Inverted

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Inverted is an orientation where the helicopter is helicopter flown upside-down, intentionally and without crashing. By using good collective management, and either an aileron or elevator input, the helicopter can flip nicely to a inverted state.

Only collective pitch helicopters are capable of more than momentary inverted flight; for sustained inverted flight the blades rotate along their length (applying negative collective pitch); essentially reversing the direction of the airflow through the main rotor.

When flying inverted, the elevator, rudder, and collective controls will appear to be reversed. The 'old school' way of coping with this was to have a switch on the transmitter which reversed those controls electronically, allowing the pilot to continue to fly the helicopter as if it were the right way up. This method is generally no longer used as when the pilot transitions into 3D experience flying 'switched' will be a positive liability; it is better simply to learn the inverted orientations until they become as instinctive as the upright orientations.

Tips

  • Before trying inverted, it is recommended that you practice on a simulator.
  • Make sure you have sufficient negative pitch available, and your idle up mode setup gives you plenty of throttle when you use negative pitch, using (for example) a V shaped throttle curve. Make sure you select idle up before you go inverted!
  • You should ensure that your swashplate is level, and that you do not have large amounts of trim applied to compensate for poor weight balance. If you do, the error will be applied, double, when you are inverted.
  • Make sure your throttle hold is configured to cut the engine, and practice using it in an emergency on the simulator. With idle up selected, just moving the collective control to the bottom will apply full throttle, which is not good for you helicopter as it does the funky chicken on the ground.
  • You can take your first cracks at inverted by extending the inverted phase at the top of a loop. As you become comfortable with this, you can extend it into a split S. Many people start by performing half flips, but a nice flip is in itself a relatively difficult maneuver.
  • The inverted collective control usually comes quite naturally. The reversed rudder can be accommodated by thinking about controlling the helicopter's tail (or point nearest to you) rather than it's nose (or point farthest from you).
  • The elevator reversal is hard to learn. There are two mnemonics I found useful.
    • PUSH UP, PULL DOWN: Looking at the nose, pushing the stick up will push the nose up, and pulling down will pull the nose down.
    • TOWARDS DISK, AWAY FROM DISK: Pulling the elevator towards you will move the nose towards the disk, and vice versa. This has the advantage of working in any orientation, including upright.


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