3498 research outputs found
Sort by
The calculation of the wave drag of a family of low-drag axisymmetric nose shapes of fineness ratio 4.5 at zero incidence at supersonic speeds
No full textThe pressure drag coefficients of a particular family
of convex logarithmic projectile nose shapes in which the nose
angle is an important parameter have been calculated over a range
of supersonic Mach numbers using a rapid approximate method due
to Zienkiewicz.5
The optimum nose angle for minimum wave drag of these
profiles for each Mach number has been obtained. It is shown
that above N = 1.5„ approximately, the optimum shape is similar
to the hypersonic optimum profile and has the sane or- less wave
drag than this profile. However for values of M/F, where P
is the fineness ratio, below 0.5, both the hypersonic and the
logarithmic optimum profiles have a higher drag than the so-called
cubic profile (Ref, 9)
The wave drag of highly-swept wings: a comparison of linear theory and slender body theory
No full textThis note comments on the comparison between the
answer obtained by linear theory for the wave drag of
slender-wings (as interpreted by the limit and that value for the drag obtained by Slender-Body Theory.
It is shown that for fully tapered wings the agreement is
exact, and that there is reason to suppose that the same
is true for all wing planforms, unless the trailing-edge
is unswept, or the wing section has a finite trailing-edge
thickness. Some remarks are included concerning the drag
of slender delta wings
Notes on the theory of planar electric networks
No full textThe primary purpose of these notes is to
sketch an approach to the elementary algebraic
theory of planar electric networks which conduces
to a formal dual correspondence between the
so-called mesh and nodal representations of
planar networks that is complete in every respects
It is also shown that if general variables are
employed in the analysis of a network the number
of voltage or current equations that serve to
describe the network is infinite.
Finally, it is demonstrated that the impedance
or admittance matrix of a passive network is not
necessarily symmetrical
Plastic buckling of a plate in shear
No full textThis note derives the mathematical equations for
the analysis of the shear buckling of a plate, in the case where
the initial stresses exceed the elastic limit of the material.
It is hoped at a later stage to apply this theory to test
results, which are being obtained using rectangular torsion boxes
Pressure drop in "Velflo" pipe bends of one diameter throat radius: tests carried out by the College of Aeronautics for Wilmot Breeden Ltd
No full textThese tests were similar to those recorded in College of Aeronautics Note No.
95(2) by A. G. Smith, A. R. C. S. , B. Sc. , D. I. C. , and J. P. H. Webber, to which
the reader is referred.
This reo
port gives experimental data for the pressure drop in "Velflo" pipe
bends of 90 bend and one diameter throat radius. The bends were of 3" - 9"
nominal diameter and the range was covered in steps of 1". Pressure drop data
are provided in the form of pressure drop in the bends against nominal mean velocity
for air of density 0.0763 lb/cu. ft. By "nominal mean velocity" is meant the mean
velocity which would occur in a pipe of bore equal to the nominal for a given flow rate,
and by "pressure drop" is meant the additional drop in pressure which occurs when
a bend is inserted between two straight lengths. Both the bends and the pipes tested
varied slightly in bore from the nominal diameter. Also given in the report is the
non-dimensional form of the data, (useful in assessing consistency between the
different tests) and the form of pressure drop against volume flow rate. This latter
form is probably the most directly useful to customers of Wilmot Breeden Ltd
Some tests on a circular ground effect machine with forward speed
No full textWind tunnel tests have been made on a circular-wing with 90° downward
peripheral blowing both in and out of ground effect. Tests made with two slot widths,
a range of blowing pressures and choked jets, indicate that Cu is a unifying parameter
for this type of test. The windspeed was varied between 0 to 200 ft/sec. at zero
incidence and the static pressure distribution on both top and bottom surfaces was
measured. The sum of the integrated pressures on both upper and lower surfaces
3 agreed reasonably well with the measured overall lift. Flow visualisation on a
streamwise plate beneath the model showed the vortex system and the eventual
4 collapse of the forward jet with increasing windspeed
Grinding theory
No full textThis report presents a review and extension of current grinding theory. Grinding
operations are classified on the basis of (a) the cutting action of the grit, (b) the geometry
of wheel and work, (c) the type of chip produced, (d) the existence or otherwise of a
continuous lateral traverse of the wheel.
The theory is developed using the above method of classification. Recent experimental
work by Purcell(12) on the wear of the wheel in surface grinding is reinterpreted in the light
of the theory. It is shown to be consistent with the postulate of a constant task per grit.
A method of calculation is suggested by which a satisfactory surface grinding technique may
be applied to the form grinding of gears, where the task per grit is not independent of the
imposed grinding conditions
The effect of nitrogen in alpha-iron on ferromagnetic domain boundary movement examined by a mechanical damping method
No full textThe effect of ageing below 200°C on the hysteresis loss in
a-iron containing nitrogen has been investigated. The extent to
which nitrogen is removed from solid solution during ageing, and the
domain boundary hindrance developed, was assessed by mechanical
damping, using a low-frequency inverted torsional pendulum.
Nitrogen, both in solution and as the precipitated form Fe5N, was
found to increase the resistance to domain boundary movement, the
precipitated form being the more effective in this respect. Most
of the damping changes due to ageing are developed in less than 2
hours at 150°C; a further investigation to cover this region would
need to be undertaken to establish quantitative relationships
Characteristics of the high temperature mechanisms of creep and recovery in graphite
No full textThe research reported in this document has been made
possible through the support and sponsorship of the U.S.
Department of the Army, through its European Research
Office. This report, not necessarily in final form, is
intended only for the internal management use of the
contractor and the U.S. Department of the Army
Relationship between the limits of fit determined from B.S. 1916 and the functional requirements for interference fits
No full textIntroduction
When a designer wishes to choose a shaft and hole deviation and
tolerances, as, for example, an interference fit, he may be led to
assume, when reading B.S.1916, that a particular fit combination
will give the same functional characteristics over the entire size
range covered by the standard.
It is the intention of this note to show that this assumption is
not necessarily valid, and that the fit combination_ required to meet
a particular functional requirement will vary with size, These
comments are not intended as a criticsm of the standard as such but,
rather, that a supplement to the standard is required, to give the
designer guidance on the choice of fit for particular functional
requirements