Analysis of VSTOL aircraft configurations for short haul air transportation systems
Author(s)Gallant, Robert A.; Scully, M.; Lange, William Richard.
Analysis of Vertical and/or Short Take-Off and Landing aircraft configurations for short haul air transportation systems
United States. Dept. of Commerce
Massachusetts Institute of Technology. Flight Transportation Laboratory
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Introduction: The potential of air transportation as a means of filling the growing need for a mass short haul transportation system was investigated in Ref. 1 where all aspects of short haul air transportation systems were examined in some detail. It was concluded that air transportation could provide a promising means of relieving the congestion associated with the heavy vehicular ground traffic encountered on our urban access routes and at a cost which could well be competitive in the 1970 period with surface transportation systems. This conclusion was postulated on the basis of existing developments in the aircraft industry not yet put into practice on operating airlines but whose feasibility has been well demonstrated with experimental units. Among the many aspects of the total system which must be examined in arriving at such a conclusion are the flight vehicle characteristics. The direct operating costs (DOC) of these vehicles was chosen as a measure of their effectiveness. In short haul operations the direct costs are frequently less important than indirect costs in determining total transportation costs and hence ticket price. However the DOC is a convenient measure for estimating the relative performance of different vehicle configurations and of the penalties associated with operation off optimum conditions. Furthermore, the previous study (Ref. 1) had quantified the almost obvious need in short haul transportation for a vehicle capable of operating from highly congested areas and requiring a minimum in take-off, landing or cleared approach areas. This need directed attention to the newer concepts of vertical take-off and landing (VTOL) aircraft which would not have the speed limitation of present day helicopters, the only VTOL aircraft currently in commercial operations. Because present day experience with these aircraft indicates their direct operating costs to be several times that of comparable fixed wing aircraft, there has been a natural reluctance to predict future operating costs for these vehicles at a level which would make them effective other than in a high-priced specialized operation such as an airline feeder system. Consequently, in Ref. (1), a study of the costs and operating procedures of the existing helicopter airlines was conducted in some depth and by this means the predicted direct operating costs were removed from the realm of discussion and opinion and reduced to a matter of statistics and analysis. Maintenance costs and lost time in air and ground maneuvering were, as expected, important aspects of the cost problem and these were therefore analyzed on a quantitative basis. While there may still be room for disagreement on the predicted DOC for the various vehicles considered in this study, the quantitative information on which these are based have been carefully documented in Ref. (1) and are further substantiated in Ref. (2) for the maintenance aspects and in this report for the vehicle characteristics such as weight, fuel burned and block speeds. This additional documentation has been considered desirable not only to confirm the previous results and to explore other promising configurations, but also to provide a basis for rational discussion of the relative merits and potentials of different vehicle configurations which all too often in the past has been conducted on a subjective rather than an objective basis. -3- It may be well to reiterate the conclusion of Ref. (1) that, in face of the high indirect costs inherent in short haul systems, the actual vehicle configuration is not a dominant factor in determining total operating costs. Any well engineered configuration capable of safe all weather operations would probably prove satisfactory. However the need for direct access to city centers with a minimum of land taking does indicate the desirability of VTOL. These vehicles have the potential for appreciably reducing block times, and hence costs, in the shorter legs, below 50 miles, of interest in intra urban or suburban travel, providing present concepts of control and navigation currently under intensive development for military applications can be reduced to practice in the more legalistic environment of commercial operations.
November 1966PB-174912Includes bibliographical references
[Cambridge, Mass.] : Massachusetts Institute of Technology, Flight Transportation Laboratory, 
FTL report (Massachusetts Institute of Technology. Flight Transportation Laboratory) ; R66-1
Vertically rising aircraft, Design and construction