Flight tests on hingeless rotor compound helicopter to determine level flight and maneuvering characteristics

Roche, Julian MSAE, Embry-Riddle Aeronautical University, December 2015. Aerodynamic Trade Study of Compound Helicopter Concepts. The relative performance attributes of compound helicopter concepts have been examined, including their potential for meeting the requirements of several challenging mission profiles. For each concept, which included lift and/or propulsive compounding, a suite of aerodynamic performance models was developed using energy methods. In the case of a lift-compounded concept, an aerodynamic model representing the force interaction effects of the main rotor wake with the wing was also developed. Models of a conventional helicopter and of a tiltrotor were implemented as well, and the results used as a datum for comparison. In each case, the predictive capabilities of the model were validated using flight test data. The comparisons were conducted on the basis of equal aircraft gross weight and also on the basis of equal useful load. The performance of each rotorcraft was then assessed in terms of key attributes, including maximum attainable airspeed, flight efficiency (liftto-drag ratio), along with the anticipated flight range and endurance. Parametric studies on the compound helicopter concepts were conducted to explore the relative advantages of adding a wing (including the effects of span and aspect ratio) and of the propulsive system (i.e., thrust augmentation). In general, it was found that a pure lift compounded helicopter concept did not offer improvements in capabilities over a conventional helicopter. However, both lift and propulsive compounding used together were shown to significantly improve the flight capabilities over a conventional

background or methods

/pdf/aerodynamic-trade-study-of-compound-helicopter-concepts-261cvkoa6l.pdf

Investigation of level-flight and maneuvering characteristics of a hingeless-rotor compound helicopter

Aerodynamic Trade Study of Compound Helicopter Concepts

Use of Thrust and Lift Augmentation for Increasing Helicopter Operating Speed

/pdf/effectiveness-of-the-compound-helicopter-configuration-in-1uv1w8dz3n.pdf

Effectiveness of the Compound Helicopter Configuration in Rotorcraft Performance Increase

/pdf/investigation-of-level-flight-and-maneuvering-2ozdmv39sb.pdf

: The report presents the results of a speed extension program on the compound version of the rigid-rotor XH-51A helicopter. The principle objective of the program was to investigate the flight characteristics of the compound helicopter with special emphasis on the areas of flying qualities, performance, structural loads, vibration, and maneuverability in the speed range of 200 to 230 knots true airspeed. All contract objectives were met or exceeded. The maximum level flight true airspeeds demonstrated, during this program, were 236 knots at sea level and 228 knots at a density altitude of 12,000 feet.

http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0627372&Location=U2&doc=GetTRDoc.pdf

Extension of the high-speed flight envelope of the xh-51a compound helicopter

: Analytical methods are presented for determining the dynamic stability and control characteristics of generalized procedures which are considerably simplified through the extensive use of information presented in graphs and charts. These charts are applicable to flight conditions from hover to high forward speeds. The charts for low forward speeds were obtained from the rotor performance data based on classical rotor theory. However, the high- speed charts exclude the major assumptions of classical theory and include blade compressibility, stall, reverse flow, large inflow ratios, etc. The handbook contains information suitable for extensive digital and analog computer studies and also provides rapid procedures for predicting helicopter stability and control characteristics for preliminary design applications.

Investigation of level-flight and maneuvering characteristics of a hingeless-rotor compound helicopter

Citations

Aerodynamic Trade Study of Compound Helicopter Concepts

Use of Thrust and Lift Augmentation for Increasing Helicopter Operating Speed

Effectiveness of the Compound Helicopter Configuration in Rotorcraft Performance Increase

References

Extension of the high-speed flight envelope of the xh-51a compound helicopter

Stability and control handbook for helicopters

Use of Thrust and Lift Augmentation for Increasing Helicopter Operating Speed

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