http://www.af.mil/shared/media/photodb/photos/060620-F-9988K-001.JPG
http://www.af.mil/shared/media/photodb/photos/060620-F-9988L-003.JPG
http://www.af.mil/shared/media/photodb/photos/060620-F-9988N-002.JPG
And a story:
When eventually I actually heard one, I was impressed by that deep-pitched siren sound the engines made -- back then, I'd never heard anything like it.