WorldCat Identities

Berry, John D.

Works: 3 works in 17 publications in 1 language and 592 library holdings
Roles: Author
Classifications: TL716,
Publication Timeline
Most widely held works by John D Berry
Description of the U.S. Army small-scale 2-meter rotor test system by Arthur E Phelps( Book )

6 editions published in 1987 in English and held by 139 WorldCat member libraries worldwide

A small scale powered rotor model was designed for use as a research tool in the exploratory testing of rotors and helicopter models. The model, which consists of a 29 hp rotor drive system, a four blade fully articulated rotor, and a fuselage, was designed to be simple to operate and maintain in wind tunnels of moderate size and complexity. Two six-component strain-gauge balances are used to provide independent measurement of the rotor and fuselage aerodynamic loads. Commercially available standardized hardware and equipment were used to the maximum extent possible, and specialized parts were design so that they could be fabricated by normal methods without using highly specialized tooling. The model was used in a hover test of three rotors having different planforms and in a forward flight investigation of a 21 percent scale model of a U.S. Army scout helicopter equipped with a mast mounted sight. Keywords: Rotor model; Hover testing; Rotor scaling
Unsteady velocity measurements taken behind a model helicopter rotor hub in forward flight by John D Berry( Book )

6 editions published in 1997 in English and held by 126 WorldCat member libraries worldwide

Drag caused by separated flow behind the hub of a helicopter has an adverse effect on aerodynamic performance of the aircraft. To determine the effect of separated flow on a configuration used extensively for helicopter aerodynamic investigations, an experiment was conducted using a laser velocimeter to measure velocities in the wake of a model helicopter hub operating at Mach-scaled conditions in forward flight. Velocity measurements were taken using a laser velocimeter with components in the vertical and downstream directions. Measurements were taken at 1 3 stations downstream from the rotor hub. At each station, measurements were taken in both a horizontal and vertical row of locations. These measurements were analyzed for harmonic content based on the rotor period of revolution. After accounting for these periodic velocities, the remaining unsteady velocities were treated as turbulence. Turbulence intensity distributions are presented. Average turbulent intensities ranged from approximately 2 percent of free stream to over 15 percent of free stream at specific locations and azimuths. The maximum average value of turbulence was located near the rear-facing region of the fuselage
Wind-Tunnel Evaluation of a 21 Percent-Scale Powered Model of a Prototype Advanced Scout Helicopter( Book )

2 editions published in 1985 in English and held by 1 WorldCat member library worldwide

This exploratory wind-tunnel investigation was conducted in the Langley 4- by 7- Meter Tunnel. The investigation was conducted to define the overall aerodynamic characteristics of the Army Helicopter Improvement Program (AHIP), to determine the effects of the rotor on the aerodynamic characteristics, and to evaluate the effect of a mast-mounted sight on the aircraft stability characteristics. Tests covered a range of thrust coefficients, advance ratios, angles of attack, and angles of sideslip and were run for both rotor-on and rotor-off configurations. Results of the investigation showed that the prototype configuration was longitudinally unstable with angle of attack for all configurations tested. The instability was due to unfavorable interference effects between the horizontal tail and the wake shed from the engine pylon and rotor hub, which caused a loss of horizontal-tail effectiveness. The addition of the mast-mounted sight had little effect on the stability of the model, but it caused an alteration in the rotor lift distribution that resulted in substantial interference drag for the sight. Keywords: Scout helicopter; Mast-mounted sight; Powered rotor testing; Rotor interference effects
Audience Level
Audience Level
  Kids General Special  
Audience level: 0.56 (from 0.51 for Unsteady v ... to 0.98 for Wind-Tunne ...)

English (14)