 Complete the following phrase:  After its first flight in March 1939 and some small modifications made during an uncompleted development programme, the PWS-102 competed in the ISTUS International Glider Contest held in Lwów in May. It was placed fifth. One production model was completed and flew before the outbreak of World War II, with a second under construction. All three airframes were taken by the U.S.S.R in late September during the 