Helicopter Flight Information

Attitude flying

Regardless of whether you are flying IFR or VFR, the attitude always comes first, and is then backed up by the flight instruments. There is a lag between a control input, and the reaction of the aircraft. This is especially true with regard to the airspeed, where there is about a 3-second delay from the time that a longitudinal (fore or aft cyclic) input is made, and the time that the airspeed begins to react.

Attitude, Airspeed, and Power

In order for a pilot to establish steady sate flight, it is necessary that he or she know the attitude and power setting that will achieve given airspeeds in given flight profiles. There are 3 important attitude, airspeed, and power combinations that should be well known to any helicopter pilot. These will be the climb/approach/autorotation attitude, airspeed, and power settings; the pattern cruise attitude, airspeed, and power setting; and the normal cruise attitude, airspeed, and power setting. With these known, it is easy to establish a steady state of flight in an instant by simply setting the appropriate attitude and power, then the airspeed and climb or descent profile will follow. These attitudes and power settings are not always published and it may be necessary that they be self learned, or taught. For students, the instructor may teach these profiles, and in many other situations the pilot may learn them him- or herself. 

To learn these given attitudes, a pilot must take note of something that will help them remember the position of the helicopter relative to the horizon. The compass may be directly on the horizon in a given helicopter while in straight and level flight, and in the same helicopter the pilot may note that in a normal approach profile, the compass may be below the horizon 2 inches, and so on. In some helicopters, it works well to note the tip-path-plane in reference to the horizon. A pilot may notice that in straight and level flight, the tip-path-plane is 12 inches above the horizon, and during a normal departure profile, the tip-path-plane is right on the horizon. If a pilot sets the known attitude and follows with a crosscheck of the instruments, he or she will find that the airspeed will be correct or very close. 

Power settings like the attitude will be constant for a given profile or phase of flight. For example in a Robinson R-22 helicopter, 24 inches of manifold pressure will be the appropriate departure/climb power setting. 22 inches will provide a good moderate cruise of about 78 knots, 19 inches will be sufficient to maintain a 60-knot pattern cruise, and 15 inches will be quite effective for the initial descent for a 10 degree approach profile. 

It is important to know these attitudes and power settings regardless of what you fly because the airspeed will lag behind these settings. If you try to go directly for the airspeed rather than setting the correct attitude, you will find yourself chasing the airspeed. Attitude flying is equally as important in fixed wing aviation as well. 

Steady state flight

Regardless of the maneuver, achieving a steady state flight condition as early as possible is the primary goal. Once a stabilized flight condition is achieved you can relax somewhat, and then flying becomes much more fun. If you are not in a steady state of flight you will be hunting various things like manifold pressure, airspeed, and throttle position and you will certainly be unable to relax. As a pilot’s experience progresses his or her ability to achieve a steady state of flight increases until it is natural and without thinking they are always in a steady state. Often these pilots wonder as they look back why they had such a hard time in the first place. 

Over Controlling

Whether flying airplanes or helicopters, over-controlling the aircraft is a problem for all student pilots. Even a highly experienced airplane pilot adding-on a helicopter rating will have over controlling problems when learning to fly helicopters. The largest contributing factor to this condition is the fact that these pilots become tense on the controls, especially in gusty winds. This tense condition causes increased over-controlling, and then the pilot becomes even tenser because the helicopter is not doing what he or she wants it to do. In reality the helicopter is doing just as the pilot tells it, he or she makes an input and the helicopter responds. If his input was not stable, the helicopter response will not be stable either. Think of when you were learning to drive a car, you were tense and all over the road but when you relaxed the car became easy to control. The helicopter is no different but it is much much more responsive. 

This over-controlling uses excessive energy, both of the pilot and of the helicopter. For example; over-controlling the cyclic in a hover blows the air cushion of ground effect out from under the rotor disk requiring more power and consequently more throttle to maintain a given hover height. Often on take-off a pilot pulls too much collective initially and then less collective must of course follow and then he or she is constantly chasing the collective and throttle. For the pilot, the tense condition takes its toll by fatigue, and the pilot is completely worn out in less than 2 hours. 

Departures 

During all departures, the collective should be smoothly raised to the desired manifold pressure, and the throttle should be set so that the rpm is in the top of the green arc. Once the desired manifold pressure is achieved, and the throttle is set, the collective and throttle can be effectively held in position until a change is desired for cruising flight. The collective and throttle will not change if the pilot does not either move them or let them move. 

For collective stability it helps to rest a finger or your thumb against your leg to hold the position or to get a position reference. This also helps to locate a position when a collective change is necessary because it feels familiar; a given position achieves a given manifold pressure for a particular phase of flight. 

The cyclic can also be held relatively still. When you input the proper cyclic, in most cases it will not be necessary to noticeably move it because it will remain relatively steady. 

Cruising flight

During cruising flight, as in a departure, the collective and throttle rarely need to be moved. Once you have set the desired manifold pressure and the throttle is set to the top of the green, take a position of reference with a finger or thumb and maintain this position until a change is necessary. Perhaps it will be effective to rest your wrist against your leg. Although the collective friction works well to hold the collective in position on some helicopters, do not use it as a cruise control. If you think you have time to get the collective down in an emergency from a relaxed position on your lap you are in for a surprise, but you won’t likely know it. Be a pilot, fly the aircraft. 

Although the cyclic is constantly being manipulated during all phases of flight, there is very little movement during steady state stabilized flight. Of course this is different in turbulent conditions in cruising flight, and while hovering in windy conditions. However as a rule in normal conditions, if you can see cyclic movement it is usually excessive. 

Approaches

Regardless of the approach to be executed, the proper manifold pressure and attitude should be set and maintained as previously mentioned until a change is necessary for the final approach or as the termination is neared. During a normal approach, the initial attitude will be constant through 300 feet where the focus is changed to the landing zone, and then the final approach attitude should be set, and the manifold pressure should be reduced another 2 inches or so. When the correct attitude and power settings are known, there will be little or no hunting. 

Autorotations

Upon the entry to an autorotation, the collective should be placed securely down, and then raised only to capture the rpm where it is desired. Once the rpm is stabilized, movement of the collective should not be necessary again until the termination of the autorotation. The cyclic should be moved to set the proper attitude for the desired airspeed in the descent, and then held steady capturing the airspeed. There is a tendency for most pilots to move the cyclic aft as the helicopter descends through about 300 feet AGL. This should be avoided, because it introduces a hunting condition at the critical phase of the descent. The airspeed should remain steady until the initiation of the flare (see chapter 20). 

Focus

With the exception of normal instrument and traffic scanning which should be maintained, a student pilot’s focus should be concentrated straight ahead of the helicopter as if he or she had a neck brace on and could not turn his or her head. The student should learn to sweep the line of sight with the aircraft. This sounds contradictory to scanning, but that is not the case. In a hover this will help point the helicopter in the right direction. Think for example that the pilot is focused on the taxiway centerline. The helicopter yaws this way and that, and the pilot never recognizes that the track is not true with the centerline because he or she never took their eyes off the centerline. If their head were frozen forward, they would have recognized this yawing problem, and learned to step on the pedal to correct it.  

This problem occurs with students when they are in altitude flight as well. The instructor tells the student to turn right 90 degrees, and the student checks to the left and then to the right for traffic, and rolls into the turn. The nose of the helicopter begins to sink, and the student never notices it because he or she is still looking where they want to go (to the right). Instead, the focus should have been returned straight ahead so the correct bank attitude could be established, and then the normal scan resumed. 

It is important in helicopter flight training for students to learn of their peripheral vision capabilities. Like other senses, this sense can be sharpened and must be learned so that a total awareness of the surroundings always exists. In the early phases of flight training, students often do not understand how anyone can see anything peripherally, but it is soon understood after consistent practice.  

Once a pilot gains experience these factors are no longer an issue, but it is quite important in the early stages of flight training in the helicopter.  

Anticipation

Learning to anticipate what the helicopter is going to do is the hardest part of mastering the helicopter. When a pilot is first learning to fly the helicopter their control inputs are about 2 or 3 times as much as they need to be and they are usually much to late. The pilot fails to recognize what control input the helicopter actually needed to achieve the desired results, and when he or she makes the input it is excessive and late. This is normal for students, and there is no way to avoid this and other factors and conditions that are part of the learning process.

Student pilots must learn to recognize the first sign that the helicopter is going to move, and a small control input should be made at that time. This can only be achieved by looking out in the distance while peripherally noticing the attitude changes of the helicopter. Once an attitude change is detected, the pilot must know exactly how much input is needed, and make that input before a more extreme input becomes necessary.  

Control feathering

When it is stated that a control input must be made, students must understand that most commonly, these inputs are very slight. This means so slight that you may not be able to see the input, and actually you will be feathering the controls from their desired positions.  

For example, if the desired hover height is 3 feet, this height will be set, and the collective will be feathered from that point, maintaining a 3-foot hover. Likewise, if a stationary hover is desired, the cyclic will be feathered from the stationary hover neutral position, maintaining a fixed position above the ground. If a forward taxi is desired, a very slight forward cyclic input will be made to establish forward movement, and this will be the new neutral position, and the cyclic will now be feathered from this position to maintain the desired taxi speed. In a manual throttle helicopter, the throttle will also be feathered from the appropriate setting.  

This is not to say that the control inputs are always just feathered; there will be times when a quite noticeable input must be made, but this is the exception, not the rule. ☺

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Last modified: 12/31/2011