Generalized maximum specific range performance
| Autor: | Egbert Torenbeek, Hans Wittenberg |
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| Rok vydání: | 1983 |
| Předmět: | |
| Zdroj: | Journal of Aircraft. 20:617-622 |
| ISSN: | 1533-3868 0021-8669 |
| DOI: | 10.2514/3.44920 |
| Popis: | Generalized criteria for optimum cruise (point) performance in quasisteady flight are derived for jet and propeller aircraft, using logarithmic differentiation. The derivation is valid not only for low speeds, but also for Mach numbers where compressibility effects are present; and it is not based on the usual assumption of constant TSFC or constant overall powerplant efficiency. Optimum conditions are obtained for the unconstrained variation of altitude and Mach number and for the case where constraints are imposed on W/b or 776. The resulting criteria define the relationships between the logarithmic partial derivatives of CD with respect to CL and M and of the overall powerplant efficiency with respect to M and the engine rating (thrust). Special conditions are considered, indicating that simple solutions can be given, e.g., for the optimum drag rise dC^/dM and for aircraft with parabolic drag polars. The relationship with classical criteria for optimum long-range flight are also shown, and a numerical example for a high-subsonic jet transport illustrates a practical computational procedure. The present method is useful in the preliminary design phase, but may be used for on-board calculation of optimum flight conditions as well. |
| Databáze: | OpenAIRE |
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