I was finally able to track down one version of the “Big Bad Wulf” story: Martin Caidin’s
Black Thursday, copyright 1960, Ballantine Books paperback edition, (cover painting shows a wounded crewmember being carried away from a B-17 on a stretcher; weird pumpkin-color sky background), no source cited; pp 76 - 77:
“During the height of the period of disastrous missions over the Reich, an American aircraft firm, following the policy that Americans are better than anybody else, sponsored probably the most ill-received advertisement of the war. The advertisement was full page, and it showed a grinning gunner peering through the sights of a .50-caliber machine gun as he poured tracers into a swarm of Focke-Wulf FW-190 fighters. Beneath the heroic painting was the caption: 'Who’s Afraid of the Big Bad Wulf?'
One pilot who saw the page immediately tore it from the magazine and pinned it to his group’s bulletin board. Beneath the page went a long scroll of paper with a red-ink headline that shouted: “WE ARE!”
Every combat officer in the group signed the scroll, and the group commander’s name was at the top of the list. They mailed it to the manufacturer with their blessings.”