Aerodynamics in focus: BORGWARD's experiments with wind tunnels and woollen threads

Cross reference: Picture is available at AP Images (http://www.apimages.com) and http://ots.de/omzHM

Aerodynamics is certainly one of the most complex issues the automotive industry has to deal with today. Still, in the 21st century, experts can use high-performance computers the size of refrigerators that spend days unravelling the mysteries of air flows. Carl F. W. BORGWARD, who became interested in airplanes, and later helicopters, at a very early age, realised back in the 1930s that aerodynamic principles could be applied to automobiles much in the same way they were used in aircraft construction. On the one hand, this would reduce fuel consumption. On the other, it would enable increases in top speed and acceleration to levels previously undreamed of.

One of BORGWARD's first aerodynamic milestones was the "Windspiel", a four-door saloon that was developed in 1936 and presented at the Berlin Motor Show in March 1937. The car made practical use of the knowledge gained by the leading aerodynamics researcher of the time, Paul Jaray. In terms of its styling, the vehicle also anticipated the Airflyte models that the innovative American automaker Nash began building in 1949. The concept for the vehicle was implemented by BORGWARD's Chief Designer, Herbert Scarisbrick, and Plant Manager Friedrich Kynast. The two even held a patent for the side windows used for ventilation. Although the saloon's engine only had an output of 40 hp, the car was able to reach a top speed of 130 km/h, which said more about its streamlined design than any drag coefficient ever could.

The pontoon-shaped BORGWARD Hansa 1500 had only just been presented in 1949 when work began on a new body variant in a project known as the "Hansa 1800 Fastback." At this point, BORGWARD had already started having vehicles tested in wind tunnels at the Hanover College of Technology and the Research Institute of Automotive Engineering and Vehicle Engines (FKFS) in Stuttgart. The new fastback was an attempt to aerodynamically optimize the pontoon shape. It is no longer possible to say with certainty whether BORGWARD's own wind tunnel for 1:5-scale models was used for the development of the streamlined four-door vehicle. Still, the early investment in such a facility on the southern side of the BORGWARD plant underscores the importance aerodynamics held for the vehicle developers at the Bremen-based company. In any case, the Hansa fastback attracted a great deal of attention at the IAA International Motor Show in Frankfurt in April 1951.

The concept still wasn't completely ready for series production, however. Engine developer Karl-Ludwig Brandt built a six-cylinder engine especially for the fastback

project. The unit delivered an impressive maximum output of 82 hp. The bodywork, on the other hand, was only touched up slightly, and it shed some of its chrome trim during the testing phase. The first models of this aerodynamic wonder - now known as the "Hansa 2400 Sport" - rolled off the line in October 1952. Unfortunately, sales of the unusually shaped vehicle never took off, which is why BORGWARD later launched the 2400 as a notchback saloon as well.

The fact that aerodynamic efficiency and a notchback design go together well was impressively demonstrated by the BORGWARD Isabella, which went into production in 1954 and boasted a surprisingly low drag coefficient (Cd value) of 0.40. By comparison, the Ford 17 M from that time had a Cd value of 0.54. Even more aerodynamic than the Isabella was its successor model - the P 100. The vehicle's panoramic windows and a new trapezoid body shape chosen by BORGWARD designer "Don" Roberto Hernandez also led to new and unforeseen challenges for the wind tunnel experts from Bremen. Initial top-speed tests led the engineers to suspect that the four-door model was not very aerodynamically efficient. Carl F. W. Borgward immediately sent a 1:10-scale wood model to the FKFS wind tunnel in Stuttgart. BORGWARD painted the 1:1 prototype in grey and glued woollen threads onto the body at specific intervals. If the threads lay against the body at high speeds, it was considered to be a sign of good aerodynamics. If they flapped around wildly, the opposite conclusion was drawn. The initial finding was that the aerodynamic problems might have been caused by the prototype's projecting roof line.

The P 100's roof was modified and the vehicle was able to achieve the ambitious top speed of 160 km/h that the engineers had set in the specifications - yet another example of BORGWARD's sophisticated aerodynamic expertise, way back in the early 1960s.


Further information
BORGWARD Group AG Kriegsbergstrasse 11 70174 Stuttgart, GermanyJ├╝rgen Schramek Head of Product Communications Telephone +49 711 7941851043E-mail media@borgward.com www.borgward.com