First flight of the Sikorsky VS-300 (2nd configuration)
Wednesday, March 6, 1940
- Stratford Army Engine Plant, United States of America 
This is a Notable Operational milestone.
Description:
In this configuration cyclic pitch control was locked out and replaced by two horizontal tail rotors.
Source: "S-46/VS-300/VS-300A Helicopter", Jimmy Devine, Sikorsky Product History | Sikorsky Archives web site, January 2013
