This is the HTML version of a paper presented at:
The American Helicopter Society International Specialists' Meeting, Stratford, Connecticut, October 11-13, 1995.
Description of the Experiment
The experimental set-up consisted of the rotor and a generic body shape. This set-up has been used previously at the University of Maryland (Ref. 16), and is an AGARD test case for rotor/airframe interaction modeling (see Ref. 17) In the present experiments, a T-tail empennage was located on the tail boom 1.131 m (44.5 in) behind the rotor hub, as illustrated in Fig. 1. The tail was supported by a structure inside the tailboom, and for some tests was connected to a separate strain-gage balance. The rotor had a fully articulated hub with four blades, and a conventional swashplate arrangement. The rotor diameter was 1.65 m (65 in), and the blades were tapered in planform with a taper ratio of 3:1 over the outermost 6 % of the blade, with 13 degrees of nose-down linear twist.
Figure 1: Sketch of the rotor/body/empennage system, high tail position
The T-tail geometry used for the present studies comprised a horizontal stabilizer with a constant chord of 0.203 m (8.0 in), connected to the tail boom by an aerodynamic fairing of the same chord. The horizontal stabilizer could be located at two vertical positions, namely z_h/R = +0.022 for the high tail configuration, and z_h/R = -0.055 for the low tail configuration. These configurations simulated most of the aerodynamic conditions likely to be encountered by a horizontal stabilizer on a typical helicopter. The horizontal stabilizer employed a NACA 0012 airfoil, with an aspect ratio of 2.5. The stabilizer was mounted at zero degrees angle of attack relative to the longitudinal axis of the body.
A summary of the main characteristics of the rotor, fuselage, and tail assembly is given in Table 1, with a photograph of the setup in Figure 2.
| Number of blades | 4 |
| Rotor radius | 0.826 m (32.5 in) |
| Rotor blade chord | 63.5 mm (2.5 in) |
| Rotor solidity | 0.098 |
| Blade twist (linear) | -13° |
| Blade airfoil | NACA RC310/410 |
| Fuselage length | 1.943 m (76.5 in) |
| Fuselage max. diameter | 0.254 m (10.0 in) |
| Stabilizer aspect ratio | 2.5 |
| Stabilizer chord | 0.203 m (8.0 in) |
| Stabilizer airfoil section | NACA 001 |
| High tail position, z_h/R | +0.022 |
| Low tail position, z_h/R | -0.055 |
Table 1: Main characteristics of the rotor, fuselage, and stabilizer models
Figure 2: Photograph of the rotor/body/empennage set-up in the wind tunnel
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