To: All
When asked why her legs were so long the girl replied they are this long in order to keep my ass off the ground. That is the first reason for the long mast on a teetering rotorhead. It keeps the blades from hitting the tail cone when flying aft or when making a cyclic flare. Everything else is secondary. When Sikorsky first designed the S 55 the tail cone was straight. After a rotorblade incursion on a Chicago Airways S 55 they came up with a mod drooping the tail cone. This was incorporated when they upgraded from the R 1340 to the R 1300 engine.
On several other helicopters with articulated rotorheads they had to incorporate a mast extension in order to raise the blades from the fuselage. This was done to eliminate the compressive drumming sound as the blades passed over the canopy.
------------------
The Cat