Weight-Shift Control Aircraft Flight

Rejected Takeoff/Engine Failure in Weight-Shift-Control Aircraft

Filed Under: WSC Takeoff and Departure Climbs

Emergency or abnormal situations can occur during a takeoff that requires a pilot to reject the takeoff while still on the runway. Circumstances such as a malfunctioning powerplant, items dislodging during takeoff, inadequate acceleration, runway incursion, or air traffic conflict may be reasons for a rejected takeoff.

Prior to takeoff, the pilot should have in mind a point along the runway at which the aircraft should be airborne. If that point is reached and the WSC aircraft is not airborne, immediate action should be taken to discontinue the takeoff. Properly planned and executed, chances are excellent the aircraft can be stopped on the remaining runway without using extraordinary measures, such as excessive braking that may result in loss of directional control, damage, and/or personal injury.

In the event a takeoff is rejected, the power should be reduced to idle or the engine shut off and maximum braking applied while maintaining directional control. If it is necessary to shut down the engine due to a fire, the fuel supply should be shut off and the magnetos turned off. In all cases, the manufacturer’s emergency procedure should be followed.

What characterizes all power loss or engine failure occurrences after lift-off is urgency. In most instances, the pilot has only a few seconds after an engine failure to decide what course of action to take and to execute it. Unless prepared in advance to make the proper decision, there is an excellent chance the pilot will make a poor decision, or make no decision at all and allow events to rule.

In the event of an engine failure on initial climb-out, the pilot’s first responsibility is to maintain aircraft control. At a climb pitch attitude without power, the WSC is at or near a stalling angle of attack. It is essential the pilot immediately lower the pitch attitude by pulling the control bar back to the chest immediately to prevent a stall. As discussed earlier in the climb section, a preventative measure is to climb to a safe altitude, 200 feet was used as an example, at least the minimum safe climb speed as recommended by the manufacturer to lower pitch angle as a safety measure for this situation to minimize a high pitch angle close to the ground. The pilot should establish a controlled glide toward a plausible landing area (preferably straight ahead on the remaining runway).

Noise Abatement

Aircraft noise problems have become a major concern at many airports throughout the country. Many local communities have pressured airports into developing specific operational procedures that help limit aircraft noise while operating over nearby areas. For years now, the Federal Aviation Administration (FAA), airport managers, aircraft operators, pilots, and special interest groups have been working together to minimize aircraft noise for nearby sensitive areas. As a result, noise abatement procedures have been developed for many of these airports that include standardized profiles and procedures to achieve these lower noise goals.

Airports that have noise abatement procedures provide information to pilots, operators, air carriers, air traffic facilities, and other special groups that are applicable to their airport. These procedures are available to the aviation community by various means. Most of this information comes from the Airport/Facility Directory (A/FD), local and regional publications, printed handouts, operator bulletin boards, safety briefings, and local air traffic facilities.

At airports that use noise abatement procedures, reminder signs may be installed at the taxiway hold positions for applicable runways. These are to remind pilots to use and comply with noise abatement procedures on departure. Pilots who are not familiar with these procedures should ask the tower or air traffic facility for the recommended procedures. In any case, pilots should be considerate of the surrounding community while operating their aircraft to and from such an airport. This includes operating as quietly, yet safely as possible.

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Soft/Rough Field Takeoff and Climb in Weight-Shift-Control Aircraft

Filed Under: WSC Takeoff and Departure Climbs

Takeoffs and climbs from soft fields require the use of operational techniques for getting the WSC aircraft airborne as quickly as possible to eliminate the drag caused by tall grass, soft sand, mud, and snow, and may or may not require climbing over an obstacle. The technique makes judicious use of ground effect and requires a feel for the WSC aircraft and fine control touch. These same techniques are also useful on a rough field where it is advisable to get the aircraft off the ground as soon as possible to avoid damaging the landing gear.

Soft surfaces or long, wet grass usually reduce the aircraft’s acceleration during the takeoff roll so much that adequate takeoff speed might not be attained if normal takeoff techniques were employed.

It should be emphasized that the WSC aircraft is different from most aircraft. The high wing creates a high center of gravity in which the front wheel can bog down in soft fields and flip the WSC aircraft forward. The propeller in the back pushing down on the front wheel also contributes to this unique situation. This is a limitation for WSC aircraft that should not be ignored. WSC aircraft that land in soft fields or sand may not be able to take off. There is a wide variation of manufacturer designs with the least preferable being a skinny, high pressure, highly loaded front tire. WSC aircraft with large wide tires that can be operated at low pressure are designed for operation in soft and rough fields. [Figures 7-11 through 7-13]

Figure 7-11. Soft field takeoff limitation for WSC aircraft: front wheel digs in and WSC aircraft rolls forward.

Figure 7-12. Example of a WSC aircraft designed with a wide low-pressure front wheel for soft field operation.

Figure 7-13. Grass fields are commonly used for WSC operations but require a longer time to accelerate to takeoff speed.

Correct takeoff procedure for soft fields and rough fields is quite different from that appropriate for short fields with firm, smooth surfaces. To minimize the hazards associated with takeoffs from soft or rough fields, support of the aircraft’s weight must be transferred as rapidly as possible from the wheels to the wings as the takeoff roll proceeds. Establishing and maintaining a relatively high angle of attack with a nose-high pitch attitude as early as possible achieves this.

Stopping on a soft surface, such as mud, snow or sand, might bog the aircraft down; therefore, it should be kept in continuous motion with sufficient power while lining up for the takeoff roll.

Takeoff Roll

As the aircraft is aligned with the takeoff path, takeoff power is applied smoothly and rapidly. As the aircraft accelerates, the control bar is moved full forward to the front tube to establish a positive angle of attack and to reduce the weight supported by the nosewheel because any lift on the wing takes load off of the landing gear.

When the aircraft is held at a nose-high attitude throughout the takeoff run and as speed increases and lift develops, the wings progressively relieve the wheels of more and more of the WSC’s weight, thereby minimizing the drag caused by surface irregularities or adhesion. If this attitude is accurately maintained, the aircraft virtually flies itself off the ground, becoming airborne at airspeed slower than a safe climb speed because of ground effect. [Figure 7-14]

Figure 7-14. Rough and soft field takeoff.

Lift-Off and Initial Climb

After becoming airborne, the nose should be lowered very gently with the wheels clear but just above the surface to allow the aircraft to utilize ground effect to accelerate to V_Y, or V_X if obstacles must be cleared. Extreme care must be exercised immediately after the aircraft becomes airborne and while it accelerates to avoid settling back onto the surface. An attempt to climb prematurely or too steeply may cause the aircraft to settle back to the surface as a result of losing the benefit of ground effect. An attempt to climb out of ground effect before sufficient climb airspeed is attained may result in aircraft incapacity to continue climbing as the ground effect area is traveled, even with full power for lower powered WSC aircraft. Therefore, it is essential that the aircraft remain in ground effect until at least V_X is reached. This requires a feel for the WSC aircraft and a very fine control touch in order to avoid overcontrolling the pitch control as required control pressures change with aircraft acceleration. Simply getting off the ground as quickly as possible and flying in ground effect is the goal.

In addition to normal takeoffs, additional common errors in the performance of soft/rough field takeoffs are:

Attempting a takeoff with a WSC that is not equipped with the proper tires.
Minimum air pressure not used in tires.
Insufficient control bar forward pressure during initial takeoff roll, resulting in inadequate angle of attack.
Poor directional control.
Climbing too steeply after lift-off.
Abrupt and/or excessive pitch control while attempting to level off and accelerate after lift-off.
Allowing the aircraft to “mush” or settle resulting in an inadvertent touchdown after lift-off.
Attempting to climb out of ground effect area before attaining sufficient climb speed.

Flight Literacy Recommends

Short Field Takeoff and Steepest Angle Climb in Weight-Shift-Control Aircraft

Filed Under: WSC Takeoff and Departure Climbs

Takeoffs and climbs from fields in which the takeoff area is short or the available takeoff area is restricted by obstructions require the pilot to operate the WSC aircraft at the limit of its takeoff performance capabilities. To depart from such an area safely, the pilot must exercise positive and precise control of attitude and airspeed so that takeoff and climb performance results in the shortest ground roll and the steepest angle of climb.

The achieved result should be consistent with the performance section of the AFM/POH. In all cases, the power setting, trim setting, airspeed, and procedures prescribed by the manufacturer should be followed.

In order to accomplish a short field takeoff and steepest angle climb safely, the pilot must have adequate knowledge in the use and effectiveness of the best angle-of-climb (V_X) speed and the best rate-of-climb (V_Y) speed for the specific make and model of WSC aircraft being flown.

The speed for V_X is that which results in the greatest gain in altitude for a given distance over the ground. V_X is usually less than V_Y but greater than minimum controlled airspeed. It should be noted that this maneuver is not performed in normal situations. Flying at V_X speed close to the ground in gusty winds can result in a stall with catastrophic consequences.

If clearing an obstacle is questionable, the WSC aircraft should be packed up and trailered away. If a pilot decides to perform a short field takeoff, then a number of factors can be optimized to contribute to a short field takeoff such as leaving your passenger and/or baggage in the area, waiting for favorable winds or lower density altitude, and picking the longest runway path with the shortest obstacle to clear.

However, if a short field takeoff is going to be performed and all possible factors have been optimized, the following procedure is provided. The procedure is similar to the normal takeoff but the following additional procedure is used for this maneuver.

Takeoff Roll

Taking off from a short field requires the takeoff to be started from the very beginning of the takeoff area. The WSC manufacturer’s recommended specific trim setting should be set before starting the takeoff roll. This permits the pilot to give full attention to the proper technique and the aircraft’s performance throughout the takeoff.

Some authorities prefer to hold the brakes until the maximum obtainable engine revolutions per minute (rpm) is achieved before allowing the WSC aircraft to begin its takeoff run. However, it has not been established that this procedure results in a shorter takeoff run in all WSC aircraft, many of which can not hold the brakes at full throttle. If the brakes are not held with the throttle advanced to full and then released, takeoff power should be applied immediately to full throttle as fast as possible without the engine bogging down to accelerate the aircraft as rapidly as possible. The WSC aircraft should be allowed to roll with the wing finding the trim position for minimum drag during acceleration to the lift-off speed.

Lift-Off and Climb Out

At V_X speed, the WSC aircraft should be smoothly and firmly rotated by applying control bar forward pressure to an attitude that results in the V_X airspeed. After becoming airborne, a wings-level climb should be maintained at V_X until obstacles have been cleared. Thereafter, the pitch attitude may be lowered slightly and the climb continued at V_Y speed until reaching a safe maneuvering altitude.

Remember that an attempt to rotate off the ground prematurely or to climb too steeply may cause the WSC aircraft to settle back to the runway or into the obstacles. Even if the aircraft remains airborne, the initial climb remains flat and climb performance/obstacle clearance ability is seriously degraded until V_X airspeed is achieved. [Figure 7-10]

In addition to normal takeoffs, common errors in the performance of short field takeoffs are:

Deciding to do a questionable short field takeoff when the WSC aircraft can be packed up and driven away.
Failure to adequately determine the best path with the longest run and shortest obstacle.
Failure to utilize all available runway/takeoff area.
Failure to wait for the best atmospheric conditions of density altitude and wind direction.
Failure to reduce all possible weight from the WSC aircraft.
Failure to have the WSC aircraft properly trimmed prior to takeoff.
Premature lift-off resulting in high drag.
Holding the WSC aircraft on the ground unnecessarily.
Inadequate rotation resulting in excessive speed after lift-off.
Inability to attain/maintain best VX airspeed.
Fixation on the airspeed indicator during initial climb.

Flight Literacy Recommends

Ground Effect on Takeoff in Weight-Shift-Control Aircraft

Filed Under: WSC Takeoff and Departure Climbs

Ground effect is a condition of improved performance encountered when the aircraft is operating very close to the ground. Ground effect can be detected and measured up to an altitude of about one wingspan above the surface. [Figure 7-9] However, ground effect is most significant when the WSC aircraft is maintaining a constant attitude at low airspeed and low altitude. Examples are during takeoff when the aircraft lifts off and accelerates to climb speed, and also during the landing flare before touchdown. When the wing is under the influence of ground effect, there is a reduction in upwash, downwash, and wingtip vortices.

Since the WSC wing is a high wing aircraft, the effects are not as pronounced as a low wing airplane, but during rotation, the reduction in induced drag is about 25 percent and decreases as the WSC aircraft climbs. At high speeds where parasite drag dominates, induced drag is a small part of the total drag. Consequently, the effects of ground effect are of greater concern during takeoff and landing.

On takeoff, the takeoff roll, lift-off, and the beginning of the initial climb are accomplished in the ground effect area. As the aircraft lifts off and climbs out of the ground effect area the following occurs.

The WSC aircraft requires an increase in angle of attack to maintain the same lift coefficient.
The WSC aircraft experiences an increase in induced drag and thrust required.

Due to the reduced drag in ground effect, the aircraft may seem capable of taking off below the recommended airspeed with less thrust. However, as the aircraft rises out of ground effect with an insufficient airspeed, initial climb performance may prove to be marginal due to increased drag. Under conditions of high density altitude, high temperature, and/or maximum gross weight, the aircraft may become airborne at an insufficient airspeed but unable to climb out of ground effect. Consequently, the aircraft may not be able to clear obstructions or may settle back on the runway. The point to remember is that additional power is required to compensate for increases in drag that occur as an aircraft leaves ground effect. But during an initial climb, the engine is already developing maximum power. The only alternative is to lower pitch attitude to gain additional airspeed, which results in inevitable altitude loss. Therefore, under marginal conditions, it is important that the aircraft take off at the recommended speed that provides adequate initial climb performance.

Ground effect is important to normal flight operations. If the runway is long enough, or if no obstacles exist, ground effect can be used to advantage by utilizing the reduced drag to improve initial acceleration. Additionally, the procedure for takeoff from unsatisfactory surfaces is to take as much weight on the wings as possible during the ground run, and to lift off with the aid of ground effect before true flying speed is attained. It is then necessary to reduce the angle of attack to attain normal airspeed before attempting to fly away from the ground effect area.

Flight Literacy Recommends

Crosswind Takeoff in Weight-Shift-Control Aircraft

Filed Under: WSC Takeoff and Departure Climbs

While it is usually preferable to take off directly into the wind whenever possible or practical, there are many instances when circumstances or judgment indicate otherwise. Therefore, the pilot must be familiar with the principles and techniques involved in crosswind takeoffs, as well as those for normal takeoffs.

The manufacturers maximum wind and crosswind component in the POH should not be exceeded. The following procedures are for operation within these limitations.

Takeoff Roll

The technique used during the initial takeoff roll in a crosswind is generally the same as used in a normal takeoff, except that the pilot must control the wing’s tendency to weathervane into the wind during the takeoff roll. Additionally, the pilot should keep the WSC aircraft on the ground and accelerate to a higher speed before rotation.

As the aircraft is taxied into takeoff position, it is essential that the windsock and other wind direction indicators be checked so that the presence of a crosswind may be recognized and anticipated. During taxi and takeoff, the windward side of the wing needs to be slightly lowered so as to not let the wind get under it and lift it off; but not too low or additional pilot effort is required and unnecessary stress is placed on the carriage.

The crosswind takeoff is performed similar to the normal takeoff except two different techniques are utilized. First, as the WSC aircraft accelerates and the pilot steers the carriage straight down the runway, the wing will want to weathervane into the wind. This creates stress on the wing attachment to the carriage, the carriage mast, and the keel of the carriage. Therefore, the pilot must hold the wing control bar straight to the carriage which requires significant force and muscle. Second, the pilot must accelerate to a higher speed before rotating to account for the crosswind component. This requires the nose to be held down to prevent the WSC from popping off the ground before the higher airspeed is obtained.

Since this technique requires the pilot to muscle the wing rather than using a light touch, it requires a mastery of the normal takeoff before crosswind takeoffs should be attempted. As the WSC aircraft accelerates down the runway, the forces of the wing try to weathervane it into the wind and the nose raises up to trim. The wing should be held straight with the nose down until rotation where the wing is held straight and the nose raised.

Rotation and Lift-Off

When a faster rotation speed than normal takeoff is achieved, a smooth but quicker push out to rotate is desired to get the front and rear wheels into the air quickly, avoiding any tendency to remain on the rear wheels. After lift-off, the WSC automatically rotates into the relative wind since momentum is straight down the runway and the characteristics of the wing point it directly into the relative wind. The WSC sets up the wind correction angle (or crab angle as it is also called) as it lifts off. [Figure 7-7]

Figure 7-7. Wing correction angle (or crab angle as is is commonly called).

Initial Climb

After lift-off, the WSC aircraft is pointed toward the wind and the ground track is headed straight down the runway centerline. Maintain this ground track aligned directly down the centerline of the runway “crabbing” into the wind. Crabbing is a term used to adjust flight controls into the crosswind to maintain a straight ground track while the WSC is pointed towards the wind, as seen in Figure 7-8. To maintain the ground track it is important to look straight down the runway centerline and steer to stay on that ground track even though the WSC is pointed towards the wind and not directly down the runway. Because the force of a crosswind may vary markedly within a few hundred feet of the ground, frequent checks of actual ground track should be made [Figure 7-7] or the WSC could drift to the side if the wind correction angle is not maintained. The remainder of the climb technique is the same used for normal takeoffs and climbs maintaining the proper ground track with the proper wing correction angle/crab angle. [Figure 7-8]

In addition to normal takeoffs, additional common errors in the performance of crosswind takeoffs are:

Letting the windward side of the wing get too high.
Allowing the wing to weathervane into the wind during the takeoff roll.
Not obtaining additional speed before rotation.
Too slow of a rotation during lift-off.
Inadequate drift correction after lift-off.

Flight Literacy Recommends

Normal Takeoff in Weight-Shift-Control Aircraft (Part Two) the Initial Climb

Filed Under: WSC Takeoff and Departure Climbs

Initial Climb

Upon lift-off, the WSC aircraft should be flying at the approximate pitch attitude that allows it to accelerate to at least the manufacturers takeoff safety speed. This is usually close to the best climb rate speed V_Y providing the greatest altitude gain in a period of time. Higher speeds should be used if the air is turbulent to assure the WSC does not stall from a strong wind gust. This speed should be maintained during the initial climb out in case of an engine failure. This is especially important with higher power engines and larger wings to avoid a high pitch attitude during this critical phase of the takeoff. With a lower pitch attitude and a faster speed, the WSC aircraft can recover easier from an engine failure on takeoff. This is discussed in greater detail in the emergency procedures chapter of this handbook. For example, from liftoff to 200 feet it is a good practice to keep a low pitch angle to anticipate an engine failure; above 200 feet, V_Y can be used as a climb speed. [Figures 7-4 and 7-5]

Figure 7-4. Initial takeoff grass strip with control bar pulled in slightly for a higher speed after liftoff in case of engine failure.

Figure 7-5. Best climb speed control bar position for this WSC is shown after initial climb where there is sufficient altitude for easy recovery in case of engine failure.

After liftoff and throughout the climb, the engine instruments should be checked for proper cooling and oil pressure (if so equipped) since this is the critical time when temperature rises and should stabilize within the manufacturer’s specifications.

The manufacturer’s recommended takeoff power should be maintained until reaching an altitude of at least 500 feet above the surrounding terrain or obstacles. The combination of V_Y and takeoff power assures the maximum altitude gained in the time during takeoff. This provides the pilot the greatest altitude from which the aircraft can be safely maneuvered in case of an engine failure or other emergency.

Since the power on the initial climb is fixed at the takeoff power setting, the airspeed must be controlled by making slight pitch adjustments using the control bar. However, the pilot should not fixate on the airspeed indicator when making these pitch changes, but continue to scan outside to adjust the attitude in relation to the horizon and the feel of the aircraft. The WSC aircraft can be flown by using bar position and the feel of the air to determine proper airspeed; it is not necessary to look at the airspeed indicator to determine exact airspeed. In accordance with the principles of flying a WSC aircraft, the pilot should first make the necessary pitch change with reference to the bar position, and then glance at the airspeed indicator as a check to see if the new speed is correct.

After the recommended climb airspeed has been established and a safe maneuvering altitude has been reached, the power should be adjusted to the recommended climb setting (if different) and the WSC aircraft trimmed (if so equipped) to relieve the control pressures. This makes it easier to hold a constant attitude and airspeed.

During initial climb, it is important that the takeoff path remain aligned with the runway to avoid drifting into obstructions or the path of another aircraft that may be taking off from a parallel runway. Proper scanning techniques are essential to a safe takeoff and climb, not only for maintaining attitude and direction, but also for collision avoidance in the airport area. [Figure 7-6]

Figure 7-6. Pilots view showing WSC centered in the middle of the runway during initial climb.

When the student pilot nears the solo stage of flight training, it should be explained that the aircraft’s takeoff performance is much different when the instructor is out of the aircraft. Due to decreased load, the WSC aircraft becomes airborne sooner and climbs more rapidly. The pitch attitude that the student has learned to associate with initial climb differs significantly due to decreased weight. This can be a dramatic effect since a 250 pound instructor could reduce the total weight of the WSC aircraft by 30 percent. This gives the student the sensation of lying on his or her back during initial takeoff and the reaction is to let off the throttle with serious consequences if the student is using the foot throttle. It must be emphasized by the instructor that the student will seem to be rotated and going straight up, but not to let up on the throttle. The reaction of the student is to pull in the control bar to lower the high pitch attitude. This is where the cruise throttle should be used to eliminate this common problem. The increase in performance is significant when the student first solos in the same aircraft, which must be explained and understood. If the situation is unexpected, it may result in increased tension that may remain throughout the flight. Frequently, the existence of this tension and the uncertainty that develops due to the perception of an “abnormal” takeoff results in poor performance on the subsequent landing.

Common errors in the performance of normal takeoffs and departure climbs are:

Failure to adequately clear the area prior to taxiing into position on the active runway. • Abrupt use of the throttle.
Letting off the foot throttle after takeoff.
Failure to check engine instruments for signs of malfunction after liftoff and climb.
Failure to anticipate the aircraft’s left turning tendency on initial acceleration and takeoff.
Overcorrecting for left turning tendency.
Overcorrecting for roll.
Relying solely on the airspeed indicator rather than developing a feel for indications of speed and controllability during acceleration and lift-off.
Failure to attain proper lift-off attitude.
Overcontrol of pitch during initial lift-off to climbout.
Failure to attain/maintain best rate of climb airspeed (V_Y).
Failure to employ the principles of attitude flying during climb-out, resulting in “chasing” the airspeed indicator.

Flight Literacy Recommends

Normal Takeoff in Weight-Shift-Control Aircraft (Part One)

Filed Under: WSC Takeoff and Departure Climbs

Prior to Takeoff

Before taxiing onto the runway or takeoff area, the pilot should ensure that the engine is operating properly and that all controls, including trim (if equipped), are set in accordance with the before takeoff checklist. In addition, the pilot must make certain that the approach and takeoff paths are clear of other aircraft. At uncontrolled airports, pilots should announce their intentions on the common traffic advisory frequency (CTAF) assigned to that airport. When operating from an airport with an operating control tower, pilots must contact the tower operator and receive a takeoff clearance before taxiing onto the active runway.

It is not recommended to take off immediately behind another aircraft, particularly large, heavily loaded transport airplanes because of the wake turbulence that is generated. Even smaller aircraft can generate vortices that can cause the WSC aircraft to lose control during takeoff. Always wait for aircraft vortices to clear before taking off.

While taxiing onto the runway, the pilot can select ground reference points that are aligned with the runway direction as aids to maintaining directional control during the takeoff. These may be runway centerline markings, runway lighting, distant trees, towers, buildings, or mountain peaks.

Normal Takeoff

A normal takeoff is one in which the aircraft is headed into the wind, or the wind is very light. Also, the takeoff surface is firm and of sufficient length to permit the aircraft to gradually accelerate to normal lift-off and climb-out speed, and there are no obstructions along the takeoff path.

There are two reasons for making a takeoff as nearly into the wind as possible. First, the aircraft’s speed while on the ground is much lower than if the takeoff were made downwind, thus reducing wear and stress on the landing gear. Second, a shorter ground roll and, therefore, much less runway length is required to develop the minimum lift necessary for takeoff and climb. Since the aircraft depends on airspeed in order to fly, a headwind provides some of that airspeed, even with the aircraft motionless, from the wind flowing over the wings.

Takeoff Roll

After taxiing onto the runway, the WSC aircraft should be carefully aligned with the intended takeoff direction and the nosewheel positioned straight down the runway on the centerline. After releasing the brakes, the throttle should be advanced smoothly and continuously to takeoff power. [Figure 7-2] This can be done with the foot or the hand cruise throttle.

Figure 7-2. Lined up in the middle of the runway and ready to apply full power for takeoff.

The advantage of using the foot throttle is that the takeoff can be aborted quickly if required. The disadvantage is that the foot can slip off or be knocked off during the critical takeoff phase of flight. The advantage of using the hand cruise throttle during takeoff is having a solid and set throttle that the pilot does not have to worry about holding during the takeoff phase of flight. Students have been known to release the foot throttle on takeoff, resulting in catastrophic consequences during the lift-off and initial climb phases of flight. Students may be encouraged to use the hand throttle by the instructor or the instructor must be able to immediately apply the hand or secondary foot throttle if a student lets up on the throttle during this critical takeoff and climb phase.

An abrupt application of power may cause the aircraft to yaw sharply to the left (or right depending on the propeller rotation) because of the torque effects of the engine and propeller. This is most apparent in high horsepower engines. As the aircraft starts to roll forward, the pilot should ensure that both feet are on the front steering fork and not applying the brake.

As speed is gained, the control bar fore and aft pitch tends to assume a neutral trim position. The wing should be maintained level side to side with the control bar. At the same time, directional control should be maintained with smooth, prompt, positive nosewheel steering throughout the takeoff roll. The effects of engine torque at the initial speeds tend to pull the nose to the left (or right depending on the propeller rotation). The pilot must steer the WSC aircraft straight down the middle of the runway with the feet. The positioning of the wing has no effect of steering on the ground. The common saying among WSC pilots is “you steer with your feet, you fly with your hands.”

While the speed of the takeoff roll increases, increasingly more pressure is felt on the control bar to the ground roll trim position. Letting the wing pitch pressures determine the fore and aft control bar position provides the least drag for the WSC aircraft to accelerate. The pilot maintains directional control down the center of the runway with the foot steering, keeps the wings level side to side, and allows the wing to determine the pitch angle during the acceleration.

Lift-Off

Since a good takeoff depends on the proper takeoff attitude, it is important to know how this attitude appears and how it is attained. The ideal takeoff attitude requires only minimum pitch adjustments shortly after the airplane lifts off to attain the speed for the best rate of climb (V_Y). [Figure 7-3] The pitch attitude necessary for the aircraft to accelerate to V_Y speed should be demonstrated by the instructor and memorized by the student. Initially, the student pilot may have a tendency to hold excessive control bar forward/nose up pressure just after lift-off, resulting in an abrupt pitch-up. The flight instructor should be prepared for this. For a normal takeoff, the WSC aircraft should lift off the ground gradually and smoothly.

Figure 7-3. Initial roll and takeoff attitude.

Each type of WSC aircraft has a best pitch attitude for normal lift-off; however, varying conditions may make a difference in the required takeoff technique. A rough field, a smooth field, a hard surface runway, or a short or soft, muddy field, calls for a slightly different technique as does smooth air in contrast to a strong, gusty wind. The different techniques for those other-than-normal conditions are discussed later in this chapter.

As the WSC aircraft accelerates and obtains the speed it needs to lift off, a slight push forward on the control bar provides the initial attitude to lift-off. This is often referred to as “rotating.” At this point, the climb speed should be immediately established for the particular condition. For calm winds, this would be the trim position or the manufacturer recommended takeoff safety airspeed. The wings must be kept level by applying side to side pressure as necessary.

Since some forward pressure was required to rotate, this pressure must be relaxed smoothly so that takeoff attitude is not too high. This requires the control bar being brought back to trim and applying some nose down pressure to avoid popping off as the WSC aircraft leaves the ground. Each make and model is different and the high power WSC aircraft must provide more nose down pressure after rotation to keep the attitude low. A good takeoff is a smooth and gradual liftoff. It is important to hold the correct attitude constant after rotation and liftoff.

As the aircraft leaves the ground, the pilot must continue to be concerned with maintaining the wings in a level attitude, as well as holding the proper pitch attitude. An outside visual scan to attain/maintain proper pitch and bank attitude must be intensified at this critical point.

During takeoffs in a strong, gusty wind, it is advisable that an extra margin of speed be obtained before the WSC aircraft is allowed to leave the ground. A takeoff at the normal takeoff speed may result in a lack of positive control, or a stall, when the WSC aircraft encounters a sudden lull in strong, gusty wind, or other turbulent air currents. In this case, the pilot should allow the aircraft to stay on the ground longer by pulling the control bar towards the chest keeping the nose down to attain more speed; then make a smooth, positive rotation to leave the ground.

Flight Literacy Recommends

Whip Stall and Tumble Awareness

Filed Under: WSC Flight Maneuvers

As discussed in chapter 2, the WSC aircraft does not have a tail with a vertical stabilizer similar to an airplane, and there is the possibility of the wing tucking and tumbling. If a WSC tumbles, this will most likely result in a structural failure of the WSC and serious injury or death to the pilot and/or passenger. It is most important for the pilot to understand tumble awareness and use all means to avoid such an occurrence. The pilot can avoid a tuck and tumble by:

Flying within the manufacturer’s limitations.
Flying in conditions that are not conducive to tucks and tumbles.
Obtaining the proper training in pitch stability for the WSC.

Flying within the manufacturer’s pitch and airspeed limitations is simply adhering to the POH/AFM limitations. Depending on the manufacturer, this could mean no full power stalls, not exceeding pitch limits of ± 40 pitch angle, not flying below the safe flying speed in turbulence, etc. Manufacturer’s limitations are provided for the specific aircraft to avoid tucks and tumbles.

Preflight preparation is the first step to avoid the possibility of a tuck/tumble to avoid flying in strong weather conditions. This could be strong winds that create wind shear or strong convective thermals that create updrafts and downdrafts. This weather analysis is part of the preflight preparation weather analysis. The second pilot decision regarding appropriate weather while flying is to look at the environment during flight to understand and evaluate the situation. Weather conditions should always be evaluated as the flight progresses with ADM used to determine the best outcome for the situation. This could be turning back or landing depending on the situation.

As a student or pilot progresses, turbulence will be encountered. Use the procedures for flying straight and level as shown in Figure 6-8. Use this exercise as a foundation for developing pitch control awareness to keep the wing managed with proper control bar pitch and throttle control.

Figure 6-8. Thermal updraft and downdraft sequence.

For high pitch angles, the POH may have specific procedures that should be followed for the particular WSC aircraft, but the following general guidelines are provided. After reviewing the aerodynamic aspects of the tuck/tumble in chapter 2, refer to the following tuck/tumble awareness and avoidance procedures.

As defined in the aerodynamics section, a whip stall is a high pitch angle when the tips stall because they exceed the critical angle of attack. This can be the result of strong turbulence or power-on stall, pilot induced, or any combination of these factors. A pilot must avoid all of these factors to avoid the possibility of a whip stall resulting in a tumble, but the following procedures are provided for tumble avoidance in case a whip stall or a nose rotating down below the manufacturer’s limitations is encountered.

The aircraft rotates nose down. [Figure 6-23, Whip Stall to Phase 1] Push the control bar out to the front tube and level wings while increasing to full power and keeping control bar full out to reduce overpitching. [Figure 6-23, Phase 1 to Phase 2] If rotation is so severe that it progresses to phase 4 and the WSC aircraft is tumbling, the ballistic parachute (if so equipped) should be deployed.

Figure 6-23. Whip stall/tuck/tumble sequence.

There are other weather situations in which the nose is not at a high pitch attitude, where the back of the wing can get pushed up and enter phase 1 without an unusually high pitch attitude or whip stall. If pitched nose low, increase to full power while pushing the control bar full out to reduce nosedown pitching rotation. Generally, the control bar full out and full-throttle create a nose-up moment.

It takes extremely strong weather conditions and/or pilot error to tuck/tumble a WSC aircraft. Experienced pilots fly all day in moderate turbulence, but building experience flying in turbulence should be approached slowly and cautiously to determine the pilot and aircraft capabilities and limitations.

A Scenario

The following is one example of a scenario that could lead to a tuck/tumble. It is based on a viable training program in one location but lack of experience in another location.

A student obtains his or her pilot’s license with the minimum number of hours for the pilot certificate. The new pilot trained, soloed, and obtained his or her license only in conditions near the ocean where there was typically an inverted midday sea breeze with little to no convective turbulence (thermals). This developed confidence for flying in winds up to 15 knots but no experience was gained in thermals. In fact, the pilot was not aware that strong thermals could be hazardous.

Now, with a new license, the pilot visits his parents in the middle of the high desert of Colorado. Unfamiliar with the local conditions, the new pilot gets a weather report of winds to 15 knots, something the pilot has experienced before. By the time the pilot arrives at the airport, discusses the situation with the airport officials, and sets up the WSC aircraft, it is 2:00 in the afternoon. The wind is generally calm but increasing to 15 knots occasionally. There are towering cumulus clouds in the sky surrounding the current airport similar to clouds that the pilot had seen far inland from where he or she took instruction and soloed.

The pilot takes off in relatively calm winds, but it is unusually bumpy air. Without any experience in the high desert or with thermal conditions, the pilot has misjudged the conditions and is flying in strong thermal convection. The new pilot climbs out trying to get above the turbulence, which usually works near the beach because of the mechanical turbulence near the ground. However, the turbulence increases.

As the pilot is climbing to a pattern altitude of 1,000 feet AGL at full throttle, the aircraft is pitched nose up while the pilot lets the force of the updraft raise the nose. Never has the pilot felt the nose rise with this type of force before. The pilot is shocked and disoriented at this high pitch attitude, but eventually lets up on the throttle. But now at an unusually high pitch angle, the WSC nose flies into the downdraft of the thermal. At the same time, the updraft is still pushing up on the tips of the wing while the downdraft is pushing down on the nose creating a forward rotation with a weightless sensation. Before the pilot knows it, the wing is rotating pitch down for a vertical dive. [Phase 1 in Figure 6-23] The student remembers from training that “in a nose down rotation into a steep dive the control bar is pushed full forward and full throttle applied” and initiates this corrective action. The pilot reaches the vertical dive, but because of the corrective action the WSC aircraft recovers from the dive and proceeds back to land safely.

What went wrong? What were the errors? How could this near catastrophe have been avoided?

In a new area and unfamiliar with the conditions, the new pilot should have asked the local instructor or other pilots about the conditions for the day. Local WSC pilots are a great resource for flying the local conditions, but pilots of any category aircraft are knowledgeable of the conditions and could have provided advice for the new pilot. This might have prevented the new pilot from attempting this flight.
Flying in a new environment and not understanding the power of midday thermals in the high desert should have forced the new pilot to scrap this midday flight. The pilot should have started flying in the morning when there is little thermal convection and gained experience and understanding about the weather in this new area.
Better preflight planning should have been accomplished, especially in a new location. The pilot should have known to obtain convective information and realize it was going to be too bumpy for his or her limited experience. The pilot was accustomed to seeing towering cumulus clouds where he or she trained, but they were way inland and not in the normal flying area. Here clouds were observed all around.
Site observations indicated strong thermal activity. Observation of winds picking up to 15 knots and then becoming calm normally indicates thermal activity. The pilot was familiar with steady 15 knot winds, but did not understand that calm wind increasing cyclically to 15 knots indicates thermal activity.
The pilot did not initially react to the updraft and resultant high pitch angle properly because pitch management habits had not been developed. The pilot hit the updraft and allowed the force of the updraft to move the control bar forward, increasing the pitch angle while not letting up on the throttle immediately. Both the control bar forward and full throttle forced the nose too high, creating the high pitch angle and whip stall condition. At the same time, the WSC aircraft flew into the downdraft, starting the nosedown rotation.
If the pilot had reacted quickly, pulled in the bar while letting up on the throttle and immediately going into the strong thermal, the high pitch angle would not have been achieved and the strong forward rotation would not have happened so abruptly.

After the series of errors occurred, the pilot finally performed the preventive action to avoid a tumble—from the basic training of “If the WSC is at a high pitch angle and the nose starts to rotate down to a low pitch angle, increase to full power while pushing the control bar full out to avoid a tumble.”

Flight Literacy Recommends

Stalls in Weight-Shift-Control Aircraft

Filed Under: WSC Flight Maneuvers

A stall occurs when the smooth airflow over the aircraft’s wing root is disrupted and the lift degenerates rapidly. This is caused when the wing root exceeds its critical angle of attack. This can occur at any airspeed in any attitude with any power setting.

The practice of stall recovery and the development of awareness of stalls are of primary importance in pilot training. The objectives in performing intentional stalls are to familiarize the pilot with the conditions that produce stalls, to assist in recognizing an approaching stall, and to develop the habit of taking prompt preventive or corrective action.

Pilots must recognize the flight conditions that are conducive to stalls and know how to apply the necessary corrective action. They should learn to recognize an approaching stall by sight, sound, and feel. The following cues may be useful in recognizing the approaching stall:

Positioning the control bar toward the front tube
Detecting a stall condition by visually noting the attitude of the aircraft for the power setting
Hearing the wind decrease on the structure and pilot
Feeling the wind decrease against the pilot
Sensing changes in direction or speed of motion, or kinesthesia—probably the most important and best indicator to the trained and experienced pilot. If this sensitivity is properly developed, it warns of a decrease in speed or the beginning of a settling or mushing of the aircraft.

During the practice of intentional stalls, the real objective is not to learn how to stall an aircraft, but to learn how to recognize an approaching stall and take prompt corrective action. Though the recovery actions must be taken in a coordinated manner, they are broken down into the following three actions for explanation purposes.

First, at the indication of a stall, the pitch attitude and angle of attack must be decreased positively and immediately. Since the basic cause of a stall is always an excessive angle of attack, the cause must first be eliminated by releasing the control bar forward pressure that was necessary to attain that angle of attack or by moving the control bar backwards. This lowers the nose and returns the wing to an effective angle of attack.

The amount of movement used depends on the design of the wing, the severity of the stall, and the proximity of the ground. In some WSC aircraft, the bar can be left out and as the nose stalls, the wing lowers to an angle of attack and keeps flying since the tips do not stall. However, even though WSC aircraft generally have gentle stall characteristics, higher performance wings may not be as forgiving. Therefore during a stall, the control bar should be moved back to reduce the angle of attack and properly recover from the stall. The object for all WSC aircraft is to reduce the angle of attack but only enough to allow the wing to regain lift as quickly as possible and obtain the appropriate airspeed for the situation with the minimum loss in altitude.

Power application in a stall is different than an airplane. Since power application in a WSC aircraft produces a nose-up moment after a stall has occurred and the pitch has decreased from the control bar movement, power should be applied. The flight instructor should emphasize, however, that power is not essential for a safe stall recovery if sufficient altitude is available. Reducing the angle of attack is the only way of recovering from a stall regardless of the amount of power used. Stall recoveries should be practiced with and without the use of power. Usually, the greater the power applied during the stall recovery, the less the loss of altitude.

Third, straight-and-level flight should be regained with coordinated use of all controls. Practice of power-on stalls should be avoided due to potential danger of whipstalls, tucks, and tumbles, as detailed later in this chapter.

Power-off (at idle) turning stalls are practiced to show what could happen if the controls are improperly used during a turn from the base leg to the final approach. The power-off straight-ahead stall simulates the attitude and flight characteristics of a particular aircraft during the final approach and landing.

Usually, the first few practices should include only approaches to stalls with recovery initiated as soon as the first buffeting or partial loss of control is noted. Once the pilot becomes comfortable with this power-off procedure, the aircraft should use some power and be slowed in such a manner that it stalls in as near a level pitch attitude as is possible. The student pilot must not be allowed to form the impression that in all circumstances a high pitch attitude is necessary to exceed the critical angle of attack, or that in all circumstances a level or near level pitch attitude is indicative of a low angle of attack. Recovery should be practiced first without the addition of power by merely relieving enough control bar forward pressure that the stall is broken and the aircraft assumes a normal glide attitude. Stall recoveries should then be practiced with the addition of power during the recovery to determine how effective power is in executing a safe recovery and minimizing altitude loss.

Stall accidents usually result from an inadvertent stall at a low altitude in which a recovery was not accomplished prior to contact with the surface. As a preventive measure, stalls should be practiced at a minimum altitude of 1,500 feet AGL or that which allows recovery no lower than 1,000 feet AGL. Recovery with a minimum loss of altitude requires a reduction in the angle of attack (lowering the aircraft’s pitch attitude), application of power, and termination of the descent without accelerating to a high airspeed and unnecessary altitude loss.

The factors that affect the stalling characteristics of the aircraft are wing design, trim, bank, pitch attitude, coordination, drag, and power. The pilot should learn the effect of the stall characteristics of the aircraft being flown. It should be reemphasized that a stall can occur at any airspeed, in any attitude, or at any power setting, depending on the total number of factors affecting the particular aircraft.

Whenever practicing turning stalls, a constant pitch and bank attitude should be maintained until the stall occurs. In a banked stall or if the wing rolls as it stalls, side to side control bar movement is required to level the wings as well as pull the bar back to reduce the angle of attack.

Power-Off Stall Manuever

The practice of power-off stalls is usually performed with normal landing approach conditions in simulation of an accidental stall occurring during landing approaches. Aircraft equipped with trim should be trimmed to the approach configuration. Initially, airspeed in excess of the normal approach speed should not be carried into a stall entry since it could result in an abnormally nose-high attitude. Before executing these practice stalls, the pilot must be sure the area is clear of other air traffic.

To start the power-off stall maneuver, reduce the throttle to idle (or normal approach power). Increase airspeed to the normal approach speed and maintain that airspeed. When the approach attitude and airspeed have stabilized, the aircraft’s nose should be smoothly raised to an attitude that induces a stall. If the aircraft’s attitude is raised too slowly, the WSC aircraft may slow only to minimum controlled airspeed and not be able to reach an angle of attack that is high enough to stall. The position of the control bar at which the WSC stalls can vary greatly for different manufacturers and makes/ models. Some can stall abruptly when the control bar is inches from the front tube.

If the aircraft’s attitude is raised too quickly, the pitch attitude could rise above the manufacturer’s limitation. A good rule of thumb is 3 to 4 seconds from stabilized approach speed to pull the control bar full forward. The wings should be kept level and a constant pitch attitude maintained until the stall occurs. The stall is recognized by clues, such as buffeting, increasing descent rate, and nose down pitching.

Recovering from the stall should be accomplished by reducing the angle of attack by pulling the bar back and accelerating only to the trim speed while simultaneously increasing the throttle to minimize altitude loss if needed. Once the WSC accelerated to trim speed, the control bar can be pushed out to return back to normal trim attitude and speed. If there is any rolling during the stall or the stall recovery the control bar should be moved side to side to maintain a straight heading.

It is not necessary to go into a steep dive in a WSC aircraft to recover from a stall. This only loses more altitude than required and should be discouraged. The nose should be lowered as necessary to regain flying speed and returned to a normal flight attitude as soon as possible. [Figure 6-22]

Figure 6-22. Power-off stall and recovery.

Recovery from power-off stalls should also be practiced from shallow banked turns to simulate an inadvertent stall during a turn from base leg to final approach. During the practice of these stalls, care should be taken that the turn continues at a uniform rate until the complete stall occurs. When stalling in a turn, it does not affect the recovery procedure. The angle of attack is reduced and the wings leveled simultaneously with power applied if needed for altitude control. In the practice of turning stalls, no attempt should be made to stall the aircraft on a predetermined heading. However, to simulate a turn from base to final approach, the stall normally should be made to occur within a heading change of approximately 90°. After the stall occurs, the recovery should be made straight ahead with minimum loss of altitude, and accomplished in accordance with the recovery procedure discussed earlier.

Flight Literacy Recommends

Slow Flight in Weight-Shift-Control Aircraft

Filed Under: WSC Flight Maneuvers

As discussed in chapter 2, the maintenance of lift and control of an aircraft in slow flight requires a certain minimum airspeed and angle of attack. This critical airspeed depends on certain factors, such as gross weight, load factors, and density altitude. The minimum speed below which further controlled flight is impossible is called the stalling speed. An important feature of pilot training is the development of the ability to estimate and “feel” the margin of speed above the stalling speed. Also, the ability to determine the characteristic responses of the aircraft at different airspeeds is of great importance to the pilot. The student pilot, therefore, must develop this awareness in order to safely avoid stalls and to operate an aircraft correctly and safely at slow airspeeds.

As discussed in chapter 2, the nose stalls while the tips keep flying. Therefore, the definition of stall speed of the WSC aircraft is the speed at which the nose starts stalling. The control bar is pushed forward and buffeting is felt on the control bar as the root reaches the critical angle of attack. Separation of the laminar airflow occurs, creating turbulence that can be felt in the control bar. There is a loss of positive roll control as the nose buffets and lowers as it loses lift.

Slow Flight

The objective of maneuvering during slow flight is to develop the pilot’s sense of feel and ability to use the controls correctly and to improve proficiency in performing maneuvers that require slow airspeeds.

Slow flight is broken down into two distinct speeds:

V_X and the short field descent speed that was discussed earlier, and,
Minimum controlled airspeed, the slowest airspeed at which the aircraft is capable of maintaining controlled flight without indications of a stall—usually 2 to 3 knots above stalling speed as discussed below.

The minimum controlled airspeed maneuver demonstrates the flight characteristics and degree of controllability of the aircraft at its minimum flying speed. By definition, the term “flight at minimum controllable airspeed” means a speed at which any further increase in angle of attack or load factor causes an immediate stall. Instruction in flight at minimum controllable airspeed should be introduced at reduced power settings with the airspeed sufficiently above the stall to permit maneuvering, but close enough to the stall to sense the characteristics of flight at very low airspeed—sloppy control, ragged response to control inputs, difficulty maintaining altitude, etc. Maneuvering at minimum controllable airspeed should be performed using both instrument indications and outside visual reference. It is important that pilots form the habit of frequent reference to the flight instruments, especially the airspeed indicator, while flying at very low airspeeds. However, the goal is to develop a “feel” for the aircraft at very low airspeeds to avoid inadvertent stalls and to operate the aircraft with precision.

The objective of performing the minimum controlled airspeed is to fly straight and level and make shallow level turns at minimum controlled airspeed. To begin a minimum controlled airspeed maneuver, the WSC is flown at trim speed straight and level to maintain a constant altitude. The nose is then raised as the throttle is reduced to maintain a constant altitude.

As the speed decreases further, the pilot should note the feel of the flight controls, pitch pressure, and difficulty of maintaining a straight heading with the increased side-to-side pilot input forces required to keep the wings level. At some point the throttle must be increased to remain level after the WSC has slowed below it’s maximum L_D speed. The pilot should also note the sound of the airflow as it falls off in tone. There is a large difference by manufacturer and model, but the bar generally should not be touching the forward tube at minimum controlled airspeed. For example, the control bar would be 1 to 3 inches from the front tube at minimum controlled airspeed. [Figure 6-21]

Figure 6-21. Minimum controlled airspeed maneuver.

The pilot should understand that when flying below the minimum drag speed (L/D_MAX), the aircraft exhibits a characteristic known as “speed instability.” If the aircraft is disturbed by even the slightest turbulence, the airspeed decreases. As airspeed decreases, the total drag increases resulting in a further loss in airspeed. Unless more power is applied and/or the nose is lowered, the speed continues to decay to a stall. This is an extremely important factor in the performance of slow flight. The pilot must understand that, at speeds less than minimum drag speed, the airspeed is unstable and will continue to decay if allowed to do so.

It should also be noted that the amount of power to remain level at minimum controlled airspeed is greater than that required at the minimum drag speed which is also the best glide ratio speed and the best rate of climb speed.

When the attitude, airspeed, and power have been stabilized in straight-and-level flight, turns should be practiced to determine the aircraft’s controllability characteristics at this minimum speed. During the turns, power and pitch attitude may need to be increased to maintain the airspeed and altitude. The objective is to acquaint the pilot with the lack of maneuverability at minimum controlled airspeed, the danger of incipient stalls, and the tendency of the aircraft to stall as the bank is increased. A stall may also occur as a result of turbulence, or abrupt or rough control movements when flying at this critical airspeed.

Once flight at minimum controllable airspeed is set up properly for level flight, a descent or climb at minimum controllable airspeed can be established by adjusting the power as necessary to establish the desired rate of descent or climb.

Common errors in the performance of slow flight are:

Failure to adequately clear the area.
Inadequate forward pressure as power is reduced, resulting in altitude loss.
Excessive forward pressure as power is reduced, resulting in a climb, followed by a rapid reduction in airspeed and “mushing.”
Inadequate compensation for unanticipated roll during turns.
Fixation on the airspeed indicator.
Inadequate power management.
Inability to adequately divide attention between aircraft control and orientation.