Masters Theses

Date of Award

12-1990

Degree Type

Thesis

Degree Name

Master of Science

Major

Aviation Systems

Major Professor

U. Peter Solies

Committee Members

Robert B. Richards, Ralph A. Kimberlin

Abstract

With the current trend towards reduction in defense appropriations for research and development of military aircraft, utilizing existing, off the shelf, military or commercial helicopters is an alternative solution. The first part of this treatise presents an evaluation of a commercial helicopter, the production model BK-117A-3, for use as a light attack, utility and medical evacuation vehicle. Flight test data were collected during four flights totaling 6 hours, while 4 hours of ground evaluation was conducted. Six serious deficiencies were discovered which must be corrected prior to military use of the aircraft. These serious deficiencies included the following: a severely limited sideslope landing capability; random yaw oscillations; restricted field of view; the adverse position and operation of the cyclic lock mechanism; inadequate hover, level flight and vertical climb performance; and severe vibrations. In addition there were several significant and annoying deficiencies documented that should be corrected but would not prevent the effective use of the aircraft. This treatise also presents possible solutions to many of the deficiencies discovered and their effect on performance and flying qualities utilizing currently available technology as follows: installation of the Light Helicopter Technology (LHTEC) T-800 engine; incorporation of an improved automatic flight control system (AFCS) in the yaw axis; use of the British Experimental Rotor Program (BERP) blade design developed by Westland Industries in conjunction with a hingeless rotor head developed by Messerschmitt-Bolkow-Blohm (MBB) Helicopter Corporation; retrofit with swiveling skid type undercarriage; installation of a mast mounted sight; reconfiguration with a composite aerodynamically refined airframe fuselage; retrofit with an MBB designed fiber-elastomeric tail rotor; and utilization of various vibration isolation techniques. The BK-117A-3 helicopter demonstrated satisfactory potential during the flight and ground tests in its commercial configuration. Upon correction of the serious deficiencies via the proposals contained in this treatise, it will be satisfactory for military use.

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