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Bound and trailing vortices in the linearised theory of supersonic flow, and the downwash in the wake of a delta wing
No full textThe field of flow round a flat aerofoil at incidence can/may be regarded in linearised theory as the result of both bound and trailing vortices for supersonic as well as for low speed flight. This leads to a convenient method, given the lift distribution over an aerofoil, for calculating the flow round it at supersonic speeds.
As an application of the results the downwash is calculated in the wake of a delta wing lying within the Mach cone emanating from its apex. The downwash is found to be least just aft the trailing edge and is everywhere less that the downflow at the aerofoil. It increases steadily to a limiting value which is attained virtually within two chord lengths of the trailing edge. The ratio of the downwash at any point in the wake to the downflow at the aerofoil decreases with increasing Mach number and apex angle
Some related oscillation problems
No full textTwo simple means for establishing a relation between a pair of oscillation problems are briefly discussed. In the first, the displacements are connected by use of a differential operator. The set of natural frequencies is identical for the two problems and results of interest are obtained when the transformed boundary conditions can be physically interpreted. In this manner it is shown, for example, that flywheel on a uniform shaft can be transformed into a flexible coupling and a mass carried on a uniform beam into a flexible hinge. In the second, the connection is established by use of the concept of mechanical admittance. Here the frequency equations are simply related but the frequencies are not
The evaluation of matrix elements for the analysis of swept-back wing structures by the method of oblique coordinates
No full textThis report is an addition to the college of Aeronautic Report No. 31. The purpose of the report is to enable one to obtain the matrix elements used in the analysis of swept-back wing structures by oblique coordinated in a very rapid manner
Tests on the general instability of a stiffened metal cylinder under axial compression
No full textA thin stiffened metal cylinder liable to General Instability was tested under axial compression and an investigation was made into possible methods of predicting the critical load from non-destructive tests. Particular attention was paid to the perturbation loading technique. The cylinder was finally tested to destruction and the actual failing load compaired with the values given by various theories and empirical relationships
The numerical solution of certain differential equations occurring in Crocco's theory of the laminar boundary layer
No full textA numerical method is described for the solution of certain differential equations which result from the application of Crocco’s transformation to the laminar boundary layer equations appropriate to high supersonic Mach numbers. (i.e. at hypersonic speeds). Continues
The economics of aircraft production : a study of the control of overhead costs in aircraft manufacture
No full textThis paper represents an attempt to appraise the different factors which must be considered in applying modern methods of cost control to aircraft production, and to suggest those positive measures best calculated to effect such control. The emphasis throughout is on control of overhead costs as these are by far the largest element in the total cost make-up
Note on the results of some profile drag calculations for a particular body of revolution at supersonic speeds
No full textDetails additional to those discussed in College of Aeronautics Report No. 73 are given of the method developed for the calculation of the profile drag of bodies of revolution at supersonic speeds and zero incidence. The method has been applied
to a particular body of fineness ratio 7.5 (see Fig. 1) for Mach
numbers ranging from 1.5 to 5.0, Reynolds numbers ranging from
106 to 108 and transition positions ranging from the nose to the
tail end of the body. The calculations assume zero heat transfer.
The results indicate that the overall difference in profile drag
between fully laminar and fully turbulent flow decreases rapidly
with mainstream Mach number and rather more rapidly than does the corresponding difference for a flat plate, and at Mach numbers greater than about 2 the profile drag of the body with fully
turbulent flow is less than that of a flat plate (Fig. 14)
An assessment of certain methods of stress-analysis of rectangular multi-web box beams
No full textThe stress distribution in an unswept multi-web box under shear load applied at the centre of a rigid tip rib is examined, and compared with results obtained by a method which replaces the shear webs by a shear-carrying continuum. Continues ..
The response time of wind tunnel pressure measuring systems
No full textThe time response of a wind tunnel pressure measuring system,
comprising a pressure transducer of fixed volume and a length of
capillary tubing, is analysed and the results compared with experiments.
It is shown that the approximate analysis of Kendall (1958), in which
the friction losses at any given time are assumed equal to the steady
state losses, has a wide range of validity, provided the L/R ratio for
the capillary tube is large and the inlet and exit losses are included
as equivalent lengths of the capillary tube
The compressible laminar boundary layer with foreign gas injection
No full textThe equations of the steady compressible two-dimensional laminar boundary
layer with foreign gas injection through a porous wall are solved, using an
extended form of Lighthill's approximate method, for arbitrary main stream
pressure gradient, wall temperature and injection velocity. The wall shear
stress and heat transfer rate are obtained in the form of equations suitable
for iteration.
It is shown that substantial reductions in skin friction and heat transfer rate
can be obtained by the injection of a light gas instead of air