Hey Bill. Just when you thought you had seen it all..... This one of yours looks very much like the one in Pete's book, with the exception of the brass hilt.
Yours has the hump which definitely separates it from the model 15, but the long, stainless steel hilt definitely is what differentiated it from the model 15. It was protection of the hands with the gloves on. In the design, the hilt, rounded (dull) top clip, and cutout in the tang, were the intended design differences from the airman. This one is 2 out of 3. So I guess a hybrid Astro / Airman.
Is the top clip sharp or dull?
Did a sheath come with it Bill? How did you date it pre 1963?
Overall a cool knife. Thanks Bill.