Here's the citation as promised:
Wynne, H. Hugh: "The
Motion Picture Stunt Pilots and Hollywood's Classic Aviation Movies." 1987, Missoula, MT: Pictorial Histories Publishing Co.
(The address of the above is/was 713 South Third West, Missoula MT 59801)
There are several pictures of Morses, including a nice three-quarter shot of a Tommy that was crashed for "The Dawn Patrol."
I wondered about the MB-3/S-4 thing. Wynne never refers to either the S-3 or S-4, yet all of his references to Tommys talk about rotary engines. Am I to assume that the MB-3 was a radial-engined variant? Wynne was one of the founders of the US Cross & Cockade Society, so presumably he knew the difference.