Originally Posted by
SplineDrive
A 4 bladed rotor will interact with 3/4/5P harmonic blade loads. Those harmonic blade loads WILL end up as vibratory hub loads that must be mitigated somehow. Studying a helicopter dynamics textbook will show that. It’s not just a matter of “poor blade tuning” these aircraft struggle with, it’s the intersection of concept and physics.
I used to be a Sikorsky/X2 guy. I'm probably not at liberty to say the particulars but I'll say you have your harmonics wrong with respect to what was creating vibes and what wasn't.
Originally Posted by
SplineDrive
Maybe Sikorsky finally gets a really excellent anti-vibration control system working for all flight conditions. Maybe they lose both FVL contracts. We’ll see.
I have no knowledge of Raider or Defiant, but they got it working for X2. I personally don't see any reason why it wouldn't work for the new aircraft. They have excellent dynamics people, not just in theory but supporting the aircraft in the field and in the air.