You would think that turboprop engines on a Lockheed Super Constellation would be a slam dunk, and while the turbo Connie was quite fast, the airlines still weren’t that sure about the new fangled engines, and they decided to sit this one out until the jet airliners came around. Still, the US Navy ordered four R7V-1 Super Connies to be modified with four Pratt & Whitney YT34-P12A turboprop engines, squared propellers and a shortened wing, and that aircraft received the designation R7V-2. Lockheed leased one back from the Navy to use as a test aircraft for the upcoming L-188 Electra. The Air Force ordered their own pair of turbo Connies, designated as the YC-121F. Despite the promise of the turboprop engines, including their decided speed and range advantage over the original radial engines, only six were built. Still, the Air Force learned much about the new engines that was put to use on the Lockheed C-130 Hercules and the Douglas C-133 Cargomaster. And the turpoprop L-188 Electra would be developed into the P-3 Orion, which served for over 50 years.