Complex sentence: The ASK 18 was designed by Rudolf Kaiser and was the last Schleicher glider to use the traditional construction method, at a time when contemporary aircraft of the same class, such as the Grob G-102 Astir, were made of glass-fibre.
Split into simpler sentences: The ASK 18 was designed by Rudolf Kaiser and was the last Schleicher glider to use the traditional construction method. It was built when aircraft of the same class, such as the Grob G-102 Astir, were made of glass-fibre.