About me:

I conduct theoretical and experimental research to better understand the aerodynamics and acoustics of helicopters.  I work at NASA Langley Research Center in Hampton, Virginia, as a part of the Aeroacoustics Branch.

Publications:

Journal Papers

• Greenwood, E., and Sim, B.W., "Effects of Crosswind Flight on Rotor Harmonic Noise Radiation," Journal of Aircraft, Vol. 55, No. 5, September 2018, pp. 2137-2148.
• Greenwood, E., and Schmitz, F.H., "A Parameter Identification Method for Helicopter Noise Source Identification and Physics-Based Semiempirical Modeling," Journal of the American Helicopter Society, Vol. 63, No. 3, July 2018, pp. 1-14.
• Greenwood, E., Schmitz, F.H., and Sickenberger, R.D., "A Semiempirical Noise Modeling Method for Helicopter Maneuvering Flight Operations," Journal of the American Helicopter Society, Vol. 60, No. 2, April 2015, pp. 1-13.
• Stephenson, J.H., Tinney, C.E., Greenwood, E., Watts, M.E., "Time frequency analysis of sound from a maneuvering rotorcraft," Journal of Sound and Vibration, Vol. 333, No. 21, October 2014, pp. 5324–5339.
• Greenwood, E., and Schmitz, F.H.  "Separation of Main and Tail Rotor Noise from Ground-Based Acoustic Measurements,"  Journal of Aircraft, Vol. 51, No. 2, March 2014, pp. 464-472.
• Greenwood, E., and Schmitz, F.H.  "Effects of Ambient Conditions on Helicopter Rotor Source Noise Modeling," Journal of Aircraft, Vol. 51, No. 1, January 2014, pp. 90-103.

Conference Papers

• Greenwood, E., "Dynamic Replanning of Low Noise Rotorcraft Operations," presented at the Vertical Flight Society 75th Annual Forum, Philadelphia, PA. May 2019.
• Christian, A., Caston, J., and Greenwood, E., "Regarding the Perceptual Significance and Characterization of Broadband Components of Helicopter Source Noise," presented at the Vertical Flight Society 75th Annual Forum, Philadelphia, PA. May 2019.
• Greenwood, E., "Estimating Helicopter Noise Abatement Information with Machine Learning," presented at the American Helicopter Society 74th Annual Forum, Phoenix, AZ. May 2018.*
• Greenwood, E., "Real Time Helicopter Noise Modeling for Pilot Community Noise Awareness," presented at NOISE-CON 2017, Grand Rapids, MI. June 2017.
• Greenwood, E., "Helicopter Flight Procedures for Community Noise Reduction," presented at the American Helicopter Society 73rd Annual Forum, Fort Worth, TX. May 2017.
• Greenwood, E., Sim, B.W., and Boyd, D.D., "The Effects of Ambient Conditions on Helicopter Harmonic Noise Radiation: Theory and Experiment," presented at the American Helicopter Society 72nd Annual Forum, West Palm Beach, FL. May 2016.*
• Watts, M.E., Greenwood, E., and Stephenson, J.H., "Measurement and Characterization of Helicopter Noise at Different Altitudes," presented at the American Helicopter Society 72nd Annual Forum, West Palm Beach, FL. May 2016.
• Malpica, C., Greenwood, E., and Sim, B.W., "Parametric Investigation of the Effect of Hub Pitching Moment on Blade Vortex Interaction (BVI) Noise of an Isolated Rotor," presented at the American Helicopter Society 72nd Annual Forum, West Palm Beach, FL. May 2016.
• Malpica, C., Greenwood, E., and Sim, B.W., "Helicopter Non-Unique Trim Strategies for Blade-Vortex Interaction (BVI) Noise Reduction," presented at the American Helicopter Society Technical Meeting on Aeromechanics Design for Vertical Lift, San Francisco, CA. January 2016.
• Greenwood, E., Rau, R., May, B., and Hobbs, C., "A Maneuvering Flight Noise Model for Helicopter Mission Planning," presented at the American Helicopter Society 71st Annual Forum, Virginia Beach, VA. May 2015.*
• Stephenson, J.H., and Greenwood, E., "Effects of Vehicle Weight and True Versus Indicated Airspeed on BVI Noise During Steady Descending Flight," presented at the American Helicopter Society 71st Annual Forum, Virginia Beach, VA. May 2015.
• Greenwood, E., and Sim, B.W., "The Effects of Crosswind Flight on Rotor Harmonic Noise Radiation," presented at the American Helicopter Society 69th Annual Forum, Phoenix, AZ. May 2013.
• Greenwood, E., Schmitz, F.H., and Sickenberger, R.D., "A Semi-Empirical Noise Modeling Method for Helicopter Maneuvering Flight Operations," presented at the American Helicopter Society 68th Annual Forum, Fort Worth, TX. May 2012.*
• Watts, M.E., Snider, R., Greenwood, E., Baden, J., "Maneuver Acoustic Flight Test of the Bell 430 Helicopter," presented at the American Helicopter Society 68th Annual Forum, Fort Worth, TX. May 2012.
• Greenwood, E., and Schmitz, F.H. "The Effects of Ambient Conditions on Helicopter Rotor Source Noise Modeling," presented at the American Helicopter Society 67th Annual Forum, Virginia Beach, VA. May 2011.*
• Greenwood, E., and Schmitz, F.H., "A Parameter Identification Method for Helicopter Noise Source Identification and Physics-Based Semi-Empirical Modeling," presented at the American Helicopter Society 66th Annual Forum, Phoenix, AZ. May 2010.
• Greenwood, E., and Schmitz, F.H., "Separation of Main and Tail Rotor Noise Sources from Ground-Based Acoustic Measurements Using Time-Domain De-Dopplerization," presented at the 35th European Rotorcraft Forum, Hamburg, DE. September 2009.
• Greenwood, E., Schmitz, F.H., Gopalan, G., and Sim, B.W., "Helicopter External Noise Radiation in Turning Flight: Theory and Experiment," presented at the American Helicopter Society 63rd Annual Forum, Virginia Beach, VA.  May 2007.*
• Schmitz, F.H., Greenwood, E., Sickenberger, R.D., Gopalan, G., and Sim, B.W., Conner, D.A., Moralez, E., and Decker, W.A., "Measurement and Characterization of Helicopter Noise in Steady-State and Maneuvering Flight," presented at the American Helicopter Society 63rd Annual Forum, Virginia Beach, VA.  May 2007.

 _{*Selected as "Best Paper in Session"}

Technical Reports

• Watts, M.E., Greenwood, E., Smith, C.D., and Stephenson, J.H., "Noise Abatement Flight Test Data Report," NASA TM-2019-220264, NASA Langley Research Center, Hampton, VA. March 2019.
• Conner, D.A., Stephenson, J.H., Sim, B.W., Watts, M.E., Greenwood, E., and Smith, C.D., "Joint Eglin Acoustics Week 2013 Data Report," NASA TM-2017-219681, NASA Langley Research Center, Hampton, VA. November 2017.
• Boyd, D.D., Greenwood, E., Watts, M.E., and Lopes, L.V., "Examination of a Rotorcraft Noise Prediction method and Comparison to Flight Test Data," NASA TM-2017-219370, NASA Langley Research Center, Hampton, VA. January 2017.
• Watts, M.E., Greenwood, E., Sim, B.W., Stephenson, J.H., and Smith, C.D., "Helicopter Acoustic Flight Test with Altitude Variation and Maneuvers," NASA TM-2016-219354, NASA Langley Research Center, Hampton, VA. December 2016.
• Watts, M.E., Greenwood, E., Smith, C.D., Snider, R., Conner, D.A., "Maneuver Acoustic Flight Test of the Bell 430 Helicopter Data Report," NASA TM-2014-218266, NASA Langley Research Center, Hampton, VA. May 2014.

Thesis and Dissertation

• Greenwood, E., A Physics-Based Approach to Characterizing Helicopter External Noise Radiation from Ground-Based Noise Measurements. M.S. Thesis, Schmitz, F.H. (Advisor). University of Maryland, 2008.
• Greenwood, E., Fundamental Rotorcraft Acoustic Modeling from Experiments (FRAME). Ph.D. Dissertation, Schmitz, F.H. and Hubbard, J.E. (Advisors). University of Maryland, 2011.

Curriculum Vitae

LinkedIn Profile

ResearchGate Profile

A very nice article about my work featured on nasa.gov. 

Another nice article featuring FRAME written by Frank Colucci for Vertiflite.