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THIS paper is based on the 16th R. J. Mitchell Memorial Lecture presented to the Southampton Branch of the Royal Aeronautical Society at Southampton University on March 5, 1969, by the author.

A study of the main parameters to be resolved for civil V/S.T.O.L. aircraft, the necessity for all weather operation, the airport requirements and the competition from other forms of transport. FROM a choice of a wide range of V/S.T.O.L. applications, this paper is concerned with the civil aircraft aspects. It deals with the main parameters to be studied in resolving V.T.O.L. and S.T.O.L. aircraft characteristics, the weighting of these toward favourable performance and to meeting the proposed certification rules for this form of transport. The part to be played by electronics in all weather operations is also discussed. Competition from surface transport, and V/S.T.O.L. airport requirements are referred to, and some general characteristics of the many different aircraft configurations are discussed. Some conclusions are reached suggesting the direction and weighting of future work.

Europe has adopted the Flight Path 2050 (FP2050) challenge demanding that by 2050, 90 per cent of the travelers are able to reach door-to-door destinations in Europe within four hours. A hypothesis can be formulated that without the Small Air Transport (SAT) system, optimized for short distances and for multiple but narrow passenger flows, this challenge cannot be met.

This paper defines design goals and necessary research focused on small aircraft concepts, as a required condition to fulfil the FP2050 challenge “90 per cent d2d 4h”.

The new small aircraft concepts have been defined as SAT Aircraft Family Program. Three demonstrators with common modules could be proposed: two using the same turboprop engine (first, one engine, 9 passengers; second, two engines, 19 passengers) and third demonstrator could be with a diesel hybrid engine.

The SAT Aircraft Family Program depends on demand optimized for specific regional features (passenger flows, passenger time value spectrum and infrastructure) and a set of matured technologies as a result of Clean Sky 2 (CS2) devoted to SAT.

This practical implications consist of developing on SAT technologies in CS2, deploying the demonstrators by the small aviation industry and launching an SAT system pilot phase.

FP2050 has changed the approach to a citizen-oriented from an atomized technologies taxonomy-oriented one. The challenge “90 per cent d2d 4h” also covers the needs of remote regions. This niche could be filled by the SAT system using the small aircrafts family.

The paper value is in defining entry requirements, answering how to build the SAT Aircraft Family Program satisfying the FP2050 challenge “90 per cent d2d 4h”.

A review is attempted with the objective to indicate the most promising aeronautical technology for application to future subsonic civil transport aircraft.

A methodology is put forward, according to which direct operating costs (DOC) are examined in order to identify those that can be reduced, and, then, specific technology is assessed in relation to its efficiency in reducing these DOC, operational feasibility and cost‐effectiveness.

This assessment suggests the selection of propfan and powered lift as the leading future aeronautical technology. These findings are supported by a comparison of a number of advanced technology designs.

Provides a starting point for further investigation of advanced aeronautical technology and unconventional configurations for large subsonic civil transport aircraft.

TO say that the Twenty‐fourth S.B.A.C. Show was an unqualified success is perhaps to gild the lily. True there were disappointments— the delay which kept the TSR‐2 on the ground until well after the Show being one—but on the whole the British industry was well pleased with Farnborough week and if future sales could be related to the number of visitors then the order books would be full for many years to come. The total attendance at the Show was well over 400,000—this figure including just under 300,000 members of the public who paid to enter on the last three days of the Show. Those who argued in favour of allowing a two‐year interval between the 1962 Show and this one seem to be fully vindicated, for these attendance figures are an all‐time record. This augurs well for the future for it would appear that potential customers from overseas are still anxious to attend the Farnborough Show, while the public attendance figures indicate that Britain is still air‐minded to a very healthy degree. It is difficult to pick out any one feature or even one aircraft as being really outstanding at Farnborough, but certainly the range of rear‐engined civil jets (HS. 125, BAC One‐Eleven, Trident and VCIQ) served as a re‐minder that British aeronautical engineering prowess is without parallel, while the number of rotorcraft to be seen in the flying display empha‐sized the growing importance of the helicopter in both civil and military operations. As far as the value of Farnborough is concerned, it is certainly a most useful shop window for British aerospace products, and if few new orders are actually received at Farnborough, a very large number are announced— as our ’Orders and Contracts' column on page 332 bears witness. It is not possible to cover every exhibit displayed at the Farnborough Show but the following report describes a wide cross‐section beginning with the exhibits of the major airframe and engine companies.

The growth in air mobility, rising fuel prices and ambitious targets in emission reduction are some of the driving factors behind research towards more efficient aircraft. The purpose of this paper is to assess the application of a blended wing body (BWB) aircraft configuration with turbo-electric distributed propulsion in the military sector and to highlight the potential benefits that could be achieved for long-range and heavy payload applications.

Mission performance has been simulated using a point-mass approach and an engine performance code (TURBOMATCH) for the propulsion system. Payload-range charts were created to compare the performance of a BWB aircraft with various different fuels against the existing Boeing 777-200LR as a baseline.

When using kerosene, an increase in payload of 42 per cent was achieved but the use of liquefied natural gas enabled a 50 per cent payload increase over a design range of 7,500 NM. When liquid hydrogen (LH2) is used, the range may be limited to about 3,000 NM by the volume available for this low-density fuel, but the payload at this range could be increased by 137 per cent to 127,000 kg.

The results presented to estimate the extent to which the efficiency of military operations could be improved by making fewer trips to transport high-density and irregular cargo items and indicate how well the proposed alternatives would compare with present military aircraft. There are no existing NATO aircraft with such extended payload and range capacities. This paper, therefore, explores the potential of BWB aircraft with turbo-electric distributed propulsion as effective military transports.

To provide for the use of airlines and other civil aviation organizations a practical definition of operational efficiency and to show how it can be determined.

A brief account of air transport economics is used to demonstrate how bom load factors and aircraft utilization need to be considered in assessing operational efficiency. Then other efficiencies are treated briefly before an example is given of how the better of two fictitious aircraft can be chosen for a particular route. A second example involving the calculation of the operational efficiency achieved by an imaginary airline is also given to show that the typical value is lower than might be expected, particularly in view of the relatively high load factors involved.

Provides performance values and economic figures which are typical of current airline operations.

Use of the proposed definition will allow the consistent assessment of the economic performance of airlines.

At present there is no definition of operational efficiency in general use although it is greatly needed by airlines. The definition proposed in this paper is practical and easy to use.

The purpose of this paper is to propose a solution of the engine bypass ratio choice problem of a very light jet (VLJ) class aircraft using the multiple objective optimization (MOO) method.

The work focuses on the choice of one of the most essential parameters of the jet engine, that is its bypass ratio. The work presents the methodology of optimal designing using the multitask character of the matter which is based on the mathematical model of optimization in the concept of the set theory. To make an optimal choice of the chosen parameter, a complete computational model of an aircraftwas made (aerodynamic, power unit, performance and cost) and then the method that allows to choose the bypass ratio was selected, regardingmultiple estimating criteria of the obtained solutions. The presented method can be used at the concept design state for determining the chosen and most important technical parameters of the aircraft.

The way to design a competing aircraft is to choose its design parameters, including the power unit, by using the advanced methods of MOO. The main aim of the work was to demonstrate a method of selecting chosen parameters of the transport aircraft at the preliminary design stage. The work focuses on the choice of bypass ratio of the jet engine of the VLJ. The method could be helpful at the preliminary design stage of a new aircraft to selection of other design parameters.

The exemplary calculations were made for 50 different transport tasks to take into account different performance conditions of the aircraft. The presented method can be used at the concept design state for determining the chosen and most important technical parameters of the aircraft.

The work shows a practical possibility to implement the proposed method. The presented method could be helpful at the preliminary design stage of a new aircraft to select its design parameters. The results of the analyses are a separate point for further research and studies.

The work shows a practical possibility to implement the proposed approach for design problems at early stages of product development.

EACH September the eyes of the aeronautical World turn towards the S.B.A.C. Air Display and Exhibition with interest unequalled by any other event. It is fitting that the Display is now held each year at the airfield of the Royal Aircraft Establishment, one of the world's most prominent aeronautical research centres. This interest becomes increasingly keen too, as the preview day comes closer, because new prototypes of unorthodox designs often appear a short time before the Show to illustrate the results of years of careful planning, development and research of the particular company. These designs often mould the path of progress for smaller countries without the economic resources to forge the way ahead alone. Most British citizens are very proud of their country's place in aviation today, both in the military and civil fields. This is understood by most foreigners because it is clear that Britain has won a place in aeronautical development second to none.