Perhaps you are familiar with the monsters from Junker or the Kalinine K-7 from the 30s.
In France, the equivalent would be the surprising SAB AB-20.
It was a large four-engine twin-boom bomber built in 1932. It had a thick-profile flying wing.
Only two prototypes were ever built
Long before the V-22 Osprey, this underpowered 1950s machine already proved the tiltrotor could work.
The Bell XV-3 was an experimental convertiplane built by Bell Helicopter for a joint U.S. Army and Air Force program. It first hovered on August 11, 1955, powered by a single 450-horsepower Pratt & Whitney R-985 radial engine driving wingtip rotors that tilted a full 90 degrees. On December 18, 1958 it became the first aircraft of its kind to complete a full conversion from helicopter mode to airplane mode, eventually logging 110 such transitions and roughly 125 flight hours across more than 250 sorties while reaching 184 miles per hour.
Those hard-won flights directly shaped the designs that followed. 🫡