Do a search with Yahoo on the topic "flying hammer". You will come up wit a lot of interesting results, but one is the 504th Bomb Group WW2. The web site is www.geocities.com/pentagon/quarters.They did use a flying hammer as the group emblem. They were B-29 group in Pacific. It says, "The Flying Hammer was designed by Gen Martin. He was the Squardron commander for the 421th at the time. He later become the Group commander." It looks like this is personal page of someone who flew in this unit.