Consultants

Groen Brothers Aviation retains a number of consultants in key technological and financial areas including:

Walter Sonneborn
GBA Chief Engineer Heliplane Project (internal consultant).

Formerly Head of Research and Development at Bell Helicopter, retired following a distinguished career of 40 years at Bell. Mr. Sonneborn currently holds the record for having developed the fastest rotor wing aircraft in history. Mr. Sonneborn is the recipient of the 2005 American Helicopter Society (AHS) Alexander A. Nikolsky Honorary Lectureship award. Mr. Sonneborn is the GBA Chief Engineer on the Heliplane project.

Dan M. Somers
Aeronautical Engineer Consultant

Dan Somers has been the President of Airfoils, Inc. since 1980, located in Pennsylvania. Mr. Somers is an internationally recognized expert in airfoil design, analysis, and testing. He designed, along with Richard Eppler, the Eppler Airfoil Design and Analysis Code, a program considered to be unequaled in the world. In addition to designing the airfoil of the Hawk series rotor blades, Mr. Somers has designed airfoils for wind turbines, sail planes, cruise missiles, business jets, and others. Prior to operating his present company, Mr. Somers worked as a research engineer at NASA Langley Research Center. Mr. Somers also has many publications to his credit.

Dr. Mark D. Maughmer, Ph.D.
Aeronautical Engineer Consultant

Dr. Mark Maughmer has been a Professor in the Department of Aerospace Engineering at Pennsylvania State University since 1984. Dr. Maughmer optimized the rotor blade platform for the Hawk gyroplane series and performed the parametric study using the Dr. McCormick's program. Dr. Maughmer has consulted with many large aerospace companies and government agencies. He is a widely published author on the topics of airfoil design and analysis, wing platform optimization, natural laminar flow aerodynamics, and subsonic, low turbulence wind-tunnel design and operation.

Both Dan Somers & Dr. Maughmer are recognized experts on rotorcraft blades and airfoil design. Working together with  Dr. Barnes McCormick, a Boeing Professor Emeritus in the Deptartment of Engineering at Pennsylvania State University, they designed the family of natural laminar-flow airfoils for the rotor of the Hawk 4 gyroplane. The design specifications for the airfoils were determined from rotor-performance calculations performed by Dr. Maughmer, using a computer code developed especially for gyroplane rotors by Dr. McCormick. All of this was done under the supervision of Dan Somers, an internationally recognized airfoil design specialist.