Tuesday, December 12, 2017
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Beyond Basic Hovering

Beyond Basic Hovering
Figure 1: Initiate forward flight with a brief bump of elevator immediately followed by an opposite bump to prevent the heli from moving too quickly. Nudge the throttle to control height and apply tiny aileron and elevator bumps to manage speed and direction while using the rudder to keep the nose pointing in the direction of flight. Coordinate small amounts of aileron and rudder to initiate the turn, then pull elevator to keep the turn level while adjusting the rudder to cleanly carve around the turn.

This month, 1st U.S. R/C Flight School’s progressive helicopter training series enters a new phase of more challenging maneuvers aimed at raising the sense of accomplishment for pilots who have recently become comfortable with basic maneuvering while hovering. As always, it’s presumed that these lessons will be practiced on a simulator prior to flying in the real world, and the control techniques described apply primarily to flying collective (adjustable) pitch helicopters, but will generally work with single rotor fixed pitch helis as well. And as always, in the interest of simplifying the text, the control applications will be described using the customary airplane terms aileron, elevator, and rudder.

FIGURE 8’S AND S PATTERNS
The previous articles in this series detailed the techniques required to maintain straight lines and perform forward flight procedure turns. The two maneuvers that consolidate those skills are elongated figures 8’s and S patterns (figure 1). Start by using the rudder to point the nose in the direction you wish to fly, then initiate forward movement with a small brief bump of elevator immediately followed by an opposite bump to stabilize the movement. Briefly bump the right control stick to fine tune the speed and direction of the movement, use the rudder to keep the heli pointing in the direction of flight, and continue nudging the throttle to maintain the same height. Remember to watch the body or “heli as a whole” to determine the direction of the movement rather than watching the rotor disk since the
rotor disk isn’t always an indicator of the actual flight path.

When the heli nears the edge of your comfortable viewing area, initiate each procedure turn with small amounts of rudder and aileron, followed by pulling elevator. Continue to hold in and adjust the rudder (and sometimes aileron) to cleanly carve around the turn without skidding. I.e., add more rudder when the nose of the heli points to the outside of the turn, and reduce the rudder when the heli skids into the turn. Also continue adjusting the elevator to keep the turn level. However, if an attempt to arrest a descent by pulling more elevator doesn’t produce immediate results, add more power as well. Then exit the turn by removing the rudder and elevator and applying opposite aileron to return to level.

When you can routinely perform figure 8’s and S patterns, and you’ve previously become proficient at hovering nose-in, the next phase of maneuvers will be much easier.

STATIONARY PIROS
At this point, you may want to add a steady wind into your simulator and practice holding in rudder to perform multiple pirouette rotations or “piros” while bumping aileron and elevator into the wind in order to remain over the same spot (figure 2). Example: During a tail-in hover in a right-to-left crosswind, you’ll need to bump or hold right aileron against the wind to prevent wind drift. When you start to pirouette, briefly pull elevator when the tail points into the wind, briefly bump left aileron when the other side is exposed to the wind, and push forward elevator when the nose points into the wind, etc., etc. Note that the amount of time that the sides, nose, and tail are exposed to the wind is quite brief during continuous piros, thus the aileron and elevator bumps need to be brief as well, i.e., “in-out”. If some or all of the bumps force the piro out of position, it’s possible that the timing is off, but most likely the bumps are too large or held in too long. You’ll also discover that the corrections do not need to be very large to correct for even a strong wind.

Beyond Basic Hovering
During counter-clockwise piros in wind, continually apply brief bumps to tilt/lean the heli slightly into the wind: Bump right aileron into the wind at the start; briefly pull elevator into the wind when the tail faces the wind; bump left aileron when the other side faces the wind; then briefly push elevator when the nose faces the wind. All together: Bump right, pull bump, bump left, push bump. Repeat.…

360’S AROUND A POINT
The first two maneuvers that most pilots learn beyond the basics are 360 degree circles with the nose or tail pointing at the center of the circle throughout (figure 3): Start with the nose or tail pointing at center box, then initiate movement to the side with a small brief aileron bump immediately followed by an opposite counter bump to keep the movement from escalating. The nose-in version then requires you to hold rudder in the opposite direction of the movement to keep the nose pointing at the center of the circle all the way around. A tail-in circle requires you to hold rudder in the same direction as the movement. Tiny aileron bumps are used throughout to manage a slow steady side movement, while tiny elevator bumps are used to maintain the same distance from the center of the circle.

Beyond Basic Hovering
Counter-clockwise nose-in circle: Start with the nose pointing to the inside of the circle. Input a small brief bump of right aileron to start moving sideways immediately followed by an opposite left aileron bump to prevent the movement from escalating. Hold in left rudder to keep the nose pointing at the center of the circle, push and pull elevator to maintain the same distance from the center of the circle, and make tiny aileron adjustments to control the speed of the side movement.
Beyond Basic Hovering
Counter-clockwise tail-in circle: With the tail pointing at center box, bump left aileron to start moving sideways immediately followed by an opposite right bump to prevent the movement from escalating, then hold in left rudder to keep the tail pointing into the center of the circle. Push and pull elevator to maintain the same distance from the center of the circle while making tiny aileron adjustments to control the speed of the side movement.

The single most important thing that you can do is try to keep all your inputs tiny and brief. Indeed, you can even go the wrong direction multiple times without getting into serious trouble as long as all your inputs remain brief.

The secret to performing this maneuver with less confusion is to lock in the rudder input in order to concentrate on controlling the pace of the sideways movement with the aileron while pushing and pulling the nose toward and away from the center of the circle to maintain the same distance. At some point you’ll also learn to adjust the rudder to keep the nose pointed precisely at the center of the circle throughout, but initially concentrate on the aileron, elevator, and throttle adjustments needed to complete the circle.

BACKWARD FLIGHT
Flying backwards is a great exercise that will make everything else that you’ve done up to this point seem simple by comparison (figure 4). Until you attempt to turn, the techniques used fly backward are no different than when you backed up the heli while hovering, except you’ll be flying backwards for longer periods and possibly faster. Start: Initiate backward flight by briefly pulling back on the elevator and then apply an opposite counter bump to stabilize the movement while adding power to maintain altitude. Control the speed of the backward movement by briefly pulling elevator to speed up and pushing forward to slow down. As usual, control the flight path with aileron, keep the body/nose straight with the rudder, and adjust the throttle/collective to maintain the same height.

The simplest approach to performing a turn while flying backwards consists of using the rudder to turn the nose away from the direction that you want to turn, thereby pointing the tail into the turn. Next, nudge the aileron to bank slightly into the turn, then keep nudging the aileron as needed to carve a steady arc around the turn. Since these are slow speed turns at first, altitude during the turn is controlled with the throttle/collective, and the elevator is used exclusively to control the pace of the backward movement.

Beyond Basic Hovering
Enter a moderate speed backward turn by turning the nose away from the direction you wish to turn; then nudge the aileron to bank into the turn. Lock in the rudder and continue to adjust the aileron to maintain a slight bank and gradual carving turn. Control the speed of the backward movement with brief elevator bumps.

The secret to backwards turns is to lock in the rudder input so that your attention can be concentrated on controlling the pace of the backward movement and bumping the aileron to carve a nice arc. You will inevitably apply the aileron in the wrong direction, therefore it’s vital that you keep all your aileron inputs very tiny and operate by the rule that if one bump isn’t enough, you can always apply another.

CONCLUSION
Real world success at this level will reflect the effort put in on the sim beforehand and whether your basic foundation is solid enough for steady advancement. Those who struggle to achieve success at this level most likely need to spend more time working on the basics. Thankfully, simulators are so realistic today that if you can do it in the simulator, you can be confident that your success will translate to the real world. Good luck.

Words and Illustrations: Dave Scott

One comment

  1. Warren Thompson

    I filled out the form to win a Red Bull Model , Autographed by Chuck Aaron and never did see if or who might have won it. One of the guys in our RC helicopter club, Virginia Fliers, built a scale Red bull but crashed it, If I had won , I was going to give it to him, I just love your mag and always has some very interesting things that help keep my birds in the air. I was trying to find an address to get ahold of Chuck Aaron but couldn’t find any. Thanks . Warren Thompson

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