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The ratio of the energy liberated during a flight to the revenue work done (ETRW) of an airplane can be employed as a key indicator to assess its environmental impact. It remains constant during the life cycle of the aircraft and is fixed by its designers. The goal of an environmentally optimum airplane is to minimize the ETRW. This paper seeks to address these issues.

For an existing airplane, there are two major parameters that can greatly affect the ETRW, which are the ratio of actual payload to maximum possible payload “c” and the flight range R. The goal of this paper is to study the effect of c and R on ETRW and minimize it by using a genetic algorithm (GA). The study is performed on a Boeing 737‐800 and a Boeing 747‐400 aircraft as well as recently proposed aircraft designs, namely the Boeing second generation Blended‐Wing‐Body (BWB) and MIT Double‐Bubble D8.2.

It turns out that the maximum possible values of payload and range do not necessarily lead to a flight with minimal environmental impact. For new aircraft designs, the minimization of ETRW should account for advances in materials, alternative fuels, structures, aerodynamics and propulsion technologies which can be taken into consideration at the design stage.

It should be noted that other factors which also affect the emissions, namely the aircraft operations and air traffic management, are not included in the ETRW.

The optimization study is valuable in determining the payload and range of an existing aircraft or a new aircraft configuration for minimal environmental impact.

The ratio of the energy transformed to the revenue work done (ETRW) during a flight of an airplane can be employed as a key indicator to assess its environmental impact. It remains constant during the life cycle of the aircraft and is fixed by its designers. The goal of an environmentally optimum airplane is to minimize the ETRW.

For an existing airplane, there are two major parameters that can greatly affect the ETRW, which are the ratio of actual payload to maximum possible payload “c” and the flight range R. The goal of this paper is to study the effect of c and R on ETRW and minimize it by using a genetic algorithm (GA). The study is performed on a Boeing 737-800 and a Boeing 747-400 aircraft as well as recently proposed aircraft designs namely the Boeing second-generation Blended-Wing-Body (BWB) and MIT Double-Bubble D8.2.

It turns out that the maximum possible values of payload and range do not necessarily lead to a flight with minimal environmental impact. For new aircraft designs, the minimization of ETRW should account for advances in materials, alternative fuels, structures, aerodynamics and propulsion technologies which can be taken into consideration at design stage.

It should be noted that other factors which also affect the emissions, namely the aircraft operations and air traffic management, are not included in the ETRW.

The optimization study is valuable in determining the payload and range of an existing aircraft or a new aircraft configuration for minimal environmental impact.

ONE of the most important tasks of present‐day aeroplane manufacture is the design of economical high‐speed commercial aeroplanes to provide regular and safe services.

Development of the Lockheed supersonic transport has followed the basic philosophy that an advance in air travel in terms of speed and economics should be accompanied by similar advances in aeroplane safety and flying qualities. To achieve these objectives, Lockheed's SST design work has been concentrated for many years on the development of a fixed‐wing design. The present configuration—called a double delta—provides a simple high lift system with low wing loading, excellent low speed stability and control, and large favourable ground effects in landing, with inherent advances in operational simplicity and safety.

This book is an extension of a series of lectures given at the Institute of Aeronautics of the University of Brussels. It gives the aerodynamic theory of the helicopter rotor in complete detail, and with some 130 sketches, diagrams, graphs and photographs, and the reader need not have any previous knowledge of the subject.

THERE have been two previous James Forrest Lectures dealing with aeronautics. In 1912, Mr. Mallock addressed this Institution on “Aerial Flight,” and in 1914, Dr. Lanchcster took as his subject “The Flying‐Machine from an Engineering Standpoint.”

Under this heading are published regularly abstracts of all Reports and Memoranda of the Aeronautical Research Council, Reports and Technical Memoranda of the United States National Advisory Committee for Aeronautics and publications of other similar Research Bodies as issued.

IN considering the size of wings, which aero‐plane designers require to lift a given weight, the fact is very apparent that lifting surfaces have become smaller as the art of aeroplane design has advanced. Fig. 1 shows the trend of this development from pre‐war days up to now, expressed by a steady increase in wing loading (lb. per sq. ft.). How is this development likely to go on, and where will it end ?

TO deliver a lecture in commemoration of the Wright Brothers before the Institute of Aeronautical Sciences is a great honour of which I am deeply aware: this honour one feels is due not solely to the technical situation but to somemore subtle link between the Institute and the Royal Aeronautical Society and our two countries.

THE Rainbow is the commercial adaptation of the XF‐12 photographic aeroplane the Republic Aviation Corporation completed for the Army Air Forces. In 1943, the Photographic Section of the A.A.F. issued specifications for a new multi‐engined, long‐range, high‐speed, reconnaissance aeroplane to fly at very high altitudes. The required performance was so much beyond anything in existence at the time that it posed a real problem to designers of high performance aeroplanes. Republic engineers, who for years had specialized in high‐altitude, high‐speed pursuit planes, eagerly accepted the challenge. After exhaustive studies it was found that the performance required by the specification could only be met with a four‐engined machine using Pratt and Whitney R‐4360 engines, supercharged to carry full military power to 40,000 ft. Other combinations would either fail in speed, or in range, or in desired rate of climb or ceiling. A proposal based on four 4360 engines was submitted to the A.A.F., and in March 1944, the Company was awarded a contract for two XF‐12 aircraft. The first prototype was completed in December, 1945, and made its first flight on February 4, 1946.