This is an impressive 3D maneuver, and while you’re learning, it’s important to break it down into short segments. Before you attempt it, make sure that you are proficient with rolling at a fairly fast roll rate. Second, make sure that you know how to perform a typical tumble. Let’s start by refreshing your memory on the tumble.
Begin by pulling your model onto a 45-degree upline at a significant altitude. Then, switch your model to your high-rate setting (for the aileron, elevator, and rudder control surface) and apply down-elevator and the same direction rudder and aileron. For example, to perform a tumble to the left, add down-elevator, left aileron and left rudder.
To perform the rolling tumble, you must fly to a fairly high altitude and parallel to the runway. Once you’ve established this flight path, fly the model at a moderate flight speed then begin rolling the airplane. On average, after every roll is complete, apply the inputs for a tumble (in the same direction of the roll). Aileron input should always remain fairly constant, as the model should not stop rolling even after a tumble is complete. When you want to finish this maneuver, simply stop the model’s roll when the wings are level relative to the horizon to exit in an upright manner.
FIRST THINGS FIRST
As I mentioned before, it is very important to become proficient with rolling quickly while maintaining the same heading. Simply said, the model should track as if it were on a string from one end of the flying field to the other while rolling. Throughout this maneuver, maximum control deflection on the rudder surface will be used, and to ensure success in performing this maneuver, you should be aware of the proper implementation of 3D rates. This is another way of expressing rate values with maximum control surface deflection (+/-45 degrees of deflection). While extreme amounts of aileron and elevator deflection are not critical for this maneuver, the rudder deflection is. When using 3D rates, I highly recommend that you use a lot of exponential on a control rate that’s above 30 degrees of deflection. A value of 60-percent expo will ensure that your model is fairly precise around neutral stick and your extreme endpoint value will be obtained when the control stick is at its maximum point. Exponential is an adjustment to the actual curve of how the inputs are given to the servo. By using a greater amount of exponential on high rates, your model will react the same way it does on low rates when the stick nears center.
To successfully perform this maneuver, a model with excessively large control surfaces is not needed, but is preferred. Also, always remember that the difference between a good-flying aerobatic model and a great one is in the design of the aircraft. Models with a fairly light wing loading and a high power-to-weight ratio are usually better-flying models. Now let’s discuss the five steps to performing this show-stopping maneuver!
FLYING THE ROLLING TUMBLE
This maneuver requires that you establish a flight path that is parallel to the runway at a fairly high altitude. If you become disoriented, a safe recovery will be possible. Remember, this is a fairly complex maneuver and some models may react differently to the control inputs that are needed to successfully perform this maneuver.
- To begin, use a moderate throttle setting and make sure that your model is on high rates for all control surfaces (aileron, elevator, and rudder). Then, begin rolling your model to a particular direction. In this example, we will roll the model to the left.
- When the model is in the inverted position (for example, once the model performs 1 1/2 rolls from upright level flight to inverted flight), you’ll need to apply full down-elevator and full left rudder (if the model is rolling to the right, apply right rudder). If done properly, the model will perform a tumble.
- Remember that the model should never stop rolling. With that said, always keep the aileron input fairly constant. Once another roll is complete, perform another tumble.
- Remember that different models will perform this maneuver differently. If you input too much down-elevator, the model may perform a maneuver that looks like a positive gyroscopic maneuver. Do not mistake this for a tumble. If your model exhibits this, use less elevator input.
- To exit the maneuver, you can either continue rolling or stop when the wings are level relative to the horizon in upright level flight. Now your mission is accomplished! Give it another shot, as practice makes perfect.
These five steps are the basics to performing the rolling tumble. Time and time again, I urge you to never become discouraged when trying a new aerobatic maneuver. If you are finding this maneuver difficult to perform, I urge you to review your plane’s setup. For example, does your aircraft roll too fast and you can’t apply the needed inputs to maintain proper heading? If so, decrease your aileron travel rate (in other words, decrease your dual rate value). Above all else, always remember to have fun!
BY JOHN GLEZELLIS