Mastering nose-in hovering

Model Airplane News, Sep 2000 by Bell, Rick

In previous issues, we've discussed the basics of hovering and forward flight, and you have at last reached the point where you have mastered the tail-in hover. You are beginning to feel "one with the machine," but you are also aware that this togetherness can literally turn around on you. You're not quite one with the machine yet. It is no secret that to become a proficient heli pilot, you must team nose-in hovering. Descents out of forward flight, pirouettes and autorotations all require nose-in skills. If you are a proficient fixed-wing pilot, then you understand how a plane reacts to stick inputs when it's flying toward you, and you will have an advantage learning nose-in heli flying; this advantage, however, applies to forward flight only. During nose-in hovering, three of the controls seem reversed, but of course, the controls are still the same to the heli. No matter what your orientation is, left is still left to the heli. The confusion comes from the fact that you have been practicing very hard to hover the heli from behind, where control inputs match the reaction of the heli. So the question becomes, "When and how do I Team nose-in hovering?" The first part of the question is easy to answer: as soon as you can comfortably hover tail-in. The second part of the question is more difficult, as there are various ways to learn nose-in hovering: starting from the ground up; starting from a 90-degree hover; and starting from forward flight. Each has its advantages and disadvantages, and I'll describe them, beginning with the way I learned myself.

FROM THE GROUND UP

This is just like learning to hover tail-in all over again. You'll have to pull out that training gear you thought you wouldn't need anymore. Strap it back on, and remember how you learned to hover tail-in. You started by getting the heli light on the training gear and exercising the cyclic controls and the tail rotor. This will be no different. The process is the same, except you start by looking at the nose of the heli. Begin by facing the nose of the heli into any wind. Actually, a little wind is good, as it will help stabilize the tail. Stand at least 20 feet back from the nose (for safety), and slowly feed in throttle until the heli starts to get light on its SkidS. Now play with the controls, and note the reactions. As you move the roll cyclic to the right, the rotor disc tilts to your left, and a left cyclic command tilts the rotor disc to your right. Now move the cyclic fore and aft. A forward command tilts the rotor disc toward you. Unnerving, isn't it? You have to learn to look at the heli in new ways.

First, consider the tail rotor. You could fly the tail rotor as if it were the nose; the tail-rotor pitch will now respond as if the heli were hovering tail-in; e.g., a right-stick command will move the heli's tail to the right. By "reversing" your concept of the heli, you've made pitch control familiar once again. An even better method is to think of the whole heli as rotating either clockwise or counterclockwise. No matter which way you look at the heli, a right tail-rotor command rotates the heli clockwise-it doesn't matter whether it's nose-in or tail-in (Figure 1). Once you've mastered nose-in pitch control, it's time to consider the cyclic. The key idea with cyclic control is to use counter commands. If the heli starts to drift, for example, to the right (your right), push the roll cyclic to the right. In reality, the heli is moving to its left and you've just given a right command to counter the drift (see Figure 2). Simple, isn't it? The same goes for the forward/aft cyclic. If the heli moves toward you, pull the cyclic toward you. Again, you're giving a counter command to stop the movement. In other words, move the control stick in the same direction the heli is moving to check its motion. Once you have a feel for the controls, increase throttle until the heli is a few inches off the ground. Remember that the lack of altitude is your friend. Briefly hold the hover and land. Keep extending the time your heli is airborne until you can hover out a full tank, just as you did for tailin hovering. Your learning curve should be shorter this time because you already have hovering skills.

STARTING FROM A 90-DEGREE HOVER

Begin by hovering the model at a 90-degree angle to yourself so you're looking at the heli's side. You should be able to do this fairly well by now. Again, be sure to keep a reasonable distance between you and the heli. Now apply tail rotor to turn the nose of the heli toward you (10 or 15 degrees should be enough to make you nervous). Try to hold the heli in this position until it becomes easier to do. When it has, add another 10 to 15 degrees of movement so the nose of the heli is pointing more toward you. Practice holding this position until you feel comfortable, then rotate the heli a few more degrees and hold. Keep rotating the heli toward you in small increments until the nose is fully facing you. This is an easy way to become experienced with the reversed controls. Be sure that once you can turn the heli toward yourself from one direction, you also practice turning the hell toward you from the other side. In other words, if you first learn by looking at the right side of the heli, try learning the maneuver from a position where you begin by looking at the left side of the heli. Another variation is to start from the ground up using training gear.