A convenient method is pointed out for calculating the response of a damped linear system with one degree of freedom to harmonic excitation. Results of such calculations are usually represented by the familiar “ resonance curves ”—one curve being plotted for each intensity of damping. These curves are not particularly convenient to use and Yates has overcome several of their defects by throwing them into a nomographic form. Yates' nomogram is based upon the concept of viscous damping and it does not give the information of a conventional set of resonance curves in that it relates to the velocity of vibration. By changing over to hysteretic damping, a nomogram of somewhat similar form may be constructed such that it gives amplitudes and phase angles of displacements while retaining the advantages, over resonance curves, of this form of representation.

The fuel control system for a modern gas turbine engine has to meet far more stringent requirements than demanded by early engines. To achieve greater efficiency the controlling parameters such as pressure and temperature must be measured and acted upon with a greater degree of accuracy. A 5°C change in turbine entry temperature can cause a 200 hour decrease in the life of a turbine with an expected life of 2000 hours. With increased fuel efficiency, a saving of less than 1% in fuel consumption is a vital economic factor. These higher demands can be met in most instances by mechanical or hydromechanical fuel systems but the problems of these systems such as hysteresis, friction, fuel temperatures and coefficients of expansion increase rapidly with the search for higher performance. The complexity and number of moving parts becomes greater and so the system is commensurately less reliable.

Willy Messerschmitt’s most notable impact on aviation history occurred during the wartime period 50 years ago. While there is a general belief that the business approach under the extraordinary circumstances of this period is in no way relevant to today’s business environment, this paper will, nevertheless, attempt to illustrate that some elements of Messerschmitt’s approach may still be worthy of consideration.

Messerschmitt’s approach had not been that of “big business” but rather comparable to that of an artist-craftsman. Since the approach of an artist is best reflected by reviewing his “oeuvre”, this paper will be proceeding accordingly. Figure 1 shows Messerschmitt in 1935.

The Quasi-Cylinder and slender body theories for the supersonic flow past bodies of revolution have been much used in recent years because, for reasonably simple body profiles, these theories permit a simple and rapid calculation of the first-order pressure distributions and aerodynamic forces. It is assumed in both theories that the body profile slope is small; in the quasi-cylinder theory it is also assumed that the body radius is nearly constant, whereas in the slender body theory it is assumed that the thickness ratio of the body (maximum diameter/length) is small.

In the present note these two theories are combined completely. From a strictly mathematical point of view nothing is gained by this combination, and, furthermore,application of the combined theory to a particular case is in general a little more laborious than application of either of the original theories.

This paper focuses on the problem of skin corrosion on the upper wing surfaces of rib-stiffened aircraft. For maritime and military transport aircraft this often results in multiple co-located repairs. The common approach to corrosion damage in operational aircraft is to blend out the corrosion and rivet a mechanical doubler over the region. In particular this paper describes the results of a combined numerical and experimental investigation into the ability of the additive metal technology, Supersonic Particle Deposition (SPD), to restore the load-carrying capacity of rib-stiffened wing planks with simulated skin corrosion. The experimental results reveal that unrepaired skin corrosion can result in failure by yielding. The experimental results also reveal that SPD repairs to skin corrosion can restore the stress field in the structure, and can ensure that the load-carrying capability of the repaired structure is above proof load.

You can pick up almost any history of aviation—from the early times to the present—and read of the exploits and adventures of pilots and their planes. Sir Charles Kingsford-Smith and his Fokker, Charles Lindbergh and his Ryan, Amelia Earhart and her Lockheed. We who have technical interests in aviation know that Kingsford- Smith and Lindbergh depended on their Whirlwinds, and Miss Earhart on a Wasp, but the popular stories often fail to make that point.

In more modern times, the engines are equally vital but sometimes get overlooked. Once, when a new jet aircraft was being announced at a press briefing, an airline officer breathlessly described the aircraft, showed artists’ concepts of the cabin and flight deck, and talked at length of the systems and subsystems. After an hour-long description, he called on his audience of reporters, and then he got his come-uppance from an engine man’s point of view. A reporter at the back of the room was recognised, and asked: ‘And what is this aircraft going to be? A glider?’ The by now red-faced official had neglected to mention the powerplants.

Elastomeric and Fluidlastic® absorbers are proposed to be embedded in blade cavity to reduce troublesome second harmonic flap-wise blade loads of rigid rotors. A simple model of a blade with a flap-wise dynamic absorber is derived to investigate centrifugal force effects on the absorber's rotating frequency. The system's dynamic equations of motion indicate that centrifugal force has no effect on absorber's frequency under rotation. Aeroelastic simulation of the coupled rotor and absorber system based on an elastic beam model in generalised force formulation is used to explore load reduction extent and dynamic absorber behaviour. At a forward speed of 200 km/h, the elastomeric absorber reduces the second harmonic flap-wise root-bending moment by 88.8% for unacceptably large stroke; the Fluidlastic® absorber reduces the moment by 78.5% with a stroke 4.26% of blade chord length. Results indicate that placing an embedded Fluidlastic® absorber in the blade's flap-wise direction has potential for reducing load in different flight states with relatively small strokes. Increasing tuning port area ratio or Fluidlastic® absorber mass can distinctly decrease strokes without increasing loads. However, deviation from normal rotor speed significantly lowers Fluidlastic® absorber performance.

The objective of design is the production of manufacturing drawings which are right. This objective will rarely be achieved without first making mistakes which require experiment to rectify so that design is the work of a team which includes designers who draw, development engineers and experimental manufacturing operatives.

Design must have an output which can be valued and the value of the output must exceed its costs. In the aircraft industry, the cost of design is a considerable part of the cost of the product and must be recovered directly from the customer. Because underestimating the cost of design is endemic and because some work done to obtain orders will not be successful, not all cost of design can be recovered from the customer and so some costs must be written off.

In considering the spectrum of possibilities which advances in electronics offers during the next fifty years it is worth a short backward glance over an equal time span.

In 1918 the use of electronics was almost entirely devoted to developments in the radio frequency field, principally those of communication and sound amplification. Wireless telegraphy under pressure from naval and merchant marine requirements had reached the stage where it formed a dependable means of communication, albeit with the need for specialised human skills, for the world's modern shipping.

There had been a limited amount of aeronautical radio development during the war, to reduce the size and weight of wireless telegraphy and the later radio telephony transmitters; much of the later stages of this work was carried out at Biggin Hill. However, these developments had scarcely any influence upon either the design and construction of aircraft or perhaps more important only a small influence on their operation. It was to be sometime before the exploitation of the radio frequency spectrum on the ground and in the air contributed to increase greatly the operational capability of the aeroplane during the 1930's.

In the past the usual method of dealing with the articulated rod has been to treat the problem graphically. Although this method may be sufficiently accurate for a first approximation the inherent difficulties often lead to serious errors after the first few stages. A graphical method is always sufficiently accurate to determine the travel of a piston operated by an auxiliary rod ; but, the double differentiation of the displacement curve by graphical means (to obtain the acceleration curve), is not only inaccurate but a long and tedious operation.

To remedy this defect a Fourier's series has been developed which can be differentiated at sight and which gives a remarkable accuracy.

The geometrical properties of the mechanism have been analysed and thus equations are formed giving the resultant radial and tangential components at the crank pin, the bending forces and tensions on the master rod, etc.

Minitufts are increasingly used for flow visualisation on static wind tunnel models because they can be applied in larger numbers for increased detail and with less interference compared with conventional tufts. This Memorandum describes an extension of their use to continuously rotating models where the heavier conventional tufts are inadequate.

Tests on two combat aircraft models in the 4 m x 2.7 m Low Speed Wind Tunnel are described. Measured variations of rolling moment are explained with the aid of the minituft photographs.

The present time, when the prospect of high speed flight often seems to recede, not to approach, may well be a good occasion to review the ram-jet, an engine whose main use is at high flight speed. We owe the succinct name “ ram-jet” to the Americans and the original idea to the French. But despite the admirable efforts abroad this paper is most concerned with British ideas, especially and naturally with those conceived and prosecuted at the National Gas Turbine Establishment. At the outset it is appropriate to acknowledge all the separate personal contributions to the subject of this paper and the assistance of my colleagues in preparing some of the information presented.

In several recent reports reference is made to spanwise variations in the boundary layers growing in the working sections of various wind tunnels. Systematic investigations by Patel, Bradshaw and de Bray are in general agreement that these variations are caused by the screens which are fitted into the settling chambers of these tunnels to dampen out non-uniformities in the upstream flow. They conclude from their experiments that these variations will be much reduced if the downstream screen (or preferably the two downstream screens) has an open area ratio greater than about 0·57 and that these should be followed by a honeycomb to obtain the most steady and uniform flow, although a honeycomb in this position may increase the turbulence level in the working section.

This article presents a unified approach to solve steady-state conjugate heat-transfer problem including simultaneously gas, liquid and solid regions in just one 3D domain, distinguished by their particular properties. This approach reduces approximation errors and the time to solve the problem, which characterise iterative methods based on separated domains. The formulation employs RANS equations, realisable k-ε turbulence model and near-wall treatment model. A commercial CFD code solves the pressure-based segregated algorithm combined with spatial discretisation of second order upwind. The problem consists of a convergent-divergent metallic nozzle that contains cooling channels divided in two segments along the wall. The nozzle wall insulates the high-speed hot air flow, dealt as perfect gas, from the two low-speed cold water flows, dealt as compressed liquid, both influenced by transport properties dependent of the local temperature. The verification process uses three meshes with increasing resolutions to demonstrate the independence of the results. The validation process compares the simulation results with experimental data obtained in high-enthalpy wind tunnel, demonstrating good compliance between them. Results for the bulk temperature rise of the water in the second cooling segment of the nozzle showed good agreement with available experimental data. Numerical simulations also provided wall temperature and heat flux for the gas and liquid sides. Besides, distribution of temperature, pressure, density and Mach number were plotted along the nozzle centerline showing a little disturbance downstream the throat. This phenomenon has been better visualised by means of 2D maps of those variables. The analysis of results indicates that the unified approach herein presented can make easier the task of simulating the conjugate convection-conduction heat-transfer in a class of problems related to regeneratively cooled thrust chambers.