CoA. Reports

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Open Access
Ablation studies of low melting point bodies in a pre-heated supersonic air stream
(College of Aeronautics, 1960-02) Cleaver, J. W.
This report is an investigation into the melting of axi-symmetric and two-dimensional bogies at a Mach No. of M[infinity] = 1.78 and stagnation temperatures up to 550 [degrees]K. In this temperature range, the most suitable material for the models was found to be an eutectic tin-lead alloy a melting point of 456 [degrees]K. For the cone and hemisphere-cone models two distinct modes of melting were observed. In cases where the estimated equilibrium surface temperature (Tw)o was approximately equal to the material melting temperature Tm, melting occurred only at the stagnation point of the model and was such that a flat surface normal to the gas stream always resulted. If the average rate of heat transfer at the air-liquid interface be defined as qi = LmPm x, where Lm is the latent heat of fusion, Pm is the density of the material and x is the rate of recession of the flat surface, it is found that qi decreases with increase of the radius of the flat nose. A very approximate theory is found to show some agreement with the experimental rates of heat transfer. When (Tw)o was considerably greater than Tm the flat surface was no longer preserved and the resulting steady ablating shape was paraboloidal in nature. When this occurred x was usually constant. This allowed some average steady state heat transfer rates to be evaluated and compared with theory. Preliminary tests were also made with a two-dimensional wedge model.
Open Access
Addendum to a theoretical and experimental study of the boundary layer flow on a 45 degrees swept back wing
(College of Aeronautics, Cranfield, 1957-11) Walton, J.
COA report 109 describes Flight Tests carried out on a swept back half wing of double elliptical section to investigate the nature of the boundary layer flow, with particular reference to Bounday Layer Instability and subsequent transition.
Open Access
Addendum to type record. Avro "Lancaster" Mk.1 P. A. 474 Type record No. 1/P1/Lancaster. Investigation of boundary layer conditions on wings. M.O.S. Contract No.6/Aircraft/9807/C. B. 6(a)
(College of Aeronautics, 1956-01) College of Aeronautics, Department of Aircraft Design
Introduction The investigation involves, briefly, the mounting of a wing of 45' sweep-back in a dorsal position on the fuselage of 'Lancaster' P.A.474 such that wing incidence will be variable in flight over a 20 range, i.e. ± 100. A ‘partial chord’ technique for swept wings has been established by the College using a similar wing mounting configuration on an Avro 'Anson' Aircraft and this technique has been applied to the current investigation.
Open Access
Aerodynamic characteristics of a hypersonic parachute
(College of Aeronautics, 1961-11) Boyd, E. A.
Newtonian theory, both in the form of the Modified-Newtonian and the Newton- Busemann pressure laws, is used to find the shape, cloth area and drag of the axisymmetric canopy of a hypersonic parachute, whose only load-carrying fibres are longitudinal ones. As an example, an estimate is made of the size of canopy needed to give a drag of 20,000 lb. in flight at a Mach number of 10 at 100,000 feet altitude.
Open Access
Aerodynamic characteristics of a swept wing with spanwise blowing.
(Cranfield University, 1956-09) Ayers, R. F.; Wilde, M. R.
This report is the first of a series of studies to investigate the effectiveness of a spanwise blowing on the aerodynamic characteristics of low aspect ratio wings and bodies. The model used in this investigation was an untapered half-wing aspect ratio 1.39,50 degree sweep back, and mounted on a reflective plate.
Open Access
The aerodynamic derivatives of an aerofoil oscillating in an infinite staggered cascade
(College of Aeronautics, 1960-01) Craven, A. H.
Thin aerofoil theory is used to obtain, in integral form the aerodynamic derivatives of an aerofoil oscillating in an infinite cascade. The theory allows for arbitrary stagger angle and phase difference between adjacent blades of the cascade. The expressions obtained reduce, for zero stagger and for in phase and antiphase oscillations, to known results.
Open Access
The aerodynamic derivatives with respect to rate of yaw for a delta wing with small dihedral at supersonic speeds
(College of Aeronautics, Cranfield, 1949-03) Hunter-Tod, J. H.
Expressions are derives for the yawing derivatives on the assumptions of the linearised theory of flow for a delta wing with small dihedral flying at supersonic speeds at small incidences. The non-dimensional derivatives are numerically decreasing functions of Mach number. The non-dimensional rolling and yawing derivatives are also numerically decreasing functions of aspect ratio. When the wing lies entirely within the apex Mach cone there is a leading edge suction force proportional to incidence which makes a destabilising contribution to the yawing moment and side force which may be of the same magnitude as that from the inducted excess pressure distribution.
Open Access
The aerodynamic derivatives with respect to sideslip for a delta wing with small dihedral at supersonic speeds
(College of Aeronautics, 1947-12) Robinson, A.; Hunter-Tod, J. H.
Expressions are derived for the sideslip derivatives on the assumptions of the linearised theory of flow for a delta wing with small dihedral flying at supersonic speeds. A discussion is included in the appendix on the relation between two methods that have been evolved for the treatment of aerodynamic force problems of the delta wing lying within its apex Mach cone. Continues…
Open Access
Aerofoil theory for swallow tail wings of small aspect ratio
(College of Aeronautics, Cranfield., 1950-10) Robinson, A.
A method is developed for the calculation of the aerodynamic forces acting on a ‘swallow tail’ wing of small aspect ratio. Lift, induced drag, and aerodynamic centre position of simple swallow tail wings (Fig. 1 (b)) are computed as an application. For a given incidence, lift and induced drag are, within the limits of the theory, proportional to aspect ratio and independent of speed. The chordwise life distribution rises linearly from zero at the apex, drops rapidly in the region of the root chord trailing edge, and then decreases gently to zero.
Open Access
Aileron reversal and divergence of swept wings with special consideration of the relevant aerodynamic and elastic characteristics
(College of Aeronautics, Cranfield, 1952-03) Radok, J. R. M.
Using oblique coordinates, the static problems of Aero-elasticity for swept wings are reduced to the solution of integral – or matrix equations, which may be solved by iteration. The present treatment also indicates the suitability of integral equations for fundamental aero-elastic investigations. Continues …
Open Access
The air resistance of racing cyclists
(College of Aeronautics, Cranfield, 1956-10) Nonweiler, T.
Tests in the closed-section wind-tunnel on three different cyclists mounted on a racing bicycle are described, and figures quoted for the recorded air resistance. Some comments are also included on the implications of the results concerning the power-output of racing cyclists.
Open Access
Analysis of experiments on swept wing structures
(College of Aeronautics, Cranfield, 1953-05) Howe, D.
This report is concerned with the application of various theories to the solution of problems investigated experimentally, and in some cases theoretically, by others at the College of Aeronautics. Continues …
Open Access
The analysis of reinforced circular and elliptical cutouts under various loading conditions
(College of Aeronautics, 1961-07) Houghton, D. S.; Rothwell, A.
The effect of reinforced cutouts in a plane sheet under various loading conditions is considered, and a number of experimental results are given for circular and elliptical cutouts with a uniform plate reinforcement, subjected to various systems of biaxial tension and pure shear. These experiments were conducted using a plane loading frame, and the results are compared with the theoretical plane stress solution. For the circular cutout the effect of neglecting the bending stiffness of the reinforcement is considered. Some additional experiments were carried oUt on a 60 in. diameter pressurised cylinder containing an elliptical hole reinforced according •to Mansfield's neutral hole theory. The strains in the sheet in the region of the neutral hole are .compared with the corresponding strains in the uncut sheet. The experimental results obtained generally show a good agreement with the theory.
Open Access
Analysis of two-cell swept box with ribs parallel to the line of flight under loading by constant couples
(College of Aeronautics, Cranfield, 1953-03) Howe, D.
The method of oblique co-ordinates is used to analyse the problem associated with the strength and deformation of a uniform, rectangular, two- cell swept box beam having ribs parallel to the line of flight. The case of loading by constant couples is considered, but no account of root effects is taken. Continues…
Open Access
The application of memo-motion to industrial operations
(College of Aeronautics, Cranfield., 1954-12) Norbury, C. J.
Memo-Notion, or Spaced Shot Photography, was introduced as a tool of Work Study Dr. Mundel, then of Purdue University, in 1946, as a means of reducing the cost of film analysis on long operations by using a camera driven by a geared down electric motor, giving exposures every second. Since its introduction Memo-Motion has been applied to a limited extent in the U.S.A., but it is not known to be in use at all in England.
Open Access
Application of the linear perturbation theory to compressible flow about bodies of revolution
(College of Aeronautics, Cranfield, 1947-09) Young, A. D.; Kirkby, S.
The linearised theory is developed in some detail in order to clarify the differences between two-dimensional and axi-symmetric flow. In agreement with other authors it is concluded that the perturbation velocity on a thin body of revolution in compressible flow is 1/β2 times the perturbation velocity in incompressible flow on a thinner body at reduced incidence obtained by reducing the lateral dimensions of the original body in the ratio (3:1). This result is applied to a representative family of streamline bodies of revolution at zero incidence. Continues…
Open Access
An approximate solution of the turbulent boundary layer equations in incompressible and compressible flow
(College of Aeronautics, 1960-07) Lilley, G. M.
If over the ‘outer’ region/ of the boundary layer, where the mean velocity varies but little from its value outside the shear layer, a virtual eddy viscosity is defined, which is constant over the outer region but varies in the direction of the mainstream, a solution of the turbulent boundary layer equations can be found which satisfies the appropriate boundary conditions. The solution leads to a compatibility condition for the virtual eddy viscosity in terms of the wall shear stress, the boundary layer momentum thickness and the mainstream velocity, at least for the case of a constant external velocity. [...cont.]
Open Access
An approximate solution to the swept wing root constraint problem
(College of Aeronautics, Cranfield, 1956-02) Howe, D.
This report presents an approximate solution to the problem associated with the root constraint in a swept wing.
Open Access
An assessment of certain methods of stress-analysis of rectangular multi-web box beams
(College of Aeronautics, Cranfield, 1956-12) Griffin, K. H.
The 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 ...
Open Access
Assessment of errors in approximate solutions of differential equations
(College of Aeronautics, Cranfield, 1947-12) Duncan, W. J.
The term assessment is applied to any process which enables us to set rigid bounds to the error or to estimate its value. It is shown that upper and lower bounds can be assigned whenever the Green's function of the problem is one- signed; this is true in many important problems. Another method is applicable to step by step -solutions of ordinary differential equations, linear or non-linear, and depends on use of the "index" of the process of integration. Lastly, the error in a linear problem can be estimated when an approximation to the Green's function is known.