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naca-report-993

naca-report-993
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  • 1.43 MB File Size
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  • September 1, 2016 Create Date
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National Advisory Committee for Aeronautics, Report - An Introduction to the Physical Aspects of Helicopter Stability

naca-report-993 An Introduction to the Physical Aspects of Helicopter Stability-1

In order to provide engineers interested in rotating-wing air-
craft but with no specialized training in stability theory some
understanding of the factors that influence the flying qualities
of the helicopter, an explanation is made of both the static
stability and the sticlcgixed oscillation in horering and forward
flight in terms of fundamental physical quantities. Three
significant stability factors—static stability with angle of attack,
static stability with speed, and damping due to a. pitching or
rolling velocity—are explained in detail.

Most of the published literature on helicopter stability is
written for the specialist in stability theory and is somewhat
difficult for the average engineer to understand. An
explanation of the fundamental ideas underlying helicopter
stability in terms of the basic physical parameters involved
rather than in specialized mathematics therefore appears
desirable.

The subject is introduced by discussions of the means of
helicopter control and the origin of the forces and moments
which act on the helicopter as a result of deviations from
trimmed flight conditions. These fundamental ideas are
then applied to the hovering helicopter and to the helicopter
in forward flight. An understanding of the stability of the
helicopter in both of these conditions is aided by analogy with
the stability of the fixed—wing airplane. This comparison
is made possible in hovering because of the fact. that the zero
lateral velocity of the trimmed airplane in forward flight is
analogous to zero translational velocity of the hovering
helicopter. In forward flight, helicopter longitudinal sta-
bility may be directly compared with the corresponding
motions of the airplane.

The handling qualities of an aircraft are those stability and
control characteristics that affect the ease and safety of flying
the aircraft. This report. is primarily restricted to a study
of helicopter stability which, aside from its direct efi'ect on
handling qualities, must- also be studied in order to under-
stand control characteristics. Thevfirst phase of stability
considered is static stability, which has an obvious influence
on the handling qualities of the helicopter.

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naca-report-993

naca-report-993
  • Version
  • 124 Downloads
  • 1.43 MB File Size
  • 1 File Count
  • September 1, 2016 Create Date
  • September 1, 2016 Last Updated
Scroll for Details

National Advisory Committee for Aeronautics, Report - An Introduction to the Physical Aspects of Helicopter Stability

naca-report-993 An Introduction to the Physical Aspects of Helicopter Stability-1

In order to provide engineers interested in rotating-wing air-
craft but with no specialized training in stability theory some
understanding of the factors that influence the flying qualities
of the helicopter, an explanation is made of both the static
stability and the sticlcgixed oscillation in horering and forward
flight in terms of fundamental physical quantities. Three
significant stability factors—static stability with angle of attack,
static stability with speed, and damping due to a. pitching or
rolling velocity—are explained in detail.

Most of the published literature on helicopter stability is
written for the specialist in stability theory and is somewhat
difficult for the average engineer to understand. An
explanation of the fundamental ideas underlying helicopter
stability in terms of the basic physical parameters involved
rather than in specialized mathematics therefore appears
desirable.

The subject is introduced by discussions of the means of
helicopter control and the origin of the forces and moments
which act on the helicopter as a result of deviations from
trimmed flight conditions. These fundamental ideas are
then applied to the hovering helicopter and to the helicopter
in forward flight. An understanding of the stability of the
helicopter in both of these conditions is aided by analogy with
the stability of the fixed—wing airplane. This comparison
is made possible in hovering because of the fact. that the zero
lateral velocity of the trimmed airplane in forward flight is
analogous to zero translational velocity of the hovering
helicopter. In forward flight, helicopter longitudinal sta-
bility may be directly compared with the corresponding
motions of the airplane.

The handling qualities of an aircraft are those stability and
control characteristics that affect the ease and safety of flying
the aircraft. This report. is primarily restricted to a study
of helicopter stability which, aside from its direct efi'ect on
handling qualities, must- also be studied in order to under-
stand control characteristics. Thevfirst phase of stability
considered is static stability, which has an obvious influence
on the handling qualities of the helicopter.

FileAction
naca-report-993 An Introduction to the Physical Aspects of Helicopter Stability.pdfDownload 
17,005 Documents in our Technical Library
2449614 Total Downloads

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Newest Additions

NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
NASA-RP-1060 Subsonic Aircraft: Evolution and the Matching of Size to Performance
AA-CP-20212-001
AA-CP-20212-001
ADPO10769 Occurrence of Corrosion in Airframes
The purpose of this lecture is to provide an overview ...
MIL-STD-1759 Rivets and Rivet Type Fasteners Preferred for Design
The purpose of this book form standard is to provide ...
MIL-STD-810G Environmental Engineering Considerations and Laboratory Tests
This standard contains materiel acquisition program planning and engineering direction ...