G. Harry Stine wrote an article called "The First Model Rockets" that appeared in the May 1970 Model Rocketry magazine. He stated that the motors were 0.5" by 2.25" inches, which I think was the size that the later Centuri 13mm motors emulated. The "4" in the designation of the Carlisle motors was 4 Nt-sec. Stine stated that the 4-4-2 motor was the equivalent of a NAR Type B4-4.

His later article in the July 1971 MR magazine was titled "Engines Full Circle". The article includes a picture of the early Carlisle motor through the MPC 13mm Mini-jet motor. The move to 18mm apparently occured in the late 1957 to mid-1958 when the Brown motors were being made. He also states the he met Vern Estes in July '58.
At that time Stine was working with or for MPC and he was plugging rhe motors. I actually was working with Dr. Gregorek and helped static test the Mini-jets for certification along with George Pantalos and Doug Ball at Ohio State.

NARTS does make available a CD of scans of Model Rocketry magazine. My old computer would not open them. But I have the magazines in my lap...

Chas

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Charles Russell, MSgt,USAF (ret.)
NAR 9790, Lvl 1
SAM "Balls Three"