Rigid Rotor,
Any reason why the ducted pusher-prop variant XH-59B (which was a natural follow-up to the 59A) was abandoned ?
Here is more information related to your question.
Perhaps the larger question might be; What developmental work has Sikorsky done that was not funded by the government?
Perhaps a related question might be; Would the helicopters have been Intermeshing-ABCs if Charles Kaman had not been told
"Charlie, we have our inventor at United Aircraft. His name is Igor Sikorsky. We don't need another one."
Dave