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Tumbling Loop

Description
The model should perform a Forward or Backward Loop whilst executing Forward or Backward tumbles. The loop should be centred and the rate of tumbling must be uniform.

Preparation
This should begin with checking your looping skills. During the tumbling loop, your model will be alternating between forward and backwards flight so I would recommend you practice both forward and backward loops before proceeding further. Take time to ensure you can perform accurate examples consistently of the size you intend to use for the tumbling loop.

To develop ‘tumbles’ begin by checking your stationary flips. Try both forward and backward flips to determine your preference. It is important to develop smooth flowing flips that are not rushed. Steady elevator input should be held in whilst pitch is changed smoothly from about +5º with the model upright to zero at both knife-edge position and about –5º during the inverted section.

Practice until you are able to hold position with at least 10 continuous flips in your desired direction. The next step is to introduce some speed (forward or backward) as the flip is entered. Initially, keep speed low and flip 2 or 3 times. From here, slowly build entry speed and begin to introduce collective pitch during the ‘knife-edge’ sections of the flip to ensure the model is driven on in the desired direction. It is important at this time to check your flips are smooth and as slow-as possible to give you plenty of time to introduce the necessary pitch variations. Once you are able to accurately control 2 or 3 moving flips and retain motion well the next step is to slowly increase the entry speed with the aim of maintaining this through a few flips. You will now notice how important pitch control is as more emphasis must be placed on the knife-edge sections to maintain overall speed.

From here we should now begin to attempt your first tumbling loop. You should now be happy with the tumbling entry but to begin the upward part of the loop will require your pitch change emphasis to shift from the rotor disc knife-edge position to the rotor disc horizontal position at the quarter loop point. The diagram illustrates approximate pitch values at various points of the tumbling loop.

Your first tumbling loop attempts will probably produce some odd shapes but try to keep the model tumbling as long as possible. Once you have achieved a full tumbling loop time must be spent working on accuracy to produce a round loop with consistent speed and tumbling rate throughout.

Possible Problems
Producing a round tumbling loop with consistent tumbles and speed throughout requires considerable practice. There is a temptation to allow your flips to become too fast with the result that accuracy suffers. A conscious effort to slow down the flip rate is often required to give you the chance to time pitch inputs correctly at various points of the loop. The descending section of the loop again requires careful reduced pitch control to maintain a constant overall speed.

 

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