Sunday, December 31, 2017

Bad Vibrations


  1. KA-25

    "So, Chief, you think you can have it ready for Event One on tomorrow's flight schedule?"

  2. Belay my last; twin, not triple tail, so it's a KA-31

    "Chief, we still need it for the first go in the morning."

  3. GROUND RESONANCE STRIKES again. most effective way out of a ground resonance event is to lift off the pad. shutting down the engine wouldn't save it. this aircraft was tied down. as rotor rpm dropped, so did oscillation frequency. the energy of the resonance oscillation was transferred from frequency to amplitude. rotors strike each other. !QED!
    all it takes is one landing gear shock strut to have a bit less dampening than the others. it's another one of those mysteries of vertical aviation that perplexes and annoys engineers. sorta like Ring State Vortex and why pilots who know better continue to have issues.