EC135 at FL100 - rudder problem

  • Just tried it and it worked fine, as expected the first limit indicators quickly showed N1 as the limiting factor, 100% N1 at 62% torque.

    Tail rotor was effective throughout take off, transition, and climb away at full power.

    Impressed at how close to the real thing it was. I've flown over 4000 hours in the 135, though not much at that altitude (not too much crime to solve at 10,000').

  • The thing is, with AFCS on a 360° yaw takes about 2.5 seconds in each direction. With AFCS off, a left yaw while hovering out of the ground effect is not possible. A strong right yaw is possible, but nearly impossible to recover.

    Basically turning off the AFCS inflight at that altitude will lead to an uncommanded right yaw.

  • The limitation for yaw rate is 60 degrees per second, so it should take no less than 6 seconds to complete as spot turn. It's wise to check the power requirement (and limitation) in the hover by gradually turning against the torque, that way you know you'll be able to stop the yaw with the opposite pedal without over torqueing/FLI limit. If you do run out of power when operating OGE at altitude, just reduce the collective and get the nose down, gain airspeed and then carefully return to the hover again where possible.

    The 135 can be very nervous to crosswinds with that big fin, great for forward flight (65Kts and above), but a handful in gusting crosswinds at slow speeds.

    Flying for the police means a lot of time in the out of ground effect hover or very slow fuel saving orbits at or near MAUW, certainly keeps the feet and knees busy!

    The big thing is to anticipate to prevent getting into a situation that can bite.

  • Why are you AFCS off? I wouldn't expect to have the power available at FL100 OGE to be turning left, you're right at the edge of the flight envelope if your managing to hover there, never mind spot turning. I would expect to be severely power limited OGE at in that scenario. IGE hover might be possible depending on payload.

  • I tried the same thing at LOWI, much less rudder authority with the AFCS off.


    Hover the 135 with AFCS on at about sealevel. Pick a spot nearby or on the horizon. Kick in full left rudder. Once the spot goes through, take time. Do three spins around your own axis, will be about 6-7 seconds.

    Now do the same thing with AFCS off. I had about 11 seconds.

    Can the devs adress this please? Should I open a bugticket?

    Edited once, last by frumpy (August 23, 2023 at 12:36 PM).

  • Impressed at how close to the real thing it was. I've flown over 4000 hours in the 135, though not much at that altitude (not too much crime to solve at 10,000').

    Have you practiced the landing in autorotation? Both engines at idle (or stopped)? Maybe on a professional simulator? Can she hover a bit before landing or not? Thank you in advance for your answer. :)


    In the simulator, you can take off carefully with both engines switched to idle. Is it like that in reality? (The low rotor rpm is beautifully programmed.)

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    Edited 2 times, last by Small Planes (August 23, 2023 at 5:16 PM).