Construction of the 4" aluminium/glass fibre/carbon fibre N-motor rocket, one of three flight vehicle designs built by our team for the BALLS 10 experimental launch held at Black Rock Desert in Nevada, in 2000. The rockets were designed by the project's initiator, Swiss Federal Institute of Technology Professor Eugene Trubowitz, who subsequently invited me to be a main partner in logistics, financing, construction, and launch.
The 4" aluminium/glass fibre/carbon fibre rocket consisted of a Dr. Rocket 98 mm aluminium N motor case doubling as a load bearing airframe structure, and an upper airframe section of the same diameter, made from glass fibre. The custom-made nose cone was manufactured from carbon fibre and steel.
The rocket's three Anticorodal-110 T6 aluminium fins were welded directly to the motor case. They measured 317.5 mm by 114.3 mm, at a strength of 4 mm. We initially contracted the welding to the renown Pilatus aircraft factory in central Switzerland. The results were startlingly disappointing, however. While the welds were of a clean external appearance (top photo), Pilatus had actually welded right through the motor case, thus rendering the entire component unusable. We were suitably surprised; this was a reputed aircraft factory, and they had promised us an expert job.
As we were working on three different rockets at the same time and thus were subjected to a tight schedule until the launch date at the end of September 2000, we purchased another motor case and had Dr. Rocket courier it immediately across the Atlantic. This time, we contracted the welding of a new set of fins to E. Nussbaumer AG, an aluminium welding shop in Bremgarten, a small town in the Swiss countryside. The second photo from the top shows Professor Trubowitz (far right) explaining the work to be done to an employee of E. Nussbaumer AG, using the damaged motor case as an example. Nussbaumer's welding was fantastic, and we were finally able to proceed with the remaining construction of the rocket.
The lower two photos show the thus completed tail section of the rocket at the Swiss Federal Institute of Technology's machine shop. Fins and motor case have been masked, leaving only the welds exposed, in anticipation of the application of an aerodynamic fillet consisting of an epoxy mixture. The second photo from the bottom shows the tail section of another one of the project's three rockets in the background, the 4" glass fibre/carbon fibre vehicle.
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