Some Economic Aspects of Transport Airplane Performance. Parts II and III

Abstract

Block speed is the only airplane performance characteristic appearing directly in the cost equations. It can be defined as the distance from terminal to terminal divided by the time from passenger station to passenger station. An accurate determination of block speed requires the computation of climb, level and descent distances and times as well as the arbitrary establishment of a terminal maneuvering and taxi time. For purposes of simplification in this study the following assumptions are made: (a) flight altitude— 14,000 feet; (b) terminal altitudes—sea level; (c) wind velocity—zero; (d) net time lost in climb and descent—0.06 hour; (e) taxi and maneuvering time —0.20 hour. In order to account for inaccuracies in flying, necessary deviations from true course and other contingencies it is further assumed in the computation of block time that the distance is increased 2 per cent. Based on the above assumptions, the equation for block speed can be expressed as type closely approximates transport airplanes now under construction. Three basic airplanes differing from each other only in the value selected for / (which is defined as the flatplate area of unity drag coefficient equivalent to minimum profile and parasite drag) are assumed. These basic airplanes are further assumed to have certain characteristics in common, as given in Table 3.