and unyielding attitude of the Air Force. They wouldn't give UFOs the chance of existing, even if they were flying up and down the street in broad daylight. Everything had to have an explanation. I began to resent that, even though I basically felt the same way, because I still thought they weren't going about it in the right way. You can't assume that everything is black no matter what. Secondly, the caliber of the witnesses began to trouble me. Quite a few instances were reported by military pilots, for example, and I knew them to be fairly well-trained, so this is when I first began to think that, well, maybe there was something to all this." Hynek remained with Project Sign after it became Project Grudge (though he was far less involved in Grudge than he had been in Sign). Project Grudge was replaced with Project Blue Book in early 1952, and Hynek remained as scientific consultant. Air Force Captain Edward J. Ruppelt, Blue Book's first director, held Hynek in high regard: "Dr. Hynek was one of the most impressive scientists I met while working on the UFO project, and I met a good many. He didn't do two things that some of them did: give you the answer before he knew the question; or immediately begin to expound on his accomplishments in the field of science." Though Hynek thought Ruppelt was a capable director who steered Project Blue Book in the right direction, Ruppelt headed Blue Book for only a few years. Hynek has also stated his opinion that after Ruppelt's departure, Project Blue Book was little more than a public relations exercise, further noting that little or no research was undertaken using the scientific method. Turnaround Hynek began occasionally disagreeing publicly with the conclusions of Blue Book. By the early 1960s—after about a decade and a half of study—Clark writes that "Hynek's apparent turnaround on the UFO question was an open secret." Only after Blue Book was formally dissolved did Hynek speak more openly about his "turnaround". Hynek speculated that his personality was a factor in the Air Force keeping him on as a consultant for over two decades. Some other ufologists thought that Hynek was being disingenuous or even duplicitous in his turnaround. Physicist James E. McDonald, for example, wrote to Hynek in 1970, castigating him for what McDonald saw as his lapses, and suggesting that,