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 backBack to Set Manoeuvres List    Travelling Backwards Flip

Travelling Backwards Flip

Description
The model should be flown forwards at medium speed parallel to the flight line and a backward flip performed that should be timed to centre in front of the pilot as shown in the Diagram. The model should enter and exit the manoeuvre at constant height and speed with good directional control throughout.

Preparation
This should begin by checking your backward flips, initially stationary and at a safe height. Begin the backward flip with a smooth application of back elevator. As the model approaches the nose-up position collective pitch must be reduced to zero. Pitch is then changed smoothly to negative to maintain height during the inverted section. With a steady back elevator input held in pitch is then changed to zero as the second knife-edge position is reached with the nose down and this followed with a positive pitch increase and reduction of back elevator to bring the model back to a level hover. Practice of these stationary flips should continue until you are producing smooth and accurate examples that retain height and heading.

The next step is to introduce a little forward speed as the flip is entered. Initially perform the flip as before and observe the results. At very low forward speed you will notice very little change but as the entry speed increases it will become apparent that during the flip most of this speed will be lost. To overcome this collective pitch must be used during the time the rotor disc is at or near the vertical knife-edge positions to drive the model on and ensure a sufficient exit speed. This translates to a few degrees of negative pitch during the first (nose up) knife-edge section and a similar amount of positive pitch during the second (nose down) section. These pitch changes must, of course, be introduced in a smooth manner to produce the desired overall result of an accurate backward flip that retains forward motion to ensure equal entry and exit speed.

Possible Problems
These usually centre around incorrect pitch control through the flip. Accurate, smooth inputs are required to produce the best results. Elevator control is much less of a problem as the best results are produced with a consistent rotation through the flip that requires a steady elevator application. Only the timing of the start and finish of the flip requires precise elevator control and this should soon be perfected with practice. It is important not to rush the flip but to make a conscious effort to slow down the manoeuvre as much as possible. The aim is to produce a flowing manoeuvre as shown in the diagram that retains both height and speed throughout. Wind direction may pose some problems especially if you are only able to fly the travelling flip in one direction. If this is the case I would recommend practicing with wind from both your left and right sides. With a tail wind less pitch corrections will be required during the knife-edge positions and with a headwind these corrections will require emphasising to maintain forward speed.

 

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