Hi,here is a McDonnell Model 81 & 81A tandem rotor assault transport helicopter Project
proposals,maybe submitted to this contest ?.
https://www.secretprojects.co.uk/threads/us-navy-usmc-assault-helicopter-competitions-1950-51.9885/#post-282316
http://aviationarchives.blogspot.com/2017/08/mcdonnell-model-8181a-helicopter.html
-- Edited by hesham on Tuesday 21st of April 2020 07:00:18 AM