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02 AERODYNAMICS
several connotations. To name a few: technological obsolescence,
the spectre of runaway maintenance costs, and safety. Moreover,
spare parts, processes and tooling may no longer be available,
logistic procedures may have changed and suppliers may be out of
the business. Budgetary limitations and higher fleet utilisation will
increase the demand to cope with aging structures and major
subsystems like engines and avionics. Specific topics covered by
this Lecture Series are: 1) Aircraft Loads; 2) Aging Systems and
Sustainment Technology; 3) SNECMA ATAR Engines 1960-2020.
Smarter Ideas and Less Money; 4) Repair Options for Airframes; 5)
Risk Assessments of Aging Aircraft; 6) Occurrence of Corrosion in
Airframes; 7) Human Factors in Aircraft Maintenance; 8) Extension of
the Usable Engine Life by Modelling and Monitoring; 9) Loads
Monitoring and HUMS; 10) Depot Level Maintenance of U.S. Aircraft
Engines in NATO Air Forces. Role of Private Industry and Procedures
with U.S. and European Air Forces; 11) Prevention and Control
in Corrosion; 12) Safety and Service Difficulty Reporting; 13) Tutorial
on Repair Software; 14) Inspection Technologies; 15) Inspection
Reliability and Human Factors; 16) Material and Process Technology
Transition to Aging Aircraft
Derived from text
Aircraft Maintenance; Aging (Materials); Commercial Aircraft;
Aircraft Structures; Airline Operations
20010028480 R-Tec, Rolling Hills Estates, CA USA
REPAIR OPTIONS FOR AIRFRAMES
Ratwani, Mohan M., R-Tec, USA; Aging Aircraft Fleets: Structural
and Other Subsystem Aspects; March 2001, pp. 4-1 - 4-19; In
English; See also 20010028476; Original contains color illustrations;
Copyright Waived; Avail: CASI; A03, Hardcopy
Maintaining the airworthiness of in-service aircraft and at the
same time keeping the maintenance cost low is of prime concern to
the operators and regulatory authorities. In order to keep maintenance
cost low, right decisions need to be made regarding replacing
or repairing the in-service damaged components. The choice between
replacing or repairing a structural component is governed by
a number of factors such as the availability of spares, duration a
structural component is expected to be in service, feasibility of repair,
repair meeting structural integrity requirements, and inspection requirements
for the repair. If it is economical to repair the component
then the optimum repair design needs to be selected. This paper
discusses structural life enhancement techniques along with the
state-of-practice methods of repairing metallic and composite structures.
Applications of advanced repair methods such as composite
patch repair of cracked metallic structures are discussed. Available
computer codes for designing repairs are briefly described.
Derived from text
Airframes; Maintenance; Low Cost; Inspection; Structural Failure;
Aircraft Reliability
20010067671 Research and Technology Organization, Applied
Vehicle Technology Panel, Neuilly-sur-Seine, France
ACTIVE CONTROL TECHNOLOGY FOR ENHANCED PERFOR-
MANCE OPERATIONAL CAPABILITIES OF MILITARY AIR-
CRAFT, LAND VEHICLES AND SEA VEHICLES
June 2001; 950p; In English; In French; 8-11 May 2000, Brunswick,
Germany; See also 20010067672 through 20010067754; CD-ROM
contains full text document in PDF format; Original contains color
illustrations
Report No.(s): RTO-MP-051; AC/323(AVT-048)TP/35; ISBN 92-
837-0018-X; Copyright Waived; Avail: CASI; C01, CD-ROM; A99,
Hardcopy; A10, Microfiche
The Symposium analyzed the potential of active control technology
for the performance demands of future vehicles and engines.
in particular high maneuverability, lower specific fuel consumption,
higher power-to-weight ratios, and lower life-cycle cost. Performance,
stability, control, fluid dynamics, structural and engine layout
questions were dealt with in five keynotes and 77 papers. The
following sessions were held: Boundary Layer Control; Active Flow
Control of Nozzle/Jet; Drag and Buffet Control; Noise Control; Vortex
Control; Flight Vehicle Active Control; Smart Structures Applications;
Active Control Technology For Load Alleviation; Active Elements for
Structural Design; Active Materials and Applications; Applications
Overview; Compressor Stall/Surge Measurements; Compressor
Stall/Surge Control; Combustion Instabilities, Measurements and
Predictions; Combustion Instabilities, Control Fundamentals; and
Combustion Instabilities, Control Applications. The Symposium was
4
organized by the Applied Vehicle Technology Panel (AVT).
Author
Active Control; Flight Control; Conferences; Boundary Layer
Control; Fluid Dynamics; Thrust Vector Control; Buffeting;
Combustion Control; Combustion Stability; Aerodynamic Stability
02
AERODYNAMICS
19990032465 NASA Langley Research Center, Hampton, VA USA
AERODYNAMIC PARAMETERS OF HIGH PERFORMANCE AIR-
CRAFT ESTIMATED FROM WIND TUNNEL AND FLIGHT TEST
DATA
Klein, Vladislav, George Washington Univ., USA; Murphy, Patrick C.,
NASA Langley Research Center, USA; System Identification for
Integrated Aircraft Development and Flight Testing; March 1999, pp.
18-1 - 18-20; In English; See also 19990032449; Copyright Waived;
Avail: CASI; A03, Hardcopy; A04, Microfiche
A concept of system identification applied to high performance
aircraft is introduced followed by a discussion on the identification
methodology. Special emphasis is given to model postulation using
time invariant and time dependent aerodynamic parameters, model
structure determination and parameter estimation using ordinary
least squares and mixed estimation methods. At the same time
problems of data collinearity detection and its assessment are
discussed. These parts of methodology are demonstrated in examples
using flight data of the X-29A and X-31A aircraft. In the third
example wind tunnel oscillatory data of the F-16XL model are used.
A strong dependence of these data on frequency led to the development
of models with unsteady aerodynamic terms in the form of
indicial functions. The paper is completed by concluding remarks.
Author
System Identification; Unsteady Aerodynamics; Supersonic Aircraft;
Fighter Aircraft; Mathematical Models; Aircraft Design; Aerodynamic
Characteristics
19990032471 Georgia Inst. of Tech., School of Aerospace
Engineering, Atlanta, GA USA
STUDY OF A ROTOR FLAP-INFLOW MODEL INCLUDING
WAKE DISTORTION TERMS
Krothapalli, Krishnamohan R., Georgia Inst. of Tech., USA; Prasad,
J. V. R., Georgia Inst. of Tech., USA; Peters, David A., Washington
Univ., USA; System Identification for Integrated Aircraft Development
and Flight Testing; March 1999, pp. 26-1 - 26-10; In English; See
also 19990032449; Sponsored in part by Georgia Tech./Washington
Univ. Center of Excellence in Rotorcraft Technology; Copyright
Waived; Avail: CASI; A02, Hardcopy; A04, Microfiche
For many years, analysts have been puzzled by the fact that the
off-axis coupling of a helicopter exhibits the opposite sign in flight
tests as compared to simulations. Recently, researchers have shown
that the effect may be attributable to the bending of the wake during
a pitching maneuver, which introduces a fore-to-aft gradient in
induced flow that can reverse the predicted sign of the roll coupling.
Other research has shown that this result can also be obtained with
momentum and vortex theory. There are many issues still under
debate regarding the magnitude of wake distortion and its effectiveness
in predicting off-axis dynamics. In the present work, a generalized
dynamic wake model is augmented to include wake distortions.
This model is then coupled with a flap model for simulation in
low speed forward flight. Frequency responses from the simulation
are collected with and without wake distortion, and these are
compared with wind tunnel test data.
Author
Mathematical Models; Helicopters; Dynamic Models; Data
Processing; Simulation; Flapping; Flight Control
19990032475 Scientific and Technical Research Council of Turkey,
Defense Industries Research and Development Inst., Ankara, Turkey
AERODYNAMIC DATA IDENTIFICATION USING LINEAR AER-
OBALLISTIC THEORY
Mahmutyazicioglu, Gokmen, Scientific and Technical Research
Council of Turkey, Turkey; Platin, Bulent E., Middle East Technical
Univ., Turkey; System Identification for Integrated Aircraft Development
and Flight Testing; March 1999, pp. 30-1 - 30-12; In English;