 Complete the following phrase:  On 3 and 4 February 1942, Clausen and Oberleutt Friedrich Geißhardt shot down three Polikarpov R-5s or Polikarpov R-Zs of 622 LBAP Legkii Bombardirovochnyy Aviatsionyy PolkLight Bomber Aviation Regiment and 672 LBAP. Clausen became an ace-in-a-day for the first time on 9 March 1942, claiming aerial victories 36 to 40. Following the 