RADIO CONTROL HELICOPTERS
Paul Tradelius, 4620 Barracuda Dr., Bradenton, FL 34208
In my last few columns I discussed techniques to consider prior to hovering, and techniques to consider as you proceed from hovering to more advanced maneuvers. This seems to be a good time to pay more attention to the basic helicopter maneuver—the hover.
One aspect of helicopters that I have always enjoyed is that pilots learn from the ground up. With wide training gear attached to the helicopter, the learning process starts by bouncing the helicopter around the flying field, followed by longer and more controlled hops off the ground. Then it isn't long until beginners feel that they really have control, and they can hold the model in some degree of a hover for an indefinite period of time. They have arrived at, and have mastered, the hover.
Many fliers quickly forget about hovering because they are more concerned with progressing to forward flight and aerobatics. That's natural, because a helicopter hovers at liftoff, again prior to landing, and that's all of the practice many pilots need in a normal day of flying. That is the level at which most fliers find themselves; they are competent and they have hovering ability equal to that of others at the flying field. However, there is another hovering plateau to be reached if you want to enter a contest, or if you just want to improve.
Look closely: the difference between good and excellent
To improve hovering, one of the first things you must do is really look at your helicopter. This may sound obvious, since you look at your helicopter while it's flying, but you may not be looking closely enough. The average pilot makes a control input when the helicopter moves slightly out of the desired hover position, with the idea of bringing the helicopter back to its original position. That is normal—it is the way you learned to hover. But no matter how the hovering process is described, the helicopter had to move before a control input was made. The real difference between a good pilot and an excellent pilot is how far the helicopter gets out of its hover position before a correction is made.
The hovering process reminds me of the many years I spent in the Air Force flying fighters, some of which I spent teaching formation flying. The idea is for the wingman to maintain a specific position relative to the flight lead. Maintaining position is hard to do when learning, so the wingman is flying in a large "bubble," and he is trying to refine his control movements to reduce the size of this bubble.
Formation-flying techniques (and how they apply to hovering)
The wingman has to understand and master several formation-flying techniques:
- Know immediately when he is out of position. This requires concentrated attention on the flight lead so deviations are detected at once.
- Make an immediate and aggressive control input to prevent getting farther out of position and to start moving back into the correct location.
- Perfect the technique in all three axes to maintain a specific position.
You might have seen great displays of formation flying; most people don't realize that the wingmen are never in perfect position, but they are always striving to get there. A new formation pilot may be striving to maintain a 30-foot bubble, while a good formation pilot can maintain a three-foot bubble, and a Thunderbird pilot can maintain a one-foot bubble.
Helicopter pilots must use these techniques to fly formation with the ground. Knowing immediately when you are out of position takes a great deal of concentration. When hovering, pilots must constantly look for the slightest change in helicopter attitude, which will produce a change in hover position.
Detecting small attitude changes and correcting aggressively
Assume that the helicopter is in a good hover position, and (for whatever reason) the nose dips slightly. That causes the lift vector to be tilted forward slightly, which acts to move the helicopter.
For instance, if you have a 10-pound helicopter, the lift of the rotor system must also be 10 pounds to maintain altitude. A one-degree nose-down movement produces a forward thrust vector of 0.175 lb of force. Even that small force will move the helicopter, if left to act over a finite period of time. But if the pilot can immediately see the change in pitch attitude and make an immediate correction, the helicopter will remain in the desired hover position.
That is why I believe Curtis Youngblood hovers so well; he detects when his helicopter is slightly out of the desired hover attitude, then makes an immediate, aggressive correction, with almost disregard for smoothness, because the smallest resulting force takes effect first. Curtis's competitors appear to let their helicopters get farther out of the desired hover position before making a control input, and even then they are more concerned with smoothness of control, so the helicopter is out of position for a longer period of time.
One of the first things that you will notice if you try to apply these principles is that you will be mentally drained in a very short period of time. It takes much concentration to see a small movement, make a control input, then start the process again, all the time striving to see the helicopter better so that you can make more (and quicker) control inputs.
Most fliers don't care to put this much effort into improving their hovering, so they accept a larger "bubble," which applies to every maneuver they fly. Ask yourself, "Am I really in the position I want, or am I just close enough?"
Transcribed from original scans by AI. Minor OCR errors may remain.
