About the Author

About the Author

Sonja Englert is a German aeronautical engineer and test pilot. At 16, she started flying gliders, soon adding motorgliders and airplanes to her ratings. While still in high school, she worked as an intern at a German sailplane factory. After her Abitur, she studied aeronautical engineering at the Technical University of Braunschweig, where she gained the equivalent of a Masters Degree.

During her time as a student, she joined the Akaflieg Braunschweig, a group of students who spend their spare time designing, building and flying gliders. Sonja participated in building the high performance SB13 flying wing glider, which made its first flight 1988. For the following project, the SB14, she designed the composite wing structure as part of her thesis.

During that time, as part of the IDAFLIEG, she participated in several flight test camps, which are dedicated to measuring performance and flying characteristics of gliders. The subjects of her Akaflieg test projects were investigations of drag reduction and quantifying the spin characteristics of gliders.
As a highlight, in 1992, she became the German female National Cross Country Soaring Champion (DMST) flying the SB 11, one of the Akafliegs older designs.

She now works as a consultant for companies and individuals with airplane design projects. She has written several books for aircraft homebuilders . Some of the recent projects are:

Electric airplane project EP Systems / eDA40: support of battery development for aviation / certification, electric motor installation in Diamond DA-40 airplane, flight test preparation, test plans, hazard analysis.

Electric airplane project Bye Aerospace: first flight of StratoAir Net (electric motor glider), performed a number of flight tests on the eFlyer proof of concept plane, flight data analysis.

Design and analysis for Spitfire Replica project (experimental).

Flight data analysis for a Red Bull air race team including performance and engine cooling analysis.

Engineering support (loads & structure) and flight test preparation and support for the QS3 Nighthawk project (powered by Diesel engine).

Engineering support and flight test of Flight Design F2 (EASA), performed first flight, full LSA flight test program, data analysis, flight manual, test plans & hazard analysis.

Flight test of Flight Design / Vessel (South Korea) KLA 100 (LSA).

Design, construction & flight testing of Caro 1, a two-place, high performance composite motorglider.

Support of various other customer’s projects in the areas of flight test, engine installation, engine cooling, loads, conceptual & aerodynamic design, composite structures analysis. See the “Projects” page for more details.


Prior to 2009, Sonja worked for a number of companies:

Lancair/Columbia/Cessna (Bend, OR)
Engineering Test Pilot, Powerplant Project Engineer
Development and certification of Columbia 350 & 400, powerplant & fuel system installations & flight testing, DER test pilot, flight analyst and powerplant engineering
Adam Aircraft Industries (Denver, CO)
Powerplant Lead Engineer
Front & aft engine installations on Adam A500 including induction system, engine cooling system, fuel system
Design of prototype composite tail & boom structure with main landing gear attachment
Mod Works Inc. (Punta Gorda, FL)
Chief Design and Flight Test Engineer
Development of airplane modifications, mainly on Mooneys, Cessna 337, GAP Diesel engine.
Design, fabrication, installation, testing and flight evaluation of numerous modifications.
Completed 12 STC projects.
Korff (Germany)
Aerodynamic and Structures Engineer
Design of extended laminar flow (75 to 85%) airfoil series with good stall characteristics.
CAD design of a composite light airplane wing with the newly developed airfoils.
Performance and structural analysis of the wing for FAR 23 loads
MDB Daetwyler (Switzerland & Malaysia)
Design and Test Engineer
Component design, structural analysis and certification of newly developed two-seat all–metal aerobatic airplane.
Conducted some flight tests for certification.
Conducted a full-scale fatigue test of the wing.
Stress analysis and static tests for increase in gross weight and other modifications.


Sonja has accumulated >5000 h with a FAA commercial airplane and glider pilot license, with instrument and multiengine rating, and EASA LAPL-A and German Sport Pilot license. She is a member of the Society of Experimental Test Pilots and she has flown more than 90 aircraft models, of which about 40 were gliders and motorgliders. Flight test work has accounted for more than 650 flights. She enjoys flying a homebuilt Pulsar and her Caro 1 motorglider.