Emeritus Professor Egbert Torenbeek passed away
On 29 August 2024, our much-esteemed former colleague Professor Egbert Torenbeek passed away at the age of 85. Egbert Torenbeek (1939) graduated in aeronautical engineering from TH Delft in 1961. He developed into a Professor of Aircraft Design (1980) and wrote the world-famous book ‘Synthesis of Subsonic Airplane Design’ (1976), also known as the ‘the Torenboek’. This book is still used worldwide as a basic book for aircraft design and design education.
In the 1990s, Torenbeek was closely involved in the design of a six-seat propellor aircraft. This aircraft, the Extra-400 which first flew in 1996, was the first ever 100% plastic production aircraft. For the last three years before his retirement in 2000, Egbert Torenbeek was Conrector of TU Delft. In the same year, he received an honorary doctorate from the Moscow Aviation Institute and, in 2013, the prestigious Aircraft Design Award from the AIAA. His book ‘Advanced Aircraft Design’ (Wiley, 2013) was received by the trade press as ‘an indispensable reference work for students, researchers, aircraft designers and analysts.’ He returned his honorary doctorate to Moscow in protest immediately after the MH17 disaster (in 2014). In 2016, he was awarded the prestigious Ludwig Prandtl Ring.
Prof Torenbeek was an aircraft designer pur sang and an inspiration to entire generations of aviation engineers.
Anyone wishing to share a memory of Torenbeek can do so via this link or the book of condolences in the faculty entrance hall.
Read an interview with Professor Torenbeek in the pioneer book or on the website of TU Delta (Dutch only).
In Memoriam Egbert Torenbeek 1939-2024
"Death does not exist. What exists is life, even if it is less than a wisp of mist in the oceans of time" - Jeroen Brouwers
Professor ir. Egbert Torenbeek has passed away at the age of 85, but his influence on the field of aircraft design will continue for many years to come. I got to know Egbert when I started working as Assistant Professor at TU Delft in 2009. We quickly developed a strong bond due to our fascination with aircraft design. I began my studies in Aerospace Engineering in 2000, the year Egbert retired. Therefore, during my studies, I had hardly heard the name “Torenbeek.” That changed when I went to the United States to pursue a PhD degree, and everyone seemed to know his book Synthesis of Subsonic Airplane Design. Given his status, I initially addressed him as “Professor Torenbeek.” However, Egbert wanted us to be less formal, and from then on, I addressed him simply as “Egbert.”
Before his retirement in 2000, Egbert was vice-rector of TU Delft. However, his heart lay in design education. From 1964, he was involved in the so-called Preliminary Design Exercise, a project in which students had to design an aircraft on an individual basis. Methods were needed for this design exercise, and Egbert developed them himself, eventually leading to his book Synthesis. At that time, design was done using a slide rule and drawing paper, on which a three-view drawing of the aircraft had to be made. Later, students could also do this using Computer-Aided Design (CAD), a new research field to which Egbert actively contributed from the late 1970s. Under his leadership, aircraft design software was developed by his PhD students.
It is well known that Egbert was a successful writer. More than 15,000 copies of Synthesis have been sold. You will find his books in the design department of every aircraft manufacturer. Other authors, such as Jan Roskam, often borrowed Torenbeek’s methods, with “Courtesy of Egbert Torenbeek” mentioned in their work. His methods for weight estimation are still widely used at universities and research institutes. At every conference I attend, presentations are referencing a “Torenbeek method.” That always gives me a good feeling.
Besides Synthesis, Egbert published more works. The book Aeronautiek (DUP, 2002), which he wrote together with his mentor Hans Wittenberg, is a beautiful Dutch book about the foundations and techniques of flying. Later, Egbert translated it to English and it was published under the name Flight Physics (Springer, 2009). In 2013, the book Advanced Aircraft Design (Wiley, 2013) was published, which he considered his best book. Afterward, he took on his final project: writing a book about the preliminary design of supersonic commercial aircraft. This book was published in 2020, amid the COVID-19 crisis, under the title Essentials of Supersonic Commercial Aircraft Conceptual Design. As with all his books, it is characterized by a high degree of quality in both language and graphical representation.
One of the experiences Egbert liked to talk about was his time at Lockheed in Marietta, GA. In 1977, he stayed there with his family for a year to gain industry experience. There, he met the recently deceased Leland Nicolai, another prominent name in aircraft design. Lee and Egbert got along very well and had a friendly relationship. When they met again in 2013, it turned out that their friendship still existed, and they exchanged wonderful stories from the time they were both at Lockheed.
That these two met was no coincidence, as Egbert received the prestigious AIAA Aircraft Design Award, an annual award for a team or individual who has made a significant contribution to the field of aircraft design. That year, I traveled to Los Angeles with Egbert. He visibly enjoyed the attention and praise that came with the award. Two years later, this happened again when he received the
Ludwig Prandtl Ring from the German DGLR. He shared this wonderful experience with great pleasure upon his return and was very happy with it.
Besides his interest in aircraft and design, Egbert was interested in music, literature, and philosophy. He could talk extensively about the work of Baruch Spinoza, one of the founders of the Enlightenment. He also greatly enjoyed classical music. He played the church organ himself and took lessons until old age. When a conference was organized in Delft in 2015, he invited many international colleagues to listen to a small organ concert at the Maria van Jessekerk and gave a demonstration of the organ's workings. Many remember this with great pleasure.
Egbert was proud of the honorary doctorate from the prestigious Moscow Aviation Institute, which he had received in 2000. However, after the downing of flight MH17, he no longer wanted anything to do with it. Accompanied by a firm letter, he sent back the honorary doctorate and removed the doctoral title from his nameplate. He was once again Prof. ir. Torenbeek. In 1988, he himself was the honorary promoter of Burt Rutan, the legendary aircraft designer of, among others, the Voyager, the first aircraft to fly nonstop around the world. Egbert brought Rutan to Delft and presented him with the honorary doctorate.
Egbert was most proud of “his” Extra 400. He could talk extensively about his contact with Walter Extra and how the project came about. He did the entire preliminary design of the aircraft according to the methods of his book. The aircraft was entirely built from fiber-reinforced plastic, something that had never been done before. “But,” Egbert confided in me, “I just calculated the weight using my method for metal aircraft, and that worked fine.” Yet he was also critical of his own design because, in hindsight, he would have liked to have seen the door opening of that high-wing aircraft done differently. He closely followed the development of the “400” and was thrilled that the aircraft went into production in 1994.
Until 2020, Egbert could still be found at the faculty twice a week, working on his book. He enjoyed talking to young colleagues about the aircraft industry and other topics. When the faculty celebrated her 75th anniversary, Egbert was interviewed for the anniversary edition “Nine Pioneers.” He spoke about what he had experienced in his long career at TU Delft. He concluded with the words: “It has been a wonderful time.” And so it has.
Dr. Roelof Vos, Associate Professor Flight Performance and Propulsion