Steady and Unsteady Hover Test of a Lift Compounding Rotorcraft

Abstract

Compound rotorcraft can be a viable option to achieve moderately high speeds of 240 knots. However, there is no systematic wind tunnel test data in the public domain to understand the complex interactional aeromechanics involved. This work is part of a test campaign to conduct multiple high-speed wind tunnel tests of various compound configurations. The compound configuration consists of a single main rotor, a single wing on the retreating side for lift augmentation, and a single rear propeller for propulsive augmentation. In this paper, hover test results are presented. Hover tests were conducted for various configurations and at different tip Mach numbers with the maximum value of 0.5. Rotor and wing performances are measured separately using individual balances. Rotor blades are equipped with strain gauges for measuring flap, lag, and torsional moments at [Formula: see text] radial stations. The wing location is [Formula: see text] below the main rotor, and the measured wing download is only 2.8% of the rotor thrust. The wing provides a partial ground effect, making the rotor more efficient and almost compensates for the download with less than 1% reduction in net figure of merit. Blade structural loads correlate satisfactorily between the analysis and measurement except for lag bending moment. This discrepancy is a large 2/rev lag bending moment measured in the test, which needs further investigation. Propeller hover test was conducted up to 2500 revolutions per minute (tip Mach number of 0.25) at a single collective. Prediction correlates well and captures the low-Reynolds-number effect for lower revolutions per minute.

Comparison of Size and Performance of Small Vertical and Short Takeoff and Landing UAS

“…Past survey articles of UAS systems include [5], [6]. Work in [7][8][9][10] encompasses larger aircraft and discusses empirical correlations between aircraft parameters, such as size, weight, wing and tail geometries, and propulsion. Reference [9] focuses on rotorcraft and suggests empirical scaling laws and characterizes variation in battery characteristics among platforms.…”

“…Work in [7][8][9][10] encompasses larger aircraft and discusses empirical correlations between aircraft parameters, such as size, weight, wing and tail geometries, and propulsion. Reference [9] focuses on rotorcraft and suggests empirical scaling laws and characterizes variation in battery characteristics among platforms. The authors in [11,12] perform similar studies on small fixed-wing, rotarywing, and hybrid UAS that include analysis of datalink range, altitude, endurance, size and weight.…”