From the article comments: "...San Francisco had a 900 series convertible engine that had a jet turbine as well..." Ah, here it is: https://www.sae.org/public

From the article comments: "...San Francisco had a 900 series convertible engine that had a jet turbine as well..." Ah, here it is: https://www.sae.org/publications/technical-papers/content/650462/ https://www.sae.org/publications/technical-papers/content/65...