 Thirteen days later , the aircraft left Wendover for Guam , where it received a bomb @-@ bay modification , and flew to North Field , Tinian , on 6 July . It was initially given the Victor ( squadron @-@ assigned identification ) number 12 , but on 1 August , was given the circle R tail markings of the 6th Bombardment Group as a security measure and had its Victor number changed to 82 to avoid misidentification with actual 6th Bombardment Group aircraft . During July , the bomber made eight practice or training flights , and flew two missions , on 24 and 26 July , to drop pumpkin bombs on industrial targets at Kobe and Nagoya . Enola Gay was used on 31 July on a rehearsal flight for the actual mission . 
