Originally Posted by
IFMU
At 2/3 power and 211 kts S&l, I'd project 258 kts max s&l.
Interesting extrapolation using only one data point.
Lets establish a curve based upon Sikorsky's own statements:
https://www.janes.com/defence-news/n...5-kt-in-flight
The Sikorsky-Boeing SB>1 Defiant coaxial helicopter on 9 June reached a new top speed of 205 kt in flight while using less than 50% of the installed propeller power.
https://www.defensenews.com/digital-...hits-230-knots
211 knots in straight and level flight...the aircraft was using about two-thirds prop torque and engine power to achieve the speeds.
So that's 205 kt @ "less than" 50% power, followed by 211 kt @ 66% power, which would yield a best case blistering 224 kt at MCP (empty)