Flight operations for higher harmonic control research.

72 Pages·0.86 MB·en_US

by  McGovern, James Joseph.;Wood, E. Roberts.

NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
FLIGHT OPERATIONS
FOR
HIGHER HARMONIC CONTROL RESEARCH
by
James Joseph McGovern
March, 1991
Thesis Advisor: E. Roberts Wood
Approved for public release; distribution is unlimited.
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FLIGHT OPERATIONS FOR HIGHER HARMONIC CONTROL RESEARCH (U)
PERSONAL AUTHOR(S)
!McGovern, James J.
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SUPPLEMENTARY NOTATION
>
The views expressed in this thesis are those of the author and do not reflect the
official policy or position of the Defense Department or the U.S. Government.
COSATI CODES 18 SUBJECT TERMS {Continue on reverse if necessary and identify by block number)
FIELD GROUP SUB-GROUP
HHC, RPH, Flight Operations, Vibrations, Flight Test
) ABSTRACT {Continue on reverse if necessary and identify by block number)
The Department ofAeronautics and Astronautics at the Naval Postgraduate School (NFS) is interested
in extending the useful life of Naval helicopters. Recognizing the need to reduce vibrations caused by
aerodynamic loads on the rotor system, a Higher Harmonic Control (HHC) research effort has begun. The test
HHC
vehicle of the system is a Remotely Piloted Helicopter (RPH). This thesis contains an overview of the
NPS HHC research effort includingbasic helicopter dynamics, HHC theory, and establishes research milestones.
An RPH flight operations program was developed that included the first flights oftwo out ofthree RPH's being
used in the research effort, identification of data and data acquisition requirements, and initial hover vibration
tests. The vibration tests produced data oflimited value. The two bladcd RPH tested appears to produce peak
accelerations at roughly twice the main rotor speed. This indicates that like a full scale helicopter, the largest
vibrations do enter the airframe through the rotor system and are not a result of engine vibrations. Hence,
RPH's are suitable for HHC research. This effort completed one portion of the long term HHC research and
HHC
can lead to the practical and safe testing of a fully functioning system.
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Flight Operations
For
Higher Harmonic Control Research
by
James Joseph McGovern
Lieutenant, United States Navy
B.S., United States Naval Academy, 1983
Submitted in partial fulfillment
of the requirements for the degree of
MASTER OF SCIENCE IN AERONAUTICAL ENGINEERING
from the
NAVAL POSTGRADUATE SCHOOL
March 1991
ABSTRACT
The Department of Aeronautics and Astronautics at the Naval Postgraduate
School (NPS) is interested in extending the useful life of Naval helicopters.
Recognizing the need to reduce vibrations caused by aerodynamic loads on the rotor
system, a Higher Harmonic Control (HHC) research effort has begun. The test
HHC
vehicle of the system is a Remotely Piloted Helicopter (RPH). This thesis
contains an overview of the NPS HHC research effort including basic helicopter
dynamics, HHC theory, and establishes research milestones. An RPH flight
operations program was developed that included the first flights of two out of three
RPH's being used in the research effort, identification of data and data acquisition
requirements, and initial hover vibration tests. The vibration tests produced data of
limited value. The two bladed RPH tested appears to produce peak accelerations
at roughly twice the main rotor speed. This indicates that like a full scale helicopter,
the largest vibrations do enter the airframe through the rotor system and are not a
HHC
result of engine vibrations. Hence, RPH's are suitable for research. This
HHC
effort completed one portion of the long term research and can lead to the
HHC
practical and safe testing of a fully functioning system.
in
TABLE OF CONTENTS
BACKGROUND
I. 1
A. HELICOPTER VIBRATION
1
VIBRATION REDUCTION
B. 3
1. Passive Techniques 3
2. Active Techniques 5
SCOPE
II. 7
HIGHER HARMONIC CONTROL
III. 8
HELICOPTER DYNAMICS
A. 8
HHC THEORY
B. 11
HHC RESEARCH EFFORT
C. 13
1. Goals 13
HHC
2. Flight Testing 15
3. Remotely Piloted Helicopters 15
RPH
4. Support Facilities 15
5. Data Gathering 17
IV