The Allison T40 is considered to be a pioneer of turboprop engines. Comprised of two T38's , the engine was highly unreliable and dangerous. Many lessons were learned from early designs and eventually this lead to a redundant T56.

Sources & Credits:

Excellent Breakdown of TurboProps
   • Turboprop Core  Turbine Engines : A ...  

https://www.nationalmuseum.af.mil/Vis...

T56 Engine Run
   • T56 Engine Run  
   • Partida motor T56A15  

   • C2A Greyhound   (C2)

https://www.northropgrumman.com/what...

Music:
"Abstract Background" From Envato
"No Time To Die" From CO.AG MUSIC
   / @co.agmusic