Multiple metrics are applied to the design of a large civil tiItrotor, integrating minimum cost and minimum environmental impact. The design mission is passenger transport with similar range and capacity to a regional jet. Separate aircraft designs are gener ated for minimum empty weight, fuel burn, and environmental impact. A metric specifically developed for the design of aircraft is employed...

To address the question of the role of nonlinear effects in the propagation of noise radiated by high-power jet aircraft, extensive measurements were made of the F-22A Raptor during static engine run-ups. Data were acquired at low-, intermediate-, and high-thrust engine settings with microphones located 23-305 m from the aircraft along several angles. Comparisons between the results of a genera...

Aircraft design is a highly nonlinear problem and inherently multidisciplinary activity that involves a large number of design variables and different models and tools for various aspects of design. A spreadsheet based genetic algorithm (GA) approach is presented to optimize the preliminary design of an aircraft. A domain independent general purpose genetic algorithm is proposed to implement th...

Hole-punch and canal clouds have been observed for more than 50 years, but the mechanisms of formation, development, duration, and thus the extent of their effect have largely been ignored. The holes have been associated with inadvertent seeding of clouds with ice particles generated by aircraft, produced through spontaneous freezing of cloud droplets in air cooled as it flows around aircraft p...

Crackle, the impulsive quality sometimes present in supersonic jet noise, has traditionally been defined in terms of the pressure waveform skewness. However, recent work has shown that the pressure waveform time derivative is a better quantifier of the acoustic shocks believed to be responsible for its perception. This paper discusses two definitions of crackle, waveform asymmetry versus shock ...

The paper develops the argument that the long-term structural evolution of an industry depends on the evolution of a vertically-related, downstream industry. We analyse two pairs of vertically-related industries, the jet and turboprop aircraft and engine industries, since the first introduction of the jet and turboprop technologies to 1998. The paper shows that the evolutionary dynamics of the ...

The paper develops the argument that the long-term structural evolution of an industry depends on the evolution of a vertically-related, downstream industry. We analyse two pairs of vertically-related industries, the jet and turboprop aircraft and engine industries, since the first introduction of the jet and turboprop technologies to 1998. The paper shows that the evolutionary dynamics of the ...