Although most of these raids were unproductive , there were some successes ; on 1 August , five out of 12 Blenheims sent to attack Haamstede and Evere ( Brussels ) were able to bomb , destroying or heavily damaging three Bf 109s of II. / JG 27 and apparently killing a " Staffelkapitän " identified as a " Hauptmann " Albrecht von Ankum - Frank .