A Lightweight Split-Torque Transmission for a 330 KW Helicopter

A simple split-torque gear train is used as the main rotor transmission of a single-engine helicopter. Overall speed reduction ratio achieved is 103:1 between the engine at a nominal 36 000 rev/min and the main rotor at 350 rev/min. This ratio is generated from three stages of fixed-axis gear trains containing only eight gears. Alternative configurations are outlined and discussed. Comparison with a current production design shows the split torque arrangement offers reductions in weight, height, and drive train losses. A low total of gears and bearings offers the potential for improved reliability.

Prediction Methods for Entry Length Heat Transfer by Combined Laminar Convection in Horizontal Tubes

Numerical prediction methods for calculating velocity and temperature distributions in heated ducts can be made accurately but are time consuming. The paper shows possible simplifications, including the neglect of the buoyancy term, and the resultant accuracy attained. The case studied is for laminar flow, entry length heat transfer in horizontal tubes with constant rate heat flux. Comparison is made between experimental results, a full solution and an approximation based on a series of truncated versions of the fully developed temperature profile. Calculations are made both with and without variation of thermophysical properties with temperature.

Total Project Management: An Integrated Approach to the Management of Capital Investment Projects

Substandard performance and failure to meet objectives in capital investment has been a major contribution to the catastrophic decline in the profitability of industry in the UK. The structure of a project is described and the differences between a project and ongoing operations are discussed. An approach to capital investment analysis is described which is based on rate of cashflow and which relates closely to the actual events that occur. The nature and character of the risks involved are examined and a variety of problems discussed. The inevitability of the learning process is pointed out together with the benefits of structuring this learning. Some of the human and organizational imperatives required for success are defined and the need for a knowledge-based approach to the main project disciplines is advocated. These disciplines are outlined together with some discussion of their inter-relations. The operational techniques which ensure a total, and avoid a fragmented, approach to managing a project are briefly described and the importance of top management involvement is emphasized. By taking the steps advocated in the paper the risks inherent in capital investment projects can be reduced to an acceptable level.

Predicting Cutting Forces for Oblique Machining Conditions

Using orthogonal (plane strain) machining theory together with certain simplifying assumptions based on experimental observations it is shown how the three components of cutting force in oblique machining can be predicted from a knowledge of the work material flow stress and thermal properties and the cutting conditions. A comparison of predicted and experimental cutting force results is given.

The Effect of Joint Flexibility on the Torsion of a Vehicle Body

Experiments on thin fabricated box members in a tee joint configuration revealed deformations which could not be correlated with beam-type models, even when spring elements were introduced at the joint. The behaviour was also observed in finite element analyses of the joints. Part of the cab structure of a heavy goods vehicle which formed a plane frame with fabricated members of closed cross-section was tested in torsion and the stiffness compared with theoretical predictions. The application of classical beam and torsional theory gave a result which was approximately ten times the experimental value. A further theoretical estimate, which included the joint flexibility as predicted by a finite element model of the localized region at the joint, gave an improved result which was 26 per cent higher than the experimental value.

Submarine Propulsion in the Royal Navy

The paper outlines the history of submarine propulsion from the early days, through the hydrogen peroxide plants on Explorer and Excalibur to the setting up of the nuclear submarine programme. The building of the submarine prototype at Dounreay, the purchase of the Dreadnought plant from the US and the design and construction of the Valiant class submarines formed the base for developments in the 1960s leading to the highly successful Resolution and Swiftsure class submarines. Lessons learned from the design, building and operation of nuclear submarine propulsion plants are discussed and the future requirements for unproved operational characteristics and for higher nuclear safety standards are examined against the constraints of keeping unit costs under control. The success of the nuclear submarine programme is shown by the position today where the Royal Navy has sixteen nuclear submarines in service, a new submarine class under construction and work on the next generation of nuclear propulsion plants well advanced.