University Distinguished Professor &
Alfred Gessow Professor in Aerospace Engineering &
Director Alfred Gessow Rotorcraft Center
University of Maryland, College Park, MD 20742
Phone: 301.405.1122 | Fax: 301.314.9001
Email: chopra@umd.edu

Professional Interest:

Multidisciplinary research in rotorcraft aeromechanics with focus on structural dynamics, aeroelasticity, smart structures and micro air vehicles.

Education:

• Massachusetts Institute of Technology (1974-77)
  Sc. D. in Aeronautics & Astronautics
  Thesis: “Nonlinear Dynamic Response of Wind Turbine Rotors“
• Indian Institute of Science, Bangalore, India (1966-68)
  M.E. with Distinction in Aeronautical Engineering
  Thesis: “A Study of Some Problems in Panel Flutter“
• Punjab Engineering College, Chandigarh, India (1961-65)
  B. Sc. Aeronautical Engineering

Experience:

• National Aerospace Laboratory, Bangalore, India (1966-74)
  Scientist in Structural Sciences Division

  Carried out design, fabrication and testing of dynamically scaled aeroelastic models of typical aircraft wings and satellite launch vehicles in low speed and supersonic wind tunnels.  In parallel, developed vibration and flutter analysis of thin panels that included skewed, trapezoidal and tapered thickness plates.

• Massachusetts Institute of Technology (Sept. 1974 – May 1977)
  Research Assistant, and later Post-Doctoral Fellow in Aero & Astro

  Dynamic Analyses of Wind Turbines: Developed a coupled nonlinear flap-lag-torsion aeroelastic analysis of a horizontal axis wind turbine taking into consideration effects of gravitational loading and earth’s boundary layer, especially for large diameter rotors. Dynamic blade response and parametric resonance instability were investigated systematically for different operating conditions. Limit cycle flutter analysis was carried out using harmonic balance method. Results showed the possibility of sustained limit cycle blade motions at some rotational speeds if large enough disturbance is given to blades (possible with atmospheric gust) (very first study on this topic).

  Stall Flutter and Divergence of Wings: Simple wing models were tested in a low speed wind tunnel for nonlinear stall flutter characteristics. Harmonic coefficients were extracted from the free transient vibration data in pre- and post-stall regions. These coefficients are important to develop dynamic stall models.

• NASA Ames Research Center (June 1977 to May 1978)
  National Research Council Post-Doctoral Fellow

  Dynamic Analysis of Circulation-Controlled Rotors: Theoretical analyses for flight stability and flutter stability of circulation control rotors in hover were formulated (very first time). The effect of trailing edge blowing on the handling qualities of a helicopter in longitudinal and lateral modes and blade flap-lag flutter stability was examined for different flight conditions and rotor configurations. It was shown that the blowing has a powerful effect on blade stability, which should be considered in rotor design. These key findings were useful in subsequent development of the X-Wing aircraft.

• Stanford University (June 1978 to October 1981)
  Senior Research Associate at NASA/Stanford University Joint Institute of Aeronautics and Acoustics

  Dynamic Testing of Full-Scale Rotors in 40 x 80 foot Wind Tunnel: Advanced algorithms were developed on a Dynamic Analysis System (a minicomputer based time series system) for on-line stability measurement of rotors in a wind tunnel. These include: diagnostic blade response and loads, moving-block damping identification, Bode plots and regressing rotor loads analyses. These algorithms were used in various full-scale helicopter rotor tests in the 40 x 80 ft wind tunnel, that include Kaman Circulation Controlled Rotor, Lockheed X-Wing Rotor, Boeing Bearingless Main Rotor, Sikorsky ABC Rotor, and Hughes Advanced Composite Rotor tests. Many of these algorithms are routinely used even today for rotor testing in the 40 x 80 / 80 x 120 ft. wind tunnel (World’s largest wind tunnel).

  Aeroelastic Analysis of Advanced Rotors: Flap-lag-torsion flutter of two new rotor configurations, constant-lift rotor and free-tip rotor was investigated. The effect of several design parameters on flutter boundary was evaluated.

  Finite Element Analysis of Rotor Blades: Finite element aeroelastic analysis of an elastic blade undergoing moderately large coupled flap, lag, torsion and axial deformations was formulated using Hamilton’s approach. Hover stability was calculated from the normal mode equations. The analysis was initially applied to conventional rotors (articulated and hingeless) and later on was extended to include multiple load-path blades such as BMR blades. This was the very first finite element formulation of a bearingless rotor and formed the basis of modern structural analysis of blades.

  Multicyclic Vibration Control: A study was conducted to examine the performance of various active feedback control systems for vibration reduction of helicopters. The controllers studied were: open-loop with off-line identification, closed-loop with off-line identification, open-loop adaptive, and closed-loop adaptive. The on-line identification of model characteristics was performed using a Kalman filter solution. The design implication of different regulators was examined for various flight conditions. This study helped in the selection of a feedback controller for full-scale testing of a rotor system in the 40×80 ft wind tunnel.

• University of Maryland (October 1981 – Present)
  Department of Aerospace Engineering

  October 1981 to June 1986 – Associate Professor
  July 1986 to Present – Professor
  June 1988 to August 1990 – Acting Department Chairman
  From October 1991 – Director Alfred Gessow Rotorcraft Center
  January 1996 to January 2000 – Minta-Martin Research Professor
  From November 1998 – Alfred Gessow Professor
  From January 2009 to August 2009 – Interim Department Chairman

Teaching:

Taught the following undergraduate and graduate courses

• Flight Structures I & II (Undergraduate)
• Vibration & Aeroelasticity (Undergraduate)
• Structural Dynamics (Graduate)
• Aeroelasticity (Graduate, developed new course)
• Helicopter Dynamics (Graduate, developed new course)
• Helicopter Theory (Graduate/Undergraduate)
• Smart Structures (Graduate, developed new course)
• Helicopter Design (Graduate)

Committee member for several Ph.D. and M.S. dissertations in Aerospace, Mechanical, Electrical and Civil Engineering Departments.

Professional Societies Membership:

• AMERICAN HELICOPTER SOCIETY, Honorary Fellow
• AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS, Fellow
• AMERICAN HELICOPTER SOCIETY, Fellow
• AERONAUTICAL SOCIETY OF INDIA, Fellow
• AMERICAN SOCIETY FOR MECHANICAL ENGINEER, Fellow

Service: Professional

• JOURNAL OF THE AMERICAN HELICOPTER SOCIETY
  Associate Editor, 1987-91.
• JOURNAL OF AIRCRAFT
  Associate Editor, 1987-cont.
  Guest Editor, December 1990 and January 1991 Issues.
  Member Editorial Advisory Board, 2002-cont.
• VERTICA, THE INTERNATIONAL JOURNAL OF ROTORCRAFT AND POWERED LIFT AIRCRAFT
  Member Editorial Advisory Board, 1987-91.
• SMART MATERIALS AND STRUCTURES JOURNAL
  Member Editorial Board, 1994-2000.
  Guest Editor, February 1995 Issue.
• JOURNAL OF INTELLIGENT MATERIAL SYSTEMS AND STRUCTURES
  Associate Editor, 1997-cont.
• SADHANA, AN INTERNATIONAL JOURNAL IN ENGINEERING SCIENCES
  Member Editorial Board, 1991-95.
• INTERNATIONAL JOURNAL OF AEROSPACE ENGINEERING
  Member Advisory Board, 2007-11.
• AMERICAN HELICOPTER SOCIETY
  Dynamics Committee Member, 1982-1986, 1991-95, 1999-2002, 2008-12.
  Deputy Chair Dynamics Committee, 1984-1986, 1991-93.
  Chairman Dynamics Committee, 1993-95.
  Member AHS Award Committee, 1991-94, 2011-cont.
  Member Technical Council, 1994-97
  Member Education Committee, 1995-cont.
  Chairman Education Committee, 1995-97
  Member Vertical Flight Scholarship Committee, 1996-00.
  Technical Advisor Federal City Chapter, 1992-cont.
  Faculty Advisor, UM Student Chapter, 1983-93, 2000-cont.
  Test and Evaluation Technical Committee Member, 2003-11.
  UAV Committee Member, 2006-cont.
• AMERICAN SOCIETY OF MECHANICAL ENGINEERS
  Member Technical Committee on Adaptive Structures & Materials, 1993-cont.
  Deputy Chairman Adaptive Structures & Materials Committee, 1996-98
  Chairman, Adaptive Structures & Materials Committee, 1998-00
  Member Aerospace Division Executive Committee, 2000-04
  Chairman of Aerospace Executive Committee, 2002-03
  Member Spirit of St. Louis Medal Selection Committee, 2000-05.
  Member Guggenheim Medal Award Selection Committee, 2003-cont.
  Guggenheim Medal Award Selection Committee, Vice-Chair (04), Chair (05)
  Member Congressional Aviation Committee, 2002-cont.
  Member Adaptive Structures Prize Selection Committee, 2002-10.
• AMERICAN INSTITUTE OF AERONAUTICS AND ASTRONAUTICS (AIAA)
  Member of Committee on Structural Dynamics, 1994-97, 2004-cont.
  Member of Technical Committee on Adaptive Structures, 1997-cont.
• AIAA/ASME/ASCE/ACS/AHS STRUCTURES, STRUCT-URAL DYNAMICS AND MATERIALS CONFERENCE AND ADAPTIVE STRUCTURES FORUM
  32nd Conf., Baltimore, MD, April 1991, Organizer Work-in-Progress Sessions
  34th Conf. San Diego, CA, April 1993, Member Organizing Committee, Rotorcraft Session Chairman
  35th Conf., Hilton Head, SC, April 1994, Member Organizing Committee, Session Chairman
  36th Conf., New Orleans, April 1995, Member Organizer Committee, Organizer Work-in-Progress Sessions
  37th Conf., Salt Lake City, UT, April 1996, Technical Chairman Adaptive Structures Forum
  38th Conf., Kissimmee, FL, April 1997, General Chairman Adaptive Structures Forum
  39th Conf., Long Beach, CA, April 1998, Chair for 3 Sessions
  40th Conf., St. Louis, MO, April 1999, Chair for 3 Sessions
  41st Conf., Atlanta, GA, April 2000, Session Chair
  42nd Conf. Seattle, WA, April 2002, Chair for 3 Sessions
  43rd Conf. Denver, CO, April 2003, Session Chair
• SPIE’s INTERNATIONAL SYMPOSIUM ON SMART STRUCTURES AND MATERIALS
  1993 Conf., Albuquerque, NM, Feb. 1993, Session Organizer
  1st Symposium, Orlando, FL, Feb. 1994, Session Organizer
  2nd Symposium, San Diego, CA, Feb. 1995, Technical Chairman Smart Structures & Integrated Systems Conf.
  3rd Symposium, San Diego, CA, Feb. 1996, Technical Chairman Smart Structures & Integrated Systems Conf., Symposium Executive Co-Chair
  4th Symposium, San Diego, CA, Feb. 1997, Symposium Executive Co-Chair
  5th Symposium, San Diego, CA, Feb. 1998, Symposium Executive Chair
  6th Symposium, Newport Beach, CA, March 1999, Symposium Executive Chair
  7th Symposium, Newport Beach, CA, March 2000, Session Chair and Member Technical Organizing Committee
  8th Symposium, Newport Beach, CA, March 2001, Session Chair and Member Technical Organizing Committee
  12th Symposium, San Diego, March 2004, Member Strategic Committee
• WORKSHOP ON DYNAMICS AND AEROELASTIC STABILITY MODELING OF ROTOR SYSTEMS (ARO)
  1st Workshop, Georgia Tech, Dec. 85, Session Chairman and Member Organizing Committee and Panel Member for Future Research Session
  4th Workshop, University of Maryland, Nov. 1991, Technical Chairman
• SECOND INTERNATIONAL CONFERENCE ON ROTORCRAFT BASIC RESEARCH
  University of Maryland, College Park, MD, Feb. 1987, Technical Chairman
• AMERICAN HELICOPTER SOCIETY
  41st Annual Forum, Fort Worth, TX, May 1985, Dynamics Session Organizer & Chairman
  2nd Decennial Specialists’ Meeting on Rotorcraft Dynamics, NASA Ames, Moffett Field, CA, Nov. 1984, Session Chairman & Organizer
  AHS Technical Specialists Meeting on Advanced Rotorcraft Technology and Life Saving Activities, Utsunomiya, Japan, Nov 2002, Organizing Committee Member
  61st Annual Forum, Grapevine, TX, June 2005, Test & Evaluation Sessions Organizer & Chairman
• EUROPEAN ROTORCRAFT FORUM
  17th Forum, Berlin, Germany, Sept. 1991, Dynamics Session Chairman
  23rd Forum, Dresden, Germany, October 1997, Dynamics Session Chairman
  25th Forum, Rome, Italy, Oct. 1999, Dynamics Session Chairman
  26th Forum, Hague, Netherlands, Sept. 2000, Dynamics Session Chairman
• INTERNATIONAL CONFERENCE ON ADAPTIVE STRUCTURES
  9th Conf., Boston, MA, November 1998, Member Organizing Committee
  10th Conf., Paris, France, November 1999, Member Organizing Committee
  11th Conf., Nagoya, Japan, November 2000, Member Organizing Committee
  12th Conf., College Park, MD, November 2001, General Chair
  13th Conf., Potsdam, Germany, November 2002, Member Organizing Committee
  14th Conf., Seoul, Korea, October 2003, Member Organizing Committee
  15th Conf., Bar Harbor, NH, October 2004, Member Organizing Committee
  Member Organizing Committee: 1998-cont.
• ITR METHODOLOGY ASSESSMENT WORKSHOP (ARMY)
  NASA Ames, July 1988, Panel Member (Future Research Rotor Dynamics)
• INTERNATIONAL SYMPOSIUM ON AEROSPACE SCIENCES AND ENGINEERING
  Bangalore, India, December 1992, Organizing Committee Member
• WORKSHOP ON SMART STRUCTURES (ARO)
  1st Workshop, Arlington, TX, Sept. 1993, Organizing Committee Member
  2nd Workshop, University of Maryland, Sept. 1995, General Chairman
  3rd Workshop, VPI & State University, Sept. 1997, Organizing Comm. Member
  4th Workshop, Penn State, August 1999, Organizing Committee Member
• US-EUROPEAN COMPETITION & WORKSHOP ON MICRO AIR VEHICLES (MAVs)
  1st Workshop, Elmau Castle, Germany, Sept. 2005, Organizing Comm. Member
• SPIE FAR EAST & PACIFIC RIM SYMPOSIUM ON SMART MATERIALS, STRUCURES & MEMS
  Bangalore, India, December 1996, Organizing Committee Member
• ARMY SCIENCE BOARD
  Member, 1997-2002
  Study Group: Army After Next: Feasibility Study of Autonomous Cargo Rotorcraft (1997-98)
  Member Small Arms Industrial Base Study (Senate Investigation), (1999)
  Member US Army Achievement Awards (1999)
  Member ASB Summer Study: Mobility Operations (1999-2000)
  Member Joint Transport Rotorcraft Review Committee (2000)
  Member ASB Summer Study: Power Issues (2000-2001)
  Member Navy Aging Aircraft Review Committee (2001)
  Member Future Aviation for Army Study, (2002)
• BOARD of ARMY SCIENCE and TECHNOLOGY
  Technology Challenges for Micro Air Vehicles, Organizing Member, Dec 2004.
• DoD AIR PLATFORM TARA REVIEW
  Member Review Committee (2006)
  Association of the United States Army’s Institute of Land Warfare: Future of Army Aviation: Invited Panelist on “Technology Development: Now, Pending, Future,” Jan 9, 2013.
  National Academy of Engineering (NAE)
  Member AERONAUTICS & SPACE ENGINEERING BOARD (ASEB) 2007-12.
  Member Aeronautics Research and Technology Roundtable Board, 2011-cont.
  Member: Recapturing NASA’s Aeronautics Flight Research Capabilities, 2011-12
• NASA DECADEL SURVEY OF CIVIL AERONAUTICS 2005-06; Member Steering Committee, Member Structures & Materials Committee
  Member: Fostering Vision for the Future: A Review of NASA Institute for Advanced Concepts Committee; 2009-10.
• NASA AMES RESEARCH CENTER
  Member Army/NASA Rotorcraft Peer Review Committee, August 1999, August 2000
  Member Rotorcraft R&T Road Map Committee, 2004
• DAIMLER CHRYSLER
  Member Peer Review Committee for Actuators & Sensors (S&T), Stuttgart, Germany, December 1999
• DAVID W. TAYLOR NAVAL SHIP RESEARCH & DEVELOPMENT CENTER
  Consultant to X-Wing Project (1983-1990)
  Consultant Tail Rotor Performance of Navy Helicopters (1991-94)
  Consultant Rotor Head Fault Detection (1994-96)
• McDONNELL DOUGLAS HELICOPTER COMPANY
  Consultant for Design Development of a Smart Rotor (1994-01)
• BOEING HELICOPTER COMPANY
  Consultant for Active Rotor Test and Evaluation (2007-08)
• KAMAN AEROSPACE CORPORATION
  Consultant for Tab-Actuated Flap Rotor Development (2004-05)
• PROGENY SYSTEMS CORP
  Consultant for Development of Rotorchute (2003-06)
• TECHNO-SCIENCES
  Consultant for Smart Rotor Development for Swashplateless System (2003-07)
  FlexSys Inc.
  Consultant for Parametric Design Studies for Primary Rotor Controls with Conformal Trailing-Edge Flap (2006)
• AVX CORPORATION
  Preliminary Design of a Personal Helicopter (2004-07)
  ROB & ROB
  Helicopter Accident Investigation, expert witness (2005-06)
• NORTON WHITE (Australia)
  Expert Witness For Rotor Investigation (2007)
• DOD ROTARY WING TECHNOLOGY DEVELOPMENT APPROACH FOR YEAR 2000 & YEAR 2005
  Committee Member, 1994-96.
  Member Rotorcraft R&T Roadmap for Army, 2004
• ARMY RESEARCH OFFICE, NSF, NRC, AFOSR, NASA
  Reviewer Research Proposals, 1983-cont.

Service: University

• CAMPUS
  Senate Member, 1985-88.
  Elected Member Graduate Council, 1989-92, 1996-99, 2001-05
  Member Senate Committee on Education Affairs, 1996-97.
  Member Senate Adjunct Committee on Libraries & Computers, 1987-88.
  Member Recruitment of Provost of Academic Affairs (2001)
  Member Recruitment of Vice President & Dean Grad Studies (2001-02)
  Member NSF Major Research Instrumentation (MRI) Selection, Dec 2004
  Member Graduate Council Faculty Affairs Committee, Nov. 2004-05
  Member Research Council, 2004-2009
• A. JAMES CLARK SCHOOL OF ENGINEERING
  Chairman PCC Committee, 1983-85.
  Member Extension of Engineering Education at UMBC Committee, 1982-83
  Member APT Committee, 1990-92, 1996-00
  Chairman College APT Committee, 1999-00
  Member Staff Award Committee, 1997
  Member Evaluation & Appointment of Dean Destler, 1998
  Member Recruitment of Dean of School of Engineering, 1999-2000
  Member Research Award Guidelines Committee, 2000
  Member Promotion & Tenure Seminar Group 1999-cont.
  Member Dean’s Faculty Advisory Group, 2002-cont.
  Member Minta-Martin Chair Professor Selection, Nov. 2004
  Chair: Clark Construction Chair Professor Renewal, 2012
  Member: Self-Study Department of Mechanical Engineering, 2012
  Alfred Gessow Rotorcraft Center
  Director, 1991-cont.
• DEPARTMENT OF AEROSPACE ENGINEERING
  Acting Chairman, 1988-90
• DEPARTMENT OF AEROSPACE ENGINEERING
  Member of the Graduate Committee, 1982-94, 1996-cont.
  Chairman, Graduate Committee, 1987-92
  Chairman Faculty Search Committee (Rotorcraft & Smart Structures), 1992-93
  Department Reorganization Committee, 1994
  Chairman Aeroacoustics Faculty Search Committee, 1996-97
  Member Executive Committee, 1994-95, 96-cont.
  Member Department Internal Review Committee, 1995
  Member Chairman Selection Committee, 1996
  Member Business Administrative Search Committee, 1995
  Member Merit Review Committee, 1995-97, 1999-cont.
  Chairman Recruitment Committee for Research Engineer, 1996
  Member Academic Coordinator Search Committee, 1997-98
  Member Department Plan of Organization Committee, 1998
  Member Search Committee (Small Smart Devices), 1999
  Member Department Hall of Fame Selection Committee, 1998-cont.
  Chairman Flight Dynamics & Control Faculty Search Committee, 1999
  Member Graduate Requirements Review Committee, 2000-01
  Member Search Committee (Nano-technology and smart devices), 2001
  Chairman Department Internal Review (Self-Study) Committee, 2002
  Chairman Department Chair Review Committee, 2002
  Member of Search Committee for Langley Professor, 2003-04
  Member of Search Committee for Small Smart System Faculty, Sept 04-cont.
  Member Department Chair Search Committee, 2006
  Chairman Faculty Search Committee, 2005-cont.
• NATIONAL NEEDS FELLOWSHIP PROGRAM
  Committee Member, 1988 – 2000, (About 25 fellowships for women and minority students)
• SIGMA GAMA TAU SOCIETY
  Faculty Advisor, 1999-2007

Service: Community Service

• DUVAL HIGH SCHOOL (P. G. COUNTY)
  Member of School Advisory Board, 1989 – 2003
• SIKORSKY MINORITY FELLOWSHIP FOR UNIVERSITY OF MARYLAND
  Instrumental for 3 Minority Fellowships for engineering students starting from 1993.

Short Courses:

• One week course on “Helicopter Aerodynamics and Aeroelasticity” taught at the following organizations (with Professor Alfred Gessow):
  Edwards Air Force Base, California, August 1983
  The University of Kansas, Lawrence, Kansas, August 1983
  NASA Langley Research Center, Hampton, Virginia, Jan. 1984
  Patuxent Naval Air Center, Maryland, January 1984
  Singer-Link, Binghampton, New York, June 1985
• One week course on “Helicopter Dynamics” taught at McDonnell Douglas Helicopter Company, June 1990.
• One Week Short Course on Smart Materials and Structures Technology (with Balachandran, Baz, DeVoe, Pines, Sirkis, Wereley), University of Maryland, June 1-5, 1999
• One Day Short Course on Smart Structures Theory (with Norman Wereley), at 1998, 1999 and 2000 SPIE Smart Structures Symposiums
• Visiting Professor at Australian Defense Academy, Canberra, One week Short Course on Helicopter Theory, July 1998
• Visiting Professor at Nanjing Aeronautics and Astronautics University, China, One Week Short Course on Smart Structures Theory and Applications, December 1998.
• Visiting Professor at Kunkuk University,Korea, One Week Short Course on Helicopter Dynamics Theory, February 2007.
• One week short course & Consulting on “Helicopter Aeromechanics and Advanced Designs” at Korea Aerospace Research Institute (KARI), Daejeon, Korea, June 27-30, 2011.
• One week consulting on “Helicopter Rotor Designs” at Turkish Aerospace Industries (TIA) at Ankara, Turkey, December 12-16, 2011, Dec 12-19, 2012.