo.,
11 labs. (RAE Tech. Note Met. 163)

Tests have been made to ascertain the effect of a
specified subnormal temperature (-400 C) on the
notched and unnotched fatigue strength of the materi-
al. The test pieces were machined from a 5-inch
diameter, extruded D. T. D. 363A bar so that their
axes coincided with.the longitudinal and transverse
directions of the parent bar. The results of the
tests showed that some increase in fatigue strength
Is evident at -400 C for longitudinal specimens but
no appreciable change for transverse specimens Is
apparent.


MISCELLANEOUS


NACA ARR L4F26

Errata No. 1 on "DESIGN OF POWER-PLANT
INSTALLATIONS PRESSURE-LOSS CHARACTER-
ISTICS OF DUCT COMPONENTS". John R. Henry.
June 1944.


NACA-Langley 11-7-52 4000

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