Description
This manoeuvre consists of 2 consecutive inverted backward loops that should be entered from inverted backward flight.

Preparation
Before attempting a backward inverted loop. It is important to be totally familiar with backward inverted flight at various speeds. I would recommend performing a few conventional upright backward loops to ensure familiarity of backward flight. In addition, I would suggest practice of some backward flips that offer the opportunity to practice the basic control inputs required to perform the backward inverted loop.

The diagram illustrates the manoeuvre that is entered from level inverted flight (bottom entry). The loop is started with back cyclic and negative pitch to enter the climbing section of the loop with these controls being carefully balanced to ensure a smooth climb to the vertical as shown. From here pitch is changed through 0º to a positive value as the model goes over the top of the loop, with continued application of back elevator to retain backward motion. Collective pitch is progressively changed back through 0º as the tail-down vertical section is reached. From here, negative pitch is slowly introduced and balanced with back elevator to ensure a smooth exit back to level inverted flights. You will have noticed that the overall manoeuvre requires ‘2 consecutive inverted backward loops,’ so after you have mastered single examples have a go at 2 loops.

The exit from your first loop is the start of the second. Try not to hesitate and take care to retain speed into the second loop.

Possible Problems
Speed retention during the first half of the loop often presents problems. It is important to start with a sufficiently high entry speed and take great care not to enter the climbing section of the loop too abruptly. If this happens, speed is lost very rapidly resulting in the model struggling over the top. To assist the climbing part of the loop the ‘tail-down’ entry attitude should be retained during this critical section of the loop to enable negative pitch to assist this upward motion towards the top of the loop. The diagram illustrates this with approximate pitch values included. The descending part of the loop should be carefully flown to avoid an abrupt change of direction as the speed builds towards the exit point. A smooth flowing exit is necessary to score well, and also to retain plenty of speed leading to the second loop.