In the present paper, the preliminary design methodology for helicopters developed at Mil Design Bureau and further modified at the Moscow Aviation Institute and at the University of Maryland is presented and used to determine the basic geometric and weight characteristics of transport helicopters based on the required payload and range. Using these inputs, the take-oft weight, main rotor geometry, payload/range, direct operating cost, and other characteristics are determined. Results have been presented for four values of the payload: 4, 10 and 20 metric tons. The results show that for each value of payload, there is an optimum disk loading, the value of which depends on the number of blades and the aspect ratio of the main rotor blades. The concept of vehicle energy efficiency (defined as the specific range per unit weight of fuel consumed) enables comparison of different helicopters. The predictions with the Mil preliminary design method compare well with the actual values of main rotor diameter, weight efficiency, and payload-range diagram for Russian and Western helicopters. The results given in the present paper are a first approximation and can be useful in the selection of preliminary configurations for a given payload and range, and in the evaluation of performance and economics of the designs. For more accurate results, it is important to carry out more detailed studies including the following variables: 1) Carriage of cargo: internal or external. 2) Incorporation of the varying values of lift-to-drag ratio vs. disk loading and propulsive efficiency coefficient vs. relative flight speed. 3) More detailed weight calculations using detailed specifications.
Preliminary design of transport helicopters
Vorläufiger Entwurf von Transporthubschraubern
Journal of the American Helicopter Society ; 48 , 2 ; 71-79
2003
9 Seiten, 5 Bilder, 3 Tabellen, 8 Quellen
Aufsatz (Zeitschrift)
Englisch
Preliminary Design of Transport Helicopters
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